Enhancement of viability of a probiotic Lactobacillus strain for poultry during freeze-drying and storage using the response surface methodology.
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 X(1)-0.09382 X(2)-0.07771 X(3)-0.054861 X(1)(2)-0.04603 X(3)(2)-0.10938 X(1)X(2). 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.
Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Selangor Darul Ehsan, Malaysia.
Anahita
A
Khoramnia
Norhani
N
Abdullah
Siew Ling
SL
Liew
Chin Chin
CC
Sieo
Kalavathy
K
Ramasamy
Yin Wan
YW
Ho
D000818:Animals; D001431:Bacteriological Techniques; D002470:Cell Survival; D002645:Chickens / Q000382:microbiology*; D003451:Cryoprotective Agents; D005612:Freeze Drying; D052200:Limosilactobacillus reuteri; D007785:Lactose; D008892:Milk; D019936:Probiotics; D013395:Sucrose; D013696:Temperature; D013997:Time Factors
D003451:Cryoprotective Agents; D013395:Sucrose; D007785:Lactose