GERMINATION AS A STRATEGY TO VALORIZE SORGHUM GRAINS (SORGHUM BICOLOR (L.) MOENCH) IN HUMAN FOOD: PHENOLIC COMPOUNDS PROFILE AND BIOACCESSIBILITY UPON SIMULATED DIGESTION

Climate oscillations highlight the need for new sustainable sources to maintain global food security. Sorghum is the most promising candidate crop for food supplies, due to its agronomic advantages. From a nutritional perspective, sorghum is a gluten-free cereal with remarkable levels of phenolic compounds (PC). The application of bioprocesses, such as germination, can increase PC release reduce anti-nutritional factors, e.g., tannins and their negative impact on grain digestibility. This study focused on the germination effect in sorghum PC profile, bioaccessibility and in vitro antioxidant capacity. Sorghum grains from two genotypes (Macia: caudatum; and IS30400: hybrid kafir-caudatum; without and with tannins, respectively) were germinated at 16°C and 60% of relative humidity until 144 h corresponding a thermal time of 720 C°.h. The non-germinated grains were used as control. Free (FPC) and bound (BPC) PC were sequentially extracted and analyzed by high-resolution untargeted metabolomics (UPLC-ESI-QTOF/MS). In vitro antioxidant capacity and bioaccessibility were determined by microplate-based DPPH and INFOGEST methods, respectively. Globally, 118 PC were annotated, with 84 PC found in common to both genotypes. PCA analysis evidenced the phenolic profile variation between the non-germinated genotypes: flavonoids (52%) and phenolic acids (48%) were the major classes in Macia and IS30400, respectively. Germination decreased total ion abundance but favored the flavonoids release/synthesis, mainly dihydroquercetin. Even with lower ion abundance, the antioxidant capacity and FPC/BPC ratio increased in caudatum (+26%; 1.15 to 1.54) and hybrid (+66%; 0.55 to 1.34) sorghum. These results suggested endogenous enzymatic reactions during germination released PC previously complexed to the cell matrix, suggesting the better absorption by the human body. Germination greatly impact the in vitro bioaccessibility, and these PC are mainly released at the gastric digestion phase (+20%). This work can stimulate sorghum consumption and germination as a viable option for the development of sorghum-based foods with improved bioactive properties.