Bread is high in sodium, as an effect of the baking process. The master formula for bread is to grind dried grain into a paste or flour, add water and yeast, let the stuff ferment and throw it on a hot surface until it dries out and stops fermenting.
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; 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:
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 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 (kneading is a continuation of mixing) 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 the necessary proteins to form gluten. Added gluten is wheat flour processed to contain this proteins, used as a dough enhancer. (Wheat gluten also is the main ingredient of the vegan food Seitan). 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.
Instant dry yeasts made for commercial bakers, rapid/quick-rise yeasts for home use, and bread machine yeasts may be the same or vary inn some way, but this is a mystery. Instant dry yeast may be 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 , rapid-rise/quick-rise and “bread machine” yeast are 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 preserves the product.
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.
Professional bakers and some home bakers express ingredient lists or recipes as formulas expressed in baker’s percentage (B%). Bakers use consistent processes to manufacture a consistent product. A formula with salt needs more yeast to ferment and rise properly. Reducing salt changes the process. 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.
Salt can be reduced , with a reduction in the amount of yeast. A few books and some internet pages unwisely suggest eliminating salt and but the same amount of yeast that would be used if there was salt in the recipe. 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 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.
Home bakers work with small amounts of salt and yeast. Measurement by weight is desireable, in theory. Few home bakers have scales precise enough. And what is the conversion?
For table salt: 1 tsp = 5.7 grams (round to 6 grams) or .20 oz. 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. Some table salt on the market in the US weighs 7 grams per teaspoon. A recipe or bread formula ought to read as referring to the conventional table salt. 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. Home bakers can normally read a recipe in terms of level teaspoons of table salt, and should adjust when using coarser (eg. kosher salt, some sea salt), or finely ground salt measured by volume.
Most sources say for instant dry yeast: 1 tsp = 2.8 grams = .10 oz. . 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.