Carcass fatty acid composition and sensory properties of Nile tilapia (Oreochromis niloticus) fed on oilseed meals with crude papain enzyme

Abstract

In this study, proximate body composition, fillets fatty acid and sensory properties of Nile tilapia fed on oilseed meals with crude papain enzyme were determined. A control diet (D1) of 300g/kg crude protein (CP) and (2900Kcal/kg) was formulated using fishmeal (Rastrionaebola argentea) (FM) and test diets by replacing 10% CP of FM by soybean meal (SBM) (D2), canola meal (CM) (D3) and sunflower meal (SFM) (D4). One hundred and one days feeding trial was conducted in a 4x2 factorial design on 4 diets (D1, D2, D3 and D4) with (0.06%) and (0%) enzyme using 720 Nile tilapia fingerlings (7±3g). Fish were fed twice daily at 5% of their biomass at 10am and 4pm in two equal meals. At the end of feeding trial, fish were starved for 24 hrs and weighed. A sample of ten fish representing the average weight of each replicated group was used. The fillets fatty acid profiles were determined by MPA FT-NIR spectrometer. Organoleptic tests of both fresh and steamed fish were carried out by eight semi trained panellists using 5-point hedonic scale. There was increase (p<0.05) in carcass proximate composition in all the treatments. Fillets fatty acid levels were influenced by the crude papain enzyme (p<0.05). Palmitic acid (C16:0), linoleic acid (C18:2n-6) and oleic acid (C18:1n-9) were the most abundant fatty acids in the fillets. Fish fed on fishmeal based diet recorded higher percentage (22.56) of polyunsaturated fatty acids (PUFA). There was significant difference among the treatments (p<0.05) for general appearance. Fish fed on crude papain enzyme treated diets were less preferred. It is recommended that more research be done on the effect of papain enzyme on the carcass fatty acid and sensory properties of farmed fish.