Effects of moisture regulation and heat treatment synergy on structural properties and digestibility of jackfruit seed starch.

To investigate the impact of moisture regulation and heat treatment synergy on the structural properties and digestibility of jackfruit seed starch (JSS), starch samples underwent heat-moisture treatment (HMT) and annealing treatment (ANN) with varying moisture content (10-30 % for HMT at 120 °C, and 50-90 % for ANN at 40 °C). The physicochemical properties and in vitro digestibility of modified-JSS were systematically investigated. Results showed that the birefringence intensity of HMT-JSS decreased at high moisture levels but remained unchanged for HMT-JSS and ANN-JSS at low moisture levels. As moisture content increased for HMT and ANN, the amylose content and relative crystallinity increased and then slightly decreased. The gelatinization temperatures increased while enthalpy and viscosity declined. At high moisture content, the infrared absorbance ratio of 1047 cm/1022 cm decreased on HMT but increased on ANN. Resistant starch (RS) contents of both HMT-JSS and ANN-JSS were increased at appropriate moisture levels (10-15 % for HMT, 50-80 % for ANN), but decreased with excessive moisture. Besides, these changes were more pronounced on HMT than ANN. Correlation analysis showed that the RS was significantly affected by the short-range ordered structure during HMT and ANN. These results revealed that hydrothermal treatment efficiently modified the structure properties and digestibility of JSS.