Fats

-Fat-

Functions

· Convenient, concentrated source of energy

· Surrounds/protects certain vital organs (kidneys etc)

· Forms insulating layer beneath skin (preserve body heat)

· Forms part of structure of cell membranes

· Provides source of vitamins A, D, E and K

· Provides texture/flavour

· Feeling of fullness

Chemistry

Fats – solid at R.T

Oils – Liquid at R.T

Fats referred to both fats and oils – Carbon, Oxygen, Hydrogen

Fat molecules – 1 unit of glycerol + 3 fatty acids (triglycerol)

Saturated fatty acids

All carbon atoms saturated with hydrogen atoms

· Butyric acid (milk, butter)

· Palmitic acid (animal fats)

· Lauric acid (dairy foods, coconut oil)

· Stearic acid (beef fat)

Fats solid at R.T are mostly made up of saturated fatty acids

Unsaturated fatty acids

Some carbon atoms joined by double bond.

Monounsaturated – one double bond in molecule (oleic acid – animal/plant fats and oils)

Polyunsaturated – more than one double bond (linoleic acid, linolenic acid – vegetable oils)

Unsaturated fatty acids can be cis or trans, depending on how the atoms are arranged at double bonds. Cis is better than trans.

Sources

Most fats contain mixture of saturated/unsaturated. Affects hardness of fat.

Obtained from plants/animals

Visible fat (easy to detect)

· Fat on meat

· Butter, margarine, lard

· Cooking fats and oils

Invisible fat (constituent part of food)

· Lean meat (fat within muscle)

· Egg yolk

· Flesh of oily fish

· Nuts, seeds, fruits

· Prepared foods/fried foods

Animal Sources – meat, dairy produce, fish

Plant Sources – seeds, nuts and pulses, kernels, fruits (avocado)

Requirements

Essential fatty acids (EFAs)

Linoleic acid and linolenic acid – plant oils (brain development for babies)

Omega 3 and 6 - Oily fish (e.g. herrings, sardines)

Effect of heat

· Solid fats melt to become liquid oils when heated.

· Oil becomes thinner and begins to bubble (heating continues)

· Very high temp – fat molecules decompose

· Blue haze, smoke, ignites and burns rapidly

How does fat tenderize baked products?

· Fat acts as a ‘shortener’

· Gluten (tough, stretchy substance) produced when flour and water mixed.

· If fat is mixed with flour before water added:

o Fat surrounds flour proteins and protects them

o Less gluten develops in mixture (softer, more tender and short)

· More fat used, greater amount of flour proteins that cannot be reached by water - less gluten formed (shorter result)

· More fat à shorter texture