Nano reduction coupled with encapsulation as a novel technique for utilising millet proteins as future foods

Crocin (saffron bioactive) loaded protein nanoparticles were prepared from three underutilised cereal varieties viz., sorghum (SPCN), foxtail millet (FPCN) and pearl millet (PPCN) using ultrasonication technique. The particle size of crocin loaded protein complex was attained in the nano range with reduced polydispersity index and negative zeta potential. The encapsulation efficiency of crocin in protein nanoparticles was found to be 83.78% (FPCN), 78.74 % (SPCN) and 70.01% (PPCN). The topographical images of crocin loaded protein nano complex was revealed using field emission-scanning electron microscopy (FE-SEM). The attenuated total reflectance fourier transform infra-spectroscopy (ATR-FTIR) analysis showed the characteristic peaks of crocin at 956, 1700 and 3350 cm^-1 in protein-crocin nanocomplex as a confirmatory test for nanoencapsulation. The antimicrobial activity of crocin loaded protein nanocomplex against three strains (Escherichia coli, Staphylococcus aureus and Fusarium oxysporium) were also evaluated. In vitro release studies showed higher content of crocin released in simulated intestinal conditions ensuring its controlled release at target site. Bioactivity (anti-cancerous and anti-hypertensive) of crocin upon in-vitro digestion were well retained indicating that protein nanoparticles can act as an effective wall material. Our results suggest that protein nanoparticles prepared in this study can act as an effective oral delivery vehicle for crocin that could be used for development of functional foods.