Acrylamide: Formation, Exposure, Possible Reduction
Strategies
by Barbara PetersenExponent, Inc.
Materials and conclusions have been drawn from the October 2002 JIFSAN workshop, the FAO/WHO report on acrylamide, and presentations at the US FDA Food Advisory Committee meetings (Dec 2002, Feb 2003)
Workshop: Acrylamide in Food: Scientific uncertainties, issues and research strategies
(Oct 2002)
Funded: Participants fees from government, industry and academia
5 working groups considered current knowledge, identified gaps and recommended future research needs
Acrylamide (AA) in Food: Scientific uncertainties, issues and Research
strategies: Working Groups
Mechanisms of formation Analytical methodology Exposure and biomarkers Toxicology and metabolic consequences Risk communication
Research priorities
Research priorities are summarized along with the meeting working papers on
– http://www.jifsan.umd.edu
Exposure to Acrylamide: Preliminary estimates
Exposure to Acrylamide (AA)– Preliminary estimates available from
international sources including FAO/WHO using different models and different study types
Sweden:40 µg/person/day (0.67 µg/kgbw-day, 60 kg bw/person)
FAO/WHO – June 2002Assumptions: Swedish residue data and food
consumption data from U.S., the Netherlands, Norway, Australia, Sweden, and from IARC EPIC Study
Probabilistic Modeling as well as Point Estimate Methods
Long-Term Exposure Estimates0.3 - 0.8 µg/kgbw-day
Initial international estimates of mean exposure
Swiss duplicate diet study
.28 mcg/kg bw/day (vs WHO .3-.8 mcg/kg BW/day) – Breakfast 8%– Lunch 21%– Dinner 22%– Snacks 13%– Coffee 36%
US FDA conducted multiple analyses
Several different surveys for food consumption including data from the USDA’s Continuing survey of food intake conducted in 1994-96, 98
Acrylamide levels from FDA testing plus evaluation of the impact on intake if levels change in foods
Different models including Monte Carlo modeling to incorporate more realistic estimates of the probability of occurrence of residues
Category European Data FDA DataBreads 12-3200 <10-364Crispbread <30-1670Crackers and Biscuits <30-2000 26-504Cereal <30-2300 52-266Other Grains <30Potato Chips 150-1280 117-2762Other Salty Snacks 122-416 12-1168French Fries 85-1104 20-1325Other Potato Products <20-12400Other Vegetable and Fruit Products 10-<50 <10-70Prepared Foods <30-30Meats <30-64 <10-116Candy and Dessert items <20-110 <10-909Cookies 36-199Coffee and Tea 170-700 175-351Other Nonalcoholic Beverages <30Alcoholic Beverages 30Dairy Products 10-100 <10-43Baby Food and Formula 40-120 <10-130Dry Soup Mixes <10-1184Gravy and Seasonings 38-54Miscellaneous 70-200 <10-125
Summary of Acrylamide Values in Food (ppb)
Summary of Acrylamide Values in Food
Factors applied to food Acrylamide concentration
Ground Coffee/24 = Coffee as Consumed
(Experimentally Derived) Instant Coffee Crystals/60 = Instant Coffee
as Consumed (3g Coffee/6oz Cup) Dry Soup Mix/12 = Soup as Consumed
(15g Soup Mix/6 oz Cup) Dry Cocoa Powder/10 = Cocoa as
Consumed (17g Cocoa Powder/6oz Cup)
US FDA estimates of intake
Acrylamide Intake of Population (ages 2 and older)
Mean intake =0.37 µg/kg body weight/day
Acrylamide Intake DistributionCSFII 1994-96, 1998; 2+ Population
00 1 2 3
00 1 2 3
Acrylamide Intake (µg/kgbw-d)
Mean = 0.37 µg/kgbw-d
90th Percentile = 0.81 µg/kgbw-d
Contribution by food category (for FDA-Tested Foods)
Food MeanPopulationAAIntake
(µg/kg bw day)
Cumulativepercentile
French fries(RF)
0.056 15
French fries(OB
0.049 27
Brewed coffee 0.047 39Breakfast
cereal0.044 51
Potato chips 0.041 61Cookies 0.040 72
Toast 0.023 78Soft bread 0.020 83
Food MeanPopulationAA Intake
(µg/kg bw day)
Cumulativepercentile
Corn snacks 0.011 86Crackers 0.008 88Pretzels 0.008 90Popcorn 0.006 92
Baked beans 0.006 93Breade
chicken0.005 94
Peanut butter 0.004 96Soup mix 0.003 96
Contribution by food category (for FDA-Tested Foods (continued)
Food MeanPopulationAA Intake(µg/kg bw day)
Cumulativepercentile
Cocoa 0.002 97Crisp
bread/Matzo0.002 97
Instant coffee 0.002 98Bagels 0.002 98
Chocolate 0.002 98Tortilla 0.002 99
Breaded fish 0.001 100
Food MeanPopulationAA Intake(µg/kg bw day)
Cumulative
percentile
Doughnuts
0.001 100
Almonds 0.000 100Nuts &seeds
0.000 100
Taro 0.000 100Soy
protein0.000 100
Pork rinds 0.000 100Malteddrinks
0.000 100
Total 0.37
What-If Scenarios
Effect of Mitigation Measure on Population Mean Acrylamide Intake
Set Acrylamide Levels in Chosen Foods to 0 µg/kg
Rerun the Model
What-If Scenarios CSFII, 1994-96, 98, 2+ Population
Population Mean=0.37 µg/kgbw-d Remove Acrylamide from French Fries
– Mean – 0.26 µg/kgbw-d Remove Acrylamide from Snack Foods
– Mean – 0.31 µg/kgbw-d Remove Acrylamide from Breakfast Cereal
– Mean – 0.33 µg/kgbw-d Remove Acrylamide from Coffee
– Mean – 0.34 µg/kgbw-d
Calories and nutrient intake
Foods tested and found to contain acrylamide (so far) constitute:• 38% of calories• 33% of carbohydrates• 36% of fiber• 28% of fat• 20% of calcium• 47% of iron• 25 to 35% of other micronutrients• 15% of vitamin A• 34% of vitamin E• 22 to 44% of B, C and folate vitamins
Summary of FDA intake assessments
Mean Population Acrylamide Intakes Consistent with Previous Exposure Estimates
Greatest Contributors to Mean Population Acrylamide Intake are the Same for all tested scenarios
Some Foods with Lower Levels Contribute Appreciably to the Overall Mean Population Intake because they are Commonly Consumed
No One Food Accounts for the Majority of the Mean Population Intake-
Significant potential for disrupting nutritional quality of the diet
CH2
CH
C
NH2
O
Acrylamide
CH COOHNH2
CH2
C
NH2
O
Asparagine
carbonyl
CH2
CH
C
OH
O
Acrylic Acid
NH3
X X
CH2
CH
C
H
O
Acrolein
NH3
Mechanisms of Acrylamide formation that have been studied
CH COOHNH2
CH2
CH2
C
NH2
O
Glutamine
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
Dose/Response: DextroseDose/Response: DextroseAcrylamide Formation: Dextrose Kinetics
Dextrose [%]
0.0 0.5 1.0 1.5 2.0 2.5
Acry
lam
ide
[p
pm
]
0.0
0.5
1.0
1.5
2.0
2.5
Asparagine is 10 g in the model system
Acrylamide = k [Dextrose]0.99
r2 = 0.99
Asparagine at 1.25%
Conclusions from initial research reports
Asparagine is the major source of acrylamide formation in foods.
Carbonyl source (reducing sugars) is required in the reaction.
Oil oxidation products and starch do not appear to be significant factors in acrylamide formation.
Impact of Potato variety on AALevels (from D. Mottram, U. Reading)
1200012800Over cooked
35003500Cooked
100200Frozen frying chipsas sold
35002800Chipped & fried
Nd<10boiled
<30Nd<10King Edward potatoes raw
350310Chipped & fried
nd<10Boiled
<30
LC-MS-MS
nd
GC-MS
<10Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Acrylamide formation influenced by starting raw material
Asparagine in various crops
Cheese 40 – 300 Asparagus 5.4 – 108Cocoa (raw) 30.9 - roasted @ 125C 14.5 - roasted @ 135C 9.4Potato 0.5 – 10 mg/g Rye 0.2 – 2.8Wheat 0.02 – 2 Corn 0.6 – 1Also in peanuts, soybeans, onions, coffee, tomatoes, fruits, etc.From Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.
Impact of browning on AA levels (from D. Mottram, U. Reading)
1200012800Over cooked
35003500Cooked
100200Frozen frying chipsas sold
35002800Chipped & fried
Nd<10boiled
<30Nd<10King Edward potatoes raw
350310Chipped & fried
nd<10Boiled
<30
LC-MS-MS
nd
GC-MS
<10Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Yield of acrylamide increases substantially
with browning
Effect of temperature on AA formation
0
2000
4000
6000
8000
10000
12000
110 130 150
Temperature (C)
Acrylamide (ppb)
1% gluc, 0.2% asn in sodium phosphate at pH 7.0 for 15 minutes.
380 400 420 440
Temperature (Kelvin)
05
00
01
00
00
15
00
02
00
00
Acr
yla
mid
e (
pp
b)
AA Formation at 15 Minutes as a function of Temperature
AA = 442.3 * e(.07930*(Temp-383))
Effect of pH on Acrylamide formation
0
5000
10000
15000
20000
25000
30000
4 5 6 7 8 9
pH
AA
(pp
b)
120 C, 40 min150 C, 15 min
Prevent asparagine and glucose reaction
Watchout: The inhibitor(s) must be food safe for long term (daily) intake from multiple food sources and should not impact nutritional status.
The Idea
Raw Reaction Cooking ReducedFood Inhibitor Acrylamide
+ +
Acrylamide Precursors – Where to Intervene
Reducing levels of precursors:– Asparagine– Reducing sugars
– For example: by selecting different varieties of foods or by different storage or processing procedures
Potato Product
Microwaved snack
Acrylamide (ppb)Control Asparaginase
20,500 164
% Reduction1
>99
1Calculated as (control – asparaginase treated)/control x 100.
Asparaginase reduces Acrylamide in Cooked Potato Products
Asparaginase Experiment on Potato Product
Boil for 1 hour
Blend flesh 1:3 with distilled water
Asparaginase-treated
Microwave @ 2 min intervals for total of 10 min.Highly Cooked to Maximize Acrylamide Formation (both control and asparaginase-treated products were dry and brown)
Control45 min @ RT
Washed Russet Burbank Potatoes
Impact of treating with Asparaginase
By treating with asparaginase there was a 99% reduction in the levels of acrylamide in the potato mixture following the use of the microwave
Remove after formation – overview of some preliminary research
Supercritical CO2 – removes everything but destroys the product
UV light – no effect at several wavelengths including
visible
Insight and recommendations for Next Steps
The concerted research and actions by government, industry and academia have resulted in rapid progress towards understanding the mechanisms of formation in food
The notion of “carcinogens” in food is not new (cooked meat, US National Academy of Sciences Report1), research by Lois Gold & Bruce Ames and in numerous research articles
Humans have eaten these foods for millennia
1National Research Council, 1996. Carcinogens and Anticarcinogens in the Human Diet, ‘A comparison of naturally occurring and synthetic substance. National Academy Press.
Feasibility of reducing levels
Removal of substrates must take into account kinetics of formation along with importance of other constituents
Preparing foods by cooking at such low temperatures willl require development of new cooking methods. Some foods will be impossible to prepare without temperatures that are high enough to form acrylamide.
Addition of substances may work for some products but its too early to evaluate efficacy; could cause major changes in the foods
There is no precedent for an intervention into the food supply on this scale; potential to alter nutritional and/or safety aspects of food
Concluding remarks
The issue affects a large portion of the food supply. Lowering acrylamide in one or a few foods has little effect on long term intakes - many foods would need to be altered.
Food cooked at home and in restaurants represent significant source of acrylamide exposure and would be less amenable to intervention strategies.
Concluding remarks (continued)
Before any interventions are proposed, we need to fully understand two things:
– the nature of the low dose hazard to humans, and
– the impact of any proposed interventions. Are there any unintended consequences to public health?
Additional information
Copies of the presentation and or the original references/presentations can be provided on request
to Barbara Petersen ([email protected])
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