The Science of Baking - Flour Power!

September 3, 2018

 

It's that time of year again when the Great British Bake Off is back on our TV screens and the nation dons it's collective pinny and heads to the kitchen, eager to have a go at making some of the masterpieces they see on the screen. It's also the time when I get asked more questions than at any other time of the year. It usually starts off something like this: "Who do you think will win bake off? You should go on it. How do you ... (insert question) ..." Or "Did you see bake off the other day? Actually, you will probably know this, why don't my ...(insert name of baked goods)... turn out like that?"

 

As you have probably realised by now, I love to bake!  Big cakes, small cakes, biscuits, bread, puddings and anything in between, it doesn't really matter, there's nothing I like more than messing around in the kitchen creating edible treats.  And I have had my own share of failures too, or caketastrophies, as I like to call them.  This is usually because something has gone a bit awry during the baking process, because baking is a science and if you change one little thing, the unexpected can happen.  Sometimes this is a happy surprise but it can also be an unmitigated disaster!

 

I have learnt a lot over the years, trying different recipes, testing and tweaking and with the new series of GBBO on TV I thought it would be fun, if not educational, to look at the science of baking.  Heck, it might even be useful to some of you!  In this post I am starting with one of the staples of any baker and that is flour.

 

There is evidence that man has used wheat as food for thousands of years.  In Egypt, tombs along the Nile contain ancient murals which show wheat planting and harvesting, the grinding of flour and making of bread, and in 1948 archaeologists discovered an ancient village in Iraq where they found two different types of wheat similar to those grown today.  Wheat is still eaten in primitive forms in many parts of the world and similar crude tools to those used thousands of years ago can still be seen in use today.

 

Wheat found in the excavation of ancient cities often appears carbonised as though the husk had been removed by heat.  Heating the grain makes the glumes easier to rub off.  Other cereals, rice, corn and maybe some varieties of early wheat could be popped, like what we know today as popcorn.  The moisture inside the hard outer coat would turn to steam in the heating process to explode the grain glumes.

 

Wheat flours, the most commonly used flours, are milled from the wheat berry.  The berry consists of three parts - the outer hull, or bran; the small germ, or embryo, inside; and the endosperm, a starchy material that feeds the embryo.

 

Today, so many foods contain wheat that it is often an unnoticed part of our diet but bread, of course, is the most familiar wheat product.  There are many different types of flour available and when a recipe requires flour we should ask ourselves "does the choice of flour make much difference to baking?"  The answer, of course, is yes.  The right flour, combined with practical skill, will give you the best results.  Flours vary in composition and, broadly speaking, are defined according to the type of wheat from which they are milled.

 

Wholemeal or wholewheat flour contains the whole of the wheatgrain (including bran and germ) with nothing added or taken away.

Wheatmeal or brown flour usually contains about 85-90% of the wheatgrain.

White flour usually contains about 72-74% of the wheatgrain.

 

White flour, including strong bread flour and plain or all purpose flour, consists of the milled endosperm, with the bran and germ removed.  Plain flour is milled to be used in a variety of ways and is made with a combination of hard and soft wheats.  Strong flour is milled specifically for bread and is made only from hard wheat.

 

Wholemeal and brown flours give variety and colour to baking but goods baked with them have a limited rise and a closer texture than those made with white flour.  It can also have a slightly bitter flavour and for these reasons many wholemeal breads are made with a combination of wholemeal and white flour.

 

A protein present in the flour, glutenin, when combined with water forms gluten, which is stretchy and elastic.  When goods containing gluten are cooked, the water inside is converted into steam which expands, blowing up the gluten like a balloon, forming air pockets.  As the goods continue to cook, the gluten sets, trapping the air, and it is the gluten framework which forms the structure of the product.

 

The quality and quantity of gluten produced by a flour are both important.  Tough gluten is hard to blow up while soft, sticky gluten blows up easily but collapses quickly.  For the best quality bread, a good elastic gluten is needed which will blow up into large balloons but will hold its shape until set by the heat of the oven.