Formation, Occurrence and Strategies to Address Acrylamide

in Food

Robert Brown, Ph.D.

Possible mechanism for formation of acrylamide from asparagine

C – CH2 – CH

NH2

COOHO

H2N

HOOH

OH

OH

OH

O

+

C – CH2 – CH

N

COOHO

H2N

Possible mechanism for formation of acrylamide from asparagine

Maillard ProductsC – CH2 – CH

N

COOHO

H2N

C – CH = CH2

O

H2N

C – CH2 – CH2

N

O

H2N- CO2

Beta-elimination

EA ~70 kcal/mole

EA~25 - 50 kcal/mole

Insights

1. The chemical pathway leading to AA is a low yield pathway with high activation energy.

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

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

Insights

1. The chemical pathway leading to AA is a low yield pathway with high activation energy.

2. The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.

Remove Reactants

Disrupt Reaction

Remove Acrylamide

after formation

Toxicology

Dealing With The Acrylamide Issue

Remove Reactants

Disrupt Reaction

Remove Acrylamide

after formation

Toxicology

Dealing With The Acrylamide Issue

Summary table of results - CSL

1200012800Over cooked

35003500Cooked

100200

Frozen frying chips

as 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.

0.0

0

10000

20000

AA (ppb)

0.0 0.1 0.2 0.3 0.4ASN0.0 0.1 0.20.2

20000

30000

0.2

0.50.0

0.80.6

GLU0.40.2

1.00.8

GLU

Surface Plot of AA/Substrate Relationship

R-Squared = .97

AA = -245.2 - 427.9*(ASN) + 460.1*(GLU) + 60582.7*(ASN)*(GLU)

Insights

1. The chemical pathway leading to AA is a low yield pathway with high activation energy.

2. The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.

3. The chemical reaction of asparagine and glucose is second order when the substrates are approximately equal. When one is substantially lower it becomes rate-limiting.

Remove Reactants

Disrupt Reaction

Remove Acrylamide

after formation

Toxicology

Dealing With The Acrylamide Issue

Summary table of results - CSL

1200012800Over cooked

35003500Cooked

100200

Frozen frying chips

as sold

35002800Chipped & fried

Nd<10boiled

<30Nd<10

King 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))

Insights

1. The chemical pathway leading to AA is a low yield pathway with high activation energy.

2. The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.

3. The chemical reaction of asparagine and glucose is second order when the substrates are approximately equal. When one is substantially lower it becomes rate-limiting.

4. AA formation is temperature critical and occurs well below temps at which food is commonly cooked. It will probably not be possible to cook food without forming at least some AA.

Effect of pH on Acrylamide Formation

0

5000

10000

15000

20000

25000

30000

4 5 6 7 8 9

pH

AA

(p

pb

)

120 C, 40 min150 C, 15 min

Prevent Asparagine and Glucose Reaction

Watchout: The inhibitor(s) must be food safe.

The Idea

Raw Reaction Cooking ReducedFood Inhibitor Acrylamide

+ +

glucose I1 I2melanoidins (colour)

flavourvola tiles

k1 k2 k3

k4,k5,....acrylamidekm,kn,...

Kinetic model (Wedzicha & Mottram)

Rate constants

Allow the rate of each step to be quantifiedin terms of reaction variables: pH, T, concentration

of glucose and amino acid

Remove Reactants

Disrupt Reaction

Remove Acrylamide

after formation

Toxicology

Dealing With The Acrylamide Issue

Remove After Formation

• Supercritical CO2 – removes everything but destroys the product

• UV light – no effect, several wavelengths including visible

Remove Reactants

Disrupt Reaction

Remove Acrylamide

after formation

Toxicology

Dealing With The Acrylamide Issue

0

5

10

15

20

25

30

ug/day

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

0

5

10

15

20

25

30

ug/day

All Other Foods

Breads

CerealBiscuit / Cookies

Relative Exposure – All Potato Products Zero

Coffee Cakes Dried Foods Pop Corn Salty Snacks Chocolate Products Nuts/Seeds/Butters

Food For Thought

• The notion of “carcinogens” in food is not new (cooked meat, NAS report, “Ames/Gold” list).

• Humans have eaten these foods for millennia.

• There are no obvious “quick fixes” or magic bullets. Much of what we have learned looks interesting, but the solution has not been found.

Feasibility Analysis

• Removal of substrates must take into account kinetics of formation along with importance of other constituents.

• Low temperature intervention will require development of new cooking methods. Some foods will be impossible to cook at low temperature.

• No universal “magic bullets” have been found. Addition of substances may work for some products but with variable efficacy. There is no precedent for an intervention into the food supply on this scale

Final Thoughts • The issue affects a large portion of the food supply.

Lowering acrylamide in one or a few foods has no effect- everything must be changed.

• Food cooked at home and in restaurants is a big challenge, and a significant source of acrylamide exposure.

• What does victory look like? Given the magnitude of change to the food supply we need to fully understand two things:

1. the nature of the low dose hazard to humans, and

2. the impact of any proposed interventions. Are there any unintended consequences to public health?