Assessing the Influence of Roasting Process Parameters on Mepiquat and Chlormequat Formation in Dark Barley Malts

The aim of this work was to examine the effect of temperature and time on mepiquat and chlormequat pesticides' formation during the barley malt roasting process. The study was conducted for roasting of green malt and kilned malt. The barley used for the study was of the ecological type and verified by us to be free of any quaternary ammonium pesticides. In our study, we observed the formation of chloromequat (CHLM) along with mepiquat (MPQ). Both the compounds share the similarity in quaternary ammonium structure but to the best of our knowledge, it is the first report where CHLM formation has been observed during the roasting process. Additionally, we tried to study the effect of processing parameters (temperature and time) on the quantity of MPQ and CHLM formed during the process, using response surface methods. Additionally, the effect of process parameters (time and temperature) on the color parameter of luminosity (L*) values was also studied using the response surface methodology. The key factor which determined the amount of compounds produced in the course of roasting was found to be temperature; on the other hand, duration of roasting was observed to be of lesser effect. In the process of roasting dry malt, the CHLM presence was detected at a temperature above 433 K (160 A degrees C), while the MPQ content was found to be present at a temperature above 442 K (169 A degrees C). In the case of green malt, the temperature at CHLM and MPQ content was detected and was found to be higher than kilned malt. We also observed that CHLM formed at lower temperatures and shorter roasting time as compared to MPQ.