Margarine - Manufacture

Manufacture

The basic method of making margarine today consists, as it did in Mège-Mouriés day, of emulsifying a blend of hydrogenated vegetable oils with skimmed milk, chilling the mixture to solidify it and working it to improve the texture. Vegetable and animal fats are similar compounds with different melting points. Those fats that are liquid at room temperature are generally known as oils. The melting points are related to the presence of carbon-carbon double bonds in the fatty acids components. Higher number of double bonds give lower melting points.

Commonly, the natural oils are hydrogenated by passing hydrogen through the oil in the presence of a nickel catalyst, under controlled conditions. The addition of hydrogen to the unsaturated bonds (alkenic double C=C bonds) results in saturated C-C bonds, effectively increasing the melting point of the oil and thus "hardening" it. This is due to the increase in van der Waals' forces between the saturated molecules compared with the unsaturated molecules. However, as there are possible health benefits in limiting the amount of saturated fats in the human diet, the process is controlled so that only enough of the bonds are hydrogenated to give the required texture. Margarines manufactured in this way are said to contain hydrogenated fat. This method is used today for some margarines although the process has been developed and sometimes other metal catalysts are used such as palladium. If hydrogenation is incomplete (partial hardening), the relatively high temperatures used in the hydrogenation process tend to flip some of the carbon-carbon double bonds into the "trans" form. If these particular bonds aren't hydrogenated during the process, they will still be present in the final margarine in molecules of trans fats, the consumption of which has been shown to be a risk factor for cardiovascular disease. For this reason, partially hardened fats are used less and less in the margarine industry. Some tropical oils, such as palm oil and coconut oil, are naturally semi solid and do not require hydrogenation.

Modern margarines can be made from any of a wide variety of animal or vegetable fats, mixed with skim milk, salt, and emulsifiers. Margarines and vegetable fat spreads found in the market can range from 10 to 90% fat. Depending on its final fat content and its purpose (spreading, cooking or baking), the level of water and the vegetable oils used will slightly vary. The oil is pressed from seeds and refined. It is then blended with solid fat. If no solid fats are added to the vegetable oils, the latter undergo a full or partial hydrogenation process to solidify them. The resulting blend is mixed with water, citric acid, carotenoids, vitamins and milk powder. Emulsifiers such as lecithin help disperse the water phase evenly throughout the oil, and salt and preservatives are also commonly added. This oil and water emulsion is then heated, blended, and cooled. The softer tub margarines are made with less hydrogenated, more liquid, oils than block margarines.

Three types of margarine are common:

• Soft vegetable fat spreads, high in mono- or polyunsaturated fats, which are made from safflower, sunflower, soybean, cottonseed, rapeseed, or olive oil.
• Margarines in bottle to cook or top dishes
• Hard, generally uncolored margarine for cooking or baking. (Shortening)