Acrylamide: Formation in Foods and Reactions during ...

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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