Comparative assessment of high-intensity ultrasound and hydrodynamic cavitation processing on physico-chemical properties and microbial inactivation of peanut milk.

Ultra-sonication (US) at varying intensities (200 W, 300 W and 400 W) and hydrodynamic cavitation (HC) at increasing pressures (6 bar, 8 bar and 10 bar) on freshly extracted peanut milk as non-thermal processing of milk for enhanced quality. The effects of US and HC was investigated on physico-chemical properties of peanut milk, microbial inactivation (total plate count and yeasts and molds), microstructure by optical microscopy and particle size, ζ-potential, sedimentation index, rheology and color measurements. The high temperature short time (HTST) treated milk samples have shown 1.53 and 2 log reduction in TPC, yeast and molds respectively with highest protein hydrolysis of 15.7%. Among the non-thermal treatments HC has shown highest log reduction of TPC at around 1.2 for sample treated at 10 bar pressure, whereas the US treatment was most effective for yeast and mold at 400 W with log reduction of 0.9. A non-Newtonian flow behaviour was observed for all peanut milk samples. Viscosity determined by Herschel-Bulkley equation decreased significantly (p > 0.05) after both cavitation treatments. The US was found to be superior to HC and HTST with improved separation index and colour attributes. Therefore, the US and HC appear to be a remarkable non-thermal processing methods for peanut milk and or any dairy or non-dairy beverages.