Old curd is rich in probiotics

Experimentation and written by pankaj chhabra in December 2008

Objective

To study antibacterial activity (in vitro) of Fresh and sour dahi collected from Rishikesh (Uttarakhand).

Methodology—

Collection of samples

10 fresh homemade curd samples from different dairy shops of Rishikesh were collected in autoclaved (for 15 min) culture test tubes . Half amount of each fresh sample was centrifuged, filtered and supernatant was obtained, filtering through Millex-GV filter (.22 mm pore size Millipore). Samples were stored at -20⁰C until measurement of antibacterial activity. Supernatant of other half was obtained after 3^rd day of storage at refrigeration tempt and analyzed for antibacterial activity.

Measurements of antibacterial activity

Staphylococcus aureus (MTCC 96), E.coli (MTCC 119), Shigella sonai (MTCC 2957) were procured from IMTECH, Chandigarh and sub cultured on nutrient broth media at 37⁰C for 24 hour. Autoclaved petri dishes were prepared for nutrient agar media. Antibacterial activity of supernatant was measured by using well diffusion agar assay (Tag &Mc Given,1971 ).

Results and Discussion

Inhibitory spectrum of supernatant of fresh curd was measured against staphylococcus aureus, E.coli, Shigella sonai as 12 mm, Nil and 11 mm respectively while of old (sour) curd was 18 mm, 12 mm, 20 mm respectively. Reason could be old curd contains more LAB responsible for bacteriocin production.