A comparative study on stability and flavor of additive-free oat milk obtained by different heat pretreatments (blanching and microwave) of oat kernels

Abstract

Heat pretreatment of oat kernels is necessary in flavor improvement, but its impact on the stability of so-called “clean label” oat milk has not yet been studied. Therefore, two heat pretreatments, including blanching (BC, 90 °C for 5 min) and microwave (MW, 400 W for 5 min), as well as their combination (BC + MW), were compared in this study. The results showed that after the three treatments, the lipase activity of oat kernels was reduced by 50% or more, and stability of oat milk was significantly improved compared to the control. Furthermore, oat milk with BC treatment exhibited the best stability, accompanied by smallest particle size, surface tension, and fluorescence intensity, as well as highest values of zeta potential, apparent viscosity, surface hydrophobicity, and the total content of α-helix and β-sheet, followed by MW and BC + MW. For the flavor compounds analysis results, BC treatment was sufficient to reduce off-flavor compounds (such as hexanal, nonanal, and 2-pentylfuran etc.) in oat milk, achieving the best sensory quality. This study first confirmed the positive effect of appropriate heat pretreatment (BC) of oat kernels on the stability and overall quality improvement of additive-free oat milk.