Improvement of physicochemical properties and stabilization of oat milk by composite enzymatic hydrolysis

This study aimed to examine the impact of composite enzymatic treatment on the physicochemical properties of oat milk, which would provide an effective strategy to improve the stability of plant-based milk. Oat milks treated with individual α-amylase or in combination with the protein glutaminase were produced. The result indicated that composite enzyme treatment significantly changed the physicochemical properties and significantly improved the stability of oat milk. Compared to original oat milk, a significant reduction in droplet size was observed in oat milk treated by α-amylase and composite enzymatic hydrolysis, with mean droplet size decreasing from 12.611 to 9.638 and 9.533 μm, respectively. And the microstructure of well-distributed droplets suggested that the aggregation in oat milk was effectively inhibited by composite enzymatic treatment of α-amylase (1.5 %) and protein glutaminase (0.3 %). Oat milk was characterized as a pseudoplastic fluid and dominated by elastic structure. Moreover, the rheological properties of oat milk were pronouncedly enhanced by enzymatic treatments, with a higher apparent viscosity and moduli presented. Physical stability revealed that within enzymatic treatment, especially for the composite enzymes, the long-term stabilization of oat milk was improved, presenting a lower TSI profile. Furthermore, the environmental stresses of oat milk subjected to composite enzymatic hydrolysis were evaluated, and suggested that this oat milk was relatively stable in neutral and alkaline conditions, also being stable in moderate temperature and ionic strength. Hence, this study demonstrated that the stabilization of oat milk was significantly improved by the composite enzymatic treatment, and exhibited good stability in environmental stresses, which was potentially useful in the application of plant-based milk. This study would provide valuable insights into improving the stability of oat milk in the further industry.