*4.3. The Use of Flavor Enhancers as Substitutes for Sodium Chloride in Bakery Products*

Flavor enhancers are compounds that do not have a salty taste, but they have the ability to intensify the salty taste of NaCl by activating receptors in the oral cavity. Some of them also mask the unpleasant taste of KCl. Yeast extracts are natural flavor enhancers, which the food industry commonly uses as substitutes for monosodium glutamate (MSG) and other artificial flavor enhancers. However, the effectiveness of MSG (as a salt substitute) is only partial, as it also contains sodium. Moreover, another problem is that the safety of MSG use is controversial because it has been associated with health problems (such as headaches, hyperactivity, and metabolic disorders) [13]. Glutamic acid-based combinations for salt replacement by flavor enhancement and intensification lead to good results [116]. As for yeast extract, although it is considered a natural and healthy alternative, it often contains MSG, which has been used in the food industry since the 1950s and has changed significantly in terms of quality, taste and functionality. Several low-sodium natural yeast extracts have been developed and can be used in a variety of salty foods. Yeast extracts are obtained from the water-soluble content of the cells, which contains concentrated amino acids, peptides, carbohydrates and mineral salts. In general, two types of extracts can be produced to the industrial level, using two different methods namely autolysis and hydrolyses. Autolysis of yeast extract is produced by processing yeast used in the bakery or beer industry. Cell walls are broken down by the use of heat or salt. This allows the enzymes present in the cell to break down the proteins and other cells compounds. The soluble compounds are then separated from the insoluble compounds and concentrated and pasteurized before being used in the food products [117]. The production of hydrolyzed yeast extracts implies the use of an acid, which starts the peptide bonds hydrolysis, releasing glutamic acid. Yeast extracts can be added to any salty food and are commonly used in sauces, spices and culinary products. Strong fleshy notes are also used to mask any unpleasant bitter taste resulting from the incorporation of potassium chloride into foods. This is a positive fact because the sensation of bitter taste induced by potassium chloride limits the amount in which it could be incorporated into food. This allows an increase in the amount of potassium chloride that could be added to foods containing yeast extracts in the bread making recipe [118]. It should also be mentioned that these ingredients do not have the same profile, in terms of NaCl functionality, on dough rheology, yeast fermentation rate, control of water activity and inhibition of microbial growth, which can create difficulties

in bakery industry. Therefore, even it presents a high potential for flavor improvement, yeast extracts are not well received by the consumers, which limits the acceptability of the food products where they are incorporated. To balance the overall flavor and overall characteristics of bread quality, the combination of salt substitutes with flavor enhancers is recommended to be used [12].

#### **5. Perspectives**

The strategies of bakery products reformulation in order to reduce salt are nowadays of a great interest to an international level, supported by the authorities and research community to benefit consumer health. It represents a great challenge for the bakery industry, since sodium chloride is one of the raw materials for bakery products with important effects on their technological and sensory properties. Due to the important role of NaCl it is difficult to reduce or to eliminate it completely from bakery products. However, baking industry undertakes efforts to reduce the salt content from baked products.

In the salt reduction strategies will be taken into account the economic and technical criteria, but also the acceptability of the bakery products with a low salt content by consumers.

Gradual reduction of salt from bakery products may be one of the best solutions for the industry and consumers in the future without significant costs. Moreover, the use of different salts with similar effects from the technological point of view (KCl, MgCl2, CaCl2, calcium lactate, calcium gluconate, etc.) to those of NaCl addition may play an important role of salt reduction in baked products but their uses are limited due to unpleasant taste. Some taste enhancers (amino acids, yeast extracts, glutamates, hydrolyzed vegetable proteins nucleotides, fermented sugars, etc.), B4 vitamin may be used in the future to the industrial level in combination with other salts to improve the salty taste of baked products.

To obtain bakery products with a low salt content the NaCl may be totally replaced with sea salt (a natural mix of NaCl, KCl, MgCl2) with a low sodium content but it use may be limited due to it higher cost which may be problem in poor and developing countries in which bakery products are also low cost ones.

In order to produce bakery products with low salt amount, with technological and sensory characteristics comparable to bakery assortments obtained with a normal salt content, in the future it is recommended to continue researches to combine different ingredients with similar technological effects as those of NaCl which can improve each other their salty taste, to optimize production recipes and to implement different industrial processes such as encapsulation, inhomogeneous distribution of salt in the bakery process, etc.

Therefore, further researches are needed to obtain bakery products assortments with a low salt amounts, with good technological characteristics, by complying with WHO recommendation and consumers demand.

#### **6. Conclusions**

Salt is a minor component, which influences all phases from the bread making technological process, as well as the sensory properties of the bakery products obtained. From the technological point of view, salt presents a significant effect on dough mixing, fermentation and baking. Its affects dough development time, it presents a strengthening effect on the gluten network, makes it more extensible, it inhibits yeast activity leading to a decrease of the gas formed during the fermentation process, it extends the shelf life of the bakery products and it improves the bread sensory characteristics, especially taste, flavor, and the color of the crust. Due to the fact that World Health Organization recommends a daily sodium intake of 2 g equivalent to 5 g/day of salt intake food processors are concerned to reduce the salt content from their products. Bread is the most consumed food worldwide and that way it is the mainly contributor to the sodium daily intake.

The research made so far presents different strategies to reduce sodium from bakery products content (gradual reduction of salt levels from foods, uses of different types of mineral salts, of flavor enhancers, different ingredients with flavor compounds, etc.). Any of these strategies of salt reduction are efficient in some ways. The easiest solution in salt reduction is it gradual reduction over time up to 25% from bakery products recipe. This does not imply any additional costs and technological changes. If this reduction is made under a longer period of time it does not affect the consumers acceptability. Salt replacers (KCl, MgCl2, CaCl2, calcium and magnesium salts as gluconate and lactate) may substitute in a limited way NaCl from bakery products recipe due to their unpleasant flavor. However, they have technological advantages since their effect are similar to that obtained by NaCl addition in bakery products. KCl presents the most similar technological effects in baked products being the most common used salt for NaCl substitution. Up to 20–30% of NaCl substitution, KCl may lead to good bakery products quality without any negative effects on its metallic and bitter taste. The use of sea salt with low sodium content it is in an increasing trend nowadays for it use in bakery products due to the fact that may conduct to good bakery products quality with similar characteristics with those obtained through NaCl addition. Some taste enhancers (glutamates, yeast extracts, hydrolyzed vegetable proteins nucleotides, amino acids, fermented sugars, etc.) can also be used to intensify the salty taste perception in combination with different salts. These present an insignificant effect from the technological point of view and that way their combinations with other types of salts are necessary. The use of dry sourdough in bread recipe may also improve bakery products flavor and may be used in combination with different type of salts or taste enhancers to reduce the sodium content from bakery products.

The results indicate that different strategies may be used in obtaining bakery products with low sodium content of a good quality from a technological and sensory point of view, with benefic effects on consumer health and in agreement with WHO sodium recommendations values.

**Author Contributions:** A.V., A.D. and G.G.C. contributed equally to the study design, collection of data, development of the sampling, analyses, interpretation of results and preparation of the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

