Bifidobacteria are probiotic organisms that improve the microbial balance in the human gut. They can be incorporated as live cultures in fermented dairy foods, including yogurt, for transmission to humans. Because bifidobacteria are sensitive to high acidity, their viabil- ity in yogurt is limited. The objective of the present study was to investigate the effect of microencapsula- tion on the viability of bifidobacteria in yogurt during refrigerated storage for 30 d. Live bifidobacterial cells were encapsulated in κ-carrageenan. Cell enumeration, determination of titratable acidity and pH, quantita- tion of lactic and acetic acids, and sensory evaluation (consumer test) were carried out on the yogurt samples. Microbiological results showed a decline of 78 and
70.5% in the population of Bifidobacterium longum B6 and B. longum ATCC 15708, respectively, for the treat- ments containing nonencapsulated cells. No difference in bifidobacterial population was observed in the encap- sulated treatments. The acetic acid content in the yo- gurt with nonencapsulated bifidobacteria was higher than that in the plain yogurt (control) and encapsulated treatments. The increase in lactic acid content during storage was not different among the various treatments for B. longum B6, but was greater for nonencapsulated than encapsulated B. longum 15708 and the control. Consumers judged the nonencapsulated treatment as the most sour, which was likely due to the higher acetic acid content. Consumers preferred the control and non- encapsulated treatments over the encapsulated treat- ment. Microencapsulation appears to increase the via- bility of bifidobacteria in yogurt. This technique can be used to transmit bifidobacteria via fermented products provided that sensory characteristics of the product are improved or maintained.