Foods must definitely contain at least minimal amounts of the amino acid asparagine in order for substantial amounts of acrylamide to be formed. However, the amount of acrylamide formed cannot be predicted based solely on the amount of asparagine found in a food as other factors are involved in the process. When all factors for forming acrylamide are present, it takes approximately 250°F/121°C for the formation of acrylamide in most foods. Acrylamide formation may peak in
temperature ranges commonly used for roasting (250-375°F/121-191°C).
Formation of acrylamide occurs in green tea and coffee beans when roasted at these temperatures. The toasting of wheat bread (also commonly done within this temperature range) has also been shown to increase acrylamide formation. A temperature range of 325-375°F/163-191°C is also frequently used for the deep frying in oil of French fried potato chips and potato crisps. Once again, it is important to realise that the heating of foods at temperatures between 250F-375°F/121-191°C does not automatically mean that acrylamide is being formed in the food. It takes a combination of
the amino acid asparagine together with a form of sugar or the oxidation of fat into smaller carbon molecules, or both, to result in substantial formation of acrylamide.
Acrylamide levels are high in certain canned black olives depending on the specific handling, storage, processing (especially preservation and darkening methods) and heating steps that allow the formation of acrylamide. Olive oil, however, appears to not undergo this process so shows no sign of dangerous levels of acrylamide.
The amount of asparagine in asparagus can increase from 41 to 820 micromoles/gram (dry weight) over the course of post-harvest storage. Only five days of storage were required for those much higher levels of asparagine to be formed in the asparagus. Even though higher levels of acrylamide do not automatically form when asparagine is present in a food and, even though asparagus is not a red flag food when it comes to acrylamide, this relationship suggests that one of the building blocks for acrylamide from asparagine may be more limited when food is cooked in its freshest
The highest risk foods for acrylamide exposure fall into three basic categories:
Fried, processed foods like potato crisps, chips and French fries.
Baked snack foods containing wheat and sugar, including biscuits, cookies and crackers.
Processed foods involving toasted grains, including toasted wheat cereals and roasted grain based coffee substitutes, roasted coffee and cocoa beans (and the chocolate made from them), some dehydrated soup mixes and some canned black pitted olives.
Acrylamide and the human body
Once ingested, acrylamide can be detoxified in the body if it is processed through the cytochrome P450 enzyme system and converted into glycidamide, or if it is hooked together with the sulphur containing, antioxidant molecule called glutathione. Even though the metabolic pathways can help to detoxify acrylamide, humans can still overload the detoxifying capability of these pathways and put themselves at health risk from excess exposure to this substance.
In order to lower the risk of problems from acrylamide, there must be plenty of glutathione on hand in the metabolic reserves. One way to help support glutathione supplies is to consume plenty of sulphur containing foods and especially foods that contain significant amounts of the amino acids cysteine, glutamic acid and glycine which are the key components of glutathione.
Rich sources of cysteine are: broccoli, Brussel sprouts, egg yolks, garlic, oats, onions, poultry, red peppers and yogurt (plain with live cultures).
Rich sources of glutamic acid are: beef, cheese, halibut, kombu, legumes, milk, oily fish, organ meats, poultry and games birds, rabbit, seaweed and venison.
Rich sources of glycine are: alfalfa, beef, cheese, halibut, legumes, milk, oily fish, organ meats, poultry and game birds, rabbit, seaweed and venison.