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ARPN Journal of Science and Technology >> Volume 7, Issue 2, November 2017

ARPN Journal of Science and Technology

Effect of Freeze - Drying on Viability and Probiotic Properties of a Mixture of Probiotic Bacteria

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Author R. M. U. S. K. Rathnayaka
ISSN 2225-7217
On Pages 1074-1078
Volume No. 3
Issue No. 11
Issue Date December 01, 2013
Publishing Date December 01, 2013
Keywords Probiotic cultures, Cryoprotectants, Freeze drying.


The effect of freeze drying on viability and probiotic properties of a probiotic microbial mixture containing Lactobacillus rhamnosus and L. plantarum was studied. Ability of UHT milk, sucrose, sorbitol and trehalose to protect viability and probiotic properties of freeze dried microbial mixture during six month storage at 4 0C was also studied. Five types of mixed probiotic cultures were prepared as microbial mixture in PBS, UHT milk, UHT milk added with sucrose, UHT milk added with sorbitol and UHT milk added with trehalose. Those were freeze dried and stored at 4 0C for six months. Immediately after freeze drying and at day 30, 60, 90, 120 and 180 during storage, those microbial mixtures were tested for viability and probiotic properties. Enumeration of samples taken from cultures in MRS agar media and Shigella inhibitory assay was used for the testing of viability and probiotic properties respectively. Better survival of microorganisms after freeze drying was shown in all tested microbial mixtures except the microbial mixture in PBS. Highest microbial survival was shown in the microbial mixture UHT milk. Addition of other cryoprtectant sucrose, sorbitol and trehalose did not improve the microbial survival than UHT milk alone. Hence, addition of those to UHT milk was found ineffective. According to the results of Shigella inhibitory assay, probiotic properties of microbes has not been changed by freeze drying or long term storage. Freeze drying can be used for preservation of tested probiotic cultures in UHT milk without any significant effect to its viability and probiotic properties.

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