Effects of different drying methods on the flavonoid profiles of Shatianyu (Citrus grandis L. Osbeck) whole fruit and in vitro bioactivity

The profile and bioactivity of flavonoids in Shatianyu ( Citrus grandis L. Osbeck) whole fruit powder (SWFP) prepared by hot air, heat pump, vacuum freeze, spray and microwave drying were explored, respectively. SWFP exhibited comparable total flavonoid contents (TFC) to Shatianyu homogenate except for spray-dried SWFP, which exhibited a higher TFC. Nine flavonoids were detected in SWFP. Naringin, cigranoside B, melitidin and bergamjuicin were the major flavonoid components, and their content accounted for 94.2%-96.7% of the total contents of detected flavonoids. Furthermore, cigranoside C, D and F, which were isolated from Shatianyu pulp with new structure in our previous study, were also detected in all SWFP with the contents of 0.47-0.87, 0.02-0.86 and 0.08-0.27 mg/g DW, respectively. In addition, SWFP generally showed approximate antioxidant activity but higher pancreatic lipase inhibitory activity compared with Shatianyu homogenate except for spray-dried SWFP, which exhibited higher antioxidant activity but lower pancreatic lipase inhibitory activity than those of homogenate. Thus, Shatianyu flavonoids are not heat-sensitive. SWFP are natural antioxidants and pancreatic lipase inhibitors, and could be used as functional ingredients for developing anti-obesity related healthy food. • Flavonoids in Citrus grandis Shatianyu are stable during different drying process. • Spray-dried Shatianyu whole fruit powder (SWFP) had the highest flavonoid content. • SWFP flavonoids are dominated by naringin, cigranoside B, melitidin, bergamjuicin. • SWFP are natural antioxidants and pancreatic lipase inhibitors.