12. Deep Fat Frying Chemistry
-
Upload
ogen-kapitan -
Category
Documents
-
view
125 -
download
9
Transcript of 12. Deep Fat Frying Chemistry
![Page 1: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/1.jpg)
CHEMICAL REACTIONS of DEEP-FAT FRYING OF FOODS
![Page 2: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/2.jpg)
Deep-Fat Frying
• Deep-Fat Frying is a process of immersing food in hot oil.
• A process of cooking and drying produces unique fried
foods by simultaneous heat and mass transfer .
• Flavor compounds are formed and retained in a crisp crust
of food
![Page 3: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/3.jpg)
Annual Sales of Deep Fat Fried Foods in U.S.
Food Industries Restaurants
5109 pounds 2109 pounds
$ 15 billion per year
Sales of fried foods in U.S. increased by 35% from 1987 to 1996.
(Snack Food Association, 1997).
![Page 4: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/4.jpg)
Physical and Chemical Reactions during Deep-Fat Frying
![Page 5: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/5.jpg)
Physical Changes of Deep-Fat Frying
• Viscosity Increase
• Thickening of oil
• Decrease of interfacial tension
• Increase of density
• Increase of the specific heat
![Page 6: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/6.jpg)
Products Oil Contents (%)
Potato chips 33-38
Corn chips 30-38
Tortilla chips 23-30
Doughnuts 20-25
Frozen food 10-15
French fries 10-15
Oil Contents in Deep-Fat Fried Foods
![Page 7: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/7.jpg)
• Formation of flavor
• Flavor stability and quality changes
• Color and texture of the fried foods changes
• Nutritional changes
Chemical Changes of Deep-Fat Frying
![Page 8: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/8.jpg)
• Hydrolysis
• Oxidation
• Polymerization
• Pyrolysis
Chemical Reactions in Frying Oil
![Page 9: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/9.jpg)
Chemical Reactions in Deep-Fat Frying of Foods
Volatile Flavor Compounds:
220 volatile compounds have been identified.
![Page 10: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/10.jpg)
Deep-Fat Fried Flavor
4-hydroxy-2-nonenoic acid, lactone4- hydroxy-3-nonenoic acid2,4-decadienalnutty, fried fat notes plus a butter-like note
Some of volatile compounds formed in deep-fat frying condition are known as toxic compounds.
Example:1,4- Dioxane
Benzene Toluene Hexyl-benzene
![Page 11: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/11.jpg)
Volatile Products from Deep-Fat Frying
Acids -- Saturated AcidsUnsaturated acids (cis, trans)Hydroxy acids
Hydrocarbons – Saturated hydrocarbons Unsaturated hydrocarbons
AlcoholsAldehydes - Saturated
UnsaturatedKetonesEstersAromatic CompoundsLactonesMiscellaneous: 2-Pentyl furan
1,4-Dioxane
![Page 12: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/12.jpg)
Aromatic Compound Formation
C H3 C H C H C H C H C H2 (C H2)n C H3
O 2
C H3 C H C H C H C H C H (C H2)n C H3
O O H+ R
- ROH
+ OR
C H3 C H C H C H C H C H (C H2)n C H3
O
![Page 13: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/13.jpg)
C H 3 C H C H C H C H C (C H 2)n C H3
O
CHC H
C (C H2)n C H3
C HC H
O
C H3
(C H 2)n
- H 2O
C H 3
![Page 14: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/14.jpg)
Aromatic Compound Formation
C H3 (C H2)3 C H2 C H C H C H2 C H C H (C H2)7 C O O R
O 2
C H2
C (C H2)7 C O O R
O
C H2 (C H2)2 C H3
C H2
C H2
(C H2)6 C O O R
(C H2)2 C H3
- H O2
![Page 15: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/15.jpg)
Formation of -2 Nonelactone
C H3 C H2 C H2 C H2 C H2 C H C H C H2 C H C H
C H3 C H2 C H2 C H2 C H2 C H C H
C H3 C H2 C H2 C H2 C H2 C H C H
C H3 C H2 C H2 C H 2 C H2 C H C H
.
C H C H C H
O O H
C H C H
C H C H O H
R
R
+ OH.
![Page 16: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/16.jpg)
C H 3 C H2 C H 2 C H 2 C H 2 C H C H C H 2 C
O
H
C H3 C H2 C H2 C H2 C H2 C H
O H
C H
C H 3 C H2 C H 2 C H 2 C H 2 C H C H. CC H
O
H
CC H
O
.
+ .OH
C H3 C H2 C H2 C H2 C H2 C H
O H
C H CC H O H
O
-H 2O
-2-Nonelactone
O2
- H
C H3
C H2
C H2
C H2
C H2
C H C H C H C H O H
![Page 17: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/17.jpg)
Effect of Methionine Analogs on Potato Chip-Flavor in Deep-Fat Frying.
Compounds Structures Flavor Characteristics
D-MethionineL-MethionineDL-Methionine
CH3-S-CH2-CH2-CH(NH2)COOH
Good potato chip-like
S-Methyl-L-Cysteine
CH3-S-CH2-CH(NH2)COOH
Good potato chip-like
Methionine Hydroxy Analog
CH3-S-CH2-CH2-CH(OH)COOH
Obnoxious(cooked turnip)
S-Carboxymethyl-L-Cysteine
HOOC-CH2-S-CH2-CH(NH2)COOH
Obnoxious(cooked turnip)
![Page 18: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/18.jpg)
Polymer Formation
Carbon-Carbon Bond: A. Vinyl Type
C
CC
C
C
![Page 19: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/19.jpg)
B. Diels Alder Type
C C
H
C C C
H H H H
- .H
C
H
H
HHHH
CCCC
C C
H H
C
H
HH
H CC
C
H
C
HC C
Intermolecularly or Intramolecularly
Carbon-Carbon Bond:
![Page 20: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/20.jpg)
Carbon-Oxygen Bond
Through peroxide group – formed by autoxidation.
This can be formed intermolecularly or intramolecularly.
Through ether linkage – formed at high temperature.
O
O
O
O
![Page 21: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/21.jpg)
Polymers Formed during Deep-Fat Frying
The 74 hrs. deep-fat frying conditions
Trilinolenin 26.3% Trilinolein 10.0% Triolein 10.8% Tristearin 4.2%
![Page 22: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/22.jpg)
Types of Polymers
Trilinolein Monocyclic, Nonpolar C-C Dimer 4.9%
Noncyclic, Polar C-C Dimer 2.8%
Trimers - C-C, 8.4%
Trimers - 2 C-O, or 1 C-C, 1 C-O 4.9%
COOR
COOR
COOR
COOR
OH
OH
![Page 23: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/23.jpg)
Diels-Alder Reaction
C O O H
C O O H
C O O H
C O O H
C O O H
C O O H
![Page 24: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/24.jpg)
C H2
C H
C H2
C H2
C H
C H2
Dimerization Between Two Acyl Groups in the Same Triglyceride or
Dimerization Between Two Acyl Groups in Two Triglycerides
Dimerization
![Page 25: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/25.jpg)
Composition of Oxidized and Polymerized Materials Formed during Simulated Deep-Fat Frying at 185C for 74 Hrs.
TRILINOLEIN
TRIOLEIN
TRISTEARIN
Cyclic Dimers Carbon-to-Carbon Linkages 4.9 0.0 0.0
Noncyclic DimerCarbon-to-Carbon Linkages
2.8 3.4 0.7
Trimers Two Carbon-to-Carbon Linkages
8.4 0.3 0.4
4.9 1.2
Dimers and Trimers Carbon-to-Carbon or Oxygen Linkages
6.2
![Page 26: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/26.jpg)
Biological Effects of Used Frying Oil
• A slight depression in growth to very poor growth
• Diminished feed efficiency
• Increased liver, kidney and heart sizes
• Fatty tissues of liver, kidney and heart organs
• Liver enzymes such as thiokinase and succinyldehydrogenase
had lower activity
• The evidence of carcinogenicity (in highly abused frying oil)
![Page 27: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/27.jpg)
Safety
Under Good Practice of Deep-Fat Frying:
Fats are not nutritionally damaged
![Page 28: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/28.jpg)
Frying Oil Analyses by Liquid Chromatography
![Page 29: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/29.jpg)
![Page 30: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/30.jpg)
![Page 31: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/31.jpg)
Thermal Oxidation Effect on Linoleic Acid Concentration
Levels of Linoleic Acida
FAT FRESH OXIDIZED
Corn oil 61.0 1.1
Olive oil 7.7 Trace
Learb 21.7 1.1
Lard 10.7 1.4
a Expressed as % of total fatty acids.
b Lear = Low erucic acid rapeseed oil.
![Page 32: 12. Deep Fat Frying Chemistry](https://reader033.fdocuments.us/reader033/viewer/2022061105/543f76dcb1af9f620a8b47aa/html5/thumbnails/32.jpg)
Toxicity Symptoms of Highly Heat-Abused Oils to Laboratory Animals
Irritation of the digestive tractOrgan enlargement (kidney & liver)Growth depression
Carcinogenic properties
Good Practice of Deep-Fat Frying
Fats are not nutritionally damaged.