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Flavors - An Overview


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This is a summary of Flavor Chemistry in a shortest form

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Flavors - An Overview

  1. 1. Types of Flavors Thermally Induced Flavors Stability in Food Systems Effects of processing and Storage
  2. 2. Contents Introduction Types of Flavors Thermally Induced Flaovrs Stability in Food Systems Effects of processing and Strage
  3. 3. Flavor Perception Chemistry
  4. 4. Introduction The 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
  5. 5. Importance Flavor 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)
  6. 6. Flavor Perception Gustatory, 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
  7. 7. Multisensory perception Although, 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).
  8. 8. Smell Aroma 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).
  9. 9. Taste The 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).
  10. 10. Touch The 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).
  11. 11. Sound Sound 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).
  12. 12. Sight Studies 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).
  13. 13. Guess?
  14. 14. Flavor Expectation based on Color Green - 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)
  15. 15. Keasat et al, 2004
  16. 16. Flavour Sensation and Components Anne Thierry STLO, INRA Rennes John Hannon Teagasc Food Research Centre, Moorepark, Cork
  17. 17. The uniqueness of many flavor substances appears to rely upon their ability to stimulate the olfactory organ. (Stanly and Yan, 2000)
  18. 18. Chemistry Flavor 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.
  19. 19. Complex Chemistry One 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.
  20. 20. Based on Senses Structure & Functional groups Notes Acceptability Origin of Flavor Compound
  21. 21. Sense Taste Odour
  22. 22. History Recap Aristotle 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.
  23. 23. Tastes Bitter Sour Sweet Salt Ummami
  24. 24. Sour H+ ions Concentration is proportional to taste intensity among inorganic ions Organic ions are stronger than inorganic ions at same concentration. Intensity of taste depends on the potential of the acid i.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)
  25. 25. Salt Na+ 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 acids Sodium chloride is sweet at low (e.g., 0.020 M), but salty at higher (0.050 M) concentrations.
  26. 26. Sweet Lactose, Glucose, Maltose, Succrose Glycerol Mannitol, Maltitol, Xylitol Ketones (after excercise) Saccharine Aspartame
  27. 27. Bitter Phenolic compound Cinnamic acid Tannins to Green Tea Glycocidic compounds Nicotine to Pan Beetle Mix Caffeine to Coffee Alkali metals Innorganic salts of Mg, Ca, NH4+ to hard water
  28. 28. Ummami Glutamate Glutamic acid Specific ribonucleotides Salts of glutamic acid Salts of glutamate MSG KG CaG
  29. 29. Structure Esters Linear terpenes Cyclic terpenes Aromatic Amines
  30. 30. Esters Geranyl acetate – Rose Methyl acetate – sweet nail polish Methyl propionate – Rum like Methyl butyrate – pine apple Ethyl acetate – wine Ethyl butyrate – Orange Isoamyl acetate – Banana Pentyl butyrate – Pear Pentyl pentanoate - apple
  31. 31. Linear terpenes Compound Note Occurrence Geraniol Rose/Flowery Lemon Nerol Flowery Lemongrass Citral Lemon Orange, Lime Linalool Floral, sweet, woody Tea Nerolidol Fresh bark Ginger
  32. 32. Cyclic compounds Name Note Occurrence Limoene Orange Orange, Lemon Camphor Camphor Camphor laurel Menthol Menthol Mentha Carvone Caraway, Spearmint Caraway Terpineol Lilac Lilac, Cajuput
  33. 33. Aromatic Name 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
  34. 34. Amine Name Note Occurrence Trimethyl amine Fishy aroma Milk Putrecine Rotting flesh Rotting flesh Pyridine Fishy Fish Indole Fecal Flowery Fecal Jasmine Skatole Fecal Feces
  35. 35. Functional Group Alcohol – Furaneol, Menthol, cis-Hehanol Aldehydes – Acetaldehyde, Cinamaldehyde, Cuminaldehyde Esters – Frutone, Ethyl methylphenylglycidate Ketones - Oct-1-en-3-one (blood, metallic, mushroom-like) Lactones - gamma-Decalactone intense peach flavor gamma-Nonalactone coconut odor Thiols - Allyl thiol (2-propenethiol; allyl mercaptan; CH2=CHCH2SH) (garlic volatiles and garlic breath
  36. 36. Oholf Classification
  37. 37. Natural Artificial Nature Identical
  38. 38. Natural Flavorings The 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)
  39. 39. 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.
  40. 40. 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+
  41. 41. Artificial Flavoring The 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)
  42. 42. 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)
  43. 43. Spices The 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)
  44. 44. Maillard browning Thermal degradation of THiamine
  45. 45. Maillard Browning When 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.
  46. 46. MB Amino acid + SugarMaillard reaction
  47. 47. Thiamine degradation
  48. 48. Thiamine Thermal degradation of Thiamine produces Thiazoles
  49. 49. Introduction long-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.
  50. 50. 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
  51. 51. Interactions Gum 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
  52. 52. Interactions Physical and Chemical Stability of Flavor Effects and Interactions of Lipids with Flavor Compounds Effects and Interactions of Carbohydrates with Flavor Compounds Effects and Interactions of Proteins with Flavor Compounds
  53. 53. Physical and Chemical Stability of Flavor Compounds Mechanisms of flavor perception Concentration of flavor compounds in the receptors Factors affecting partition and release of flavor compounds in the mouth Rate of volatilization Physical and chemical states of flavor compounds in foods Binding behavior of flavor compounds Factors affecting partition coefficients
  54. 54. Effects and Interactions of Lipids with Flavor Compounds  Increase flavor compounds adsorption and retention  Decrease the partition coefficients  Increase the flavor threshold concentration Compounds Threshold Concentration (ppm) Water Oil Octanoic acid 5.8 350 ã-decalactone 0.05 3.0 Pentanal 0.07 0.3 Hexanal 0.03 0.05
  55. 55. Effects and Interactions of Carbohydrates with Flavor Compounds Soluble 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.
  56. 56. Effects and Interactions of Proteins with Flavor The 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.
  57. 57. Effects and Interactions of Proteins with Flavor The Mechanisms of Flavor Compounds Interaction with Protein Scatchard 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.
  58. 58. Effects and Interactions of Proteins with Flavor Klotz equation 1/v = 1/n+1/nK[L] A plot of 1/v vs. 1/[L] Intercept = 1/n Slope = 1/nK
  59. 59. Stability of Flavor Several 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.
  60. 60. Processing Thermal Non thermal HIPEF
  61. 61. Thermal Processing In-Container Sterilization Retortable pouch Aseptic processing and Packaging Rapid heating and Cooling Pasteurization (LTLT, HTST,UHT)
  62. 62. Thermal Processing Maillard Reaction Furanones Pyranones Pyrolles Thiopenes Hydroxyacetone Cyclotene Dihydroxy acetone Hydroxy acetal Glyoxal Pyruvaldehyde Glycosaldehyde Glyceraldehyde Pyridines Pyrazines Oxazoles Thiazoles Pyrolles Imidazoles
  63. 63. Thermal processing Increase reaction kinetics and accelarates loss of flavor compounds Cooked/Heated/Burnt and stale flavor of milk is due to ketones formation Buttery, milky, coconut like flavors in milk are due to lactones formation from thermal breakdown of gamma and delta hydroxyacids
  64. 64. Thermal processing Furan derivatives formed when casein is undergoes browning reaction with fructose at T>90o C Acetol and Acetonin gives off flavor to milk which has been heated above 90o C Chemical and rancid flavor increases in milk because of increased amount of Butyric and hexanoic acids which is treated above 100o C Hydrogen sulfide gives cooked flavor to milk and the intensity linearly corresponds to the intensity of heating.
  65. 65. Non Thermal Processing High Pressure Processing Pulse Electric Field Pulsed X-Ray, Pulsed UV Ohmic Heating, Radio Frequency, Microwave Pulsed Light Oscillating Magnetic Fields Ultra Filteration Irradiation
  66. 66. Irradiation Meat Roegg, bloody, fishy, brabecued corn, burnt, metalic, alcohol or acetic acid Radiolysis of water into free radical species is the reason Garlic Diallyl disulfide reduced significantly (9<0.05) when treated with gamm radiation (wu et al, 1996) Ginger No major changes in volatile concentration in gamma irradiated ginger After 3 months decrease in a-zingiberene, B-bergamotene, neral, geraneal and a-curcumene were significant (Wu and Yang 1984)
  67. 67. HIPEF 40 kV/cm for 57 micro seconds Reduces loss of flavor compounds during processing compared to thermal pasteurization. Compound 90o C – 30s 35kV/cm – 200 us Limoene 15% 60% Ethyl butyrate 26% 82% Adapted from (Jia et al., 1996) Destruction of Orange Flavor Compounds
  68. 68. HIPEF Ex: 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).
  69. 69. Storage Packaging material interaction Temperature (RT, Chilled, Refrigerated, Frozen) Time Vacuum MAP
  70. 70. Effects of Packaging Materials Residual compounds Interactions Diffusivity of volatile flavor compounds Sorption 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)
  71. 71. Experiment D-Limoene Alpha-pinene Ethyl butyrate Octanal The sorption of these compounds were measured during storage.
  72. 72. Results LDPE 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)
  73. 73. Time All initial flavor compounds depletes with time Certain Off-Flavor compounds increases with time Lipid oxidation and rancid flavor Weibull 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
  74. 74. Low Temperature Allin content in garlic has been recorded to increase when stored at 4o C
  75. 75. References 1. A Taste For Flavour Characterization, Laboratory News 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
  76. 76. References 6. 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
  77. 77. References 10. 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
  78. 78. References 14. 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.
  79. 79. References 17. 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.
  80. 80. References 21. 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, 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
  81. 81. For their kind help
  82. 82. 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 fascility My Class Mates. You all for your kind attention
  83. 83. Questions Please!!!