4.1.2. The Use of Magnesium Chloride as a Substitute for Sodium Chloride in Bakery Products and the Benefits of Its Use on the Human Body

Magnesium chloride (MgCl2) is one of the most common water-soluble natural magnesium compounds. It is found naturally in the salt waters of lakes or in sea water. Magnesium chloride is obtained from mineral salt deposits after the extraction of potassium chloride but also by direct extraction. Among the main sources of raw materials for the production of magnesium chloride, the most important is sea water. Magnesium can be directly precipitated from sea water in the form of magnesium hydroxide and converted to magnesium chloride [103]. Among the uses of magnesium chloride in the food industries are: coagulant; tofu production from soy milk; formula milk for babies, etc. The advantage of using magnesium chloride in food industry is that it can be a source of magnesium for the human body where it is one of the main minerals present quantitatively after potassium, calcium, phosphorus and sodium participating in carbohydrate, lipid metabolism, growth and cellular permeability. It is a catalytic element and also a plastic one and is a growth factor that helps regulate the balance of calcium in the human body having an anti-aging, anti-anaphylaxis and anti-atherosclerotic role [79]. To replace the nutrient losses in flour that occur during wheat processing and to reduce the risk of a deficiency in the body, the bakery industry has enriched white bread with various nutrients such as iron, thiamine, riboflavin and niacin [104]. Magnesium is considered to be one of the deficient elements in our diet although it is involved in the enzymatic reactions of carbohydrates, proteins, energy metabolism and maintaining the structural and functional integrity of human body tissues [105]. Along the benefits of magnesium consumptions are: fighting constipation, hypomagnesaemia, preventing convulsions in eclampsia/preeclampsia, preventing acute nephritis (pediatric and adolescent patients), cardiac arrhythmias secondary to hypomagnesaemia, etc. [106].

Salovaara [70] found that the addition of magnesium chloride in the dough reduces it development time and increases the water absorption capacity. Compared to the dough samples in which sodium chloride and potassium chloride were added in the bread recipe, it was found that there are significant differences from the rheological point of view only for the samples with magnesium chloride in dough recipe. According to this study, it was recommended the use of KCl as a substitute for NaCl even at high doses of 25–50% because this salt maintains the dough rheological properties, leading at the same time to a significant reduction of sodium in the finished products. This similar behavior between NaCl and KCl on the dough rheological properties is due to the fact that K+ was classified equivalent to Na<sup>+</sup> in the lyotropic series which means that it would have similar abilities to cause protein aggregation and fortify the gluten network. It is considered a stabilizing cation that causes less protein hydration and stronger development of protein structure [99].

4.1.3. The Use of Potassium Chloride as a Substitute for Sodium Chloride in Bakery Products and the Benefits of Its Use on the Human Body

Potassium chloride (KCl) is a natural mineral salt obtained from salts from rocks and seawater, its extraction being similar to that of sodium chloride. Taking into account the dietary intake of potassium, it is clear that it has opposite effects to sodium consumption, namely a low risk of hypertension. While sodium intake is significantly increasing, the average overall potassium intake is below the WHO recommendations of at least 3510 mg of potassium per day.

Potassium is the most abundant cation in intracellular fluids and is an essential nutrient in maintaining cell functions, especially in excitable cells such as muscles and nerves. Being a major intracellular ion, it is manly found in foodstuffs that are obtained from living tissues. A higher amount of potassium was found in fruits and vegetables and less into meat products and cereals. In Western diets, food practices are not based on the fruits and vegetables consumption but rather on cereals and processed foods with a low content of nutrients which led to diets low in potassium and higher in sodium [107]. The best sources of potassium are fruits, vegetables, meat, fish, dairy and nuts. In starchy foods, potassium is found in higher amounts in whole meal flour and brown rice compared to rice and white flour. Milk, coffee, tea and other non-alcoholic beverages are among the main sources of potassium in the American adult's diets. According to the National Institutes of Health (NIH), the US estimates that the body absorbs about 85–90% of dietary potassium and different forms of potassium from fruits and vegetables including potassium phosphate, sulfate, citrate and others, but not potassium chloride (used in salt substitutes and some dietary supplements). Globally, mixtures of salts with potassium chloride are widely used for the partial or total substitution of sodium chloride. The use of potassium chloride can thus reduce the intake of sodium in food in a short period of time and to increase the potassium intake. There is an antagonism between the metabolism of potassium and sodium. Increasing the concentration of potassium in the human body leads to a decrease of the sodium concentration and to an increase in its elimination. At the same time, fluids are eliminated from the body. Diets high in potassium can help us to eliminate sodium from the body. Of all the types of salts used, potassium chloride is one of the most widely used as a substitute for sodium chloride because it has the best ability to transmit the salty perception of taste in food.

Therefore, the potassium chloride may be an interesting substitute for sodium chloride from the perspective of consumers, processors from the food industry but also from the point of view of consumer health. However, potassium chloride cannot be used in unlimited quantities because at high levels it loses its ability to give a salty taste in food and can often lead to a bitter, chemical and metallic taste.

Depending on the category of foodstuff in which it was introduced, potassium chloride has been used in different percentages to replace sodium chloride without affecting in a negative way the sensory characteristics of foods. For example, in aqueous solutions the taste of potassium chloride is perceived at a concentration of 20%, in food products such as pizza type good sensory properties was achieved up to a sodium chloride replacement with potassium chloride of a 25% level, in white and dark bread with 30%, in cheddar cheese with 46% and in feta cheese even up to 50% [66]. Studies have shown that this ingredient can have approximately the same technological functions in the dough making process and bread quality as sodium chloride leading to an improvement in the texture and shelf life of bread [67]. Doyle [52] suggested that the influence of KCl on dough rheological properties is similar to those obtained by using NaCl. Gengjun et al. [71] concluded that KCl could adjust the growth rate of the yeast cells, allowing the incorporation of more gas bubbles in the gluten network, which may have a positive effect on the rheological properties of wheat flour dough.

Consumption of potassium chloride and its use as a substitute for sodium chloride is safe for consumers health and is supported by the presence of potassium in a natural way in different foods. Therefore, the addition of potassium chloride to food has gained regulatory acceptance in the US and the European Union. Experts recommend increasing potassium consumption by its addition in foods for the population because it has a low risk in terms of its adverse effects on consumers.

There is currently no upper limit on potassium intake at the global level, but based on estimates of current consumption in Europe, the European Food Safety Authority (EFSA) states that the risk of adverse effects on potassium intake from food sources per 5000–6000 mg/day is considered low for the clinically healthy population. Moreover, the long-term intake of potassium from supplements at a level of 3000 mg/day in addition to the consumption of foods containing potassium is also considered safe for the clinically healthy adult population [108].

Potassium chloride is one of the most common substitutes for sodium chloride in bread due to its ability to lead to a salty taste perception. It can replace sodium chloride up to a level of 30–40% without changing the characteristics of the finished product [5]. Although KCl is a possible option for reducing sodium in bakery products, a significant disadvantage of it is, as we mentioned before, the metallic taste conferred by this compound at high levels. That's way various studies have assessed the threshold of sensory acceptability. For example, Wyatt and Ronan [109] did not find significant differences between a control sample (with 100% NaCl) and other bread samples with 50%/50% (NaCl/KCl) bread, the highest scores in terms of acceptability having the NaCl ratio/KCl, 75%/25%. In contrast, Salovaara (1982) [70] found significant differences with a mixture of 60/40, but not with a mixture of 80/20. Replacement is not as critical factor for dark bread, and the use of a salt mixture in which the sodium content of the bread obtained is reduced by 32.3% and the K content is increased by 34.8% showed good results in terms of quality and taste of the bread obtained. Finally, in a systematic study involving the replacement of NaCl with K+ salts, Braschi et al. [74] concluded that the best results, other than those for the control sample, were obtained with a 70/30 ratio of K-citrate or a 1:1 mixture of KCl and potassium bicarbonate; they also concluded the complete bioavailability of the incorporated potassium using these salts. Other possibilities that have developed include mixtures of commercial salt and salt from sources of low sodium and high potassium, calcium, or magnesium. The use of KCl in combination with Na glutamate or ribonucleotides may mask the bitter aftertaste. This is another interesting alternative, although this taste tends to be used only in the substitution of salt in meat products [110]. Potassium chloride (KCl) is usually the main choice and can be used to replace from 10% to 20% without major technological and sensory problems. Total KCl replacement is not recommended due to the unpleasant bitter and metallic taste, which limits consumer acceptability. For this reason, for a higher reduction of sodium in bakery products it is recommended to combine it with other food ingredients [12].

Therefore, the advantage of using KCl in the bread making recipe is a technological and healthy one due to the fact that it increases the potassium intake from the diet which is associated with a very low risk of hypertension, an opposite effect to sodium consumption [66]. A recent study estimated that potassium intake for the United States, Mexico, France, and the United Kingdom was 80%, 95%, 77%, and respectively 95%, under the recommendations of the World Health Organization on potassium intake [111].
