Measures to reduce acrylamide in food

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1 Measures to reduce acrylamide in food Koni Grob Official Food Control Authority of the Canton of Zurich, Switzerland ± Known background of AAformation 1. Only relevant source: free asparagine 2. Co-factors: reducing sugars and their thermal degradation products Fructose most efficient Glucose about half as efficient Lactose ~ times less efficient 3. Basic ammonium salts as efficient catalysts Acrylamide formation even at 25 C 1

2 Foods at risk High asparagine: Potatoes High reducing sugar: Bakery ware with honey or inverted sugar Müesli High ammonium Ammonium carbonate to grow dough (hartshorn salt) bakery ware Most relevant foods Absolute acrylamide contents per portion: 1 cup of coffee 2 µg 150 g bread (30 ppb) 5 µg 100 g noodles (20 ppb) 2 µg 30 g crisp bread (500 ppb) 15 µg 50 g müesli (200 ppb) 10 µg 250 g roast potatoes (1000 ppb) 250 µg 200 g French fries (400 ppb) 80 µg 75 g potato chips (500 ppb) 40 µg 100 g gingerbread (800 ppb) 80 µg 2

3 Importance of potato products Mean background exposure without potato products: ~ 10 µg/d (e.g. Swiss Federal Office Public Health) Exposure for moderately high consumption (modestly high consumption must be protected) Product Acrylamide Portion Portions/ Exposure % of (µg/kg) (g) week (µg/d) total Roast potatoes French fries Potato chips Why first potato? Potatoes contain much asparagine: g/kg fresh weight (10-20 g/kg dry weight) ca. 50 times more than wheat flour same heat treatment yields 100 times more acrylamide dark bread crust: <200 ppb acrylamide dark potato crust: ,000 ppb 3

4 Connection to Maillard reaction Acrylamide formation is a special case of the Maillard reaction: fructose or glucose react with asparagine Acrylamide formation is visible No Maillard flavor or browning without acrylamide Measures regarding potatoes 4

5 Potatoes forming less acrylamide Asparagine contents vary little 2950 mg/kg fresh weight ± 26 % (73 samples) Fructose and glucose vary widely 10 to 3000 ppm (factor of 300!) Ammonium varies little 170 mg/kg ± 23 % (12 samples) Improvement through potatoes containing little reducing sugars Well known for chips and French fries! Sugar contents for roasted products Products of good quality with acceptable acrylamide content High red. sugars Dark before crispy High acrylamide Extremely low red. sugars: Weak Maillard (unsatisfactory flavor, color) Dry product Black, bitter sites after strong heating 5

6 Maximum of reducing sugars for roasted potatoes 2500 Acrylamid (µg/kg) Fontane Bintje Desiree Markies Urgenta Charlotte Agria Crispy products prepared by method minimizing acrylamide formation Fructose + Glucose (g/kg Frischgewicht) Conclusion for potatoes At 1 g/kg reducing sugar, optimally prepared roast potatoes of good quality contain 500 µg/kg AA! modest overdoing results in 1000 µg/kg AA! Upper limit for potatoes suitable for roasting: 1 g/kg fresh weight (0.5 g/kg would be preferable) 6

7 Cultivar n Sugar (g/kg) Acrylamid (ppb) Agria Appell Bintje Charlotte cultivar Desiree Eba Fructose glucose Erntestolz in 120 fresh potatoes of Hermes cultivars 199 important in Lady Claire Switzerland Lady Rosetta Markies Contents 109 related to Marlene fresh weight Naturella Nicola Measurements in Panda Nov./Dec Santana (Amrein et al.) Saturna Selection of Storage of potatoes Below 8-10 C potatoes liberate sugar Below 4 C: unacceptably sweet Current practice in Switzerland: Bulk stored at 4 C to hinder sprouting (instead of sprouting inhibitors) Special storage at 8-10 C for chips and French fries; sprouting inhibitors 7

8 Experiment with Erntestolz potatoes Potential of acrylamide formation (µg/kg) Storage at 4 C Storage at 20 C July November Duration of storage (d) Factor of 40! Cooling to 4 C, October-March Potential of Acrylamide formation (µg/kg) x 10 Charlotte Agria x 7.3 Sirtema Ditta x Storage at 4 C (days) 8

9 Sugar contents of potatoes from the Swiss market winter 2002/2003 Glucose + fructose (g/kg fresh weight) Minimum Maximum Mean Nearly all potatoes were from 4 C storage! 4 C during 40 hours (Urgenta, September) Cooling to 4 C for 40 h Three fold increase two days after cooling Storage at room temperature 9

10 Reconditioning at ambient temperature Glucose+fructose (g/kg) before cooling: 0.62 g/kg red. sugar Reconditioning time (days) Bintje potatoes cooled to 4 C in October 2002, reconditioned in March. Potatoes from cooling rooms germinate rapidly! No cooling below 8 C! On the field (late harvest) In the barn before delivery Long-term storage over winter Cooling rooms of distributors Cooling rooms of gastronomy Refrigerator in private homes 10

11 Suitable sugar contents Potato chips (crisps): as low as possible < 0.4 g/kg (fresh weight) French fries: minimal browning required g/kg Roasted potato products g/kg Potatoes sold as suitable for Existing color code for bags according to cooking qualities: A-D (yellow/blue/red/green) Additional golden bag: potatoes with < 1 g/kg red. sugar Suitable for roasted, fried or baked products Potatoes of type B Guidance of consumers Limited availability directed to critical application 11

12 French fries Optimized preparation Usual contents: µg/kg AA Optimization in collaboration with cooks from School of Hotel Management Belvoirpark, Zürich optimum quality with µg/kg AA reduction by factor 5-10 without losing quality 12

13 Relevant parameters 1. Potatoes low in red. sugars 2. Pretreatment Elimination of fines Extraction of sugars and asparagine from surface in warm water; no elimination of starch Acidification with citric acid Pre-frying improves crispiness (140 C) No addition of glucose! 3. Frying Temperature of oil or oven Duration Extraction of potato Frying experiments 160 Acrylamide (µg/kg) Optimum Raw potato Duration of frying (min) Optimum 1 min boiling water 2 h cold water 15 min cold water 15 min boiler water Extraction halves AA formation 13

14 Treatment with citric acid: duration Acrylamide (µg/kg) % citric acid; Charlotte; 200 g/500 ml Cold water noticeably sour Boiler-warm water Time (min) Treatment with citric acid: concentration Acrylamide (µg/kg) min, boiler-warm water; 200 g/500 ml noticeably sour Citric acid (%) 14

15 Frying in oil frozen 8x8 mm prefabricate 600 Acrylamide (µg/kg) Optimum 180 C Optimum 170 C Duration of frying (min) French fries of optimum quality 1. Crispy before brown low sugars extraction of surface 2. Flavor formation requires some browning of points 3. No general browning 15

16 Relevant oil temperature Acrylamide formation at end of process final oil temperature Potatoes cool oil by easily C Amount of potato/oil Power of heating Optimal initial temperature: 170 C Optimal final temperature: C Conclusions for French fries 1. No over frying Acrylamide is formed at end of frying (30 s may more than double) 2. Initial oil temperature of 170 C Prevents local over frying Renders end of frying less critical 10 % rule: 100 g potato/l oil < 100 µg/kg! 16

17 Activities towards implementation Information campaign Jan through media Campaign for gastronomy, Sept Tips and background information through letters Invitation to information meetings Offer for a free analysis Data regarding feasibility Implementation of a GMP value (200 µg/kg?) in some future Roast potatoes 17

Rösti from Agria potatoes Same potatoes; two halves roasted in same pan Left half Storage at 10 C Red. sugar 0.2 g/kg Acrylamide 140 µg/kg Right half Storage at 4 C Red. sugar 3.

18 Rösti from Agria potatoes Same potatoes; two halves roasted in same pan Left half Storage at 10 C Red. sugar 0.2 g/kg Acrylamide 140 µg/kg Right half Storage at 4 C Red. sugar 3.1 g/kg Acrylamide 1020 µg/kg Rösti from Bintje potatoes Left half Storage at 10 C Red. sugar 0.7 g/kg Acrylamide 290 µg/kg Right half Storage at 4 C Red. sugar 6.9 g/kg Acrylamide 2500 µg/kg 18

19 Parameters for optimized Roasting Minimal pre-cooking (firm potato) Enough oil (heat transfer) Minimal temperature to achieve crispiness Timing to achieve crispiness Crispy, gold-brown, no black spots Planned activity Information campaign primarily directed to house holds on Rösti and other roasted potato product Reliable availability of potatoes of low sugar content is a prerequisite (unresolved problem) 19

20 Bakery ware Critical products Crisp bread: extremely high temperature Brown cookies, gingerbread Honey or inverted sugar (reducing sugar) Ammonium carbonate to grow the dough 20

21 Type of sugar Potato as matrix 120 C, 40 min Acrylamide (µg/kg) Increased elimination Sucrose Sugar (%) Fructose Glucose Fructose more efficient than glucose; faster elimination with glucose Yield of acrylamide (%) Influence of matrix Potato Mole ratio fructose/asparagine 1.15 % Asparagine, 120 C/40 min Wheat flour Corn starch Only difference: more ammonium in potatoes 21

22 Effect of Ammonium carbonate Yield of acrylamide (%) Ammonium added % Fructose 0.5 No ammonium added Mole ratio fructose/asparagine Wheat flour 1 % (NH 4 ) 2 CO C/40 min 1.15 % Asparagine Factor of 75! Model experiments Model mixture Acrylamide Elimination (µg/kg) (%) 1 Wheat flour + fructose Na2CO K2CO NH4HCO (NH4)2CO % (NH4)2CO % (NH4)2CO NH4Ac NH4Cl NH4Br (NH4)2SO (NH4)2CO3, Asn x NH3 added to sugar Corn starch + fructose 14 + (NH4)2CO3 < mg/kg Asn % fructose, 1 % of other additions 30 min 150 C 22

23 Dependence on temperature Acrylamide (µg/kg) fructose + NH4 + sucrose no addition + fructose Temperature ( C) Conclusions on temperature Complex because of dependence on elimination! Flour: Maximum AA at 180 C Sucrose does not promote formation, but elimination above 160 C Fructose promotes formation above 100 C; elimination prevails above 140 C Ammonium causes formation above 60 C; elimination prevails above 150 C 23

24 Conclusions on bakery ware Asparagine only relevant precursor, little variable Little influence by sugar concentration in the range of 5-50 % Glucose forms 2-3 times less AA than fructose Higher temperatures may reduce AA Ammonium most important risk factor! Present activity Dialogue with producers Control campaigns with information of the producers Research project ETH Zürich 24

25 Papers on Acrylamide from the Official Food Control Authority of the Canton of Zürich 1. Two GC-MS methods for the analysis of acrylamide in foods. M. Biedermann, S. Biedermann-Brem, A. Noti, K. Grob, P. Egli and H. Mändli. Mitt. Lebensm. Hyg.* 93 (2002) Methods for determining the potential of acrylamide formation and its elimination in raw materials for food preparation, such as potatoes. M. Biedermann, S. Biedermann-Brem, A. Noti, and K. Grob. Mitt. Lebensm. Hyg. 93 (2002) Experiments on acrylamide formation and possibilities to decrease the potential of acrylamide formation in potatoes. M. Biedermann, A. Noti, S. Biedermann-Brem, V.Mozzetti and K. Grob. Mitt. Lebensm. Hyg. 93 (2002) Heated foods: the component eluted next to acrylamide is 2-pyrrolidinone, not 3-buteneamide! M. Biedermann, K. Grob, B. Gutscheand R. Weisshaar. Deutsche Lebensmittel-Rundschau 99 (2003) Comparison of Swiss potato cultivars: potential of acrylamide formation, sugars and free asparagine. T. M. Amrein, S. Bachmann, A. Noti, M. Biedermann, M.Ferraz Barbosa, S. Biedermann-Brem, K. Grob, A. Keiser, P. Realini, F. Escher and R. Amadò. Journal of Agricultural and Food Chemistry, 2003, Vol. 51, No. 18, p French fries with less than 100 µg/kg acrylamide. A collaboration between cooks and analysts. K. Grob, M. Biedermann, S. Biedermann-Brem, A. Noti, D. Imhof, Th. Amrein, A. Pfefferle, D. Bazzocco. Eur. Food Res. Technol. 217 (2003) Storage of potatoes at low temperature should avoided to prevent increased acrylamide formation during frying or roasting. A. Noti, S. Biedermann-Brem, M. Biedermann, K. Grob, P. Albisser and P.Realini. Mitt. Lebensm. Hyg. 94 (2003) Model studies on acrylamide formation in potato, wheat flour and corn starch. M. Biedermann and K. Grob.Mitt. Lebensm. Hyg. (in press) 9. How much reducing sugar may potatoes contain to avoid excessive acrylamide formation during roasting and baking? S. Biedermann-Brem, A. Noti, K. Grob, D. Imhof, D. Bazzocco and A. Pfefferle. Eur. Food Res. Technol. (in press) 10. Comment on Soxhlet extraction of acrylamide from potato chips by J. R. Pedersen and J. O. Olsson, Analyst, 2003, 128, 322. K. Grob a, M.Biedermann a, K. Hoenicke b and R. Gatermann. Analyst (in press) 11. Citric acid to reduce acrylamide formation in French fries and r oasted potatoes? F. Gama-Baumgartner and K. Grob.Mitt. Lebensm. Hyg. (in press) * available through ( htm) 25

Check list for follow up on acrylamide levels according to Commission Recommendation (Document C/2010/9681) Version:

Page 1/10 Check list for follow up on acrylamide levels according to Commission Recommendation (Document C/2010/9681) Version: 18.2.2011 1. Detailed product description: Brand name and product name: Sample....