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

<br />Sorghum (<i>Sorghum bicolor</i> 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, <i>in vitro</i> protein digestibility (<i>IVPD</i>), total phenolic compounds (<i>TPC</i>), antioxidant activity (<i>AoxA</i>), 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%), <i>IVPD</i> (+10%), <i>TPC</i> (+26%), <i>AoxA</i> (+97%). The extrusion increased soluble dietary fibre (+100%) and <i>IVPD</i> (+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 (<i>IC</i>₅₀) 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.