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

2. Possible mechanism for formation of acrylamide from asparagineOH OH
C – CH2 – CH
NH2
COOH O
H2N HO + O OH OH
C – CH2 – CH N
COOH O
H2N
By now we all know that this is the reaction we are dealing with. Although it has been suggested that other pathways are theoretically possible, no data to support this.
It seems likely that this reaction is a part of, or off-shoot of the Maillard reaction.
This is a proposed reaction pathway from Mottram.

3. Possible mechanism for formation of acrylamide from asparagine
C – CH2 – CH N
COOH O
H2N
Maillard Products
EA~ kcal/mole
- CO2
C – CH = CH2 O
H2N
C – CH2 – CH2 N O
H2N
Beta-elimination
By now we all know that this is the reaction we are dealing with. Although it has been suggested that other pathways are theoretically possible, no data to support this.
It seems likely that this reaction is a part of, or off-shoot of the Maillard reaction.
This is a proposed reaction pathway from Mottram.
EA ~70 kcal/mole

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

5. Summary of Acrylamide Values in Food
Realize that this slide is difficult to read, but all data are publicly available on various websites. Want to make the points that:
Widespread across many different food types – clearly not a “potato issue”
Measured amounts vary greatly within and across food categories
This is only what we know so far- as additional foods are examined the list will surely grow longer.
Any interventions we can contemplate to address this question will have widespread effects.

6. 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

7. Insights
The chemical pathway leading to AA is a low yield pathway with high activation energy.
The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.

8. Dealing With The Acrylamide Issue
Remove Acrylamide after formation
Remove Reactants
Disrupt Reaction
Like many people my initial reaction to the story out of Sweden was that it must be a mistake.
As events unfolded last summer and it became clear that the results were real, F-L formed a project team of some of our best scientists and engineers to look into this question.
Fairly quickly our thinking coalesced into 4 distinct boxes, and we divided our team up to work in each of these areas.
We could try to get rid of the substrates for the reaction.
We could possibly do something to disrupt the reaction and prevent AA from forming. This was the successful approach used to deal with nitrosamines in meat (ascorbate).
AA is supposedly reactive, so could we do something to get rid of it after it was formed.
Finally, under Toxicology we could have titled this box “What does it all mean?” This may be the most important box because it is the perceived hazard that drives this issue, not the mere fact that it is present in food.
Toxicology

9. Dealing With The Acrylamide Issue
Remove Acrylamide after formation
Remove Reactants
Disrupt Reaction
Toxicology

10. Summary table of results - CSL
12000
12800
Over cooked
3500
Cooked
100
200
Frozen frying chips
as sold
2800
Chipped & fried Nd
<10
boiled
<30
King Edward potatoes raw
350
310 nd
Boiled
LC-MS-MS
GC-MS
Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Acrylamide formation influenced by starting raw material
This slide was kindly supplied by Don Mottram, and shows some data from the UK.
The finding that two different varieties of potato, prepared similarly, have vastly different AA levels is an important clue to what may be going on, and leads to some potential intervention strategies.
Clearly the starting material has some impact.

11. Asparagine in Various Crops
Cheese – 300
Asparagus – 108
Cocoa (raw)
- 125C
- 135C
Potato – 10 mg/g
Rye – 2.8
Wheat – 2
Corn – 1
Also in peanuts, soybeans, onions, coffee, tomatoes, fruits, etc.
From Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.
Wide range of results within and across crops.
Not understood at this time how much is genetic variation vs. effects of storage conditions.

12. Surface Plot of AA/Substrate Relationship
0.0
10000
20000
AA (ppb)
0.1
0.2
0.3
0.4
ASN
20000
30000
0.2
0.5
0.0
0.2
0.8
0.6
GLU
0.4
0.2
1.0
AA = *(ASN) *(GLU) *(ASN)*(GLU)
R-Squared = .97

13. Insights
The chemical pathway leading to AA is a low yield pathway with high activation energy.
The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.
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.

14. Dealing With The Acrylamide Issue
Remove Acrylamide after formation
Remove Reactants
Disrupt Reaction
Toxicology

15. Summary table of results - CSL
12000
12800
Over cooked
3500
Cooked
100
200
Frozen frying chips
as sold
2800
Chipped & fried Nd
<10
boiled
<30
King Edward potatoes raw
350
310 nd
Boiled
LC-MS-MS
GC-MS
Baking potatoes raw
SNFA result (µg/kg)
Acrylamide concentration (µg/kg)
Sample
Yield of acrylamide increases substantially with browning

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

17. AA Formation at 15 Minutes as a function of Temperature
380
400
420
440
Temperature (Kelvin)
5000
10000
15000
20000
Acrylamide (ppb)
AA Formation at 15 Minutes as a function of Temperature
AA = * e
(.07930*(Temp-383))

18. Insights
The chemical pathway leading to AA is a low yield pathway with high activation energy.
The AA question affects a large fraction of the food supply, calories and nutrients commonly consumed.
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.
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.

19. Effect of pH on Acrylamide Formation

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

21. Kinetic model (Wedzicha & Mottram)g l u c o s e I 1 2 m a n i d ( r ) f v t k 3 4 , 5 . y
Rate constants
Allow the rate of each step to be quantified
in terms of reaction variables: pH, T, concentration
of glucose and amino acid

22. Dealing With The Acrylamide Issue
Remove Acrylamide after formation
Remove Reactants
Disrupt Reaction
We have investigated a couple of possibilities here but have no success.
Supercritical CO2 extraction removes aa but destroys the product.
Have looked at light energy of various wavelengths, the theory being that we could force aa to react in situ. Although an interesting idea, nothing has worked in either the test-tube or in products.
Toxicology

23. Remove After Formation
Supercritical CO2
removes everything but destroys the product
UV light
no effect, several wavelengths including visible

24. Dealing With The Acrylamide Issue
Remove Acrylamide after formation
Remove Reactants
Disrupt Reaction
Toxicology

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

26. Relative Exposure – All Potato Products Zero
Coffee
Cakes Dried Foods Pop Corn
Salty Snacks
Chocolate Products Nuts/Seeds/Butters
Breads
Cereal
Biscuit / Cookies
All Other Foods

27. 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.

28. 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

29. 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:
the nature of the low dose hazard to humans, and
the impact of any proposed interventions. Are there any unintended consequences to public health?