Combining germination-extrusion as strategy to improve nutritional and nutraceutical value of whole sorghum grain

Sorghum (Sorghum bicolor L.) is one of the most important cereals in the world; is an important source of bioactive compounds. The germination is a very useful tool to improve the nutraceutical value of cereals, associated with the reduction of chronic-degenerative diseases; the extrusion has a positive effect on microbiological stability and sensory properties. The response of the combined germination-extrusion processes applied under optimised conditions, on proximal composition, in vitro protein digestibility (IVPD), total phenolic compounds (TPC), antioxidant activity (AoxA), hypoglycemic potential and microbiological quality of sorghum grains were studied. Sorghum was processed by germination (37 °C for 69 h) and extrusion [137 °C for 134 rpm (revolutions per minute)]. The germination increased protein content (+21%), insoluble dietary fibre (+50%), IVPD (+10%), TPC (+26%), AoxA (+97%). The extrusion increased soluble dietary fibre (+100%) and IVPD (+13%). The combined germination-extrusion processing reduced the content of total coliforms, total mesophilic aerobics and molds below the maximum limits established by the Mexican Official Standards NOM-147-SSA1-1994. Regarding hypoglycemic potential, germinated sorghum and germinated-extruded sorghum presented the best half maximal inhibitory concentration (IC50) value. The combination of germination-extrusion processes is an effective strategy to increase bioactive compounds with antioxidant activity and inhibition of α-amylase and α-glucosidase enzymes.