Vol. 12, Special Issue 11 (2023)

Author(s):
Shreya Talan, Pushpalatha K and Dr. Raghu HV

Abstract:
The present study was set out to determine the frequency of Listeria monocytogenes in milk. “Two stage enzyme assay for detection of L. monocytogenes in milk and milk products” developed at ICAR-NDRI, Karnal was used to analyse a total of 70 samples, 35 of which were each of raw and pasteurized milk. For further assurance, ISO 11290-1:2017 was also used to validate the results. One raw milk sample tested positive for L. monocytogenes during the assay examination, a finding that was corroborated by the traditional approach as well. The principle of the assay is colorimetric reaction due to enzyme substrate interaction. The LOD of the developed assay is 1.0 ±0.5 log cfu/25 ml for milk. The detection time taken by developed assay for L. monocytogenes and Listeria spp. is 4.30±0.15 hours and 2.30±0.15 hours respectively after pre enrichment for 24±1 hours. The determining duration of the developed assay is much less compared to the traditional method which takes 5 days to a week for validation. The results obtained by the developed assay were rapid and had the same accuracy as that of conventional method thus, indicating the wide scope for its application in dairy and food products.