Acrylamide in wheat products

Acrylamide is a substance classified as carcinogenic that can be formed when starchy products such as potatoes and cereals are exposed to high temperatures. Deep-fried potato products in particular, such as crisps and chips, have high acrylamide concentrations, but acrylamide can also be detected in most cereal products, albeit in higher concentrations, especially in biscuits, gingerbread and crispbread. In bread, over 95% of acrylamide is found in the crust and hardly any acrylamide in the crumb, and as bread consists mainly of crumb, acrylamide is not an issue. The EU Commission has lowered the reference value for acrylamide in wheat bread to 50 µg/kg and is currently working on binding threshold values.

We have undertaken extensive studies with the aim of analysing various options along the wheat supply chain for their potential to reduce acrylamide. Acrylamide does not occur in cereal grains and flour, but is only formed from reducing sugars (glucose, fructose, maltose) and the amino acid free asparagine when exposed to high temperatures. In this respect, the amount of acrylamide to be expected cannot be measured directly from the flour. However, we were able to clearly confirm data from the literature that the content of free asparagine in whole grain flour correlates very closely with the amount of acrylamide in the end product, both in baked goods and in breakfast pops. Thus, the determination of free asparagine in whole grain flours can be taken as a good predictor of the amount of acrylamide to be expected in the final product using high heat treatment.

We have therefore carried out numerous other experiments in which the amount of free asparagine was measured as a function of various operations along the supply chain. We were able to clearly show that there are large differences in the free asparagine content between the individual cultivars of wheat, durum, spelt, emmer and einkorn. This means that the risk of acrylamide could be almost halved by the choice of cultivar. In the long term, it would even be possible to further reduce the content of free asparagine in wheat through targeted selection. A few prost registration cultivar trials in Germany have been measuring and reporting the free asparagine content of the tested wheat cultivars for a few years now. Reduced nitrogen fertilisation also leads to reduced levels of free asparagine in flour, but is only recommended in combination with the choice of cultivar and in consideration of baking quality. The baker can further reduce the acrylamide risk by extending the dough fermentation time. In addition, whole grain flour contains significantly more free asparagine than fine flour. However, it should be pointed out that whole grain flour has many nutritional advantages for us humans compared to fine flour. Therefore, we do not recommend increased consumption of fine flour, but that other methods are used to reduce the acrylamide content in products made from whole grains, where possibly higher levels of acrylamide are to be expected (crispbread) (less heat during baking, use of asparaginase, choice of wheat variety, etc.).

Other reduction options that we have not investigated include reducing the baking temperature and duration, using technical enzymes and avoiding sulphur deficiency in soils during grain production. Thus, numerous options exist to sustainably reduce the acrylamide risk along the wheat supply chain. However, a rough estimate for the German wheat market indicates that a maximum of 10% of the wheat produced in Germany is used for end products in which acrylamide could come close to the future EU reference values. It remains a question of how the entire supply chain can work together to solve this problem in the future. More information here.