1. EXAMINATION OF THE EFFECT OF DOMESTIC COOKING ON ACRYLAMIDE LEVELS IN FOOD Rachel Burch Leatherhead Food International

2. Objectives To compile a list of foods relevant to home cooking that are high in asparagine, taking into account levels of consumption To examine the effect of cooking on acrylamide levels of less complex foods (i.e. vegetables) To examine varietal effects in potatoes

3. Total quantities (grams) of vegetables and vegetable products consumed in 7 days (consumers only) Type of food Total quantities (grams) consumed in 7 days MeanMedian% consumers Green beans1089022 Leafy green vegetables15210853 Carrots – not raw1068556 Tomatoes – not raw1318524 Other vegetables22617080 Potatoes Potato chips34827071 Other fried/roast potatoes and products20317542 Potato products – not fried1461206 Other potatoes and potato dishes46939684 NDNS data, 2002

4. Asparagine and glutamine levels Asparagine mg/100g fresh weight Glutamine mg/100g fresh weight Carrots25-11037-123 Tomatoes16.6 Onions33-55 Cauliflower740 Mushrooms12-17 Broccoli716 Green bean pods1875 Kale16107 Spinach639 Potatoes13394

5. Task 3a Potatoes cooked from fresh and from frozen –Baked, boiled, roast, saute, microwave “baked” from fresh –Boiled, roast, saute from frozen Onions cooked from fresh and from frozen –Boiled, baked, fried from fresh and frozen

6. Task 3a – Potatoes

7. Task 3a – Onions

8. Task 3c – Cyclic re-use of frying oils Five different oil types Five cookings in each oil –Initial cookings to same colour, to determine fry time for each oil. Subsequent cookings for the same length of time –Oil temperature 190ºC (except lard: 175ºC)

9. Use of different cooking oils

10. Re-use of cooking oils

11. Re-use of cooking oils - conclusions Preliminary data suggests: –Some differences in acrylamide levels in chips cooked in different oils –Some indication that acrylamide levels increase in chips cooked in re-used rapeseed oils

12. Task 3d – Effect of pre-treatment Chips –Washing, storing in water for 30 mins, storing in water for 2 hours –Samples prepared in triplicate, chips cooked for same length of time Roast potatoes –Washing, storing in water for 30 mins, storing in water for 2 hours, par-boiling –Samples prepared in triplicate, cooked for same length of time except for par-boiled

13. Task 3d – Effect of pre-treatment - Chips

14. Chips – correlation with colour greenred

15. Chips – correlation with colour L Value DarkLight

16. Pre-treatment – Chips – glucose removed

17. Task 3d – Effect of pre-treatment – roast potatoes

18. Pre-treatment – roast potatoes – glucose removed

19. Effect of variety - chips

20. Effect of variety – Roast potatoes

21. Effect of variety – baked potatoes

22. Conclusions – factors affecting acrylamide formation in domestic cooking Type of cooking –Acrylamide formed in roasted, sautéed, oven baked potatoes, higher levels found in potatoes cooked after freezing –Not formed in boiled or microwaved potatoes –Formed in fried onions, onions baked from frozen –Not formed in onions baked from fresh, or boiled Pre-treatments –Soaking for two hours, or par-boiling led to greatest reductions –Indication that some pre-treatments affect fat content

23. Conclusions – factors affecting acrylamide formation in domestic cooking Chip colour correlates to acrylamide levels, roast potato colour does not –Roast potatoes were not of uniform size and shape Variety –Some varieties result in higher acrylamide levels relative to other varieties cooked using the same method