Analysis of the physicochemical properties, texture, and microbial profile of set-type buffalo milk yogurt fortified with zinc oxide micro- and nanoparticles

Zinc oxide (ZnO) nanoparticles are increasingly utilized in various fields due to their distinct properties. This research focused on fortifying buffalo milk with ZnO for yogurt manufacture at concentrations of 3 mg/100 mL for microparticles and 1.5 and 3 mg/100 mL for nanoparticles. Characterization showed ZnO nanoparticles with 61 nm average size and −26.1 mV zeta potential. ZnO-fortified yogurt was evaluated for chemical composition, texture profile, total bacterial counts, and sensory evaluation over 14 days of cold storage. The accumulation of zinc in liver and kidney was in vivo evaluated. The addition of ZnO notably improved yogurt's total solids and texture; 3 mg/100 mL increased stringiness, cohesiveness, and gumminess, whereas 1.5 mg/100 mL raised the hardness, adhesiveness, springiness, and chewiness. Moreover, ZnO fortification was beneficial for the microbial quality, yielding lower bacterial counts than the control. Atomic force microscopy evidenced ZnO uniform distribution within the yogurt matrix. Zinc accumulation in liver and kidney tissues was lower in animal groups fed on ZnO nanoparticles-fortified yogurt than those fed on ZnO microparticles-fortified yogurt. This investigation underscores the comprehensive effects of ZnO fortification on the quality of buffalo milk yogurt, encompassing improvements in composition, texture, microbial quality, sensory evaluation, and potential health implications.