Cooking fats

A good compilation of the functions of fats in various food products is available (26). Some functions are quite subtle, eg, fats lend sheen, color, color development, and crystallinity. One of the principal roles is that of texture modification which includes viscosity, tenderness (shortening), control of ice crystals, elasticity, and flakiness, as in puff pastry. Fats also contribute to moisture retention, flavor in cultured dairy products, and heat transfer in deep fried foods. For the new technology of microwave cooking, fats assist in the distribution of the heating patterns of microwave cooking. 

Filters in air-conditioning systems do not remove all the dirt from the air, and this will settle on duct walls. There is an increasing awareness that ducting systems can harhour a great deal of dirt, and that this dirt will hold bacteria, condensed oils such as cooking fats and nicotine, fungi and other contaminants. 

One possible use for the cooking fat left over after making french fries is to burn it as fuel. Write a balanced equation, and use the following data to calculate the amount of energy released (in kilojoules per milliliter) from the combustion of cooking fat ... 

This addition of hydrogen to an alkene, often called hydrogenation, is used commercially to convert unsaturated vegetable oils to the saturated fats used in margarine and cooking fats. 

Animal fats are subjected to deodorization when a very bland or essentially flavorless fat is desired, such as in margarines or cooking fats. The fats are heated at 200°C to 260°C in the absence of air (to prevent oxidation) and treated with dry steam under a vacuum of 5-10 milliatmospheres. Off-flavor compounds are volatile under these conditions and are captured and removed in the steam stream. In addition to flavor components, free fatty acids, which can also contribute undesirable flavors, and other minor constituents such as peroxides, sterols, sterol esters, toco-pherols, and other natural antioxidants are partially or completely removed from the fat by this treatment. 

Lard Lard is a traditional edible fat for Chinese people. Lard is generally prepared either by dry-rendering or by wet-rendering. The dry-rendered lard with pork back fat as the raw material usually has better flavor than the wet-rendered lard and is used as cooking fat or shortening. The wet-rendered lard with pork belly fat as the raw material usually has an undesirable flavor and must be refined before further use. 

Some unsaturated hydrocarbons are converted to saturated hydrocarbons in the manufacture of high-octane gasoline and aviation fuels. Unsaturated vegetable oils can also be converted to solid cooking fats (shortening) by hydrogenation of most of the carbon-carbon double bonds present (Figure 27-21). Most of the double bonds that remain are the trans- isomer. 

Recycling a number of examples are given where recycling is used. One interesting article is on the treatment of cooking fats to provide an alternative to diesel fuel. 

Lard refers to pig fat in both its rendered and unrendered forms. Lard was commonly used as a cooking fat or shortening, or as a spread similar to butter. Its use in contemporary cuisine has diminished because of health concerns posed by its saturated fat content and its often negative image. The culinary qualities of lard vary somewhat depending on the part of the pig from which the fat is taken and how the lard is processed. ... 

Sutherland, W.J., Walker, R.J., de Jong, S.A., van Rij, A.M., Phillips, V., and Walker, H.L. (1999) Reduced Post-Prandial Serum Paraoxonase Activity After a Meal Rich in Used Cooking Fat, Arterioscler. Thromb. Vase. Biol. 19,1340-1347. 

However, temperature and pressure often have a decisive influence on the chemical potential and therefore on the course of chemical processes. Water freezes in the cold and evaporates in the heat. Cooking fat melts in a frying pan and pudding gels while cooling, ice melts under the blades of ice skates, and butane gas becomes liquid when compressed. The chemical potential fi is not a material constant, but depends upon temperature, pressure, and a number of other parameters. 

Hydrogen can be added catalytically to the double bonds of an oil to convert it into a semisolid fat. For example, liquid soybean and other vegetable oils are hydrogenated to produce cooking fats and margarine. 

The apparent use of tablespreads, cooking fats, and salad oils in Canada over the years has been similar in total quantity to that reported for the United States (Rizek et ai, 1974 U.S. Department of Agriculture, 1977). However, a comparison of the data on Individual product categories shows... 

Men between 20 and 39 years showed the highest intake of fats in the Nutrition Canada Survey (Table 11). Vaisey et a/. (1973) carried out a controlled metabolic study In which young adults consumed a "typical" Canadian diet except that all tablespread, cooking fat, and salad oil were entirely rapeseed oil. The young males (19-28 years) in this study consumed an... 

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