Raw milk processing by high-intensity ultrasound and conventional heat treatments: Microbial profile by amplicon sequencing and physical stability during storage

Abstract

This study aimed to evaluate the effects of conventional heat treatments (high-temperature–short-time and low-temperature–low-time) and high-intensity ultrasound (HIUS) on the physical stability and bacterial diversity of whole milk during refrigerated storage. HIUS processing used an energy density of 3 kJ/mL and an ultrasound intensity of 90 W/cm2. The most abundant bacterial genera found in raw milk were Acinetobacter and Pseudomonas. After processing and storage for 7 days, Acinetobacter, Kluyvera and Serratia were the dominant genera in almost all samples, and Pseudomonas was the most abundant in HIUS-processed milk. Only the HIUS process reduced the fat droplet size (<1 µm), providing better physical stability during the storage period.