Types of FlavorsThermally Induced FlavorsStability in Food SystemsEffects of processing and Storage

ContentsIntroductionTypes of FlavorsThermally Induced FlaovrsStability in Food SystemsEffects of processing and Strage

Flavor PerceptionChemistry

IntroductionThe perfume of a rose, the tang of an ocean breeze, the

aroma of a sizzling steak—tastes and smells, two of our senses by which we characterize the world around us. And yet, we can not adequately express, define, or explain our taste and smell sensations. We can record the sounds we hear, we can photograph the sights we see, but we cannot store and retrieve the flavor of a food or the scent of a flower except in and from our mind.”

— Irwin Hornstein and Roy Teranishi, USDA

ImportanceFlavor is one of the most important components responsible

for the overall sensory properties of taste and smell in any food products (e.g., soft drinks). Among the many organoleptic quality components, such as color, rheological properties or packaging, flavor takes a particular place through stimulating the odor and taste receptors when eating. Therefore, flavor plays an important role in consumer satisfaction, which will subsequently drive consumers’ acceptance and influences the continued consumption of foods. However, due to the volatility and delicate properties of volatile flavor compounds, they are unstable (Tan et al, 2014)

Flavor PerceptionGustatory, olfactory, and oral–somatosensory cues all

contribute directly to flavor perception

ISO 5492 1992:- Flavor as a “complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting.”

ISO 5492 2008 :- The flavor may be influenced by tactile, thermal, painful and/or kinesthetic effects

Multisensory perceptionAlthough, flavour is initially influenced by the receptors

in the eyes, nose, tongue and mouth lining, it is the brain which interprets the overall sensation occurring in the mouth (Taylor and Hort, 2004).

SmellAroma can be sensed orthonasally (i.e. sniffed through

the nostrils), or aroma compounds can reach the olfactory receptors via the throat after the mastication process, retronasally (Taylor and Hort, 2004).

TasteThe taste sensations of sweetness, sourness, bitterness,

saltiness and umami are detected by taste buds located in the oral cavity. These taste buds are found on the surface of the tongue in papillae. There are four types of papillae, namely fungiform, filliform, foliate and circumvallate papillae (Meillgaard et al., 2007).

TouchThe sense of touch is divided into three different groups,

those being somesthesis, kinesthesis and chemesthesis (Kemp et al., 2009). Somesthetic sensation percieves force and particle size (Meilgaard et al., 2007). Nerve fibres in muscles, tendons and joints sense tension and relaxation kinaesthetically, giving rise to the perception of the sensory attributes of hardness and heaviness (Kemp et al., 2009). Chemesthesis is the chemical sensitivity of the skin and mucous membranes, allowing for the perception of hot, burning, tingling, cooling or astringent sensations (Green, 2004). Although, some texture assessments are performed visually, the main evaluation occurs in the mouth (Cook et al., 2005; Van Vliet et al., 2009).

SoundSound is sensed by millions of tiny hair cells in the ear

that are stimulated by the vibrations from sound waves (Kemp et al., 2009). The noise emitted by a food during chewing or biting gives an indication of the texture of the product, e.g. the crispness of a lettuce leaf, the crunchiness of an apple (Verhagen and Engelen, 2006). Acoustic emissions require a crack speed of ~300-500m/s for foods to be perceived as crispy (Luyten and Van Vliet, 2006).

SightStudies over the last 70 years or so have provided

empirical support for the claim that the color of a food/drink can exert a powerful influence on people’s flavor identification responses (e.g., DuBose et al. 1980; Hall 1958; Kanig 1955; Levitan et al. 2008; Moir 1936; Oram et al. 1995; Shankar et al. 2009; Stillman 1993; Zampini et al. 2007, 2008).

Guess?

Flavor Expectation based on ColorGreen - Lime (69%), apple (20%), melon (11%)Orange - Orange (91%), aniseed (5%), toffee (4%)Yellow - Lemon (89%), pear (5%), apple (4%), melon (2%)Blue - Spearmint (86%), raspberry (9%), cream soda (5%)Gray - Blackcurrant (53%), licorice (40%), cherry (4%),

aniseed (4%)Red - Strawberry (46%), raspberry (27%), cherry (27%)Colorless - Flavorless (51%), cream soda (16%), vanilla (15%),

aniseed (15%), spearmint (2%), melon (2%), pear (2%)

Zampini et al. (2007)

Keasat et al, 2004

Flavour Sensation and Components

Anne ThierrySTLO, INRA RennesJohn HannonTeagasc Food Research Centre, Moorepark, Cork

The uniqueness of many flavor substances appears to rely upon their ability to stimulate the olfactory organ. (Stanly and Yan, 2000)

ChemistryFlavor is caused by receptors in the mouth and nose

detecting chemicals found within food. These receptors respond by producing signals that are interpreted by the brain as sensations of taste and aroma. Certain taste and aroma combinations are characteristic of particular foods.

For example, a green apple tastes the way it does because the unique combination of chemicals found naturally within it are perceived by our mouths, noses and brains as the distinct blend of sweet and sour tastes and volatile aromas characteristic to the fruit.

Complex ChemistryOne natural flavor may contain hundreds or even

thousands of component substances, and some of these substances are present in minute quantities.

For example, one of the nine key aroma compounds found in pineapple is so potent that human subjects can detect it at only 6 ppt—the equivalent of a few grains of sugar in a 50m, 12 lane swimming pool.

Based onSensesStructure & Functional groupsNotesAcceptabilityOrigin of Flavor Compound

SenseTasteOdour

History RecapAristotle postulated in 350 BCE that the two most

basic tastes were sweet and bitter.Ayurveda, (5000BCE) an ancient Indian healing

science, has its own tradition of basic tastes, comprising sweet, salty, sour, pungent, bitter & astringent.

Ancient Chinese regarded spiciness as a basic taste.

TastesBitterSourSweetSaltUmmami

SourH+ ionsConcentration is proportional to taste intensity among

inorganic ionsOrganic ions are stronger than inorganic ions at same

concentration.Intensity of taste depends on the potential of the acidi.e. A weak acid taste as the same as a strong acid at same

concentration.Ex : Acetic acid, Citric acid, Tartaric acid , Lactic acid,

gamma amino butyric acid (decarboxylation of glutamic acid)

SaltNa + K, Ca & Mg salts of adipic, succinic, glutamic,

carbonic, lactic, hydrochloric, tartaric and citric acids.Monopotassium phosphate, adipic and glutamic acids

and potassium sulfate.Choline salt of acetic, carbonic, lactic, hydrochloric,

tartaric and citric acids.Potassium salt of guanylic and inosinic acidsSodium chloride is sweet at low (e.g., 0.020 M), but

salty at higher (0.050 M) concentrations.

SweetLactose, Glucose, Maltose, SuccroseGlycerolMannitol, Maltitol, XylitolKetones (after excercise)SaccharineAspartame

BitterPhenolic compound Cinnamic acidTannins to Green TeaGlycocidic compoundsNicotine to Pan Beetle MixCaffeine to CoffeeAlkali metalsInnorganic salts of Mg, Ca, NH4+ to hard water

UmmamiGlutamateGlutamic acidSpecific ribonucleotidesSalts of glutamic acidSalts of glutamate

MSGKGCaG

StructureEstersLinear terpenesCyclic terpenesAromaticAmines

EstersGeranyl acetate – RoseMethyl acetate – sweet nail polishMethyl propionate – Rum likeMethyl butyrate – pine appleEthyl acetate – wineEthyl butyrate – OrangeIsoamyl acetate – BananaPentyl butyrate – PearPentyl pentanoate - apple

Linear terpenesCompound Note Occurrence

Geraniol Rose/Flowery Lemon

Nerol Flowery Lemongrass

Citral Lemon Orange, Lime

Linalool Floral, sweet, woody Tea

Nerolidol Fresh bark Ginger

Cyclic compoundsName Note Occurrence

Limoene Orange Orange, Lemon

Camphor Camphor Camphor laurel

Menthol Menthol Mentha

Carvone Caraway, Spearmint Caraway

Terpineol Lilac Lilac, Cajuput

AromaticName Note Occurrence

Benzaldehyde Almond Almond

Eugenol Clove Clove

Cinnamaldehyde Cinnnamon Cassia, Cinnamon

Ethyl maltol Cooked fruit, Caramalized

Cooked Fruits

Vanillin Vanilla Vanilla

Anethole Anise Sweet basil

Anisole Anise Anise

Thymol Thyme Thyme

AmineName Note Occurrence

Trimethyl amine Fishy aroma Milk

Putrecine Rotting flesh Rotting flesh

Pyridine Fishy Fish

Indole Fecal Flowery Fecal Jasmine

Skatole Fecal Feces

Functional GroupAlcohol – Furaneol, Menthol, cis-HehanolAldehydes – Acetaldehyde, Cinamaldehyde,

CuminaldehydeEsters – Frutone, Ethyl methylphenylglycidateKetones - Oct-1-en-3-one (blood, metallic,

mushroom-like)Lactones - gamma-Decalactone intense peach flavor

gamma-Nonalactone coconut odorThiols - Allyl thiol (2-propenethiol; allyl mercaptan;

CH2=CHCH2SH) (garlic volatiles and garlic breath

Oholf Classification

NaturalArtificialNature Identical

Natural FlavoringsThe term natural flavor or natural flavoring means the

essential oil, oleoresin, essence or extractive, protein hydrolysate, distillate, or any product of roasting, heating or enzymolysis, which contains the flavoring constituents derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, seafood, poultry, eggs, dairy products, or fermentation products thereof, whose significant function in food is flavoring rather than nutritional. (FDA)

Natural Flavoring“Natural flavours” and “Natural Flavouring substances”

means flavour preparations and single substance respectively, acceptable for human consumption, obtained exclusively by physical processes from vegetables, sometimes animal raw materials, either in their natural state or processed for human consumption.

Nature Identical“nature-identical flavoring substances” means

substances chemically isolated from aromatic raw materials or obtained synthetically; they are chemically identical to substances present in natural products intended for human consumption, either processed or not. (FSSAI)

// Nature identical in EU but Artificial in US+

Artificial FlavoringThe term artificial flavor or artificial flavoring means

any substance, the function of which is to impart flavor, which is not derived from a spice, fruit or fruit juice, vegetable or vegetable juice, edible yeast, herb, bark, bud, root, leaf or similar plant material, meat, fish, poultry, eggs, dairy products, or fermentation products thereof. (FDA)

Artificial Flavoring“artificial Flavouring substances” means those

substances which have not been identified in natural products intended for human consumption either processed or not. (FSSAI)

SpicesThe term spice means any aromatic vegetable substance

in the whole, broken, or ground form, except for those substances which have been traditionally regarded as foods, such as onions, garlic and celery; whose significant function in food is seasoning rather than nutritional; that is true to name; and from which no portion of any volatile oil or other flavoring principle has been removed.(FDA)

Maillard browningThermal degradation of THiamine

Maillard BrowningWhen aldoses or ketoses are heated in solution with

amines, a variety of reactions ensue, producing numerous compounds, some of which are flavors, aromas, and dark-colored polymeric materials, but both reactants, disappear only slowly. The flavors, aromas, and colors may be either desirable or undersirable. They may be produced by frying, roasting, baking, or storage.

MBAmino acid + SugarMaillard reaction

Thiamine degradation

ThiamineThermal degradation of Thiamine produces Thiazoles

Introductionlong-term stability of flavor compounds in food product has

been a major concern in the food industry due to the complex interactions between key food ingredients (e.g., polysaccharides and proteins). (Tan et al 2014)

Flavor release is defined as a flavor compound transport process from the matrix to the vapor phase. Thus, a good knowledge of the physicochemical interactions occurring between flavor compounds and other major food components is required for the control of food flavoring and, more particularly, for understanding the phenomena involved in the release of aroma compounds in the mouth. In addition, the composition of the food matrix will determine the extent and type of flavor compounds it is inclined to bind.

Intro….The variations of food components in different food

matrices have contribute significantly to different interactions between the flavor compounds with other food components, which consequently influence the equilibrium headspace concentration of flavor compounds

InteractionsGum arabic, Xanthan gum – delayed flavour release(Miehosseini et al 2008)Fat content – Creamyness Smoothness Texture(Mao

et al, 2012 )Protein – Reversible and irreversible binding of

volatile compounds

InteractionsPhysical and Chemical Stability of FlavorEffects and Interactions of Lipids with Flavor

CompoundsEffects and Interactions of Carbohydrates with Flavor

CompoundsEffects and Interactions of Proteins with Flavor

Compounds

Physical and Chemical Stability of Flavor CompoundsMechanisms of flavor perceptionConcentration of flavor compounds in the receptorsFactors affecting partition and release of flavor

compounds in the mouthRate of volatilizationPhysical and chemical states of flavor compounds in

foodsBinding behavior of flavor compoundsFactors affecting partition coefficients

Effects and Interactions of Lipids with Flavor Compounds Increase flavor compounds adsorption and retention Decrease the partition coefficients Increase the flavor threshold concentrationCompounds Threshold Concentration (ppm)

Water OilOctanoic acid 5.8 350ã-decalactone 0.05 3.0Pentanal 0.07 0.3Hexanal 0.03 0.05

Effects and Interactions of Carbohydrates with Flavor CompoundsSoluble sugars increase the vapor pressures of volatile

compounds.Polysaccharides stabilize flavor compounds in foods during

processing due to entrapment, adsorption, reduced mass transport effects due to increased viscosity.

Cellulose adsorbs flavor compounds in intramolecular region.

Amylose forms inclusion complexes with aliphatic flavor compounds which fit inside the amylose helix.

The association constants with starch were 383, 930 and 2277 for limonene, methanol and decanal, respectively.

Effects and Interactions of Proteins with FlavorThe binding capacity of protein depends upon the

surface topography, porosity, and bulk density.Proteins bind aldehydes and ketones to differing

extents, indicating differences in intrinsic binding affinities, structural features of the protein, differences in available surface area.

Effects and Interactions of Proteins with FlavorThe Mechanisms of Flavor Compounds Interaction with

ProteinScatchard equation

v/[L] = nK-vK‘v’ is the number of moles of flavor compounds bound

per mole of protein.‘L’ is the molar concentration of flavor compounds.‘n’ is the total number of binding sites.‘K’ is the intrinsic binding constant.

Effects and Interactions of Proteins with FlavorKlotz equation

1/v = 1/n+1/nK[L]A plot of 1/v vs. 1/[L]Intercept = 1/n Slope = 1/nK

Stability of FlavorSeveral mechanisms are involved in interaction of flavor

compounds with food components.In lipid system, solubilization and rates of partitioning control the

interactions and partition coefficients, thus determine-s the rates of release.

In polysaccharide system, polysaccharides interact with flavor compounds by nonspecific adsorption and formation of inclusion compounds.

In protein system, protein involves adsorption, specific binding, entrapment, covalent binding and these mechanisms may account for the retention of flavor compounds.

Moisture affects diffusion and partition coefficients and macromolecular structures in the case of protein and polysaccharides and thereby affect the rate of release of flavor compound.

ProcessingThermalNon thermal

HIPEF

Thermal ProcessingIn-Container SterilizationRetortable pouchAseptic processing and Packaging

Rapid heating and CoolingPasteurization (LTLT, HTST,UHT)

Thermal ProcessingMaillard Reaction

FuranonesPyranonesPyrollesThiopenesHydroxyacetoneCycloteneDihydroxy acetoneHydroxy acetalGlyoxal

PyruvaldehydeGlycosaldehydeGlyceraldehydePyridinesPyrazinesOxazolesThiazolesPyrollesImidazoles

Thermal processingIncrease reaction kinetics and accelarates loss of

flavor compoundsCooked/Heated/Burnt and stale flavor of milk is due

to ketones formationButtery, milky, coconut like flavors in milk are due to

lactones formation from thermal breakdown of gamma and delta hydroxyacids

Thermal processingFuran derivatives formed when casein is undergoes

browning reaction with fructose at T>90oCAcetol and Acetonin gives off flavor to milk which has

been heated above 90oCChemical and rancid flavor increases in milk because

of increased amount of Butyric and hexanoic acids which is treated above 100oC

Hydrogen sulfide gives cooked flavor to milk and the intensity linearly corresponds to the intensity of heating.

Non Thermal ProcessingHigh Pressure ProcessingPulse Electric FieldPulsed X-Ray, Pulsed UVOhmic Heating, Radio Frequency, MicrowavePulsed LightOscillating Magnetic FieldsUltra FilterationIrradiation

IrradiationMeat

Roegg, bloody, fishy, brabecued corn, burnt, metalic, alcohol or acetic acid

Radiolysis of water into free radical species is the reasonGarlic

Diallyl disulfide reduced significantly (9<0.05) when treated with gamm radiation (wu et al, 1996)

GingerNo major changes in volatile concentration in gamma

irradiated gingerAfter 3 months decrease in a-zingiberene, B-bergamotene,

neral, geraneal and a-curcumene were significant (Wu and Yang 1984)

HIPEF40 kV/cm for 57 micro secondsReduces loss of flavor compounds during processing

compared to thermal pasteurization.

Compound 90oC – 30s 35kV/cm – 200 us

Limoene 15% 60%

Ethyl butyrate 26% 82%

Adapted from (Jia et al., 1996)

Destruction of Orange Flavor Compounds

HIPEFEx: Study shows that the PEF-processed tomato juice

retained more flavor compounds of trans-2-hexenal, 2-isobutylthiazole, cis-3-hexanol than thermally processed or unprocessed control tomato juice (P < 0.05).

PEF-processed juice had significantly lower non enzymatic browning and higher redness than thermally processed or control juice (P < 0.05). Sensory evaluations indicated that the flavor of PEF-processed juice was preferred to that of thermally processed juice (P < 0.01).

StoragePackaging material interactionTemperature (RT, Chilled, Refrigerated, Frozen)TimeVacuumMAP

Effects of Packaging MaterialsResidual compounds InteractionsDiffusivity of volatile flavor compoundsSorption of flavor compounds by packaging material

Case: Orange Juice in Low Density Poly Ethylene (LDPE) Polyethylene Terephthalate (PET) Polyvinylidine Chloride (PVC) Ethyl vinyl alchol copolymers (EVOH)

ExperimentD-LimoeneAlpha-pineneEthyl butyrateOctanal

The sorption of these compounds were measured during storage.

ResultsLDPE sorbed greater Limoene and pinene than other

packages (P<0.5)PET sorbed 30% less limonene than LDPE (p<0.5)PVC sobed 50% less limoene and pinene sorption

than LDPE (p<0.5)Ethyl butyrate and octanal sorptions were not

different for all packaging materials (p<0.5)

TimeAll initial flavor compounds depletes with timeCertain Off-Flavor compounds increases with time

Lipid oxidation and rancid flavorWeibull and PLSR distribution models suitable for

predicting retention of flavor compounds with time of storage.

Stale flavor from casein is from formation of carbonyl compounds.Benzaldehyde

Low TemperatureAllin content in garlic has been recorded to increase

when stored at 4oC

References1. A Taste For Flavour Characterization, Laboratory

Newshttp://www.labnews.co.uk/features/a-taste-for-flavour-characterisation

2. Andrew J. Taylor, Robert Linforth., Food Flavour Technology., John Wiley & Sons,2009.

3. Arie J. Haggen Smit., The Chemistry Of Flavour., Engineering and Science Monthly., 1949.

4. Arielle J. Johnson, Gregory D. Hirson, Susan E. Ebeler., Perceptual Characterization and Analysis of Aroma Mixtures Using Gas Chromatography Recomposition-Olfactometry., PLoS ONE. 2012

References6. Barbara d’Acampora Zellner , Paola Dugo, Giovanni

Dugo, Luigi Mondello, Gas chromatography–olfactometry in food flavour analysis, Journal of Chromatography A, Science Direct, 2007.

7. Bethany J. Hausch., Flavor Chemistry Of Lemon-Lime Carbonated Beverages., University Of Illinois, Urbana Campaign, 2010

8. Dr. David B. Min., Flavor Chemistry.,Ohio State University., Lecture., 2008

9. Factors affecting retention and release of flavour compounds in food carbohydrates., Naknean, P. and Meenune, M., International Food Research Journal, 2010.

References10. Fatma A. M. Hassan, Mona A. M. Abd El- Gawad, A. K. Enab.,

Flavour Compounds in Cheese (Review)., Research on Precision Instrument and Machinery., 2013.

11. Gary Reineccius., Sourcebook of Flavors.,Springer Science & Business Media, 1998. H.-D. Belitz · W. Grosch · P. Schieberle, Food Chemistry, Springer 2009

12. Identification of Potent Odorants in a Novel Nonalcoholic beverage Produced by Fermentation of Wort with Shiitake (Lentinula edodes)

13. Jida Zhang, Gang Cao, Yunhua Xia, Chengping Wen, Yongsheng Fan, Fast analysis of principal volatile compounds in crude and processed Atractylodes macrocephala by an automated static headspace gas chromatography-mass spectrometry, Pharmaconosy Magazine, Vol 10, Isseue 39, 2014

References14. Jon G. Wilkes, Eric D. Conte, Yongkyoung Kim, Manuel Holcomb, John B.

Sutherland, Dwight W., Miller., Sample preparation for the analysis of flavors and off-flavors in foods, Journal of Chromatography A, Elsevier, 2000.

15. Katherine A Thompson Witrick., Characterization of aroma and flavor compounds present in lambic (gueuze) beer., Virginia Polytechnic Institute and State University., 2012

16. Kathrin Ohla, Ulrike Toepe, Johannes le Coutre, Julie Hudry., Visual-Gustatory Interaction: Orbitofrontal and Insular Cortices Mediate the Effect of High-Calorie Visual Food Cues on Taste Pleasantness., PLoS ONE 2012.

17. Małgorzata Biniecka, Sergio Caroli., Analytical Methods for the qualntification of volatile aromatic compounds., Trends in Analytical Chemistry., 2011.

References17. Malika Auvray and Charles Spence., The

multisensory perception of flavor., Conciousness and Cognition., Elsevier 2008.

18. Maria E.O. Mamede a, Gla´ucia M. Pastore; Study of methods for the extraction of volatile compounds from fermented grape must; Journal of Food Chemistry; 2005.

19. Mariaca R., Bosset J.o., Instrumental Analysis of volatils (flavour) compounds in milk and dairy products(a review)., Swiss federal dairy research station., 1997.

20.Michael Dennis Sharp, B.S.., Analysis of Vanilla Compounds in Vanilla Extracts and Model Vanilla Ice Cream Mixes Using Novel Technology., Ohio State University. 2009.

References21. Michael H. Tunick , Susan K. Iandola and Diane L. Van Hekken.,

Comparison of SPME Methods for Determining Volatile Compounds in Milk, Cheese, and Whey Powder., Foods., 2013.

22. Michael Moss, The Newyork Times, The Extraordinary Science of Addictive Junk Food, http://www.nytimes.com/2013/02/24/magazine/the-extraordinary-science-of-junk-food.html?pagewanted=all&_r=0

23. Naknean, P. and Meenune, M., Factors affecting retention and release of flavour compounds in food carbohydrates., International Food Research Journal., 2010.

24. O.Bensebia , D.Barth, A.Dahmani Supercritical Carbon Dioxide Extraction Of Rosemary Comparison With Steam Distillation And Hydrodistillation., University Of Algeria. 2005

For their kind help

Thank you!!!Dr.K.Aparna, Assistance Professor – Dept of Food and

Nutrition,, PG&RC, PJTSAU.Socialist Democratic Secular Govt of India and ICCR,

For their courtesy of Sponsoring me to study here.PJTSAU, Central Library. For lending Books and

Internet fascilityMy Class Mates.You all for your kind attention

Questions

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