Flavor Chemistry 820

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Flavor Chemistry 820

• The Ohio State University
• Food Science and Technology
• Instructor Professor David B. Min

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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.

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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.
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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.
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Evaluation
Midterm Examinations (2) 40 Final
Examination 30 Home Work
and Class Participation 30
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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
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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
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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

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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
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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

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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
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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
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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

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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
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10. Favor Compounds and Solvent Interaction

• Commercial Cherry Flavor and Solvent Interaction
• II. Acetal Formation

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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.
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Stimulus Senses Sensory Response
Taste Food Flavor Odor
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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.
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Almond Benzoaldehyde
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Vanilla 4-Hydroxy-3-methoxy-benzolaldehyde
C
H
O
O
C
H
3
O
H
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Reversion Rancid Flavor of Soybean Oil
2-Pentylfuran and 2-Pentenylfuran
(
C
H
)
C
H
O
2
4
3
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Flavor of Foods
1) Desirable flavor Orange juice
Potato chips Roast beef 2)
Undesirable flavor (off-flavor)
Oxidized Stale Rancid
Warmed-over
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Gas chromatogram of Orange Juice Flavor
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Precursors of Flavor Compounds
Linoleate 2-pentylfuran
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2-Pentenylfurans in Beany Soybean Oil
0 ppm
             
     
     
No reversion flavor
5 ppm
trans-2-heptenal
2-pentylfuran
2-pentenlyfuran
Strong reversion flavor
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Mass Spectrum of 2-Pentenylfuran
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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
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2) Enzymatic reaction Processed banana
no fresh banana flavor
enzyme extracted from banana
peel Fresh banana flavor
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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
C
H
H
C
S
3
3
4
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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
C
H
H
C
3
3
S
S
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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.
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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
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Odor Threshold (ppm) in Water
2-t-pentenal 2.3 2-t-hexanal 10.0 2-t-hep
tanal 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
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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
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