Acrylamide: Mechanism of Formation in Heated Foods

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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
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ACRYLAMIDE SHOCK Press Release April 24, 2002
Stockholm University/Swedish NFA revealed
acrylamide presence in variety of cooked foods.

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Sample Survey Results
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What is Acrylamide?
high boiling point
very hydrophilic water loving
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Initial Thoughts on the Mechanism of Acrylamide
Formation
Acrylamide
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Effectiveness of Amino Acids and Dextrose to Form
Acrylamide

• Acrylamide Formation
• Potato starch lt50 ppb
• Potato starch dextrose lt50 ppb
• Potato starch asparagine 117 ppb
• Potato starch dextrose asparagine 9270 ppb

• Other Amino Acids
• Alanine lt50 ppb Arginine lt50 ppb
• Aspartic A. lt50 ppb Cysteine lt50 ppb
• Lysine lt50 ppb Methionine lt50 ppb
• Threonine lt50 ppb Valine lt50 ppb
• Glutamine 156 ppb Asparagine 9270 ppb

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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.
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Free vs. Bound 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
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Dose/Response Dextrose
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Other Carbonyl Sources Which Produce Acrylamide
Also ribose
All of these carbonyl sources produce significant
acrylamide in the model system with asparagine.
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Use of Isotopes to Understand the Mechanism of
Acrylamide Formation from the Reaction of
Asparagine and Dextrose


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Label Expt 1 Amide15N-Labeled Asparagine
m/z 73
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Label Expt 2 Amine 15N-Labeled Asparagine
m/z 72
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Label Expt 3 Uniformly Labeled Asparagine
m/z 76
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Acrylamide Formation Mechanism
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Monitoring Intermediates in Acrylamide Formation
A
B
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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.

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Asparaginase Mode of Action
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Asparaginase Experiment on Potato Product
Washed Russet Burbank Potatoes
Boil for 1 hour
Blend flesh 13 with distilled water
Asparaginase-treated
Control
45 min _at_ RT
Microwave _at_ 2 min intervals for total of 10
min. Highly Cooked to Maximize Acrylamide
Formation (both control and asparaginase-treate
d products were dry and brown)
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Asparagine Analysis of Enzyme-Treated Potato
Product
Control
Asparatic acid
Asparagine
Unreacted FMOC
ISTD
Asparaginase treated
Asparagine
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Asparaginase Reduces Acrylamide in Cooked Potato
Products
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Acrylamide Precursors Where to Intervene

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

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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.