Effects of processing on phytochemical profiles and biological activities for production of sorghum tea

The present study was undertaken to assess the changes of phytochemical profiles, antioxidant, α-glucosidase and α-amylase inhibitory activities of sorghum grain during the processes of sorghum tea production. Significant (p < 0.05) changes of total phenolics (TPC), total flavonoids (TFC) and procyanidins (PAC) contents were found in sorghum grains during soaking, steaming and roasting processing. Significant (p < 0.05) increases of ferulic (free) and p-coumaric acid (bound) were present in sorghum upon steaming processing. Roasting processing (150 °C, 1 h) caused significant (p < 0.05) increases in phenolic acids, TPC, TFC and PAC compared with the soaking and steaming stages. Accompanied with the changes of phytochemicals of sorghum grain, there were complex changes of biological activities during the successive processes. Our study also showed that there were positive linear correlations between TPC, TFC, PAC and bioactivities of sorghum grain, however, PAC has the strongest correlation (0.979, 0.968 and 0.912, respectively, p < 0.0001) with DPPH radical-scavenging activity, α-glucosidase and α-amylase inhibitory activities.

► We assessed the changes in phytochemicals and bioactivities during the processing of sorghum tea. ► Processing induced complex changes in phytochemical levels. ► Processing changed antioxidant, α-glucosidase and α-amylase inhibitory activities of sorghum. ► Positive linear correlations between phytochemicals and bioactivities were found.