Nutritional Changes and Toxicants Formed During Food Processing Flashcards
Food Processing Approach
• Thermal processing
• Blanching and pasteurization
• Sterilization
• Refrigerated storage
• Freezing and frozen food storage
• Dehydration
• Physical processes (Milling, extrusion etc.)
• Irradiation
Factors that deteriorate foods
• Nutrients in foods
• Microbial
• Environmental exposure
Purpose of Food Processing
- Preservation
- Increase Palatability
- Toxin Removal
- Quality and Marketing
- Improves food nutritional value
Purpose of Food Processing (Preservation)
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.
Purpose of Food Processing (Increase Palatability)
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
Phosphate Functions
• Buffer
• Increase water binding
• Adjust pH
• Anti-caking agent
• Form ionic “bridges”
• Interact with proteins, other charged hydrocolloids
Most common foods that contain phosphate;
• Carbonated
• Beverages
• Cereal products
• Dairy products
• Egg products
• Fruits and vegetables
• Gums and gels
• Meat products
Phosphates in carbonated beverages
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
Purpose of Food Processing (Toxin Removal)
Remove organs that contain toxin – e.g: tetradotoxin.
Purpose of Food Processing (Quality and Marketing)
Brands, consistency, user friendly
Purpose of Food Processing (Improves food nutritional value)
• Enrichment
• Fortification
Nutrient changes in food processing
1) Food additives
2) Salting
3) Acid and Alkali treatments
4) Refining operations – Milling
5) Heat treatment
6) Food Irradiation
7) Food Storage
Nutrient changes in food processing (Food additives)
1) Sodium bisulphite & Sulphur dioxide
• Degradation of food color
• Breakdown of thiamine (particularly at neutral pH)
• Cleave folic acid
• Scavenge O2 – protect ascorbic acid
Nutrient changes in food processing (Salting)
• 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.
Nutrient changes in food processing (Acid and Alkali treatments)
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.
Nutrient changes in food processing (Refining operations – Milling)
• 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.
Nutrient changes in food processing (Heat treatment)
• Boiling, Blanching, Deep frying, Baking etc.
• Cellulose is little affected (fiber decrease)
• Protein changes or denature
• Losses of vitamin C (blanching)
Nutrient changes in food processing (Food Irradiation)
• 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.
Nutrient changes in food processing (Food Storage)
• 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)
Food Processing Toxicants
• 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.
Toxicants formed during food processing
• 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
N-nitrosamine formation from nitrites
• 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.
Polycyclic Aromatic Hydrocarbons (PAHs)
• 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)
Long-term effects of PAHs:
• Cataracts
• Kidney and liver damage
• Jaundice
• Skin problems
• Allergies
• Carcinogenic, mutagenic.
Heterocyclic Aromatic Amines (HCAs)
• 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.
Mechanism of Acrylamide Formation
• 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.
Acrylamide Uses
• 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
Estimated Exposure of Acrylamide from Food
• 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.
Methods to Minimize Acrylamide in Food
• 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.
