Hydrogenated vegetable oil[edit source] In Pakistan, vanaspati is spelled "Banaspati". Vanaspati is also an Indian/South Asian slang for Vanaspati ghee, a fully or partially hydrogenated vegetable cooking oil, often used as a cheaper substitute for ghee. In India, vanaspati ghee is usually made from palm oil. Hydrogenation is performed using a catalyst known as "supported nickel catalyst", in reactors at low-medium pressure (3-10 bar). Vanaspati ghee is very high in trans fats, which may compose up to 50% of Vanaspati.[1] In the food industry[edit] The largest scale application of hydrogenation is for the processing of vegetable oils. Typical vegetable oils are derived from polyunsaturated fatty acids (containing more than one carbon-carbon double bonds). Their partial hydrogenation reduces most but not all, of these carbon-carbon double bonds. The degree of hydrogenation is controlled by restricting the amount of hydrogen, reaction temperature and time, and the catalyst.[18] Partial hydrogenation of a typical plant oil to a typical component of margarine. Most of the C=C double bonds are removed in this process, which elevates the melting point of the product. Hydrogenation converts liquid vegetable oils into solid or semi-solid fats, such as those present in margarine. Changing the degree of saturation of the fat changes some important physical properties such as the melting range, which is why liquid oils become semi-solid. Solid or semi-solid fats are preferred for baking because the way the fat mixes with flour produces a more desirable texture in the baked product. Because partially hydrogenated vegetable oils are cheaper than animal source fats, are available in a wide range of consistencies, and have other desirable characteristics (e.g., increased oxidative stability/longer shelf life), they are the predominant fats used as shortening in most commercial baked goods. Health implications[edit] A side effect of incomplete hydrogenation having implications for human health is the isomerization of some of the remaining unsaturated carbon bonds. The cis configuration of these double bonds predominates in the unprocessed fats in most edible fat sources, but incomplete hydrogenation partially converts these molecules to trans isomers, which have been implicated in circulatory diseases including heart disease. The conversion from cis to trans bonds is favored because the trans configuration has lower energy than the natural cis one. At equilibrium, the trans/cis isomer ratio is about 2:1. Food legislation in the US and codes of practice in EU have long required labels declaring the fat content of foods in retail trade and, more recently, have also required declaration of the trans fat content. The use of trans fats in human food products has been effectively banned in Denmark (since 2003) and Switzerland (2008). In the US, local legislation banned trans fats from restaurants and public kitchens in New York City (since 2005) and California. Other countries and regions have introduced mandatory labeling of trans fats on food products and appealed to the industry for voluntary reductions.[19][20]
Posted on: Thu, 03 Oct 2013 19:13:19 +0000
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