Improvement on Ca2+ tolerance of insect-based milk based on pH-shifting treatment combined with dynamic high pressure microfluidization

Abstract

Milk is both the main source of high-quality protein and the important carrier of calcium supplementation. In the process of developing artificial simulated milk, the addition of calcium must be considered to improve nutritional value but ionic calcium tends to impair the stability of the emulsion system. Against this background, pH-shifting treatment combined with dynamic high pressure microfluidization (DHPM) was proposed to improve the Ca 2+ tolerance of milk substitute. That is, the protein was modified by pH-shifting treatment and then mixed with oil phase by DHPM to prepare Ca 2+ -tolerant emulsion. In this paper, an insect-based emulsion system was constructed by this method to simulate milk, in which the silkworm pupae water-soluble protein (SPWP) was used as an emulsifier after pH-shifting treatment, and the physical stability of the emulsion to Ca 2+ was demonstrated by measuring particle size, ζ-potential and Turbiscan stability index. The effect of pH-shifting treatment on SPWP structure was characterized by surface free sulfhydryl group content, surface hydrophobicity, Tryptophan fluorescence and UV Spectra. Interestingly, the SPWP-stabilized emulsion containing 65 mM calcium lactate could keep stable after low pasteurization, showing negligible phase separation within five-day storage at 4 °C. This study is not only instructive for the development of milk substitutes, but also provides a potential solution to environmental and sustainable issues in the food industry system. • Insect protein was used to prepare the milk substitute. • Ca 2+ tolerance of milk substitute was improved by pH shift and dynamic high pressure microfluidization. • Ca 2+ -enriched milk substitute could withstand low pasteurization. • The structure and properties of pH shifted insect protein were characterized.