Effect of Different Sources of Heat on Nutritional Composition of Tilapia Fish (Oreochromis niloticus)

Abstract

A study was conducted to investigate the effect of traditional smoking methods on fresh tilapia fish (Oreochromis niloticus). For this purpose, proximate, mineral and amino acid compositions of tilapia fish smoked with sawdust, rice bran, melon husk and electric oven (control) heat treatments were determined using standard analytical technique. The results showed that crude protein content (%) ranged between 55.10 to 64.16% with the highest value recorded in sample smoked with rice bran heat treatment while crude fat had the highest value (18.10%) also in rice bran smoked sample. Sodium was found to be more abundant in all the samples (5.75 – 10.10 mg/100g) compared with magnesium (5.45 – 9.15 mg/100g), potassium (4.55 – 6.45 mg/100g) and phosphorus (4.70 – 6.00 mg/100g) while the least abundant mineral was chromium (0.05 – 0.15 mg/100g). The harmful metals such as cadmium and lead were not at detectable range of atomic absorption spectrophotometer (AAS). The amino acid profile revealed that only Oreochromis niloticus fish sample smoked with sawdust enhanced the contents of total amino acid (TAA), total essential amino acid (TEAA) and total sulphur amino acid (TSAA) by 3.77, 3.95 and 7.03%, respectively while melon husk and rice bran heat treatments reduced TAA, TEAA and TSAA. The limiting amino acid (LAA) for all the samples with different heat treatments was Ile except sample smoked with rice bran which has Val as LAA. Generally, all the smoked samples contained nutritionally useful quantities of total essential amino acids.

Keywords: Oreochromis niloticus, agricultural wastes, smoke, proximate, amino acids.