Tip of the Week: Why is Flour Composition So Important to Breads and Rolls?

When you talk about ingredients that play an important role in bread and roll products, wheat flour is the single most important and most basic ingredient. It is the dominant ingredient in bread and rolls. Flour’s main function is to provide structure. The major components of flour that provide structure for breads and rolls are starch and proteins. Wheat flour is primarily carbohydrates in the form of starch averaging about 70% of the total flour. Total protein content in a typical bread flour will range between 10.5 to 13%. So you can see that starch and proteins make up the major proportion of the flour’s composition with moisture, hemicellulose (pentosans), sugar, cellulose, lipids, fiber, minerals, and vitamins being the remaining components of the flour’s composition.

Bread flours are typically milled from hard wheats (Hard Red Spring, Hard Red Winter, and Hard White) because of the protein and protein quality which hard wheats possess. Protein content for bread flour is usually between 10.5-13%. In the minds of bakers and flour millers, much of this protein equals gluten-forming protein. The key gluten-forming proteins in wheat flour are glutenin and gliadin proteins. When glutenin and gliadin are hydrated and mixed with water they form gluten. While it is true that most of the protein in wheat flour is gluten forming protein there are some non-gluten forming proteins such as albumins, globulins and proteoses. Normally the higher the protein level of the flour the better the expected quality of the flour, but quality does not always increase with protein quantity. Protein quality is measured by the ability of the gluten to expand properly and retain gas in such a way to produce a quality product.

Wheat flour owes its value to bread making to the unique way in which the gluten forming proteins combine with water in mixing to form gluten. The glutenin protein gives the dough the gas retaining ability with its elasticity. Glutenin is the main protein responsible for the viscoelastic rheological characteristic of a properly mixed dough. The gliadin protein gives the dough the ability to be sheeted with its extensibility. The baker will look for that proper balance between the elasticity and extensibility of the dough to determine proper dough development.

The composition of wheat flour is mostly starch. The starch may be either damaged starch or undamaged starch. Damaged starch in a bread flour will typically be in that range of 5 to 11% of the total flour while undamaged starch will make up to around 65% of the total flour. The damaged starch is desirable in products produced with a fermentation system since natural occurring enzymes called amylases convert the damaged starch into dextrins and sugars which the yeast uses as a food source in fermentation. Damaged starch and proteins absorb water in the dough becoming fully hydrated while the undamaged starch cannot become fully hydrated until the baking process. Undamaged starch will become fully hydrated when the starch crystals in the presence of water are exposed to high temperatures (140-180°F or 60-82°C). The starch molecules will swell at this point and become fully hydrated forming a firm gel. This is referred to as starch gelatinization and once it is complete the structure of the bread or roll is set.

When looking at flour quality factors, we are watching how the flour performs in the mixer and fermentation room. How is the mix time and/or fermentation time affected? Is it a strong or weak flour? What is the water absorbing capacity of the flour? With flour being the predominant ingredient in a dough it plays a major role in determining dough absorption. Flour plays a big role of impacting the finished product characteristics of bread and rolls. Loaf/roll volume, symmetry of loaf/roll, crust color, grain, crumb color, texture and taste are all impacted by the flour used to produce the bread or roll. The gas retaining ability of the flour gives us loaf volume in the proof box as well as strength in the oven. The absorption capability of the flour will impact the dough’s consistency which plays a major part in how we make up the product. How well this make-up is done will be reflected in the symmetry of the finished product. Higher protein levels in flour will result in darker crust color as a result of Maillard Browning Reaction. Darker crust colors will give a stronger taste of the product. Grain and the resulting texture is impacted by the gas retention ability of the gluten as well as the product’s cell structure. The resulting crumb resiliency is also a result of the flour’s protein. This will have an effect on the eating quality of the finished product.

So as you can see, flour is a very important ingredient in the production of bread and rolls. A bread baker’s thorough knowledge of flour composition and functionality is important when troubleshooting product problems, problem solving processing issues or developing/enhancing bread and roll products.

 

 

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