Fats and Oils

Function of fat in heat transfer

transfers heat to food without burning

Shortening power of fats

impedes gluten formation, adds flakiness; saturated fat tends to be more useful as shortening for baked goods

emulsion

liquid dispersed in another liquid, usually non-homogenous; ex: oil in water

3 parts of an emulsion

dispersed or discontinuous phase: usually oil

dispersion medium or continuous phase: usually water

emulsifier

emulsifier

acts as a surfactant; reduces a liquid’s surface tension to increase its wetting and blending ability

What determines the melting point of fats?

degree of saturation (less saturated= lower melting point)

length of chain (longer chain=higher melting point)

cis-trans configuration (cis bend= lower melting point)

crystalline structure

plasticity

ability of solid fat to hold its shape but still be molded or shaped under light pressure

How does fat affect the texture of a food?

the tenderizing effect of fat makes foods easier to chew and causes foods to feel more moist in the mouth

Effect of fat on flavor of foods

fats contribute their own flavor to foods and the flavor is difficult to duplicate

How does fat affect satiety?

fat takes longer to digest than CHO and PRO, causing a longer-lasting satiety, also delays stomach emptying

winterized oils

removes components that would make the oil cloudy

interesterification

rearranges fatty acids on the glycerol molecule within TAG so they are more heterogeneous, resulting in smaller fat crystals and producing a smoother consistency fat

fat extenders

optimize the functionality of fat so that less fat is required

fat analogs

have the characteristics of fat but with fewer cals because of their altered digestion

fat mimetics

“mimics”the effects of fat, replicates creaminess/smoothness of fat

fat substitutes

have physical and sensory properties identical to those of fats but without the calories; often lipid-based

fats sources highest in monounsaturated fat

olive, canola, and peanut oil

fat sources highest in polyunsaturated fats

safflower, sunflower, corn, soybean, and cottonseed oil

fat sources highest in saturated fat

coconut and palm oil, butter, and lard

Which oils are ideal for frying?

Ones with a smoke point above 420F (avocado, soybean, peanut, corn, and most vegetable oils)

What is the optimal frying temperature and why?

375F, if the frying temperature is too low, the food will absorb too much fat and become soggy

rancidity

chemical deterioration of fats causes off flavors and rancid odors in the oils

hydrolytic rancidity

water hydrolyzes the bonds of triglycerides, causing them to break down into smaller fatty acids which have un unpleasant aroma and taste

oxidative rancidity

the double bond of an unsaturated fatty acids reacts chemically with oxygen to result in two or more shorter molecules

flavor reversion

breakdown of alpha linolenic acid into volatile molecules, causing off odors

How to prevent rancidity?

avoid oxygen and heat, add antioxidants