Land Animal Fats

The depot fats and organ fats of domestic animals, such as cattle and hogs, and milk fat, which was covered in Chapter 10, are important animal raw materials for fat production. The role of sheep fat, however, is not significant. The major fatty acids of these three sources are oleic, stearic and palmitic (Table 14.3). 

It should be noted that the fatty acid composition of individual fat samples may vary greatly. The fat composition of land animals is affected by the kind and breed of animal and by the feed. The composition of plant fats depends on the culti-var and growth environment, i. e. climate and geographical location of the oilseed or fruit plant (cf. Fig. 3.3.1.5). Therefore only average values are given in the following tables dealing with fatty acid composition. 

In contrast to oil from plant tissue, the recovery of animal fat is not restricted by rigid cell walls or sclerenchyma supporting tissue. Only heating is needed to release fat from adipose tissue (dry or wet rendering with hot water or steam). The fat expands when heated, tearing the adipose tissue cell membrane and flowing freely. Further fat separation is simple and does not pose a technical problem (Fig. 14.1). 

Continent Linseed Safflower seed Cottonseed Copra 

Continent Palm kernel Palm oil Olives Olive oil 

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Naturally occurring oils and fats constitute another important source of renewable raw materials [198]. Whether they are referred to as fats or oils depends on whether they are solid or liquid at room temperature, respectively. They are composed primarily of triglycerides (triesters of glycerol) together with small amounts of free fatty acids, phospholipids, sterols, terpenes, waxes and vitamins. Oils and fats are either of vegetable or animal origin and are produced in the approximate proportions 55% vegetable oils, 40% land-animal fats and 5% marine oils [199]. 

The milks of all mammals contain lipids but the concentration varies widely between species from c. 2% to greater than 50% (Table 3.1). The principal function of dietary lipids is to serve as a source of energy for the neonate and the fat content in milk largely reflects the energy requirements of the species, e.g. land animals indigenous to cold environments and marine mammals secrete high levels of lipids in their milks. 

Depot fats of higher land animals consist mainly of palmitic, oleic, and stearic acid and are high in saturated fatty acids. 

The depot fats of higher land animals, especially mammals, have relatively simple fatty acid composition. The fats of birds are somewhat more complex. The fatty acid compositions of the major food fats of this... 

This chapter will consider contemporary aspects of the classihcation, composition, properties, production, processing, and consumption of the depot lipids of land animals. For a more detailed discussion, the reader is referred to the recent comprehensive animal fats text (1). Additional discussions of the material covered here, and related topics, are found in excellent contemporary texts (2-4). Some consideration of greases will also be included here, because these are largely handled by and traded within the animal fats sector of the lipid industry. Discussions of mUk-fats and hsh oils can be found elsewhere in this series. 

Product obtained by heating, drying and grinding whole or parts of warm-blooded land animals from which the fat has been partially removed. This product contains less than 7.5% fat (as fed) (n = 114). At the time of writing, the sale and use of this product are prohibited in the European Union and in other countries. 

Palmitic acid is the most widely occurring saturated acid, being present in practically every fat examined. It is present in fish oils (10-30%), in the milk and depot fats of land animals (up to 30%), and in vegetable fats. Useful sources of this acid include cottonseed oil (17-31%, Section 3.3.10), palm oil (32-59%, Section 3.3.24), Chinese vegetable tallow (60-70%, Section 3.3.6), and animal fats from pig, sheep and cattle (25-37%, Section 3.4.2). 

The positional distributions of fatty acids in the triglycerides of the depot fats of some land animals are given in Table 3.175. The positional distributions of fatty acids in bird and reptile fats are given in Table 3.176. 

The fish are landed daily from inshore fishing boats or stored in ice in the case of deep-sea boats. The fish oil/meal plants are either in mother ships or, more usually, located in the fishing ports. The same conditions of storage, hygiene and daily use apply as in the treatment of animal fats. 

Within individual animals, subcutaneous fats contain a higher proportion of unsaturated acids and are thus softer than deep-body fat. The physical nature of fat varies between animals, marine mammals having softer body fat than land mammals. The reason in both cases is that animal fat has to maintain a degree of malleability at the temperature of the tissue, which is influenced by ambient temperatures. Thus, the fats... 

N.B. (i) Fats of land animals are solid or semi-solid and are composed almost entirely of Ci6 and C,s acids. Fats of ruminants contain nearly 60% of saturated acids... 

Product obtained hy heating, drying, and grinding whole or parts of warm-hlooded land animals from which the fat may have been partially extracted or physically removed. The product must be substantially free of hooves, horns, bristle, hair, and feathers, as well as digestive tract content. (Minimum crude protein content 500 g kg on a dry matter basis)... 

Product obtained by drying the blood of slaughtered warm-blooded animals. The product must be substantially free of foreign matter Product composed of fat from warm-blooded land animals... 

However, the Inuit peoples of Alaska have a diet with high levels of unsaturated fats as well as high levels of blood cholesterol, but they have a very low occurrence of heart disease. The fats in the Inuit diet are primarily unsaturated fats from fish rather than from land animals. 

Because unsaturated fats are now recognized as being more beneficial to health than saturated fats, American diets have changed to include more unsaturated fats and less saturated fatty acids. This change is a response to research that indicates that atherosclerosis and heart disease are associated with high levels of fats in the diet. However, the Inuit people of Alaska have a diet with high levels of unsaturated fats as well as high levels of blood cholesterol, but a very low occurrence of atherosclerosis and heart attacks. The fats in the Inuit diet are primarily unsaturated fats from fish, rather than from land animals. 

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