Enhancement of viability of a probiotic Lactobacillus strain for poultry during freeze‐drying and storage using the response surface methodology |
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| Authors: | Anahita KHORAMNIA Norhani ABDULLAH Siew Ling LIEW Chin Chin SIEO Kalavathy RAMASAMY Yin Wan HO |
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| Institution: | 1. Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences,;2. Institute of Bioscience, Universiti Putra Malaysia,;3. Faculty of Science and Technology, Universiti Kebangsaan Malaysia,;4. Faculty of Pharmacy, Universiti Teknologi MARA Malaysia, Selangor Darul Ehsan, Malaysia |
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| Abstract: | A rotatable central composite design (CCD) was used to study the effect of cryoprotectants (skim milk, sucrose and lactose) on the survival rate of a probiotic Lactobacillus strain, L. reuteri C10, for poultry, during freeze‐drying and storage. Using response surface methodology, a quadratic polynomial equation was obtained for response value by multiple regression analyses: Y = 8.59546 ? 0.01038 X1 ? 0.09382 X2 ? 0.07771 X3 ? 0.054861 X12 ? 0.04603X32 ? 0.10938 X1X2. Based on the model predicted, sucrose exerted the strongest effect on the survival rate. At various combinations of cryoprotectants, the viability loss of the cells after freeze‐drying was reduced from 1.65 log colony forming units (CFU)/mL to 0.26–0.66 log CFU/mL. The estimated optimum combination for enhancing the survival rate of L. reuteri C10 was 19.5% skim milk, 1% sucrose and 9% lactose. Verification experiments confirmed the validity of the predicted model. The storage life of freeze‐dried L. reuteri C10 was markedly improved when cryoprotectants were used. At optimum combination of the cryoprotectants, the survival rates of freeze‐dried L. reuteri C10 stored at 4°C and 30°C for 6 months were 96.4% and 73.8%, respectively. Total viability loss of cells which were not protected by cryoprotectants occurred after 12 and 8 weeks of storage at 4°C and 30°C, respectively. |
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| Keywords: | cryoprotectants freeze‐drying probiotic response surface methodology storage |
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