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Oleh: Aisha, STP., MSc.
Toxicant from food
processing
Maillard reaction product
Polycyclic aromatic
amineN-
nitrosaminesPolycyclic aromatic
hydrocarbons
Benzo[a]pyrene
Acrylamide
Source : Charred or smoked meat and fish Cereals Flour Vegetables Fruits Water, soil, dust Cigarette smoke Vegetables oil
-
the largest class of chemical compounds, containing two or more fused aromatic rings made up of carbon and hydrogen atoms. PAHs are formed in incomplete combustion processes which
occur whenever wood, coal or oil are burnt.
Result of the environmental pollution but also as a consequence of some thermal treatments
Food processing (smoking, drying, roasting, baking or frying) produces PAHs in certain levels
Formed mainly from carbohydrates cooked at hight temp in the absence of oxygen.
Broiling meat in hot ceramic or charcoal briquettes the melted fat will come into contact with very hot surface.
PAHs then produced in the ensuing reactions, PAHs rise with resulting cooking fumes and are deposited on the meat.
Polycyclic aromatic hydrocarbon (PAH) that is a byproduct of incomplete combustion or burning of organic (carbon-containing) items
The most commonly known carcinogenic PAH.
Heating starch at :370-390 0C =0.7 ppb650 0C =17 ppb
Many cooking processes: 370—390 0C The surface temperature of baking bread
may approach 400 0C and deep fat frying is 400 - 600 0C,
10 mg of BaP 3x a week: skin tumors 100 mg of BaP in 10 weeks : stomach cancers
Benzo[a]pyrene is not mutagenic and carcinogenic by itself, but must be first converted to active metabolites.
Metabolic conversion:- A cytochrome’ P450-mediated oxidation produce a 7,8-epoxide. - The 7,8- epoxide undergoes an epoxide hydrolase-mediated hydration,
produce the 7,8-diol- 7,8-diol further oxidized by cytochrome P450, produces diolepoxide.- Diolepoxide: highly mutagenic without metabolic activation and is also
highly carcinogenic at the site of administration. - The benzo[a]pyrene diolepoxide can react with various components in
the cells, including DNA
Case History: Benzopyrene from meat on a barbecue
Natural molecules can become
dangerous during food
preparation!
Modern method:- Indirect smoking (using external smoke generator).- Used in modern industrialized kilns- Operated automatically under carefully controlled conditions- Smoke can be washed from particles before coming into contact with the food.
Conventional method:- Direct smoking (smoke
developed in the smoking chamber, traditionally in smokehouses)
PAHs Ham Cooked cured loin Medium ground sausages
External part
Internal part
External part Internal part
External part
Internal part
Cyclopenta[c,d]pyrene 1.62 0.53 0.07 n.d 11.39 7.07
Benzo[a]anthracene 8.88 0.41 6.48 0.38 8.78 1.29
Chrysene 6.29 0.56 4.46 0.48 6.63 0.55
5-metylchrysene 1.72 0.28 2.73 0.30 2.06 0.36
Benzo[j]fluoroanthene 0.31 n.d 0.31 n.d 1.2 n.d
Benzo[a]pyrene 0.37 0.28 0.30 0.28 0.89 0.32
Mean content of 15 PAHs in meat products industrially smoked, μg/kg
Ciecierska, Marta. 2007. INFLUENCE OF SMOKING PROCESS ON POLYCYCLIC AROMATIC HYDROCARBONS’ CONTENT
IN MEAT PRODUCTS* . Acta Sci. Pol., Technol. Aliment. 6(4) 2007, 17-28
PAHs Ham Cooked cured loin Medium ground sausages
External part
Internal part
External part Internal part
External part
Internal part
Cyclopenta[c,d]pyrene 3.26 0.49 1.27 n.d 12.17 7.78
Benzo[a]anthracene 6.74 0.40 9.25 0.22 5.86 1.51
Chrysene 6.20 0.68 9.12 0.42 5.07 0.57
5-metylchrysene 1.28 0.28 2.98 0.31 1.39 0.38
Benzo[j]fluoroanthene 0.59 n.d 0.43 n.d 0.83 n.d
Benzo[a]pyrene 0.43 0.27 0.37 0.29 0.40 0.31
Mean content of 15 PAHs in meat products traditionally smoked, μg/kg
Ciecierska, Marta. 2007. INFLUENCE OF SMOKING PROCESS ON POLYCYCLIC AROMATIC HYDROCARBONS’ CONTENT
IN MEAT PRODUCTS* . Acta Sci. Pol., Technol. Aliment. 6(4) 2007, 17-28
1. Traditional method of smoking affected the higher contamination PAHs than industrial proceess.
2. Industrial smoking process influenced higher PAHs content only in case of exteriors of medium-ground sausages.
3. For all products smoked using both methods, interiors had a significantly lower PAHs contamination than exteriors of the same products.
4. Benzo[a]pyrene’s content was much lower than maximum tolerable
limit of 5 μg·kg-1, which was set for smoked meat products in Commission Regulation (EC) No. 208/2005. Therefore industrial and even traditional smoking of meat is a safe process.
Ciecierska, Marta. 2007. INFLUENCE OF SMOKING PROCESS ON POLYCYCLIC AROMATIC HYDROCARBONS’ CONTENT
IN MEAT PRODUCTS* . Acta Sci. Pol., Technol. Aliment. 6(4) 2007, 17-28
1912, L. C. Maillard hypothesized reaction of brown pigments and polymers produced from the reaction of amino group of amino acid and carbonyl group of sugar.
Nonenzymatic browning reaction: Reaction of amines and carbonyl under heat
treatment in vivo and biological systems damage
Reaction products: brown color, characteristic roasted or smoky odors, pro- and antioxidants, mutagens, carcinogens.
Occurs between reducing sugars and amines at high temperatures
Produces flavor-aroma
Produces color
Produces antioxidant products
Produces toxic products
Destroys nutrients (lysine)
AmineAmmonia
Phospholipids
Amino acids
Proteins
Carbonyl
Aldehydes
Ketones
Reducing sugars
Polysaccharides
Oxidised lipids
Amino Carbonyl
Interaction
(Amadori product)
HEAT
MelanoidinsBrown colour
Volatile compounds
CarbonylsEsters
Amide (acrylamide)Heterocyclic compounds
Source: produced during the cooking of protein-rich food; beef, chicken, broiled seafood, hamburger,
Mutagens , esp on the surface layers where most pyrolysates are found.
PAA
Imidazoquinoline(IQ)-type
Heating a mixture of creatine/creatinine, amino acids, and sugar
Non-IQ typePyrolysis products formed from
tryptophan
Cyclization of creatinine to form the imidazole moiety due to heat treatment
Revertants of TA98
Food 2500C 3000C 4000C
Beef 178 11400
Chicken 661 15120
Egg 121 4750
Hairtail 849 12320
Eel 309 6540
Squid, dried 269 8000 4490
Skipjack tuna, dried 1,220 24300 6200
Seaweed, nori 260 3040
Abbreviation Z R1 R2 R3
IQ C H H H
MeIQ C Me H H
MeIQx N H H Me
4,8-DiMeIQx N Me H Me
The IQ-Type
The non-IQ-Type
Trp-P-1 and Trp-P-2 are toxic to animals LD50 of Trp-P-1: 200 mg/kg in mice, 380 mg/kg in hamsters, 100 mg/kg in
rats. Over LD50 died in 1h. IQ and MeIQX in Beef extracts metabolically converted to active
mutagens by liver tissue through N-oxidation and O-acetylation produce highly reactive metabolites that for, DNA adducts
Food with Trp-P-1 or Trp-P-2 tumor and hepatoma in mice Highly potent mutagens and carcinogens
PAA Found in Revertants /µg
MeIQ Broiled sardine 661,000
IQ Fried beef 433,000
MeIQx Fried beef 1435,000
Trp-P-1 Broiled sardine 104,000
Glu-P-1 Glutamic acid pyrolysates 49,000
Trp-P-1 Broiled sardine, broiled beef 39,000
Glu-P-2 Broiled, dried cuttlefish 1,900
Aflatoxin B1 Corn 6,000
Benzo[a]pyrene Broiled beef 320
Formed from the interaction of nitrite and secondary, tertiary amines. Found in wide variety of foods A significant source of nitrite: cured meat Nitrite ions in curing meat: antimicrobial (inhibit the growth of C. botulinum,
produces appealing red color to meats from nitrosomyoglobin and nitrosylhemoglobin pigments, gives a desirable cured flavor to meat products
Permissible levels of nitrite in cured foods :vary, 10 to 200 ppm nitrite in humans : from reduction of dietary nitrate to nitrite by bacteria in
the mouth and in the intestinal tract. Nitrate in the relatively in high levels (1000—3000 ppm (cabbage,
cauliflower, carrots, celery, and spinach)
pH dependent (3.4) Weakly basic amines are more rapid Several anions, such as halogens and thiocyanate, promote the nitrosation
process High temperature food heating , i.e bacon Diethylnitrosamine (DEN) and dimethylnitrosamine (DMN) occur in the
gastric juice of experimental animals and humans fed diets containing amines and nitrite
Heating of nitrite-treated foods produce nitrosamines. Cured meats have all been shown to contain nitrosamines, the higher levels
appearing in cured meats that have been subjected to relatively high heating.
In Norway in 1962, epidemic of food poisoning in sheep, extremely high levels of nitrosamines were detected in herring meal treated with nitrite as a preservative. The sheep suffered severe liver disease and many of them died.
formation of nitrosamine in nitrite-treated fish: dependent on the temperature of preparation following the addition of nitrite.
Refrigerated fish treated with nitrite had no more nitrosamine than fresh fish treated with nitrite,
heat treatment of fish increased the rate of nitrosamine formation following
addition of nitrite due to increased concentrations of secondary amines resulting from protein degradation during the heating process.
meat Nitrosamines Level (ppb)
Smoked sausages DimethylnitrosaminesDiethylnitrosamines
<6<6
frankfuters Dimethylnitrosamines 11-84
salami Dimethylnitrosamines 1-4
Fried bacon DimethylnitrosaminesNitrosoproline
1-401-40
Over 100 food substances assayed, approximately 80% were shown to be carcinogenic in at least one animal species.
Dimethyl- and diethylnitrosamine are two of the most potent carcinogens Administration of dimethylnitrosamine at 50 ppm in the diet produces
malignant liver tumors in rats in 26—40 weeks. Higher doses produce kidney tumors.
As the dose of diethylnitrosamine is reduced below 0.5 mg/kg,. No clear threshold dose for carcinogenicity of nitrosamines in the diet has yet been established.
Addition of reducing agent (erythsorbate
or ascorbate) to the curing mix to reduce
or eliminate nitrosamine formation
Reduce food processing temperature
Minimize cured meat consumption
First report, Sweden, April 2002
Found in a wide range of foods, including dietary staples
• Potato products
• Breakfast cereal
• Coffee
• Bakery products
• Snack foods
Food Amount
(ppb)
Baby food 17-130
French fries 70-1036
Potato chips 117-2764
Cereals 47-266
Bread and
bakery
10-354
Snack foods 111-1168
coffe 275-351
Chocolate
products
45-909
Formed from asparagine and glucose via Maillardreaction.
Acrylamide Formation (heating at 1800C, 30 min)
▪ Asparagine 0.99 µg/g
▪ Asparagine + glucose 1200 µg/g
▪ Asparagine + Potato starch + glucose 9270 µg/g
Asparagine and carbonyl compound (glucose, glyceraldehide) play an important role in acrylamide formation in cooked foods.
Effectiveness of Amino Acids and
Dextrose to Form Acrylamide
Acrylamide Formation– Potato starch <50 ppb
– Potato starch + dextrose <50 ppb
– Potato starch + asparagine 117 ppb
– Potato starch + dextrose + asparagine 9270 ppb
Potato Starch + Water
Amino acid
Reducing sugar
Variety of ingredients+
fry
Measure Acrylamide
Model System
Other Amino Acids–Alanine <50 ppb Arginine <50 ppb
–Aspartic A. <50 ppb Cysteine <50 ppb
–Lysine <50 ppb Methionine <50 ppb
–Threonine <50 ppb Valine <50 ppb
–Glutamine 156 ppb Asparagine 9270 ppb
Amino Acid Composition in Potatoes
Approximately 50% of amino acids are in the free state
(not incorporated into protein).
Asparagine is roughly half of the free amino acid content.
CH COOHNH2
CH2
C
NH2
O
Amide
moiety
H2OCO2
AsparagineCarbonyl
(glucose)Schiff’s
base Acrylamide
Lipid Glycerol
3H2
O
2H2
O
Acrolein
(O)
Acrylamid
e
.NH
2From amino
acid
NH3From amino
acid
Acrylic
acid
Radical
Ingestion of heat-treated starch-rich foods
(potato chips and french fries)
Acute toxicity :LD50 in rats: 159 mg/kg -
300 mg/kg body weight
Classified by the US EPA ( as a B2
(probable human carcinogen)
IARC (international Agency
for research on cancer) as a 2B (possible
human carcinogen)
ACGIH (American
Conference of Industrial Hygiene) as A3
Acrylamide - toxicology
Proven neurotoxic compound in animals and in humans
Effects range from drowsiness to incoordination, hallucinations, confusion, abnormal sensation, muscle weakness, incoordination
Genotoxic compound with the potential to affect the germinal cells thus leading to hereditary changes
Causing cancer in laboratory animals (rats)
Studies in humans (e.g. 8000 workers in China) which were positive on neurotoxicity failed to prove relationship with cancer in humans (too small numbers ?)
POTATO PRODUCTS Acrylamide levels
increased with degree of browning
Brown color as measured by “L” and “a” values correlated highly with acrylamide levels
Same acrylamide levels found in French fries with similar degree of browning (fried French fries)
45 µg/kg 76 µg/kg 262 µg/kg
516 µg/kg 866 µg/kg 1512 µg/kg
R2 = 0.8551
10
100
1000
10000
45 55 65 75
"L" value
mic
rog
ram
s a
cry
lam
ide/k
g
Fre
nch
fri
es
R2 = 0.8558
10
100
1000
10000
5 10 15 20
"a" value
mic
rog
ram
s a
cry
lam
ide
/kg
Fre
nc
h f
rie
s
Food should not be cooked excessively (for too long or at too high temp) Maintain cooking at temp under 1500C, no preferable flavor chemicals FDA: Eat a balanced diet, choose a variety of foods that are low fat and rich
in high-fiber grains, fruits, and veggies