Effect Of Selected Washing Treatments And Drying Temperatures On Biochemical And Microbiological Quality Of Dagaa ( Rastrineobola Argentea )

Dagaa ( Rastrineobola Argentea ) is one of the most important fish foods for the low-income households in the Nyanza Province, Kenya. However, the off-flavour and off-odour that results from the traditional sun-drying process of sun-dried Dagaa is a major disincentive to the use of the fish for human consumption, hence leading to utilization in animal feed. Chemical analyses for pH, Thiobarbituric reactive substances (TBARS), Total volatile bases-nitrogen (TVBN) and aerobic bacterial counts were carried out on Dagaa sampled from various process steps within the open field sun-drying and market conditions. Dagaa was also oven-dried at 30oC, 40oC and 50oC after washing with selected solutions namely salted (3% sodium chloride), chlorinated solutions (100ppm) and potable tap water (control). Results indicated that TBARS values increased significantly (p<0.05) from 1.39 mgMA/kg in fresh fish to 10.55 mgMA/kg in the market samples. The TVBN values increased significantly (p<0.05) from 9.42 mgMA/kg in fresh fish to 29.51 mg/ 100g in the market samples.The pH values declined significantly (p<0.05) from pH 6.72 in the fresh fish to pH 5.88 in the market samples .Lipid oxidation (TBARS) was significantly (p<0.05) higher in Dagaa subjected to salted-wash treatments when compared to the chlorinated and control-wash treatments. The rate of lipid oxidation was significantly (p<0.05) higher at elevated temperatures of 50oC relative to 30oC and 40oC conditions. The TVBN levels observed in the salted and chlorinated-wash treatments showed significantly (p<0.05) lower TVBN values when compared with the control-wash treatments. However, the values of TVBN obtained at 30oC were significantly (p