Unlike the oilseed crops, the cereal grains contain only a small portion of natural oils or fats. In wheat and rye it is only about 1 – 2%, while it is considerably higher in barley and oats, where it can be as high as 6 – 7%.
The well known lipids are the ones that comprise the highly nutritious oil that is part of the germ, and there are lipids which are playing important roles in both the endosperm and cells of the inner bran layers. They are described scientifically as being types of fatty acids. Of course the whiter flours barely contain any germ oil since their meticulous sieving removes nearly all traces of germ, aleurone layer, and bran, but other lipids will be present in all flours since they play an important role in protecting the interior of each cell, forming a barrier between the inner portion of the cell and its membrane which is its protective coating through which the nutrients come inwards and the waste is flushed outwards. In this role the lipids are associated more with the protein cells than the starch.
Given that natural oils and fats are such a tiny fraction of flour, when we make rich breads we need to add fats to get the special effects we are looking for. Butter is the superior baking fat for stability and flavour, and it is incorporated best into dough in its solid form rather than melted by the application of heat. Slightly soften the butter by giving it some time out of the refrigerator, allowing it to approach ambient temperature rather than melting it. Most bakers would agree that butter is their favourite fat, but they lament its price which inevitably makes the goods expensive. I add it to the stollen dough at one-fifth of the flour weight. Goods as rich as croissants have it as half the flour weight.
The traditional solid bakers’ fat in the British Isles that used to be the universal bread fat is lard, but sadly today it is very difficult to find attractive lard made by a butcher. The lard of today is industrially made with an astonishing array of chemical additives.
Vegetable oil goes well in dough, and has gained a wide appeal since many consumers are vegetarians, or simply seek to avoid animal fats. I always add veg oil to any dough that is described as wholemeal, brown, or “coarse”. The reason for this is that bran, always present in the darker breads, is continually absorbing moisture, causing the baked bread to dry out and go stale more quickly. The staling process can be off-set to a small degree by the addition of oil or fat which gets in the way of the starch cells’ release of water as they revert to their natural shape. The guidelines for use of oil in dough would be to use at least double the salt weight – say 3 – 4%.
It is important to add the fat late in the dough-making process. If you add it at the start it will inhibit the formation of gluten since the flour particles when coated by fat cannot properly absorb water to form the gluten. Rubbing the fat in early is the preserve of short crust pastry, or a “cakey” type of bread like West Country saffron dough cake. When the fat is added at the correct time – late in the kneading – it actually enhances the dough by lubricating the gluten strands.
Fat will always be in the recipe for rich and delicate dinner rolls, as well as sandwich bread which needs to be able to be sliced thinly and is unattractive when it begins to stale. On the other hand, there are lots of white breads that do not need fat enrichment when they are made with strong flour of a high protein strength which holds its dough moisture when baked, as well as sourdough breads which need no added fat since their acidic chemistry gives a long shelf life.