Understanding Food

1. Understanding Food Chapter 10: Fats and Oils

2. Functions of Fats in Food

3. Functions of Fats in Food-Heat transfer How is food heated in deep-fat frying? • In deep-fat frying, food is quickly cooked in several stages involving: • Moisture transfer • Fat transfer • Crust formation • Interior cooking

4. Functions of Fats in Food-emulsions There are three parts to an emulsion: • The dispersed or discontinuous phase, usually oil. • The dispersion or continuous phase, most likely water-based. • An emulsifier, which is a stabilizing compound that helps keep one phase dispersed in the other.

5. Functions of Fats in Food • Fat’s melting point is determined by the following four characteristics of the fatty acid: • Degree of saturation • Length • Cis-trans configuration • Crystalline structure

6. Functions of Fats in Food Plasticity • The plasticity of fat is its ability to hold its shape but still be molded or shaped under light pressure. Flavor • The flavor developed in certain foods by fats is very difficult to duplicate. Texture • Fats also contribute texture.

7. Functions of Fats in Food Appearance • Foods are made more appealing by pigments located in a food’s natural fats. Satiety or Feeling Full • Fats induce a sense of fullness, or satiety.

8. Types of Fats • The different types of fats: • Butter • Margarine • Shortenings • Oils • Lard • Cocoa butter • Fat replacers

9. Types of Fats • Butter can be purchased in a number of forms. Choices are influenced by: • Taste • Texture • Standard stick margarine must contain at least 80% fat, about 16% water, and 4% milk solids.

10. Types of Fats • Shortenings are plant oils that have been hydrogenated to make them more solid and pliable. • Many different types of oils are available for food preparation purposes, and the type of oil used depends on the desired outcome.

11. Many refined oils are without any distinguishing characteristics. Unrefined, cold-pressed oils, such as peanut and olive oils, have the full flavor of the plants from which they were pressed. Winterizing:A commercial process that removes the fatty acids having a tendency to crystallize and make vegetable oils appear cloudy. Hydrogenation:A commercial process in which hydrogen atoms are added to the double bonds in monounsaturated or polyunsaturated fatty acids to make them more saturated. Types of Fats

12. Types of Fats • These animal sources of fat are primarily saturated fat: • Lard, which is the fat from swine. • Tallow is also an animal fat, but it is derived from beef cattle or sheep. • Suet is the solid fat found around the kidneys and loin of beef and sheep.

13. Food Preparation with Fats Lower-Fat Preparation Techniques • Meal patterns that are lower in fat. • Especially lower in saturated fat. • Rely on lower-fat or nonfat cooking methods. • Reduce the fat in recipes.

14. Food Preparation with Fats Other ways to reduce the amount or modify the type of fat in the diet include: • Fruit preserves and honey • Mustard, ketchup, or low-fat salad dressing or mayonnaise • Purées of fruits such as plums, dates, apples, and figs • Crumb crusts • Double-crust pies can be converted to one-crust pies. • A nonfat condiment such as salsa, relish, or chutney

16. Storage of Fats Storage of fat depends on its type. • Fats such as butter and margarine are best stored in the refrigerator. • Shortenings and most oils are usually stored at room temperature and should be kept tightly covered in a dark spot on the cupboard shelf. • They will keep longer if refrigerated. • Olive oil has a shorter shelf life than most vegetable oils and should be refrigerated fairly soon after opening.

17. Storage of Fats • Rancidity: the chemical deterioration of fats, which occurs when the triglyceride molecule and/or the fatty acids attached to the glycerol molecule are broken down into smaller units that yield off-flavors and odors. • There are two basic types of rancidity: • Hydrolytic rancidity • Oxidative rancidity