Fish products chemical components

The rendering process converts raw animal or fish tissue into various protein, fat, and mineral products, all of which are transformed into rich granular-type powders and fats with specific nutritional and chemical components. The animal byproduct raw material has approximately 60%-f of water and yields about 20% protein and 20% fat. These protein, fat, and mineral fractions are then available for a variety of uses. The annual volume in the United States approximates 4.2 million metric tons of animal protein and 4.2 million tons of rendered fat. 

As for meat and meat products, the most common reason for applying NIR spectroscopy on fish and fish products is to measure the fat, moisture, and protein contents. First, destructive NIR measurements on freeze-dried, cross-sectioned, and homogenized samples will be discussed. Second, nondestructive NIR measurements on fillets, and whole postmortem and live fish will be discussed. Finally, NIR prediction of minor chemical components will be briefly discussed. 

If that does occur, then the present system of classification of oils may be impossible to police, and a modified system may become necessary. Perhaps the sale and perceived value of oils will necessarily become dependent on the performance, not the source of the oil. With bulk oils such as palm, peanut, sunflower, safflower, sesame, soya, rapeseed, com, fish, and animal fats and oils, the fatty acid composition will obviously be important for health reasons. If the oil is to be used for frying then the frying properties will be important. In the case of palm products the physical properties and minor components such as carotenoids will be defined. Similarly animal fats will be judged mainly on physical behaviour and effect on the product in which they are used. In all cases the oxidative and stability of the oil will have to be defined. Sesame is a very stable oil, and thus its stability, together with its low level of linolenic acid, would be its major attribute, except for toasted sesame, which would probably be classed as a specialist oil. Already most baking fats sold to the public are blends developed to give the best performance, with no mention on the pack as to the source. If a bulk oil of this type had the desired chemical composition, stability and cooking behaviour, then perhaps the source would not be a matter of concern. 

Onchidal is a toxic component of a certain poisonous marine opisthobranch mollusc. Like other opisthobranchs, the Onchidiacea family of molluscs does not have the protection of a hard external shell as do most molluscs. They rely instead on the production of a defensive secretion. When the animal is disturbed it secretes a viscous fluid from specialized glands. In two species of Onchidella Onchidella Jhr-idanun and Onchidella borealis), this defensive secretion has been shown to act as a deterrent to potential predators, including fish and crabs. Chemically, it is a simple lipophilic acetate ester (see Figure 11.1). 

Finally, caprolactam could also be obtained by recycling polyamide-6 (PA-6) and polyamide-6,6 (PA-6,6) waste. Rhodia recycles about 30 000tons annually of PA-6 wastes in three different places in Europe. PA-6 production waste as well as used pure PA-6 wastes (fish nets and pure PA-6 fabrics) are used as starting products. PA-6,6 is also recycled. DSM and AlliedSignal opened a pilot plant in Richmond, Virginia, in 1997, where PA-6 carpets are depolymerized. The technology involves chemical processing of complete carpets without an expensive mechanical separation of fibers from the other carpet components. 

PCDDs are accidentally formed during the production of chlorinated phenols and related products (2-5). They may also be formed during the burning process in incinerators and through other forms of combustion, such as motor vehicles. The 2,3,7,8-TCDD is usually a minor component of these combustion products. They have been identified in urban dust, in gasoline motor oil, and in diesel motor oil (Ballschmiter, K. Buchert, H. Niemczy, K. R. Munder, A. Swerrev, M. Chemosphere in press 1986.) Thus, these chemicals are ubiquitous in our environment in very low concentrations and have been identified in fish, lake sediments, human adipose tissue, and milk (6-10). In addition, waste from the production of chlorinated phenols, if poorly controlled, may lead to heavier contamination in local areas (11). 

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