Transcript
ED73.9002: Processing Effects on the functional
components of food
Acrylamide: Thermal Process induced Toxicant
By-Yakindra Prasad Timilsena
(111332)Jyotsna Shrestha Khanal
(111328)1
• Introduction • Mechanisms of formation• Toxicology• Amounts in different food sources• Regulations & allowable limits• Methods of Determination• Preventive measures• Conclusion
Presentation Outline
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Less tasty side to these culinary delights:
Thermally induced harmful chemicals (Carcinogens)
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• Synthesized for the first time in 1949• Unsaturated & highly reactive
amide• White odorless crystalline solid, soluble in
water, ethanol, ether, and chloroform
• Formation: baking, roasting, toasting, grilling, frying
• Common foods: French fries, potato chips,bread, biscuits, coffee, roasted
cereals
What is Acrylamide ?
S.N. Properties Values1. IUPAC name Prop-2 enamide2. Molecular formula C3H5NO
3. MW 71.08 g mol−1
4. Density 1.13 g/cm3
5. Melting point 84.5 °C6. Solubility in water 2.04 kg/L (at 25 °C)7. Color white crystalline solid8. Boiling point 136 °C
Properties of Acryl amide
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• 1950s: Synthetic Polyacrylamide-based flocculants
• 1960s: Synthetic coagulants in mineral processing industries
• 2002: Swedish researchers announced the discovery of acrylamide in food
Acrylamide in industrial use
6PAM
Cereals, potato & coffee : variety and growing factors
Cereals : reducing sugars are abundant → conc. Of Asparagine →AAPotato : asparagine is abundant →conc. of reducing sugar→ AA
Acrylamide production in foods
Concentrations & availability of Precursor molecules
AA Formed by Maillard reaction
between asparagine and reducing sugars
(precursors)
Factors (temp., heat intensity, water activity) in processing technologies
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Impact of Potato variety on AA Levels (Source: D. Mottram, U. Reading)
1200012800Over cooked35003500Cooked100200
Frozen frying chips
as sold
35002800Chipped & friedNd<10boiled
<30Nd<10
King Edward potatoes raw
350310Chipped & friedNd<10Boiled
<30
LC-MS-MS
Nd
GC-MS
<10
Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Acrylamide formation influenced by starting raw material
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Acryl amide
formation
Heat
Carbonyl source
L-Asparaginesource
• Removing or changing one of the parameter prevents formation.
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Mechanism for formation
C – CH2 – CH
NH2
COOHO
H2N
HOOH
OH
OH
OH
O
+
C – CH2 – CH
N
COOHO
H2N
Asparagine Glucose
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From Asparagine and Reducing sugar
Maillard reactionProducts
C – CH2 – CH
N
COOHO
H2N
C – CH = CH2
O
H2N
C – CH2 – CH2
N
O
H2N
- CO2
Acrylamide11
Mechanism for formation
From Asparagine and Reducing sugar
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Acrylic acidAcrolein
Mechanism for formation
From Triglycerides
Triglycerides
Heat, O2
Acrylamide
NH3
Variation in concentration of Acrylamide with temperature and time
168 170 172 174 176 178 180 182 184 1860
200
400
600
800
1000
1200
1400
2.5 min3.5 min
Temperature (0C)
Acr
ylam
ide
(ppm
)
Source: Gertz and Klosterman (2002) Eur. J. Lipid Sci. Technol. 104:762-771. 13
380 400 420 440
Temperature (Kelvin)
050
0010
000
1500
020
000
Acr
ylam
ide
(ppb
)
AA Formation as a function of Temperature
AA = 442.3 * e(0.07930*(Temp-383))
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Potato chipsFrying time: 15 minutes
Effect of pH on Acrylamide Formation
4 5 6 7 8 90
5000
10000
15000
20000
25000
30000
120 C, 40 min
150 C, 15 min
pH
AA
(pp
b)
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Effect of browning in AA formation (Source: D. Mottram, U. Reading)
1200012800Over cooked35003500Cooked100200
Frozen frying chips
as sold
35002800Chipped & friedNd<10boiled
<30Nd<10
King Edward potatoes raw
350310Chipped & friednd<10Boiled
<30
LC-MS-MS
nd
GC-MS
<10
Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Yield of acrylamide increases
substantially with browning
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Amount of Acrylamide in Foods (ppm)
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Category European Data FDA Data
Breads 12-3200 <10-364
Crispbread <30-1670
Crackers and Biscuits <30-2000 26-504
Cereal <30-2300 52-266
Other Grains <30
Potato Chips 150-1280 117-2762
Other Salty Snacks 122-416 12-1168
French Fries 85-1104 20-1325
Other Potato Products <20-12400Other Veg and Fruit Products 10-<50 <10-70
Amount of Acrylamide in Foods (ppm)
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Category European Data FDA Data
Meats < 30-64 < 10-116
Candy and Dessert items < 20-110 < 10-909
Cookies 36-199
Coffee and Tea 170-700 175-351
Other Nonalcoholic Beverages < 30
Alcoholic Beverages 30
Dairy Products 10-100 < 10-43
Baby Food and Formula 40-120 < 10-130
Dry Soup Mixes < 10-1184
Gravy and Seasonings 38-54
Amino Acids Level of Acrylamide Formation
Alanine <50 ppb
Asparagine 9270 ppb
Aspartic Acid <50 ppb
Cysteine <50 ppb
Glutamine 156 ppb
Lysine <50 ppb
Methionine <50 ppb
Threonine <50 ppb
Asparagine !!!
Source : Barbara Petersen, Exponent, Inc. October 2002 JIFSAN workshop19
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Food product Interval (month)
Acrylamide level (µg/kg)
Initial Second
Breakfast cereal 12 238 238
Soluble coffee powder 12 771 256
Roasted barley 9 265 225
Roasted coffee 7 203 147
Dried chicory 5 214 174
Roasted chicory 5 4015 3395
Cocoa 3 180 177
Chocolate with almond 2 94 73
Soluble chocolate powder 1 54 41
Stability of acrylamide in various foodstuffs
Adapted from Delatour et al.
Asparagine in Various Crops
• Cheese 40 – 300 mg/100gm• Asparagus 5.4 – 108 mg/100gm• Cocoa (raw) 30.9 mg/100gm - roasted @ 1250C 14.5 mg/100gm
- roasted @ 1350C 9.4 mg/100gm• Potato 500 – 1000 mg/100gm• Rye 0.2 – 2.8 mg/100gm• Wheat 0.2 – 20 mg/100gm• Corn 0.6 – 1 mg/100gm
Source: Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.21
• Known neurotoxicant (IARC 2002; Manson et al. 2005)
– Peripheral neuropathy– Tingling/numbness of extremities– Loss of reflexes– Chronic CNS dysfunction and neuropathy
• Reproductive toxicity• Animal carcinogen (CNS, endocrine organs)• EPA has classified acrylamide as a B2 carcinogen
(probable human carcinogen) (IRIS2009).• Biomarker – adducts on amino acid valine of Hb.
Toxicology
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• 2 micrograms per kg body weight per day
(Office of Environmental Health Hazard Assessment)
• Exposure at a level 1,000 times greater than the MADL is expected to have no observable effect
• No Observed Adverse Effect Level (NOAEL) of 15 mg/kg bw/day were identified in mice
• Legislation under formulation
Maximum allowable dose level (MADL
• Water extraction • Analysis by GC-MS with or w/o bromination
• by LC-MS/MS • by LC-MS or -UV after deriv. with
mercaptobenzoic acid • GC-Ion Trap MS
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Acryl amide extracted with water, test portion homogenized, acidified to pH 4-5
Addition of Carrez I and Carrez II solution
Extraction with Ethylacetate hexane (80:20), Filtration over Na2SO4
Clean up with Flourisil elution of acrylamide with acetone
Evaporation, residue taken up in ethylacetate, triethylamine added
Filtration, injection into GC-MS
GC-MS method
Acrylamide Precursors – Where to Intervene
Asparagine Reducing Sugars- Glucose- Fructose- Sucrose hydrolysis?
• Factors affecting asparagine and reducing sugars- Variety of potato- Storage conditions
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Acrylamide Possible Mitigation Strategies
1. Reduction or removal of sugars. Selection of low sugar cultivar. Blanching and soaking to leach out sugars.
2. Reduction or removal of asparagines. Use of enzymes to degrade asparagine during food
processing. Blanching to leach out asparagine
3. Processing Conditions Altering time-temperature of processing. Altering heat processing methods Changing pH of food by using acids Use of antioxidants
Reduction of Acrylamide formation in Potatoes products
• Improve agronomic practices• Select potatoes variety with less asparagine• Store potatoes tubers >10°C• Blanching (82°C)• Add antioxidants• Dip slices in citric acid (0.75%) solution• Dip in NaCl, CaCl2 solution
• Use of enzyme- asparaginase• Addition of amino acids glycine.
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Reduction of Acrylamide in cereal products
• Adjustment of time and temperature during baking.
• Extend fermentation times where feasible.• Substitution of ammonium bicarbonate with
alternatives• Avoid or minimize use of reducing sugars• Avoidance of very high baking temperature• Use of asparaginase in dough to degrade
asparagine.29
Enzyme mechanism
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Impact of treating with Asparaginase
• By treating with asparaginase there was a 99% reduction in the levels of acrylamide in the potato mixture
• Product characteristics fully preserved• No change in process parameters• Commercially viable and available ???
µg/day0
5
10
15
20
25
30
Biscuit / Cookies
All Other Foods
Relative Exposure to Acrylamide in U.S. Food
French Fries & Potatoes
Breads
Potato ChipsCereal
Coffee Cakes Dried Foods Pop Corn Salty Snacks Chocolate Products Nuts/Seeds/Butters
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Conclusion
• Acrylamide formation in thermally processed foods is a major challenges for bakery, French fries and chip producing industries.
• challenges still remain in terms of the needs to develop simple and rapid test methods.
• different pre-frying treatments on the reduction of acrylamide (AA) formation are under investigation 33
What about these cereal based foods ?
34Chapati Doughnut
Selroti Puri
“Foods should not be cooked excessively...for too long or at too high a temperature... However, all food…should be cooked thoroughly to destroy food borne pathogens.”
Thanks for your kind attention
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Is it possible to cook food without forming at least some AA ?????
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