Sensory and nutrient quality of wild captured Oreochromis shiranus (Boulenger, 1897) stored at ambient temperature

Abstract

Sensory and nutrient quality was determined for Oreochromis shiranus – a tilapia endemic to the Shire River, southern Malawi. Fish had highest sensory (when deep fried in edible vegetable cooking oil) and nutrient content (raw) up to 3 hours. Organoleptically, processed fish were still liked by consumers up to 12 hours of ambient storage. Deterioration in acceptability of the fish significantly increased between 6 and 9 hours by a difference of 2 while changes between 3 to 6 hours, then 9 to 12 hours had a difference of 1. A strong linear correlation between sensory scores and storage time at ambient temperature (R2 = 0.916) may suggest the importance of time in maintaining freshness quality of fish. Moisture fluctuated with storage time but without significant changes (P>0.05). Ash content increased with storage time while crude fat and crude protein decreased (P<0.05). Significant increase in ash and moisture content (P<0.05) were only reported at sensory rejection of the fish. There were no significant changes (P>0.05) in crude fat content between 3 and 6 hours while changes were observed at 0 (initial) and 12 hours (rejection time) of ambient storage (P<0.05). Crude protein content did not significantly change during the first 3 hours of ambient storage (P>0.05) but significant changes were recorded after 6 hours till sensory rejection of the fish (P<0.05). Nutrient levels remained high after 6 hours despite the drop in sensory quality after 3 hours suggesting that an organoleptically rejected product can still be nutritionally wholesome underscoring the need to validate sensory data with other tests.