Encapsulation of Lactobacillus Acidophilus in a Pilot-Plant Spray-Dryer. Effect of Process Parameters on Cell Viability

Abstract

Encapsulation is a practical technique for the preservation of probiotic cultures. This may be accomplished by spray-drying, even at large scales. The effect of process parameters such as feed rate and pectin concentration in the feed suspension, on cell viability and stability of encapsulated bacteria was studied. Physical characteristics of the dry powder after the drying process were determined in order to evaluate its influence on product stability and viability during 90 days. The studied parameters showed significant influence on the response variables. Process conditions that generated the highest cell viability after spray-drying are not the same as the conditions that caused the highest stability and viability after 90 days of storage. Water activity of the dry powder played a fundamental role in the stability of encapsulated bacteria. This indicates the most suitable operating conditions for the production of encapsulated lactic acid cultures in a pilot-plant spray-dryer. Practical Applications: The retention of viability during processing and storage of probiotic cultures is one of the most challenging problems of biotechnology and food industry. Spray-drying is a useful and economical technology to obtain encapsulated probiotic. The knowledge of the optimal encapsulating matrix and operating conditions of the pilot-plant spray-drying process allows to obtain probiotic cultures with high viability and stability. The combination of pectin and reconstituted skim milk improves bacteria protection due to the reinforcement of the structure resulting from the interaction between the components of both materials. It was found that the operational conditions that produce the highest cell viability after the drying process are not the same that conduct to the highest stability and viability after 90 days of storage. With this information, the most suitable operating conditions for a pilot-plant spray-drying can be defined.