MICROBIOLOGICAL QUALITY ASSESSMENT OF DUCK EGG PRODUCTION CHAIN
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Date
2011
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES-MANNUTHY,THRISSUR
Abstract
In the present study the microbiological quality of duck eggs in the production
chain in the University poultry farm, Mannuthy, from six different points of processing,
during pre monsoon (A) and post monsoon (B) season was evaluated. Aerobic Plate
Count (APC), Coliform Count (CC), Escherichia Coli Count (EC) and Yeast and Mould
Counts (YMC) along with isolation of Salmonella spp, Escherichia coli, Bacillus
cereus, Staphylococcus aureus and Listeria monocytogenes were used for assessing
microbiological quality of eggs. The air, water, feed, litter, wash water, cloth used in
washing eggs, hands of workers and environmental parameters in both seasons were
also evaluated to identify the critical contamination points and rectify them. The
microbiological quality of duck eggs available in retail outlet in two seasons was
evaluated and compared with quality of eggs produced from the farm. Chitosan as an
egg paint at 0.5 per cent and 1 per cent concentration was used to evaluate its effect on
microbiological, internal keeping quality and shelf life at refrigeration (40C) and room
temperature (280C). Effect of chitosan (0.5 per cent) as a disinfectant in egg washing
was compared with KohrsolinTM 0.5 per cent and Huwa San at 0.5 per cent.
The counts at the point of lay were highest in both seasons. Counts in season B
were higher than season A. Washing of eggs significantly reduced the counts. Sales
counter showed high E.coli count during season A. Foodborne pathogens like
Escherichia coli, Bacillus cereus, Staphylococcus aureus and Salmonella spp, isolated
revealed high sensitivity to chloramphenicol and third generation cephalosporins.
Listeria monocytogenes was not isolated from eggs either in the University poultry farm
or from retail market
` Chitosan maintained internal physical quality for longer duration than control at
280C and 40C. Coated eggs maintained higher weight and pH in storage. Nominal effect
on yolk colour was noticed upon coating. A three log reduction was seen in APC on
shell immediately after chitosan painting at both temperatures. Chitosan coating could
effectively preserve quality of duck eggs for a period of 28 days at 280C and four
months at 40C. There was no difference in visual perception upon coating. Chitosan 0.5
percent could be used in par with other disinfectants.
Thus, the points of lay and sales counter were found to be the major
contamination points as egg passed through the production chain. Litter disinfection and
personnel hygiene of handlers were recommended. Chitosan could be used as
disinfectant or as paint to bring down the microbial load and improve quality of duck
eggs during storage.
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