Flour is the product of grinding and milling cereal (grain). The point of harvesting and milling grain is to preserve the starches, to be eaten and metabolized into glucose. When flour is mixed with water, starches dissolve. Gliadin and glutenin are insoluble proteins in grain and in flour. When water is added to flour, these proteins bond into strands and sheets of gluten “a composite of storage proteins … found in wheat, barley, rye, oats, related species and hybrids … ” Cereal scientists and commercial bakers know, referring again to Bakerpedia:
Consisting of mainly gliadin and glutenin, wheat gluten is unique among cereal proteins based on its ability to form a cohesive and viscoelastic mass. This rheological property makes it a dynamic material that is able to grow and keep the gasses within the dough during extended fermentation periods. The viscoelastic nature also provides the oven spring (increase in height due to the expansion of gasses) that we see in the oven.
Gluten gives elasticity to dough, helping it keep its shape and often gives the final product a chewy texture. Gluten relaxes in time which lets the dough flow and rise. As we read at Bakerpedia:
Excessive use of wheat gluten would result in drier doughs that have a hard time with pan flow, and a higher than normal oven spring.
Gluten will form when water is added to flour. Bakers knead dough, stretching and folding it on itself, repeating the motion for several minutes. This structures the gluten. A baker can pause after mixing or start kneading, or pause during kneading. Kneading pulls the gluten into a network of micro balloons. The dough should be tenacious and elastic to hold together, extensible to stretch, and viscous to flow. A professional baker will probably use a mechanical mixer; many home bakers may have one. A mechanical mixer or stand mixer uses mixing arms, a paddle or a spiral dough hook in a circular or elleptical motion. A mixer has a range of speeds. The baker uses a slow speed to mix the ingredients and a higher speed to knead.
Whole wheat and bread flour weigh the same amount per unit of volume; bread flour milled to US and European standards (and Canadian All-Purpose) from wheat has more of the proteins that bond to form gluten. Dough made with each flour is mixed, kneaded and handled differently.
The proteins can be extracted and dried into vital wheat gluten, a powder used as a dough enhancer.
At some point the dough has to be left to rise. Yeast consumes some of the starches – it ferments, creating gas, which is trapped in gluten in the dough, which makes the bread rise, after the dough has been kneaded. Bakerpedia explains:
When yeasted dough ferments rises and increases in volume, and flavor is developed. Yeast converts starch in flour into sugar, carbon dioxide and ethyl alcohol. CO2 gas is trapped by gluten proteins in the flour which causes dough to rise. Fermentation results in a light and airy crumb.
The yeast propogates. Propogation and fermentation accelerate until the yeast cells run out of starch, or are killed off by high temperature. The dough rises in 2 or 3 stages: bulk fermentation, and intermediate and final proof. Dough is knocked or “punched” down to release gas at the end of the bulk fermentation and again when the loaf is shaped. The dough rises again in the baking pan and springs when yeast warms up after the pan goes in the hot oven, before the heat warms the dough and kills the yeast.
Modern professional bakers work with hundred of kilograms of flour and water. Professional bakers have control over how long to mix, rest, bake and over oven temperature. Ingredients are mixed and kneaded in large industrial mixers, fermented, put into pans and put into ovens, turned out and packaged. The dough goes into pans in small irregular lumps. It has to rise and flow to fill the pan, spring when pans go in the oven, but not spring above the limited headspace of the pan. Professional bakers may use 10-15 minutes of “intensive mixing” – the mechanical mixing of yeasted white flour dough was dominant in professional bakeries for French loaves until Raymond Calvel devised the hybid style in the 1960s. Intensive mixing develops gluten in white flour rapidly. Home bakers with stand mixers use slower speeds due to limitations of machinery (see the stand mixer review by America’s Test Kitchen in print and YouTube) or to use a hybrid, modified or improved mixing method. Overmixing is a risk for professional bakers using industrial mixers. Machine mixing can stretch dough too much or too often, breaking the gluten strands. An overmixed dough cannot hold the gases, and will not rise. Intensive mixing may affect a loaf with effects short of the complete failure caused by overmixing. Home bakers can have the same problem. A variety of mixers are available to the home baker:
- Food processors can mix dough, although a food processor might only handle 3 cups of flour, and may only have one speed – very fast. The mixing time may be less than a minute. Some food processors have a dough speed and/or special blade to mix dough. The risk of overmixing dough in a food processor is well recognized.
- A home stand mixer can handle several cups of flour, at low-medium speed settings. The power output of a Kitchen Aid stand mixer with a 5 quart bowl may be 325 watts. Larger stand mixers may output 800 watts. A Bosch Compact Kitchen Machine may output 400 watts into its dough hook in its stand mixer configuration. They have to be used at the right settings and for a short time.
Salt affects the development of gluten. It affects chemical bonds in amino acids in proteins in flour that has been exposed to mixed with water. It makes the gluten more tenacious and elastic. Salt controls yeast which affects fermentation. Fermentation affects flavour but it also affects rise, which affects the size of the loaf and the production line. Salt has a chemical effect on the taste buds (Lallamand Baking Update, Volume 2, No. 6).
Mark Kurlansky’s excellent book Salt: a World History (2002) tells of the use of salt to bake bread in Egypt (3,000 BCE), The production of salt may have started about 8,000 years ago. Salt is a standard and necessary ingredient in most formulas and recipes. The right ratio of flour to salt and yeast means a loaf that will rise on time, and not overproof or balloon. The bottom of the dough is supported. The sides may be confined by the walls of a pan. The loaf should crown to form a dome. A few bread styles, such as Tuscan bread, are made without salt. Salt is part of the process for most bread sold by grocery stores and bakeries large and small. Bread is high in sodium, as an effect of the baking process.
Salt can be reduced, with a reduction in the amount of yeast. Some books and internet pages unwisely suggest eliminating salt and but list the same amount of yeast that would be used if there was salt in the recipe! This will may bake or collapse. In a bread machine, the dough will balloon and may or collapse before it overflows the pan.
Every reduction in salt has to be balanced with a reduction of yeast. Please Don’t Pass the Salt has recipes for yeasted breads and a note on the general adjustment for yeasted bread recipes. Artisan bread baking writers suggest that adjusting the salt in formulas leads to unsatifactory results – e.g. Peter Reinhart, Artisan Bread Every Day (Ten Speed Press, 2009) at p. 15 suggests not reducing by more than 10%. This warns that salt affects gluten but does not help someone avoiding sodium. It is easy to get to 50% and 33%. The most precise way of measuring is by weight.
|Goal||Reduction||Use Salt||Use Yeast|
Professional bakers and some home bakers express ingredient lists or recipes in baker’s percentage (B%) to use consistent processes to manufacture a consistent product. Professional bakers may use 2 pounds of salt and .77 pound of instant dry yeast per 100 pounds of flour. The B% for salt is 2%; instant yeast is .77%. This works out to .3 ounces = 8.5 grams = 8,500 mg. salt per 3 cups (15 ounces) of flour. A normal loaf of bread has 3,400 milligrams of sodium per loaf – several hundred milligams per slice or serving. Home bakers work with small amounts of salt and yeast. Bread machines use very small amounts for single loaves.
Measurement of salt and yeast by weight is desireable for home bakers and bread machine bakers. Few home bakers have scales precise enough.
Conversion? The great majority of recipes refer to standard ground table salt. For table salt: 1 tsp = 5.7 grams (round to 6 grams) or .20 oz. Some fine crystal table salt on the market in the US weighs 7 grams per teaspoon. I am aware of other information, but do not pay attention to this information unless the recipe I am referring to has used a coarse or fine salt:
- America’s Test Kitchen/Cooks Illustrated The Science of Good Cooking (2012) lists several brands of kosher salt and sea salt and compares them to table salt, suggesting that Morton’s brand is the standard for table salt at 1 tsp = 7.15 g.
- Peter Reinhart, The Bread Baker’s Apprentice (Ten Speed Press, 2001) says on p. 28 that 1 tsp of table salt = .25 oz which converts to 7 grams.
The size of the salt crystals affects solubility, which can affect the distribution of salt in the dough, and effect of salt on yeast. Density, as such, doesn’t matter when adding salt by weight. A gram of kosher salt works as well as a gram of table salt for baking bread.
Most sources say for instant dry yeast: 1 tsp = 2.8 grams = .10 oz. This is what I use, and verify with the yeast I use. Again, there is contradictory information in some publications. Peter Reinhart, The Bread Baker’s Apprentice (Ten Speed Press, 2001) says on p. 28 that 1 tsp instant dry yeast = .11 oz which converts to 3.1 grams.
Commercial bakers use chemical leaveners for some bread. Home bakers use baking powder and baking soda for corn bread, soda bread, cakes and other baking. Baking powder is baking soda mixed with cream of tartar. Kraft Foods Magic Baking Powder does not provide Food Facts on the labels of small jars in Canada. The published information is that 1 tsp has 300 mg. of sodium. Substitutions for baking powder involve 1/4 tsp of baking soda plus some acid (e.g. vinegar, cream of tartar) for each tsp baking powder. Baking soda is sodium bicarbonate. It has 1,259 mg. of sodium per teaspoon, which explains the food facts for baking powder. The science of substitution for baking soda and baking powder is to use potassium bicarbonate, which is the key ingredient of Featheweight – not an widely available (i.e. in grocery stores) product. It is available as a supplement but has a list of side effects and do not use if taking medication warnings. Please Don’t Pass the Salt has recipes for quick breads, and suggestions on low sodium “baking mixes”.
“Natural” products that that might trap CO2. Some recipes for some baked goods suggest this is possible e.g. whipped egg whites.