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• generalize a description of various bread products.
  
• explain the purpose of each step in a typical yeast bread product.
  
• produce a typical yeast bread products.
  

Preparation of the "classic" loaf of white bread can be as simple as combining the basic ingredients: flour, water, and yeast, kneading, fermenting, proofing and baking. However, each ingredient's role and contribution of each step of the process preparing breads can be confusing and difficult. The complexity increases because there are over 200 types, not including specialty breads [Pomeranz, 1983].

Wheat breads are divided into four classifications:

Although a complete understanding of each of these doughs is not reasonable for the beginning student, some understanding can be obtained by exploring the main structural components, the flour proteins, starch, leavening, and baking.

As early as 1912, reports on factors affecting the quality of bread were reported. Dudley (1912) indicated "The quality of flour for bread making depends upon the percentage of gluten in the flour, and the proportion of gliaden and glutenin in the gluten." There is no doubt that this development of gluten in the dough system is critical. A dough system for yeast bread may be made by mixing flour with water. Other ingredients such as yeast, salt and sugar are added for leavening, flavor or other quality factors in bread.

Of the predominant wheat flour constituents, the gluten-forming proteins, both kind, quality and amount are of major importance. The starch fraction is of secondary importance in its contribution to the dough-making and baking properties. Corn, soy and rye flours do not have these proteins to form gluten during mixing. Gluten is formed from the two wheat flour proteins, gliadin and glutenin, the presence of water and some mixing.

During the mixing portion of preparation, the gliadin and glutenin form gluten. The particles stretch, stick to each other, and become elastic. When the dough is mixed the gluten fibers are parallel and cross-bond to form the elastic but strong structure. During the latter stages of mixing, air is incorporated and subdivided. It was been hypothesized that hydrated gluten strands contract around air bubbles and, with proper mixing, supply the dough with well-distributed air bubbles. Good bread texture depends to some extent upon the uniform distribution of such hydrated, aerated gluten nuclei.

One can not disregard the fermentation phenomenon in the development of the typical bread product. Briefly, this process will "temper" the gluten to enhance its elastic and tender cell wall structure. The reaction produces the carbon dioxide which serves to initiate expansion of the cells developed during kneading and mixing. The fermentation process also produces alcohol which not only tenderizes the gluten structure, but it furnishes the vapor for the initial oven spring during baking. Most importantly, the fermentation process furnishes a substantial part of the odor and flavor of the large portion of white breads and some of the varietal breads.

The typical loaf of white pan bread, should have the following quality characteristics.

The above discussion refers to the "typical white" loaf of bread. The market place has increasingly become open to varietal breads. As one becomes more experienced in the preparation of basic baked products, it is expected that there will be branching out into this area of breadmaking.

Standard White Yeast Bread

Ingredients		Percent Formula		Metric Formula		Measure Formula
Flour		100%		~168 g		~1.5 cups
Milk		70%		118mL		1/2 cup
Sugar		4%		6 g		1/2 tbsp
Fat		4%		6 g		1/2 tbsp
Salt		2%		3 g		1/2 tsp
Yeast		4%		7 g		1 tbsp scant

Directions for Straight Dough Method

1	Preheat oven to 200C(400F). Be sure to check the oven temperature with a thermometer.
2	Scald milk by heating to 92C for 1 minute. If a "skin" is formed on the surface, it is "done". Add sugar, fat, and salt.
3	In a small custard dish put active dry yeast to soak in 2 tbsp (30 mL) of water at 45C( 110-115F).
4	Cool milk to 27C. Add the hydrated yeast.
5	Add half the flour, stir until the batter is smooth and free from lumps.
6	Add more flour (so that the dough is not too sticky to knead.) Stir thoroughly. Avoid extra flour if the bread is to have fine grain.
7	Put 1 tsp of flour onto a dry board. let dough rest for three minutes. Roll dough around in the flour lightly to coat the surface. Record the start of kneading time. Then knead (fold gently with firm, short strokes) for 8 to 15 minutes. Rotate the dough a quarter turn after each stroke or two. The dough should feel smooth and velvety with small barely discernible white "blisters" on the surface when completed. Record completion of kneading time.
8	Place warm water (27C) in the bottom of a double boiler. Place dough in the top of the lightly greased double boiler and cover. Record start of fermentation time. let dough rise until nearly double in bulk and/or the dough is no longer elastic when poked with a finger. Record completion of fermentation time.
9	Punch down gently and shape into loaf. Place into the lightly oiled half-pound loaf pan.
10	Cover loaf pan and let rise at 27C until approximately double in bulk. When light, the dough will just barely keep the imprint of your finger when gently touched. Record start of baking time.
11	Bake loaf at 200C (400F) for 20 to 25 minutes
12	Remove from the oven and place on cooling rack. Record completion of baking time.

The "typical" yeast bread product has been defined by the American Association of Cereal Chemists. Reality is that very few loaves of bread meet this standard. The increase in varietal and specialty breads has been part of the reason for this deviation. The other reality is simply that the "standard" loaf of bread is not made very much anymore as ingredients and processing/preparation methods have changed. Following are some representative loaves of bread. These are not necessarily typical.

What gives bread its light, fluffy texture?

A = left; B = middle; C= right

Evaluating the image, assume that that these three loaves were baked in the same oven for the same length of time. Why do you hypothesize that these loaves differ in color?

What is the affect of too much fermentation? Too little sugar? on yeast bread quality?

Updated: Wednesday, October 24, 2007.