Nutritional Changes and Toxicants Formed During Food Processing

Question 1

Food Processing Approach

Answer 1

• Thermal processing
• Blanching and pasteurization
• Sterilization
• Refrigerated storage
• Freezing and frozen food storage
• Dehydration
• Physical processes (Milling, extrusion etc.)
• Irradiation

Question 2

Factors that deteriorate foods

Answer 2

• Nutrients in foods

• Microbial

• Environmental exposure

Question 3

Purpose of Food Processing

Answer 3

1. Preservation
2. Increase Palatability
3. Toxin Removal
4. Quality and Marketing
5. Improves food nutritional value

Question 4

Purpose of Food Processing (Preservation)

Answer 4

1) BHA & BHT
• Prevent rancidity in fat and oil
• Some countries have banned BHT – carcinogen in rats
2) Antimicrobes
• Nitrofurans, Chloramphenicol – Carcinogen, mutagen
• Benzoic acid and Sodium Benzoate – long term effects : Weight loss, enlargement of liver and kidney etc.

3) Salting, pasteurization, drying and etc.

Question 5

Purpose of Food Processing (Increase Palatability)

Answer 5

1) Fat, oil, salt, sugar, flavor enhancer
• CVD, diabetes, food intolerance, etc.

2) Polyphosphate
• 1950’s – injected into meat and fish to increase water content.
• Hydrolized into smaller units in the gut before absorptions, which may induce metabolic acidosis

Question 6

Phosphate Functions

Answer 6

• Buffer
• Increase water binding
• Adjust pH
• Anti-caking agent
• Form ionic “bridges”
• Interact with proteins, other charged hydrocolloids

Question 7

Most common foods that contain phosphate;

Answer 7

• Carbonated
• Beverages
• Cereal products
• Dairy products
• Egg products
• Fruits and vegetables
• Gums and gels
• Meat products

Question 8

Phosphates in carbonated beverages

Answer 8

1) Mineral supplementation in some carbonated and non carbonated beverages
• Iron and calcium phosphates – most common in non carbonated beverages

2) Complex metal ions
• Prevent loss of carbonation caused by heavy metals (25-90% less CO2 needed in untreated water

3) Acidification
• Common in cola beverages

4) Improve flow of powders in dry mixes
• Tricalcium phosphate (TCP) most common in use and also assists in size distribution of the dry mix

Question 9

Purpose of Food Processing (Toxin Removal)

Answer 9

Remove organs that contain toxin – e.g: tetradotoxin.

Question 10

Purpose of Food Processing (Quality and Marketing)

Answer 10

Brands, consistency, user friendly

Question 11

Purpose of Food Processing (Improves food nutritional value)

Answer 11

• Enrichment
• Fortification

Question 12

Nutrient changes in food processing

Answer 12

1) Food additives
2) Salting
3) Acid and Alkali treatments
4) Refining operations – Milling
5) Heat treatment
6) Food Irradiation
7) Food Storage

Question 13

Nutrient changes in food processing (Food additives)

Answer 13

1) Sodium bisulphite & Sulphur dioxide
• Degradation of food color
• Breakdown of thiamine (particularly at neutral pH)
• Cleave folic acid
• Scavenge O2 – protect ascorbic acid

Question 14

Nutrient changes in food processing (Salting)

Answer 14

• Some proteins are denatured

• Digestibility of fish protein decrease with increasing salt concentration, but EAA do not appear to be affected.

• Vitamins and minerals lost during salting, but such losses not to be great.

Question 15

Nutrient changes in food processing (Acid and Alkali treatments)

Answer 15

1) Treatment with acid (Below pH 4)
• Vitamin A will be converted to the less active cis
form and B12 are inactivated in dilute acid solution.
• Break down of folic acid, panthotenic acid.

2) Treatment with alkali
• Decrease the level of thiamine
• Significant loss of tryptophan, threonine, histidine, and arginine.
• Loss of vitamin C.

Question 16

Nutrient changes in food processing (Refining operations – Milling)

Answer 16

• Outer layers of vegetables contain more nutrients

• Grinding, cutting, mincing, etc.

• Does not only involve a reduction of particle size, but also a decrease of protein, fiber, vitamins, minerals.

• Fortification and enrichment of nutrients are recommended.

Question 17

Nutrient changes in food processing (Heat treatment)

Answer 17

• Boiling, Blanching, Deep frying, Baking etc.
• Cellulose is little affected (fiber decrease)
• Protein changes or denature
• Losses of vitamin C (blanching)

Question 18

Nutrient changes in food processing (Food Irradiation)

Answer 18

• Process of exposing food to ionizing radiation to destroy microorganisms or insects that might be present in the foods.

• Sprout inhibition, delay of ripening, increase of juice yield, and improvement of re-hydration.

• Thiamine and vitamin C are most sensitive to food irradiation, riboflavin, and niacin are reduce.

Question 19

Nutrient changes in food processing (Food Storage)

Answer 19

• Refrigeration

• Removing of heat – cooling, freezing

• In meat, oxidative rancidity may also occur during cold storage

• Protein may also undergo decomposition

• Water soluble vitamins decrease (vitamin B and C)

Question 20

Food Processing Toxicants

Answer 20

• Chemicals added or created during food processing can be anti nutrient, toxicants, or pro-toxicants.

• Anti nutrients chemicals or processes will block, interfere, or destroy nutrients availability.

• Toxic chemicals or toxicants formed from food processing will be dose dependent and subject to biotransformation, sequestration, and elimination.

Question 21

Toxicants formed during food processing

Answer 21

• Amino Acid Pyrolysates (Heterocyclic Aromatic Amines)

• Maillard reaction products

• Food Irradiations – unique radiolytic products (URPs)

• Lipid oxidation products

• Lysinoalanine cross linkage from alkali/heat treatment of proteins

• Acrylamide formation in foods prepared at high temperature

Question 22

N-nitrosamine formation from nitrites

Answer 22

• Nitrite used in curing meat and fish products.

• Has antimicrobial activity, sensory, and reacts with
myoglobin and hemoglobin to form red nitrosyl
compounds (NO3 is converted to NO2 to give red
color).

• Nitrite reacts with 2, 3 amines to form stable
nitrosamine.

• High temperature processing and protein
degradation to 2, 3 amines increase rate of
formation.

• Conversion of nitrite to nitrosamine is block by
ascorbic acid.

• Carcinogenic, mutagenic.

Question 23

Polycyclic Aromatic Hydrocarbons (PAHs)

Answer 23

• Formed in the high temperature pyrolisis of CHO in grilling and smoking meats.

• PAHs most likely to pose health problems are:
a) Benzo-α-pyrene
b) 3,4-Benzepyrene (BP)
c) 7,12-dimethylbenzanthrene (DMBA)

Question 24

Long-term effects of PAHs:

Answer 24

• Cataracts
• Kidney and liver damage
• Jaundice
• Skin problems
• Allergies
• Carcinogenic, mutagenic.

Question 25

Heterocyclic Aromatic Amines (HCAs)

Answer 25

• Heterocyclic Aromatic Amines (HCAs) formed during grilling of meat, fish, or other high protein rich foods.

• Produce by food pyrolisis products derived from
tryptophan, glutamic acid, phenylalanine, and lysine.

• High temperature thermal degradation products of tryptophan and other amino acids.

• Mutagenic (form DNA and protein adduct).

• Compounds rapidly absorbed by the GIT, distributed to all organs and tissues.

• The major target organs are liver, small and large
intestine, oral cavity, lung, blood vessels, skin, and
mammary gland.

Question 26

Mechanism of Acrylamide Formation

Answer 26

• Acrylamide derived from asparagine (amino acid) in the presence of sugar.

• Carbonyl or C=O (glucose) facilitates reaction
(Maillard-type).

• High asparagine, sugar, and temp = high acrylamide.

Question 27

Acrylamide Uses

Answer 27

• Cement binder
• Plastic manufacture
• Waste water treatment (flocculent)
• Soil conditioner (prevents erosion)
• Thickening agent for pesticides
• Refining sugar (flocculent)
• Cosmetics
• Ore processing
• Laboratory gels (PAGE)
• Polyacrylamide in food packaging

Question 28

Estimated Exposure of Acrylamide from Food

Answer 28

• Calculated acrylamide intake.

• FAO/WHO: 0.3 - 0.8 μg/kg body weight/day.

• FDA: 0.37 μg/kg body weight per day (mean).

• Common average used is 1 μg/kg bw/da.

• Foods with lower levels but high consumptions
contribute significantly to estimated intake.

Question 29

Methods to Minimize Acrylamide in Food

Answer 29

• Do not over-cook high carbohydrate foods.

• Avoid foods high in asparagine and sugar.

• Decrease asparagine levels in foods via genetic
manipulation.

• Hydrolyze asparagine with acid or amidases.

• Acetylate asparagine to prevent formation of glycoside intermediates with sugar.

• Research conditions that limit acrylamide formation.