Effect of microwave field on trypsin inhibitors activity and protein quality of broad bean seeds (Vicia faba var. major).

BACKGROUND In human nutrition legume seeds are usually subjected to soaking and thermal processes, mainly by using traditional cooking method. This method which has been used for decades, does not allow to control and adjust the parameters of this process. Therefore it does not seem to be the optimal method. Undoubtedly, microwave field is an alternative thermal process to conventional technique. The aim of this study was to assess the impact of microwave field on the activity of trypsin inhibitors and protein quality of three varieties of broad bean seeds. MATERIAL AND METHODS The study was performed on dry seeds of broad bean varieties Windsor White, Bachus and Basta. The seeds were soaked and heated in a microwave. The seeds absorbed different energy doses from 500 J/g, through 750, 1000, 1250, 1500, 1750 to 2000 J/g. The study material prepared in this way was tested for trypsin inhibitor activity, protein solubility and in vitro protein digestibility. The results were analysed by the one-way analysis of variance. RESULTS Microwave heating resulted in decreased activity of trypsin inhibitors and protein solubility and increased digestibility of protein in all tested varieties of broad bean seeds. With increasing doses of the microwave field energy a decrease in protein solubility was observed. Satisfactory reduction in trypsin inhibitors at the level of 70-75% and highest protein digestibility were obtained by using a microwave field with energy dose of 1000 J/g of seeds. CONCLUSION It can be concluded that the optimal dose of microwave energy field which will produce a relatively low activity of trypsin inhibitors and the highest protein digestibility together with maintaining solubility of broad been seeds was 1000 J/g seed.