Enhancement of probiotics viability and lactic acid production in yogurts treated with Prangos ferulaceae and Carum copticum plant extracts

Abstract This study aimed to investigate the effects of two plant extracts, Prangos ferulaceae, and Carum copticum, on the growth and survival of Lactobacillus plantarum and Bifidobacterium animalis subsp. lactis strains in 4 types of yogurt prepared using milk of cow, sheep, goat, and camel. The conditions of the yogurt probiotics were evaluated through the colony count method after 0, 7, 14, and 21 days with the lactic acid produced in each sample assessed using gas chromatography analysis after 21 days. The sensory characteristics of different yogurts were evaluated 7 days after production. We also examined the effect of casein and whey protein derived from four mentioned milk on the growth of probiotic bacteria in MRS agar medium. According to the results, the presence of both extracts significantly enhanced the survival of probiotics in each yogurt. The sheep yogurt treated with Prangos ferulaceae contained 9.7 log CFU/mL of Lactobacillus plantarum. Further, the lactic acid content of all samples was considerably higher than the controls. Also, Prangos ferulaceae could raise the lactic acid generated by Lactobacillus plantarum to more than 5 g/L of sheep yogurt. Notably, whey protein derived from sheep milk had the most positive effect on the growth of the mentioned bacteria. On the other hand, bovine casein showed a significant effect on decrease in growth of probiotics bacteria. The sensory analysis also determined that the yogurt samples supplemented with Prangos ferulaceae were more preferable than plain yogurt samples.