ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Jayanth Sunderraj Hampapura1,2 and Varadaraj Mandyam Chakravarathy1
1Department of Microbiology and Fermentation Technology, CSIR-Central Food Technological Research Institute, Mysuru-570 020, Karnataka, India.
2Department of Microbiology, Yuvaraja’s College, University of Mysore, Mysuru-570 005, Karnataka, India.
J Pure Appl Microbiol. 2021;15(4):2209-2228 | Article Number: 7240
https://doi.org/10.22207/JPAM.15.4.44 | © The Author(s). 2021
Received: 12/08/2021 | Accepted: 19/10/2021 | Published: 03/11/2021
Abstract

The present investigation assesses the influence of cultural attributes and heat and cold treatments on the behaviour of native toxigenic L. monocytogenes CFR 1302 and non-toxigenic L. innocua CFR 1304 in selected medium. The growth responses of L. monocytogenes and L. innocua under the influencing factors of storage temperature (10-40°C), pH level (5.5-7.5), and storage period (6-48 h) in brain heart infusion and nutrient broths revealed closeness between observed and predicted populations. Response surface plots were generated for the growth behavior of the two test cultures as a function of pH level. The toxigenic L. monocytogenes CFR 1302 could reach a higher viable population. The effect of heat treatment on Listeria spp. in selected five heating menstra showed the lowest D-value of 3.7 min at 60°C for L. innocua CFR 1304 in Milli-Q water to the highest of 8.4 min at 56°C for L. monocytogenes CFR 1302 in skim milk. The average z-value across the heating menstra for L. monocytogenes was 27.3°C as against that of 22°C for L. innocua. In the case of cold treatment, storage of 4 and 8°C resulted in appreciable increase in counts of L. monocytogenes CFR 1302 from the initial inoculum introduced in selected media. At -20°C, there was a slight decrease in the viable population. The research data helps to predict the viable populations of L. monocytogenes as a part of risk assessment in the food chain. This is of significance in providing safe and healthy food to human population.

Keywords

Listeria monocytogenes, Listeria innocua, Growth responses, Influencing factors, Response surface plots, Heat treatment, Cold treatment, D-value

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