To investigate the effects of tagatose added to yogurt fermented with Streptococcus thermophiles (ST) or Lactobacillus delbrueckii subsp. Bulgaricus (LB), pH, titratable acidity (TA), sugar content, color value, viable cell number, and sensory evaluation were determined on yogurts added with 7% sucrose, tagatose, or a mixture of sucrose and tagatose in triplicate. After 24 h, pH and sugar content of sucrose-added yogurt reached nearly 4.5 and 4.2 respectively, and were lower than those of yogurt with tagatose (above 5.6 and 8.6, respectively). Also, TA of sucroseadded yogurt (1.51%) was much higher than that of yogurt with tagatose (0.59%). There were no significant differences in color value and viable cell count after 24 h. However, the addition of tagatose seems to slow the growth rate of LB more than that of ST. Sensory preference revealed that mixture-added yogurts scored significantly higher in taste (5.90), texture (5.86), and overall acceptability (6.16) than yogurts with tagatose (5.20, 5.02, and 5.36, respectively), but there was no significant difference from the sucrose-added yogurts. In conclusion, tagatose inhibited the fermentation rate, but the mixture of tagatose and sucrose could be used for yogurts with lower calories and glucose index (GI) without a sensory difference from sucrose-added yogurt.

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• 성동은(동양미래대학교 식품공학과) | Dong-Eun Sung (Department of Food Science and Engineering, Dongyang Mirae University)
• 임승용(국립군산대학교 식품생명공학과) | Seung-Yong Lim (Department of Food Science and Biotechnology, Kunsan National University) Corresponding author