Original Research Article
Mortality and microbial diversity of raw, processed and storage of mangrove oysters (Crassostrea gasar)
Author’s E-mail: lawrenceamadi(at)ymail.com
Tel: +2348150610727
Lawrence O. Amadi |
Article Number: irjpeh.16.002 | Pages: 7-14 | Vol.3 (1), January 2016 | DOI: http://dx.doi.org/10.15739/irjpeh.16.002
Received: December 19, 2015 Accepted: January 22, 2016 Published: January 28, 2016
Abstract
Mortality and microbial diversity of raw, processed and storage of mangrove oysters at ambient temperature were investigated. The mortality rates of raw (shell-stock) oysters were determined during depuration in tap water (TW) and brackish water (BW) microcosms for 14days. Mortalities were observed on the 5th and 11th days and afterwards in TW and BW microcosms respectively. Thus, indicating the beneficial effects of depuration of mangrove oysters in BW than in TW microcosms. The microbial counts of raw, processed and storage of oyster meat samples were determined using standard microbiological methods. Aerobic plate counts (APCs) were 1.36×105 and 3.00×103 CFU/g for raw and processed oyster meats on day 0 (d0) respectively but increased markedly to 1.55×106 CFU/g in the processed meat sample during storage for 24h. Fungi counts were 3.6×102 and zero/no growth detected (NGD) CFU/g for raw and process oyster meats on d0 respectively but increased from 0- 0.8×102 CFU/g in the processed meat samples at storage. Bacteria were more predominant in numbers and diversity than fungi. The most frequently isolated microflora from raw and processed and during the storage of oyster meat samples consists of Bacillus, Pseudomonas, Vibrio, Proteus, Staphylococcus others are Aspergillus, Penicillium and Fusarium. The most dominant genera during storage were Bacillus (20.8%) and Pseudomonas (16.7%); Aspergillus (52.3%) and Penicillium (45.4%). However, nondetectability of E. coli and Acinetobacter species following processing and storage underscores the criticality and importance of adequate processing prior to consumption of mangrove oysters as some of these organisms are not only potentially pathogenic but of public health significance. From this study, it is also advisable that oyster farmers should market their raw produce on/before 5days for the depurated, and 24h for the processed meat samples to avoid serious postharvest economic loses.
Keywords: Mangrove oyster, microcosms, microflora, mortality, processing, storage
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