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Research, Society and Development, v. 10, n. 2, e51210212778, 2021
(CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i2.12778
1
Alkaline instant noodles: use of alkaline salts to reduce sodium and assessment of
calcium bioaccessibility
Macarrão instantâneo alcalino: uso de sais alcalinos para redução de sódio e avaliação da
bioacessibilidade do cálcio
Fideos instantáneos alcalinos: uso de sales alcalinas para reducir el contenido sodio y evaluación de
la bioaccesibilidad del calcio
Received: 02/08/2021 | Reviewed: 02/16/2021 | Accept: 02/17/2021 | Published: 02/27/2021
Ana Paula Rebellato
ORCID: https://orcid.org/0000-0002-7308-5127
State University of Campinas, Brazil
E-mail: paularebe@hotmail.com
Priscila Ferreira Tavares
ORCID: https://orcid.org/0000-0001-8570-9817
State University of Campinas, Brazil
pritavares04@gmail.com
Guilherme Neves Trindade
ORCID: https://orcid.org/0000-0003-0487-0129
State University of Campinas, Brazil
E-mail: guilherme.trindade@external.imerys.com
Juliana A. Lima Pallone
ORCID: https://orcid.org/0000-0002-8517-2922
State University of Campinas, Brazil
jpallone@fea.unicamp.br
Pedro H. Campelo
ORCID: https://orcid.org/0000-0003-1538-7941
Federal University of Amazonas, Brazil
E-mail: pedrocampelo@ufam.edu.br
Maria Teresa Pedrosa Silva Clerici
ORCID: https://orcid.org/0000-0002-8445-336X
State University of Campinas, Brazil
E-mail: mclerici@unicamp.br
Abstract
Instant noodles originated in eastern nations and have been accepted due to its practicality and low cost. However, its
high sodium content can lead to health problems. The present study aimed to reduce sodium and increase calcium levels
in noodles. A control (N1: K2CO3+ Na2CO3) and three treatments with the addition of calcium carbonate in combination
with alkaline salts such as potassium and sodium carbonates (N2: K2CO3+ CaCO3; N3: Na2CO3+ CaCO3; and N4:
CaCO3) were studied. Two hydration methods were investigated, and the technological characterization and the calcium
bioaccessibility of the different noodle formulations were determined. N4 did not fit into the alkaline noodle category
due to its neutral pH. N2 and N4 showed a sodium reduction of around 28% and a significant increase in calcium
content, with higher bioaccessible calcium. Significant changes were observed for the noodles made with the addition
of different alkaline salts, with a light-yellow color and better texture than the control, which can be a positive aspect,
once products with reduced nutrients usually present differentiated coloring. Therefore, the use of calcium carbonate
may be a promising alternative to increase Ca intake and to reduce the sodium content of instant noodles.
Keywords: Cereal product; Mineral bioaccessibility; In vitro digestion; Calcium; Sodium.
Resumo
O macarrão instantâneo é originário de países orientais e tem grande aceitação devido à sua praticidade e baixo custo.
No entanto, seu alto teor de sódio pode causar problemas de saúde. O presente estudo teve como objetivo a redução do
teor de sódio e aumento dos níveis de cálcio no produto. Um controle (N1: K2CO3 + Na2CO3) e três tratamentos com a
adição de carbonato de cálcio em combinação com sais alcalinos, como carbonatos de potássio e sódio (N2: K2CO3 +
CaCO3; N3: Na2CO3 + CaCO3; e N4: CaCO3) foram estudados. Dois métodos de hidratação foram investigados e a
caracterização tecnológica e a bioacessibilidade de cálcio das diferentes formulações de macarrão foram determinadas.
O N4 não se encaixou na categoria de macarrão alcalino devido ao seu pH neutro. N2 e N4 apresentaram redução de
sódio em torno de 28% e aumento significativo do teor de cálcio, com maior cálcio bioacessível. Mudanças
significativas foram observadas para o macarrão feito com a adição de diferentes sais alcalinos, com cor amarelo claro
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
(CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i2.12778
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e melhoria da textura em relação ao controle, o que pode ser um aspecto positivo, uma vez que produtos com nutrientes
reduzidos costumam apresentar coloração diferenciada. Portanto, o uso de carbonato de cálcio pode ser uma alternativa
promissora para aumentar a ingestão de Ca e reduzir o teor de sódio do macarrão instantâneo.
Palavras-chave: Produto à base de cereais; Bioacessibilidade de minerais; Digestão in vitro; Cálcio; Sódio.
Resumen
Originarios de las naciones orientales, los fideos instantáneos han sido aceptados debido a su practicidad y bajo costo.
Sin embargo, su alto contenido en sodio puede provocar problemas de salud. El presente estudio tuvo como objetivo
reducir el contenido de sodio y aumentar los niveles de calcio en los fideos. Para ello, se estudiaron una muestra control
(N1: K2CO3 + Na2CO3) y tres tratamientos con adición de carbonato de calcio en combinación con sales alcalinas de
carbonato de potasio y sodio (N2:K2CO3 + CaCO3; N3:Na2CO3 + CaCO3; y N4:CaCO3). Se investigaron dos métodos
de hidratación, asimismo, se realizó la caracterización tecnológica y se determinó la bioaccesibilidad del calcio de las
diferentes formulaciones de fideos. N4 no encajó en la categoría de fideos alcalinos debido a su pH neutro. N2 y N4
experimentaron una reducción alrededor del 28% de sodio y un aumento significativo del contenido y bioaccesibilidad
de calcio. Se observaron cambios significativos en los fideos elaborados con la adición de las diferentes sales alcalinas,
como un color amarillo claro y mejor textura en comparación al control, lo que puede ser un aspecto positivo dado que
los productos con reducción nutrientes suelen presentar una coloración diferenciada. Por tanto, el uso de carbonato de
calcio puede ser una alternativa prometedora para aumentar la ingesta de Ca y reducir el contenido de sodio en fideos
instantáneos.
Palabras clave: Producto de cereales; Bioaccesibilidad mineral; Digestión in vitro; Calcio; Sodio.
1. Introduction
People with chronic non-communicable diseases are at high risk of severe Covid-19, including hypertension and heart
disease (Hobbs, 2020; Hoover, 2020). Thus, sodium reduction is required in easy-to-make foods, especially those packaged for
single-use, once the quarantine led to an increase in the food-at-home consumption of these products (Hoover, 2020). In this
context, instant noodles have stood out, which have shown an increased demand in the Brazilian market, with consumption of
0.129 kg/inhabitant in 2019 (Abimapi, 2020).
It is believed that instant noodles originated in China in 5000 B.C. However, the first instant noodles were made in
Japan in 1958, and have become widely consumed by the eastern and western populations (Fu, 2008; Han et al., 2012). According
to the World Instant Noodles Association (Wina, 2020), the world’s largest consumer of noodles is China/Hong Kong, with a
record intake of 41.45 million servings in 2019, followed by Indonesia with 12.52 million servings. The main reasons for
widespread popularization include practicality, long shelf-life, and low cost (Fu, 2008; Gulia et al., 2014). However, they are
considered products with high fat and sodium contents, which do not meet the current guidelines for healthy eating.
Instant noodles are mainly made from wheat flour, starch, water, salt, or kansui (a mixture of sodium and potassium
carbonates and phosphates) and other ingredients to improve texture, color, and flavor (Gulia et al., 2014; Kruger et al., 1996).In
general, the manufacturing process of noodles includes lamination and cutting, followed by cooking and frying (Fu, 2008).The
final product should contain 15 to 20% fat, which can lead to greater susceptibility to lipid oxidation of the product during the
storage (Gulia et al., 2014). Studies have suggested the use of different drying methods, such as microwave radiation, infrared,
and hot air, to produce noodles with reduced fat content (Ismailoglu & Basman, 2016; Pongpichaiudom & Songsermpong, 2018;
Wang et al., 2011).
Sodium is considered an essential element for human life and has relevant technological and sensory functions in food
products (Orlando et al., 2020). However, its excessive consumption is associated with the development of chronic diseases,
such as hypertension, cardiovascular, and kidney diseases, among others (Nilson et al., 2012). The consumption of instant
noodles provides more than 700 mg of sodium per serving, which corresponds to approximately 29% of the recommended daily
intake. Therefore, studies on salt-reduced noodles are necessary, aiming to reduce the risk of developing diseases related to high
sodium intake (Gropper et al., 2011; Park et al., 2011).
In this context, the replacement of sodium for calcium in noodles can be an interesting alternative since calcium is an
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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essential mineral for the functioning of the human body. Its function is closely associated with the construction and maintenance
of bones and teeth, while its deficiency can cause osteoporosis, and long-term deficiency can lead to hypertension, colon cancer,
and obesity (Gropper et al., 2011).
Some authors have studied the replacement of sodium by calcium carbonate in different food matrices such as bread,
coffee, and soy beverages, among others, as calcium carbonate is an inexpensive and available source of calcium (Gulia et al.,
2014; Kajishima et al., 2003; Paula, 2013; Umbelino et al., 2001). However, studies on the use of calcium carbonate in instant
noodles and the calcium bioaccessibility have not been found in the literature.
Mineral bioaccessibility has been investigated in different food matrices, as it can estimate, through in vitro tests, the
availability of an element of interest to be absorbed by the human body (Cámara et al., 2005; Miller et al., 1981; Rebellato et al.,
2015; Sahuquillo et al., 2003; Silva et al., 2020). The in vitro dialysis assay allows evaluating the transport of nutrients through
the use of a semipermeable membrane with defined pore sizes, similar to the intestinal pores. The method also allows determining
the time required for the material to move through the gastric and intestinal phases, with changes in pH, agitation, and temperature
to simulate the human body (Alegría-Torán et al., 2015; Miller et al., 1981; Perales et al., 2006).
Thus, in the present study, instant noodles were made with the addition of calcium carbonate and different combinations
of alkaline salts, such as potassium and sodium carbonates, aiming at reducing sodium and increasing calcium in the
formulations. The technological characterization and the evaluation of calcium bioaccessibility in the different formulations were
also performed.
2. Methodology
2.1 Materials
For the production of alkaline instant noodles, wheat flour type 1 enriched with iron and folic acid was donated by
Pastificio Selmi (Sumaré, São Paulo), vegetable fat, potassium carbonate, and sodium carbonate were purchased in the local
market, and calcium carbonate (I-Blum F22) was donated by Imerys do Brasil.
For calcium quantification, the following reagents were used: nitric acid, and hydrogen peroxide (Sigma-Aldrich, USA;
Merck, Germany); calcium standard solution 1000 mg/Kg (Qhemis, Jundiaí, Brazil); purified water; and black ribbon
quantitative filter paper. For the bioaccessibility assay, pepsin (P-7000), pancreatin P-7545, bile salts extract (B-8631), and cut-
off dialysis membranes (12,000 Da and 25 Å) were purchased from Sigma Chemical Co. (St Louis, MO, USA),
The mineralized samples were evaluated by flame atomic absorption spectrometer (FAAS), model AAnalyst 200
(PerkinElmer). For the evaluation of calcium mineral, the equipment was operated in absorption mode, with hollow cathode
lamps (422.67 nm). Each sample was placed into the nebulizer and mixed with air-acetylene flame (2.5/10 L/h) at approximately
2000 °C.
2.2 Methods
2.2.1 Manufacture of instant noodles with different combinations of alkaline salts
The wheat flour was submitted to a mixing stage (mixer KitchenAid - Professional) and after 2 minutes, water and
previously dissolved salts were added, with homogenization for another 13 minutes until forming a homogeneous mixture. Then,
the mixture remained at rest for 10 minutes, followed by lamination in an automatic cylinder (Pastaia 2, BRALYX, Poleto, and
Partners), with a gradual reduction of the spacing between the cylinders until reaching 1.2 mm thickness. The dough was cut 0.9
mm wide in the same equipment and portioned at 25 ± 0.50 g for cooking in a steam oven at 120 °C for 3 minutes (PRÁTICA,
Technipan). Then, the dough was oven-baked (25 ± 1 °C) for 1 hour and 30 minutes, and deep-fat fried at 130 °C for 30 seconds
(Sina, Vegetal Fry 32). The noodle was exposed to ventilation for 10 minutes, packed in plastic packages, and stored at a
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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controlled temperature in absence of light. Four noodle formulations were made, using 1.5% NaCl, 1% alkaline salts, and 38%
water, calculated based on the amount of wheat flour (100%) and different sodium carbonate concentrations, as follows: control
N1 containing 0.50% K2CO3+ 0.50% Na2CO3; formulation N2containing 0.50% K2CO3+ 0.50% CaCO3; formulation N3
containing 0.50% Na2CO3+ 0.50% CaCO3; and formulation N4 containing 1% CaCO3.
2.2.2 Technological characterization of instant noodles with different combinations of alkaline salts
The moisture content was determined according to the method 44-15.02 of AACCI (2010); fat content was calculated
through the mass balance, considering the moisture values before and after frying; water activity (aw) was measured in a 4 TEV
Aqualab apparatus (Decagon Devices, Inc., Pullman, Washington, USA), solid loss was determined according to the method 16-
50 of AACC (2000), with modifications by Gull et al. (2015); the nutritional composition was estimated according to the
nutritional composition of the ingredients; and pH was determined according to the Analytical Standards of the Adolfo Lutz
Institute (IAL, 2008).
2.2.3 Color measurements
The color parameters L*, a*, and b* were determined using a MiniScan XE portable colorimeter (Hunter Associates
Laboratory, Inc., Reston, Virginia, USA), with D65 illuminant, and 10 ° observation angle.
2.2.4 Texture profile analysis
The texture profile of fried noodles and hydrated noodles was analyzed according to the method 66-50 of AACC (1999),
with the aid of the TA-XT2 texture analyzer, with a load of 50 kg (Stable Micro Systems, Surrey, England). The force and
compression parameters were determined, using pre-test speed = 0.50 mm/s, test speed = 1.70 mm/s, post-test speed = 10.00
mm/s, and distance = 40%.
2.2.5 Calcium bioaccessibility of instant noodles with different combinations of alkaline salts
To quantify the calcium content, 80.37 ± 0.53g of sample was cooked in 450 mL of boiling water for 3 minutes. The
samples were transferred to glass containers and cooled to room temperature. Then, aliquots of 10 mL of the cooking water were
used to determine the soluble calcium content during cooking. The remaining mixture (water and noodle) was homogenized in
a food processor to determine the calcium content.
The quantification of total and dialysate calcium was performed as described by Rebellato et al. (2015). For that, 0.60
g of sample was placed indigestion tubes and 8 mL of nitric acid and 2 mL of hydrogen peroxide was added and subjected to
digestion in a block digester for 2 hours at 110ºC. Subsequently, the tubes were sonicated, the contents transferred to a 25 mL
volumetric flask, and filtered. The quantification was performed by flame atomic absorption spectrometry.
The dialysis assay was performed as described by Rebellato et al. (2015), with modifications. For that, 5g of sample
was homogenized with 30 mL of ultra-pure water, and the pH was adjusted to 2.00 using 6 mol/L HCl. The gastric stage initiated
with the addition of 0.65 mL of pepsin solution in 0.10 mol/L HCl, and incubation in a metabolic bath at 37 ºC for 2h.
At the end of the gastric stage, the sample was removed from the metabolic bath and placed in an ice bath for 10 minutes.
Then, 6.50 mL of the pancreatin-bile mixture solubilized in 0.10 mol/L NaHCO3 was added to the digest, followed by titration
using 0.50 mol/L NaOH until pH 7.20. After knowing the molar equivalent in 0.50 mol/L NaHCO3, the dialysis membranes
were filled with 0.50 mol/L NaHCO3 and the volume was filled with ultra-pure water (30 mL). The membranes were placed in
the flasks containing the digest and incubated for 30 minutes. Then, 6.50 mL of the pancreatin-bile mixture was added to the
flasks and incubated for a further 2 h at 37 °C. After incubation, the membranes were removed from the flasks, washed with
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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ultra-pure water, and the dialysate was transferred to digestion tubes and incubated in an oven at 100 °C for 24 h. After the
volume reduction, the samples were digested in an acid medium (8 mL of nitric acid and 2 mL of hydrogen peroxide), in a
digester block for 2 h at 110ºC. Subsequently, calcium was quantified by atomic absorption. The determinations were performed
in four repetitions.
2.2.6 Statistical analysis
All analysis were performed in triplicate, except for the bioaccessibility assay, which was performed in four replications.
The results were expressed as mean ± deviation. The means were evaluated by the Scott-Knott test, using the SISVAR software
(version 5.6 - Build 86) and t-Student test, using the XLSTAT software (version 2018.2.50634).
3. Results and Discussion
3.1 Manufacture of instant noodles with different combinations of alkaline salts
During manufacture, the noddle formulations N2 to N4 containing calcium carbonate showed better machinability,
when compared to the control (N1), which facilitated the lamination step. This result may be due to a strengthening of the gluten
network since calcium carbonate can also act as a dough conditioner (Smith & Hong-Shum, 2011).
After the manufacture of the noodles, a color difference was observed for the formulations N2 to N4, which exhibited
a lighter yellow color when compared with the formulation N1, probably due to different pH values. The lighter color of calcium-
containing noodles can be a positive aspect, as products with reduced nutrients present light color, as a way to show the rapid
changes to consumers. Regarding the integrity of the pasta threads, no differences were observed between the formulations.
3.2 Technological characterization of instant noodles with different combinations of alkaline salts
The parameters evaluated in the technological characterization are shown in Table 1. The moisture content is an
important parameter, not only for microbiological control but also as an indicator of quality (Yu & Ngadi, 2004). Although the
results of fried noodles were in accordance with the Brazilian legislation, which has established moisture contents lower than
10% for instantaneous pasta (Brasil, Ministério da Agricultura, 2000), the formulations N3 and N4 showed a higher moisture
content and differed significantly from N1 and N2. This result demonstrates that calcium carbonate, when used alone or in
combination with other alkaline salts (Na2CO3), contributed to greater water retention in the final product, probably due to the
anti-humectant capacity of calcium carbonate (Brazil, 2010).
The fat content was calculated by mass balance, through the difference between the moisture values before and after
frying, once the water molecules form channels allowing the passage of fat into the product (Hou, 2001). Before frying or just
after the steaming stage, the moisture content of the noodle formulations varied from 15.53% to 18.47%. Right after the frying
step, the moisture content varied from 6.09% to 7.82%, and the fat content ranged from 9.18% to 10.64%, with no significant
differences between the samples.
Regarding the water activity (aw), the values were close to those reported in the literature, which establishes values
close to 0.50 for fried alkaline instant noodles (Hou, 2010). Although the formulations N3 and N4 had the highest moisture
values, they presented the lowest aw values when compared to the control. No significant differences were observed for the
moisture content of the formulation N2 when compared with the control; however, it presented lower aw than N1, that is, the
water retained by calcium carbonate was not free for microbiological growth, thus with no impact on the shelf life of the product.
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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Table 1. Technological characteristics of alkaline instant noodle with different combinations of alkaline salts1
Samples
Parameters
N1
N2
N3
N4
Fried alkaline
instant noodle
Moisture (%)
6.09 ± 0.48b
6.41 ± 0.16b
7.27± 0.18a
7.82 ± 0.39a
Theoretical percentage of fat
(%)
9.43 ± 1.89n.s.
9.18 ± 1.90n.s.
9.54 ± 1.47n.s.
10.64 ± 1.71n.s.
Water activity (aw)
0.61 ± 0.00a
0.55 ± 0.00c
0.56 ± 0.00b
0.56± 0.00b
pH
10.37 ± 0.27a
9.30 ± 0.11c
9.59 ± 0.01b
7.45 ± 0.02d
Hydrated alkaline
instant noodle
Solid loss (g/100g)
conventional method
6.24 ± 0.00n.s.
7.42 ± 0.24n.s.
6.35 ± 1.21n.s.
7.27 ± 0.19n.s.
Solid loss (g/100g) microwaves
2.20 ± 0.29n.s.
3.16 ± 0.17n.s.
2.24 ± 0.33n.s.
3.59 ± 0.62n.s.
1Results are presented as mean ± standard deviations. N1: 0.50% K2CO3:0.50% Na2CO3; N2: 0.50% K2CO3:0.50% CaCO3; N3: 0.50% Na2CO3:0.50% CaCO3;
N4: 1% CaCO3. Means followed by different letters on the same line differ significantly from each other by the Scott-Knott test (p <0.05). Means followed by
* in the same column differ significantly by Student’s t-test (p-value<0.05) between Solid loss of alkaline instant noodle hydrated by conventional method and
microwaves; n.s.: not significant.
Source: Authors.
Concerning solid loss during cooking, the noodles hydrated by microwave radiation showed the lowest values when
compared to those hydrated by the conventional method. Although the solid loss may be lower than 10% for starch noodles,
small losses are desirable (Tan et al., 2009). In addition, the solid loss is a consequence of several process parameters, such as
mixing time, dough thickness, cooking temperature, and frying conditions (Gulia & Khatkar, 2013). However, these parameters
were fixed in this study to prevent possible interferences.
Table 2 shows the estimated nutritional composition, with emphasis on the sodium and calcium contents. The
formulations N2 and N4 showed a reduction in the sodium content of 28% and 30%, respectively, when compared with N1. In
turn, the formulations N2, N3, and N4 showed an increase in calcium content, positively impacting the recommended daily
intake by 10%, 9%, and 19%, respectively.
Studies have shown that the consumption of instant noodles is directly associated with higher sodium intakes (Park et
al., 2011) and consequently, an increase in the development of chronic non-communicable diseases, such as heart attack and
stroke. Therefore, the use of a combination of salts, such as the present study, or the partial replacement of sodium by calcium
carbonate can be an interesting alternative for the instant noodles industries, which can partially replace sodium for another salt
with less negative health impacts.
Concerning the pH values, the formulations N1 to N3 showed alkaline pH, while N4 had neutral pH, thus classified as
a common noodle rather than alkaline noodle. The pH range for alkaline noodles should remain from pH 9 to 11 (Hou, 2001).
The pH is directly related to the color of the product, due to the presence of flavonoid compounds in wheat flour, exhibiting
yellow color in an alkaline environment, which increases with increasing the pH values (Hou, 2001).
3.3 Color measurements in instant noodles with different combinations of alkaline salts
The luminosity (L*) and chromaticity (a* and b*) parameters were determined to assess the color of the different noodle
formulations, as shown in Table 3. No significant differences in luminosity were observed for the fried formulations N1, N2,
and N3, whereas the formulation N4 presented the highest luminosity and differed from the other formulations. Similar behavior
was observed for the formulations hydrated by both conventional and microwave methods. Concerning the parameter a*, which
corresponds to red (+ a) and green (-a), the formulations N1 and N4 showed more reddish color when compared with N2 and
N3. After hydration by the conventional and microwave methods, an increase in a* values were observed for the formulations
N1, N2, and N3, while a decrease of this coordinate was observed for N4 when compared to the fried noodles. Regarding the
parameter b*, which is related to yellow (+b) and blue (-b), the fried noodles showed a reduction in yellow color from N1 to N4,
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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which was also observed for samples hydrated by microwaves. For the conventional hydration method, only the formulation N4
showed a reduction in yellow color, with no differences between the other formulations.
Table 2. Estimated nutritional composition of alkaline instant noodle with different combinations of alkaline salts1
N1
N2
N3
N4
Parameters
Amount
per
serving
(80g)
DV (%)
Amount
per
serving
(80g)
DV (%)
Amount
per
serving
(80g)
DV (%)
Amount
per
serving
(80g)
DV (%)
Calories (kcal)
212.39
11
209.19
10
214.04
11
209.67
10
Carbohydrate (g)
37.63
13
37.27
12
37.84
13
36.23
12
Protein (g)
4.95
7
4.90
7
4.98
7
4.77
6
Total fat (g)
4.67
8
4.50
8
4.75
9
5.07
9
Saturated fat (g)
1.07
5
1.04
5
1.09
5
1.17
5
Unsaturated fat (g)
3.60
**
3.47
**
3.66
**
3.91
**
Dietary fiber (g)
0.99
4
0.98
4
1.00
4
0.95
4
Sodium (mg)
399.37
17
289.07
12
401.54
17
281.03
12
Iron (mg)
2.08
15
2.06
15
2.09
15
2.00
14
Calcium (mg)
0.00
0
98.07
10
94.46
9
190.69
19
Folic acid (μg)
74.28
19
73.56
18
74.68
19
71.51
18
1 N1: 0.50% K2CO3:0.50% Na2CO3; N2: 0.50% K2CO3:0.50% CaCO3; N3: 0.50% Na2CO3:0.50% CaCO3; N4: 1% CaCO3; DV: % Daily
Values are based on a 2000 kcal or 8400 kJ. ** not established.
Source: Authors.
Table 3. CIE Lab L*, a*, and b* values of fried and hydrated alkaline instant noodle with different combinations of alkaline salts1
Samples
Parameters
N1
N2
N3
N4
Fried
L*
57.42b ± 3.55
60.39b ± 1.37
59.22b ± 2.32
65.87a ± 1.36
a*
2.27a ± 0.96
0.41b ± 0.05
0.70b ± 0.53
1.91a ± 0.05
b*
32.44a ± 1.40
27.10b ± 0.40
28.77b ± 1.55
20.14c ± 0.80
Hydrated by
conventional
method
L*
61.25c ± 1.97
68.15b ± 2.07
66.88b ± 1.46
76.05a ± 0.28
a*
5.21a ± 1.21
1.15b ± 0.53
1.64b ±0.27
0.99b ± 0.14
b*
32.11a ± 0.65
29.62a ± 0.91
30.31a ± 1.75
18.92b ± 0.90
Hydrated by
microwaves
L*
61.35c ±0.24
70.68b ± 2.50
69.85b ± 0.93
77.11a ± 0.54
a*
4.41a ± 0.45
1.45c ± 0.23
2.14b ± 0.44
1.43c ± 0.06
b*
29.83a ± 1.38
26.51b ± 0.97
27.99b ± 0.75
19.28c ± 0.14
1Results are presented as mean ± standard deviations. N1: 0.50% K2CO3+0.50% Na2CO3; N2: 0.50% K2CO3+0.50% CaCO3; N3: 0.50%
Na2CO3+0.50% CaCO3; N4: 1% CaCO3. Means followed by different letters on the same line differ significantly from each other by the
Scott-Knott test (p-value < 0.05).
Source: Authors.
The presence of flavonoid compounds in wheat flour is not the only factor that can interfere with the color intensity of
the final product, which can be affected by other factors including the grinding degree, the levels of starch, and the protein
content of wheat flour (Asenstorfer et al., 2006; Baik&Czuchajowska, 1995; Ye et al., 2009). Therefore, the addition of natural
dyes, such as β-carotene, is a common practice in the production of commercial noodles as only the characteristics of the flour
is not sufficient to achieve the desired color intensity. Thus, the light-yellow color of N4 can be prevented with process
adjustments.
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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3.4 Texture profile of instant noodles with different combinations of alkaline salts
As can be seen in Table 4, no significant differences were observed for the firmness values between the fried noodles.
Regarding the formulations subjected to hydration by the conventional method, loss of firmness was reduced for N2 to N4 when
compared to the control (N1). For the treatments hydrated by microwaves, a significant difference in firmness was observed for
N3 and N4 when compared to the control. Interestingly, the formulation N4, made with the addition of sodium carbonate, was
less firm or softer than the other formulations, probably due to the anti-humectant characteristic of calcium carbonate. It is worth
mentioning that texture is a subjective parameter, as it depends on consumers’ preference, which can vary from one country to
another (Hou, 2001).
Table 4. Texture parameters of fried and hydrated alkaline instant noodle with different combinations of alkaline salts1
Parameters
N1
N2
N3
N4
Firmness
(N)
Fried
63.56 ± 8.17n.s.
48.31 ± 19.56n.s.
41.88 ± 5.21n.s.
54.54 ± 16.90n.s.
Hydrated by
conventional method
1.37± 0.10a
1.25 ± 0.16b
1.10 ± 0.12c
0.79 ± 0.05d
Hydrated by microwaves
1.67 ± 0.24a
1.53 ± 0.19a
1.32 ± 0.12b
0.89 ± 0.16c*
Time until the fried samples reached
the maximum firmness (s)
4.26 ± 1.47b
6.07 ± 0.95a
4.94 ± 1.82b
6.03 ± 1.09a
1Results are presented as mean ± standard deviations. N1: 0.50% K2CO3+0.50% Na2CO3; N2: 0.50% K2CO3+0.50% CaCO3; N3: 0.50%
Na2CO3+0.50% CaCO3; N4: 1% CaCO3. Means followed by different letters on the same line differ significantly from each other by the Scott-
Knott test (p-value<0.05). Means followed by * in the same column differ significantly by Student’s t-test (p <0.05) between the noodle hydrated
by conventional method and microwaves.
Source: Authors.
Concerning the fried noodles, the time to reach the maximum firmness was also evaluated, which was calculated through
graphs generated during the analysis. The formulations N1 and N3, which contained Na2CO3, reached the maximum firmness
within four seconds, while the formulations N2 and N4 with the addition of CaCO3 required a longer time to reach maximum
firmness. The addition of calcium carbonate in the formulations N1 and N3 provided greater resistance to breakage, suggesting
that its use may reduce breakage during processing, which is one of the main challenges of the instant noodle industry.
3.5 Calcium bioaccessibility of instant noodles with different combinations of alkaline salts
Before performing the bioaccessibility assay, all noodle formulations were cooked, according to Section 2.2.5, and the
calcium (Ca) content in the cooking water was determined. The Ca levels varied from 0.35 to 4.01 mg/100g, with the higher and
the lower loss of calcium during cooking observed for the control (N1) and the formulation N2, with values of 13% and 0.64%,
respectively (Table 5). The calcium content of the cooking water is dependent on the salt used in the formulations. However, as
instant noodles are prepared and consumed along with the cooking water, all tests were performed for the mixture noodle +
cooking water.
The total calcium of the noodle formulations ranged from 3.78 to 88.47 mg of calcium per 100g of sample. The control
presented lower total calcium levels when compared with that reported by the Brazilian Food Composition Table (18 mg/100g)
(Nepa, 2011), probably due to various factors, including the different cultivar, climatic conditions, and the flour extraction rate
(Afridi et al., 2011). In certain countries, such as the United Kingdom, the fortification of ground (white) flour with calcium to
restore the calcium levelof whole flour is mandatory (Marcovecchio et al., 2015). The sample preparation for analysis may also
have contributed to the divergence of these values. However, the use of alkaline salts in instant noodle formulations led to a
significant increase in calcium contents, which can contribute to the intake of this mineral.
When simulating the gastrointestinal digestion through the dialysis assay of the instant noodles, both the control and
the formulation N3 exhibited lower dialyzed calcium levels when compared with the quantification limit (0.25 mg/100g). On the
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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other hand, the formulations N2 and N4 presented dialyzed calcium contents of 3.69 and 2.89 mg/100g, respectively.
Table 5. Calcium bioaccessibility of alkaline instant noodle with different combinations of alkaline salts1
Samples
Calcium content (mg/100g)
% dialysis
Total
Dialyzed
N1
3.78 ± 0.37
< 0.25
*
N2
54.47 ± 0.13
3.69 ± 0.40
6.78a
N3
52.92 ± 0.60
< 0.25
*
N4
88.47 ± 1.35
2.89 ± 0.27
3.27b
1Results are presented as mean ± standard deviations. N1: 0.50% K2CO3+0.50% Na2CO3; N2: 0.50% K2CO3+0.50% CaCO3; N3: 0.50%
Na2CO3+0.50% CaCO3; N4: 1% CaCO3. Means followed by different letters on the same line differ significantly from each other by the
Scott-Knott test (p < 0.05).
Source: Authors.
It is worth mentioning the impact of the association between calcium carbonate and potassium carbonate, which
increased the percentage of dialyzed calcium in N2, even when the amount of calcium added was lower when compared to the
formulation N4.
Higher total and dialyzed calcium contents were expected in the samples due to the calcium source used, calcium
carbonate, which presented 51.42% of dialyzed calcium when analyzed outside the food matrix. However, calcium loss during
the pre-cooking and frying steps may have occurred. No data were found in the literature that can be correlated with the present
study. Several technological steps are involved in the manufacture of instant noodles, including mixing, cutting, pre-cooking,
frying, drying, and packaging. These processing steps as well as the digestive process can lead to complex interactions between
minerals and the food matrix components, with positive or negative effects on the bioavailability of nutrients (Marcovecchio et
al., 2015).
One hypothesis for the low dialyzed calcium content of the formulations containing sodium carbonate, N1 and N3, is
the presence of a greater amount of sodium ions from the NaCl added to the formulation, in addition to Na2CO3. This fact may
have contributed to a greater development of the gluten network, with a lower content of dialyzed calcium found in the
bioaccessibility assay.
The fat used in the deep fat-frying may have also affected the low bioaccessible calcium levels. In the digestive process,
carbohydrates, proteins, and lipids are degraded through specific conditions and enzymes, leading to the formation of new bonds
and alteration of existing bonds, thus affecting their affinities with metal ions (Lorieau et al., 2018). It is known that the calcium
absorption rate is influenced by the type of fat used during frying, leading to the formation of insoluble, non-absorbable calcium
soaps with long-chain fatty acids. Therefore, during the frying process, free calcium tends to bond with the fat and form soap,
thus becoming less bioaccessible (Lorieau et al., 2018).
In addition, each calcium compound has a different solubility and is dependent on the pH of the environment, with
maximum solubility generally achieved under acidic conditions. During the digestive process, pH can change from an acidic
environment (gastric digestion) to a neutral environment (enteric digestion) (Lorieau et al., 2018). Studies have shown the total
solubility of different calcium salts (glycerophosphate, carbonate, phosphate, citrate, and oxalate) at pH 3. However, in the
enteric stage, the calcium solubility decreases with an increase in pH to 7 (Goss et al., 2007; Lorieau et al., 2018). The increase
in pH can lead to the formation of a calcium precipitate with a molecular weight greater than the membrane pore size used for
dialysis, which may have reduced the amount of calcium available to cross the semipermeable membrane.
The dialysis method (in vitro) is based on the simulation of gastrointestinal digestion, followed by the quantification of
the element of interest, which crosses a semipermeable membrane simulating the intestinal wall, under controlled conditions of
Research, Society and Development, v. 10, n. 2, e51210212778, 2021
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temperature, agitation, pH, and presence of enzymes. There are no studies on the use of calcium salts in instant pasta and
bioaccessibility assessment. Although the simulated gastrointestinal digestion through the dialysis assay does not represent the
complexity of the human digestive process, it has been used to estimate the availability of nutrients present in food, correlating
with in vivo tests (Hur et al., 2011).
4. Conclusion
The present results showed that the instant noodle formulationN2 made with the combination of calcium and potassium
carbonates resulted in a quality product suitable for consumption. It presented satisfactory technological characteristics, with a
reduction of 28% sodium when compared with the control, and similar color characteristics to the other formulations. In addition,
it presented hydration behavior similar to the control, greater resistance to breakage, and maintenance of alkaline pH values,
characterizing the product as an alkaline instant noodle. Although the formulation N2 presented lower calcium content when
compared to N4, it was more bioaccessible, with values 2 to 7 times higher when compared to the other treatments. Thus, the
use of calcium carbonate in alkaline instant noodles has proven to be a promising alternative to increase Ca intake and to reduce
the sodium levels of the final product.
Acknowledgments
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES)
– Finance Code 001. The authors also thank the scholarship awarded for the students Priscila Tavares and Guilherme, the
Pastificio Selmi for donating the wheat flour, and Imerys do Brasil for donating calcium carbonate.
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