Flavor Chemistry 820 The Ohio State University Food Science and Technology Instructor : Professor David B. Min
General Objectives • Roles of flavor chemistry in food quality, food products development and flavor research • Chemical structures and formation of flavor compounds • Organic, bio, and analytical chemistries involved in flavor research • Effects of processing, packaging and storage conditions on the flavor quality and stability of foods • Current research related to flavor.
Upon completion of this course, students should be able to: • 1. Understand the chemical reactions involved in • flavor compounds formation in natural and • processed food. • 2. Comprehend the effects of food components, • processing parameters and storage conditions on • flavor quality of foods. • 3. Understand principles, techniques and • applications of analytical instruments involved in • flavor analysis.
4. Optimize ingredient concentration, processing • parameters, packing materials and storage • conditions for optimum quality and stability. • 5. Develop simple research programs of flavor chemistry. • 6. Specify the flavor qualities of raw ingredients.
Evaluation • Midterm Examinations (2) 40% • Final Examination 30% • Home Work and Class Participation 30%
1. Introduction • I. Definition of Flavor • II. Classification of Food Flavor • III. Scope of Flavor Chemistry • 1.Chemical compounds responsible for food flavor • 2.Flavor of foods • 3.Reconstitution of flavor compounds • 4.Precursors of the flavor compounds • 5.Mechanism for the formation of flavor compounds and precursors in foods • 6.Relationship between physical properties and its flavor • IV. Objectives of Flavor Chemistry
2. Isolation and Separation of Flavor Compounds • I. Objective • II. Prerequisites • III. Apparatus for Isolation • 1.Headspace analysis • 2.Continuous solvent extraction • 3.Steam distillation and continuous • solvent extraction • IV. Extraction and Concentration • V. Preliminary and Final Fractionation • VI. Dynamic Headspace analyzer • V. Solid Phase Microextraction Analysis
3. Identification of Flavor Compounds by Spectrometric Methods • Introduction of Spectrometric Analyses • Ultra Violet Spectrometry • Infrared Spectrometry • Nuclear Magnetic Resonance Spectrometry • V. Mass Spectrometry • 1.Furans • 2.Pyrroles • 3.Thiophenes • 4.Pyridines • 5.Pyrazines
4. Manufacture of Food Flavor I. Natural or Imitation Flavor II. Problems of Using Natural Flavor III. Disadvantages of Using Imitation Flavor IV. Advantages of Imitation Flavor V. Methods in Synthetic Flavor Reconstitution
5. Chemistry of Flavor Precursors • I. Flavor Compounds from Carbohydrates and • Proteins • Thermal Degradation of Vitamin B1 • Lipid Oxidation • IV. Flavor Generated from Enzymatic Method, Microbiological Reaction, and Biogenesis
6. Flavor Chemistry of Dairy Products • I. Milk Flavor • 1. Oxidized flavor • 2. Rancid flavor • 3. Heated flavor • 4. Microbiological flavor • 5. Absorbed flavor • 6. Sunlight flavor • II.Cheese Flavor • 1. Isolation, separation and identification of cheese flavor • 2. Biological pathways of fat in cheese flavor • 3. Reaction products of methionine • 4. Biochemical pathways of cheese flavor formation from protein • 5. 2-Butanone and 2-Butanol formation from diacetyl and acetone • 6. Biochemical pathways of cheese flavor formation from lactose
7. Flavor Chemistry of Meat • I. Introduction • II. Effect of Psychrotropic Bacteria on the Volatile Compounds of Raw Beef • 1. Introduction • 2. Volatile compounds of aseptic raw ground beef • 3. Effects of psychrotropic bacteria on the volatile compounds of aseptic raw ground beef • III. Isolation, Separation, and Identification of Roast Beef Flavor Simulated Meat Flavor Formation
8. Interaction of Flavor Compounds with Food Compounds • Physical and Chemical Stability of Flavor Compounds in Lipid Food • Effects and Interactions of Carbohydrates with Flavor Compounds • III. Interactions of Proteins with Flavor Compounds
9. Interactions between Packaging and Flavor Compounds • I. Effects of Packaging Materials on the Flavor Quality of Food • II. Sorption of Orange Flavor Compounds by Packaging Materials
10. Favor Compounds and Solvent Interaction • Commercial Cherry Flavor and Solvent Interaction • II. Acetal Formation
Introduction I. Definition of Flavor Flavor is the sensation produced by a material in the mouth, perceived principally by the senses of taste and smell, and also by the general tactile and temperature receptors in the mouth. Flavor also denotes the sum of the characteristics of the material which produces that sensation. Flavor is one of the important qualities of foods which are decisive in the selection, acceptance, and ingestion of a food.
StimulusSensesSensory Response Taste Food Flavor Odor
Scope of Flavor Chemistry 1. Chemical compounds responsible for food flavor 1) Even distribution: Brandy 2) Star compound: A star compound can not be identical to the total true flavor but is close and can not produce the true flavor without the star compound.
Vanilla: 4-Hydroxy-3-methoxy-benzolaldehyde C H O O C H 3 O H
Reversion Rancid Flavor of Soybean Oil: 2-Pentylfuran and 2-Pentenylfuran ( C H ) C H O 2 4 3
Flavor of Foods 1) Desirable flavor Orange juice Potato chips Roast beef 2) Undesirable flavor (off-flavor) Oxidized Stale Rancid Warmed-over
1 11 10 17 3 13 Total GC peak area in 0 kGy: 2.99 107 16 15 6 8 9 12 5 7 14 Gas chromatogram of Orange Juice Flavor
Precursors of Flavor Compounds Linoleate 2-pentylfuran
2-Pentenylfurans in Beany Soybean Oil 0 ppm No reversion flavor 5 ppm trans-2-heptenal 2-pentylfuran 2-pentenlyfuran Strong reversion flavor
1) Non-enzymatic reaction Precursor of beef flavor can be isolated as a white fluffy powder. White fluffy powder Oil Water Broil stew Beef broth flavor Amino acid + Sugar Maillard reaction
2) Enzymatic reaction Processed banana no fresh banana flavor enzyme extracted from banana peel Fresh banana flavor
Mechanisms for Flavor Compounds Formation and Precursors in Foods • 1) Volatile flavors developed in most food plants mainly at • the ripening stage - the result of plant metabolism through enzymatic reaction. • 2) Raw meat must be heated before it develops any • organoleptically acceptable flavor. • meat flavor (boiled beef) • 3, 5-Dimethyl-1,2,4-trithiolane 2 1 S S 3 5 H C C H S 3 3 4
Model Studies S S CH CHO + H S 3 2 S ( S ) CH C H S C H C H H S + CH CHO 3 3 3 2 S H S H ( O ) S H C C H 3 3 S S
C H C H O , H S are precursors Therefore, 3 2 H S C C C O O H Beef flavor (reaction flavor) N H 2 Apply the knowledge we gained from the mechanism and precursor studies to processed food. a. Enhance the desirable food flavor. b. Elimination of the undesirable food flavor. c. Application of heated model system to processed foods.
Relationship between Physical Properties of Compound and Flavor B.P.(0C) Solubility in H2O Threshhold of smell (g/ 100 ml) (ppm) n-propanol 61.0 20.0 0.17 n-butanol 75.7 4.0 0.07 n-hexanal 131.0 0.5 0.03 CH3-S-CH3 37.5 insoluble 0.01
Odor Threshold (ppm) in Water 2-t-pentenal 2.3 2-t-hexanal 10.0 2-t-heptanal 14.0 2-t-octenal 17.0 2-t-nonenal 23.2 2-t-decenal 33.8 2-t-undecenal 150.0 The series has an increase b.p. and decreased solubility in H2O
Effect of Medium on the Vapor Compositions of Flavor Compounds Headspace Analysis Compound Water Corn oil (200ppm) (peak area) (peak area) acetone 10 47 2-butanone 14 11 2-pentanone 22 5.7 2-hexanone 29 2.7 2-heptanone 24 0.7