Effects of spray-drying conditions on functional properties of bioactive compounds extracted from lotus leaf
Pham Van Hung, Pham Ngoc Cam Ha
In order to determine effects of spray-drying conditions on functional properties of lotus leaf extract, total phenolic content (TPC), total flavonoid content (TFC), alpha-amylase inhibitory, alpha-glucosidase inhibitory and DPPH scavenging activities of the extracts before and after spray-drying at different temperatures and carrier concentrations were investigated. Lotus leaf was extracted by 75% ethanol in 20 min for three times and then concentrated to 50% (v/v) by vacuum evaporator. Maltodextrin and gelatin were used as carriers in spray drying process with the ratio 7:3 (w/w) and at concentrations of 10, 20 and 30% (w/v). The mixtures of carriers and extract were dried in spray drying chamber with 400 mL/min feed rate, 1.2 – 1.3 bar air pressure, 10 rpm pump speed and air inlet temperature at 130, 150, 170 and 190 oC. TPC, TFC and bio-functional properties of the extracts were found to have strong correlation which suggested that the phenolic compounds presented in the extract were responsible for the DPPH radical scavenging capacity and alpha-amylase and alpha-glucosidase inhibition activities. Significant loss on TPC and TFC (28.74 to 40.63% and 25.52 to 36.87%, respectively) resulted in the decrement of DPPH scavenging capacity and alpha-amylase and alpha-glucosidase inhibition activities after spray-drying. In this study, the highest TPC and TFC recovery (79.24% and 81.87%, respectively) were obtained after spray-drying at 130 oC and 20% of carrier concentration.