Salt and bread making

Salt is one of the four essential ingredients in making bread, along with flour, yeast and water. Nothing more is needed, although often a lot more is added.

Salt is listed in all the recipes. Only one bread I’ve ever read about is salt-free (a Tuscan specialty mentioned in William Alexander’s book, 52 Loaves).

We tend to assume salt is simply for flavour, but it is also part of our basic biology:

I find it easiest to think of salt as one half of the body’s water-regulation system, the other half being potassium. The membranes of every cell in the body allow water to flow through in direct proportion to how much sodium and potassium are present in the immediate area. Too much or too little sodium in the body affects everything from digestion to blood pressure to brain function.

Since proper sodium levels are so important, the body uses the kidneys to maintain a precise balance. The system is very efficient, which means that if you eat more sodium than the recommended daily allowance, you’ll simply excrete whatever you don’t need (within reason). That also means that we tend to crave more salt than we actually need to eat, which might explain its flavor-enhancing properties.

Salt, as the site above tells us, suppresses bitter flavours, which means some foods taste better salted (at least in my cultural background, which favours sweet and salty over sour and bitter). Because it suppresses bitter, which in turn suppresses  sweet and sour flavours, these flavours come across as stronger in the presence of salt.

Which suggests that a bread with a sweet factor – say raisins, coconut or cranberries – can have a higher salt content than a plain bread, because the salt will enhance the sweetness. So less sugar, more salt? (Okay, I don’t cook with processed sugar because I try to avoid it in my diet…)

Read this food science piece in Nature about salt, food and flavour. Very interesting.

Taste and flavour are not quite synonymous, as the National Institute of Health reminds us:

Taste and flavor are terms that are often confused. The word “taste” has two meanings, one technical and the other as commonly used in the English language, which encompasses the larger concept of flavor…

The sense of taste, one of the five major senses, is defined based on anatomy. In mammals, it is the sense subserved by taste receptor cells located primarily on taste buds in the oral cavity. These taste receptor cells are innervated by branches of the seventh, ninth, and tenth cranial nerves that synapse first in the brainstem prior to sending messages to other parts of the brain…

Virtually all foods and beverages impart sensations in addition to taste. For example, a complex food such as soup not only has taste properties (e.g., it is salty, sour, or sweet) but also has volatile compounds that give it its specific identity (e.g., pea soup compared to potato soup), and it may also have burning properties, such as those caused by hot peppers… In common parlance, the entire sensation elicited by this food is called its “taste.” However, most scientists would instead use the term “flavor” to refer to this total sensation, and that is how it will be used here. It should be noted that many also include the texture of a food as a component of flavor. Taste molecules such as salt can influence flavor in many ways, some of which are described below.

Of course, salt plays other roles in the baking, fermenting and gluten development stages. According to the Wild Yeast blog:

• Salt affects dough texture, making it stronger and less sticky, as the commenter noticed.
• Salt reduces oxidation of the dough during mixing. Oxidation causes the degradation of carotenoid pigments in the flour that contribute to flavor and crumb color.
• Salt regulates yeast activity, causing fermentation to progress at a more consistent rate.
• Salt affects shelf life. Because it attracts water, it can help keep bread from staling too quickly in a dry environment. However, in a humid environment, it can make the crust soggier.

King Arthur Flour – a great source of information for bakers at all levels of experience – expands on this with a lengthy description:

Salt provides flavor. Bread baked without salt will have a flat and insipid taste. On the other hand, bread made with an excess of salt will be unpalatable. Generally, the correct amount of salt in bread dough is 1.8 to 2% of salt based on flour weight (that is, 1.8–2 pounds of salt per 100 pounds of flour). The lack of ability to coax fermentation flavor from bread sometimes causes the baker to use an excess of salt. But it should be kept in mind that, while salt provides flavor, it is not a substitute for the fine flavor of well-fermented flour, and the role of salt is to enhance, and not take the place, of true bread flavor.

Salt tightens the gluten structure. The tightening gives strength to the gluten, enabling the dough to efficiently hold carbon dioxide, which is released into the dough as a byproduct of the yeast fermentation. When salt is left out, the resulting dough is slack and sticky in texture, work-up is difficult, and bread volume is poor.

Salt has a retarding effect on the activity of the yeast. The cell wall of yeast is semi-permeable, and by osmosis it absorbs oxygen and nutrients, as it gives off enzymes and other substances to the dough environment. Water is essential for these yeast activities. Salt by its nature is hygroscopic, that is, it attracts moisture. In the presence of salt, the yeast releases some of its water to the salt by osmosis, and this in turn slows the yeast’s fermentation or reproductive activities. If there is an excess of salt in bread dough, the yeast is retarded to the point that there is a marked reduction in volume. If there is no salt, the yeast will ferment too quickly. In this sense, the salt aids the baker in controlling the pace of fermentation. Nevertheless, we should note that a careful usage of yeast, control of dough temperature, and the type, maturity, and amount of preferment used are better tools for fermentation control. Salt quantity, as we have noted, should stay within the 1.8–2% range.

Salt indirectly contributes to crust coloring. This attribute is a result of the salt’s characteristic of retarding fermentation. Starch in the flour is converted into simple sugars by the amylase enzymes, and these sugars are consumed by the yeast as it generates fermentation. Since the salt is slowing the rate of the sugar consumption, more of what is known as residual sugar is available at the time of the bake for crust coloration. In the absence of salt, the yeast quickly consumes the available sugars, and the crust on the baked bread is pale and dull.

Salt helps preserve the color and flavor of flour. The carotenoid pigments, naturally present in wheat flour, are responsible for giving flour its creamy color and wheaty aroma. It is extremely important for the baker to understand that an unbleached flour, such as all of King Arthur’s flours, contains a complete profile of carotenoids, and that bleaching flour destroys these fragile components. For this reason alone, choosing a high quality unbleached and unbromated flour is preferred for all breadmaking. Other than bleaching flour and thereby destroying the carotenoids, overoxidizing of the dough during mixing, which occurs when a dough is mixed too intensively for too long, also destroys them. Salt has a positive effect on the preservation of carotenoids, because dough oxidation is delayed in the presence of salt. For this reason it is preferable to add salt at the beginning of the mix. In this way, salt benefits the eventual flavor of the bread by helping to preserve the carotenoids during the mixing of the dough. When salt is added during the later stages of dough mixing, it can be detrimental to the carotenoids, which may become overoxidized.

Most recipes I’ve encountered ask for 2-2.5% salt by weight (calculated as a percentage of the flour’s weight, not the overall weight of the mix). Some recipes may call for as little as 1% and others top 4%.(For the record, I was unaware of the term ‘hygroscopic’ before I read that… that piece leads to another topic: the apparently tenuous balance between oxidizing via mixing to promote yeast growth and over-oxidizing that destroys carotenoids…)

My latest bread was baked with a recipe that called for 10g of salt with 310g of flour, or about 3.2%. However, when the 190g of flour in the poolish is added in, that ratio falls to 2%. I further reduced it to about 6g (my kitchen scale isn’t very accurate for amounts under 10g), or about 1.2%

To me, the higher ratios taste a tad too salty. Since we don’t salt our foods normally when cooking, and look for low-sodium foods when shopping, my tastes may have been conditioned to find what many people consider “normal” salt levels too high. I’m looking for a comfortable balance between taste and effect.

The National Institute of Health says, rather poetically:

A critical attribute of salt taste is its hedonic or pleasantness dimension. For many foods, adding salt increases the liking for that food up to a certain point, after which more salt reduces its pleasantness (palatability). This inverted “U” function of added salt can be used in formulating foods, by testing the acceptance of different salt concentrations with many consumers.

I like that notion of hedonic taste sensation: marked by pleasure; hedonistic. It puts bread into the same flavour-rich category as red wine, tequila, sushi (and wasabi), ginger, hot sauce, strong cheese, garlic, curry… the sensation of a bread fresh from the oven is certainly a hedonistic experience. Makes one think of a Jamaican resort where clothing is optional…

Andrew Brown wrote in The Telegraph that a single slice of commercial bread has more salt in it than a bag of potato chips:

A typical slice of our daily bread may contain as much salt as a packet of crisps, the Telegraph’s science correspondent Nick Collins reports today. And a pain de campagne from Paul, the bakery chain, contained 2.83g of salt in every 100g – which is apparently more salt than is found in seawater.

(This, by the way, links to a recipe for a Lammas bread, which I intend to try soon… it uses only 6g of salt, which is 1.4% of the total flour, and only 1.15% of the total with the wheat kernels included). I clearly don’t want bread as salty as your typical potato chips (which sparks the question: why is it so difficult to find good low-sodium junk food like chips and pretzels?)

A comment on Joanna’s Food blog about salt and rising time gives me some ideas to work from:

Broadly speaking, the shorter the rising time the more yeast and less salt are needed, but this is an over-simplification because proportions of both are determined by the volume of dough concerned. The larger the batch, the relatively smaller the proportion of yeast, so the balance of salt must be adjusted, at any rate in theory, to the time calculated for the fermenting or rising of the dough.

I say in theory because when it comes down to a small batch of home-baked bread, it really is not necessary to make elaborate calculations. A few experiments will surely show what is the proper quantity of all the ingredients, their relation to rising times, and to the ultimate flavour and texture of the bread. When it comes to finding out what went wrong with a loaf or a batch of bread, made apparently in every respect identically with your last successful one, then is the moment to try to remember whether perhaps your salt was carelessly measured, or if you guessed at the quantity instead of weighing it as usual.

…To me, bread with a very low salt content is virtually uneatable, and in my calculations for the rising time of the dough the extra salt I put in is allowed for. It is worth remembering that a proper proportion of salt helps the retention of moisture in the baked loaf, and that too much makes for a hard crust.

For an overnight or eight-hour rising the yeast can again be decreased without reducing the salt content It would be the high proportion of salt which would slow up the action of the yeast, and prevent the dough over-fermenting or developing a sour taste The very short rising and proving times, often as little as 40 minutes all told, sometimes given on flour-packet recipes, can only be explained by the minimal salt content of the dough.

I generally use kosher salt, because that’s what we have in the cupboard (it’s used to rim margarita glasses in summer). We also have some sea salt and a chunk of solid Himalayan rock salt that needs to be broken into small pieces and crushed before it can be used (that will be a challenge because rock salt is, well, rock, and damned hard; a hammer may become a new kitchen implement for this use).

There are many other types of salt, not all suitable for baking, and some with more or less flavour (“designer” salts have arrived, many from exotic locations, all costing considerably more than table salt). None of these variants provide any real difference in nutrition, except for the iodine in some processed salts. The trace minerals in sea salts are in such small quantities they offer a negligible effect.

We don’t own any commercial table salt, but I wouldn’t use it in bread because of the chemical stew of additives: “up to 2% of suitable food-grade anti-caking, free-flowing, or conditioning agents” – like calcium silicate, sodium aluminosilicate, calcium aluminosilicate – and sugars:

Dextrose, when added (typically at about 0.04%), acts as a stabilizer for potassium iodide in salt, preventing it from disassociating into “free” iodine, which may be lost from the salt through simple vaporization. When combined with good packaging, these additives ensure that iodized salt retains its ability to combat iodine deficiency disorders, even while remaining in the kitchen pantry for long periods of time.

Anti-caking agents are also added to salt used for de-icing. Although de-icing salt is typically a very coarse particle size, it usually contains a small proportion of fine crystals, which cause clumping. This phenomenon is exacerbated by the salt’s continual exposure to humidity and precipitation. The most frequently used additive is sodium ferrocyanide, also known as Yellow Prussiate of Soda (YPS). Another is ferric ferrocyanide, also known as Prussian Blue. They are added in amounts of 20 to 100 ppm.

YPS is approved by the Food and Drug Administration as an anti-caking additive in table salt based on exhaustive tests demonstrating no evidence of toxicity at levels considerably higher than those used in highway deicing salts. Prussian Blue is also used in household bluing, blueprints, blue-black ink and carpenter’s chalk and is also non-toxic to animal and plant life.

I’m not sure what effect any of these would have on yeast or gluten, but I’d rather not experiment. However, other cooks have commented on salt use without finding any real difference between types.

Vegan Health warns:

Today you will find that iodized table salt is composed of insoluble inorganic elements like:

• Potassium chloride
• Potassium sulphate
• Magnesium bromide
• Calcium chloride
• Sodium sulphate
• Barium chloride
• Strontium chloride

These elements may be good for household cleaning, but not for human consumption.

Although the page lists several of the more expensive “designer” salts as table salt alternatives, I think I’ll avoid the extra costs and continue to use what’s in the cupboard. Given the amount I use in a typical week, I have enough to last a few more years at least.

And, as the Foodlab tells us:

…chemically there is virtually no difference between table salt, kosher salt, and fancy sea salt. All of them are close to 100 percent pure NaCl (sodium chloride), with a few trace elements thrown in.

The biggest difference in salts is in density. Table salt, comprised of smaller grains, is 1.5-2.5 times more dense than other types of salt that have large flakes or crystals. A teaspoon of table salt has a lot more salt in it than a teaspoon of large flake salt like kosher or some sea salts: taste-wise, it is a lot saltier in effect than less dense varieties, measured by the tablespoonful. Table salt is about 280g per cup – roughly the same weight per cup as water – whole kosher salt ranges from 140-225g per cup.

Since I measure my ingredients by weight, not volume, however, the difference is moot. 10g of salt is 10g of salt regardless of type. And given the small amount used in baking, any imparted flavour difference is likely too small to notice.

No conclusions come forward: just more notes for experimentation. Salt is necessary, but how much? I have yet to ascertain if  there is an optimum for dough quality, as well as a minimum and maximum amount. Taste is, of course, subjective, and I would err on the side of the least salty result, as far as my tastebuds are concerned.

Tonight’s exercise in breadmaking will be an opportunity for me to try some ideas and see what I can do with and without salt.*

~~~~~~
* Maybe…I have it in mind to try either a coconut bread or a pumpkin-cranberry bread. Or even a mix of the two…