Technical Talk: A Study of Salt

Question: Why is salt important for the formulation of baked goods and how can the industry reduce or replace it?

This column is written by Dr. John Michaelides of the Guelph Food Technology Centre, 519-821-1246, www.gftc.ca .

Question: Why is salt important for the formulation of baked goods and how can the industry reduce or replace it?

Answer: Salt is a widely used food ingredient around the world. Humans have used salt in or on their foods for thousands of years. We are all familiar with its role in food preservation and the enhancement of taste, however, salt has additional functional roles in many food formulations. Salt’s functionality and importance in baked goods will be the focus of this article.

It is widely recognized and accepted that common salt has a detrimental effect on human health by increasing the risk of cardiovascular disease. This is mainly attributed to the major component of salt, sodium. Sodium accounts for 39 per cent of common salt’s make-up. Sodium is the component of salt that plays the critical role of increasing blood pressure, so consuming high levels of salt can contribute to conditions like hypertension. Salt’s effect on other chronic diseases is still under debate. Sodium also plays a very important role in the function of the human body and the absence of sodium from our diet would be detrimental to overall health. Many would like to reduce their salt intake, but the complete elimination of salt from our diets is not possible. Human dependence on salt goes beyond basic body function; there are other factors that would make elimination of salt impossible. One reason is cultural: humans are accustomed to the flavour enhancement that salt provides. Without salt many of the foods we eat would not be as palatable. Other reasons are functional; for instance, salt plays a key role in preserving food. It also has a more complex functional role that affects large-scale production of food products. While salt is critical in our food system, there is still an opportunity to reduce the amount used to a healthier level. As part of their health initiatives many large food companies are targeting salt reduction. The major emphasis of these initiatives is on research and formulation changes.

Common salt (sodium chloride) plays an important role in the formulation of baked goods. It is considered as one of the major ingredients in bread baking, along with flour, water and yeast. Salt does not present as just an isolated flavour, it also acts to enhance other flavours within the formulation. In fact, at the levels normally used in the formulation of baked goods salt does not impart a salty taste. It is well known that baking without salt results in bread with bland and non-descript taste. Salt not only enhances other flavours but increases sweetness, masks metallic and bitter flavours as well as many other undesirable tastes in food. This sweetness enhancing and masking functionality is used often in sweet baked goods.

Salt also contributes in controlling and stabilizing yeast fermentation in dough systems. Salt will prevent over-fermentation. Over-fermentation creates dough with excessive gas and sourness, and gives finished baked goods undesirable open grain and poor texture. Salt acts to lower the gas production rate and therefore produces the longer proof times needed for good-quality baked goods.  Salt changes the osmotic pressure within the yeast cell thus controlling the yeast activity. The science behind the effect of salt on yeast cells is beyond the scope of this article and will not be discussed in detail. Salt is, however, an effective tool in controlling the action of the yeast and gas formation. This is especially true where temperatures cannot be easily controlled, like the conditions found in small bakery establishments.

Salt also affects proteins in various food systems. The wheat gluten protein, which is the fundamental component of the baking process especially for the yeast-raised products, is also affected by the presence of salt. The hydration of gluten, as well as its development and strength, is dramatically affected by the salt content in the formula. The hydration of flour is achieved at a slower rate with the addition of low levels of salt in the formulation. The slower rate is achieved because salt shields the gluten’s overall positive charges, therefore reducing repulsion and allowing the proteins to come in closer contact. This will result in a slower hydration rate of the flour and therefore an increase in the mixing time required to develop the dough. This is important because longer mixing time will result in a slower rate of production in large bakeries and thus increase energy consumption and slower production outputs. This problem can be corrected by the addition of the salt at a later stage of the process when the dough forms and no longer sticks to the side of the mixer. In addition, salt may also reverse the loss of elasticity in doughs that have been over-mixed and have lost their elastic properties. Common salt is known to increase dough strength at its normal level of addition (1.5 to 2 per cent) in bread formulations. However, the addition of salt above these levels does not improve the loaf volume of bread. Unfortunately, when a sodium chloride substitute is used, there could be a detrimental effect on the loaf volume and other characteristics of the bread.

Salt has a critical effect on both hydrophobic (water repelling) interactions and hydrogen bonding properties of the gluten proteins thus affecting the rheology and the overall development of the dough. Different salts (other than sodium chloride) have different effects on the proteins and some may be suitable as replacements for traditional salt. These could be viable alternatives in our efforts to reduce sodium in baked goods. The effect these alternatives will have on the dough and the yeast is dependent on the type of ions they carry and this can present a challenge when substituting.

Many efforts have been made both from ingredient manufacturers and food companies to reduce or completely replace salt in food products. Some success has been generated using potassium chloride as a substitute. Manufacturers have reported success with as much as a 50 per cent potassium chloride, 50 per cent sodium chloride mix. Although potassium chloride has similar effects on the baking process to sodium chloride the major problem with this salt is the introduction of a metallic taste, which cannot be easily masked in various foods. Other salts that can possibly, at least partially, replace sodium chloride include magnesium chloride, magnesium acetate and potassium gluconate.  Other low-sodium salt replacers are also on the market. These may include blends of sodium chloride with potassium chloride, magnesium sulphate and the amino acid L-lysine hydrochloride. Ingredient suppliers are actively involved in developing replacers and some are now available. These include Lo Salt, Saxa So-low, Morton Lite Salt and others. Recently, Jungbunzlauer introduced Sub4salt Salt, an ingredient that is claimed to replace salt by 35 per cent in bread and other baked goods without affecting the taste and processing properties. In addition to salt replacers, flavour enhancers may be used, which work by activating receptors in the mouth and compensate for the salt taste reduction. Such enhancers include yeast extracts, nucleotides and a recently introduced Danisco ingredient SALboost. Monosodium glutamate is also used as a flavour enhancer, but it is not as desirable, as it contains sodium and its use is somewhat controversial.

Before venturing into replacements using other salts or commercially available replacers and enhancers, make sure of the regulatory status of these ingredients both for domestic use and the export market.

Remember, direct replacement may not be practical and there will be additional effort needed in the reformulation process in order to achieve the desired results.

For more information, or fee for service help with product or process development needs please contact the GFTC at 519-821-1246, by fax at 519-836-1281, or by e-mail at gftc@gftc.ca .