Hydrogenation of margarine

The invention of margarine making by Mege Mouries one hundred years ago was stimulated by the shortage of butter in Western Europe with its fast growing population. Margarine is a fatty food closely resembling butter.

However, the application of this new invention very soon led to a new shortage situation, namely with respect to the raw materials for margarine making. It was under this stimulus that Normann, near the turn of century, invented the catalytic hydrogenation of fatty acids. The aim of hydrogenation is to covert a liquid vegetable or fish oil to a fat with butter like consistency, by reducing the degree of unsaturation in its component fatty acids.

In order to convert the liquid linoleic oil (and its triglyceride) into soft solid margarine, hydrogen is bubbled through the oil in the presence of a nickel catalyst under fairly mild conditions (175-190°C, 20-40 p.s.i.). The amount of catalysts used in hydrogenation is usually about 10% of nickel on the weight of the oil for a fresh catalyst but rising to 1-2% for a poisoned or spent catalyst.

Hydrogenation in this way does a number of things. Firstly, hydrogen attaches to some of the double-bonded carbons, increasing the saturation level. In doing so, the molecules lose some of the rigidity associated with double bonds and so are able to flex.

By elimination of double bonds and by cis-trans isomerisation, hydrogenation of fats raises the melting point, and turning the oil into a solid fat.

The removal of some of the reactive double bonds in this way also reduces the chances of attack by oxygen, so that the fat becomes rancid much less readily, increasing its shelf-life. Superheated steam is then passed through the molten fat to remove any impurities (especially bad-smelling acids and aldehydes).

Margarine must also be a plastic as possible at lower temperatures, it must have sufficient solid glycerides at 21-27°C, that it may be formed and packed in the customary prints it should be able to hold its shape and not separate oil for a reasonable period of time at 27-32 °F and must melt completely at the temperature of the human body, on order not to be gummy in the mouth.

Hydrogenation also removes the coloration from the fat, artificial colouring agents made from carotenes of various kinds are added to make it appear yellow and buttery. Other additives include butanedione (to make it smell like butter), vitamins A and D, emulsifiers (to sharpen the flavour) and binding agents (lecithins) to hold the whole thing together.
Hydrogenation of margarine

Nutritional Processes: Gastrointestinal Tract

Nutritional Processes: Gastrointestinal Tract
The gastrointestinal tract (GI) is bordered by a layer of epithelial cells (with glands) sitting on a lamina propria (or basement membrane), comprising the mucosa and adjacent to the submucosa, which is penetrated by blood capillaries, lymphatics and nerves. Beneath the mucosa and submucosa are two layers of smooth muscle, lying in longitudinal and transverse directions, to allow contractions and peristalsis, Within the stomach , but particularly in the small intestine, the surface area of the mucosa is greatly increased. The mucosal and submucosal layer is folded into microscopic villi on the surface of larger folds or ridges. At the bases of the villi are the “crypts” where new epithelial cells are formed that migrate upward to the villi. These cells are sloughed off at a fairly rapid rate; the lifespan of villus cells in the small intestine is as little as 2 - 3 days (in man), that of colonic cells 3 – 8 days). Cells in the crypts include those with glandular and mucous-secreting functions, where as those in the villi are largely absorptive. Glandular cells are important in signaling the initiation and coordination of digestive processes, involving a large number of hormones neurotransmitters and paracrine factors. Mucous provided by “goblet” cells promotes lubrication within the lumen of the GI tract. In the small intestine, crypt cells are also the source of some digestive juices.

The epithelia cells of the mucosa have an apical (lumen –oriented) surface that is often additionally invaginated to form microvilli (or a brush border). In the small intestine the brush border contains transporter and some digestive enzymes. It is also more rigid than other parts of the cells membrane, a fact now attributed to high concentrations of sphingolipid in the outer half of the lipid bilayer. Surface cells are held together by tight junctions near the apical (top) parts of the cells. At the opposites (serosal) end, the cells membrane has a different (less rigid) structure (high in phosphatidyl-choline) and also serves different functions. Nutrients entering the blood or lymph for distribution to body tissues must first cross the brush border and ultimately the serosal surface of these cells to enter the intestinal fluid. Transport across either or both of these surfaces may be independently and/or differentially controlled, depending upon the nutrient. For there, capillaries and lymphatics take nutrients to the rest of the body. Nutrients not making it across the serosal membranes will remain with the mucosal cells until they are sloughed off, from whence they may be released by digestion and resorbed or lost with cell debris and bacteria in feces.
Nutritional Processes: Gastrointestinal Tract