What is Flavor

1. What is Flavor? A sensation produced by a material taken in the mouth, perceived principally by the senses of taste and smell, and also by the general pain, tactile, and temperature receptors in the mouth. Flavor also denotes the sum of the characteristics of the material which produces that sensation

2. Sensory Properties

3. Food Flavors Desirable flavor orange juice potato chips roast beef Undesirable flavor (off-flavor) oxidized stale rancid warmed-over

4. Objectives of Flavor Chemistry To understand the chemical composition of natural flavors and the mechanism of their formation To retard or prevent the development of the off-flavors in foods To restore the fresh flavor to a processed food To improve the flavor of food by the addition of synthetic flavor To produce new foods with special flavor such as potato chip flavor To improve flavor by the acceleration of reactions which produce desirable flavor compound To assist geneticist to breed food raw material with improved flavor compounds or flavor precursors To specify raw material and to control quality of food products

5. Classification of Flavors

6. Compounds Responsible for Flavor

7. Compounds Responsible for Flavor(continued)

8. Flavors of Acids Formic Acetic Propionic Butyric Hexanoic Octanoic Decanoic Lauric Myristic Palmitic Acid, pungent Acid, vinegary Acid, rancid, cheesy Acid, rancid Sweaty, goaty Rancid Waxy Tallowy Soapy, cardboard Soapy

9. Formation of Flavor Compounds Enzymatic Volatile flavors developed in most food plants mainly at the ripening stage Non-Enzymatic Raw meat must be heated (Maillard browning) before it develops any organoleptically acceptable flavor

10. ISOLATION AND SEPARATION OF FLAVOR COMPOUNDS Selection of �Good flavor sample� Isolation of Volatile Flavor Compounds Extraction and Concentration Fractionation Preparation of pure compound Identification Synthesis Reconstitution of the flavor

11. Fractionation of Flavor Compounds

12. Final Fractionation of Flavor Compounds Gas-Liquid Chromatography (GC) Sample: as concentrate as possible GC-Mass Use capillary column Identification of the important peaks by mass spectrometry

13. Spectrometric Methods for Flavor Identification Ultra Violet Spectrometry Infrared Spectrometry Nuclear Magnetic Resonance Spectrometry Mass Spectrometry

14. Pyrazine Formation(cocoa, coffee, french fries, roast beef)

15. Formation of Trimethyloxazole from Diacetyl, Acetaldehyde, and Ammonia

16. Trimethylthiazole Formation(nutty, sulfur )

17. Formation of Furans

18. Generation of Diacetyl in Butter

19. Generation of Banana Flavor

20. Physical and Chemical States of Flavor Compounds in Foods Flavor compounds may be dissolved, adsorbed, absorbed, or entrapped in food components depending upon functional groups, molecular size, shape and volatility, and chemical properties of the components in the food.

21. Effects of Selective Binding on Flavor Perception The selective binding of one flavor compound of a blend to food components or packaging material can markedly alter the overall flavor impact. Binding limits its volatilization and diffusion and hence impairs its immediate perception as a components of an overall flavor when food is taken into the mouth.

22. Factors Affecting Partition Coefficients Temperature The presence of soluble solutes and nonsoluble materials Diffusion rates in the aqueous phase Physical retention of flavor compound

23. Interactions of Flavor Compounds with Food Components In lipid systems, solubilization and rates of partitioning control the interactions and partition coefficients, thus determines the rates of release In polysaccharide systems, polysaccharides interact with flavor compounds by nonspecific adsorption and formation of inclusion compounds In protein systems, 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

24. Interactions Between Flavor Compounds and Food Components