2/4 Shortening and Bread Fats

Self-test Questions (Shortening)

Question 1

What are the main sources of edible fats and oil?

The main sources of edible fats and oils are,
Vegetable Fat
Animal Body Fat
Milk Fats
Fish and marine animal fats

These fats and oils are extracted from their natural source by heat, by dissolving them in solvents (rendering) or by pressure. Fats are used in bread production as an overall lubricant.

Question 2

Describe the difference between a fat and an oil.

There is no chemical difference between a fat and oil. Each substance contains carbon atoms, hydrogen atoms and oxygen atoms. Both fats and oils are insoluble in water but soluble if fats solvents. However, a product that is normally liquid at room temperature is referred to as an oil and one which is normally solid at room temperature is referred to as a fat.


Question 3

Why are the mineral oils inedible?

The human digestive system cannot breakdown mineral oils and they pass through the body unchanged. As passing through our body they absorb or leach out of the fat-soluble vitamins from other foods in the digestive system, which are then lost resulting in poor nutrition. As a result the use of mineral oils in food is banned.

Question 4

Explain the advantages in using margarines, as compared to other types of fats.

Modern margarines have a distinct role in the baking industry and are highly complex with specific applications. While butter is considered the ideal edible fat, Margarines are more stable, less prone to rancidity, have a longer shelf life and do not usually require refrigeration, whereas the like of butter does.

Question 5

Describe three ways that fats can spoil.

One way is Oxidation; fats will react with oxygen in the air, particularly the presence of UV light. When oxidation occurs the molecules of the fatty acid are released from their bonds, and so the two constituents of fat (glycerol and fatty acids) separate. Oxidation results in rancid fat.

A second way fats can spoil is Enzymic Breakdown, as edible fats are sourced from animal and vegetables, the presence of enzymes is necessary for the living cells to produce them and store them. These enzymes accelerate the chemical reactions of fats by their presence.

The third way fats can spoil is by Mould, moulds are micro organisms which require moisture for growth. Thus in a pure fat mould will not grow. However, all margarines contain some additives and these provide sufficient food and moisture for mould growth, even at refrigeration temps.



Question 6

Name the three elements that edible fats are made up of.

Margarines
Shortenings
Hydrogenated Fats

Question 7

What other additives are sometimes added to special bread shortenings and fats?

Shortenings are usually 100% fat, however, some modern bread shortenings contain emulsifiers and crumb softening additives as well as sugar or malt supplements for enhanced crumb and texture qualities. Emulsifiers help disperse ingredients more evenly throughout the dough. Other additives can include,
Mono and di-glycerides of fatty acids
Sodium Stearoyl Lactylate
Calcium Stearoyl Lactylate
Lecithin
Sorbitans and polysorbates

Question 8

List the effect of fats on the final loaf characteristics.

Keeping Qualities (preservative)
Crumb Texture and Colour
Crust Character
Volume
Slicing
Dough Handling Properties