JFS Vol 77 Is 01 JAN 2012 pp R025-R041 PRODUCTION TECHNOLOGIES FOR REDUCED ALCOHOLIC WINES.pdf

R:Co

ncise

Revie

wsin

Food

Scien

ce

Production Technologies for ReducedAlcoholic WinesLeigh M. Schmidtke, John W. Blackman, and Samson O. Agboola

Abstract: The production and sale of alcohol-reduced wines, and the lowering of ethanol concentration in wines withalcohol levels greater than acceptable for a specific wine style, poses a number of technical and marketing challenges.Several engineering solutions and wine production strategies that focus upon pre- or postfermentation technologieshave been described and patented for production of wines with lower ethanol concentrations than would naturally arisethrough normal fermentation and wine production techniques. However, consumer perception and acceptance of thesensory quality of wines manufactured by techniques that utilize thermal distillation for alcohol removal is generallyunfavorable. This negative perception from consumers has focused attention on nonthermal production processes and thedevelopment or selection of specific yeast strains with downregulated or modified gene expression for alcohol production.The information presented in this review will allow winemakers to assess the relative technical merits of each of thetechnologies described and make decisions regarding implementation of novel winemaking techniques for reducingethanol concentration in wine.

Keywords: alcohol reduction, genetic engineering, glucose oxidase, osmotic distillation, reverse osmosis, Saccharomycescerevisiae, spinning cone, winemaking

IntroductionThe manufacture and sale of reduced alcoholic strength bever-

ages is fraught with legal complexities. Definitions of wine andwine products specify minimum ethanol concentrations of vary-ing quantity applicable for different countries. For example, inAustralia, products labeled as wine must contain greater than8% v/v ethanol (alcohol) (ANZFA 2002b). Fermented grapeproducts with an alcohol concentration less than this amount maynot fit this definition. Thus, the use of the term “Reduced AlcoholWine” to describe a product destined for the Australian marketmay not be permitted; however, the product could be branded asa “Reduced Alcohol Wine Product.” The term “Low Alcohol”may be applied to beverages derived from fermented grape juicethat contains less than 1.15% v/v ethanol and “Non-intoxicating”implies the beverage contains less than 0.5% v/v ethanol (ANZFA2002a). Further confusion arises from wine production techniquesusing early harvested grapes with naturally occurring low levels offermentable sugars, and consequently, naturally low alcohol con-centrations. These products may not have undergone any postfer-mentation process to modify alcohol levels but may still containless than the minimum specified ethanol concentration to be con-sidered a wine. Some countries have legislative complexity arisingfrom different government authorities regulating wine and re-duced alcohol wine. In the United States, wine as defined withinthe Federal Alcohol Administration Act, must contain between 7%and 24% v/v alcohol, while the Bureau of Alcohol, Tobacco andFirearms regulates labeling requirements. As dealcoholized wine

MS 20110811 Submitted 5/7/2011, Accepted 12/9/2011. Authors Schmidtke andBlackman are with Natl. Wine and Grape Industry Centre, and authors Schmidtke,Blackman, and Agboola are with School of Agricultural and Wine Sciences, CharlesSturt Univ., Wagga Wagga, NSW 2678, Australia. Direct inquiries to authorSchmidtke (E-mail: [email protected]).

products usually contain less than 7% v/v ethanol, labeling pro-visions are covered by a separate federal act administered by theFood and Drug Administration (Anon 2005). The use of the term“Partially Fermented Wine Product” may be suitable for somestock keeping units; however, the use of thermal distillation ormembrane processes for reduction of alcohol from wines preparedfrom grape juice that has been fermented to dryness (<2.0 g/Lsugar) could render this term unsuitable. Further confusion mayalso arise according to the technique of reducing the alcohol con-centration. The use of glucose oxidase (GOX) enzymes for thereduction of fermentable sugars may not be permitted as pro-cessing aids for wines in some countries or regions (van Oortand Canal-Llauberes 2002), but their use in the manufacture ofwine products or food products may be permissible. Such defi-nitions vary according to the specific labeling laws for individualcountries or economic trading zones, and exceptions based uponhistorical production of specific wine styles are notable. Through-out this review, the terms alcohol reduced, dealcoholized, and lowalcohol are used interchangeably in the context of wine produc-tion, although it is acknowledged that specific legal definitions ofthese terms may exist. This article is not intended to be a guideto the legalities or otherwise of the various production techniquesthat can be employed for reducing ethanol concentrations in fer-mented beverages, or a discussion of labeling or wine productionlaws associated with specific countries or economic trading zonesin which goods with reduced alcohol are manufactured and ex-ported. Producers who wish to develop a range of wines withlower than normal ethanol concentrations are strongly advised toseek expert opinion from the regulatory bodies and governmentorganizations appropriate for that manufacturer.

Production techniques for manufacturing low or reduced al-coholic strength beverages have been developed over the last 15to 20 y in order to satisfy a consumer demand for healthier al-coholic products. Decreasing alcohol consumption is a world-wide trend and lower alcohol consumption rates are associated

C© 2011 Institute of Food Technologists R©doi: 10.1111/j.1750-3841.2011.02448.x Vol. 71, Nr. 1, 2012 � Journal of Food Science R25Further reproduction without permission is prohibited

R:ConciseReviewsinFoodScience

Technologies for reduced alcoholic wines . . .

with certain positive health benefits (National Health and MedicalResearch Council [Australia] 2009). Beverages with reducedethanol concentrations are also more favorably excised in mostcountries thereby producing some competitive advantages forwine sales compared to full alcoholic strength wines. Produc-ers may also wish to marginally reduce alcohol concentrations infull-strength wines to correct balance and maintain consistency ofstyle between vintages or blends. It has also been reported thatalcohol reduction can lead to an alcohol “sweet spot” (Wollan2006). These sweet spots have been described when the alcohollevel in a given wine is varied by as little as ±0.1%. Signifi-cant differences in flavor intensities and balances are purportedlypresent in the favored sweet spot alcohol levels (Wollan 2006).This anecdotal evidence should be considered in light of recentinvestigations that demonstrate ethanol difference thresholds areapproximately 1.0% v/v (Yu and Pickering 2008). The produc-tion methods that are of most relevance to the wine industry,while not exhaustive, are summarized in Table 1 and generallyform the basis of discussion in this article. Technologies have beenclassified according to the stage of wine production they are typi-cally used; that is, pre, concurrent, or postalcoholic fermentation.However, some well-established “post fermentation” techniques,such as low-temperature distillation, have been applied during al-coholic fermentation for the removal of approximately 2% v/v ofethanol without significantly changing the concentration of otherwine constituents (Aguera and others 2010). This information willallow winemakers to assess the relative technical merits of each ofthe technologies described and make decisions regarding imple-mentation of novel winemaking techniques for reducing ethanolconcentration in wine.

Prefermentation Technologies for Limiting AlcoholProduction

Limiting alcohol production during fermentation by loweringthe concentration of fermentable sugars in juice through earlygrape harvest, juice dilution, or arresting fermentation, while sig-nificant levels of unfermented sugars remain in the wine are someof the options that enable wines with reduced alcohol levels tobe produced. Early grape harvest may result in wines that areorganoleptically undeveloped due to reduced flavor precursor de-velopment in the grapes prior to harvest, high acidity levels, andlack of yeast-contributed flavor compounds. Comparatively, ar-rested fermentation leaving high residual sugar levels in wines

Table 1–Technologies for reducing ethanol concentration inwine and fermented beverages (Duerr and Cuenat 1988;Pickering 2000; Smith 2002; Takacs and others 2007; Aguera andothers 2010).

Stage of wineproduction Principle Technology

Prefermentation Reduced fermentablesugars

Early fruit harvest

Juice dilutionGlucose oxidase enzyme

Concurrent withfermentation

Reduced alcoholproduction

Modified yeast strains

Arrested fermentationPostfermentation Membrane separation Reverse osmosis

PervaporationOsmotic distillation

Nonmembraneextraction

Solvent extraction

Ion exchangeSpinning cone column

may dictate that the finished product will require pasteurizationfor microbial stabilization, thereby leading to potential loss or al-teration of volatile flavor and aroma compounds. Adjusting vineleaf area to crop ratio is an interesting viticultural interventionfor moderating the concentration of fermentable carbohydrates inharvested wine grapes (Stoll and others 2009; Whiting 2010). Thispromising and emerging approach to managing grape sugar con-centrations attempts to address the imbalance between carbohy-drate accumulation and the development of sensorially importantgrape constituents. However, significant research is still requiredto determine the optimum leaf to crop ratios, timing, and loca-tion of leaf removal from the vines relative to fruit location and thelong-term impact upon vine physiology. Juice dilution can only beperformed using a low Brix grape adulterate, as addition of wateris not a permitted process for wine production. Low Brix grapejuice, a by-product of grape juice concentrate, is more commonlyused to maintain wine concentration during reverse osmosis orthermal distillation techniques for alcohol removal. Recent meth-ods that target prefermentation production strategies for reducingalcohol in wines have, therefore, focused upon technologies thatminimize loss or alteration of desirable organoleptic qualities andoff-flavor development. The use of enzyme technology for lower-ing the concentration of fermentable sugars in grape juice therebylimiting alcohol production prior to fermentation is one suchmethods and will form the basis of discussion for prefermentationproduction options in this article.

Glucose oxidaseBiochemical principle. GOX (EC 1.1.3.4) is an aerobic gly-

coprotein with dehydrogenase activity that catalyzes the oxida-tion of β-D-glucose to D-glucono-1,5-lactone (D-gluconic acidδ-lactone). This reaction requires the presence of molecular oxy-gen, and a flavin adenine dinucleotide cofactor to participate inelectron donation to form hydrogen peroxide. A 2nd enzyme,catalase, is frequently present in commercial GOX preparationsto degrade the unwanted peroxide that is formed as a by-productduring the oxidation of substrate. D-gluconic acid δ-lactone spon-taneously hydrates to form gluconic acid. The biochemical basisfor these reactions is shown in Figure 1.

Treatment of grape juice with GOX. As gluconic acid isnot fermented by yeasts, a decrease in alcohol production can beachieved in wines prepared from GOX-treated juice. The use ofGOX in wine was first described for rapid protection of winefrom dissolved oxygen (McLeod and Ough 1970; Ough 1975).The treatment of grape juice with GOX for lowering glucoseconcentration and consequently alcohol levels in finished wineswas explored and further refined (Heresztyn 1987; Villettaz 1987;Pickering and others 1999c). Glucose reduction in grape juice us-ing GOX is presently limited to white grape varieties, as a periodof clarification followed by enzyme reaction must first occur priorto yeast inoculation for fermentation to commence. As the glu-cose fraction in grape juice represents approximately 50% of totalfermentable sugars, the theoretical maximum reduction in alcoholproduction is 50%, compared to wines made from untreated juice.In practice, some inefficiency in glucose oxidation arises and re-ported alcohol reductions for wines produced using GOX-treatedjuice range from less than 4% to 40%. The efficiency of glucoseoxidation is dependent upon enzyme concentration, juice pH,dissolved oxygen concentration, processing time, and temperature(Pickering and others 1998; Pickering 2000).

Effect of pH on GOX. The most efficient conversion of glu-cose to gluconic acid in grape juice is reported to occur in a pH

R26 Journal of Food Science � Vol. 71, Nr. 1, 2012

R:Co

ncise

Revie

wsin

Food

Scien

ceTechnologies for reduced alcoholic wines . . .

range of 5.5 to 6.0 (Pickering and others 1998), correspondingto the reported pH range for optimum GOX activity (O’Neil2006). At the considerably lower grape juice pH range, the rateof gluconic acid production is reduced by up to 75% due to acidinhibition of enzyme activity. Deacidification of the juice withcalcium carbonate may, therefore, be required to ensure a suffi-cient reduction in glucose concentration to provide an adequatereduction of alcohol in the finished wine (Pickering and others1998). Catalase enzyme activity, required for efficient removal ofhydrogen peroxide, is present in most GOX preparations and isnot affected by the high acidity of grape juice. Indirect monitor-ing of glucose oxidation can be performed by determination ofpH and titratable acidity using standard wine laboratory techniques(Heresztyn 1987; Villettaz 1987).

Effect of oxygen on GOX. Molecular oxygen is an essen-tial requirement for GOX activity and must be sparged into thejuice during enzyme treatment. Agitation will assist dispersion ofoxygen bubbles, and enhance GOX activity, probably by limitingbubble size and maximizing bubble surface area to volume ratios,thereby increasing dissolved oxygen concentrations. Little infor-mation is available that describes the optimum dissolved oxygenconcentration for GOX treatment of grape juice. Different ratesof air sparging, bubble size, sparger design, and mixing rates areimportant considerations that influence the rate of gluconic acidproduction (Pickering and others 1998). Problems with exces-sive foaming and evaporation have also been reported with highaeration levels (Heresztyn 1987). The sparging of the juice duringglucose oxidation, and peroxide formation during the oxidation ofglucose, will also result in oxidation of polyphenolic constituents ofthe grape juice and development of a brown color (Villettaz 1987).Oxidized phenolics do precipitate during fermentation and con-sequently the resulting wine is reported to have a more developedgolden yellow color than wines produced with reductively han-dled juice. GOX wines do have less susceptibility to browning and“pinking” color reactions during short- to medium-term storagethan control wines (Pickering and others 1999b). Loss of grapevolatile precursors and components may also potentially arise fromair or oxygen sparging at excessive rates for prolonged periods.

Effect of temperature on GOX. Reports on optimal tem-perature for GOX activity are ambiguous. Early experiments withgrape juice demonstrated more rapid glucose oxidation occurringat a temperature of 20 ◦C compared to 30 ◦C (Heresztyn 1987).This contrasts with the reported temperature optimum for GOX

activity between 30 and 35 ◦C (O’Neil 2006), while other reportshave not demonstrated any significant difference in gluconic acidproduction rates in GOX-treated juice at temperatures of 20 and30 ◦C (Pickering and others 1998). Several advantages are appar-ent for lower processing temperatures. Higher dissolved oxygenlevels in the juice can be achieved at lower temperatures and oxy-gen concentration is an important rate limiting reactant for GOXactivity. Undesirable microbial growth may also be decreased at20 ◦C, although many wine spoilage organisms are quite capableof growth at this temperature.

GOX produced wines and their composition. A sum-mary of glucose reduction, gluconic acid concentrations, winecomposition, and resulting alcohol reduction in juice and winesarising from GOX treatment is given in Table 2 and 3. The com-position of GOX and control wines prepared from deacidifiedgrape juices is also given in Table 4. High levels of gluconic acidproduced from conversion of the glucose fraction of fermentablesugars is a significant problem for finished wine composition. Thecontribution of gluconic acid to total acidity in wines prepared byGOX-treated juice may render the wines out of balance (Pickeringand others 1999b). To moderate this problem, and to optimize

Table 2–Glucose oxidation rates in grape juice and alcohol redu-ction percentages in corresponding wine made from glucoseoxidase-treated grape juice (Heresztyn 1987; Villettaz 1987;Pickering and others 1999c).

Glucoseoxidase/catalase Glucose Gluconic Alcohol

Grape concentration reduction acid reductionvariety (mg/L) (%) (g/L) (%)

Chasselas 500 NS NS 23Muller-

Thurgau2000 87 73 40

MuscatGordoBlanco

50 13 11 3.6

MuscatGordoBlanco

200 31 25 13

MuscatGordoBlanco

1000 56 53 33

Riesling 500 36 10 to 52 23Riesling 2000 NS NS 36

NS = not stated.

Figure 1–Biochemical oxidation of β-D-glucose to D-glucono-1,5-lactone (gluconic acid δ-lactone) by glucose oxidase and subsequent hydration togluconic acid. Catalase enzyme degrades the hydrogen peroxide formed during glucose oxidation (Hartmeier and Willcox 1981).

Vol. 71, Nr. 1, 2012 � Journal of Food Science R27



GOX activity, deacidification of the grape juice with calciumcarbonate prior to GOX treatment may be necessary. A typicalscheme for the production of reduced alcohol wine by GOX treat-ment of white grape juice is shown in Figure 2. A particular issueassociated with the production of wines from GOX-treated grapejuice is the formation of substantial quantities of carbonyl com-pounds, resulting in significantly higher sulphur dioxide bindingthan in control wines (Pickering and others 2001). Consequently,the total concentration of sulphur dioxide necessary to achievemicrobial stabilization in GOX wines may approach or even ex-ceed legal limits (Pickering and others 1999a). A further deleteri-ous outcome of GOX treatment is an increased susceptibility forthese wines to undergo premature browning consistent with in-creased flavonoid production (Pickering and others 1999a, 1999b,1999c).

Fermentation Technologies for Limiting AlcoholProduction

Use of novel yeast strainsSelection of specific yeast strains and their use as starter cul-

tures for the consistent manufacture of a wine style is a com-mon winemaking practice. The use of specific yeast strains forwine production also ensures improved fermentation reliability and

predictability than reliance upon natural fermentation (Pretorius2000). A difficulty faced by some winemakers and viticulturists isthe production of wine grapes that have a balance between flavorcomponents and accumulated sugar. The requirement for someproducers to harvest grapes at high levels of fermentable sugar toachieve typical varietal characters produces wines with excessivealcohol concentrations and undesirable palate hotness (de BarrosLopes and others 2000). One strategy to overcome the excessiveproduction of alcohol in these wines is the selection of yeast strainswith lowered ethanol production during fermentation. Some vari-ability in ethanol production by different commercially availablewine starter cultures of Saccharomyces cerevisiae has been described;however, the difference in final ethanol concentrations determinedin one controlled experiment was less than 1% v/v (Jenson 1997).The selection of yeasts other than S. cerevisiae with lower ethanolproduction rates for grape juice fermentation is possible. Low al-cohol wines produced by the fermentation of oxidized grape juiceusing strains of Pichia and Williopsis were demonstrated to have anacceptable, albeit different palate structure and organoleptic qual-ities, than wines produced with S. cerevisiae (Erten and Campbell2001). A problem of fermentation using novel or wild yeast speciesis potential off-flavor development and undesirable organolepticcharacters (Heard 1999), hence the development of geneticallymodified Saccharomyces strains for wine production.

Table 3–Glucose oxidase/catalase treated Chasselas juice and reduced alcohol wine production (Villettaz 1987).

Wine analysis Wine analysisafter alcoholic after malolactic

Treatment Juice analysis fermentation fermentation

Glucose oxidase/ catalase Contact Titratable Titratable Titratable Alcohol Alcoholconcentration (mg/L) time hours pH acidity (g/L)† pH acidity (g/L)† pH acidity (g/L)† (% v/v) reduction (%)

0 0 3.63 6.0 3.57 6.0 3.75 3.8 11.150 2.0 3.40 7.0 3.37 6.8 3.60 4.9 10.1 9100 2.0 3.31 8.05 3.30 8.0 3.50 6.0 10.0 10500 2.25 3.20 10.25 3.25 9.2 3.40 7.0 10.0 10500 15.0 2.84 19.7 3.00 16.1 3.09 13.3 8.5 23†As tartaric acid.

Table 4–Composition of Muller-Thurgau and Riesling wines prepared from GOX-treated deacidified juice (Pickering and others1999a, 1999b).

Deacidified GOX-treated Control DecreasedComponent juice juice juice alcohol wine§ Control wine§

Muller-ThuragauEthanol % v/v 6.2 10.5Glucose g/L 84.7 10.7 84.7 <1.0 <1.0Fructose g/L 89.8 87.2 89.8 <1.0 <1.0Gluconic acid g/L <0.3 72.7 <0.3 66.7 <0.3Tartaric acid g/L 1.9 1.7 4.3 1.8 2.9Titratable acidity† g/L 3.2 26.7 7.1 27.8 8.1pH 4.89 2.93 3.25 3.05 3.13

RieslingEthanol % v/v 6.5 10.2Brix ◦ 18.1Titratable acidity† g/L 2.7 22.7 10.8 22.6 10.7pH 5.49 3.07 3.08 3.05 2.95Total flavonoids‡ a.u. 1.77 3.89 1.93 2.49 1.65Total hydroxycinnamates‡¶ mg/L 95.67 72.8 96.6 57.8 82.2A420 0.15 0.33 0.14 0.17 0.08A520 0.028 0.075 0.033 0.030 0.017Free SO2 43 39Bound SO2 241 170Total SO2 284 209

§Analysis at time of bottling.†As tartaric acid.‡Corrected for gluconic acid/lactone.¶Caffeic acid equivalents.


R:Co

ncise

Revie

wsin

Food

Scien


Genetically engineered S. cerevisiaeThe potential to engineer specific yeast strains of S. cerevisiae

that divert grape carbon compounds from ethanol to productionof other metabolites, or increasing biomass has been identifiedas a strategy to decrease the final ethanol concentration of wines(Bartowsky and others 1997). A number of gene products thatinteract with the glycolytic pathway and associated biochemicalpathways involved in redox balance have been targeted.

Early work with single gene mutations to isoenzymes of al-cohol dehydrogenase (Drewke and others 1990) or triose phos-phate isomerase at low glucose concentrations in aerated cultures(Compagno and others 1996, 2001) enabled higher levels of glyc-erol to be formed. However, culture conditions in these experi-ments were significantly different to a typical grape juice or must

fermentation, and therefore results should be interpreted withcaution. Nonetheless, these early experiments were important inidentifying specific metabolic pathways with potential to redi-rect carbon flux from ethanol synthesis, and the development ofmethods for genetic manipulations of the genes encoding specificenzymes of interest in wine yeast strains.

More recently, cofactor engineering has been used to modifyredox balance within the yeast cell and thereby altering the flux ofcarbon through a suite of pathways (Geertman and others 2006;Heux and others 2006a, 2006b; Hou and others 2009). Trans-genic incorporation of water soluble (cytosolic) oxygen-dependantnicotinamide adenine dinucleotide hydride (NADH) oxidase en-zymes expressed during yeast growth show some promise in mod-ulating ethanol production, while maintaining redox balance and

Figure 2–Processing scheme for production ofreduced alcohol wines using glucose oxidase.




avoiding unwanted accumulation of sensorially active compoundsas carbon flux is redirected through multiple pathways. A signif-icant disadvantage of cofactor engineering is the requirement forsoluble oxygen to be supplied during fermentation and currentinvestigations involve the utilization of relatively low carbohydrateconcentrations relative to grape juice or must.

Most effort in recombinant technologies for manipulation ofwine yeasts has targeted increasing glycerol production at the ex-pense of ethanol and has required multiple gene modifications(Nevoigt and Stahl 1996; Michnick and others 1997; de BarrosLopes and others 2000; Geertman and others 2006). Between4% and 10% of grape juice carbon is normally directed to glycerolproduction during fermentation by S. cerevisiae with the major-ity being produced during the initial stages of biomass formation(Scanes and others 1998; Ribereau-Gayon and others 2006). Thefinal concentration of glycerol in finished dry wines normallyranges between 4 and 9 g/L and is dependent upon the yeaststrain and a range of environmental signals including temperature,pH, sugar concentration, nitrogen source, and sulphur dioxide lev-els (Scanes and others 1998; Remize and others 1999). The majorbenefits of glycerol formation for yeast cells during fermentationare 2-fold. Glycerol is normally produced by S. cerevisiae duringbiomass formation at commencement of fermentation to protectcells from the high osmolar concentrations of sugars, thereby pre-venting cellular dehydration. Also, as the reactions for glycerolformation involve oxidation of NADH, the redox imbalance thatarises from anaerobic glycolysis and glucose repression of respi-ration is corrected (Scanes and others 1998). It is the correctionof redox balance that is considered the most important biologicalfunction of glycerol formation (Michnick and others 1997).

Glycerol formation arises from reduction of the glycolytic in-termediate dihydroxyacetone-phosphate to glycerol-3-phosphateand subsequent dephosphorylation. These 2 reactions are cat-alyzed by an NADH-dependent glycerol-3-phosphate dehydro-genase (GPDH) and a specific glycerol-3-phosphatase (GPP),respectively. Two isoforms of GPDH have been described anddesignated GPDH-1 and GPDH-2 with expression of the genesencoding these isoenzymes regulated by the yeast requirement forosmoprotection and redox balance, respectively (Michnick andothers 1997). Osmoprotection in the early stages of fermenta-tion by upregulated GPDH-1 expression has been shown to havea more significant role in glycerol production than correctionof redox imbalance by GPDH-2 during anaerobic fermentation(Remize and others 2003).

As glycerol and ethanol production by yeasts during fermenta-tion are important regulators of cellular redox balance through theregeneration of NAD+, any influence upon the flux of these com-pounds will alter the concentration of a range of other metabolitesthat are also involved with redox balance. Acetaldehyde, acetate,succinate, acetoin, diacetly, and 2,3-butandiol appear to be themost important of these metabolites (Michnick and others 1997;Remize and others 2000; Taherzadeh and others 2002; Cambonand others 2006; Ehsani and others 2009). The presence of thesecompounds in wine at levels exceeding their sensory thresholdmay be detrimental to perceived wine quality (Boidron and others1988; Etievant 1991).

Genetic manipulation of yeast strains to overexpress eitherGPDH-1 or GPDH-2 has resulted in diminished ethanol of be-tween 19% and 22% in model solutions but significantly lessin grape juice fermentations. Concomitant with increased glyc-erol formation and decreased ethanol production was increasedin acetate, succinate, acetoin, acetaldehyde, and 2, 3-butandiol

(Michnick and others 1997; Remize and others 1999; de BarrosLopes and others 2000; Cambon and others 2006). Acetate forma-tion by yeasts during fermentation may occur either by hydrolysisof acetyl-CoA or the pyruvate dehydrogenase (PDH) bypass path-way in which pyruvate is decarboxylated to acetaldehyde followedby oxidation to acetate (Remize and others 2000; Ribereau-Gayonand others 2006). The enzymes involved in the PDH bypass arepyruvate decarboxylase (PDC) and an acetaldehyde dehydroge-nase that belongs to the aldehyde dehydrogenase (ALD) group ofenzymes. The ALD group of enzymes in S. cerevisiae has beenextensively characterized with 5 isoforms (ALD2-6) being desig-nated, and the most important of these during fermentation areALD-5 (mitochondrial) and ALD-6 (cytosolic) as both are con-stitutive enzymes. The expression of isoforms ALD2-4 is glucoserepressed and therefore these enzymes do not play any role in cellu-lar redox balance during grape juice fermentation (Navarro-Avinoand others 1999).

Saccharomyces cerevisiae strains with a downregulated PDC geneand overexpressed GPDH-1 were developed to enhance glycerolproduction at the expense of ethanol (Nevoigt and Stahl 1996).PDC activity was reduced to less than one fifth of wild type andGPD-1 overexpression resulted in a 45% reduction in ethanol;however, the end products, acetate and acetaldehyde derived fromalternate redox reactions, were subsequently increased (Nevoigtand Stahl 1996).

A novel method to overcome the deleterious effects of highacetate levels in fermentation conducted by GPDH-2 overex-pressing yeasts has been developed. By using a yeast strain withan acetaldehyde dehydrogenase-6 (ALD-6) gene deletion, a sub-stantially lower ethanol and acceptable acetate concentration wasdemonstrated (Eglinton and others 2002). However, the concen-tration of other sensorially important metabolites, such as acetalde-hyde and acetoin, were significantly in excess of concentrationsconsidered to be acceptable for wine products. Further gene ma-nipulations of S. cerevisiae were developed that included overex-pressed 2, 3-butanediol dehydrogenase (BDH) (Ehsani and oth-ers 2009), an NADH-dependant reductase responsible for theconversion of (3R)-acetoin, and (3S)-acetoin to (2R, 3R)-2, 3-butanediol and meso-2-3,butanediol, respectively (Gonzalez andothers 2000). A summary of metabolite concentrations involvedin cellular redox balance using genetically modified yeast strainstargeting GPDH, ALD, and BDH expression is presented in Table5 and important biochemicals involved in their formation is shownin Figure 3. Clearly, any attempt to redirect carbon flux by genemanipulations causes numerous biochemical pathway interactions.Consequently, redox imbalance within the cell must be corrected,and arising from alternate biochemical pathway modulation is theproduction of a suite of sensorially important compounds that mayexceed desirable organoleptic concentrations in wine.

Further limitations of gene technology for yeast strainmanipulations

While genetic engineering has shown significant promise as atechnology to enable selection of yeast strains specifically tailoredfor expression of desirable traits, a number of barriers to the up-take of this technology for regular wine production are apparent.Controlling the flux of metabolic intermediates and end prod-ucts not specifically targeted by genetic manipulations in yeaststrains remains an important barrier that, while not insurmount-able, must be controlled in order to achieve commercial productsthat are organoleptically acceptable. Deletion or overexpressionof one gene product can significantly alter a suite of metabolic


R:Co

ncise

Revie

wsin

Food

Scien


Tab

le5–

Chan

ges

inm

etab

olite

conce

ntr

atio

ns

of

yeas

tcu

lture

sw

ith

modifi

edgen

eex

pre

ssio

nfo

rgly

cero

lpro

duct

ion.

Conce

ntr

atio

nofm

etab

olite

s

Yea

stst

rain

Modifi

edge

ne

Eth

anolre

duct

ion

Eth

anol

Gly

cero

lA

ceta

teSucc

inat

eA

ceto

in2,

3-buta

ned

iol

Ace

tald

ehyd

edes

ignat

ion

pro

duct

expre

ssio

nG

row

thm

edia

%g/

Lg/L

g/L

g/L

g/L

g/L

mg/

L

Nev

oigt

and

Stah

l(19

96)†

Glu

cose

18g/

LW

ildty

peC

ontr

ol7.

90.

60.

20N

SN

SN

S<

5G

PD-1

GPD

H-1

over

expr

esse

d35

5.1

4.1

0.58

NS

NS

NS

361

pdc

PDC

dow

nreg

ulat

ed29

5.6

2.9

0.29

NS

NS

NS

<5

pdc

GPD

-1PD

Cdo

wn

regu

late

dG

PDH

-1ov

erex

pres

sed

454.

35.

10.

40N

SN

SN

S<

5

Mic

hnic

kan

dot

hers

(199

7)G

luco

se10

0g/

L,pH

3.3

V5/

pVT

UC

ontr

olst

rain

46.8

4.3

NS

NS

NS

NS

NS

GPD

1V

5/G

PD1

GPD

H-1

over

expr

esse

d22

36.6

14.0

NS

NS

NS

NS

NS

V5/

pVT

UC

ontr

olst

rain

Glu

cose

200

g/L,

pH3.

389

.27.

10.

520.

25<

0.1

0.90

<10

0G

PD1

V5/

GPD

1G

PDH

-1ov

erex

pres

sed

1972

.528

.61.

600.

546.

101.

3022

0

Rem

ize

and

othe

rs(1

999)

Glu

cose

200

g/L

pvt1

00-U

-ZE

OR

Con

trol

stra

in88

.47.

40.

420.

400.

000.

240.

01pv

t100

-U-Z

EO

-GPD

1R

GPD

H-1

over

expr

esse

d3

85.7

16.5

1.18

1.11

0.06

1.92

0.04

deB

arro

sLo

pes

and

othe

rs(2

000)

Cha

rdon

nay

juic

e21

.8◦ B

rix,

pH3.

16A

WR

I83

8C

ontr

olst

rain

129.

87.

90.

580.

39N

SN

SN

SA

WR

I83

8G

PD2-

OP

GPD

H-2

over

expr

esse

d4

124.

016

.51.

020.

65N

SN

SN

SE

glin

ton

and

othe

rs(2

002)

Glu

cose

80g/

LG

PD2

ALD

6C

ontr

olst

rain

34.1

5.1

0.66

0.59

NS

NS

0.64

GPD

2-O

PA

LD6

GPD

H-2

over

expr

esse

dA

LD6

norm

alex

pres

sion

2426

.013

.41.

420.

83N

SN

S8.

36

GPD

2al

d6�

GPD

H-2

norm

alex

pres

sion

ALD

6de

letio

n

931

.16.

00.

200.

59N

SN

S0.

79

GPD

2-O

Pal

d6�

GPD

H-2

over

expr

esse

dA

LD6

dele

tion

2027

.316

.30.

360.

88N

SN

S8.

79

Cam

bon

and

othe

rs(2

006)

Glu

cose

200

g/L;

mal

ican

dci

tric

acid

6g/

L;Y

AN

460

mg/

LV

L1C

ontr

olst

rain

97.2

6.5

0.57

0.31

NS

1.14

16V

L1al

d6A

LD6

dele

tion

<1

96.6

7.4

0.19

0.29

NS

1.30

8V

L1G

PD1

GPD

H-1

over

expr

esse

d17

80.2

24.4

2.64

0.48

5.4

4.01

105

VL1

GPD

1al

d6G

PDH

-1ov

erex

pres

sed

ALD

6de

letio

n23

74.7

26.8

0.62

0.62

6.2

6.05

182

K1M

Con

trol

stra

in93

.35.

80.

380.

31N

S0.

6139

K1M

ald6

ALD

6de

letio

n93

.66.

80.

100.

43N

S0.

5218

K1M

GPD

1G

PDH

-1ov

erex

pres

sed

1182

.618

.20.

980.

784.

24.

8518

3K

1MG

PD1

ald6

GPD

H-1

over

expr

esse

dA

LD6

dele

tion

1678

.821

.90.

430.

885.

83.

9322

8

(Con

tinue

d)




Tab

le5–

Conti

nued

Conce

ntr

atio

nofm

etab

olite

s

Yea

stst

rain

Modifi

edge

ne

Eth

anolre

duct

ion

Eth

anol

Gly

cero

lA

ceta

teSucc

inat

eA

ceto

in2,

3-buta

ned

iol

Ace

tald

ehyd

edes

ignat

ion

pro

duct

expre

ssio

nG

row

thm

edia

%g/

Lg/L

g/L

g/L

g/L

g/L

mg/

L

BC

Con

trol

stra

in92

.47.

20.

380.

37N

S1.

459

BC

ald6

ALD

6de

letio

n2

90.4

7.1

0.05

0.64

NS

0.99

10B

CG

PD1

GPD

H-1

over

expr

esse

d10

82.7

16.5

1.36

0.58

2.9

3.9

95B

CG

PD1

ald6

GPD

H-1

over

expr

esse

dA

LD6

dele

tion

1875

.526

.90.

500.

749.

55.

0932

0

Ehs

ania

ndot

hers

(200

9)G

luco

se24

0g/

LV

5C

ontr

olst

rain

118

70.

630.

40.

00.

910

V5

ald6

ALD

6de

letio

n<

111

79

0.14

0.5

0.0

1.3

10V

5al

d6G

PD1

GPD

H-1

over

expr

esse

dA

LD6

dele

tion

1699

320.

650.

95.

92.

514

0

V5

ald6

GPD

1B

DH

1G

PDH

-1an

dB

DH

-1ov

erex

pres

sed

ALD

6de

letio

n

1798

300.

700.

90.

58.

012

0

V5

ald6

GPD

1B

DH

1 221

,222

,223

GPD

H-1

and

BD

H-1

over

expr

esse

dA

LD6

dele

tion

1897

320.

650.

90.

67.

412

0

† Con

vert

edfr

omm

mol

/L.

PDC

=py

ruva

tede

carb

oxyl

ase

gene

;G

PDH

-1=

glyc

erol

-3-p

hosp

hate

dehy

drog

enas

e1

gene

;G

PDH

-2=

glyc

erol

-3-p

hosp

hate

dehy

drog

enas

e2

gene

;A

LD6

=ac

etal

dehy

dede

hydr

ogen

ase

6ge

ne;

BD

H1

=(2

R,3

R)-

2,3-

buta

nedi

olde

hydr

ogen

ase;

NS

=no

tst

ated

.

intermediates and end products during fermentation as the ma-nipulated yeast cells attempt to compensate altered metabolism.Some metabolic traits are encoded by a suite of genes or theinteraction of several gene systems on different chromosomeswithin the yeast genome (Pretorius 2000). Achieving desirableoenological outcomes by genetic engineering may therefore notbe possible with approaches targeting a limited number of genes.A complicating factor in genetic manipulations of wine yeast isthe failure of some transgenic strains to complete fermentation ina timely manner (Remize and others 2000; Remize and others2003; Heux and others 2006b).

Some of the gene inserts used to induce overexpressed geneproducts may not be stable within the altered strain. A significantdisadvantage is the loss of the plasmid insert from yeast cells dur-ing fermentation (Remize and others 1999; de Barros Lopes andothers 2000). Thus, incorporation of stable plasmid inserts con-taining overexpressed genes, or gene deletions limiting the pro-duction of specific enzymes that alter metabolic flux, must beachieved in order to produce consistent and reliable fermentationswith these yeasts. Most importantly, however, is the attitude ofconsumers to foods that contain or produced using geneticallymodified organisms (GMOs). The use of GMOs in food productsis a major cause of concern and mistrust among consumers and hasled to the introduction of some trading restrictions of these goodsbetween economic zones, labeling requirements stating the useof GMOs in food production, and, in some instances, the refusalby retailers to stock products that cannot be proven to be free ofGMOs or their metabolic products (Burton and others 2001). Apossible future use of gene technology in the wine industry will bethe identification and comparison of fermentation performance ofyeast strains traits bred by selective breeding techniques.

Postfermentation Technologies for Removing Alcohol

Membrane transport processesThe removal of ethanol from wine following the completion

of fermentation can be achieved either through the applicationof thermal distillation processes, with or without vacuum, or thetransport of ethanol across a semi-permeable barrier or membrane.Various technologies in which a membrane is used for the selec-tive removal of ethanol from beverages have been developed thatrely upon molecular permeation of ethanol from the feed stockwith high concentration, to a stripping phase with low concen-tration. The most prevalent membrane-based technology for theremoval of organic constituents from beverages is reverse osmo-sis, and emerging technologies, such as osmotic distillation andpervaporation, are still nonmainstream.

Reverse osmosis. The separation of 2 solutions of unequalsolute concentration by a semi-permeable membrane establishesa concentration or pressure gradient between them known asosmotic pressure. In such a system, water will move by a pro-cess of osmosis from the solution of low concentration across themembrane in order to restore equilibrium. However, if sufficientpressure (greater than the osmotic pressure) is applied on the highconcentration side, solvent can move out of this solution across themembrane to the low concentration solution, in a phenomenonknown as reverse osmosis. Effectively, the concentration of thedilute solution reduces while that of the concentrated solutionincreases.

From the explanation outlined above, it should be easy to seehow this phenomenon could be exploited as a filtration pro-cess. In fact, simply adjusting the pore size of the membrane


R:Co

ncise

Revie

wsin

Food

Scien


Figure 3–Biochemical pathways and specific enzymes targeted for modulating carbon flux and ethanol production in Saccharomyces cereivisiae. TPI =triose phosphate isomerise; GPDH = glycerol-3-phosphate dehydrogenase; GPP = glycerol-3-phosphatase; ADH = alcohol dehydrogenase; PDC =pyruvate decarboxylase; ALS = acetolactate synthase; ALD = acetaldehyde dehydrogenase; PDH = pyruvate dehydrogenase; DS = diacetyl synthase;BDH = 2,3-butanediol dehydrogenase; DR = diacetyl reductase. Modified from Remize and others 2000, Ribereau-Gayon and others 2006, Cordier andothers 2007, Ehsani and others 2009.

Figure 4–Separation capabilities of different membrane systems showing typical operating pressure (in parentheses). RO = reverse osmosis; NF =nanofiltration; UF = ultrafiltration; MF = microfiltration.




material and the applied pressure give rise to a spectrum of mem-brane filtration processes with increasing solute permeability (andreducing operating pressure) such as reverse osmosis, nanofiltra-tion, ultrafiltration, and microfiltration, respectively (Figure 4).Thus, not only water or substances with comparably low molec-ular weight may pass through the membrane as in reverse osmosisbut other solutes and solvents in gradation of size and molecularweights.

During membrane processing, the feed is separated into2 streams: retentate (concentrate) and permeate (filtrate). The vol-umetric throughput of the membrane surface per hour, per metersquare (L h−1 m−2) is called the flux and is dependent on theapplied pressure and total membrane resistance. The membraneresistance is a composite of factors that limit permeation such asviscosity of permeate, pore size, extent of fouling, and interactionsbetween membrane material and feed. The larger the membranearea, the greater the filtration capacity.

The first patent for the application of reverse osmosis in al-coholic beverages was obtained by the West German brewingcompany Lowenbrau in 1975 for the dealcoholization of beer andwine (Meier 1992). Other applications of reverse osmosis in wineproduction include removal of colors and flavors, must concen-tration (as an alternative to chaptalization), development of newproducts such as aperitifs, wine stabilization against tartrate pre-cipitation and deacidification (removal of volatile acids) of grapejuices (Baldwin 1998; Smith 2002).

As a membrane technology, reverse osmosis requires low-energyinput, operates at ambient temperatures, allows reproducible con-trol over separations, requires no disposable filtration media orother additions, and is easily automated for continuous operation(Gibson 1986). Specifically, in comparison to other methods ofproducing low alcohol wines such as distillation, spinning conetechnology or arrested fermentation, the reduced alcohol winesproduced by reverse osmosis usually have flavor and aroma profilecomparable to the regular wines from which they were obtained(Bui and others 1986) as no phase change is associated with theprocess, and water and alcohol are largely the only componentsremoved from the feedstock.

Membrane types and configurations. Reverse osmosis membranes canbe made of several different materials including cellulose acetate,regenerated cellulose, synthetic polymers, and ceramics (Heldmanand Hartel 1997; Westbrook 1989). The cellulosic materials are notas durable and give low flux rates compared to the synthetic poly-mers, which are also more selective. Ceramics, while very strongand durable, are also expensive, being designed originally for sep-aration of uranium isotopes (Gibson 1986). The most successfulmembranes are the asymmetric (heterogenous) types, which arethin skins of membrane material bonded to one or more lay-ers of polymeric support material to create a composite mem-brane configuration (Figure 5). Thin-film composite membranesare very commonly used where a polymer with high strengthand porous structure is chemically bonded to a very thin film ofpolymer (membrane material) with the required permeation se-lectivity. Such membranes give good flux characteristics and arevery durable under the high-pressure application of reverse osmo-sis. These membranes are also cleanable and allow back flushing torestore initial flux rates by destabilizing any build up of materialson the membrane surface.

Reverse osmosis, such as other membrane techniques, operatesunder the principle of cross or tangential flow, whereby the liq-uid flows parallel or tangential to the membrane surface at high

velocity under pressure. Some liquid passes through the membranebut the solids or materials with molecular weight higher than thenominal molecular weight cutoff (NMWCO) of the membranewill be swept along in the stream of feed across the membrane.Recycling will ensure that more permeate will pass through themembrane during each cycle until the desired concentration ofthe feed is achieved. In order to effectively do this, several moduleconfigurations have been developed. These include the flat sheet(also known as plate and frame), tubular, hollow fiber, and spiralwound configurations. The spiral wound configuration makes themost economic use of space for a given membrane area, beingflat membranes rolled up together like a cigar (Pretorius 2000).The original space between the membranes serve as permeatecollection channels and the new space generated from windingthe membranes becomes the feed channel.

Applications and limitations. In a reverse osmosis process for alco-hol reduction in wines, the feed is the regular wine with normalalcohol content. This wine is pumped at pressures up to 4 MPa(40 atm) through a membrane module and such pressures can re-sult in elevated temperatures at the membrane surface. To avoidexcessive temperature arising from high pressures, heat exchangersare typically a component of the apparatus with operating tem-peratures around 20 to 22 ◦C (Smith 1996). Operating conditionsmust be balanced between gaining efficiencies in permeate fluxat higher pressures and aroma retention, which is improved atlower temperatures (Catarino and others 2007; Labanda and oth-ers 2009). A membrane is selected with a low NMWCO, typically<200 Da (Catarino and others 2007) so that water and ethanol,being small molecules, pass through the membrane into the per-meate stream. The retentate is redirected to the feed tank and

Figure 5–Schematic of a typical asymmetric composite membrane showing:(1) thin skin of porous membrane; (2) polymeric micro-porous support; and(3) polyester support.


R:Co

ncise

Revie

wsin

Food

Scien


the wine is continuously dealcoholized and concentrated (Duerrand Cuenat 1988; Meier 1992). Wine is restored to the originalwater content by the addition of low Brix juice, a by-productof grape juice concentrate. Alternatively, low Brix juice may becontinuously added to the feed (wine) to keep the volume con-stant during the process. Basically, the more low Brix juice added,the lower the alcohol content in the feed tank. This also hasthe effect of increasing permeation since the osmotic pressure isalso reduced. The simultaneous production of low Brix juice oralcohol-enriched wine, with dealcoholized wine is possible byusing 2 reverse osmosis units in parallel, one with an ethanol im-permeable membrane and redirecting the filtrate from this unitto the feed supplying the ethanol permeable unit (Bui and others1986). More commonly, rectification of the permeate, to separate

ethanol and the water content is possible using thermal distillationprocesses and redirecting the water component back to the feedtank in a closed-loop system maintains wine volume without therequirement for low Brix juice addition. Such apparatus are nowcommonly used for ethanol removal from wine products (Smith1996) and a typical process within a closed-loop system is shownin Figure 6. Reverse osmosis can be used to reduce alcohol con-tent in wine from about 12% to 15% v/v to less than 0.5 % v/v,producing a wide range of low alcohol wines, thereby allowingproduction flexibility.

In comparison to other conventional methods of dealcoholiza-tion or preparation of low alcohol wines, the capital cost of reverseosmosis is higher and at removal of ethanol to below 0.45% v/vconsumes more electricity per liter of ethanol removed (Pilipovik

Figure 6–Schematic for dealcoholization of wine using a closed-loop reverse osmosis process. Wine is pumped under high pressure (1) through asemi-permeable membrane (2), and is separated into 2 streams, permeate (3) and retentate (4). A rectification column (5) is used to thermally distilthe permeate with the water (6) added back to the wine and ethanol (7) collected as a by-product.

Figure 7–Basic principle of ethanol removal by vapor pressure differential across a semi permeable membrane. Osmotic distillation employs a strippingphase of degassed pure water: pervaporation uses an inert gas with water vapor. Ethanol migrates through the membrane in a gaseous phase andrecondenses within the stripping phase as permeate. Adapted from Hogan and others 1998.




and Riverol 2005). However, labor and other operating costs arelow, especially since energy is used more efficiently. Savings onoperating costs would also depend on the plant capacity. Reverseosmosis, as part of the family of membrane filtration techniques, isalready being employed for improving efficiency and maintainingviability of the wine industry. Apart from dealcoholization, otherpossible uses in the wine industry include amelioration of wine,treatment of saline water for irrigation, and treatment of waste wa-ter to reduce costs of waste disposal. Each process requires slightlydifferent configuration of equipment and various changes to theprocessing of permeate.

Emerging membrane technologies: osmotic distillationand pervaporation. Osmotic distillation, also referred to asevaporative pertraction or isothermal membrane distillation(Diban and others 2008) and pervaporation share similar processesin that selective removal of ethanol, arises from the establishmentof a vapor pressure differential across a membrane, which usu-ally has hydrophobic properties. Thus, ethanol removal occurs asa process of evaporation at the wine membrane interface, diffu-sion of the vapor across the membrane, and condensation into thestripping phase.

The nature of the stripping phase determines the process; os-motic distillation employs degassed pure water (Hogan and others1998; Diban and others 2008), whereas pervaporation makes use ofan inert gas containing water vapor (Karlsson and Tragardh 1996;Takacs and others 2007). The basic principles of ethanol removalfrom wine by establishing a vapor differential are illustrated inFigure 7. Osmotic distillation membranes have hydrophobic, apo-lar, properties, which are essential as this critical factor determinesthe flux of ethanol from retentate to permeate. Aroma and fla-vor components have lower vapor pressures in ethanolic solutionsthan ethanol itself; thus, the flux ratios of these compounds areconsiderably lower and are mostly retained within the wine. Mem-branes used for osmotic distillation are usually constructed frompolyethylene, polypropylene, polytetrafluoroethylene, or polyvinyldifluorides in varying pore sizes. Compared to reverse osmosis,ethanol flux is considerably lower and thus longer times are re-quired for the equivalent ethanol removal; however, energy savingsarise from the considerably lower pressures and product integrityimproved from lower operating temperatures (Varavuth and others2009). As the vapor pressure differential across the membrane foraroma compounds is generally much lower than ethanol, the fluxand subsequent aroma losses of important flavor compounds areminimized. In a pilot-scale operation, 2 % v/v of ethanol was re-moved from a merlot wine and the loss of compounds, consideredimportant to wine flavour, to the permeate varied from 0.9% to98% (Diban and others 2008). Compound losses were attributedto the polarity and volatility of the compound and therefore in-creased with residency time for treatment, thus potentially limitingethanol removal. Difference testing with untrained panels couldnot detect significant differences between the wines at 13.35 % and11.3% v/v illustrating the potential for the use of osmotic distilla-tion for the removal of small fractions of alcohol from beverages.

Pervaporation technologies for ethanol removal have not beenas widely adopted as osmotic distillation or reverse osmosis, andfew reports in the literature describe the use of this technologyfor the treatment of wine. This may possibly be attributed tohigher temperatures required to achieve effective ethanol per-meation compared to osmotic distillation as temperature ele-vation will also increase the flux of aroma compounds to thepermeate (Takacs and others 2007). One report in which a hy-drophilic membrane was employed for ethanol reduction to a

final concentration of 0.5% v/v in chardonnay resulted in the re-tention of 80% of the concentration of most aroma compounds(Karlsson and Tragardh 1996). Clearly, further research is requiredand the retention of aroma compounds improved, before perva-poration becomes more widely adopted for moderation of ethanolin beverages.

Spinning cone columnsThe spinning cone column (SCC) is a device used to extract

volatile flavor components from a liquid or slurry. The columnconsists of a vertical shaft rotating at approximately 350 rpm, sup-porting up to 22 inverted (pointing downwards) cones. Betweeneach pair of cones, there is a fixed inverted cone, attached to thecasing of the column (Figure 8). The liquid feed is fed to the topof the column into the 1st spinning cone. A film of liquid is flung

Figure 8–Mechanical layout of the spinning cone column (SCC). 1: productin; 2: product out; 3: gas in; 4: gas out; 5: rotating shaft; 6: stationary cones;7: rotating cones. Courtesy Flavourtech, Lenehan Rd., Griffith, Australia.


R:Co

ncise

Revie

wsin

Food

Scien


outwards by centrifugal action onto the inside surface of the cas-ing. The liquid will then drop onto a fixed cone and migrate as athin film downwards and toward the center of the cone under theinfluence of gravity. The liquid then passes onto the 2nd spinningcone, and the movement is repeated several times until the liquidreaches the bottom of the column. As the liquid film is quite thin,the liquid holdup volume is low and the resident time is typicallyaround 20 s. The SCC can handle a range of different materialsas feed, from low-viscosity products (for example, wine) to moreviscous materials such as coffee extract.

A stripping gas, such as nitrogen, is admitted to the base of thecolumn and passes through the voids between the rotating andfixed cones. An alternative stripping vapor can be generated fromredirecting a portion of the product discharge through a heaterprior to reinjection. The gas, along with volatile components ithas picked up, is collected at the top of the column. Along itstortuous path upward, the stripping gas is exposed to considerableturbulence caused by fins attached to the underside of the spinningcones (Figure 9). It is this turbulence and the fact that the liquid isspread out as a thin film on the upper surfaces of the rotating andfixed cones that enhance a mass transfer of volatile product intothe stripping gas. The considerable number of cones also ensuresan adequate path length for both liquid and stripping gas withinthe column.

The column operates under a negative pressure, so volatile com-ponents will be evaporated off at a reduced temperature. Typicalfeed and column temperatures are approximately 30 ◦C. Reason-able clearances between rotating and fixed cones ensure that pres-sure drops are minimized, and this in turn enables the mass transferprocess to occur at almost constant pressure (and hence constanttemperature) within the column (Harders and Sykes 1999). Otherancillary items are required for the process to function efficiently(Figure 10). After leaving the feed tank (1), the product is warmedin a regenerative heat exchanger (3) and fed into the SCC (5).Stripping gas is obtained from treatment of a portion of the prod-uct discharge through a reinjection heater (7), with the remainderof the product discharge recovered once passed back through theheat exchanger (3). On leaving the column, the stripping gas va-pors are fed to a condensate cyclone (8) and volatile componentsare recovered separate to the treated product. The SCC can be

sealed to operate under aseptic conditions and can be a componentof a pasteurizing or sterilizing process. The column and ancillarycomponents can be cleaned using a “clean in place” system.

SCC role in winemaking. The SCC has numerous applica-tions in the wine industry, including recovery of delicate aromas,removal of sulphur dioxide from grape juice, alcohol reduction ofwines, and production of grape juice concentrates. The recoveryof delicate aromas is an important feature of the equipment, asaromas can be lost in certain winemaking operations such as filtra-tion, fining, and oxidation during storage. Flavors can be recoveredfrom juice or from wine before a critical processing operation andthen added back to the wine at the blending stage. Since the SCCcan operate at low temperatures, delicate flavors are able to remain“fresh” and are unlikely to be heat affected.

The SCC has an important role in the removal of alcohol fromwine. The general process for adjusting alcohol concentration infinished wine using SCC technology consists of a 2-stage process.The 1st pass of wine through the SCC occurs at low temperature(approximately 28 ◦C) and vacuum to recover volatile wine aromasin approximately 1% of total product volume. The 2nd pass ofproduct occurs with the dearomatized wine at a slightly highertemperature (approximately 38 ◦C) and vacuum conditions toremove the alcohol. The final dealcoholized wine is constructedby reblending the recovered aroma with the dealcoholized anddearomatized base. Blending with full-strength wine, juice or juiceconcentrates to final product specifications prior to filtration, andpackaging enables a range of product styles to be developed.

An investigation of the effects of the SCC on wine phenoliccomposition arising from the dealcoholization process was under-taken with several Spanish red and white wines. Differences inthe free radical-scavenging activities, resveratrol, total phenolics,flavonols, tartaric esters, flavonoid and nonflavonoids of the base,and dealcoholized wines were attributed to the presence of vary-ing concentrations of sulfur dioxide, which is removed with theethanol, and volumetric changes leading to the concentration ofconstituents in the lowered ethanol wine (Belisario-Sanchez andothers 2009).

The SCC has been used to investigate continuous ethanol re-moval from a fermenting yeast broth (Wright and Pyle 1996). Thebroth was circulated between the SCC and a fermentation vessel,

Figure 9–Cross-section of cone showing fins to create turbulence. 1: stationary cone; 2: rotating cone; 3: fin; 4: rotating shaft. Courtesy Flavourtech,Lenehan Rd.




and ethanol removal efficiency was found to be quite high at 85%.It was observed, however, that the vacuum applied to the SCCaffected the viability of the yeast cells, and the cells became smallerin size and had a different shape. This limitation should not be anissue for finished wines, where fermentation has been completed.

Supercritical solvent extractionCompression of a gas at temperatures above its critical point will

result in formation of a supercritical fluid with increased solvent

properties that can be exploited for separation or liquid extraction.The use of carbon dioxide for supercritical extraction in the foodindustry is gaining popularity and offers several advantages as thecritical temperature for this gas is relatively low at 31 ◦C, no toxicsubstances are required for use, it is relatively inexpensive and easilyhandled (Rizvi and others 1994). Furthermore, the use of carbondioxide in wine production does not pose any legal difficulties andis ideally suited for extraction of alcohol from either wine or beer(Marignetti and others 1992). A patented process for the removalof alcohol from wine or beer using supercritical carbon dioxide ex-

Figure 10–Typical layout of a spinning cone column and ancillary items. 1: product feed tank; 2: product feed pump; 3: product heat exchanger; 4:product discharge pump; 5: spinning cone column; 6: product reinjection pump; 7: product reinjection heater; 8: condensate cyclone; 9: vacuum pump;10: recovered volatile extract pump. Courtesy Flavourtech, Lenehan Rd.

Figure 11–Processing scheme for production of reduced alcohol wines using supercritical carbon dioxide extraction (Seidlitz and others 1991).


R:Co

ncise

Revie

wsin

Food

Scien


traction and the production of low alcohol beverages subjects thehigh alcoholic strength beverage to low-temperature high-vacuumdistillation. The captured volatile fraction containing alcohol andaroma compounds is then subjected to supercritical extraction at80 to 100 bars pressure. Partial expansion of the supercritical fluidby pressure drop to 18 to 25 bars extracts the aroma portion ofthe distillate, which after carbon dioxide scrubbing is returned bysparging into the dearomatized wine base remaining after distil-lation (Seidlitz and others 1991). A flow diagram illustrating theproduction of low alcohol wine via supercritical carbon dioxideextraction is shown in Figure 11. The critical extraction processis conducted in a counter current column in which the solvent(carbon dioxide) is pumped as a liquid into bottom of the columnand the volatile alcohol mixture fed into the top. The extractedvolatile aromas and carbon dioxide gas are recovered from the col-umn head and ethanol–water component drained away as a liquidfrom the bottom.

Pilot-scale experiments for the production of dealcoholizedcider have shown the technical feasibility for producing low al-cohol products using sequential supercritical extraction of aromacompounds, followed by ethanol from the base wine. Reblendingof the aroma and base wine components produced a product withsome similarity to the original cider. However, removal of somearoma compounds and lack of ethanol, presumably to providepalate weight, produced a beverage with considerable differencesfrom the original (Medina and Martınez 1997). While technicallyfeasible, supercritical extraction using carbon dioxide for the pro-duction of low alcohol beverages is not a commonly employedprocess within the beverage industry. High capital costs, a require-ment for high vacuum distillation and the inflexibility of plant,remain significant barriers for the uptake of this technology withinthe wine industry. However, supercritical extractive processes areroutinely used for the manufacture of a range of high-value foods.

Sensory Quality of Low Alcohol WinesVery little published information is available that describes con-

trolled sensory evaluation of reduced alcohol wines, produced bymost of the procedures described in this article, with the excep-tion of wines manufactured from GOX-treated juice. A generalconsumer perception is that reduced alcoholic wines lack bodyand flavor (d’Hauteville 1993). The removal of ethanol will havean obvious effect upon the sweetness and palate weight of a wine,due to the sensory characteristics of alcohol. Increased ethanolconcentrations enhance the perception of bitterness (Fischer andNoble 1994; Nurgel and Pickering 2006), sweetness (Fischer andNoble 1994), body (Nurgel and Pickering 2005; Gawel and others2007), and hotness (Nurgel and Pickering 2006; Gawel and oth-ers 2007). Conversely, lowering ethanol decreases acuity of acidityand astringency (Fischer and Noble 1994). The volatility of aromacompounds is reduced in the presence of ethanol due to theirnonpolar nature and these compounds have increased solubility infull alcoholic strength wines (Voilley and Lubbers 1998). Thus,volatile components may be more easily lost from dealcoholizedwines than full-strength wines during processing. Loss of aromacompounds is likely to be greater in thermal distillation techniquesthan low-temperature processes (Pickering 2000). The removal ofethanol from the wine may also increase the binding of aromacompounds to proteinaceous materials in wines, a process thatleads to diminished volatility, and thus sensory perception of thesecompounds (Voilley and Lubbers 1998). The changes in flavor

profile due to ethanol removal are therefore a complex interac-tion of altered volatility and concentration of aroma compounds,loss of alcohol-related sweetness, and changes to the perception ofmouthfeel characteristics. The magnitude of sensory changes as-sociated with dealcoholized wine is dependent upon the quantityof ethanol remaining in the product.

Future Potential of Ethanol Modified WinesThe anticipated increase in sales of reduced alcoholic beverages

arising from increased consumer awareness of the risks associatedwith alcohol consumption in the early 1990s has not necessarilybeen transcribed from marketing publicity to commercial reality(Howley and Young 1993). A consumer perception that dealco-holized wines are organoleptically inferior products is one of themost significant barriers for sales of these wine styles (d’Hauteville1993). The relative changes in mouthfeel and decreased aromasin reduced alcohol wines may arise from chemical changes involatile compound structure and reduced volatility of esters andhigher alcohols due to the absence of ethanol. The chemicalchange in volatile compounds associated with thermal distilla-tion has led to the development of low-temperature distillationprocesses. However, the capital costs associated with this type ofplant and equipment is relatively high. Recent improvements inmembrane technology, portability, and flexibility of applicationfor treatment of some wine faults ensured that reverse osmosishas become a widely used production process with rapid up-take by wine producers. Technologies, such as an SCC, require asignificant volume of product in order to become economicallyfeasible. Regardless of the technology employed for production ofreduced alcoholic strength wines, a very real issue faced by man-ufactures is aseptic packaging and timely transport of the productto market. Removal of ethanol from the beverage creates a highlysusceptible product for microbial growth and these products mustbe packaged in highly controlled conditions in order to preserveproduct integrity. Blending of ethanol-reduced wines with grapejuice concentrates to enhance varietal composition and improvepalate weight associated with low sugar levels further exacerbatespotential contaminant growth. In spite of these challenges, severalcommercial reduced alcoholic strength products have been mar-keted with success. Although the future for such wine productsremains unclear, the reduction of ethanol concentration in winesto acceptable levels to maintain style consistency between vintagesis, however, likely to remain an important wine production processfor many manufacturers.

AcknowledgmentsThe authors wish to acknowledge the advice of Stephen Guy

from the Australian Wine and Brandy Corporation for assistancein interpretation of Australian Food Standards Code and SteveSykes from Flavourtech Pty. Ltd., Griffith and Trevor Delves forexplanation and provision of information regarding the spinningcone column.

ReferencesAguera E, Bes M, Roy A, Camarasa C, Sablayrolles J-M. 2010. Partial removal of ethanol during

fermentation to obtain reduced-alcohol wines. Am J Enol Vitic 61(1):53–60.Anon. 2005. CPG Sec. 510.400 dealcoholized wine and malt beverages—labeling. Washington,

D.C.: Food and Drug Administration.ANZFA ANZFA. 2002a. Standard 2.7.1 labelling of alcoholic beverages and food containing

alcohol. Canberra: Commonwealth of Australia. 6 p.Anzfa Anzfa. 2002b. Standard 4.5.1 wine production requirements. Canberra: Commonwealth

of Australia. 6 p.




Baldwin G. 1998. Reverse osmosis and its future relevance to the wine industry. Aust NZGrapegrow Winemak 414a:129–32.

Bartowsky EJ, de Barros Lopes M, Langridge P, Henschke PA. 1997. Yeast in the future: therole of genetic engineering. In: Allen M, Leske P, Baldwin G, editors. Advances in juiceclarification and yeast inoculation proceedings ASVO oenology seminar. Adelaide: AustralianSociety of Viticulture and Oenology. p. 26–9.

Belisario-Sanchez YY, Taboada-Rodrıguez A, Marın-Iniesta F, Lopez-Gomez A. 2009. Deal-coholized wines by spinning cone column distillation: phenolic compounds and antioxi-dant activity measured by the 1,1-diphenyl-2-picrylhydrazyl method. J Agric Food Chem57(15):6770–8.

Boidron JN, Chatonnet P, Pons M. 1988. Influence du bois sur certaines substances odorantesdes vin. Connaissance Vigne Vin 22(4):275–94.

Bui K, Dick R, Moulin G, Galzy P. 1986. A reverse osmosis for the production of low ethanolcontent wine. Am J Enol Vitic 37(4):297–300.

Burton M, Rigby D, Young T, James S. 2001. Consumer attitudes to genetically modifiedorganisms in food in the UK. Eur Rev Agric Econ 28(4):479–98.

Cambon B, Monteil V, Remize F, Camarasa C, Dequin S. 2006. Effects of GPD1 overexpressionin Saccharomyces cerevisiae commercial wine yeast strains lacking ALD6 genes. Appl EnvironMicrobiol 72(7):4688–94.

Catarino M, Mendes A, Madeira LM, Ferreira A. 2007. Alcohol removal from beer by reverseosmosis. Sep Sci Technol 42(13):3011–27.

Compagno C, Boschi F, Ranzi BM. 1996. Glycerol production in a triose phosphate isomerasedeficient mutant of Saccharomyces cerevisiae. Biotechnol Progr 12(5):591–5.

Compagno C, Brambilla L, Capitanio D, Boschi F, Ranzi BM, Porro D. 2001. Alterations of theglucose metabolism in a triose phosphate isomerase-negative Saccharomyces cerevisiae mutant.Yeast 18(7):663–70.

Cordier H, Mendes F, Vasconcelos I, Francois JM. 2007. A metabolic and genomic study ofengineered Saccharomyces cerevisiae strains for high glycerol production. Metab Eng 9(4):364–78.

d’Hauteville F. 1993. Consumer Acceptance of low alcohol wines. Int J Wine Market 6(1):35–48.de Barros Lopes M, Rehman A, Gockowiak H, Heinrich AJ, Langridge P, Henschke PA. 2000.

Fermentation properties of a wine yeast over-expressing the Saccharomyces cerevisiae glycerol3-phosphate dehydrogenase gene (GPD2). Aust J Grape Wine Res 6(3):208–15.

Diban N, Athes V, Bes M, Souchon I. 2008. Ethanol and aroma compounds transfer study forpartial dealcoholization of wine using membrane contactor. J Membrane Sci 311(1–2):136–46.

Drewke C, Thielen J, Ciriacy M. 1990. Ethanol formation in adh0 mutants reveals the existenceof a novel acetaldehyde-reducing activity in Saccharomyces cerevisiae. J Bacteriol 172(7):3909–17.

Duerr P, Cuenat P. 1988. Production of dealcoholised wine. In: Smart RE, Thornton RJ,Rodrıguez SB, Young JE, editors. Proceedings of the second international symposium forcool climate viticulture and oenology. Auckland: New Zealand Society for Viticulture andOenology. p. 363–4.

Eglinton JM, Heinrich AJ, Pollnitz AP, Langridge P, Henschke PA, de Barros Lopes M. 2002.Decreasing acetic acid accumulation by a glycerol overproducing strain of Saccharomyces cere-visiae by deleting the ALD6 aldehyde dehydrogenase gene. Yeast 19(4):295–301.

Ehsani M, Fernandez MR, Biosca JA, Julien A, Dequin S. 2009. Engineering of 2,3-butanedioldehydrogenase to reduce acetoin formation by glycerol-overproducing, low-alcohol Saccha-romyces cerevisiae. Appl Environ Microbiol 75(10):3196–205.

Erten H, Campbell I. 2001. The production of low-alcohol wines by aerobic yeasts. J I Brewing107(7):207–15.

Etievant PX. 1991. Wine. In: Maarse H, editor. Volatile compounds in foods and beverages.New York: Marcel Dekker Inc. p. 483–546.

Fischer U, Noble AC. 1994. The effect of ethanol, catechin concentration, and pH on sournessand bitterness of wine. Am J Enol Vitic 45(1):6–10.

Gawel R, Sluyter SV, Waters EJ. 2007. The effects of ethanol and glycerol on the body andother sensory characteristics of Riesling wines. Aust J Grape Wine Res 13(1):38–45.

Geertman J-MA, van Maris AJA, van Dijken JP, Pronk JT. 2006. Physiological and geneticengineering of cytosolic redox metabolism in Saccharomyces cerevisiae for improved glycerolproduction. Metab Eng 8(6):532–42.

Gibson RL. 1986. Cross flow membrane technology for the wine industry. Aust NZ GrapegrowWinemak 268:16–23.

Gonzalez E, Fernandez MR, Larroy C, Sola Ls, Pericas MA, Pares X, Biosca JA. 2000. Charac-terization of a (2R,3R)-2,3-butanediol dehydrogenase as the Saccharomyces cerevisiae YAL060Wgene product. J Biol Chem 275(46):35876–85.

Harders T, Sykes M. 1999. Comparison of a spinning cone column and other distillationcolumns. Food Aust 51(10):469.

Hartmeier W, Willcox IC. 1981. Immobilized glucose oxidase and its use for oxygen removalfrom beer. Tech Q Master Brew Assoc Am 18(3):145–9.

Heard G. 1999. Novel yeasts in winemaking—looking to the future. Food Aust 51(8):347–52.Heldman DR, Hartel RW. 1997. Liquid concentration. In: Heldman DR, Hartel RW, editors.

Principles of food processing. New York: Chapman & Hall. p. 138–76.Heresztyn T. 1987. Conversion of glucose to gluconic acid by glucose oxidase enzyme in Muscat

Gordo juice. Aust NZ Grapegrow Winemak April:25–7.Heux S, Cachon R, Dequin S. 2006a. Cofactor engineering in Saccharomyces cerevisiae: expression

of a H2O-forming NADH oxidase and impact on redox metabolism. Metab Eng 8(4):303–14.Heux S, Sablayrolles J-M, Cachon R, Dequin S. 2006b. Engineering a Saccharomyces cerevisiae

wine yeast that exhibits reduced ethanol production during fermentation under controlledmicrooxygenation conditions. Appl Environ Microbiol 72(9):5822–8.

Hogan PA, Canning RP, Peterson PA, Johnson RA, Michaels AS. 1998. A new option: osmoticdistillation. Chem Eng Prog 94(7):49–61.

Hou J, Lages NF, Oldiges M, Vemuri GN. 2009. Metabolic impact of redox cofactor perturba-tions in Saccharomyces cerevisiae. Metab Eng 11(4–5):253–61.

Howley M, Young N. 1993. Low-alcohol wines: the consumer’s choice? Int J Wine Market4(3):45–56.

Jenson I. 1997. Differences in alcohol production by various yeast strains: myth or fact? In:Allen M, Leske P, Baldwin G, editors. Advances in juice clarification and yeast inocula-tion proceedings ASVO oenology seminar. Adelaide: Australian Society of Viticulture andOenology. p. 24–5.

Karlsson HOE, Tragardh G. 1996. Applications of pervaporation in food processing. TrendsFood Sci Tech 7(3):78–83.

Labanda J, Vichi S, Llorens J, Lopez-Tamames E. 2009. Membrane separation technology for thereduction of alcoholic degree of a white model wine. LWT Food Sci Technol 42(8):1390–5.

Marignetti N, Carnacini A, Antonelli A, Natali N. 1992. Processo per la dealcoholizione delvino e della birra con CO2 allo stato solido. Industrie delle Bevande 21:369–74.

McLeod R, Ough CS. 1970. Some recent studies with glucose oxidase in wine. Am J Enol Vitic21(2):54–60.

Medina I, Martınez JL. 1997. Dealcoholisation of cider by supercritical extraction with carbondioxide. J Chem Tech Biotech 68(1):14–8.

Meier PM. 1992. The reverse osmosis process for wine dealcoholization. Aust NZ GrapegrowWinemak 348:9–10.

Michnick S, Roustan JL, Remize F, Barre P, Dequin S. 1997. Modulation of glycerol andethanol yields during alcoholic fermentation in Saccharomyces cerevisiae strains overexpressed ordisrupted for GPD1 encoding glycerol 3-phosphate dehydrogenase. Yeast 13(9):783–93.

National Health and Medical Research Council (Australia). 2009. Australian guidelines to reducehealth risks from drinking alcohol. Canberra: National Health and Medical Research Council.p. vi, 181 p.

Navarro-Avino JP, Prasad R, Miralles VJ, Benito RM, Serrano R. 1999. A proposal for nomen-clature of aldehyde dehydrogenases in Saccharomyces cerevisiae and characterization of the stress-inducible ALD2 and ALD3 genes. Yeast 15(10A):829–42.

Nevoigt E, Stahl U. 1996. Reduced pyruvate decarboxylase and increased glycerol-3-phosphatedehydrogenase [NAD+] levels enhance glycerol production in Saccharomyces cerevisiae. Yeast12(13):1331–7.

Nurgel C, Pickering G. 2005. Contribution of glycerol, ethanol and sugar to the perception ofviscosity and density elicited by model white wines. J Texture Stud 36(3):303–23.

Nurgel C, Pickering G. 2006. Modelling of sweet, bitter and irritant sensations and theirinteractions elicited by model ice wines. J Sensory Stud 21(5):505–19.

O’Neil MJ. 2006. The Merck index : an encyclopedia of chemicals, drugs, and biologicals. 14thed. Whitehouse Station, N.J.: Merck.

Ough CS. 1975. Further investigations with glucose oxidase-catalase enzyme systems for usewith wine. Am J Enol Vitic 26(1):30–6.

Pickering GJ. 2000. Low- and reduced-alcohol wine: a review. J Wine Res 11(2):129–44.Pickering GJ, Heatherbell DA, Barnes MF. 1998. Optimising glucose conversion in the produc-

tion of reduced alcohol wine using glucose oxidase. Food Res Int 31(10):685–92.Pickering GJ, Heatherbell DA, Barnes MF. 1999a. The production of reduced-alcohol wine

using glucose oxidase-treated juice. Part II. Stability and SO2-binding. Am J Enol Vitic50(3):299–306.

Pickering GJ, Heatherbell DA, Barnes MF. 1999b. The production of reduced-alcohol wineusing glucose oxidase-treated juice. Part III. Sensory. Am J Enol Vitic 50(3):307–16.

Pickering GJ, Heatherbell DA, Barnes MF. 1999c. The production of reduced-alcohol wineusing glucose oxidase treated juice. Part I. Composition. Am J Enol Vitic 50(3):291–8.

Pickering GJ, Heatherbell DA, Barnes MF. 2001. GC-MS analysis of reduced-alcoholMuller-Thurgau wine produced using glucose oxidase-treated juice. Lebensm Wiss Tech-nol 34(2):89–94.

Pilipovik MV, Riverol C. 2005. Assessing dealcoholization systems based on reverse osmosis.J Food Eng 69(4):437–41.

Pretorius IS. 2000. Tailoring wine yeast for the new millennium: novel approaches to the ancientart of winemaking. Yeast 16(8):675–729.

Remize F, Roustan JL, Sablayrolles JM, Barre P, Dequin S. 1999. Glycerol overproductionby engineered Saccharomyces cerevisiae wine yeast strains leads to substantial changes in by-product formation and to a stimulation of fermentation rate in stationary phase. Appl EnvironMicrobiol 65(1):143–49.

Remize F, Andrieu E, Dequin S. 2000. Engineering of the pyruvate dehydrogenase bypassin Saccharomyces cerevisiae: role of the cytosolic Mg2+ and mitochondrial K + acetaldehydedehydrogenases Ald6p and Ald4p in acetate formation during alcoholic fermentation. ApplEnviron Microbiol 66(8):3151–9.

Remize F, Cambon B, Barnavon L, Dequin S. 2003. Glycerol formation during wine fermen-tation is mainly linked to Gpd1p and is only partially controlled by the HOG pathway. Yeast20(15):1243–53.

Ribereau-Gayon P, Dubourdieu D, Doneche B, Lonvaus A. 2006. Handbook of enology:volume 1; the microbiology of wine and vinifications. 2nd ed. New York: John Wiley &Sons.

Rizvi SSH, Yu ZR, Bhaskar AR, Chidambarra Raj CB. 1994. Fundamentals of processingwith supercritical fluids. In: Rizvi SSH, editor. Supercritical fluid processing of food andbiomaterials. London: Blackie Academic & Professional. p.1–26.

Scanes KT, Hohmann S, Prior BA. 1998. Glycerol production by the yeast Saccharomyces cerevisiaeand its relevance to wine: a review. S Afr J Enol Viticul 19(1):17–24.

Seidlitz H, Lack E, Lackner H, inventors. 1991 Jul 23. Process for the reduction of the alcoholcontent of alcoholic beverages. U.S. patent 5034238.

Smith CR, inventor. 1996 Jan 2. Apparatus and method for removing compounds from asolution. U.S. patent 95409.

Smith F. 2002. Engineering wine-techniques used to overcome problems in winemaking. AustNZ Grapegrow Winemak 465:71–4.

Stoll M, Scheidweiler M, Lafontaine M, Schultz H. 2009. Possibilities to reduce the velocity ofberry maturation through various leaf area to fruit ratio modifications in Vitis vinifera Riesling.L. In: Wolpert JA, editor. Proceedings 16th Intl. Giesco Symposium. Davis, Calif.: Group ofinternational Experts of vitivinicultural systems for CoOperation (GiESCO). p. 93–6.

Taherzadeh MJ, Adler L, Liden G. 2002. Strategies for enhancing fermentative production ofglycerol—a review. Enzyme Microb Technol 31(1–2):53–66.

Takacs L, Vatai G, Korany K. 2007. Production of alcohol free wine by pervaporation. J FoodEng 78(1):118–25.

van Oort M, Canal-Llauberes R-M. 2002. Enzymes in wine production. In: Whitehurst R J,Law BA, editors. Enzymes in food technology. Sheffield: Sheffield Academic Press. p.76–90.

Varavuth S, Jiraratananon R, Atchariyawut S. 2009. Experimental study on dealcoholization ofwine by osmotic distillation process. Sep Purif Technol 66(2):313–21.

Villettaz JC. 1987. A new method for the produciton of low alcohol wines and better bal-anced wines. In: Lee T, editor. Proceedings of the sixth Australian wine industry technicalconference. Adelaide: Australian Industrial Publishers. p. 125–8.

Voilley A, Lubbers S. 1998. Flavor-Matrix interactions in wine. In: Waterhouse AL, EbelerSE, editors. Chemistry of wine flavour. Washington, D.C.: American Chemical Society. p.217–29.

Westbrook J. 1989. Technology of reverse osmosis. Process Contr Eng 42:82.


R:Co

ncise

Revie

wsin

Food

Scien


Whiting J. 2010. Regulating winegrape sugar accumulation through leaf removal. Aust NZGrapegrow Winemak 555:18–20.

Wollan D. 2006. The right tools for the job: dealing with cool climate wine styles. In: CreasyGL, Steans GF, editors. Proceedings of the sixth international symposium for cool climateviticulture and oenology. Auckland: New Zealand Society for Viticulture and Oenology. p.159–68.

Wright AJ, Pyle DL. 1996. An investigation into the use of the spinning cone column for in situethanol removal from a yeast broth. Process Biochem 31(7):651–8.

Yu P, Pickering GJ. 2008. Ethanol difference thresholds in wine and the influence of mode ofevaluation and wine style. Am J Enol Vitic 59(2):146–52.


Date post:	30-Nov-2015
Category:	Documents
Upload:	joz-diaz
View:	27 times
Download:	0 times

JFS Vol 77 Is 01 JAN 2012 pp R025-R041 PRODUCTION TECHNOLOGIES FOR REDUCED ALCOHOLIC WINES.pdf

Documents