Effect of selected medicinal herbs on viability and acid production of lactic dairy starters

Abstract

Four medicinal herbs viz., Zingiber officinale (Ginger), Asparagus racemosus (Satavari), Chlorophytum borivillianum (Safed Musli) and Withania somnifera (Ashwagandha) were evaluated for their antimicrobial/stimulatory effects on four selected lactic acid bacteria viz., Lactobacillus helveticus MTCC 5463, Lactobacillus rhamnosus MTCC 5462, Streptococcus thermophilus MTCC 5460 and Streptococcus thermophilus MTCC 5461 by cup well assay technique as well as by observing changes in pH, acidity and viable lactic acid bacterial counts in skimmed milk in the presence of medicinal herbs (@1%). Safed Musli and ginger did not show any inhibition to any of the tested lactic cultures. Satavari had shown very little inhibition, while Ashwagandha powder significantly inhibited the growth of all the lactic cultures with maximum effect on Lb. helveticus MTCC 5463. The pH ranged from 4.67 to 5.35, and the percent lactic acid ranged from 0.44 to 0.67. The log viable count ranged from 7.15 to 9.40 in the herbs added fermented milk while control ranged from 8.07 to 9.4. The increase in the log viable count was least in the fermented milk with ashwagandha. The ginger and Safed Musli added milk had either no or least inhibitory effect on viable lactic bacterial count compared to the control during fermentation. However, with culture Streptococcus thermophilus MTCC 5461, the log count was higher in ginger (9.42) and Safed Musli (9.40) added fermented milk as compared to the control (9.38) indicating a supportive role.