Transcript Acrylamide: Formation, exposure, possible reduction strategies

Acrylamide: Formation,
Exposure, Possible Reduction
Strategies
by Barbara Petersen
Exponent, Inc.
Materials and conclusions have been drawn from the
October 2002 JIFSAN workshop, the FAO/WHO report
on acrylamide, and presentations at the US FDA Food
Advisory Committee meetings (Dec 2002, Feb 2003)
Workshop: Acrylamide in Food: Scientific
uncertainties, issues and research strategies
(Oct 2002)
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Funded: Participants fees from
government, industry and academia
5 working groups considered current
knowledge, identified gaps and
recommended future research needs
Acrylamide (AA) in Food: Scientific
uncertainties, issues and Research
strategies: Working Groups
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Mechanisms of formation
Analytical methodology
Exposure and biomarkers
Toxicology and metabolic consequences
Risk communication
Research priorities
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Research priorities are summarized along
with the meeting working papers on
– http://www.jifsan.umd.edu
Exposure to Acrylamide:
Preliminary estimates
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Exposure to Acrylamide (AA)
– Preliminary estimates available from
international sources including FAO/WHO
using different models and different study
types
Initial international estimates of
mean exposure
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Sweden:40 µg/person/day (0.67 µg/kgbwday, 60 kg bw/person)
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FAO/WHO – June 2002
 Assumptions: Swedish residue data and food
consumption data from U.S., the Netherlands,
Norway, Australia, Sweden, and from IARC EPIC
Study
 Probabilistic Modeling as well as Point Estimate
Methods
 Long-Term Exposure Estimates
0.3 - 0.8 µg/kgbw-day
Swiss duplicate diet study
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.28 mcg/kg bw/day (vs WHO .3-.8 mcg/kg
BW/day)
–
–
–
–
–
Breakfast 8%
Lunch 21%
Dinner 22%
Snacks 13%
Coffee 36%
US FDA conducted multiple analyses
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Several different surveys for food consumption
including data from the USDA’s Continuing
survey of food intake conducted in 1994-96, 98
Acrylamide levels from FDA testing plus
evaluation of the impact on intake if levels
change in foods
Different models including Monte Carlo
modeling to incorporate more realistic estimates
of the probability of occurrence of residues
Summary of Acrylamide Values in Food
S um m a ry o f A c ryla m ide V a lue s in F o o d (ppb)
C a te g o ry
Bread s
C ris p b read
C rac kers and Bis c uits
C ereal
O ther G rains
P o tato C hip s
O ther S alty S nac ks
F renc h F ries
O ther P o tato P ro d uc ts
O ther V egetab le and F ruit P ro d uc ts
P rep ared F o o d s
M eats
C and y and D es s ert item s
C o o kies
C o ffee and T ea
O ther N o nalc o ho lic Beverages
A lc o ho lic Beverages
D airy P ro d uc ts
Bab y F o o d and F o rm ula
D ry S o up M ixes
G ravy and S eas o nings
M is c ellaneo us
E uro pe a n D a ta
12-3200
< 30-1670
< 30-2000
< 30-2300
< 30
150-1280
122-416
85-1104
< 20-12400
10-< 50
< 30-30
< 30-64
< 20-110
170-700
< 30
30
10-100
40-120
70-200
F D A D a ta
< 10-364
26-504
52-266
117-2762
12-1168
20-1325
< 10-70
< 10-116
< 10-909
36-199
175-351
< 10-43
< 10-130
< 10-1184
38-54
< 10-125
Factors applied to food Acrylamide
concentration
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Ground Coffee/24 = Coffee as Consumed
(Experimentally Derived)
Instant Coffee Crystals/60 = Instant Coffee
as Consumed (3g Coffee/6oz Cup)
Dry Soup Mix/12 = Soup as Consumed
(15g Soup Mix/6 oz Cup)
Dry Cocoa Powder/10 = Cocoa as
Consumed (17g Cocoa Powder/6oz Cup)
US FDA estimates of intake
Acrylamide Intake of Population (ages 2 and older)
Mean intake =0.37 µg/kg body weight/day
Acrylamide Intake Distribution
CSFII 1994-96, 1998; 2+ Population
Mean = 0.37 µg/kgbw-d
90th Percentile = 0.81 µg/kgbw-d
0
0
1
2
Acrylamide Intake (µg/kgbw-d)
3
Contribution by food category
(for FDA-Tested Foods)
Food
Mean
Population
AAIntake
Cumulative
percentile
Food
(µg/kg bw day)
French fries
(RF)
French fries
(OB
Brewed coffee
Breakfast
cereal
Potato chips
Cookies
Toast
Soft bread
0.056
15
0.049
27
0.047
0.044
39
51
0.041
0.040
0.023
0.020
61
72
78
83
Mean
Cumulative
Population percentile
AA Intake
(µg/kg bw day)
Corn snacks
Crackers
Pretzels
Popcorn
Baked beans
Breade
chicken
Peanut butter
Soup mix
0.011
0.008
0.008
0.006
0.006
0.005
86
88
90
92
93
94
0.004
0.003
96
96
Contribution by food category (for
FDA-Tested Foods (continued)
Food
Cumulative
percentile
Food
0.002
0.002
97
97
0.002
0.002
0.002
0.002
0.001
98
98
98
99
100
Doughnut
s
Almonds
Nuts &
seeds
Taro
Soy
protein
Pork rinds
Malted
drinks
Total
Mean
Population
AA Intake
(µg/kg bw day)
Cocoa
Crisp
bread/Matzo
Instant coffee
Bagels
Chocolate
Tortilla
Breaded fish
Cumulat
Mean
ive
Population
AA Intake percentil
(µg/kg bw day)
e
100
0.001
0.000
0.000
100
100
0.000
0.000
100
100
0.000
0.000
100
100
0.37
What-If Scenarios
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Effect of Mitigation Measure on
Population Mean Acrylamide Intake
Set Acrylamide Levels in Chosen Foods to
0 µg/kg
Rerun the Model
What-If Scenarios
CSFII, 1994-96, 98, 2+ Population
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Population Mean=0.37 µg/kgbw-d
Remove Acrylamide from French Fries
– Mean – 0.26 µg/kgbw-d
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Remove Acrylamide from Snack Foods
– Mean – 0.31 µg/kgbw-d
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Remove Acrylamide from Breakfast Cereal
– Mean – 0.33 µg/kgbw-d
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Remove Acrylamide from Coffee
– Mean – 0.34 µg/kgbw-d
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
Summary of FDA intake assessments
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Mean Population Acrylamide Intakes Consistent
with Previous Exposure Estimates
Greatest Contributors to Mean Population
Acrylamide Intake are the Same for all tested
scenarios
Some Foods with Lower Levels Contribute
Appreciably to the Overall Mean Population
Intake because they are Commonly Consumed
No One Food Accounts for the Majority of the
Mean Population IntakeSignificant potential for disrupting nutritional
quality of the diet
Mechanisms of
Acrylamide formation that have been studied
NH2
OH
C O
C O
NH3
CH
H
X
CH
X
C O
NH3
CH
CH2
CH2
CH2
Acrylamide
Acrolein
Acrylic Acid
carbonyl
NH2
NH2
C O
C O
CH2
CH2
NH2
CH COOH
Asparagine
CH2
NH2
CH COOH
Glutamine
Effectiveness of Amino Acids and
Dextrose to Form Acrylamide
Model System
+
Amino acid
Reducing sugar
Variety of ingredients
fry
Measure Acrylamide
Potato Starch + Water
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Acrylamide Formation
–
–
–
–
Potato starch
Potato starch + dextrose
Potato starch + asparagine
Potato starch + dextrose + asparagine
<50 ppb
<50 ppb
117 ppb
9270 ppb
Other Amino Acids
–Alanine
–Aspartic A.
–Lysine
–Threonine
–Glutamine
<50 ppb
<50 ppb
<50 ppb
<50 ppb
156 ppb
Arginine
Cysteine
Methionine
Valine
Asparagine
<50 ppb
<50 ppb
<50 ppb
<50 ppb
9270 ppb
Dose/Response: Dextrose
A crylam ide F orm ation: D extrose K inetics
2.5
Asparagine at 1.25%
A crylam ide [ppm ]
2.0
1.5
1.0
A crylam ide = k [D extrose] 0.99
0.5
r 2 = 0.99
0.0
0.0
0.5
1.0
D extrose [% ]
A sparagine is 10 g in the m odel system
1.5
2.0
2.5
Conclusions from initial
research reports
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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.
Impact of Potato variety on AA
Levels (from D. Mottram, U. Reading)
Sample
Baking potatoes
raw
Acrylamide
concentration (µg/kg)
GC-MS LC-MS-MS
SNFA result
(µg/kg)
<10
<30
nd
Boiled
<10
Chipped & fried
310
King Edward potatoes
raw
<10
nd
350
boiled
Chipped & fried
Frozen frying chips
as sold
<10
2800
Nd
3500
200
100
Cooked
Over cooked
3500
12800
3500
12000
Nd
Acrylamide formation
<30 by
influenced
starting raw material
Asparagine in various crops
Cheese
40 – 300
Asparagus
5.4 – 108
Cocoa (raw)
30.9
- roasted @ 125C
14.5
- roasted @ 135C
9.4
Potato
0.5 – 10 mg/g
Rye
0.2 – 2.8
Wheat
0.02 – 2
Corn
0.6 – 1
Also in peanuts, soybeans, onions, coffee, tomatoes, fruits, etc.
From Ellin Doyle, Ph.D., Food Research Inst., U. Wisc.
Impact of browning on AA levels
(from D. Mottram, U. Reading)
Sample
Acrylamide
concentration (µg/kg)
GC-MS
LC-MS-MS
SNFA result
(µg/kg)
<10
nd
<30
Boiled
Chipped & fried
King Edward potatoes
raw
<10
310
nd
350
<10
Nd
boiled
Chipped & fried
Frozen frying chips
as sold
<10
2800
Nd
3500
200
100
Cooked
Over cooked
3500
12800
3500
12000
Baking potatoes
raw
Yield of acrylamide
increases
<30substantially
with browning
Effect of temperature on AA
formation
12000
10000
8000
6000
Acrylamide (ppb)
4000
2000
0
110
130
150
Temperature (C)
1% gluc, 0.2% asn in sodium phosphate at pH 7.0 for 15 minutes.
20000
AA Formation at 15 Minutes as a function of Temperature
10000
5000
0
Acrylamide (ppb)
15000
AA = 442.3 * e(.07930*(Temp-383))
380
400
420
Temperature (Kelvin)
440
Effect of pH on Acrylamide
formation
30000
AA (ppb)
25000
20000
120 C, 40 min
150 C, 15 min
15000
10000
5000
0
4
5
6
7
pH
8
9
Prevent asparagine and glucose
reaction
The Idea
Raw
Food
+
Reaction
Inhibitor
+
Cooking
Reduced
Acrylamide
Watchout: The inhibitor(s) must be food safe for
long term (daily) intake from multiple food sources
and should not impact nutritional status.
Acrylamide Precursors – Where to
Intervene
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Reducing levels of precursors:
– Asparagine
– Reducing sugars
– For example: by selecting different varieties of
foods or by different storage or processing
procedures
Asparaginase reduces Acrylamide in
Cooked Potato Products
Potato Product
Acrylamide (ppb)
Control
Asparaginase
Microwaved snack
20,500
1Calculated
164
as (control – asparaginase treated)/control x 100.
%
Reduction1
>99
Asparaginase Experiment on Potato
Product
Washed Russet Burbank Potatoes
Boil for 1 hour
Blend flesh 1:3 with distilled water
45 min @ RT
Asparaginase-treated
Control
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)
Impact of treating with Asparaginase
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By treating with asparaginase there was a
99% reduction in the levels of acrylamide
in the potato mixture following the use of
the microwave
Remove after formation – overview of
some preliminary research
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Supercritical CO2
– removes everything but destroys the product
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UV light
– no effect at several wavelengths including
visible
Insight and recommendations for
Next Steps
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The concerted research and actions by
government, industry and academia have resulted
in rapid progress towards understanding the
mechanisms of formation in food
The notion of “carcinogens” in food is not new
(cooked meat, US National Academy of Sciences
Report1), research by Lois Gold & Bruce Ames
and in numerous research articles
Humans have eaten these foods for millennia
1National
Research Council, 1996. Carcinogens and Anticarcinogens in the Human Diet, ‘A
comparison of naturally occurring and synthetic substance. National Academy Press.
Feasibility of reducing levels
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Removal of substrates must take into account
kinetics of formation along with importance of other
constituents
Preparing foods by cooking at such low temperatures
willl require development of new cooking methods.
Some foods will be impossible to prepare without
temperatures that are high enough to form
acrylamide.
Addition of substances may work for some products
but its too early to evaluate efficacy; could cause
major changes in the foods
There is no precedent for an intervention into the
food supply on this scale; potential to alter
nutritional and/or safety aspects of food
Concluding remarks
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The issue affects a large portion of the
food supply. Lowering acrylamide in one
or a few foods has little effect on long
term intakes - many foods would need to
be altered.
Food cooked at home and in restaurants
represent significant source of acrylamide
exposure and would be less amenable to
intervention strategies.
Concluding remarks (continued)
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Before any interventions are proposed, 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?
Additional information
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Copies of the presentation and or the
original references/presentations can be
provided on request
to Barbara Petersen
([email protected])