Microbial fats and oils and their fractions

15.16 Animal or vegetable fats and oils and their fractions, partly or wholly hydrogenated, inter-esterified, re-esterified or elaidinised, whether or not refined, but not further prepared. 1516.10 - Animal fats and oils and their fiactions 1516.20 - Vegetable fats and oils and their fractions This heading covers animal or vegetable fats and oils, which have undergone a specific chemical transformation of a kind mentioned below, but have not been further prepared. The heading also covers similarly treated fiactions of animal or vegetable fats and oils. (A) Hydrogenated fats and oils. a Hydrogenation, which is effected by bringing the products into contact with pure hydro en at a su~tabletern erature and pressure in the presence of a catalyst (usually finel divi ed nickel), raises &e melting points of fats and increases the consistency ofY oils by transforming unsaturated glycerides (e.g., of oleic, linoleic, etc., acids) into saturated lycerides of higher melting oints (e-g., of almitic, stearic, etc., acids). The degree of gYdrogenation and the fina? consistency o the products depend on the conditions employed in the process and the length of treatment. The headmg covers such products whether they have been : ! L (1) Pastly h drogenated even if these products tend to separate into pasty and liquid layers). his also has e effect of converting the cis-form of the unsaturated fatty acids into the trans-form in order to raise the melfmg point. ? (2) Wholly hydrogenated (e.g., oils converted into pasty or solid fats). The products most commonly h drogenated are oils of fish or marine mammals and certain vegetable oils (cotton-see oil, sesame oil, ground-nut oil, colza oil, soya-bean oil, maize (corn) oil, etc.). Wholly or part1 hydrogenated oils of this type are fkequently used as constituents in the preparation of e 'ble fats of heading 15.17, since the hydrogenation not on1 increases their consistency but also makes them less liable to deterioration by atmosp eric oxidation, and improves their taste and odour, and, by bleaching them, gives them a better appearance. d' i This part also covers hydrogenated castor oil, so called " opal wax ". (B) Inter-esterified, re-esterified or elaidinised fats and oils. (1) Inter-esterified (or trans-esterified) fats and oils. The consistency of an oil or fat can be increased by suitable rearrangement of the fatty acid radicals in the triglycerides contained in the product. The necessary interaction and rearrangements of the esters is stimulated by the use of catalysts. (2) Re-esterifred fats and oils (also called esterified fats and oils) are triglycerides obtained by direct synthesis fiom lycerol with mixtures of free fatty acids or acid oils horn refining. The man ement o the fatty acid radicals in the triglycerides is different fiom that normally foun in natural oils. f k Oils obtained fiom olives, containing re-esterified oils, fall in this heading. (3) Elaidinised fats and oils are fats and oils processed in such a way that the unsaturated fatty acid radicals are substantially converted fi-om the cis-form to the corresponding trans-form. The heading includes the roducts as described above, even if they have a waxy character and even if they have been suflsequently deodorised or subjected to similar refining processes, and whether or not they can be used & r e d as food. But it excludes hydrogenated, etc., fats and oils and their fractions which have un ergone such further pre aration for food purposes as texturation (modification of the texture or crystalline structure) heading 15.17). The heading further excludes hydrogenated, inter-esterified, re-esterified or e aidinised fats and oils or ther fractions, where modification involves more than one fat or oil (heading 15.17 or 15.18). i e -