Determination of fat, protein and dry matter content of fish by mid-infrared transmission spectroscopy

A simple, fast and accurate method for making multicomponent analyses of fish meat using mid-infrared (IR) absorption technique is presented. Basically, the method involves dissolving fish meat in an alkaline detergent with a blender, forming a suspension that can be analysed with commercial milk infrared analysers. Various types and concentrations of detergents and two blending times were evaluated. The relative repeatabilities, expressed as the residual standard deviation in relation to the corresponding means, of the method were less than 0-5%, and relative accuracies were less than 2% for fat and total solids and less than 1% for protein. Possible ways to improve the method further are discussed.