Chapter II: Raw Materials Used in the Manufacture of Edible Fats and Oils

It is unnecessary to emphasise the absolute importance that all materials used for the preparation of edible fats and oils should be as fresh, odourless, and free from all impurities as possible. Albuminous matter, which facilitates the production of rancidity by enzymic action, must be carefully removed, and freedom from any appreciable quantity of free fatty acids is most essential. The absence of these latter should be sufficient to guarantee the absence of any rancidity, which though not due to, is generally accompanied by their production.

The methods of treatment by which freedom from odour and free fatty acids is secured, are fully described in the next chapter, and in the case of some of the materials, their actual preparation is dealt with in subsequent chapters. The following paragraphs give briefly the source, origin, and properties of the raw material employed in the industry.

=Tallow.=—Ordinary “dripping” is simply an impure form of tallow, but the name tallow is generally used to denote the adipose fat or “suet” from sheep and oxen, being distinguished in commerce as mutton or beef tallow. The latter is somewhat softer in consistency, and is therefore more usually employed in the manufacture of margarine, though mutton tallow is also occasionally used. “Premier jus” consists of the less firm constituents of tallow, separated from the harder stearin by partial melting and pressure, as described in Chapter VI. p. 69.

The chief sources of imported tallow are Australia, New Zealand, and North and South America. Some of the carefully picked tallow intended for margarine making is shipped to England “unrendered,” but in some cases the fat is not only rendered, but also converted into “premier jus” abroad before shipment. Large quantities of tallow are also produced in Great Britain, and much of the rough fat is carefully hand-picked, rendered separately, and the product sold for margarine making. The following figures have been obtained for some typical samples of tallow:—

+-----------------+----------------+-----------------+--------+
| | | Free Acidity | |
| Tallows. | Saponification | (as Oleic Acid) | Titre, |
| | Value. | per cent. | °C. |
+-----------------+----------------+-----------------+--------+
| _Mutton_:— | | | |
|Selected English | 197·6 | 1·45 | 47 |
|Australian | 197·4 | 0·48 | 48·3 |
|South American | 197·3 | 1·11 | 47 |
|North American | 197·5 | 1·32 | 44 |
| | | | |
| _Beef_:— | | | |
|Selected English | 197·5 | 2·40 | 44 |
|Australian | 197·5 | 1·68 | 43·9 |
|South American | 197·3 | 0·81 | 45 |
|North American | 197·4 | 1·97 | 41·5 |
+-----------------+----------------+-----------------+--------+

=Lard.=—This fat, obtained from the pig, is an important constituent of many butter substitutes, especially in the United States, whence most of that imported into this country is obtained. Its method of preparation and various qualities are fully described in Chapter V.

=Lard Oil=, obtained by subjecting the softer varieties of lard to hydraulic pressure at a moderate temperature, is also dealt with in