Extraction of protein from churpi of yak milk origin: Size reduction, nutraceutical potential and as a wall material for resveratrol

Resveratrol is a known anti-oxidant and anti-cancer bioactive. The low bioavailability and poor water solubility of resveratrol is a major barrier that restricts its usage in food applications. To overcome these problems, the study presents micro and nano encapsulation of resveratrol in casein micelles extracted from Himalayan cheese (Churpi). Resveratrol loaded casein microparticles (CS-rm) were obtained using emulsion-freeze drying. Whereas, resveratrol loaded casein nanoparticles (CS-rn) were obtained using ultrasonication. Both were characterized using dynamic light scattering (DLS), scanning electron microscopy (SEM) and attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR). DLS revealed hydrodynamic diameter of 71.24 μm and 387.023 nm and zeta potential of −22.62 and −28.08 mV for CS-rm and CS-rn. FTIR confirmed the characteristic peaks of resveratrol at 965.4, 1380.86, 1586.66 and 1607 cm−1 confirmed successful micro and nanoencapsulation. CS-rm displayed high encapsulation efficiency (52.32%) and swelling power (77.90 at pH 3 and 68.65 at pH 7.5) than CS-rn. Both micro and nanoencapsulation protected resveratrol in gastric conditions, however, CS-rn showed high release of resveratrol then CS-rm in simulated intestinal conditions. The anti-oxidant and anti-cancer activity of resveratrol under simulated gastric and intestinal conditions (SGID) was significantly higher (p ≤ 0.05) for CS-rn, showing that nanoencapsulation improved release and nutraceutical profile of resveratrol. Resveratrol loaded nano and micro casein particles can be used a source of fortified protein supplement in growing food and nutraceutical industry.