Activity: Talks and presentations › Conference presentations
Most food for human consumption is processed before eaten. This is especially the case for cereals, which always will be processed by at least one of the following processing step and often two or more in combinations: De-hulling, milling, boiling, steaming, frying, baking, fermenting, malting, brewing, and distilling. All these processes will influence the pesticide residues in different ways and to different degrees.
The EU Reference Laboratory for Pesticide Residues in Cereals and Feeds have performed processing studies on milling, baking and beer brewing. The studies has been performed with barley, oat, rye and wheat with incurred pesticides. The cereals were leftovers from proficiency test material. The milling studies confirmed that pesticide residues was to be found mainly in the outer part of the kernels, showing that up to 60 % of the residues were present in the bran. Processing factors for grains to bran were around 2.5.
A study on the fate of pesticide residues during baking was performed with using bran biscuit as a model for the baking process. The procedure used for producing the biscuit mimics the representative domestic standard of biscuit OECD guidelines (2008). The ingredients were; cereal bran, baking powder, sugar, salt, butter, and milk. From the doughs small round biscuit measuring 5cmx1 cm were made. The biscuits were baked at three different temperature/time combinations in a temperature-controlled oven, 1) 200°C for 6 min, 180°C for 25 min, and 200°C for 20 min. Seven different bran were used for the study. In general, the results showed small changes in residues after backing (<20%) , depending on their physico-chemical properties.
Finally, we currently study the fate of pesticides in beer brewing. The pesticides are introduced by unmalted grains (called adjuncts). So far barley, rye and wheat has been used as adjuncts. Previous studies show that the level of pesticides decreases significantly during malting but information on pesticides introduced through unmalted grains is scarce. The brewing was carried out in laboratory scale where mashing was performed at 10 L with 1/3 of the grain bill as adjuncts and 2/3 as standard pilsner malt (Weyermann). The worts were boiled with and without hops (Magnum) and fermented with a SafLager W-34/70 yeast. Sampling of process intermediates and by-products was performed throughout the process. The preliminary results from analysing wort, spent grain and beer showed that the pesticides residues present in all these sample types.