Impact of ultrafine bubbles on the survivability of probiotics in fermented milks

Abstract

The impact of three different types of gas (CO2, N2, and N2 + H2) ultrafine bubbles (UFBs) on the survivability of six probiotics (Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus rhamnosus, Streptococcus thermophilus) in fermented milks during 35 days of refrigerated storage was studied. The milks with UFBs were fermented with individual probiotics until pH 5.0 was achieved, stored at ∼4 °C, and analyzed weekly for microbial enumeration and chemical characteristics. This study was designed as a two-factorial (UFB and storage day) randomized complete block design with three replications as blocks. Overall, UFBs did not affect the survivability of probiotics; however, L. rhamnosus population was affected by UFB and storage day, and L. bulgaricus survival was only affected by storage day. Overall, titratable acidity, dissolved oxygen, and redox potential increased, while pH decreased during the storage period.