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Acrylamide: Mechanism of Formation in Heated Foods. David Zyzak, Ph.D. Procter & Gamble Snacks and Beverage Analytical and Microbiology Cincinnati, Ohio. ACRYLAMIDE SHOCK Press Release April 24, 2002.

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acrylamide mechanism of formation in heated foods
Acrylamide: Mechanism of Formation in Heated Foods

David Zyzak, Ph.D.

Procter & Gamble

Snacks and Beverage Analytical and Microbiology

Cincinnati, Ohio

acrylamide shock press release april 24 2002
ACRYLAMIDE SHOCK Press Release April 24, 2002

Stockholm University/Swedish NFA revealed acrylamide presence in variety of cooked foods.

slide3

Food Product

Acrylamide (ppb)

Toasted English Muffin, 5 min

50

Tortilla Chips

97

Baby Food Potatoes

101

Banana Chips

125

Roasted Asparagus

143

Pretzels

196

Hearty Rye Crispbread

242

Baked Potato Chips

317

Corn Chips

331

Cooked Taco Shell

559

Blue Potato Chips

736

Kettle Potato Chips

3400

Sample Survey Results

what is acrylamide

Acrylamide

What is Acrylamide?

• high boiling point

• very hydrophilic – water loving

slide5

Initial Thoughts on the Mechanism of

Acrylamide Formation

Acrolein

Acrylic Acid

X

X

carbonyl

Asparagine

Acrylamide

slide6

Effectiveness of Amino Acids and Dextrose to Form Acrylamide

Model System

Amino acid

Reducing sugar

Variety of ingredients

fry

+

Measure Acrylamide

Potato Starch + Water

  • Acrylamide Formation
        • Potato starch <50 ppb
        • Potato starch + dextrose <50 ppb
        • Potato starch + asparagine 117 ppb
        • Potato starch + dextrose + asparagine 9270 ppb
  • 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 ppbAsparagine 9270 ppb
slide7

Amino Acid Composition in Potatoes

Approximately 50% of amino acids are in the free state

(not incorporated into protein).

Asparagine is roughly half of the free amino acid content.

slide8

Free vs. Bound Asparagine

+ dextrose

Acrylamide?

N-acetyl asparagine

Asparagine occurring as component of protein does not have an accessible primary amine group for Schiff base formation, and would not be expected to participate in the production of acrylamide. Blocking the amine group in asparagine, N-acetyl asparagine, is an effective analogue to test.

Result: No acrylamide formation observed

slide9

Dose/Response: Dextrose

Asparagine at 1.25%

slide10

GLYOXAL

GLYCERALDEHYDE

2-DEOXYGLUCOSE

Other Carbonyl Sources Which Produce Acrylamide

Also: ribose

All of these carbonyl sources produce significant acrylamide in the model system with asparagine.

slide11

Acrylamide

carbonyl

Asparagine

Use of Isotopes to Understand the Mechanism of Acrylamide Formation from the Reaction of Asparagine and Dextrose

slide12

Label Expt #1: Amide15N-Labeled Asparagine

Mono-labeled Acrylamide

+ dextrose

m/z 73

97+ % of Total Acrylamide Response

m/z 72 Unlabeled Acrylamide

m/z 73

slide13

Label Expt #2: Amine 15N-Labeled Asparagine

m/z 73

+ dextrose

Unlabeled Acrylamide

m/z 72

m/z 72

slide14

Label Expt #3: Uniformly Labeled Asparagine

Tetra-labeled Acrylamide

m/z 76

+ dextrose

m/z 75

m/z 74

m/z 73

m/z 72

m/z 76

slide17

Understanding Acrylamide Formation in Food Products

  • Is asparagine the only precursor to acrylamide in heated foods?
  • What about other potential sources of acrylamide?
  • methionine, glutamine, cysteine, acrolein, etc…
  • Selective removal of asparagine with asparaginase to address these questions.
slide19

Asparaginase Experiment on Potato Product

Washed Russet Burbank Potatoes

Boil for 1 hour

Blend flesh 1:3 with distilled water

Asparaginase-treated

Control

45 min @ RT

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)

slide20

Asparagine Analysis of Enzyme-Treated

Potato Product

Control

Asparatic acid

Asparagine

Unreacted

FMOC

ISTD

Asparaginase treated

Asparagine

slide21

Asparaginase Reduces Acrylamide in Cooked Potato Products

Potato Product

Microwaved snack

Acrylamide (ppb)

Control Asparaginase

20,500 164

% Reduction1

>99

1Calculated as (control – asparaginase treated)/control x 100.

slide22

Acrylamide Precursors – Where to Intervene

Asparagine

Reducing Sugars

- Glucose

- Fructose

- Sucrose hydrolysis?

  • Factors affecting asparagine and reducing sugars
  • - Variety of potato
  • - Storage conditions
conclusions
Conclusions
  • 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.