Oils and fats are important ingredients for:
- Foods (e.g. (low fat) margarine, frying fat, baking and roasting products, mayonnaise, sauces, ice cream, sweets, etc.)
- Washing and cleaning products (e.g. (textile) detergents, cleaning agents)
- Personal care products (e.g. hair care, skin and facial care, toilet soap, toothpaste, deodorant)
- Specialty chemicals (e.g. oleochemical products such as: fatty acids and glycerin, stearin, olein, amides, polymerised fatty acids)
- Special oils and fats (e.g. animal feed industry, chocolate and confectionery industry, technical industry).
The functional properties of a triglyceride are determined by the chemical properties (such as chain length, number of double bonds and the location of the double bond on the carbohydrate chain) and physical properties (such as melting point) of the fatty acids.
The fatty acids most present in the fat or oil determine the chemical and physical properties of the final fat or oil. If a fat mainly contains saturated fatty acids it will be solid at room temperature. Fats with a high content of unsaturated fatty acids have a low melting point, making them liquid at room temperature.
Specific food products require a certain hardness (e.g. biscuits) or, conversely, a certain softness (mayonnaise) of the fat. We can influence the melting behavior of a fat or oil by changing its fatty acid composition by oil modification and/or blending different fats and oils, as explained in the previous page.
In this module we highlight three important aspects of oils and fats in food preparation:
Deep frying provides the best heat transfer and the lowest risk of burning compared to other cooking methods. It is a very fast way to prepare food, resulting in a cooked inside and a crispy outside of the food. Deep-frying causes the product to brown and flavor to develop.
Not all oils and fats are suitable for deep frying. Oils with a high stability and a high smoke point are most suitable. Deep-frying fat must be heated to a maximum of 175°C and replaced after 5 to 7 deep-frying times. It's time to change when the frying fat:
- has a strong odor or taste
- changes to dark brown or black
- will smoke
- continues to foam after adding snacks
Crystallised fat provides structure and cool melting to margarine, pastry, Danish & cakes, chocolates & fillings, whipped/clottes creams & crèmes, ice cream and biscuits & cookies. The crystalline form depends on the cooling procedure. Consequently, the melting profile is different. How to get the right crystalline form is shown in this video about chocolate tempering.
Emulsifiers are needed in mixtures of oil and water in margarine, ice cream, and salad dressing. Emulsifiers form and stabilise oil-in-water emulsions (e.g. mayonnaise), uniformly disperse oil-soluble flavour compounds throughout a product, prevent large ice-crystal formation in frozen products (e.g., ice cream), and improve the volume, uniformity, and structure of baked products. Solid fat can act as an emulsifier when small fat crystals (<0.1 μ) keep water droplets separated. Margarine is considered a water-in-oil (w/o) emulsion; which means that the water (i.e. the dispersed phase) is distributed as droplets within the oil (i.e. the continuous phase). Seen under the microscope, margarine is a kind of sponge of oil in which water droplets are held by fat crystals that surround the droplets.