Impact of thermal treatment and fermentation by lactic acid bacteria on sorghum metabolite changes, their antioxidant and antidiabetic activities

This study evaluated the impact of thermal treatment and lactic acid bacteria fermentation of sorghum on the antioxidant, antidiabetic, nutritional and metabolite profiles. Wet cooking and pressurized cooking improved the antioxidant capacity compared to raw. Fermentation of wet cooked (H95F) and pressurized cooked samples (H121F) further enhanced the ABTS and DPPH antioxidant capacity by 2.4 and 2.0 times; and 1.5 and 1.8 times higher than raw, respectively. Pediococcus acidilactici OHFR1 fermentation of sorghum M20 genotype after wet cooking at 60 °C, 80 °C and 95 °C significantly decreased α-glucosidase inhibition to 39.1%, 40.6% and 46.4%, respectively, compared to raw (51.6%). However, α-glucosidase inhibition significantly increased to 70.1% after pressurized cooking and fermentation. Overall, 28 metabolites including phenolic compounds, amino acids and their derivatives, peptides and microbial metabolites were identified in sorghum M20 using UHPLC-Q-TOF-MS/MS non-targeted approach after treatments. Compared to the raw sorghum sample, wet cooking and pressurized cooking resulted in 9 differential metabolites each. Fermentation after wet and pressurized cooking resulted in 4 and 14 differential metabolites, respectively, compared to the raw. These findings confirm the potential of thermal treatment and fermentation to significantly modify sorghum bioactive components and their use as functional ingredients in the management of diabetes.