Transcript Technologické procesy a výživa

The sources of toxic compounds in
our food?
Man-made (anthropogenic)
Natural origin
Food additives
Toxins of vegetable origin
Food contaminants
Toxins in mushrooms
- inorganic
Mycotoxins
- organic
Microbial toxins
Component produced during Toxins of animal origin
the technological and
cooking procedures
Products of interactions in
human body
Chemical changes during food processing
•
•
•
•
•
Agriculture
Food industry
Catering
Cooking in households
Other techniques in households
Mycotoxins – toxic products of
moulds
Humidity, warmth, damage of corns due to
crop techniques
• Harvesting of cereals
• Storage of cereals
• Storage and package of cereal products
(bread packed in PE)
• Fruits, compote, beer (malt)
• Nuts, peanuts, coffee, cocoa
• Mouldy fodder (animal)
• Metabolites of mycotoxins in milk
Toxic effects of mycotoxins
Genotoxic and carcinogenic:
aflatoxins, ochratoxins, fumonisins, griseofulvin, trichotecens
Hepatotoxic:
aflatoxins, luteoscyrin, sterigmatocystin
Estrogenic: zearalenon
Nefrotoxic: ochratoxin, citrinin
Dermatotoxic: trichotecens, psoralens, sporidesmins, verrukarins
Hematotoxic: aflatoxins, ochratoxin A, trichotecens, zearalenon
Immunotoxic: aflatoxins, ochratoxin A, trichotecens, patulin,
sporidesmin
Diseases associated with mycotoxins
Aflatoxins
Aflatoxicosis, kwashiorkor, Reyes syndrom,
primary hepatocarcinoma (synergism with
HBvirus)
Ochratoxin A
Balkan endemic nefropathy, kidney tumors
Trichotecens
Alimentar toxic aleukia, stachybotriotoxicosis
Fumonisins
Oesophageal tumors
Citreoviridin
Citrinin,
Luteoscyrin
Acute cardiac beri-beri, yellow rice disease
Ergot alcaloids
ergotism
(Toxic products of
Claviceps purpurea)
Aflatoxin B1
Primary hepatocarcinoma – metabolic activation
Prevention of mycotoxins
Proper handling food commodities prone to
contamination with fungies
Not eat mouldy food
Not used the mouldy food as fodder for domestic
animals
Proper control of food products (mostly nuts),
especially before Christmas
Toxic products of bacteria
Biogenic amines
Histidine in fish meat – bacterial decarboxylases histamine
Tyrosine in cheese - bacterial decarboxylases – tyramine
(increase of blood pressure in case of combination with
MAO inhibitors)
Bacterial toxicoinfection a toxicoses: staphyfylococcus
enterotoxicosis, botulotoxin , intoxication with Clostridium.
perfringens A, Bacillus cereus
Bacterial reduction of nitrates to nitrites:
methemoglobinemia, nitrosamines
Lipolytic and proteolytic effects of microorganisms
Nitrosamines
Nitrates
Bacterial
reductases
Vit. C, E
Nitrites
+ acidic pH
(+ amines)
Nitrosamines
Methemoglobinaemia
of infants
Smoked meat: mixture of
nitrate and nitrite salts
Uncommon toxicants originated due to foodprocessing technology
Chlorpropandiols (3-MCPD)
Production of soup spice, soy sauce, products containing
protein hydrolysates
Acid digestion (HCl) – cleavage of fatty acids – binding of
chlorine = increased biologic activity of chlorine derivatives
(mutagenicity). Enzymatic hydrolysis is more expensive but
safe
Acrylamide
Formation during the production of chips, bread, cakes etc.
The amount depends somehow on the technology used
Potential carcinogen (Hb adducts), neurological changes
Acrylamide
Product of Maillard reaction
The Maillard reaction is a form of nonenzymatic
browning. It results from a chemical reaction
between an amino acid and a reducing sugar,
usually requiring heat. It can be formed in starchy
foods during cooking.
Formation during the production of chips, bread,
cakes etc. The amount depends somehow on the
technology used
• Potential carcinogen (Hb adducts), neurological
changes
Culinary technologies
Frying :
Changes in frying oil = changes in frying foods
Chemical reaction during frying:
1. Hydrolysis due to water vapour released from frying
food. Acrolein, originated in final phase, is irritating
agents for eyes and mucous tissues.
2. Oxidative reactions – especially in longer used oils, where
the presence of polar compounds facilitates foaming.
3. Formation of hydroperoxides – oxidation of mono-ene and
saturated fatty acids
4. Cumulating of polymers in frying oil
Adverse consequences of frying:
Increased oxidation stress
(carcinogenicity, degenerative diseases, premature aging)
Loss of unsaturated FA
Oxidation of blood lipids, namely LDL cholesterol,
Oxidative products cumulated in macrophages constitute a basis
of atherosclerotic plate in walls of blood vessels.
Lipid peroxidation generates a complex variety of products; some
of them react with proteins and DNA (damage of DNA,
genotoxicity, carcinogenicity
Chemoprevention by means of antioxidants in fruits, vegetables,
green tea etc.
Adverse consequences of frying:
Increased intake of fat (increased risk of cancer)
Food with a high content of water (e.g. potatoes, mushrooms,
vegetables) absorbs a lot of fat during the frying process,
because the water in poruses is evaporating and the free places
are filled with fat.
Adverse consequences of frying:
High temperature decomposes ascorbic acid, vitamin E,
carotenes and other vitamins (loss of vitamins)
Also the content of some minerals and trace elements (e.g.
selenium) can change
Non-enzymatic browning of amino acids with reducing sugars
or with oxidative products in frying oil. Nitrogen products are
generating such as pyrrols, pyrrazines, furans (Maillard
reaction). Disbalance of amino acids and a worsening of
protein quality
Loss of unsaturated FA (PUFA)
Production of polycyclic aromatic hydrocarbons
Production of heterocyclic amines
Heterocyclic amines (HA, protein pyrolysates)
Generated in the meat dishes during the cooking process due to
reaction of amino acids (e.g. glycin, phenylalanine), creatine,
creatinine, and sugar (glucose) in meat in high temperature.
The amount of HA depends on the height of temperature and
the duration of cooking procedure
Hamburger, beef, fish, bouillon
Heterocyclic amines (cont.)
More than 20 HAs have been isolated from cooked food
Extremely potent indirect-acting mutagens in short-term tests
on mutagenicity (induction of mutation of bacterial tester
strains, DNA adducts formation, chromosomal changes)
HAs are activated by means of CYP1A2 (cytochrome P450)
Detoxification: hydroxylation, conjugation
Some of HA are carcinogenic for animals, but HAs are not
strong carcinogens
Possibly carcinogenic for humans – association with Ca colon
and rectum
Factors affecting the yield of HAs in cooked food:
Cooking temperature (more above 200°C) – well done
grilled, pan-fried or barbecue red meat
Cooking time (transport of HAs from the meat to the pan
residue)
Cooking method (no HAs in microwave warming)
Type of food (content of precursors and inhibitors)
Heterocyclic amines (prevention)
Use cooking, stewing, prevent meat from open fire, use
microwave, remove roasted part of meat
Reduce the resorption of HA in organism (crude fibres,
vegetable, chlorophyll)
Blockade of metabolic activation to carcinogenic
intermediates (catechines in green tea, onion, cruciferous
vegetable, allylsulfids in garlic, carotenoids
Some heterocyclic amines are also present in cigarette
smoke!!!
Heterocyclic amines (prevention)
Universal recommendation
The formation of HAs is minimized if the cooking
temperature is kept low and constants (below 200°C)
Consume the meat always with a lot of vegetables and fruit
Drink a glass of (red) wine to the meal
Polycyclic aromatic hydrocarbons (PAHs)
Production: incomplete combustion of organic compounds
(including foods such as smoked products, grilled, fried, baked
meat, barbecue etc.)
The use of open fire contribute mostly to the generation of PAHs
in food.
Food containing PAHs are especially:
Fried, roasted, grilled meat and smoked sausage
Smoked meat and fish
Fried chips
Roasted coffee
sedimentation of air particles containing PAH on leafy vegetables
Cooling and freezing of food
Reason:
To avoid of the loss of vitamins and other micronutrients
The importance of refrigerators in prevention of stomach cancer
Shocked freezing (during the slow freezing the small ice crystal in
meat destroy the cells and let the fluids escape – loss of vitamins and
minerals
Cooling of poultry with running water increases the risk of
contamination with Campylobacter jejuni.
Notice: moulds can grow even in the temperature slightly above
zero, i.e. in refrigerator
Drying
Increases the level of heavy metals contaminated vegetable,
herbs, herb-teas etc. (Cd, Pb)
Insufficient termal procedures
Increased risk of infectious:
Bacterial (salmoneloses)
Intoxication (botulotoxin, staphyllococci enterotoxicosis)
Viruses (Hepatitis A)
Parazites (taeniae, trichinellosis)
Trans fatty acids
Unsaturated fatty acids with at least one double bond in a
trans configuration in the molecule
Intake: ruminant meat, fat, milk fat, butter
Hardened fats are the main exposure source (hydrogenation
of vegetable oil to hardened fat – margarine- products)
One of risk factors of the ischemic heart disease
TFA increase the plasma ratio of total to HDL cholesterol
Estimated about 7% of coronary artery disease to be
attributable to TFA
GMO and food production
Improvement of agronomic charactristics
Tolerance to herbicides:
- Induction of gene coding the enzyme for resistance to
herbicides (e.g. Tolerance to glyphosphate – Roundup Ready
or to glucosinate - BASTA).
- Induction of gene coding the enzyme detoxifying herbicide
Pros.: increase of production, decrease of costs
Contr: lowering of biodiversity, creation of „superweeds“?
Resistence to insects
- Endotoxin from B. thuringiensis (Bt-maize, cotton-plant)
Advantage: reduction of amount of chemical pesticides,
lowering of mycotoxins, protection of beneficial insect
GMO and food production (cont.)
• Resistance to viruses, bacteria and
fungies
• Increased tolerance to abiotic
stress
(dryness, salinity)
• Increase of iron bioavailability
GMO and food production
Improvement of nutritional characteristics
Modification of fatty acids, optimalization of lipid spectrum in edible
oils,
Improvement of quality of protein in food and feeds (increased
amounts of essential aminoacids, e.g. methionine in soya),
Improvement of biosynthesis of starch,
Biosynthesis of -carotene (Golden rice) – prevention of vitamin A
deficiency in Southwest Asia,
Synthesis of -tocoferol (-tocoferol metyltransferase from
Arabidopsis),
Increased amount of iron in rice (gene for ferritin from Phaseolus
vulg., or for termoresistent fytase from Aspergillus fumigatus or
increased expression of protein metalothionein)
GMO and food production
• Improvement of sensoric characteristics and
storability:
FLAVR SAVR TM tomatoes with prolonged time of
ripening – inhibition of polygalakturase, key
enzyme for softening of cell walls.
• Changes of technology:
Production of chymosine by means of GM
microorganisms (earlier from calf stomach)
GMO and food production
• Production of farmaceuticals (vaccines, insulin);
• Introduction od vaccines into the ordinary used
food (e.g. vaccine against HBV or diarrhea
diseases into bananas or potatoes; not yet
realized
GMO and commerce
• Prolongation of lifetime of cut flowers;
• Changes of color (production of blue cotton),
wood lignin (furniture industry);
Further potential GMO utilisation
• Production of human proteins (factors
VIII and IX for the therapy of hemofilia,
alfa-1-antitrypsin for the therapy of
emphyseme, antitrombin for prevention of
trombosis)
• Increased growth of domestic animals
(livestock) (e.g. transport of gene for
growth factor to salmon)
• Increased resistance to animal diseases
(leucosis in poultry, BSE,, skrapie in sheep,
H5N1 in poultry)
Potential health and environmental
risks of GMO?
• Resistance to ATB
• Toxicity
• Alergenicity
• Worsening of biodiversity
• Cross-pollination between GMO and non-GMO plants
• Polyresistance to herbicides
• Contamination of honey with pollen from GMO
plants (not known adverse effect yet)
• Other???????
Prevention: legislation, health risk assessment
Message to take with
• Efficient prevention of moulds
• Use of moderate cooking temperature
• Limit the use of grilling, BBQ and other techniques
using high temperatute and open fire
• Limit the consumption of cakes containing
margarines with high concentration of trans fatty
acids