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