Effect of local processing methods (boiling, frying and roasting) on the amino acid composition of four marine fishes commonly consumed in Nigeria

The effects of different processing methods on the amino acid contents of four marine fishes commonly consumed in Nigeria: Clupea harengus, Scomber scombrus, Trachurus trachurus and Urophycis tenuis were investigated. The samples were boiled, roasted over hot charcoal, or fried in any of four different oil types (palm oil, soybean oil, vegetable oil and groundnut oil). The total amino acids for all the fish samples ranged from 76.72 to 98.01 g/100 g protein and the total essential amino acids from 28.95 to 44.73 g/100 g protein. Frying reduced the total amino acid contents, with the lowest values obtained in samples fried in palm oil. Boiling and roasting increased the total amino acid contents, with the values higher in roasted than boiled samples. The percentage of essential amino acids reduced with processing in almost all samples, but the reduction was more pronounced in the fried samples. The raw, boiled and roasted samples had amino acid scores greater than 100%, while for the fried samples, the limiting amino acids were either leucine or threonine. The results showed that roasting and boiling had more desirable effects on the amino acid content of the fish samples. (C) 2010 Elsevier Ltd. All rights reserved.