Growth Potential of Listeria monocytogenes on Cantaloupe (cucumis melo) pulp evaluation under a dynamic time-temperature profile

Ortali, Arianna and Onarinde, Bukola (2021) Growth Potential of Listeria monocytogenes on Cantaloupe (cucumis melo) pulp evaluation under a dynamic time-temperature profile. In: ASM Microbe 2021, 20 - 24 June 2021, Online.

Documents
Growth Potential of Listeria monocytogenes on Cantaloupe (cucumis melo) pulp evaluation under a dynamic time-temperature profile
Conference poster
[img]
[Download]
[img]
Preview
PDF
iPoster Gallery - Cantaloupe.pdf - Whole Document

1MB
Item Type:Conference or Workshop contribution (Poster)
Item Status:Live Archive

Abstract

Background: Although ready-to-eat (RTE) fruits and vegetables are a healthy and convenience food choice, they have in most recent years been associated with several foodborne outbreaks. Several bacteria pathogens have been implicated in such outbreaks however Listeria monocytogenes is reported to have a higher case-fatality rate compared to Salmonella and Escherichia coli. A recent case that was reported involving Listeria was relating to consumption of contaminated cantaloupe which led to the death of two people. Listeria is ubiquitous in the environment, hence contamination of fresh produce such as melons could occur in field where the outer rind of melons, especially the irregular rough rind of cantaloupe, aids the adhesion of soil and microorganisms. Also, storage period and temperature are important factors influencing the growth and survival of L. monocytogenes in foods such as RTE fruits. While temperature is not always guaranteed during cold chain, growth potential (the difference between the final and initial counts) (δ) could be an instrument to evaluate the storage conditions that can be most suitable for controlling level of L. monocytogenes in fruits. The aim of this study was to evaluate the influence temperature has on the Growth Potential (δ) of L. monocytogenes during a simulation of real cold chain scenario. Method: L. monocytogenes was prepared by inoculating L. monocytogenes culture in in freshly prepared TSB (Tryptic Soy Broth), incubated overnight at 37°C in agitation, followed by centrifugation and washing with 0.1% of peptone. Cantaloupe was cut into cubes of 10g and inoculated with 10 µl of L. monocytogenes inoculum. Results: The initial level of L. monocytogenes was 5.7 Log CFU/g. Two time-temperature scenarios (4°C for 24 h then 8°C or 12°C for 48h) were assessed and the trial was repeated three times. The average δ after 24h at 4°C resulted 0, 0.9 after only 24h at 8°C and 1 after 48h. The δ after 24h at 12°C resulted 1.6 and 1.7 after 48h. Growth potential δ of >0.5 Log means a food cannot support the growth of Listeria. Conclusion: The results show that the temperature has a fundamental impact on δ. Indeed, in only 24h of abuse of temperature the δ increased by 1 point changing the denomination of the product from non-supporting to supporting the growth of Listeria. The temperatures applied in the trial are commonly detected in the real life, especially in the final stages of cold chain (retail and household).

Keywords:Growth potential, Listeria monotocytogenes, Cucumis melo, Time-temperature
Subjects:C Biological Sciences > C510 Applied Microbiology
C Biological Sciences > C500 Microbiology
Divisions:College of Science > National Centre for Food Manufacturing
ID Code:46086
Deposited On:22 Sep 2021 09:32

Repository Staff Only: item control page