Bread is high in sodium, as an effect of the baking process. Salt is not added to season or directly flavour bread. Salt controls yeast – it affects fermentation. Fermentation affects flavour but it also affects rise, which affects the size of the loaf and the production line; it also has a chemical effect on the taste buds (Lallamand Baking Update, Volume 2, No. 6).
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.
Archeologists have found evidence that the Nafufians, hunter gatherers in Jordan were making bread with wild cereal (grain) 12,500 BCE. Baking uses the products of many technologies. Flour is the product of grinding and milling cereal. Flour mixed with water makes dough which is baked. Dough can be fermented or leavened. Yeast consumes starches in the flour – it ferments, creating gas, which is trapped in gluten in the dough, which makes the bread rise. Bakerpedia explains:
Fermentation is a baking process in which yeasted dough rises and increases in volume and flavor is developed. Fermentation occurs when yeast converts sugar present in flour such as starch into 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 living yeast cells run out of starch, or are killed off by high temperature. If gas production goes on too long, the air cells in the dough rupture. An overproofed loaf is a lump of wet flour. In oven baking, 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 warm up the pan goes in the hot oven – before the heat kills the yeast.
Gluten “is a composite of storage proteins … found in wheat, barley, rye, oats, related species and hybrids … Gluten gives elasticity to dough, helping it rise and keep its shape and often gives the final product a chewy texture.” When flour and water are mixed and kneaded the water interacts with proteins in the flour to form strands of gluten that make the dough sticky and stretchy. Gluten relaxes in time which lets the dough flow and rise. As we read at 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.
Wheat flour has gluten already. Added gluten is a dough enhancer. (Wheat gluten also is the main ingredient of the vegan food Seitan). The added gluten changes the process. Commercial bakers know, referring again to 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.
The differences between active dry yeast and others dry yeasts: the particles of active dry yeast are larger, and coated in dead yeast cells killed in the drying process. Active dry yeast has to activated with hot, but not boiling, water. Instant dry almost never needs to be rehydrated to propogate. see All About Dried Yeast, What is Bread Machine Yeast, the King Arthur flour Ingredient Guide, the King Arthur web article All About Yeast, and the King Arthur blog post “Which Yeast to Use”. See also Commercial Yeast in Fresh Loaf Baker’s Handbook, and What’s the Difference between Active Dry Yeast and Instant Yeast. For the history of baking yeast, and the ways it has been presented, Lesaffre’s Explore Yeast pages are informative. A leading baking industry paper on instant dry yeast: Lallemande’s Update, Volume 2 # 9.
Instant yeast is smaller and activates on contact with the water in a recipe. Instant yeasts, once they activate, ferment and propogate, pick up speed and hit a peak. Some compressed and active dry yeasts have a second peak – home wine makers and home beer makers encounter this with their yeasts which have a vigorous first fermentation and a secondary fermentation. Bakers may time their bulk fermentation and final proof to take advantage of each. I found a graph on SAF Instant dry yeast gas production (in the post by Mariana January 2, 2018 in the forum Difference in Yeast Brands; see the graph with the Cyrillic text and the red line for SAF). I have not found comparison graphs for rapid/quick-rise products and other instant dry yeasts.
Books on artisinal bread baking do not distinguish quick-rise/rapid-rise yeast from instant dry yeast: e.g.: Peter Reinhart, Crust and Crumb (Ten Speed Press, 1998); Peter Reinhart, The Bread Baker’s Apprentice (Ten Speed Press, 2001); Peter Reinhart, Artisan Bread Every Day (Ten Speed Press, 2009); Robert DiMuzio, Bread Baking; An Artisan’s Perspective (Wiley, 2010). Books on artisinal baking do not mention bread machine yeast as a replacement or alternative to instant dry yeast. Reinhart said that instant dried yeast can be substituted for compressed fresh and active dry yeast for home bread baking – it is good enough for artisanal recipe uses. He came to accept that instant dry yeast should be rehydrated for artisanal breads in Artisan Bread Every Day at p. 13 (although fermentation should be slowed down with refrigeration). The accepted ratio to substitute instant for active dry in oven baking is 1 tsp of instant dry for 1.25 tsp active dry.
It is widely believed that instant dry yeasts made for commercial bakers, rapid/quick-rise yeasts for home use, and bread machine yeasts are not the same, but this is a mystery. Some instant dry yeast is dried and coated differently than some rapid/quick-rise products. See: Yeast: Dry vs. Rapid-Rise and the thread “Fast Active Fleishmann’s vs. SAF Instant” (about pizza dough). The equivalences are debated in forums like Instant Yeast vs. Fleishmann’s Rapid-Rise. Instant dry yeast, rapid-rise/quick-rise dry yeast and “bread machine” yeast are widely believed to be equivalent for bread machines.
Some recipe and baking books suggest letting the yeast and ingredients warm to room temperature. Some sources suggest that keeping yeast cold, including dried yeast, slows it down. Reinhart noted that instant yeast is potent but slow to awake in The Bread Baker’s Apprentice at p. 32. refrigeration is requies to preserve the product, this may be a factor in when it propogates and ferments.
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 meants a loaf that will rise on time, and not overproof or balloon to a size that will threaten the production line. Bread recipes may be stated as recipes or as bakers’ formulas. A baker’s formula uses percentages, but never adds up to 100%. The weight of every ingredient, other than flour, is expressed as a percentage of the weight of the flour. For 1 pound of flour 2% salt and 1% yeast means fractions of an ounce of salt and yeast. Bakers’ Percentage explained:
A formula scales; the same proportions are used to create 1 or 1,000 loaves of bread. A formula with salt needs more yeast to ferment and rise properly to the right size to fill baker’s loaf pan. Reducing salt in bread formulas leads changes the process. Professional bakers use up to 2 pounds of salt (and about 1 pound of yeast – the ratio depends on fresh, active dry, instant dry) per 100 pounds of flour. This works out to .3 ounces (8.5 grams, or 8,500 mg.) salt to 3 cups (5 ounces per cup) of flour. A normal loaf of bread has 3,400 milligrams of sodium per loaf- several hundred milligams per slice or serving. Professional bakers use consistent processes to manufacture a consistent product.
Baking with salt requires more yeast.
Salt can be reduced in a recipe/formula, with an adjustment in the amount of yeast. A few books and some internet pages suggest eliminating salt and using 1 to 1.5 tsp of yeast for 3 cup of flour – which is what what would be used if there was salt in the recipe. I don’t think this is right. Every reduction in salt in a bread formula has to be balanced with a reduction of yeast. The accepted method is reducing yeast by the same percentage as salt. Please Don’t Pass the Salt has recipes for quick breads, yeasted breads and a note on the general adjustment for yeasted bread recipes.
Artisan bread baking writers suggest that adjusting the salt in recipes/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 approach warns the aspiring baker that salt is important to baking what consumers and food critics regard as good bread. This approach does not help much for someone avoiding sodium. It is easy to get to 50%. It is possible to go further if final proofing can be extended to let the dough ferment and rise longer. Conversely, working in the kitchen, a baker may detect and arrest an active fermentation by knocking down the dough or getting the loaf in the oven.
The size of the salt crystals matters for solubility, which can affect the way the distribution of salt in the dough, and effect of salt on yeast. Density, as such, doesn’t matter when a professional baker is adding salt by weight. Home bakers using measuring spoons need to think about density. Home bakers can normally read a recipe in terms of level teaspoons of table salt, and adjust when using coarser (eg. kosher salt, some sea salt), or finely ground salt. For table salt: 1 tsp (volume) = 5.7 grams or .20 oz. (weight). Home bakers trying to go by weight have to find the right conversion. The conversion should be 1 tsp of table salt = .25 oz . = 6 grams. Peter Reinhart, The Bread Baker’s Apprentice (Ten Speed Press, 2001) says on p. 28 that 1 tsp of table salt = .25 oz . This conversion may have taken some rounding – few home bakers have scales precise enough to go down to that level of precision.