Received: 2 March 2017 |  Revised: 25 May 2017 |  Accepted: 31 May 2017
`DOI: 10.1002/fsn3.499
`
`R E V I E W
`
`Monosodium glutamate as a tool to reduce sodium in
`foodstuffs: Technological and safety aspects
`
`Hellen D. B. Maluly  | Adriana P. Arisseto-Bragotto | Felix G. R. Reyes
`
`Department of Food Science, School of Food
`Engineering, University of Campinas, Rua
`Monteiro Lobato, Campinas, São Paulo, Brazil
`
`Correspondence
`Hellen D. B. Maluly, Department of Food
`Science, School of Food Engineering,
`University of Campinas, Rua Monteiro Lobato
`80, CEP 13083-862 Campinas, São Paulo,
`Brazil.
`Email: hdbmaluly@gmail.com
`
`Funding information
`PROEX/CAPES, Grant/Award Number:
`3300301702P1; Institute for Glutamate
`Sciences in South America (IGSSA)
`
`Abstract
`Sodium chloride (NaCl) is the most commonly used ingredient to provide salty taste to
`foods. However, excess sodium in the bloodstream has been associated with the de-
`velopment of several chronic noncommunicable diseases. In order to limit sodium in-
`take to levels considered safe, the World Health Organization (WHO) recommends for
`adults a daily intake of not more than 5 g of NaCl (less than 2 g of sodium). One of the
`strategic actions recommended by the Pan American Health Organization (PAHO) to
`reduce sodium intake is reformulation of processed foods. This recommendation indi-
`cates there is an urgent need to find salt substitutes, and umami compounds have
`been pointed as an alternative strategy. Like salty, umami is also a basic taste and the
`major compound associated to umami is monosodium L- glutamate (MSG). The availa-
`ble scientific data on the toxicity of MSG has been evaluated by scientific committees
`and regulatory agencies. The Joint FAO/WHO Expert Committee on Food Additives
`and the Scientific Committee on Food of the European Commission established an
`acceptable daily intake (ADI) not specified, which indicated that the substance offers
`no health risk when used as a food additive. The United States Food and Drug
`Administration and the Federation of American Societies for Experimental Biology
`classified MSG as a Generally Recognized as Safe (GRAS) substance. In this paper, an
`overview about salty and umami taste physiology, the potential applications of MSG
`use to reduce sodium content in specific industrialized foods and safety aspects of
`MSG as food additive are presented.
`
`K E Y W O R D S
`Monosodium L-glutamate, salty taste, sodium chloride, umami taste
`
`1 |  INTRODUCTION
`
`Over the last few years, significant changes have occurred in the global
`food market, which are mainly due to the growth of the population
`and cities, including Brazil (Trading Economics 2013). These facts may
`be one of the reasons for the increase in the commerce of processed
`foods, such as canned and ready- to- eat products. In 2014, marketing
`studies verified an increase in 9% in this sector, and the expectation
`
`in 2019 is that it could reach a retail volume of 13% of food sales (3.1
`billion units of canned products) (Euromonitor International 2015).
`According to a survey conducted by Brazil Food Trends 2020 (Ibope
`Inteligência 2010), this improvement in the market of processed foods
`may have partly occurred in Brazil due to changes in lifestyle and an
`increased demand from consumers for more convenient products, in
`addition to new launchings and promotional activities. The results also
`pointed out that sensorial quality (indicated by 23% of the consumers
`
`This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium,
`provided the original work is properly cited.
`© 2017 The Authors. Food Science & Nutrition published by Wiley Periodicals, Inc.
`
`Food Sci Nutr. 2017;5:1039–1048.
`
`
`
`  |  1039www.foodscience-nutrition.com
`
`
`
`Ex. 1187
`
`

`

`1040  |    
`
`interviewed), along with health and wellness (indicated by 21% of
`the consumers interviewed), were shown by researchers as future
` consumption trends, which reflect the new demands of consumers.
`In this sense, certain types of products have been more highly valued,
`especially those with reduced sodium, sugar and fat content.
`Sodium chloride (NaCl) is the most used ingredient to provide a
`general flavor in foods. In addition to its role in taste, NaCl and other
`food additives that contain sodium have other functions such as pres-
`ervation, the acceleration of fermentation reactions and texture main-
`tenance (Henney, Taylor, & Boon, 2010). However, excess sodium in
`the bloodstream has been associated with the development of various
`noncommunicable diseases (NCDs), also known as chronic diseases
`that are not passed from person to person, including hypertension and
`other heart problems, kidney disease, stomach cancer, and osteoporo-
`sis. To limit sodium intake at safe levels, the World Health Organization
`(WHO) recommends a maximum daily consumption of 5 g of salt
`(NaCl) for adults, which is equivalent to less than 2 g of sodium/day
`(WHO 2007).
`Based on data published by the Brazilian Household Budget Survey
`(Pesquisa de Orçamentos Familiares – POF) carried out in 2002–2003
`and 2008–2009, Brazilians have been consuming a large amount of
`sodium (4.7 g of sodium/day), which corresponds to more than twice
`the safe level (less than 2 g of sodium/day) proposed by the World
`Health Organization (WHO, 2007). In 2013, a study conduct by Sarno,
`Claro, Levy, Bandoni, and Monteiro (2013) also demonstrated that
`processed foods contributed to at least 25% of the sodium intake
`(mainly the sodium coming from NaCl addition) by middle- class and
`upper- class families of the country.
`The results of these studies were used to strengthen the commit-
`ments between the Brazilian Ministry of Health (Ministério da Saúde
`– MS) and the Brazilian Association of Food Industries (Associação
`Brasileira das Indústrias da Alimentação – ABIA), which were signed in
`2007 and stimulated food producers to improve the supply of health
`foodstuffs, including products with reduced sodium content. To de-
`velop strategies to reduce sodium intake to 2 g/day until 2020, the
`government renewed the agreements (BRAZIL 2007).
`Among these strategies, which should also take into account the
`sensory quality of foods, the use of flavor enhancers such as mono-
`sodium L- glutamate (MSG) can be considered a promising alternative
`with a great potential for application in the food industry (Jinap &
`Hajeb, 2010). MSG, which is the sodium salt of L- glutamic acid (or L-
`glutamate – dissociated form), is the most well- known flavor enhancer
`used in foods, but other molecules such as nucleotides (inosinate and
`guanylate), other glutamate salts associated with ammonium, potas-
`sium and calcium, and other additives that contain elevated concentra-
`tions of L- glutamate, named Natural Flavor Enhancers (NFE), such as
`yeast extract and products from wheat and soy fermentation, are also
`available in the market to enhance the flavor of foods (McGough, Sato,
`Rankin, & Sindelar, 2012; Yamaguchi & Takahashi, 1984).
`According to the Technical Report on Sodium Content in Processed
`Foods published by the Brazilian Health Surveillance Agency (Agência
`Nacional de Vigilância Sanitária – ANVISA) in 2012 and 2013, some
`industrialized products such as soups, stocks and seasonings, instant
`
`noodles, certain snacks, processed meats and parmesan grated cheese
`exhibit very high sodium contents (ANVISA 2012, 2013; Sarno et al.,
`2009). The use of MSG and other flavor enhancers in these foodstuffs
`is allowed in Brazil (ANVISA, 2001) and by the Southern Common
`Market (MERCOSUR 2010). Thus, in this paper a review about salty
`and umami taste physiology, the potential applications of MSG to
`reduce sodium content in specific industrialized foods and safety as-
`pects of MSG as food additive are presented, in order to contribute to
`the development of food products reduced in sodium without impair-
`ing the sensorial quality of the foods and the health of the population.
`
`2 |  TASTE PHYSIOLOGY:
`SALTY × UMAMI TASTES
`
`Physiological mechanisms involved in taste perception have been
`discussed by researchers since the beginning of the 20th century
`(Trivedi, 2012).
`Regarding the salty taste, which is promoted by sodium chloride
`and potassium chloride, among other substances, the hypothesis has
`suggested that ion dissociation occurs when these molecules are in
`contact with saliva. Sodium ions, specifically cross- specific ion chan-
`nels, named ENaCs, which are in the membranes of taste cells. After
`the ions go in, membrane depolarization occurs, charging it positively.
`This depolarization increases the membrane electric potential and
`stimulates taste nerves, sending signals to the brain to recognize the
`salty taste or the presence of ions that activate the electric poten-
`tial (Beauchamp & Stein, 2008; Chandrashekar et al., 2010; Geran &
`Spector, 2000).
`In relation to the umami taste, glutamate or nucleotides get in con-
`tact with their specific G protein–coupled receptor – GPCR (mGluR4
`– metabotropic glutamate receptor 4, TR1/TR3), which are pres-
`ent in the taste buds of the mammalian tongue (Nelson et al., 2002;
`Chaudhari et al. 2009). G- proteins are high- molecular mass com-
`pounds with different protein subtypes; each one has two subunits:
`Gα and Gβγ. One of the mechanisms earlier proposed suggested that
`substances responsible for umami activate the Gα subunit of GPCR.
`However, more recent investigations have shown that the main path-
`way for umami taste transduction seems to be related to the Gβγ sub-
`unit (Chaudhari & Roper, 2010).
`After the interaction between umami- GPCR, the βγ subunit dis-
`connects from the Gαβγ complex and activates the enzyme phospho-
`lipase C, leading to generate IP3 (inositol triphosphate). IP3 connects
`with calcium channels, existing in the endoplasmic reticulum, thus
`stimulating the opening and release of calcium (Ca++) through the cy-
`tosol. Calcium ions, now in elevated concentrations in the cytoplasm,
`connect with TRPM5 channels in the membrane, promoting the fast
`influx of sodium through the cell and, consequently, depolarizing the
`membrane. The combined action between the elevation of calcium
`and membrane depolarization provokes the opening of the gap junc-
`tions, which are probably composed by pannexins (Pax1), thus pro-
`moting the release of a large amount of ATP to the extracellular space
`(Chaudhari & Roper, 2010; Kinnamon, 2009).
`
`MALULY et AL.
`
` 20487177, 2017, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/fsn3.499 by Iowa State University Library, Wiley Online Library on [06/12/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
`
`Ex. 1187
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`

`

`The released ATP stimulates the afferent nerve fibers, and at the
`same time, they excite adjacent presynaptic cells, which promote the
`release of 5- HT (serotonin) and NE (norepinephrine), providing the
`gustative sensation in the brain. So far, it is known that if the taste
`buds are stimulated with umami substances, signals are reflected in
`the primary and orbitofrontal gustative cortex (de Araújo, Kringelbach,
`Rolls, & Hobden, 2003).
`The interactions between the sensations of umami and salty tastes
`were evaluated by Yamaguchi and Kimizuka (1979). The authors ver-
`ified that some intensification of the salty taste occurs when umami
`substances are present. The main impact is the increase in salivary
`secretion, smoothness and continuity of the flavor in the mouth.
`Nevertheless, the exact mechanisms of the gustative reception are not
`clear and need more investigation (Chaudhari & Roper, 2010).
`
`3 |  APPLICATION OF FLAVOR ENHANCERS
`AS A TOOL TO REDUCE SODIUM CONTENT
`IN SPECIFIC FOOD PRODUCTS
`
`Free glutamate occurs naturally in several foods, such as tomatoes,
`parmesan cheese, meats, peas, corn, mushrooms, and asparagus,
`among others. On the other hand, free glutamate may also be found
`in processed foods as a result of the use of MSG as a flavor enhancer
`(Yamaguchi & Ninomiya, 2000).
`Since the 1950s, flavor enhancers, such as MSG, have been used
`in Brazil. ANVISA allows the use of MSG in several meat products,
`canned vegetables, food service preparations and fillings, among oth-
`ers. For milk products, the use is allowed only in grated cheese. For
`all products, the regulation specifies the use as quantum satis (suffi-
`cient to obtain the desired technological effect) (ANVISA 2001, 2010,
`2015).
`In comparison to NaCl, glutamate salts such as MSG or monoammo-
`nium L- glutamate and disodium inosinate and guanylate, have low or
`no sodium content (Figure 1). There is an appropriate amount of MSG
`for NaCl replacement with maintaining acceptance of the food. This is
`because an excess of MSG does not promote the umami taste and, on
`the contrary, could lead to an undesirable sensation (Jinap & Hajeb,
`2010). The recommendation for MSG use as food additive is 0.1%–
`0.8% of weight, which corresponds to the amount of free L- glutamate
`present naturally in tomato or parmesan cheese (Beyreuther et al.,
`2007). For MSG, the amount of sodium is 12.28 g/100 g, and this is
`1/3 of the sodium when compared to NaCl (39.34 g/100 g). To use
`
`    |  1041
`
`MSG in a homemade recipe, such as 500 g of foodstuff (rice, minced
`meat, etc.), a simple replacement of 1/2 teaspoon of NaCl (2.5 g) by
`1/2 teaspoon of MSG (2.0 g) reduces sodium content in about 37%
`(Maluly, Pagani, & Capparelo, 2013).
`The following sections present potential applications of MSG to
`reduce sodium content in specific foods.
`
`3.1 | Soups
`
`Yamaguchi and Takahashi (1984) were some of the first research-
`ers who tested different concentrations of NaCl and MSG in soups
`with reduced sodium content. The authors evaluated sensory panels
`via the consumption of sumashi-jiru, a popular soup in Japan, made
`with dried bonito fish. The scales used by the sensory panels varied
`in a range of seven points that considered the amount of NaCl and
`palatability: from “extremely strong or palatable” (+3) to “extremely
`weak or unpalatable” (−3). Each panelist evaluated nine samples ran-
`domly and considered the concentration of 0.81 g/100 g of NaCl and
`0.38 g/100 g of MSG as an ideal formulation. The authors verified
`that the reduction in the NaCl amount did not affect the palatability of
`the salty taste. With these concentrations, it was possible to reduce
`sodium content and maintain acceptability. This research suggested
`that to increase the palatability of reduced sodium products, MSG
`content should be tested at fixed concentrations while varying the
`levels of NaCl until finding the most appropriate combination. This is
`the best strategy to reduce the total sodium content in soups without
`influencing their palatability.
`A recent study conducted by Jinap et al. (2016) investigated the ac-
`ceptance of a sodium reduction in spicy soups (curry chicken and chili
`chicken) by Malaysian panelists, replacing NaCl with MSG. The authors
`verified that MSG could maintain the acceptability of the soups. The
`high score of acceptability was given for the soups with 0.8 g/100 g
`and 0.7 g/100 g of NaCl and MSG, respectively. These amounts corrob-
`orate a previous study published by Yamaguchi and Takahashi (1984),
`who noted that MSG could reduce the sodium content by 32.5%.
`
`3.2 | Stocks and seasonings
`
`Stocks and seasonings containing NaCl are generally the main vehicles
`to elevate sodium consumption, according to the POFs (2002–2003
`and 2008–2009) (Sarno et al., 2009, 2013).
`To evaluate the acceptance of stocks and seasonings with low-
`sodium content, Rodrigues, Junqueira, et al. (2014) performed a
`
`F I G U R E   1  Structures and sodium
`content of monosodium glutamate
`monohydrate, disodium inosinate and
`disodium guanylate
`
`MALULY et AL.
`
` 20487177, 2017, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/fsn3.499 by Iowa State University Library, Wiley Online Library on [06/12/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
`
`Ex. 1187
`
`

`

`1042  |    
`
`sensorial evaluation with garlic seasonings in three recipes of rice with
`0%, 25% and 50% less NaCl. The seasonings were made with different
`proportions of NaCl, KCl (potassium chloride) and MSG. The authors
`verified that the panelists did not notice a strange or bad taste in the
`preparations, although it was reported that they contained less salt. In
`general, the preparations with less sodium were well accepted and the
`authors concluded that to these panelists, this choice could be a good
`alternative to reduce sodium content in homemade recipes.
`Since the first industrialized stock cube was created by Julius
`Maggi in 1863 in Switzerland, there have been significant modifica-
`tions on the formulations and consumption profile of this product. The
`western population is the largest consumer of stock cubes, mainly due
`to the convenience and flavor enhancement of the meals. However,
`NaCl is used in large concentrations in these products, which led to
`a fourth monitoring agreement to reduce sodium content, which was
`signed between the ABIA and the Brazilian Ministry of Health in 2013
`(IDEC 2014).
`MSG is commonly added to stock cubes since it can intensify the
`overall flavor and increase the impact, continuity and complexity of
`the final preparation. For stocks, the technological recommendation is
`15%–25%, and for seasonings, the recommended levels are 50%- 70%
`(when up to 10% NaCl is used) or 8%–10% (when more than 10% of
`NaCl is present in the product). These percentages can vary according
`to the ingredients added. Good Manufacturing Practices (GMP) are
`suggested in order to comply with the technological recommenda-
`tions and maintain the sensorial characteristics of foods (Maluly et al.,
`2013).
`A Malaysian study conducted with commercial products identified
`high concentrations of free glutamate in the chicken stock powder
`(170.90 ± 6.40 mg/g). The authors also verified that the high concen-
`trations were not from the addition of MSG alone but from the addi-
`tion of yeast extract. These concentrations were considered safe, but
`slightly high for some technological protocols. Therefore, sensorial and
`composition analyses are suggested so that reduced sodium prepara-
`tions do not exceed the technological limit of the umami taste sensi-
`tivity (Jinap & Hajeb, 2010; Khairunnisak, Azizah, Jinap, & NurulIzzah,
`2009).
`
`3.3 | Instant noodles
`
`Noodles are produced from wheat flour, buckwheat flour, rice flour
`or maize starch. These formulations can be modified according to the
`technology involved (Fu, 2008). Noodle dough needs NaCl, which has
`three different functions: gluten strengthening and elasticity, flavor
`and texture improvement, and the inhibition of microorganism growth
`and enzyme activation. Generally, 1%–3% and 8% NaCl are added to
`noodle formulations and Udon (a thick dough made with wheat flour
`or buckwheat), respectively (Fu, 2008). To rice flour noodles, which
`contain at least 7% protein, the main function of NaCl is to sustain the
`elasticity. Nevertheless, NaCl can reduce water penetration and in-
`crease the cooking time if the salt content is not controlled (Sangpring,
`Fukuoka, & Ratanasumawong, 2015).
`
`In addition to the use of NaCl in noodle dough, salt is also added in
`the seasoning. The analyses of 22 samples of instant noodles available
`in the Brazilian market raised a great concern mainly because the re-
`sults showed average levels of sodium content at 1,798 mg/100 g, with
`concentrations ranging between 1,435 mg/100 g and 2,160 mg/100 g
`when considering the overall product (dough + seasoning) and its re-
`constituted version (ANVISA 2012).
`The umami taste has a large impact in this kind of foodstuff since
`the seasonings are derived from meat and vegetables stocks, which
`are rich in glutamate, inosine and guanosine monophosphate. In the
`food industry, the use of umami substances in seasonings is extensive,
`and their recommended concentrations are 10–17 g/100 g for MSG
`or monoammonium glutamate (MAG), 0.5–0.7 g/100 g for disodium
`inosinate, and 0.3–0.7 g/100 g for the mixture of I + G (disodium ino-
`sinate + guanylate) (Maluly et al., 2013).
`In addition, it is suggested here that the technological recom-
`mendations concerning the use of flavor enhancers not be exceeded.
`Thereby, to reduce sodium in these products, the first approach is
`to create strategic government campaigns and warn the population
`about the reward of flavor variety in order to avoid food monotony,
`which will depend on consumption education and food behavior mod-
`ifications (Henney et al., 2010).
`
`3.4 | Meat products
`
`In general, meat products contain high sodium contents. NaCl is added
`for preservation purposes since it can prevent the growth of some
`pathogenic bacteria, extend the shelf life, ensure safety and tex-
`ture, and make the products softer (mainly lean meat) and with bet-
`ter flavor. Table 1 shows some processed meat products consumed
`in Brazil and their sodium contents, according to the Brazilian Food
`Composition Table (TACO, 2011).
`In an attempt to minimize the problems associated with high so-
`dium consumption, diverse protocols have been developed without
`compromising sensorial quality and the safety of meat products. Thus,
`Ruusunen, Simolin, and Puolanne (2001) verified an intensification of
`flavor when MSG, disodium inosinate (IMP) and guanylate (GMP) nu-
`cleotides were added to Bologna sausage formulations. The authors
`also demonstrated that even MSG added alone enhanced the senso-
`rial quality of the products. The salty taste sensation was improved in
`sausages with MSG.
`Quadros, Rocha, Ferreira, and Bolini (2015) evaluated the senso-
`rial profile of a fish (Mackerel) hamburger with reduced sodium. The
`hamburgers were formulated with whole minced fish after remov-
`ing residues via washing, such as hemoglobin and soluble proteins,
`which may interfere in the flavor and shelf- life of the preparations.
`The concentrations of 1.5 g/100 g and 0.75 g/100 g of NaCl as-
`sociated with 0.3 g/100 g of MSG were used in the different for-
`mulations. The results showed that MSG did not interfere directly
`with the final scores, but it contributed to the increase in accep-
`tance scores among products containing 0.75 g NaCl/100 g (50%
`reduction).
`
`MALULY et AL.
`
` 20487177, 2017, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/fsn3.499 by Iowa State University Library, Wiley Online Library on [06/12/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
`
`Ex. 1187
`
`

`

`T A B L E   1  Processed meat products and sodium content.
`
`Processed meat
`products
`
`Sodium
`content
`(mg/100 g)a
`
`Sodium
`content/
`portion (mg)
`
`Portion (g)b
`
`81
`1443
`5875
`869
`1252
`1090
`1126
`1374
`
`1351
`
`1176
`1432
`1456
`1212
`1021
`
`1039
`
`1574
`50
`125
`1256
`666
`
`Formed ham
`Jerked beef, cooked
`Jerked beef, raw
`Beef burger, raw
`Beef burger, fried
`Beef burger, grilled
`Chicken sausage, raw
`Chicken sausage,
`fried
`Chicken sausage,
`grilled
`Pork sausage, raw
`Pork sausage, fried
`Pork sausage, grilled
`Bologna sausage
`Cooked ham with fat
`covering
`Cooked ham without
`fat covering
`Salami
`Belly pork, raw
`Belly pork, fried
`Salty cod fish, braise
`Sardine, canned
`aValues from TACO (2011).
`bCalculation determined through the RDC nº 359, 12/23/2003 (ANVISA,
`2003).
`
`30
`30
`30
`80
`80
`80
`50
`50
`
`50
`
`50
`50
`50
`40
`40
`
`40
`
`40
`100
`100
`60
`60
`
`283
`433
`1763
`695
`1002
`872
`563
`687
`
`676
`
`588
`716
`728
`485
`408
`
`416
`
`630
`50
`125
`754
`400
`
`3.5 | Snacks
`
`In addition to potato chips, different kinds of snacks have emerged
`in the market, such as tortilla chips in Mexico and the US, pretzels in
`Italy and Germany, and popcorn, hazelnuts, nuts and seeds, and meat
`products, such as jerky in the US. Among Brazilian commercial snacks,
`other than potatoes, tortillas and extruded snacks, there are some
`nuts, such as peanuts and Brazil nuts.
`TACO (2011) provided the sodium content of some snacks. In
`salted roasted almonds only traces were found; concentrations at
`167 mg/100 g were verified in roasted and salty cashew nuts, whereas
`16 mg/100 g were reported in Brazil nuts. ANVISA (2012) reported
`levels of 1,092 mg/100 g in salty cassava flour biscuits, 779 mg/100 g
`in corn- extruded snacks, 741 mg/100 g
`in salty crackers and
`624 mg/100 g in potato chips.
`Brazilian customers are beginning to look for healthy snacks, such
`as those made with vegetables and with reduced sodium and fat con-
`tent (Barbosa, Madi, Toledo, & Rego, 2010). Consequently, the food
`industry has been trying to differentiate their products in this com-
`petitive market. Thus, flavor enhancers, as MSG, have been applied
`
`    |  1043
`
`in snacks to reduce sodium content. However, the total substitution
`of NaCl by flavor enhancers is not possible. Nevertheless, these sub-
`stances are used to harmonize the salty taste during taste perception.
`MSG stimulates the salivation and intensifies other flavors, such as
`aromas from certain herbs used in these products (Ainsworth &
`Plunkett, 2007).
`To reduce NaCl in snacks, the technological recommendation of
`MSG is up to 0.5 g/100 g. This is mainly due to the interactions with
`the salty taste and its property of covering- up the residual bitter taste
`promoted by NaCl substitutes, such as potassium chloride (Yamaguchi
`& Kimizuka, 1979).
`Attempts to use MSG in potato chips were made to reduce oil up-
`take and salt content. A solution containing NaCl (0.5 g/100 g) and
`MSG (0.03–0.3 g/100 g) was used in six different tests in vacuum con-
`ditions. Consequently, a transfer mass phenomenon was produced by
`the impregnation of the solutes into the potato and the loss of water
`from the pores. The entrance of the two solutes into the pores, par-
`tially substituting the water lost in the process, reduced the evapo-
`rated water bubbles inside the tissue. The fried potatoes, with 19%
`less water, consumed less heat flow (160–165°C) to change the vapor
`state, whereas a larger amount of sensitive heat was required to act
`in the dry matter, which favors the decrease in the oil flow into the
`pores. This could also lead to the decrease in acrylamide formation,
`which is desirable from a health and safety point of view and to the
`formation of a crunchy layer, which is desirable from a sensorial point
`of view. Furthermore, NaCl and MSG were used in low concentrations
`when compared to the usual conditions, reducing the sodium content
`(Silvera, 2013).
`
`3.6 | Milk products
`
`The direct addition of MSG is generally not applied in cheeses
`(ANVISA, 2015). Nevertheless, some researchers performed specific
`sensorial analyses to test flavor enhancer applications in mozzarella
`and cream cheese (Rodrigues, Gonçalves, Pereira, de Deus Souza
`Carneiro, & Pinheiro, 2014; Silva, de Souza, Pinheiro, Nunes, & Freire,
`2013).
`Three formulations of brines used for the preparation of Mozzarella
`cheese were evaluated: A (without reduced NaCl – 300 g/L); B (25%
`reduced NaCl – 225 g/L + 64.6 g/L of KCl + 40.2 g/L of MSG); C (50%
`reduced NaCl – 150 g/L + 43 g/L of KCl + 160.8 g/L of MSG). The
`formulations B and C resulted in a 30 and 54% sodium reduction, re-
`spectively. These reductions were obtained due to the diffusion coef-
`ficients of the salts in brines. After Time- Intensity (TI) evaluation of the
`salty taste and Temporal Dominance of Sensations (TDS) tests, it was
`possible to verify that the modifications of the sodium content did not
`affect the palatability significantly; however, a lower salty taste sen-
`sation was reported. The reduced sodium formulations were widely
`accepted, and the authors discussed that the use of MSG and other
`flavor enhancers in formulations containing KCl are crucial for avoiding
`bitter or metallic residues (Rodrigues, Gonçalves, et al., 2014).
`Cream cheese was investigated by Silva et al. (2013). Different
`types of NaCl substitutes were tested including KCl, magnesium and
`
`MALULY et AL.
`
` 20487177, 2017, 6, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/fsn3.499 by Iowa State University Library, Wiley Online Library on [06/12/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License
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`Ex. 1187
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`1044  |    
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`calcium chloride, calcium and potassium lactate, and potassium phos-
`phate. The authors found that KCl provided the highest salting equiva-
`lence when compared to NaCl, while MSG had a lower equivalence of
`salt. The partial substitution of NaCl by MSG intensified the salty taste
`according to the TDS test, giving the continuity of the sensation for
`8 min. Beyreuther et al. (2007) reported that flavor enhancers impart
`the umami taste and boost other flavors. Thus, researchers need to
`pay attention to their self- limiting addition of those food additives.
`
`4 |  SAFETY ASPECTS OF MONOSODIUM
`GLUTAMATE
`
`The available scientific data on the potential toxicity of MSG included
`studies on acute, subchronic and chronic, toxicity, as well as studies
`on teratogenicity and reproductive toxicity, in different animal species
`such as rats, mice, dogs, and rabbits. A detailed discussion on the re-
`sults of those studies was reported by Reyes, Areas, and Maluly (2013).
`
`4.1 | Toxicological aspects
`
`4.1.1 | Metabolism and pharmacokinetics
`
`After ingestion, glutamate is absorbed by the cells of the gastrointes-
`tinal tract and is catabolized in the cytosol and mitochondria by the
`transamination reaction under the action of various enzymes present
`in the stomach, intestines, and colon. One of the products of this ca-
`tabolism, α- ketoglutarate, can enter the tricarboxylic acid cycle, re-
`leasing energy (ATP) and carbon dioxide. Other metabolic products
`include lactate, glutathione, glutamine, alanine, and various other
`amino acids (Burrin & Stoll, 2009).
`Most of the glutamate present in foods (up to 95%) is metabo-
`lized by the first- pass effect and is used as an energy source by the
`enterocytes of the intestinal mucosa, whether it was added as a food
`additive or was naturally present in food (Reeds, Burrin, Stoll, & Jahoor,
`2000). Therefore, even after the ingestion of large amounts of protein
`in the diet, the glutamate levels in plasma are low due to its rapid me-
`tabolism in the intestinal mucosa cells. The ingested glutamate that is
`not metabolized in the gastrointestinal tract enters the hepatic portal
`circulation and is metabolized in the liver, generating energy via the
`Krebs cycle or being converted into urea for excretion in urine (Burrin
`& Stoll, 2009).
`The food components may also reduce the plasma concentration
`of glutamate when compared to the oral administration of the sub-
`stance in water, especially if the food is rich in metabolizable carbo-
`hydrates. These carbohydrates provide pyruvate as a substrate for
`glutamate in the mucosal cells, so more alanine is formed and less
`glutamate reaches the portal circulation (Stegink, Filer, & Baker, 1987).
`
`4.1.2 | Toxicity
`
`In tests performed with rats and mice, very low acute toxicity was
`verified after the oral administration of glutamate, with an LD50 (lethal
`
`dose that kills 50% of the animals studied) ranging from 10 to 22.8 g/
`kg bw (JECFA 1988; Walker & Lupien, 2000).
`JECFA (1988) evaluated subchronic and chronic toxicity studies
`conducted in rats and mice and that included the reproductive phase.
`Data showed that long- term exposure to MSG, when administered in
`the diet at up to 4.0%, did not elic