The Digestibility and Thermal Properties of Fermented Flaxseed Protein

Abstract

Abstract The effects of solid fermentation conditions such as the incubation period, fermentation temperature, initial pH, and inoculum concentration on protease production and in vitro digestibility of flaxseed protein with Aspergillus oryzae 3.951 were reported. From 72h of fermentation at 30 °C, protease activity and protein digestibility were significantly increased. Maximum protease activity was obtained for high temperature-pressed flaxseed meal (HFM) and cold-pressed flaxseed meal (CFM) with initial pH 4.4-5.2, inoculum concentration 0.5×106 spores /mL. The results showed that the melting temperature (Td) increased by 4.8 °C and 7.6 °C for fermented CFM and HFM, respectively. In DSC tests, the enthalpy value is defined as the quantity of heat absorbed by samples during warming process. Results indicate that the enthalpy value of fermented samples significantly reduced from 186.5 J/g to 148.9 J/g (CFM) and from 187.0 J/g to 163.3 J/g (HFM). The result suggests that the lower molecular weight protein was degraded by protease, and the remaining were globulin with greater thermal stability and higher molecular weight.