Conventional heating, ultrasound and microwave treatments of milk: Fermentation efficiency and biological activities

The individual and combined effects of ultrasound, microwave, and heat treatment of milk on L. acidophilus viability, lactate concentration and bioactive properties (radical scavenging capacity, proteases activities, peptide level, anticancer activity, α-amylase inhibition and exopolysaccharide content) during fermentation were investigated. It was notable that Lactobacillus acidophilus exhibited by far the best growth in microwave treated samples, while ultrasonicated microwaved samples had higher antioxidant and anticancer activities. The antioxidant activity of ultrasonicated microwaved milk at the end of fermentation was 13.9%, 44.7% and 77.3% higher than that of ultrasonicated autoclaved, microwaved and autoclaved samples, respectively. After 24 h fermentation, the average protease activity of the microwaved milk was 1.3–1.8 times more than the observed values in the other treated samples. The amount of exopolysaccharide, anticancer activity and α-amylase inhibition of ultrasonicated microwaved milk, especially after 8 h fermentation, were also significantly higher than those of the other treated milks.