Effect of lyoprotectants on β-glucosidase activity and viability of Bifidobacterium infantis after freeze-drying and storage in milk and low pH juices

Abstract

The benefit of disaccharide protectants for maintaining viability and β-glucosidase activity of Bifidobacterium infantis UV16PR during freeze-drying and storage in different food matrices was investigated. Protectants used were cellobiose, lactose, sucrose and trehalose.At 5% concentration, cellobiose showed the best protective effect during freeze-drying. All protectants at 10% concentration significantly improved the viability and retention of β-glucosidase activity after freeze-drying and storage in food matrices. Regardless of the protectant used, no significant differences were observed after freeze-drying and storage for 2 weeks in milk, while in red-beet and grape juice, cellobiose and trehalose significantly enhanced β-glucosidase activity, viability and acid tolerance. Viability of cellobiose and trehalose protected cells in juices was comparable, whereas differences in retention of enzyme activity and acid tolerance after the storage in different juices were observed. In conclusion, various protectants increased the retention of β-glucosidase activity, viability and acid tolerance of freeze-dried B. infantis during storage in different food matrices. In order to choose protectants for probiotics for freeze-drying and food as probiotic carrier, not only their effect on survivability, but also the enzyme activity retention should be considered.