Physicochemical Characteristics, Antioxidant and Antibacterial Activities of Selected Raw and Roasted Legumes

The effects of roasting on the color, major and minor compositions of mung bean (Vigna radiata), adzuki bean (Vigna angularis), chickpea (Cicer arietinum L.), and yellow split pea (Pisum sativum L.) were studied. The legume seeds were roasted at 200o C for up to 20min. The corresponding water extracts of both raw and roasted seeds were analyzed for their total phenolic and flavonoid contents, antioxidant and antibacterial activities. Results showed that roasting caused significant changes in color difference index (∆E*ab) of seeds compared to the corresponding flours. Chemical analysis showed that the crude protein, fat, carbohydrate and ash contents increased with roasting time; whereas the moisture and crude fiber contents decreased due to roasting. Results suggested that roasting promoted the structural changes of phenolic compounds and formation of insoluble browning complexes and conjugated compounds, with resultant to the overall decrease in yield percentage and the amount of soluble phenolic contents. Although the formation of Maillardtype reaction products contributed the increase of flavonoid contents and antioxidant activities in chickpea and yellow split pea extracts, they did not exhibit antibacterial activity. Roasting generally increased the availability of nutrients in addition to the enhancement of appearance, but it affected their antioxidant and antibacterial activities.