Plasticity and Solubility of Fats

The plasticity of fat is its ability to hold its shape but still be molded or shaped under light pressure. Plasticity determines a fat’s spreadability. It is an important characteristic to consider when choosing which fat to use in the preparation of confections, icings, pastries, and other baked products. Although most fats look solid at room temperature, they are actually composed of liquid oil with a network of solid fat crystals holding it in place. This combinations allows the fat to be molded into various shapes. Chilled butter has very little plasticity as compared to hydrogenated vegetable oil, or shortening. The more unsaturated a fat is, the more plastic it will be. Temperature also influences plasticity, hard fats such as butter becoming soft and more spreadable when warmed.

Solubility of Fats

The chemical structure of fats makes them generally insoluble in water. Acetic acid, found in vinegar, dissolves in water because it is so short (only two carbons long), making it one of the few water-soluble fats. Other fats are soluble in organic compounds such as benzene, chloroform, and ether.

Flavor and Satiety of Fats

Fats contribute their own flavor, while also absorbing fat-soluble flavor compounds from other foods. Sauteing garlic, onions, and herbs in oil releases their flavorful and aromatic compounds and also lends them a smooth, rich mouthfeel. One of the most obvious contributions to flavor foods from fat is found in fried foods such as breaded poultry or fish, french fries, potato chips, and doughnuts.

Fats also contribute texture. The higher the fat content in ice cream, the smoother and more creamy the mouthfeel. The tenderizing effect of fats on foods makes them easier to chew and causes them to feel more moist in the mouth. The lubricating action of fat acts to moisten certain foods such as crackers and chips in which saliva would not be enough. These dry foods are processed in the mouth much more easily if they are coated with an oil or served with a high-fat dip or spread.

In addition to contributing to flavor and texture, fats also induce a sense of fullness, or satiety, because they take longer to digest than carbohydrates and proteins. They delay the emptying of the stomach contents, which makes a person feel full longer and delays the onset of the hunger pangs that signal time for the next meal.