• Phytic acid (PA) content modulated the colloidal stability of peanut milk. • Excessive PA removal induced phase separation and instability. • Whey protein restored stability of PA-free peanut milk. • The dual strategy enhanced protein digestibility and calcium bioaccessibility. Plant-based milk require innovative strategies to overcome inherent limitations in nutritional quality and colloidal stability. This study systematically investigated the effects of phytase-induced phytic acid (PA) removal, whey protein concentrate (WPC) supplementation, and calcium fortification on the physical stability, microstructure and digestive behavior of peanut milk. Results showed that phytase treatment markedly reduced the PA content and the absolute zeta potential of peanut milk, and increased its particle size (from 308.65 nm to 1191.5 nm). The physical stability of peanut milk with completely removed PA is severely compromised, exhibiting pronounced flocculation and stratification during storage. However, the addition of 1.2 wt% WPC to peanut milk by 15 U/g phytase enzymatic treatment resulted in a reduction of the instability index from 0.492 to 0.109, enhancement of the viscoelastic properties, and restoration of the stability compromised by PA removal. The microstructure revealed that WPC adsorbed onto the oil droplet surface and formed a network structure. During in vitro digestion, PA-degraded combined with the WPC supplementation system maintained smaller particle size transitions and more negative surface charge in intestinal fluid, conferring resistance against calcium-induced flocculation. Moreover, this dual-modification strategy elevated protein digestibility and calcium bioaccessibility by 20% and 18.59% relative to native peanut milk, respectively. Although calcium fortification increased the absolute bioaccessible calcium content, a considerable amount of free calcium was lost through the formation of insoluble calcium-fatty acid complexes. This study will provide a guidance for the development of high-nutrient and dual-protein plant-based milk products, enriching the theoretical basis for nutritional fortification in plant-based milk.
Chen et al. (Sun,) studied this question.