Development of Sustainable Vegan Pea Protein-Zinc Complex: Characterization, in Vitro Cellular Mineral Uptake, and Application in Functional Biscuit Production

This study aimed to investigate the potential of pea protein concentrate (PPC) to form protein-mineral composites, with a specific focus on its zinc- (Zn-) binding capabilities. In addition, the physical and functional properties of PPC were evaluated. PPC, a potential protein source, was found to possess lipophilic properties, suggesting its suitability for various applications in food production. The investigation involved a comprehensive characterization of pea protein concentrate-zinc complex (PPC-Zn) composites, utilizing various analytical techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, particle size analysis, zeta potential measurement, and thermogravimetric analysis. The findings of this study indicated that the protein content of PPC-Zn (79.02 ± 1.33%) insignificantly increased as compared to PPC (78.86 ± 1.16%). Furthermore, PPC demonstrated improved functional properties, including increased protein solubility (2.55%), enhanced water-holding (13.09%) and oil-holding capacity (11.17%), and improved foaming capacity and stability (2.08% and 6.07%, respectively). These improvements in functional properties were likely attributed to the unique surface structure observed in SEM micrographs. The research also highlighted the maximum binding capacity of PPC for zinc, which was observed at concentrations of 5 mM (95.35 ± 1.86%). This binding of zinc ions to PPC induced changes in the characteristics and internal structures of the protein concentrate. Notably, the presence of functional groups such as -COOH, -OH, and -NH2 in PPC suggested their involvement in coordinating with zinc ions to form PPC-Zn composites. This investigation demonstrated a significant increase (2.26%) in the mineral bioavailability of PPC-Zn. Additionally, the cellular uptake, retention, and transport of PPC-Zn were improved by 9.79%, 7.84%, and 9.51%, respectively. Fortified biscuits (B2) demonstrated enhanced cellular uptake (2.79%), retention (4.84%), and transport (3.51%) compared with control biscuits. Fortified biscuits (B2) had higher microbial counts (total plate count is 3.57 ± 0.03 and the yeast-mold count is 3.96 ± 0.07 cfu/g) than control biscuits (B1) (total plate count is 2.49 ± 0.13 and the yeast-mold count is 3.44 ± 0.11 cfu/g) at the end of storage, and there is no difference in sensory evaluation between the control and fortified biscuits. Furthermore, the key findings indicated that PPC could serve as a promising carrier for mineral supplements, binding with zinc effectively.