Turbidimetric Assay of Nisin in Tender Coconut Water

Nisin activity in tender coconut water using Lactococcus lactis subspecies cremoris as test microorganism was estimated using turbidimetry by measuring optical density at 600nm after 6 h. of incubation at 37 0 C. The test microorganism was cultivated in nutrient broth with different concentration of nisin along with tender coconut water. A standard curve was drawn between optical density and known concentration of nisin. The nisin concentration of the test samples was measured by curve fitting method using the optical density values. The results thus obtained by this method were reproducible, rapid and more accurate in tender coconut water and hence it may be employed for the determination of nisin activity in tender coconut water on regular basis for quality control purposes.