ABSTRACT

This studv was carried out to evaluate the effects of depuration on nutrient composition and total heterotrophic bacteria in periwinkles (Tympanotonus fuscatus) harvested from Elechi creek (a polluted creek) in Rivers state. The depuration was carried out using flow-through method under running tap water in a segregated sterile plastic tank and the periwinkles were taken out before depuration and at intervals of 24, 48, 72 and 96 h ofdepuration for analysis on the microbial load (Total Heterotrophic Bacteria (THB) and Fecal Coliform Bacteria (FCB)), heavy metal (Chromium (Cr), Cadmium (Cd) and lead (Pb)) concentrations and the proximate composition. Physico-chemical analysis was carried on the tap water samples prior to and after depuration. One-way ANOVA was used to test the levels of significance (P < 0.05). There was progressive increase in the depurated water samples (96h) in salinity (5.72 mg/1), pH (7.77) and Dissolved Oxygen (DO) (5.89 mg/1) as well as slight decrease in temperature (27.8°C) and the turbidity values remained undetected throughout the process in comparison to the undepurated water sample which had salinity (4.28 mg/1), pH (6.80), DO (4.83 mg/1), temperature (28°C) and turbidity (0 NTU). The concentration of Cd and Pb in the samples (0 and 96 h) were not delected. Cr in the 0 and 96 h samples were 0.97 mg/kg and O.llmg/kg respectively. The proximate analysis revealed that the protein (14.42 to 14.72%), ash (1.05 to 1.13%) and moisture contents (81.41 to 82.28%) increased as fat and carbohydrate decreased during the process while the crude fiber was not detected in all the samples. The microbial results showed that the samples had unacceptable levels of THB with 7.11*105cfu/g (highest count) and 5.70xl05cfu/g (least count) while FCB was not detected in any of the samples. This study showed that the physicochemical parameters had no adverse effect on the samples thus aided in the purging out of contaminants (heavy metals and bacteria) from their guts which they imbibed from Elechi creek while enhancing their protein and ash content, thus demonstrating the benefits of depuration on the potential health risk and safety of Tympanotonusfuscatus prior to consumption.