Survival and shelf life of Lactobacillus lactis 1464 in shrimp feed pellet after fluidized bed drying

In the present study, Lactobacillus lactis 1464 was attempted to be incorporated in shrimp feed pellets. The fresh culture (25% volume per weight) with and without pH adjustment was mixed into feed ingredients prior to the pelleting process at ambient temperature. The wet pellets were dried using a fluidized bed dryer at 50 °C, 60 °C, 70 °C and 80 °C to achieve a moisture content below 11%. The results indicated that the strain viability depended on the drying temperature with a viable cell number of approximately 106−108 CFU/g and the pH of the culture was found to affect the strain viability during drying. At all drying temperatures, the strain survival after drying ranged from 75.94% to 92.28% at pH 3.8 and from 89.54% to 96.87% at pH 7.0. Moreover, the addition of protectants was found to enhance the strain survival during drying. In particular, milk powder and monosodium glutamate (MSG) exhibited significant (p < 0.05) protective effect on the viability at a high temperature of 80 °C. During storage at 30 °C, a high survival rate was found for the strain with MSG and acacia gum. Furthermore, the prediction model for long-term storage stability of the strain was found to validate only at a low temperature of 4 °C, in comparison to a high temperature of 30 °C.