Formation, Occurrence and Strategies to Address Acrylamide in Food Robert Brown, Ph.D.

Possible mechanism for formation of acrylamide from asparagine C – CH 2 – CH NH2NH2 COOH O H2NH2N HO OH O + C – CH 2 – CH N COOH O H2NH2N

Possible mechanism for formation of acrylamide from asparagine Maillard Products C – CH 2 – CH N COOH O H2NH2N C – CH = CH 2 O H2NH2N C – CH 2 – CH 2 N O H2NH2N - CO 2 Beta-elimination E A ~70 kcal/mole E A ~ kcal/mole

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

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 Over cooked 3500 Cooked Frozen frying chips as sold Chipped & fried Nd<10boiled <30Nd<10 King Edward potatoes raw Chipped & fried nd<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

Asparagine in Various Crops Cheese 40 – 300 Asparagus 5.4 – 108 Cocoa (raw) C C 9.4 Potato 0.5 – 10 mg/g Rye 0.2 – 2.8 Wheat0.02 – 2 Corn 0.6 – 1 Also in peanuts, soybeans, onions, coffee, tomatoes, fruits, etc. From Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.

Surface Plot of AA/Substrate Relationship R-Squared =.97 AA = *(ASN) *(GLU) *(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 Over cooked 3500 Cooked Frozen frying chips as sold Chipped & fried Nd<10boiled <30Nd<10 King Edward potatoes raw Chipped & fried nd<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

Effect of Temperature on AA Formation 1% gluc, 0.2% asn in sodium phosphate at pH 7.0 for 15 minutes.

Temperature (Kelvin) Acrylamide (ppb) AA Formation at 15 Minutes as a function of Temperature AA = * 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

Prevent Asparagine and Glucose Reaction Watchout: The inhibitor(s) must be food safe. The Idea Raw Reaction Cooking Reduced Food Inhibitor Acrylamide ++

glucose I1I2 melanoidins (colour) flavour volatiles k 1 k 2 k 3 k 4,k 5,.... acrylamide k m,k n,... Kinetic model (Wedzicha & Mottram) Rate constants Allow the rate of each step to be quantified in 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 CO 2 –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

Biscuit / Cookies All Other Foods Relative Exposure to Acrylamide in U.S. Food French Fries & Potatoes Breads Potato Chips Cereal Coffee Cakes Dried Foods Pop Corn Salty Snacks Chocolate Products Nuts/Seeds/Butters

All Other Foods Breads Cereal Biscuit / 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?