Investigating the effect of aqueous extracts of basil and savory on antioxidant activity, microbial and sensory properties of probiotic yogurt.

Background: The low viability of probiotics causes the short shelf life of fermented products. Therefore compounds which prolong the viability of probiotic bacteria can increase or at least maintain the health- benefiting properties of these products. On the other hand, the addition of antioxidants is one of the methods to increase the shelf life of food products which has recently become more prevalent. In this respect, herbal extracts which are a good source of antioxidants can be appropriate alternative. The aim of this study was  to evaluate the effect of adding basil and savory extracts on antioxidant activity, and on the microbial and organoleptic characteristics of probiotic yogurt.

Methods: The effect of adding basil extract (8% and 10%) and savory extract (6% and 8%) separately to low fat yogurt (1.5% fat) containing Lactobacillus paracasei subsp. paracasei was investigated. The samples were stored at 4°C. The viability of Lactobacillus paracasei subsp. paracasei, antioxidant activ- ity and sensory properties of probiotic yogurt were evaluated on the 1st, 7th, 14th and 21st days.

Results: Basil and savory extracts significantly increased the viability of probiotic bacteria (p < 0.05). Dur- ing storage, probiotic counts markedly decreased (p < 0.05) in comparison to the control sample. The addi- tion of herbal extracts significantly increased antioxidant activity, but this activity decreased during storage (p < 0.05). The scores for taste, odor, color and overall acceptance decreased as herbal extracts increased, but there was no significant difference between the test samples and control sample in terms of the texture score (p > 0.05). During storage, there was no significant difference between the organoleptic scores of the samples (p > 0.05), but the taste score did increase significantly (p < 0.05).

Conclusions: It can be concluded that adding herbal extracts had a positive effect on the viability of probiotics and antioxidant activity of probiotic yogurt.