Delaware Inland Bays and Market Oyster (Crassostrea virginica) Quality for Consumption

Abstract

Consumption of raw oysters is known to cause serious health conditions due to bioaccumulation of contaminants. As filter feeders, oysters ingest bacteria along with phytoplankton from their surrounding habitats. Ensuring seafood safety for human consumption is always a concern. Since oysters are consumed raw, disease causing organisms, environmental contaminants, toxins, chemicals, and even physical hazards such as soils and metals retained in the oysters can enter through feeding. The objective of this study was to determine the quality of oysters collected from Delaware Inland Bays (DIB) and compare them with market oysters. Environmental parameters were monitored from local waters of DIB classified as closed versus open for shellfish harvesting. Total aerobic bacteria and vibrio were higher in market oysters during the warmer months, with open water having the least microbial loads. There were no significant differences in total vibrio counts between the study sites (p=0.396), but significant differences were recorded over time (p=0.004). Water temperature and turbidity were directly proportional to total vibrio in oysters, and salinity was inversely related. Research findings in this study may help bring awareness of changes in bacterial loads due to seasonal changes and additional handling and storage.

Assessment of Vibrio parahaemolyticus levels in oysters (Crassostrea virginica) and seawater in Delaware Bay in relation to environmental conditions and the prevalence of molecular markers to identify pathogenic Vibrio parahaemolyticus strains

“…Spearman’s rank correlation analysis showed that water temperature is positively and significantly ( P < 0.05) correlated to the total V . parahaemolyticus (log 10 CFU/g or mL) levels in oyster and seawater samples ( Table 4 ), which is in agreement with previous studies [ 58 , 61 – 63 ]. Salinity had no significant correlation with total V .…”

“…time, study site, and water parameters (temperature and salinity) for oyster and seawater samples, respectively. Spearman's rank correlation analysis showed that water temperature is positively and significantly (P < 0.05) correlated to the total V. parahaemolyticus (log 10 CFU/g or mL) levels in oyster and seawater samples (Table 4), which is in agreement with previous studies [58,[61][62][63]. Salinity had no significant correlation with total V. parahaemolyticus (log 10 CFU/g or mL) levels in oyster and seawater samples (Table 4).…”

“…parahaemolyticus (CFU) levels, agree well with the strong correlations between water temperature and V . parahaemolyticus densities that are reported in the literature [ 58 , 61 – 63 ], indicating that V . parahaemolyticus levels increases with the rise of temperature and vice versa ( Table 3 ).…”

“…literature [58,[61][62][63], indicating that V. parahaemolyticus levels increases with the rise of temperature and vice versa ( Table 3). V. parahaemolyticus concentrations from seawater samples were notably lower than oyster samples ( Table 3), demonstrating that oysters can concentrate the Vibrio species higher than 10-fold compared to the surrounding water [8,9].…”

Supplementation of tuna hydrolysate and insect larvae improves fishmeal replacement efficacy of poultry by-product in Lates calcarifer (Bloch, 1790) juveniles

“…Texture profile in terms of hardness, cohesiveness, adhesiveness, springiness, gumminess, chewiness of fish fillet (three fish/treatment) were analysed by texture analyser TVT 6700 (PerkinElmer, Inc., Waltham, Middx, USA) and TexCal texture analyser software (version 5.0) 62 . Each sample was run in triplicate and expressed as force per g. Fillet colour coordinates (L*, a*, b*) were determined by calibrated BYK spectro-guide sphere gloss (BYK-Gardener USA, Columbia, MD, USA) 63 . 4 g of fillet were homogenized with 40 mL of distilled water and pH was determined in triplicate by Aqua-pH meter (TPS Pty Ltd, Brendale, QLD, AU) after calibrating at three-scale pH (pH 4, 7, 10) 64 .…”