Antimicrobial Activity of Coriandrum sativum L. and Its Effect on Microbiological Properties of Yoghurt

In this study, the antimicrobial effect of Coriandrum sativum L. leaves against 30 different foodborne microorganisms, including 20 bacteria, 7 fungi, and 3 yeast species was tested, and some microbiological properties of yoghurt produced with lyophilized C. sativum L. were investigated. Yoghurts were prepared at three different concentrations of C. sativum L. powder (0.1, 0.2, and 0.3% w/w) and stored at 4°C for 21 days. Ethanol extract of the fresh plant showed antimicrobial activity against only 9 bacteria and 1 yeast with different inhibition zone diameter changing from 8 to 12 mm, but had no effect on moulds used in this study. The addition of C. sativum L. had no statistical significance on the growth of yoghurt bacteria compared with the control sample and they remained over 8 log CFU g-1 in all yoghurts throught the storage period. On the other hand, an increase was observed in the number of Lactobacillus bulgaricus and a decrease in the number of Streptococcus thermophilus depending on the concentration of C. sativum L., but this was not statistically significant (P> 0.05). However, significant differences in yeast and mould counts were observed (P< 0.05). Yeasts and moulds were not detected in any of the samples containing C. sativum L. powder, whereas the counts of yeast and mould increased in control throught the storage period. These results show that the powder of C. sativum L. leaves can be used an agent for preventing the growth of yeast and mould, which are shelf-life and quality spoilage microorganisms of yoghurt.