Effects of ethanol washing on off-flavours removal and protein functionalities of pea protein concentrate

Abstract

This study investigates the effects of treating pea protein concentrate (PPC) with hydroalcoholic solutions on off-flavour removal. Increasing ethanol concentration in the hydroalcoholic solutions from 15 to 75% (v/v) enhanced the removal of volatile compounds contributing to off-flavours such as 1-hexanol, 1-octanol, 3-hexen-1-ol, 1-nonanol and trans-2-hexenal. Differential scanning calorimetry and protein solubility studies showed that higher ethanol concentration induced more protein denaturation as evidenced by the lower enthalpy change and protein solubility of the treated PPC samples. Insoluble protein aggregates formed were hypothesized to be linked by hydrogen bonding. Hydroalcoholic washing of PPC also increased its water holding capacity but reduced oil holding capacity. Ethanol concentrations deployed in the hydroalcoholic solutions influenced gelling behaviour, where increase in PPC gel strength was observed in PPC treated with lower concentrations of ethanol, i.e., 15 and 25% (v/v). However, higher ethanol concentrations, i.e., 50 and 75% (v/v) induced higher extent of insoluble aggregates which weakened the gel network and reduced gel strength. In conclusion, PPC treated with high ethanol concentrations reduced majority of volatile compounds contributing to off-flavour, but significant protein structural changes which could influence product development performance were also observed.