Construction of a Pickering interfacial biocatalysis system in skim milk and enzymatic transesterification for enhancement of flavor and quality.

Despite considerable research efforts, lipase catalysis in a fluid milk system with aqueous multicomponent mixtures containing multiple microphases remains challenging. Pickering interfacial biocatalysis (PIB) platforms are typically fabricated with organic solvents or lipids and water. Whether a PIB with excellent catalytic performance can be constructed in complex milk mixtures remains unknown. Here, we challenged PIB with skim milk, a small amount of flaxseed oil, and phytosterols as a model system for transesterification and lipolysis to enhance quality and flavor. The amino-modified mesoporous silica spheres were employed as an emulsifier and carrier of lipase AYS. The conversion of phytosterol esters reached 75.5% at 1.5 h in prepared phytosterol ester-fortified milk with a content of 1.0 g/100 mL. The relative conversion rate remained above 70% after 6 cycles. In addition, the fortified milk showed an intensified and favorable effect on sensory traits through volatile flavor composition analysis. The findings provide a versatile alternative for PIB applications in complex environments, i.e., milk, which might inspire a new bioprocess strategy for dairy products.