Influence of alcohol washing on the flavour profiles, protein quality, and functionality of canola and sunflower proteins

Abstract

The goal of this research was to examine the effect of alcohol washing (ethanol and isopropanol; concentrations of 35%, 65%, and 95%) on the flavour profiles, protein quality, and functionality of oilseed protein isolates (canola and sunflower). The 35% ethanol wash increased the water and oil holding capacity of canola and sunflower proteins the most. Ethanol was also more effective than isopropanol at improving the foaming capacity of the protein isolates. Protein solubility decreased after most treatments except for 95% ethanol or isopropanol washing of canola protein. The volatile compounds 2-butenal, 2-methylbutenal, and 3-methylbutanal were the predominant aldehydes reduced from canola protein by alcohol washing. For sunflower protein, 95% isopropanol washing reduced or eliminated many of the volatile organic compounds (e.g., hexanal, nonanal, 3-methylbutanal). Lower alcohol concentrations were more effective at reducing the non-volatile flavour compounds, sinapine and chlorogenic acid, in canola and sunflower, respectively. Only canola protein had improvements in the in vitro protein digestibility corrected amino acid score after alcohol washing. Overall, alcohol washing with 35% ethanol is recommended for canola protein and 65% isopropanol for sunflower protein to improve flavour compound profiles while also preserving many functional properties. However, these treatments lower protein solubility, making the ingredients more suitable for food applications that do not require full dispersibility.