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