Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.

A sensitive accurate colorimetric method for trimethylamine determination is presented, based on the extraction with toluene of an alkaline sample containing 0.002 to 0.02 mg. trimethylamine nitrogen, and the formation of the yellow coloured picrate by mixing with a picric acid reagent. The application of the method in fishery products and effects of interfering substances have been investigated.

Relatively large amounts of nonvolatile higher amines are formed during proteolysis of fish muscle by bacteria. This follows closely the formation of trimethylamine. Fresh fish contain 0.2 mg. nitrogen per 100 g, muscle as trimethylamine and about 0.1 mg. nitrogen per 100 g. as dimethylamine. Trichloracetic acid and formaldehyde solutions completely extracted trimethylamine from fish and satisfactory recovery of added trimethylamine was obtained.

Methods for the extraction of protein from fish muscle have been studied. Using the Waring Blendor to obtain fine subdivision, up to 95 per cent of the fish muscle protein can be extracted with 5 per cent sodium chloride. Optimum pH for extraction was pH 7–9, and the optimum salt concentration 3 to 5 per cent. About 3 per cent stroma protein, collagen and elastin, was found in cod and haddock muscle. Myosin constituted about 75 to 80 per cent of the total protein. Globulin X, myogen, and myoalbumin made up about 20 per cent of the protein.

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