Understanding Food Chapter 10: Fats and Oils

Functions of Fats in Food Shortening: A fat that tenderizes, or shortens, the texture of baked products by impeding gluten development, making them softer and easier to chew. We talked about this function when we studied cakes and breads. Emulsion: A liquid dispersed in another liquid with which it is usually immiscible (incapable of being mixed).

Functions of Fats in Food Shortening: A fat that tenderizes, or shortens, the texture of baked products by impeding gluten development, making them softer and easier to chew. Emulsion: A liquid dispersed in another liquid with which it is usually immiscible (incapable of being mixed). Surfactant: Surface-active agent that reduces a liquid’s surface tension to increase its wetting and blending ability. The shortening power is greater in a fat that contains more highly saturated fats.

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 Starting with “Heat transfer”, here is an example of how fat will cook a food. Dependent on the surface of the food will influence the amount of fat absorbed. Very porous (fish) will increase caloric value from 25/oz to 100/oz Less porous (chicken) will increase caloric value from 50/oz to 100/oz. How porous is the batter on foods? What do you think is the impact?

Functions of Fats in Food There are two types of emulsions: 1. Oil-in-water, in which oil droplets are dispersed throughout the water. 2. Water-in-oil, in which water droplets are dispersed throughout the oil.

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.

Functions of Fats in Food

Functions of Fats in Food Creaming: In an emulsion, the collection and rising of the lighter phase, usually oil, to the top of the mixture. Creaming is a process that achieves temporary emulsion status. Stabilizers may be added to an emulsion to decrease the tendency of the emulsion to separate, which creates a viscosity similar to soft yogurt; this is referred to as a semi-permanent emulsion. Permanent emulsions are very viscous and stable, to the point that they do not separate.

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

Functions of Fats in Food

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. Plasticity determines a fat’s spreadability Fats not only contribute their own flavor to foods, but also absorb fat-soluble flavor compounds from other foods. The tenderizing effect of fats on foods makes them easier to chew and causes them to feel more moist in the mouth

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. Fat also coats food with a sheen of delicate oil that improves the appeal of many foods. (1) Fats take longer to digest than carbohydrates and proteins. (2) Fats delay the emptying of the stomach contents, which makes a person feel full longer.

Types of Fats The different types of fats: Butter Margarine Shortenings Oils Lard Cocoa butter Fat replacers The desirability of fat’s presence in foods and its multiple roles in food preparation have led to many different types of fats being obtained from both animal and plant sources through the years.

Types of Fats Butter is made from the cream of milk.

Types of Fats Butter can be purchased in a number of forms. Choices are influenced by: Taste Texture Other options may include: Compound or flavored butter Powdered butter Clarified butter Brown or black butter Clarified butter: Butter whose milk solids and water have been removed and thus will not burn. Smoke point: The temperature at which fat or oil begins to smoke.

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. Regular margarine contains as many calories (kcal) as butter. Margarine may be made from soybean, corn, safflower, canola, or other partially hydrogenated vegetable oils. In addition, margarines usually contain the following: Cultured skim milk Emulsifiers such as lecithin Vitamins A and D Flavorings, usually diacetyl Food colorings, usually annatto and/or carotene

Types of Fats Diacetyl is added to margarine for flavoring because it is largely responsible, in addition to short fatty acids, for butter’s characteristic flavor

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. 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. 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.

Types of Fats 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. 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.

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. Lard - Was the major shortening in use in the early 1900s. Is used primarily in pastry pie crusts , commercial frying, and regional cooking.

Types of Fats Interesterification: A commercial process that rearranges fatty acids on the glycerol molecule in order to produce fat with a smoother consistency.

Fat Replacers Substitutes physically resemble fats, are often lipid based, and usually replace the fat in foods on a one-to-one basis to duplicate the functional properties of fat. Fat mimetics are water-soluble, often protein or carbohydrate based, and imitate the mouthfeel of fat. Fat-soluble substitutes and extenders replace the weight added by fat .

Fat Replacers

Food Preparation with Fats Flash point: The temperature at which tiny wisps of fire streak to the surface of a heated substance (such as oil). Fire point: The temperature at which a heated substance (such as oil) bursts into flames and burns for at least 5 seconds. Polymerization: A process in which free fatty acids link together, especially when overheated, resulting in a gummy, dark residue and an oil that is more viscous and prone to foaming.

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. Reducing the consumption of dietary fat may be accomplished by following the dietary guidelines recommending:

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 Other ways to reduce the amount or modify the type of fat in the diet include: Fruit preserves and honey can replace butter on breads. Mustard, ketchup, or low-fat salad dressing or mayonnaise may substitute for regular mayonnaise. Purées of fruits such as plums, dates, apples, and figs may replace some of the fat in recipes for baked products. Crumb crusts can replace standard pie crusts. Double-crust pies can be converted to one-crust pies. Automatically cutting fat by close to 50%. A nonfat condiment such as salsa, relish, or chutney can replace some of the butter or sour cream toppings on baked potatoes.

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.

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

Storage of Fats Hydrolytic Rancidity: Fats become rancid when exposed to water, usually the water found frozen on food to be fried. Oxidative Rancidity: Fats can also become rancid when they are exposed to the oxygen in air.

Storage of Fats Flavor reversion: The breakdown (oxidation) of an essential fatty acid, linolenic acid, found in certain vegetable oils, leading to an undesirable flavor change prior to the start of actual rancidity. The two most commonly used oils: Cottonseed Corn …are very resistant to flavor reversion.

Storage of Fats Preventing Rancidity Rancid products have reduced shelf lives and must be discarded. In the past, cereal manufacturers incorporated predominantly saturated fatty acids into their products to reduce the risk of rancidity.

Storage of Fats Avoid Oxygen and Heat: Pack items which are high in unsaturated fatty acids in vacuum packs or nitrogen to prevent contact with oxygen. Antioxidants: Added to foods containing large amounts of unsaturated fats to prevent rancidity.