The Viability of Free and Encapsulated Lactobacillus casei and Bifidobacterium animalis in Chocolate Milk, and Evaluation of Its pH Changes and Sensory Properties during Storage

Aims: The viability of encapsulated and free Lactobacillus casei and Bifidobacterium animalis subsp. lactis bacteria in chocolate milk for the first time as well as the influence of the bacteria on acidification and sensory acceptability of the product at 5°C for 21 days.

Study Design: Research study

Place and Duration of Study: Department of Public Health, Maragheh University of Medical Sciences, between October 2016 and April 2017.

Methodology: The Lactobacillus casei and Bifidobacterium animalis subsp. Lactis were injected into chocolate milk in free and microencapsulated forms. Sodium alginate plus resistant starch and sodium alginate plus chitosan were used via extrusion method for microencapsulation. The changes in probiotic bacteria count and their sensory acceptability were evaluated at 5°C for 21 days.

Results: The chocolate milk containing microencapsulated bacteria had a slight decrease in pH compared with the products with free bacteria. Further, the rate of microencapsulated bacteria viability was high in comparison with free bacteria in all conditions (p<0.05). Also, a product with microencapsulated bacteria has a more desirable sensory properties compared with a product with free bacteria at 5°C for 21 days; hence, it has a higher acceptability.

Conclusion: Probiotic bacteria microencapsulation in the chocolate milk, as well as low temperature storage, can increase the viability of probiotics into product and postpone the fermentation process in chocolate milk. Based on the sensory evaluations and total acceptability scores, the chocolate milk containing microencapsulated Lactobacillus casei with an expiration of 6 days and containing Bifidobacterium animalis with an expiration of 10 days can be produced.