Horse gram (Macrotyloma uniflorum Lam. Verdc.), although an underutilized pulse it is an excellent source of protein, dietary fiber, variety of micronutrients and is also traditionally used in various herbal therapeutic formulations. The present study advances the knowledge on impact of soaking, germination, cooking and fermentation on major bioactive compounds in horse gram seeds. Changes occurring in phenolic compounds, protein content, free amino acids, free radical scavenging activity, ?-amylase and ?- glucosidase enzyme inhibition activities as well as volatile compounds were determined in horse gram seeds as well as sprouts. It was also observed that germination of horse gram seeds for 72 h significantly increased DPPH free radical scavenging activity, most of the essential amino acids content except threonine, ?-amylase and ?-glucosidase inhibition activity. Cooking significantly increased DPPH free radical scavenging activity of horse gram sprouts while free amino acid content, ?-amylase and ?-glucosidase inhibition activity was reduced compared to fresh horse gram sprouts. Fermentation of horse gram sprouts by Lb. plantarum NRRL-B-4496 and Lb. plantarum NCDO-1193 for 48h also further increased the DPPH free radical scavenging activity, free amino acid content, ?- amylase and ?-glucosidase inhibition activity. HPLC-DAD-ESI/MS analysis of all the samples indicates changes in phenolic compounds during processes such as germination, cooking and fermentation. Such result can be attributed to conversion of glycosylated phenolic compounds to their more bioavailable forms i.e. aglycones such as kaempferol. Differences in free radical scavenging activity and total phenolic content indicate the presence of certain metabolites other than phenolic compounds with potent antioxidant activity. Microbiological analysis determined that both lactic acid bacterial strains were able to utilize horse gram sprouts for optimum growth during 48h fermentation period. A total of 40 volatile compounds were detected using head-space solid phase micro extraction combined with GC-MS. Qualitative as well as quantitative changes in volatile compounds was determined during germination and fermentation of horse gram sprouts for 24h (day 1), 48h (day 2), 72h (day 3), 96h (day 4), 120h (day 5) by Lb. plantarum NRRL-B-4496 and Lb. plantarum NCDO-1193 as well as during natural fermentation. A remarkable increase in the amount of some organic acids such as acetic acid, alcohols and some volatile phenols such as eugenol was observed with increasing fermentation time. The results suggest that germination and lactic acid bacterial fermentation of horse gram seeds and sprouts respectively influences the levels of majority of the investigated bioactive compounds. Therefore, the present study supports the rationale that conventional processes facilitates release of bound compounds, conversion of complex metabolites to its more bioavailable form and biosynthesis of certain compounds with sensory as well as potential health benefits in addition of delivering probiotic characteristics to the consumers
ETD Chair
Patil, Bhimanagouda Leonard Pike Inagural University Professor and Interim Head, Food Science and Technology
