Rancidity in fats and fat-bearing materials, the development of which is known to be associated with certain oxidative changes in the fat, with the characteristic odors and flavours due to formation of various aldehydes, ketones and acids, raises a problem particularly in the fishery industry, because fish oils are highly unsaturated and therefore extremely susceptible to the oxidative deterioration. Though many antioxidant substances have been reported by various authors, the action of smoking or of wood-tar to reduce the rancidity of fish oil, has not yet been noticed. Such property of the smoking process can, nevertheless, easily be supposed to exist, seeing from the fact that smoked fishery products do not develop. unplea-sant odor in preservation.
The present paper reports that smoking, adding of wood-tar (Pix Liquida), and that of creosote show indeed the specific power to retard oxidative changes in fish oils. To indicate the rancidity, the determination of peroxide,
KEIS
test after T
AFFEL method and determina-tion of iodine value by W
IJS method were carried out with the results as shown in Table 1 and Figs. 1 to 5.
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