Effect of Lemongrass Essential Oil Vapors on Microbial Dynamics and Listeria monocytogenes Survival on Rocket and Melon Stored under Different Packaging Conditions and Temperatures.

Agni Hadjilouka,Melissanthi Polychronopoulou,Periklis Tzamalis,Spiros Paramithiotis,Eleftherios Drosinos

doi:10.3390/microorganisms3030535

Agni Hadjilouka, Melissanthi Polychronopoulou + Show 3 more

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https://doi.org/10.3390/microorganisms3030535

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Journal: Microorganisms	Publication Date: Sep 9, 2015
Citations: 41	License type: CC BY 4.0

Affiliation: Agricultural University of Athens

Abstract

The aim of the present study was to examine the effect of lemongrass essential oil vapors on the dynamics of surface microbiota and L. monocytogenes growth on rocket and melon under different packaging conditions and storage temperature. For that purpose, rocket and melon were placed on Expanded Polystyrene (EPS) trays, sprayed with L. monocytogenes to a population of 4.5–5.0 log CFU·g−1, packaged using microperforated Oriented Polypropylene (OPP) film in either air or Microperforated Active Modified Atmosphere (MAMA) (initial atmosphere 5% O2, 10% CO2) including a Whatman paper containing the essential oil, without contact with the product, and stored at 0, 5, 10, and 15 °C. Application of lemongrass exhibited a bactericidal effect on enterococci and a fungistatic effect on yeast-mould populations but only during air storage of rocket. The former took place at all temperatures and the latter only at 10 and 15 °C. No effect on shelf life of both products was recorded. However, an important effect on the sensorial properties was observed; during the first 4–5 days of storage both products were organoleptically unacceptable. Regarding MAMA packaging, it affected only Pseudomonas spp. population resulting in a reduction of 1–2 log CFU·g−1 in both products.

Highlights

Listeria monocytogenes has been implicated as the causative agent in several foodborne outbreaks after consumption of ready-to-eat fruits and vegetables
Protection of fresh produce against pathogenic microorganisms needs to be carried out through treatments that do not preclude the food from bearing the term “fresh”, which suggests or implies that the food is unprocessed, it is in a raw state and has not been frozen or subjected to any form of thermal processing or any other form of preservation [4]
Among the natural antimicrobials that are used in food industry are the essential oils (EO’s), volatile oily liquids obtained from different plant parts and fruits

Summary

Introduction

Listeria monocytogenes has been implicated as the causative agent in several foodborne outbreaks after consumption of ready-to-eat fruits and vegetables. Contamination of fresh produce is facilitated by the ubiquitous nature of the pathogen as it is widely distributed in soil surface, decaying vegetation, soil sewage, animal feces, river and canal waters, fertilizers, plants, and animals and it is known to survive in plant material for 10–12 years [1] and in soil for up to 295 days [2]. The antimicrobial properties of the essential oils have been known for centuries. They are widely used in food industry as food flavors and numerous studies have described their antimicrobial effects as well as their great importance in several other fields, such as pharmacology and pharmaceutics [6,7,8]

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