600. Potato crisps. 1000. Soft bread. 150. Breakfast cereals. 400. Biscuits, crackers, crisp bread. 500. Roasted coffee. 450. Instant coffee. 900. Baby foods. 80 ...
September 1-4, 2015 ITO International Research Center, The University of Tokyo
Acrylamide: Formation in Foods and Reactions during Digestion Vural Gökmen Department of Food Engineering Hacettepe University, Ankara, Turkey
Outline Formation in foods • Mechanism, factors • Levels in different foods, indicative values, risk
Reactions and interactions during digestion • Reaction with nucleophiles • A potential mitigation strategy in vitro
• Conversion of intermediates into acrylamide • An increased exposure risk in vivo
Mechanism
asparagine-reducing sugar route Remember •
Acrylamide is generated with a certain rate during heating and accumulated in the reaction medium.
•
Some critical intermediates that may lead to acrylamide under certain conditions also accumulated.
•
Initial concentration of asparagine is important.
Figure Acrylamide formation through the asparaginereducing sugar route (Stadler and Studer, 2015)
Mechanism
asparagine-dicarbonyl route Remember Dicoarbonyl compounds form in foods by means of several mechanisms; • • •
Maillard reaction Sugar dehydration Lipid oxidation
Figure Acrylamide formation through the asparagine– dicarbonyl route (Stadler and Studer, 2015)
Mechanism
confirmation of the intermediates by HRMS
Figure Extracted ion chromatograms of the Asparagine-Glucose model system heated at 180oC for 5 min. Analysis was performed by Thermo Exactive Orbitrap HRMS
Mechanism
food is a pool of different reactive carbonyls Reactive Carbonyl Pool Matrix ingredients
Sugar decomposition products
Maillard reaction intermediates
Lipid oxidation products
Added antioxidants
Figure Different sources of reactive carbonyl compounds affecting the amount of acrylamide formed in foods during heating (Gökmen et al. 2012, Zamora et al. 2008, Hidalgo et al. 2009, Kocadağlı et al. 2012, Zhang and Jin, 2015)
Acrylamide Yield
effect of carbonyl structure • Starting carbonyl structure impacts the conversion ratio of asparagine into acrylamide. • Hydroxyl group of reducing sugars favors the rearrangement of the decarboxylated Amadori compound that leads to higher amounts of acrylamide during heating. • Fructose forms more acrylamide than glucose, due to its lower melting point that means higher mobility and consequently faster interaction of the precursors under dry heating conditions.
Acrylamide Yield
effect of the melting point of carbonyl compound
Conversion ratio, %
6
VAN
5 4 3 2
ASN
FRU CUR SIL ASC
1
DHA
0 50
100
150
200
Melting point, oC Figure Relationship between the melting point of carbonyl compounds and the conversion rate of asparagine into acrylamide during heating at 180 °C
250
Factors Affecting
concentration = f {recipe, process}
Variables related to food and recipe • Asparagine, carbonyls (reducing sugars) • pH, leavening agents (ammonium bicarbonate), cations (calcium), other amino acids (glycine) • Shape and dimension (strip, disk)
Variables related process • t/T (thermal load)
Asparagine the limiting factor
Acrylamide, ng/g
4000 3000 2000 1000 0 0
200
400
600
800
1000
Asparagine, mg/kg Figure Asparagine is limiting factor for acrylamide formation in cereal products. Whole grain products contain more asparagine.
Bread crust baked @ 180oC x 30 min
Sugars
different reactivity
Acrylamide, ng/g
400
Sucrose Glucose
300 200 100 0 0
10 20 Sugar content, %
30
40
Gökmen, V., Açar, Ö.Ç., Köksel, H., Acar, J. (2007) Food Chemistry 104, 1136-1142
Cookie baked @ 205oC x 11 min
time-Temperature excess asparagine Acrylamide, ng/g
1600 3 min 1200
6 min 9 min
800 400 0 140
160
180
200
Frying temperature, oC Gökmen, V., Palazoglu, T.K., Senyuva, H.Z. (2006) Journal of Food Engineering 77, 972-976
French fries Fried in oil
time-Temperature asparagine limited Acrylamide, ng/g
500 400 300 200 100 0 0
20
40
60
Roasting time, min Kocadağlı T, Göncüoğlu N, Hamzalıoğlu A, Gökmen v (2012) Food & Function (in review)
Coffee roasted @220oC
Other ingredients Acrylamide, ng/g
400
Acrylamide 300
200
100
0
Standard recipe
Ammonium replaced
Reducing Ammonium Asparaginase sugar and reducing added replaced sugar replaced Acrylamide Toolbox
p // 1
Acrylamide Levels occurrence in foods
Data from 2010 survey (values in ppb)
Food category
n
Median
Mean
Maximum
French fries
256
240
338
2174
Potato crisps
242
450
675
4533
Soft bread
150
18
30
425
Breakfast cereals
174
91
138
1290
Biscuits, crackers, crisp breads
462
129
333
5849
Roasted coffee
103
200
256
1932
Instant coffee
15
520
1123
8044
Baby foods
128
15
38
677
EFSA has reconfirmed previous evaluations that acrylamide in food potentially increases the risk of developing cancer for consumers in all age groups (July 2015).
Acrylamide Exposure main contributors vary by age
• Adults • Fried potato products up to 49%, coffee up to 34%, soft bread up to 23% • Children • Fried potato products (except crisps and snacks) up to 51%, soft bread, breakfast cereals, biscuits etc. up to 25% • Infants • Baby foods other than processed cereal-based up to 60%
Acrylamide Levels indicative values
Food category
Indicative value, ppb
French fries
600
Potato crisps
1000
Soft bread
150
Breakfast cereals
400
Biscuits, crackers, crisp bread
500
Roasted coffee
450
Instant coffee
900
Baby foods
80
Commission Recommendation November 2013 The European Commission has introduced indicative values for those food groups considered to contribute the most to consumer dietary exposure (2013/647/EU). Indicative values are not maximum limits and are intended as a guide to initiate prompt investigation when higher levels occur.
In vitro Digestion Study selected foods
• Sweet biscuits and crackers • Low in asparagine, low or high in reducing sugars • Low or high in acrylamide, possibly low in critical intermediates that lead to acrylamide during digestion process
• Fried potato products • High in asparagine, high in reducing sugars • High in acrylamide and possibly in critical intermediates
INFOGEST procedure
Processed Foods • Potato chips • French fries • Sweet biscuits • Crackers
Oral Phase Simulating Saliva Fluid 2 min
Gastric Phase Simulating Gastric Fluid Pepsin, pH 2.0 37oC x 2 h Duodenal Phase Simulating Duodenal Fluid Bile salts, Pancreatin, pH 7.5 37oC x 2 h Colon Phase Protease, pH 8.0 37oC x 2 h Viscozyme L, pH 8.0 37oC x 16 h
In vitro Digestion results of different biscuits
Acrylamide (μmol)
25 biscuit1 20
biscuit2 biscuit3
15 10 5 0
initial
gastric
duodenal
colon
Model System
reaction with nucleophiles Table. Changes in acrylamide content of different model systems during in vitro enzymatic digestion Model System
Acrylamide, μmol Initial level
gastric phase
duodenal phase
colon phase
Acrylamide (control)
10.25 ±0.56 a
9.29±0.19 a,b
8.10 ±0.07 b,c
7.79 ±0.05 c
Acrylamide-Lysine
10.25 ±0.56 a
8.22±0.01 b,c
8.27 ±1.25 b,c
8.36 ±0.43 b,c
Acrylamide-Cysteine*
10.25 ±0.56 a
8.31 ±0.13 b,c
5.32 ±0.77 d
4.02 ±0.41 e
* Acrylamide level significantly decreases (p