Salt Substitute

Salt Substitutes

The use of “lite,” “low-sodium” and “salt-free” salt substitutes is discussed in Chapters 7 and 9Chapter 7Chapter 9. In general, do not use salt substitutes where sodium is a vital ingredient in the success of a dish or baked item. A higher ratio of sodium chloride to potassium chloride moderates some of the bitterness, but then it is not a sodium-free product.

28 Should patients with heart failure be told to use salt substitutes instead of salt?

In some cases, the answer is no. Many salt substitutes contain potassium chloride in place of sodium chloride. This could lead to potential hyperkalemia in patients on potassium-sparing diuretics, ACE inhibitors or ARBs, aldosterone antagonists, and in those with chronic kidney disease (or those with the potential to develop acute renal failure). Patients who are permitted to use salt substitutes need to be cautioned about potassium issues.

Highlights

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Currently, there is no completely efficient substitute for sodium salt.

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The use of herbs, spices or blends confers new tastes and/or tactile sensations that may mask the absence of sodium.

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New ingredients, such as grape pomace derivatives, have emerged as an interesting approach.

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More sensory studies are needed in seeking for efficient salt substitutes.

4.1 Substitutes

The most common substitutes for sugars (sucrose) are either high-intensity sweeteners (e.g., sucralose and aspartame) or low-intensity sweeteners (e.g., sorbitol and xylitol), but there are issues involving their use, including bitter side tastes and different temporal sweet profiles. Moreover, sugar impacts the texture perception of foods, typically providing a thicker mouthfeel (Hutchings et al., 2019), which is usually not mimicked by sucrose substitutes.

Sodium chloride (NaCl) is the most widely used compound to impart a salty taste to foods. Salts may be included directly in food formulations or they may be applied as solid crystals sprayed on food surfaces (especially on crunchy snacks). Salt crystals are often dissolved rapidly when they come into contact with saliva, which leads to a saltiness perception after foods are introduced into the mouth (Sun et al., 2021). Salt also plays important roles in determining food structure (e.g., water holding capacity and texture) and stability (since it reduces water activity, which contributes to microbial growth inhibition). However, high sodium intakes have been linked to an increased occurrence of high blood pressure, which has motivated the use of salt replacers and the development of methods to reduce the amount of NaCl added to food products (Inguglia et al., 2017). Reduction of the sodium content is often carried out by replacing NaCl with other salts, mainly potassium chloride (KCl), but this can impart bitterness to food, especially meat products (Rios-Mera et al., 2019; Stanley et al., 2017).

The limitations of sugar and salt substitutes has led researchers to investigative alternative approaches of reducing the sugar and salt levels in foods, without adverse affecting their desirable physicochemical and sensory attributes.

2.2 Salt alternatives, salt mixtures and flavour enhancers

A good strategy to improve the palatability of reduced salt foods relies on the use of salt replacing ingredients. There are many different types of substitutes currently being used by the food industry, where their action is to replicate the role of salt without affecting the saltiness of the products. Restructured items such as sausages or deli-style meats are products in which lower-sodium ingredient options have been successfully produced. In these products, the structural functions of salt-soluble proteins have been replaced by the addition of soy or milk proteins, gums and starches (Desmond, 2006; Fellendorf et al., 2016). Common types of salt substitutes are made of mineral salt; the most commonly used is potassium chloride (KCl). The preservative effect of KCl was tested with a preliminary study on laboratory media using a different range of pathogenic bacterial species such as Aeromonas hydrophila, Enterobacter sakazakii, Shigella flexneri, Yersinia enterocolitica and three strains of Staphylococcus aureus. Results from this study confirmed that, compared to NaCl, KCl has an equivalent antimicrobial effect on these organisms when calculated on a molar basis (Bidlas & Lambert, 2008). However, even partial substitution of NaCl with KCl generally has negative consequences on flavour and texture of the product. Gou, Guerrero, Gelabert, and Arnau (1996), evaluate the effect caused by substituting NaCl with KCl (0–60%), potassium lactate (0–100%) and glycine (0–100%) on the texture, flavour and colour characteristics of fermented sausages and dry-cured pork loins. Important flavour defects were detected with substitutions above 40% in both products substituted with KCl and K-lactate and with substitutions above 30% when glycine was used in dry-cured loin. Moreover, in fermented sausages, loss of cohesiveness was detected by the sensory analysis at substitution levels higher than 30% with K-lactate and higher than 50% when glycine was used. Similar studies have shown that partial substitution of NaCl (above 40%) with mixtures of KCl/glycine or K-lactate/glycine, caused flavour and texture defects when used in fermented sausage (Gelabert, Gou, Guerrero, & Arnau, 2003). Potassium, sodium, and calcium lactates seem to be equally effective in controlling the growth of bacteria in packaged meat products. In particular, a combination of potassium lactate and sodium diacetate in packaged cooked meats maintained sensory quality and shelf-life, while reducing NaCl levels by 40% (Devlieghere, Vermeiren, Bontenbal, Lamers, & Debevere, 2009). Sodium lactate is extensively used for Listeria control and shelf-life extension in processed meat products and is the second biggest contributor to sodium content after curing salt. In this instance, potassium lactate is a suitable alternative for low sodium applications because it has similar structural functions and bacteriostatic control (Gou et al., 1996). Potassium lactate exhibits antimicrobial properties against C. botulinum, Staphylococcus aureus and L. monocytogenes and, in addition, it has a positive effect on water holding capacity which may result in a higher cook yield and an improved texture for the cooked product (Stekelenburg, 2003).

The use of replacement ingredients and their impact on product taste depends, not only on the type of replacer used, but also on the meat product-type and on its formulation (Fellendorf et al., 2016).

Studies on black pudding samples, formulated with different fat (10%, 5%) and sodium (0.6%, 0.4%) content, were used to test different salt replacer formulations: samples with 5% fat and 0.6% sodium were supplemented with KCl glycine mixture (KClG) and seaweed, while the sample with 10% fat and 0.4% sodium were supplemented with carrageen. Results indicate that the addition of salt replacers showed an increased spiciness, saltiness or fatness perceptions, not observed consistently in the other two salt and fat formulations used in the study. Within the category of flavour enhancers, amino acids like arginine and related compounds can be used to intensify the perceived saltiness in low sodium products. Similarly, the addition of citric/lactic acids may enhance the perceived saltiness of NaCl (Dotsch et al., 2009; Liem et al., 2011).

Within the set of salt reduction solutions, the development of salt mixtures with low sodium content is one of the possibilities. An example is the commercially available Pansalt^®, a mixture of potassium chloride, magnesium sulphate, and l-lysine hydrochloride. A study by Ketenoglu and Candogan (2011) reported no negative effects in comparison to NaCl-containing patties, on technological and sensory properties of ground beef patties formulated with the Pansalt^® mixture. Another low salt mixture commercially available is Sub4salt^®, made of NaCl, KCl and sodium gluconate, it claims to allow up to 30% sodium reduction without a significant taste difference in hams and emulsified sausages (Jungbunzlauer, 2013). A recently developed product from the same manufacturer is sub4salt^® cure. This product combines the use of sub4salt^® with NaCl (0.5%/0.9%) and claims to allow the production of cured meat products that have up to 35% reduced sodium content. Trials with a standard curing salt (control) and sub4salt^® cure showed no differences in sensory or physical properties, like taste, texture and colour. Moreover, safety parameters such as microbial count, pH-value, and water activity values for both products showed the same optimal range compared to the control (Jungbunzlauer, 2012). Mixtures of 70/30% NaCl/KCl or 70/30% NaCl/MgCl₂ have already been successfully employed for salting ham by Collins (1997), with no reported organoleptic or quality differences when compared to hams made with 100% salt.

Salt enhancers are another category of ingredients used to improve salt flavour. The most frequently used are ingredients such as: yeast extracts, hydrolysates vegetable protein (HVP), monosodium glutamate (MSG) and 5′ nucleotides (Brandsma, 2006; Jimenez Albo-Joglar, 1999). MSG, for example, can be added to sausage products to mask the replacement of NaCl with KCl. A study presented by Santos et al. (2014) where fermented cooked sausages were produced by replacing 50% and 75% NaCl with KCl, showed that the addition of MSG, disodium inosinate, disodium guanylate, lysine and taurine, masked the unpalatable taste caused by the reduced sodium content. Other products such as yeast autolysates, i.e. Provesta^® and Aromild^®, can assists in masking the metallic flavour of KCl and reduce NaCl by up to 20% (Desmond, 2006). A problem with autolysates is their strong broth flavour, which may be not desirable in some products. However, these preparations can be optimized for meat products where they carry a neutral flavour and optimal umami effect (Lilic & Matekalo-Sverak, 2011).

The main limitation for the use of the most common salt substitutes is the metallic flavour caused by KCl; In addition, concerns arise about the risks associated with a higher load of potassium, especially for those affected by conditions including: type I diabetes, renal disease and adrenal insufficiency (Khaw & Barrett-Connor, 1984). In the case of salt enhancers, yeasts and HVP can themselves contain a salt level of up to 40% and therefore, the amount used must be limited. Moreover ingredients such MSG are linked to possible health implications like hyperactivity, sickness and migraines (Fernstrom, 2007), as well as being classified as food additives, which in general are not perceived well by consumers (Soon-Mi et al., 2011). In terms of bacterial safety, the effectiveness of alternative salts compared to NaCl seems to vary based on the product and on the pathogen of interest (Taormina, 2011). More applied information on real food products are necessary to confirm that NaCl can be safely replaced by other compounds. Moreover, if the substituted NaCl level is substitute or decreased to too low concentration, it may be necessary to consider increasing the concentrations of other preservatives or enhancing the safety measures taken during food processing (i.e. cooking, packaging) and during storage in order to attain similar safety levels or meet required product shelf-life.

5 Application

At present, in order to promote reduction of sodium salt, the food industry normally uses sodium salt substitutes (e.g. potassium chloride, calcium chloride, etc) to replace NaCl, but this method tends to elicit adverse flavor effects such as bitter or metallic taste. At the same salt taste intensity, the consumption of sodium is significantly reduced. Compared with sodium salt substitutes, salt taste-enhancing peptides have obvious advantages, but the main challenge is that it is difficult to find suitable types for application in the food industry.

Salty peptides are peptides that can elicit saltiness and can be directly used as salt substitutes in the food industry. As salt taste receptors respond only to sodium and some certain mineral ions, there are a few salty peptides that can directly replace salt. In the practical applications, Zhu et al. (2008) used Aspergillus oryzae to ferment soybean, and found three dipeptides with salty taste, namely Ala-Phe, Phe-Ile and Ile-Phe. Similarly, Amorim et al. (2018) also applied peptides as salt substitutes in the study of coated cashew nut.

Generally, salt taste-enhancing peptides are derived from a variety of protein sources, since Arg-containing dipeptide, MRPs and γ-glutamyl peptides have been reported to exhibit a pronounced salt taste-enhancing effect. Arg-Pro, Arg-Ala, Ala-Arg, Arg-Gly, Arg-Ser, Arg-Val, Val-Arg and Arg-Met showed a good salt taste-enhancing effect (Alexander et al., 2011; Hong et al., 2016). The MRPs obtained by Maillard reaction of soybean (Zhang et al., 2018), sunflower (Chen et al., 2019) and turkey meat (Hong et al., 2016) peptides can also be used as salt taste-enhancing peptides. In addition, the research on kokumi-imparting peptides, e.g., γ-glutamyl peptides has paved a new way for the preparation of salt taste-enhancing peptides. At present, a variety of protein raw materials has been found to serve as the precursors of saltiness-enhancing peptides, including chicken (Liu, Song, et al., 2015), Larimichthys polyactis (Wu et al., 2017), and soybean (Yu et al., 2018) proteins. The salt taste-enhancing peptide prepared by An et al. (2017) using Harpadon nehereus protein has also been used in the production of cookies to reduce the usage of salts.

Application of metallic-based salt substitutes in dry-cured meat products

Dry-cured meat products are traditional products whose production is based on salting, drying and ripening stages, usually whole pieces, which result in a product with particular characteristics of colour, flavour and texture. Dry-cured ham, lacón, cecina, loin, bacon, jerked beef and pastirma are between the main representatives of these type of products.

Different studies showed that substitutions greater than 25% would lead to the appearance of defects in texture, aroma and flavour, colour and in general a lower acceptability of the products by the consumer [13]. Regarding physicochemical properties, colour is one of the parameters that most influence consumer when purchasing a product. The results found in the literature are different depending on the type of product. In this regard, the use of salt mixtures (KCl, CaCl₂ and MgCl₂) did not show a significant effect on colour parameters in dry-cured lacón [14], while in cecina CaCl₂ and MgCl₂ led to increases in lightness and reductions in redness [7^•]. NaCl also influences water holding capacity, since contributes to the reduction of water activity and to the development of chemical and biochemical reactions responsible for the texture of the final product. Thereby, texture parameters are influenced by partial replacements. In this sense, lower NaCl contents observed in samples elaborated with salt mixtures could be responsible for the higher shear force values due to the negative correlation between moisture content and shear force [14], while replacements of 70% NaCl by metallic-based salts caused significant effects on texture parameters, leading to softer textures.

On the contrary, the use of other chloride salts could modify the activity of some endogenous enzymes, which would intensify proteolysis reactions. As a result, higher amounts of free amino acids (FAA) were noted in dry-cured meat products [25,26], being leucine, valine, alanine and phenylalanine the most abundant. These specific FAA might have an impact on sensorial properties, since their concentration is related to bitter flavours [27]. In addition, the use of dichloride salts (CaCl₂ and MgCl₂) promoted cathepsin activity, leading to higher proteolysis index, while ZnCl₂ slightly inhibited it in dry-cured pork butts [28]. The changes that occur in the structure of myofibrillar proteins could be responsible for the possible relationship between proteolysis and protein oxidation reactions in low-sodium meat products [29]. Replacement of NaCl by KCl led to an increase in protein oxidation, which is reflected in a higher carbonyl content while thiol content is reduced [26,30].

All the aforementioned effects could cause modifications in the sensory attributes of the product, which could affect the acceptance of the product by the consumer. Contradictory results were found in the bibliography, but in general, the higher the percentage of salt substituted, the greater the effects found, especially when the substitute is KCl [17^••]. In general, salt replacers did not compromise the main sensorial attributes.

4 Reducing sugar and sodium contents

Despite public health concerns on the risks of high sugar and sodium diets, reducing their contents in food is still a challenge, since consumers demand food products with high sensory appeal, and both sugar and salt play an important role in determining the sensory profiles of sweet and savory foods, respectively. The conventional approach to reduce both sugar and sodium contents in foods is by using substitutes.

1 Introduction

In human history, sodium chloride (NaCl), also called common salt is traditionally one of the most widely used condiments in daily life. NaCl is a neutral inorganic compound with salt taste, which plays an important role in maintaining the balance of osmotic pressure in the human body. The purpose of salt used during food processing mainly includes sensory, technological and preservative functions. Meanwhile, as an essential food processing ingredient, salt can improve the flavor of pickled vegetables, bacon as well as ham, and extend the shelf life of various foods (Hurst, Ayed, Derbenev, Hewson, & Fisk, 2021). In addition to improving food flavor, salt also has a certain preservative effect by reducing the rate of microbial growth, mostly through binding to water molecules, which reduces water activity of food. Normally, in order to improve taste during processing and preservation, more salt is added to food products, leading to excessive sodium consumption that exceeds the recommended daily intake level, which can exert a negative impact on human health. Excessive intake of NaCl is reported to affect human health, leading to cardiovascular diseases, hypertension, and end-organ damage (James & James, 2018; Robinson, Edwards, & Farquhar, 2019; Shen et al., 2022). At present, the global average salt intake per capita has reached around 9–12 g/day, which is far more than 6 g/day recommended by the World Health Organization (WHO). Furthermore, WHO stated salt reduction strategy of 30% by 2025. (Raquel et al., 2020).

Nowadays, two major salt reduction strategies are commonly used in the food industry. The first one is direct salt reduction, including reducing salt consumption and changing the structure of salt (Hurst et al., 2021). However, reducing salt consumption can largely affect the taste of food, including reduced taste and defects in taste (Ulla et al., 2017). In addition, salt acts as a preservative by altering the availability of water in foods, impacts the texture of foods by altering the structure of proteins, and provides nutrient elements needed by the body. The changed structure of salts, such as preparing hollow salt particles and redesigning the size of salt particles, requires advanced processing technology (Hurst et al., 2021). There has been limited success in the direct salt reduction in UK and EU countries. For instance, the partial replacement of 30% NaCl with KCl did not significantly affect the sensory characteristics of toast bread. However, excessive usage of NaCl substitutes (≥40%) can elicit bitter and metallic taste, which constitutes flavor defects in foods and might impact consumer acceptance (Antúnez, Giménez, Vidal, & Ares, 2018). Another method is to employ salt substitutes (Barnett, Diako, & Ross, 2019; Pateiro, Munekata, Cittadini, Domínguez, & Lorenzo, 2021). The food industry currently employs certain mineral salts, such as potassium chloride and calcium chloride to replace NaCl in food formulations (Mirian, Paulo, Aurora, Rubén, & José, 2021; Raquel et al., 2020). In addition, some studies have reported that excessive intake of potassium (over 4.7 g/day) can lead to acute toxicity, provoking hyperkalemia and arrhythmias (Raquel et al., 2020). Additionally, another effective way to reduce usage of salt is to use taste enhancers. Currently, the commonly used taste enhancers include monosodium glutamate (MSG), nucleotide phosphates (IMP/GMP), herbs and spice mixtures, certain basic amino acids and salty peptides. The salt taste enhancer itself has no salt taste, but when it is mixed with sodium chloride, which can enhance the perception of salt taste. However, MSG and IMP/GMP still contain sodium ions, while excessive intake is still detrimental to cardiovascular health. A recent review has discussed the impact of basic amino acids on the muscle protein processing properties (physicochemical, gel, and emulsion characteristics) and quality (proteolysis, lipolysis, protein oxidation, lipid oxidation, sensory, and textual properties (Zhang, Guo, Peng, & Jamali, 2022). The research and application of salty peptides/salt taste-enhancing peptides will be a potential strategy for salt reduction.

In recent years, several studies have revealed that some food-derived peptides have a salt taste-enhancing effect, including salty peptides and salt taste-enhancing peptides (e.g., Maillard reacted peptides and γ-glutamyl peptides) (Lu et al., 2021; Yu et al., 2022). For example, some Maillard reacted peptides can enhance the perception of salt taste when mixed with salt, and achieve the same saltiness intensity under the low concentration of salt, thereby reducing NaCl intake (Shen et al., 2022). Furthermore, some peptides have been employed as taste enhancers to reduce salt intake and improve food flavor (Fu, Amin, Li, Bak, & Lametsch, 2021). It has been shown that γ-glutamyl peptides can increase salt, umami and kokumi taste when mixed in food formulation with NaCl (Lu et al., 2021; Xia et al., 2022; Yang, Bai, Zeng, & Cui, 2019). Therefore, the employment of salty peptides and salt taste-enhancing peptides is an important research direction, which has important scientific significance and application value. In this regard, the present review overviews the salt taste receptors and transduction mechanism of salt taste. The recent research progress on salty/salt taste-enhancing peptides from different food proteins have been reviewed. The main evaluation methods of salt taste are also introduced. Additionally, the application prospects and challenges of salty peptides and salt taste-enhancing peptides are also discussed.

Potassium supplements, potassium-sparing diuretics, or salt substitutes

Concurrent administration of potassium supplements, potassium-sparing diuretics, or salt substitutes can precipitate hyperkalemia in ACE inhibitor-treated patients, in whom aldosterone is suppressed [241]. Regular monitoring of serum potassium is essential in these patients, because of the risk of hyperkalemia in patients given potassium (or potassium-sparing diuretics) and ACE inhibitors or angiotensin receptor antagonists.

In a retrospective study, five patients developed extreme hyperkalemia (9.4–11 mmol/l) within 8–18 days of starting combination therapy with co-amilozide and an ACE inhibitor [242].

In eight healthy subjects, treatment with spironolactone and losartan increased mean plasma potassium concentration by 0.8 mmol/l (up to 5.0 mmol/l) and reduced mean urinary potassium excretion from 108 to 87 mmol/l [243].

Until more data are available, it is prudent to consider angiotensin II receptor antagonists similar to ACE inhibitors as risk factors for hyperkalemia in patients taking potassium-sparing diuretics.