Viability of Lactobacillus paracasei in Probiotic Yogurt Containing Green Tea and Green Coffee Powders

This study aimed to investigate the effect of green tea and green coffee powders at 0, 1, and 2% levels, each separately on the viability of Lactobacillus paracasei in probiotic yogurt. The viability of Lactobacillus paracasei was evaluated in terms of microbial count, pH, and sensory evaluation of yogurt samples in three replicates on days 1, 7, 14, and 21. The results showed that the addition of green tea and green coffee powders to probiotic yogurt significantly increased the viability of Lactobacillus paracasei in all samples compared to the control yogurt (p<0.05). The highest number of bacteria in yogurt samples containing 1% green tea and 2% green coffee contained 13.78 ± 0.17 and 11.54 ± 0.2 log CFU/g, respectively. The lowest and the highest pH values belonged to the yogurt sample containing 2% green tea and 2% green coffee, respectively. The best taste was related to the yogurt sample containing 1% green coffee and the most favorable texture and color was related to the control yogurt sample. The highest scores in terms of overall acceptance were in the control yogurt sample, yogurt containing 1% green tea and yogurt containing 1% green coffee, respectively. In conclusion, the results showed that the addition of 1% green tea, had a good effect on the viability of Lactobacillus paracasei and can be used for commercial production.