QUALITY CHANGES AND HEAVY METAL ANALYSIS OF MARINE WATER PRAWN AND FRESH WATER PRAWN STORED IN ICE - Penaeus notialis/Macrobrachium vollenhovenii

摘要

Sensory evaluation, microbiological examination and heavy metal analysis of marine water prawn (Penaeus notialis) and freshwater prawn (Macrobrachium vollenhovenii) during storage in ice were determined. Sensory evaluation of raw prawns based on colour, odour and texture showed deterioration after the 8th day in ice. The successions of bacterial genera during the storage in ice were Bacillus, Corynebacteria, Escherichia coli, Klebsiella sp., Salmonella and Shigella for both types of prawns. The meantotal bacterial counts were 1.17 x 10~7 Cfu/g and 1.23 x 10~7 Cfu/g for P. notialis and M vollenhovenii, respectively. There was no significant difference (p>0.05) in the total bacterial counts for both types of prawn. However, there was a correlation (r= 0.7) between storage days in ice and total bacterial counts for the two types of prawn. The levels of cadmium, lead, copper, zinc, chromium, iron, cobalt, nickel and manganese in the tissues of P. notialis and M. vollenhovenii were 0.28 mu g/g, 0.96 mu g/g, 6.15 mu g/g, 0.56 mu g/g, 15.0 mu g/g, 1.14 mu g/g, 5.52 mu g/g, 2.05 mu g/g, 1.82 mu g/g, and 0.33 mu g/g, 1.25 mu g/g, 5.40 mu g/g, 1.54 mu g/g, 2.61 mu g/g, 2.04 mu g/g, 5.69 mu g/g, 1.52 mu g/g, 0.45 mu g/g, respectively. These levels for bothtypes of prawn were lower than the maximum permissible international standards, implying that there is little or no possibility of heavy metal toxicity hazards associated with consumption of the prawns and suggesting that they were caught from waters relatively free from pollution by heavy metals.