Food Flavor

Chapter 11 in your textbook

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OH

OH

OH

O

OH

OH

OOH

O

OH

OH

Intermolecular Copigmentation

+

OH

OH

OH

OH

O

OH

OH

OOH

O

OH

O

OCyanidin-3-ß-D-glucoside Cyanidin-3-(6-O-p-coumaroyl-

ß-D-glucoside

Copigment “Stacking”

=

Hyperchromic shiftBathochromic shift

Pigment

Co-Factor

Co-Factor

Anthocyanin Color

The poor stability of anthocyanins creates the need to modify stability or find new sources Increase color and oxidative stability

Result: More red color at higher pH levels Greater application range in foods Enhanced antioxidant capacity; health benefits

AbsAbs

nmnm

Flavor Chemistry

Flavor is a combination of taste and aroma

Taste - sweet, sour, bitter, salty- only what can be sensed on the tongue- nerve sensations for metallic and astringent

Aroma - volatiles are released in mouth and then sensed in the nasal cavity

Sensory Impressions Visual impression

Color, size, shape, luster

Odor Volatile, odor-active compounds

Taste Sweet, sour, bitter, salty

Somato-sensory Pain, burning, cold, warmth, astringent, fizzy

Trigeminal nerve response

Texture, resistance, elasticity Sounds

Modern “Flavor” Chemistry Savory

Roast, Pan Dripping, Seared , Grilled , Braised, Au jus Diary

Milk, cream, dairy, cheese, butter, sweet brown flavors, and dairly masking agents

Fruit Natural, synthetic, WONF, enhancers, mimics, green,

citrus, floral, tropical, exotic, complimentary Beverages

Nutritionally enhanced/fortified, soy milks, tea, coffee, liqueurs, energy, fortified waters, dry drink bases, syrups

Sweet

Molecular Basis of Sweetness

-OH groups Acree and Shallenberger AH/B concept

Acree and Shallenberger… “…(Shallenberger & Acree) published a paper entitled the

"Molecular Theory of Sweet Taste" in Nature [1969]. The model developed in that paper for sweetness was based on

a structure-activity relationship between the simplest sweet tasting compounds and their structural features of the stimulants and has become known as the AH-B theory.

The theory described with considerable success the structural features necessary for sweetness but it was not sufficient to predict sweetness.

That is, not all compounds that satisfied the theory tasted sweet nor was the theory able to predict potency level especially for the very high potency sweetners subsequently synthesized.

However, all sweet compounds seemed to have an identifiable AH-B feature.

AH/B Model

AH – Weak acid, B - electronegative group

The perception of sweetnessis proposed to be due to achemical interaction that takes place on the tongueBetween a tastant moleculetastant moleculeand tongue receptor proteintongue receptor protein

THE AH/B THEORY OF SWEETNESSA sweet tastant molecule (i.e. glucose) is called the AH+/B- “glycophoreglycophore”.

It binds to the receptor B-/AH+ site through mechanisms that include H-bondingH-bonding. Intermolecular, anti-parallel hydrogen-bonding interaction

AH

B

B

AH

Glycophore

γ

γ

Tongue receptor protein molecule

Hydrophobic interaction

For sweetness to be perceived, a molecule needs to have certain requirements. It must be solublesoluble in the chemical environment of the receptor site on the tongue. It must also have a certain molecular shapeshape that will allow it to bond to the receptor protein.

Lastly, the sugar must have the proper electronic distribution. This electronic distribution is often referred to as the AH, B system. The present theory of sweetness is AH-B-X (or gamma). There are three basic components to a sweetener, and the three sites are often represented as a triangle.

AH+ / B-

Gamma (γ) sites are relatively hydrophobichydrophobic functional groups such as benzene rings, multiple CH2 groups, and CH3

Identifying the AH+ and B- regions of two sweet tastantmolecules: glucose and saccharin.

Saccharin Sweet’n Low, The 1st artificial sweetener Accidentally found in 1879 by Remsen and Fahlberg Saccharin use increased during wars due to sugar

rationing By 1917, common table-top sweetener in America Banned in 1977 due to safety issue 1991, withdrew ban, but with warning label 2000, removed warning label Intensely sweet, but slight bitter aftertaste

Aspartame Nutrasweet, Equal Discovered in 1965 by J. Schlatter Composed of aspartic acid and phenylalanine 4 kcal/g, but 200 times sweeter Approved in 1981 for table-top sweetener and

powdered mixes Safety debating 1996, approved for use in all foods and beverage Short shelf life, not stable at high temperature

Sucralose Splenda 1998, approved for table-top sweetener and use

in various foods Approved already in UK, Canada before US Only one “made from sugar”

There was a law suit last year of this claim Splenda lost….not a natural compound….a bit of a

deceptive marketing.

Clean, sweet taste and no undesirable off-flavor

Acesulfame K Sunette, Sweet One Discovered in 1967 by Hoechst 1992, approved for gum and dry foods 1998, approved for liquid use Blending with Aspartame due to synergistic effect Stable at high temperature and long shelf life (3-4

years) Bitter aftertaste

Neotame Brand new approved sweetener (Jan. 2000) 7,000 ~ 13,000 times sweeter than sugar Dipeptide methyl ester derivative; structurally

similar to Aspartame Enhance sweetness and flavor Baked goods, non-alcoholic beverages

(including soft drinks), chewing gum, confections and frostings, frozen desserts, processed fruits and fruit juices, toppings and syrups.

Safe for human consumption

Reb-A (diterpene glucoside)

http://www.reb-a.com/

Food flavors Mixtures of natural and/or artificial aromatic compounds designed to impart a flavor, modify a flavor, or mask an undesirable flavor

Natural versus ArtificialNatural - concentrated flavoring constituents derived from plant or animal sources

Artificial - substances used to impart flavor that are not derived from plant or animal sources

Most natural flavors are concentrated from botanicals -plants, trees, fruits, and vegetables

Most artificial flavors are synthesized with high purity- pharmaceutical flavors

Isolation techniques- Steam distillation - mint and herbal oils- Solvent extraction - vanilla & oleoresins- Expression - citrus oils- Supercritical fluid extraction – targeted extractions

Flavor Houses

Givaudan

IFF

Bell Flavors

Wild

Sensus Flavors

Virginia Dare

Blue Pacific

Natural flavors can also be enzymatically or chemically produced

- Fermentation reactions- Microbial enzymes

Saccharomyces Sp.Lactobacillus Sp. BacillusSp. Molds

Maillard flavor compounds

Glucose + Glutamic acid = chickenGlucose + Lysine = burnt or fried potatoGlucose + Methionine = cabbageGlucose + Phenylalanine = caramel

Fructose + Glutamic acid = chicken Fructose + Lysine = fried potato Fructose + Methionine = bean soup Fructose + Phenylalanine = wet dog

Artificial Flavors

Typically are esters

Esters have pleasant fruity aromas, derived from acids

a condensation reaction

ACID + ALCOHOL --> ESTER + WATER

Most artificial flavors are simple mixtures of esters

i.e.Isobutyl formate + isobutyl acetate = raspberry

FERMENTATION and FLAVOR

O O

Diacetyl (CH3 – C - C – CH3 ) is a compound produced by Yeasts via fermentation of carbohydrates

Major compound in the flavor of cultured dairy products Butter and butter-like flavor

Compounds potentially used for diacetyl formation

Lactic acid Oxalacetic acid

Pyruvic acid acetyl lactic acid

Acetaldehyde Citric acid

Flavor stabalization

- Need to protect from light, heat, oxygen, water

- Liquid flavors are typically dissolved in solvents

Partially hydrogenated oil or brominated vegetable oil

Ethanol, propylene glycol, glycerin

Dry flavors are typically encapsulated

- Spray drying- Use of excipients

Plating - coat flavor onto sugar or salt

Extrusion - glassy sugar film

Inclusion complex - beta cyclodextrins

Secondary coatings - high melting temperature fat

Flavor interactions

pH, tartness of acids dependent on acid

Acidulant, the type of acid used influences intensity of other flavors

Carbohydrates, can bind flavor compounds, so less flavor may be needed at low sugar levels

Sweeteners, sweetness can impact flavor intensity

Lipids, flavors partition, fat helps flavor impact

Protein, selective binding of flavor compounds

Flavors complex mixtures of many compounds

-Amyl, butyl, ethyl esters- Amyl acetate = sweet fruity/ banana/ pear- Amyl caproate = sharp fruity/ pineapple- Amyl formate = sweet/ fruity

-Organic acids containing aldehydes , aromatic esters, alcohols, ketones

- Acetic acid = vinegary - Propionic acid = sour milk - Butyric acid = buttery

- Green flavors- cis 3-hexenol = green leafy- trans 2-hexenal = green apple

- Citrus flavors are mixtures of:- Aldehydes- Aromatic esters- Terpenes- Alcohols

- Terpenes - Limonene = sweet citrus/ orange peel- Alpha pinene = warm resinous/ pine-like- Dipentene = fresh citrus/ lemon like

- Floral aldehydes- Citral = floral/ sweet/ lemon (Pledge)- Octanol = floral/ fatty/ orange-like

- Dairy flavors - chemical and enzymatic -Short chain fatty acids Aliphatic alcohols

- propyl, butyl, octyl-Lactonones

- large chain delta lactones-Aliphatic aldehydes

-acetyldehyde, butyraldehyde

- Sulfides - dimethyl, butyl, dimethyl sulfides-Aliphatic esters

- butyrates, laurates, valerates- Di-keytones

- diacetyl, acetylpropionyl- Lactones

- undecalactone (C11) = peach/ sweet- octalactone (C8) = cooked coconut/ sweet

Gamma-Octalactone

http://www.iff.com/Ingredients.nsf/FragIngredients!OpenForm

Brown flavors

- Caramelized, roasted or burnt character- Bread-yeast, caramel, chocolate, coffee, maple, peanut

- Sweet brown compoundsVanillin = sweet/ chocolate-likeMaltol = sweet/ malty/ brown (flavor enhancer)Di-hydrocoumarin = sweet/ caramel/ nutlike

- Non-sweet brown compounds- Dimethyl pyrazine = nutty/roasted- 2,3,5 trimethyl pyrazine = chocolate/ roasted

Flavor Compounds Formation by Maillard Reaction

Reducing Sugars and -amino acids

N-glycosylamine or N-fructosylamine

1-Amino-1-deoxy-2-ketose (Amadori intermediate) or 2-Amino-2-deoxy-1-aldose (Heynes intermediate)

Reductones and Dehydroreductones

Furans ThiophenesPyrroles

Retroaldol ReactionH2S

NH3

Strecker degradation

Amino Acids

Hydroxyacetone HydroxyacetylaldehydeAcetoinAcetylaldehyde

Glyoxal Pyruvaldehyde Glycerolaldehyde

Strecker Aldehydes +

CO2 + -aminoketone

(Methional, NH3, H2S)

HeterocyclizaionPyrazinesPyridinesOxazoles

ThiazolesPyrroles

++

- Woody compounds- Alpha lonone = woody/balsamic/violet/red raspberry-Beta lonone = woody/balsamic/black raspberry

- Spicy compoundsCinnamic aldehyde = cinnamon

Eugenol = clovesThymol = thymeZingerone = ginger oilCapsicum = peppers

- Sulfur compounds- Diallyl disulfide = garlic onion- Methyl mercaptan = natural gas- Methyl thio butyrate = sour milk

Sour

SOURNESS and sour taste is often thought of as “acid”

However there is not a simple relationship between acid concentration (pH) and sourness

Organic acids differ in sourness:

CITRIC ACID (0.05 N solution): “fresh taste sensation”

LACTIC ACID (0.05 N solution): “sour, tart”

PROPIONIC ACID (0.05 N solution): “sour, cheesy”

ACETIC ACID (0.05 N solution): “vinegar”

PHOSPHORIC ACID (0.05 N solution): “intense”

MALIC ACID (0.05 N solution): “green”

TARTARIC ACID (0.05 N solution): “hard”

Bitter

BITTERNESS cqn be attributed to several inorganics and organics

KI CsCl MgSO4Certain amino acids and peptides (dipeptide leucine-leucine)

Alkaloids derived from pyridine (N-containing 6-membered ring)and purines

A = caffeine (1, 3, 7 trimethylxanthine) B = theobromine (from cacao)

GYCOSIDES are sugars that have been added to a natural compound.

Grapefruits generally have a bitter taste to them.

This is due to the flavonoid compound Naringin.

Naringin actually has 2 sugars (both glucose) as part of its structure.

Compound is still intensely bitter.

Removal of these sugars with naringinase, will render the compound tasteless.

Naringin is then converted to Naringinin.

The “de-bittering” of grapefruit juice can be done, if desired.

Where rutinoside is the sugar:

Salty

“SALTY” depends on the nature of the cation and anionin the ionic salt crystal structure; high molecular weight salts may be “bitter”; some salts may even exhibit “sweetness”

Examples:

NaCl NaBr NaI KCl LiBr NaNO3 = salty

KBr = salty + bitter

Lead acetate (toxic) = sweet

Trigeminal Response

“HOTNESS” (pungency) is characteristic of piperine in black pepper and capsicum in red pepper and gingerols in ginger

“Cool” is a characteristic of mentholPeppermint or mint oils

OH

OMe

OH

eugenol menthol

“Spicy” is a characteristic of eugenolClove, nutmeg, cinnamon, bay leaf

Aromas

Sources of Aromas in FoodNatural flavors

Herbs and spices (some enzymatic rxns) Fruits (biosynthesis during ripening)

Process flavors Browning and Maillard Lipid oxidation Fermentation

Artificial flavors Single compounds with character impact

Isoamyl acetate = bananna

Allium sp.(onions, garlic, shallots, leeks)

S-(1-propenyl)-L-cysteine sulfoxide

Allinase

1-propenyl sulfenic acid

Thiopropanal S-oxide

(Tear maker)

Chemical

rearrangement

Mercaptans (thios)Disulfides

Chemical

Rearrangement w/heat

Lipoxygenase Generated Flavors

COOH

O2

COHCOH

A B

lipoxygenase

hexenal nonadienal

“green” “melon, cucumber”

Vanilla- an extracted flavor

VanillinSeed pods of Planifolia

(a tropical orchid)

Sunlight Flavor

Sunlight will induce oxidized flavor and sunlight flavor and hay-like flavor.

Oxidized flavor Sunlight flavor: burnt and / or cabbage

Riboflavin (B2) Effect on Sunlight FlavorRiboflavin is a catalyst for production of the sunlight flavor.

1) Milk protein and riboflavin sunlight sunlight flavor

2) Riboflavin increase in milk will increase the sunlight flavor

3) Riboflavin removal prevent the sunlight flavor

According to the TG Lee Website: Studies at the Silliker Laboratories in Illinois, the

University of Michigan, and other leading labs and universities concluded that both sunlight and the fluorescent lighting in stores could decrease the freshness and flavor of milk and the potency of vital vitamins in it. But this research also showed that the majority of natural and artificial light could be blocked by containers that were yellow instead of white.

Riboflavin Effect on Sunlight Flavor

Riboflavin is a catalyst for production of the sunlight flavor.

1) Milk protein and riboflavin sunlight sunlight flavor

2) Riboflavin increase in milk will increase the sunlight flavor

3) Riboflavin removal prevent the sunlight flavor