Thesis
Impact of ultrafine bubbles on the survivability of probiotics in fermented milks
Washington State University
Master of Science (MS), Washington State University
2022
DOI:
https://doi.org/10.7273/000005130
Abstract
Probiotics of fermented milks have been reported to confer health benefits to the host. However, probiotics tend to lose their viability during the storage of fermented milk products. This study hypothesized that the presence of ultrafine bubbles (UFBs) can increase the viability of probiotics in fermented milks by reducing the redox potential and dissolved oxygen content. The effect of three different types of gas UFBs (CO2, N2, & N2+H2) on the survivability of six probiotics in fermented milks stored at 5 ˚C for 35 days was investigated. The UFBs were prepared by passing milk through a micro-nanobubble generator and then inoculated with individual probiotics. Milks were incubated at 37 ˚C with the endpoint of fermentation at a pH of 5.0. Microbial and chemical analyses of Eh, pH, dissolved oxygen, and titratable acidity of samples stored at 4 ˚C were conducted weekly from day 0 to 35. The study was designed as a two-factorial (storage day and UFB type) randomized complete block design with three replications as blocks. The mean surviving bacterial population (log CFU mL-1), pH, Eh, and titratable acidity for each probiotic culture during storage were compared at P ≤ 0.05 through two-way ANOVA and Tukey’s test using Minitab® 19 (Minitab Inc., State College, PA). Storage days and UFB type had a significant effect on the survival of Lactobacillus rhamnosus. In contrast, Lactobacillus bulgaricus survival was affected by storage days. The UFBs did not increase the survivability of B. animalis, L. acidophilus, L. casei, and S. thermophilus. Depending upon titratable acidity, dissolved oxygen, and redox potential increased, while pH decreased during the storage period. The non-significant effect of UFBs on probiotics survivability was attributed to the high pH of the endpoint of fermentation. Future work will test the effects of UFBs in < 4.6 pH fermented dairy products.
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Details
- Title
- Impact of ultrafine bubbles on the survivability of probiotics in fermented milks
- Creators
- Sonali Sharma
- Contributors
- Minto Michael (Advisor)Girish Ganjyal (Committee Member)Thuy Bernhard (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 90
- Identifiers
- 99901019639101842
- Language
- English
- Resource Type
- Thesis