Working Characteristics of Fats & Oils

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Shortening
Flour grains become coated in fat, which prevents the gluten from developing as contact with water is inhibited. The protein remains in short strands, producing a crumbly, buttery texture
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Aeration
In rich cakes fat can hold and trap air. This helps give the cake a good volume and texture eg. Victoria sandwich cake
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Emulsification
Used to ensure food products stay in good stable condition. Allows oils and water to be combined, as droplets of one in the other. Emulsifiers have a hydrophillic and hydrophobic end. Used in salad dressings and mayo.
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Lubrication
In shallow frying fat or oil prevents food sticking to the cooking surface eg. in baking fat is used to grease the tin
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Plasticity
It is the ability to be moulded or shaped under pressure, and determines fats spreadability. The more unsaturated the fat is, the more plastic it will be. Depends on the chemical structure due to the mixture of triglycerides. Think chocolate melting.
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Uses in Cakes
Aeration; flavour; texture; increasing shelf life; rich cake; colour
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Uses in Pastry
Shortening; flavour; colour; fat is used differently in different pastries eg. shortening in shortcrust, makes layers in flaky.
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Uses in Bread
Soft crumb; texture; flavour; in specific breads oil is added such as in foccacia , in Chelsea buns butter is added
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Sealing
Fat can be used as a moisture repelling seal eg. melted butter is used to cover pate
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Glazing
Shiny finish on foods, sources of glazing made with little or no fat tend to have a dull appearance
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Melting Points
Point at which a solid becomes a liquid, and this depends on the type of fat. Higher melting point is due to the fat being more saturated with hydrogen
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Hazing Points
Points at which a shimmer or faint blue haze appears over a fat (such as oil), it indicates the ideal heat for frying
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Hydrolytic Rancidity
Caused by exposure to water, occurs in all fats. The resulting reaction causes the fat molecule to split and produce free fatty acids, which are smelly and bitter. This reaction is aided by heat and enzymes (eg. lipases)
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Oxidative Rancidity
Occurs in unsaturated fats primarily, due to the reactivity of the double bonds. Oxygen molecules interact with the fats structure to alter odour and taste. Fatty acids react with O2 to produce free radicals
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Fatty Acids
Hydrocarbon chains with an acid group on the end (RCOOH). They may be either saturated or unsaturated, depending on how many double bonds they contain.
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Hydrogenation
Turns unsaturated fats into saturated fats, to give a spreadable consistency. Accomplished by bubbling hydrogen through the oil, the weak double bonds break and hydrogen joins on to them. Trans fatty acids may be formed due to geometric isomerism.
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Other cards in this set

Card 2

Front

In rich cakes fat can hold and trap air. This helps give the cake a good volume and texture eg. Victoria sandwich cake

Back

Aeration

Card 3

Front

Used to ensure food products stay in good stable condition. Allows oils and water to be combined, as droplets of one in the other. Emulsifiers have a hydrophillic and hydrophobic end. Used in salad dressings and mayo.

Back

Preview of the back of card 3

Card 4

Front

In shallow frying fat or oil prevents food sticking to the cooking surface eg. in baking fat is used to grease the tin

Back

Preview of the back of card 4

Card 5

Front

It is the ability to be moulded or shaped under pressure, and determines fats spreadability. The more unsaturated the fat is, the more plastic it will be. Depends on the chemical structure due to the mixture of triglycerides. Think chocolate melting.

Back

Preview of the back of card 5
View more cards

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