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Abstract
A total of one hundred and twenty samples of meat and poultry products including chicken shawerma, chicken nuggets, meat shawerma and Burghol kobiba were collected randomly from the supermarkets in Gharbia governorates and transferred in an ice box as soon as possible to the laboratory to be examined.
Samples were examined for the presence of Listeria monocytogenes and other Listeria species. Isolation of these pathogen was conducted by the USDA-FSIS technique, by using two enrichment media (UVM I and UVM II) followed by isolation in PALCAM agar. The suspected positive colonies were then confirmed by several biochemical tests.
L.monocytogenes was isolated from 1.6% of meat product samples only from Burghol kobiba and from 11.6% of poultry product samples, while other Listeria species were detected only in poultry product samples in an incidence of 68.3%.
L.monocytogenes was isolated from 3.3% of Burghol kobiba, 16.7% of Chicken shawerma and 6.7% of Nuggets; while it failed to be detected in meat shawerma samples.
The present study revealed that Listeria spp. failed to be detected in the examined meat shawerma and Burghol kobiba samples; while L.ivanovii, L.innocua, L.welshmeri, L.seeligeri and L.grayi were isolated in a percentage of 20%, 10%, 16.6%, 6.6% and 10%, respectively from the examined chicken shawerma samples.
In this study, examination of chicken nuggets revealed that L.innocua, L.welshmeri and L.grayi were detected in 26.6%, 30% and 16.6%, respectively. L.murrayi failed to be detected in the examined poultry product samples.
from these results it is concluded that chicken shawerma is highly contaminated with all Listeria species followed by chicken nuggets, while meat products were less contaminated. Sterile chicken shawerma was used as a model, Nisaplin® (2.5% nisin) was added in two concentrations 100 and 500 p.p.m and examined in day 0, 7th and 14th to examine the L.monocytogenes count. So, addition of bacteriocin as Nisaplin® (2.5% nisin) in different concentration (100-500 p.p.m) was used in controlling Listerial growth in these products.
Nisaplin® (2.5% nisin) in 100 p.p.m concentration has antilisterial effect as it decreased the number of inoculated L.monocytogenes from 1×108 to 2.36×107 Then to 4.46×106 by the time periods.
While at 500 p.p.m concentration it has a more powerful and fast antilisterial effect as it decreased the numbers of L.monocytogenes from 1×108 to 9.00×106 then to1.23×106 by time periods.