Natural Product Radiance176

Beverage

Dental erosion and retail sales ofsoft drinks is increasing and this is moreprevalent in lower socio-economic groups.Erosion of tooth tissue by dietary acidsand acidic beverages has been investigatedin detail on enamel in vitro studies.Carbonated soft drinks are potentiallymore erosive than non-carbonatedbeverages due to the additional carbonicacid present.

The scientists at Dental School,N West, UK and Glaxo SmithklineConsumer Healthcare, Coleford,Gloucestershire, UK tested anexperimental formulation of carbonatedblackcurrant drink to determine theerosive potential compared to a

Development of low erosive carbonated fruit drinksconventional carbonated orange drinkand water over a 20 day period using asimilar design as in previous studies. Thestudy was a single centre, single blind,randomised placebo controlled threecell crossover design involving15 volunteers. The test drinks were anexperimental carbonated ready-to-drink(RTD) blackcurrant drink, a conventionalcarbonated RTD orange drink andwater. Two enamel samples were retainedin situ, in the midline of the hardpalate on an upper removable acrylicappliance. Drinks (250 ml volumes) wereconsumed four times per day during20 working days. Measurements ofenamel loss were made on enamel

samples after 2, 5, 10, 15 and 20 days byprofilometry.

The researchers concluded thatthe experimental carbonated blackcurrantdrink caused significantly less enamel lossthan the conventional carbonated orangedrink at all time points measured, but wasnot significantly different from water at2, 5 and 20 days. However, it is possibleto modify carbonated soft drinks in amanner similarly shown with non-carbonated soft drinks, to minimise dentalerosion [West NX, Hughes JA, Parker DM, MoohanM and Addy M, Development of low erosivecarbonated fruit drinks; 2. Evaluation of anexperimental carbonated blackcurrant drinkcompared to a conventional carbonated drink, J Dent, 2003, 31(5), 361-365].

Herbal tea, which is generally apolyherbal formulation made up ofdifferent medicinal plants, is alsoconsidered as a source of antioxidants.The antioxidant activity of food productsor beverages may get affected due toconditions of cultivation, collection,industrial processing, packaging andstorage procedures. Storage conditionsbecome a very important factor as far asantioxidant activity of any herbal tea isconcerned.

The changes in the stability ofantioxidant capacity with time and itsrelation to the phenolic content wereevaluated by researchers at the HerbalResearch, Industrial Toxicology ResearchCentre, Lucknow, India in eight Indianherbal teas. Antioxidant capacity was

determined over a period of 15 monthsfrom the date of their procurement usingassays for SOD mimetic activity, LPOinhibitory capacity and total thiol content,which decreased positively with time.Total phenolic content was determinedspectrometrically according to the Folin-Ciocalteu method and calculated as gallicacid equivalents (GAE). Herbal teas withhigher phenolic content showed acomparatively less decline in antioxidantcapacity. The SOD mimetic activity valuesin control samples (at the time ofprocurement) were seen to be in the rangeof 54.63-93.64 units/min/mg of extractwhich after 15 months of storagedecreased upto 7.4-folds in somesamples. LPO inhibitory capacity wasobserved upto 96.75% in herbal tea E at

the time of procurement which droppedto 63.85% inhibition of MDA formation/5µl of extract after 15 months. In case oftotal thiol, the values were seen in therange of 0.55-1.71 mg/g and after 15months it was from 0.12 to 0.21 mg/g. Inall these cases high antioxidant activity wasseen in the samples with higher phenoliccontent which also showed comparativelyless decline in antioxidant capacity afterconsiderable storage time. The results havesignificance, as most of the herbal teasavailable in the local markets in India donot carry any information regarding theperiod of use without decline in itsbeneficial effects [Naithani Vijay, Nair Smithaand Kakkar Poonam, Decline in antioxidantcapacity of Indian herbal teas during storage andits relation to phenolic content, Food Res Int,2006, 39 (2), 176-181].

Antioxidant capacity of Indian herbal teasduring storage

Vol 5(3) May-June 2006 177

The scientists at LebaneseAmerican University, Byblos, Lebanonworked on effect of acute and chronicgrapefruit, orange and pineapple juiceintake on blood lipid and lipoproteinmetabolism in normolipidemic rats.During experiment the effects of acutejuice intake were studied after three hoursof a single juice-lipid load instilledintragastrically. In the chronic study,blood samples from fasted animals weresubjected to analyses after six months ofeither water [control] or water-juice[ 1 : 1 ]intake. Inthe acutes t u d y ,pineapplea n dgrapefruitsignificantlydecreased

p l a s m atriacylglycerol [TAG], and chylomicron[CM] TAG and cholesterol concentrationsconcomitantly with delayed gastricemptying. Plasma cholesterol levels andvery-low-density lipoprotein [VLDL]secretion and metabolism were notaffected. In the chronic study, onlygrapefruit juice significantly decreasedplasma and VLDL, TAG concentrations andrelative VLDL particle size with respect toother groups. All juices significantlyincreased VLDL apolipoprotein B [apoB]

Beverage

Effect of grapefruit, orange and pineapple juiceintake on blood lipid profile in normolipidemic rats

secretion, but plasma total apoBconcentrations were highest in thegrapefruit group and lowest in the orangeand pineapple groups. No effect on bloodcholesterol levels was observed.

The cardioprotective benefit ofchronic juice intake in normolipidemicrats may be chiefly through mechanismsindependent of a direct effect on bloodlipid profile, although orange andpineapple, but not grapefruit, relativelyimproved the metabolism and clearanceof blood lipoprotein particles. As a resultof delayed gastric emptying, grapefruit andpineapple juices may exhibit moderatesharp increases in postprandial plasmaTAG concentrations accompanying peakdigestion and absorption [Daher CF, Abou-Khalil J and Baroody GM, Effect of acute and chronicgrapefruit, orange and pineapple juice intake onblood lipid profile in normolipidemic rat, MedSci Monit, 2005, 11(12), BR465-BR472].

The behaviour of volatilecompounds according to two enzymatictreatments applied during the manufactureof fruit juices of apricot, peach and pearwas investigated by the team of scientistsat Barcelona, Spain. More than 80compounds were detected of a wide rangeof chemical families (alcohols, aldehydes,ketones, terpenoids, esters,norisoprenoids, ...). Theaspirane and

alpha-isophoron were tentativelyidentified for the first time in apricot andpeach fruits. The enzymes used, forextraction or clarification of fruit juices,modified the polysaccharides separated bymolecular weight and the content ofsoluble polysaccharides. This couldindicate differences in the fruit juicematrix, which could be related to observedchanges in the volatile profile. In apricot,

Assessment of the volatile composition of juicesof apricot, peach and pear

the enzymes enhanced the juice in terpenesand norisoprenoids as varietal compounds.In peach and pear, the enzymes used didnot favour the amount of lactones anddecadienoate esters, the character impactcompounds, respectively [Riu-Aumatell M,Lopez-Tamames E and Buxaderas S, Assessment ofthe volatile composition of juices of apricot, peach,and pear according to two pectolytic treatments,J Agric Food Chem, 2005, 53(20),7837-7843].

Orange juice

Grapefruit juice

Natural Product Radiance178

Beverage

Tea is, next to water, the mostwidely used beverage worldwide. Thebeverage is an infusion of dried leaves ofCamellia sinensis (Linn.) O. Kuntzeand can be classified into the three typesgreen, black and Oolong tea dependingon the process of treatment of the leavesafter harvesting. Green tea is derived fromleaves, which were exposed, to steam ordry heat in order to inactivate oxidativeenzymes. Besides its prominent role as acommon beverage, green tea has gainedmuch interest because of the increasingnumber of reports on beneficial healtheffects.

Recent reports on sporadic casesof liver disorders (acute hepatitis, icterus,hepatocellular necrosis) after ingestion ofdietary supplements based on hydro-alcoholic extracts from green tea leavesled to restrictions of the marketing of suchproducts in certain countries of the EU.Since, green tea is considered to exert anumber of beneficial health effects andtherefore, green tea products are widelyused as dietary supplements, scientistsinvestigated the possible mechanism ofhepatotoxicity of green tea extracts and

Toxicity of green tea extracts and their constituents inrat hepatocytes in primary culture

in the components involved in sucheffects. Thus, a study was designed byresearchers from Germany, France, andSwitzerland to investigate the cytotoxicityof hydro-alcoholic green tea extracts inrat hepatocytes in primary cultures.Furthermore, important constituents ofhydro-alcoholic green tea extracts weretested individually for their cytotoxicity inhepatocytes.

Seven hours after seeding oncollagen, rat hepatocytes in primaryculture were treated with various hydro-alcoholic green tea extracts (two differentnative 80% ethanolic dry extracts and an80% ethanolic dry extract cleared fromlipophilic compounds). Cells werewashed, and reduction of resazurin, usedas a viability parameter monitoring intactmitochondrial function, was determined.It was found that all seven green teaextracts examined enhanced resazurinreduction significantly at a concentrationrange of 100-500 µg/ml medium, whilea significant decrease was observed at 1-3mg/ml medium. Decreased levels wereconcomitant with abundant necrosis asobserved by microscopic inspection of the

cultures and with increased leakage oflactate dehydrogenase activity from thecells. In a separate series of experiments,the green tea constituents (−)-epicatechin,(−)-epigallocatechin-3-gallate, caffeineand theanine were tested atconcentrations reflecting their levels in atypical green tea extract. Synthetic (+)-epigallocatechin (200 µM) was used forcomparison. Cytotoxicity was found with(−)-epigallocatechin-3-gallate only. Theconcomitant addition of 0.25 mMascorbate/0.05 mM α-tocopherol had noinfluence on cytotoxicity. In conclusion,the results suggest that high concentrationsof green tea extract can exert acute toxicityin rat liver cells. (−)-Epigallocatechin-3-gallate seems to be a key constituentresponsible for this effect. The relativelylow bioavailability of catechins reportedafter oral exposure to green tea argues,however, against a causal role of theseconstituents in the reported liver disorders[Schmidt M, Schmitz HJ, Baumgart A, Guédon D,Netsch MI, Kreuter MH, Schmidlin CB andSchrenk D, Toxicity of green tea extracts andtheir constituents in rat hepatocytes in primaryculture, Food Chem Toxicol, 2005, 43(2),307-314].

The scientists at Faculty of FoodScience and Technology, University ofPutra, Malaysia employed a centralcomposite design to optimize theextraction conditions of sapodilla(Achras zapota Linn.) juice using hotwater extraction. The independentvariables were juice extraction time

(30-120min) and temperature(30-90°C). The combined effect of thesevariables on juice yield, odour, taste andastringency were investigated. The resultsshowed that extraction temperature wasthe most important factor affecting thejuice characteristics as it exerted asignificant influence on all the dependent

variables. Higher temperature increasedthe juice yield, taste and odour but alsoshowed an increase in astringency whichaffected the acceptability of the juice [SinHN, Yusof S, Abdul Hamid N Sheikh and RahmanR Abd, Optimization of hot water extraction forsapodilla juice using response surface methodology,J Food Eng, 2006, 74(3), 352-358].

Optimization of hot water extraction for Sapodilla juice

Vol 5(3) May-June 2006 179

There is a lot of scientificevidence indicating that tea consumptionmight have health promoting properties,including the effects of reduction ofcholesterol, depression of hypertension,anti-oxidation and anti-microbial effects,protection against cardiovascular diseaseand cancer. But it has also been suggestedthat certain pollutants in tea leaves maypose a health threat to tea drinkers. Themain pollutants that have been investigatedwidely and intensively are heavy metals,fluoride and pesticides. Relevant sanitarystandards of these pollutants for tea leaveshave been formulated.

PAHs, a class of compounds thatconsist of two or more fused aromaticrings, are a well-known class ofcarcinogens found in some foods and theyhave been intensively studied over the lastfew years. Gaseous and particle-boundPAHs can be transported over long distancesbefore deposition and may accumulate invegetation. This could indirectly causehuman exposure to PAHs through foodconsumption and, thus, might pose ahuman health threat.

Tea leaves possess high surfacearea, so they may accumulate PAHs,especially from air. The productionprocess of tea leaves may also lead PAHsinto product, because many of them aredried using combustion gases fromburning wood, oil or coal. PAHs areinvariably present in the combustion gasesand can be absorbed by tea product whenthey contact. So it is important toinvestigate concentrations and health riskof PAHs in tea, and to formulate sanitarystandards of PAHs for tea. However, littleinformation is available on the release ofPAHs into tea liquor and their health risk;and these are the bases to formulatesanitary standards of PAHs for tea.

The main objectives of the studyconducted by scientists of China were: todetermine PAHs content in 8 brands ofChinese tea; to study the release of PAHsfrom tea by examining theirconcentrations in the tea liquor; and toanalyze the health risk to the teadrinkers by calculating the sanitarystandards of PAHs for tea and the dailyPAHs intake.

Sixteen PAHs weresimultaneously measured in 8 brands oftea and in infusions of one brand of blacktea. It was observed that the total contentsof the 16 PAHs (ΣPAHs) in the tea samplesranged from 323 to 8800 µg/kg with thehighest ΣPAHs found in a black tea. PAHs(3-4 rings) were dominant in all teasamples, with a contribution of77.7-98.7% of the ΣPAHs. Infusion timesfrom 10 to 120 min were studied duringwhich 3.03-7.69% of the total PAHscontained in the black tea was releasedinto the liquor. The percentages of PAHsreleased (RR) from the tea into the liquorwere inversely proportional to the lg K

ow

of the PAHs with a mean formula of RR =261.7/lg K

ow- 41.32 and R = 0.899. To

analyze the potential health risk, sanitarystandards of the 16 PAHs for tea leaveswere calculated to be 0.1-110 mg/kg andthe daily PAHs intake from the black teawas calculated to be 6.36 µg per person[Lin Daohui, Tu Youying and Zhu Lizhong,Concentrations and health risk of polycyclicaromatic hydrocarbons in tea, Food ChemToxicol, 2005, 43 (1), 41-48].

Concentrations and health risk of polycyclicaromatic hydrocarbons (PAH) in tea

Beverage

Calcium in milk is easilyabsorbed by the intestine than the calciumfrom the vegetables and cereals. Hence,high intake of calcium is possible throughformulating calcium fortified dairyproducts. The scientists at National DairyResearch Institute, Karnal, Haryana, Indiafortified milk with calcium at the rate of50 mg/100 ml using three salts of calcium,viz. calcium chloride, calcium lactate and

calcium gluconate. Fortification of milkwith these salts destabilized the milkdrastically due to decrease in its pH.However, the calcium fortified milk wasstabilized by adjusting its pH withdisodium phosphate which restored itsheat stability. Fortification of milk withcalcium and adjustment of pH with basecaused a significant increase in viscositybut a significant decrease in the curd

tension. Higher calcium in the aqueousphase might lead to higher absorption ofthe added salts. The fortified milk can beused by individuals who may not ingestenough calcium to meet minimum dailyrequirements [Arora S, Ranjan P, Sharma GS,Sindhu JS, Singh G, Singh AK and Kansal VK, Effectof calcium fortification on heat stability andphysico-chemical properties of mixed (Cow andBuffalo 1:1) milk, Indian J Dairy Sci, 2005,58(4), 242-246].

Effect of calcium fortification on mixed milk

Natural Product Radiance180

Green tea is produced from theleaves of the evergreen plant Camelliasinensis (Linn.) O. Kuntze. It containsvarious useful chemical compounds suchas catechins, caffeine and vitamins, mostnotable components being catechinsincluding EGCG, ECG, EGC and EC.

These compounds from green teawere evaluated by researchers at theDepartment of Biotechnology, College ofEngineering, Yonsei University, Seoul,South Korea for their ability to inhibitinfluenza virus replication in cell cultureand for potentially direct virucidal effect.Among the test compounds, the EGCG andECG were found to be potent inhibitorsof influenza virus replication in MDCK cellculture and this effect was observed in allinfluenza virus subtypes tested, includingA/H1N1, A/H3N2 and B virus. The 50%

effective inhibition concentration (EC50

)of EGCG, ECG and EGC for influenza A viruswere 22-28, 22-40 and 309-318 µM,respectively. EGCG and ECG exhibitedhemagglutination (HA) inhibition activity,EGCG being more effective. However, thesensitivity in hemagglutination inhibitionwas widely different among three differentsubtypes of influenza viruses tested.Quantitative RT-PCR analysis revealed that,at high concentration, EGCG and ECG alsosuppressed viral RNA synthesis in MDCK

cells whereas EGC failed to show similareffect. Similarly, EGCG and ECG inhibitedthe neuraminidase activity more effectivelythan the EGC. The results show that the 3-galloyl group of catechin skeleton playsan important role on the observedantiviral activity, whereas the 5′-OH at thetrihydroxy benzyl moiety at 2-positionplays a minor role. The results, along withthe HA type-specific effect, suggest thatthe antiviral effect of catechins on influenzavirus is mediated not only by specificinteraction with HA, but altering thephysical properties of viral membrane[Song Jae-Min, Lee Kwang-Hee and Seong Baik-Lin, Antiviral effect of catechins in green tea oninfluenza virus, Antiviral Res, 2005, 68(2),66-74].

Antiviral effect of catechins in green tea oninfluenza virus

The team of scientists at GraduateInstitute of Nutrition and Health Sciences,Taipei Medical University, Taipei, Taiwan,China investigated the effects of fermentedsoy milk powder on the antioxidative statusand lipid metabolism in the livers of CCl

4-

injected rats. During experiment forty-fivehealthy male Sprague-Dawley rats wererandomly assigned to five groupsaccording to five different diets: control(AIN-76), AIN-76+high-dose fermentedsoy milk powder, AIN-76+low-dosefermented soy milk powder, AIN-76+high-

dose milk yogurt powder and AIN-76+low-dose milk yogurt powder. The experimentlasted for 8 weeks. After 4 weeks, all therats received intraperitonealadministration of CCl

4(0.2 ml/100g body

wt) every week. Total cholesterol (TC),triglyceride (TG), thiobarbituric acidreacting substances (TBARS), alkalinephosphatase (ALP) and antioxidativeenzymes in the liver were evaluated.Results showed that there was also nosignificant difference in TBARS andantioxidative enzymes in the liver. TC and

Effects of fermented soy milk onthe liver lipids under oxidative stress

TG in the groups fed with fermented soymilk powder were generally lower thanthose fed with casein powder. It isconcluded that consumption of fermentedsoy milk helps in lowering totalcholesterol and TG accumulation in theliver under CCl

4-induced oxidative stress

[Lin CY, Tsai ZY, Cheng IC and Lin SH, Effects offermented soy milk on the liver lipids underoxidative stress, World J Gastro, 2005, 11(46),7355-7358].

Beverage

Vol 5(3) May-June 2006 181

CYANMAGENTAYELLOWBLACK

Carotenoids represent importantbiological compounds that are widelydistributed in fruits and vegetables. Of thevarious carotenoids, lycopene has receivedconsiderable attention in recent yearsbecause of its possible role in theprevention of chronic diseases such asprostate cancer. Epidemiological studieshave also shown that the increasedconsumption of lycopene-rich foods, suchas tomatoes and tomato-based products,is associated with a low risk of cancer. Inaddition to lycopene, both lutein and β-carotene are also present in tomatoes inmuch smaller amounts.

Scientists at Department ofNutrition and Food Science, Fu JenUniversity, Taipei, Taiwan studied thestability of carotenoids in tomato(Lycopersicon esculentum Mill.)juice during storage. Tomato juice was

processed by hot-breaking of tomatoes at82°C, screening, heatingat 121°C for 40 secondsand then storing in thedark or under light at 4,25 and 35°C for 12

weeks. Results showed that the amountsof all-trans-lutein and its cis isomersdecreased with increasing storage time forall the treatments. Light enhanced thedegradation and isomerization of all-trans-lutein, and 13-cis-lutein was moresusceptible to formation than 9-cis-lutein.Similar trends were observed forβ-carotene and lycopene. However, lightexposure promoted the formation ofdi-cis-, 9-cis- and 13-cis-β -carotene. Forlycopene, 15-cis-lycopene was the majorisomer formed during dark storage at 4°C,while 9-cis- and 13-cis-lycopene were

Stability of carotenoids in tomato juice during storagefavoured at 25°C and 5-cis- as well as13-cis-lycopene dominated at 35°C. Underlight storage, both 9-cis- and di-cis-lycopene (II) were the main isomersgenerated at 35°C, whereas 13-cis- and15-cis-lycopene were the most abundantat 4 and 25°C.

In conclusion, the higher thestorage temperature, the greater are thelosses of all-trans plus cis forms of lutein,β-carotene and lycopene duringillumination. All-trans-lycopene showedthe highest degradation loss, followed byall-trans-β-carotene and all-trans-lutein.More cis-isomers of lycopene than luteinor β-carotene were generated duringstorage. However, the type of majorisomers formed may be inconsistent,depending on storage conditions [Lin CHand Chen BH, Stability of carotenoids in tomatojuice during storage, Food Chem, 2005, 90 (4),837-846].

Beverage

The increasing quality demand forfresh fruits results in an increase in rejectedmelons (Cucumis melo Linn.). Juiceprocessing could overcome the productlosses occurring but thermal sensitivity ofmelon juice flavour prohibits conventionalthermal processing. Scientists of France andCosta Rica use membrane processes formicrobial stabilization and concentrationand developed a novel way of using permeate(clear juice) as well as retentate (pulpyjuice). Enzyme activities in the productsduring and after processing may need someattention prior to industrial application of theprocess.

Melon juice obtained from fruits

discarded by exporters was first clarified bycrossflow microfiltration and thenconcentrated by osmotic evaporation (OE).The resulting clarified melon juice was highlysimilar to the initial juice, except for insolublesolids and carotenoids, which wereconcentrated in the retentate. Averagepermeation flux was relatively high (about80 litre/hr/m2), with continuous extractionof retentate at a volumetric reduction ratio of3. After concentration of the clarified melonjuice to as much as 550g/kg of total solublesolids using a continuous feed-and-bleedprocedure of OE, it is found that almost theentire composition of the product waspreserved. This integrated membrane

process is a genuinely innovative way oftreating melon juice, as it allows high-valueproducts to be obtained from fruitsdiscarded by the fresh market. On one hand,the clarified melon juice and its concentratecan be marketed as part of fruit beverages towhich they can contribute fruit sugars andspecific aroma; on the other hand, a pulpyjuice (retentate), which is enriched inprovitamin A and can be used as raw materialto extract β-carotene or directly in functionaldrinks, is obtained [Vaillant Fabrice, Cisse Mady,Chaverri Marco, Perez Ana, Dornier Manuel, ViquezFloribeth and Dhuique-Mayer Claudie, Clarificationand concentration of melon juice using membraneprocesses, Innov Food Sci Emerg Technol,2005, 6(2), 213-220].

Clarification and concentration ofmelon juice using membrane processes

Natural Product Radiance182

Beverage

Nutritional beverages areformulated to provide specific nutrientcombinations to individuals with specialdietary needs. Many nutritional beveragesare consumed as oil-in-water emulsionsthat consist of small lipid dropletsdispersed in an aqueous liquid. Theadvantage of using oil-in-water emulsionsis that a combination of oil-soluble,water-soluble and amphiphilic nutrientscan be combined into a single productthat is convenient to manufacture, storeand consume. A recent survey ofcommercial emulsion-based nutritionalbeverages has found that they have fatcontents between 1 and 7 wt%, proteincontents between 1 and 5 wt%, and pHvalues between 6.5 and 7.0. In addition,these products usually contain relativelyhigh concentrations (>1 mM) of certain typesof mineral ions, e.g., Na, K, Ca, P, Cl and Mg.

emulsions prior to heating decreased, butdid not prevent, droplet aggregation in theemulsions. EDTA was more effective thancitrate in decreasing droplet aggregation.Heat treatment increased the amount ofchelating agents required to preventdroplet aggregation in the emulsions.Free-calcium concentration and dropletsurface potential was independent of heat-treatment temperature, indicating that theperformance of the chelating agents inbinding calcium ions was not affected bythe heat treatment. It was suggested thatincreased hydrophobic attractiveinteractions between the dropletsoccurred during heating, which induceddroplet aggregation [Keowmaneechai E andMcClements DJ, Influence of EDTA and citrate onthermal stability of whey protein stabilized oil-in-water emulsions containing calcium chloride,

Food Res Int, 2006, 39 (2), 230-239].

Influence of EDTA and citrate on thermal stabilityof whey protein stabilized oil-in-water emulsions

containing calcium chlorideThe influence of calcium ions and

chelating agents on the thermal stabilityof model nutritional beverages wasexamined by Scientists of Thailand andUSA. Oil-in-water emulsions [6.94% (w/v) soybean oil, 0.35% (w/v) WPI, 0.02%(w/v) sodium azide, 20 mM Tris buffer,0–10 mM CaCl

2, and 0–40 mM EDTA or

citrate, pH 7.0] were stored attemperatures between 30 and 120°C for15 minutes. The particle size, particlecharge, creaming stability, rheology andfree-calcium concentration of theemulsions were then measured. In theabsence of chelating agents, appreciabledroplet aggregation occurred in emulsionsheld at temperatures from 80 to 120°C,which led to increased emulsion particlediameter, shear-thinning behaviour,apparent viscosity and creaming instability.Addition of chelating agents to the

Potato fruit juice, i.e. the streamresulting after the extraction of the starchfrom the potato, contains up to 2.5% [w/w] of proteins that are potentially valuablefor the food market. However, today therecovery of protein from the potato fruitjuice with reverse osmosis membranesresults in a protein concentrate that is notsuitable for human consumption. The

investigations conducted by scientists ofThe Netherlands, Germany and Denmarkshowed that the use of ultrafiltration withadditional diafiltration is able to producea higher quality protein. Tests with theproduced protein show that the qualitydepends on the rate of diafiltration usedand that the product has functionalproperties that are equal or better than

the compared commercial food productthat are currently used [Zwijnenberg HarmenJ, Kemperman Antoine JB, Boerrigter Marcel E, LotzMartin, Dijksterhuis Jan F, Poulsen Poul Emil andKoops Geert-Henk, Native protein recovery frompotato fruit juice by ultrafiltration, Desalination,2002, 144(1-3), 331-334].

Native protein recovery frompotato fruit juice by ultrafiltration

Vol 5(3) May-June 2006 183

Beverage

It has been reported thatincorporation of a proportion of carrot juiceprovides a considerable contribution to thenutritive characteristics of orange juicebecause oranges have high vitamin C content,and the carrot have highest level of carotene.

Thermal processing is one of themethods by which appropriate foods arepreserved and made available to theconsumer. During thermal treatment, inaddition to the inactivation ofmicroorganisms, varying percentages ofdesirable constituents such as nutrients,colour, flavour and texture are destroyed.Retention studies of vitamins to assess theeffects of food processing on the nutritivevalue of foods are of great importance tofood technologists and consumers.Vitamin C is thermolabile itsconcentration decreases during storage,depending on storage conditions, such astemperature, oxygen content and light.Pulsed electric field electro-technology

(PEF) has the potential to pasteurizeseveral foods nonthermally via exposureto high-voltage short pulses while thematerial is between the electrodes of atreatment chamber.

The scientists at Spain worked onthe shelf life of orange-carrot juice treatedby PEF. They studied the degradationkinetics of ascorbic acid in the juice(stored at 2 and 10°C) according to thePEF conditions applied. In parallel theyapplied a conventional thermal treatmentto orange-carrot juice and compared theresults. For experiment the mixed orangeand carrot juice was obtained afterappropriate washing and hygienization ofthe oranges, the juice was extracted andplaced in a tank. Carrot juice was obtainedafter washing the vegetables first with adiluted solution of sodium hydroxide andafterwards with drinking water. Thewashed vegetables were ground, and thejuice was sifted and mixed with the orange

High pulsed electric field technology is better thanpasteurization for ascorbic acid stability of refrigerated

orangeñcarrot juicejuice (80% orange and 20% carrot). Themixed juice was packaged in Elopackpackages and frozen (− 40°C).

The results revealed that PEFprocessing is an alternative to conventionalthermal pasteurization of orange-carrotjuice. Ascorbic acid is a good parameterfor this. PEF treatment at 25 kV/cm for280-330 µs allows the half-life of the juiceto reach 50 days when stored at 2°C,whereas when the preservationtemperature is 10°C the half-life is 19 days.The ascorbic acid content in juice treatedby PEF is greater than in juice pasteurizedconventionally, and it is maintained for alonger period when stored in refrigeration,so that its nutritive value is also greater[Torregrosa F, Esteve MJ, Frígola A and Cortés C,Ascorbic acid stability during refrigerated storageof orange-carrot juice treated by high pulsed electricfield and comparison with pasteurized juice,J Food Eng, 2006, 73(4), 339-345].

The scientists at Higher Schoolof Food Industries of Tunis, Tunisiainvestigated a new method that may beused to globally quantify the qualitydegradation of a food product duringstorage or commercialization. The newconcept is based on defining andformulating a single index called theGlobal Stability Index (GSI), varyingbetween zero and one and takingsimultaneously into account the time

variations of all pertinent quality indicesproper to the food product under study.This index enables one to judge thedegradation of the microbiological, thephysicochemical and the sensory qualityof the food product during storage in aglobal fashion. The new method, referredto as the GSI method, has been successfullytested in studying the stability of an orangebased carbonated beverage bysimultaneously considering the time

variations of the brix and the CO2 partial

pressure of the drink. It is particularlyrecommended that the proposed index isto be used in comparing the qualitydegradation rates of a given food productstored under different conditions or thoseof different products stored under acommon set of conditions [Achour Mohsen,A new method to assess the quality degradation offood products during storage, J Food Eng, 2006,75(4), 560-564].

New method to assess the quality degradation of foodproducts and beverages during storage