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 (bpetersen@exponent.com)