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International Food Research Journal 23(5): 2181-2186 (2016)
Journal homepage: http://www.ifrj.upm.edu.my
1Tan, W. L., 1,2,3*Azlan, A. and 4Noh, M. F. M.
1Department of Nutrition and Dietetics, Faculty of Medicine and Health Sciences, Universiti Putra
Malaysia, 43400 UPM Serdang, Selangor, Malaysia
2Laboratory of Analysis and Authentications, Halal Products Research Institute, Universiti Putra
Malaysia, 43400 UPM Serdang, Selangor, Malaysia
3Research Centre of Excellence for Nutrition and Non-Communicable Disease, Faculty of Medicine
and Health Sciences, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
4Nutrition Unit, Cardiovascular, Diabetes and Nutrition Research Centre, Institute for Medical
Research, Jalan Pahang, 50588 Kuala Lumpur, Malaysia
Sodium and potassium contents in selected salts and sauces
Abstract
The study was undertaken to determine and compare the sodium and potassium contents in
selected salts (table salt, coarse salt, French sea salt, Himalayan pink salt and bamboo salt)
and sauces (light soy sauce, sweet soy sauce, chili sauce, tomato sauce and mayonnaise).
Findings of the present study showed that the sodium content of salts was highest in table salt
(35870.0 mg/100 g) and lowest in French sea salt (31235.0 mg/100 g), whereas the potassium
content was highest in bamboo salt (399.4 mg/100 g) and lowest in table salt (43.7 mg/100
g). There was no signicant difference between sodium amounts of the salts. Bamboo salt
was signicantly higher in potassium than other salts. The ranking of sodium and potassium
in sauces was similar, where light soy sauce contained the highest amount (4402.0 and 395.4
mg/100 g) and mayonnaise contained the least (231.3 and 63.6 mg/100 g). Both sodium and
potassium contents of light soy sauce were signicantly higher than other sauces. Bamboo salt
is a better choice instead of other salts in terms of the potassium level. Among sauces, although
light soy sauce is high in potassium; however, its high sodium has offset the benecial effect
of potassium.
Introduction
Salt is an important seasoning ingredient added
during cooking to increase the avour of dishes.
Also, salt is commonly added in processed foods as
a preservative, stabiliser, texture enhancer, colour
enhancer, and more. About 90% of salt is largely
added in food processing, in restaurant foods, in
sauces and cooking (Choong et al., 2012). Sauces
are liquid or semi-liquid seasonings that provide
avour, moisture and visual appeal to dishes. They
are rarely consumed by themselves, but served as an
accompaniment to food or an ingredient in cooking
foods (Codex Alimentarius, 1995).
Salt is high in sodium, which contains about
2000 mg or 88 mM sodium in one teaspoon (5 g) of
salt as declared by the Malaysian Dietary Guideline
(MDG) (NCCFN, 2010). Sauce is also known as one
of the foods that high in sodium. Since 1980, some
avouring agents, such as soy sauce, Worcestershire
sauce, catsup, pickles, olives, and garlic, onion,
and celery salts, were claimed to be high in sodium
(Marsh et al., 1980).
Salt is classied into organic and inorganic salts.
Organic salt is dened as salt that containing organic
ion. The name “organic salt” has been given for
commercial purpose. Organic salt is referring to all
salts obtained from natural sources, including table
salt. However, we categorized table salt as inorganic
salt because some of the table salts are synthesized by
the factory, especially in the form of sodium chloride.
Sodium is a naturally occurring mineral in most foods
with a small amount. It is necessary for humans to
maintain the balance of physical uid system and
is also required for nerve and muscle functioning.
However, too much sodium can damage human’s
kidneys and increase the chances of high blood
pressure (Munteanu and Iliuţã, 2011). In contrast,
an adequate intake of potassium can compensate the
adverse effects of sodium on blood pressure, lower
blood pressure and decrease the risk of hypertension
(Bussemaker et al., 2010).
The topics of excessive sodium and insufcient
potassium intake were being concerned in these few
years as both are leading to some adverse effects on
human health. In Malaysia, a recent Ministry of Health
survey reported the mean population salt intake had
achieved 8.7 g a day, which is equivalent to 3419 mg
Keywords
Atomic absorption
spectroscopy
Potassium
Preservative salts
Sauces
Sodium
Article history
Received: 27 August 2015
Received in revised form:
14 January 2016
Accepted: 29 January 2016
2182 Tan et al/IFRJ 23(5): 2181-2186
of sodium. The sodium intake of Malaysians is much
higher now, contributed up to 1.7 times, than the limit
set by the WHO (NCD-MOH, 2012). In contrast to
the current trend of excessive sodium intake, a study
in 2010 revealed that many countries do not meet the
daily recommended potassium intake. A study that
collected data from 21 countries spread across North
America, Europe, Asia and Oceania reported that the
average potassium intakes of these countries ranged
from 1.7 g (in China) to 3.7 g per day (in Finland, the
Netherlands and Poland) (Van Mierlo et al., 2010).
In Malaysia, sodium and potassium contents are
not included in the mandatory nutrition labelling
on packaged foods (Hawkes, 2004). Thus, there is
lack of sodium and potassium information labelled
on salts and sauces products that sold in Malaysia.
Besides, Market Watch (2012) reported the increased
in sales volume (2.98%) than the production volume
for sauces, dressing and condiments (2.84%) from
year 2009 to 2010. This shows the increasing trend
for sodium intake among Malaysian. In addition,
there is no publication in this country reporting on
the amount of sodium and potassium in imported
salts, such as Himalayan pink salt and bamboo salt.
Therefore, there is a need to determine and compare
sodium and potassium contents in selected salts and
sauces that available in Malaysia market.
Materials and Methods
Sample
A total of ten samples was selected to be analysed
in this study, included ve types of salts (rened table
salt, Himalayan pink salt, kosher salt, bamboo salt,
French sea salt) and ve types of sauces which can
directly add to foods (tomato ketchup, chili sauce,
mayonnaise, sweet soy sauce and light soy sauce).
A convenience sampling method was used to collect
these samples. The samples were purchased in two
supermarkets from Kuala Lumpur and Selangor,
Malaysia. The brand of each sample was randomly
selected from variety brands that available in the
markets.
Preparation of samples
There were three types of forms presented among
the samples, which were liquid form (light soy sauce),
viscous form (tomato sauce, chili sauce, mayonnaise
and sweet soy sauce) and solid form (rened table
salt, Himalayan pink salt, Kosher salt, bamboo salt,
French sea salt). The methods of preparation of
samples before ashing were different according to
their forms. The liquid sample was homogenised
by inverted the sample container for several times
to make sure that all components in the sample was
thoroughly mixed well. The preparation of plain
viscous samples was simple as well by mixed each
sample in a beaker with a spatula until homogeneous.
The solid samples were prepared by grinding the
sample with pastel and mortar into a ne powder.
After that, the ne powder was mixed well in order
to get a homogeneous sample.
Preparation of ash solution
There were some cleaning processes on the
apparatus needed to be carried out before started to
dry ash the samples. In order to prevent the presence
of minerals that capable to contaminate the samples
and affect the results, all the apparatus must be cleaned
thoroughly by rinsing 3-4 times using distilled water.
The dry ashing method was preceded by weighing
0.001 g (for determination of sodium) and 0.005 g
(for determination of potassium) of homogenised
sample in a crucible with an electronic balance. The
particular sample weights were required based on
the analytical working range and detection limits of
ame atomic absorption spectrometry (AAS) (Perkin
Elmer, 2011). Later, the crucible with sample was
placed on a hotplate in fume hood and heated until it
became charred. Sample must be dried before ashing.
Otherwise, bursting sound can be heard inside the
furnace during the ashing. Therefore, the sample
was allowed to dry in an oven at 130°C for one day.
After that, the sample was placed in a mufe furnace
at 550°C overnight. The completely ashed sample
should be free of black carbon particles and turned
into white or grey in colour (AOAC, 2000).
After ashing, the preparation of ash solution was
begun by adding 5 ml of concentrated HCl to the
ash and evaporated it to dryness on the steam bath.
Additional 2 ml of concentrated HCl was added to
dissolve the residue and support the mineralisation.
The crucible was swirled with care so that all ash
comes into contact with acid. Then, the crucible was
covered with a watch glass and heated on the hot plate
until the solution started to boil. The watch glass was
rinsed down with 20 ml of distilled water and the
solution was ltered using the Whatman No 41. lter
paper into a 100 ml of volumetric ask. At the same
time, the crucible and residue were also washed and
ltered with 10 ml of boiling water through the lter
into the same volumetric ask. The washing steps
were repeated for at least three times to ensure that
all the residues were ltered without leftover. At last,
the solution was cooled and made up to a volume of
100 ml with distilled water (AOAC, 2000).
Tan et al/IFRJ 23(5): 2181-2186 2183
Determination of sodium and potassium in salts and
sauces
The ash solutions were prepared for the
analysis of sodium and potassium contents in the
selected salts and sauces by ame AAS. Before the
measurements were started, the instrument was set
up according to the operating parameters (Table 1).
A series of potassium (0.0 to 1.5 ppm) or sodium
calibration solution (0.0 to 0.8 ppm) were prepared
from potassium standard solution or sodium standard
solution (1000 ppm) using dilution method. The
standard curves of absorbance versus concentration
of sodium or potassium were plotted by measuring
the absorbance of several calibration solutions with
known concentrations through ame AAS. The ideal
standard curve was stated by Beer-Lambert law that
the absorbance of an absorbing analyte is directly
proportional to its concentration for the existing set
of conditions. The equations of the standard curves
for sodium and potassium were y = 0.515x + 0.044
(R2 = 0.999) and y = 0.307x + 0.021 (R2 = 0.998),
respectively.
Statistical analysis
All data are presented as mean ± standard
deviation of three replicates. The statistical signicant
differences of the samples were analysed using SPSS
for Windows, version 21. The mean differences
among the samples were analysed using ANOVA with
post-hoc Tukey HSD test. The signicant difference
was set at p<0.05.
Results and Discussion
The sodium contents of various salts were almost
similar, which in the range of 31235.0-35870.0
mg/100 g. As shown in Table 2, the concentration of
sodium in these salts was in the order of table salt
(35870.0 mg/100 g), bamboo salt (35055.0 mg/100
g), Himalayan pink salt (34805.0 mg/100 g), kosher
salt (34610.0 mg/100 g) and French sea salt (31235.0
mg/100 g).
The present study found that there were no
signicant differences between the sodium amounts
(mg/100 g) in all the ve selected salts, included both
organic and inorganic salts. It has been declared that
there is usually little difference between table salt
and most sea salt on their sodium content that contain
about 40% sodium by weight (Brown, 2013). As
kosher salt and some sea salts may have larger crystal
sizes than the table salt, which results in these salts
have less sodium by volume, such as by teaspoon or
tablespoon, but not by weight (Marcus, 2013). The
amount of sodium in studied table salt was slightly
lower than salt in USDA database (38758 mg/100 g)
(United State Department of Agriculture [USDA],
2016).
Based on Table 2, it was clearly showed that the
potassium content in salts was considered small as
compared to sodium content. The potassium content
of different salts was in the order of bamboo salt
(399.4 mg/100 g), French sea salt (284.3 mg/100 g),
Himalayan pink salt (246.6 mg/100 g), Kosher salt
(182.7 mg/100 g) and table salt (43.7 mg/100 g).
The potassium level of table salt was found to be
signicantly lower than other types of the selected
salts, which were French sea salt, bamboo salt
and Himalayan pink salt. However, no signicant
difference was found between table salt and kosher
salt in terms of potassium content. The results obtained
from this nding were similar to the data provided
by the manufacturer. Usually all minerals, other than
sodium, were stripped from table salt during the
rening process which reasonably explain why this
salt contains little amount of potassium compared to
others (Zeratsky, 2010). Potassium content of studied
table salt was 8 times higher than the reported value
in USDA Nutrient database (USDA, 2016).
Table 1. Operating parameters for ame AAS
Table 2. Sodium and potassium contents of selected salts
Different superscript lowercase letters (a– c) denote signicant difference between the samples
2184 Tan et al/IFRJ 23(5): 2181-2186
Meanwhile, the present study also found that
bamboo salt contained a signicantly higher amount
of potassium compared to Kosher salt and Himalayan
pink salt. The special manufacturing method of
bamboo salt is the key reason in its high potassium
content. Bamboo was known to be high in minerals,
such as calcium, phosphorus and potassium (Bhatt et
al., 2005). The steps of stufng salt inside bamboo
and baked them brought the nutrients of bamboo fully
integrated into the salt (Kim et al., 2012). However,
the source of potassium in other salts was completely
related to the place of origin without any additional
supply. Therefore, compared to other salts, the
potassium contained in bamboo salt was signicantly
higher.
The sodium content of varieties sauces is shown
in Table 3. In contrast to salts, the range of sodium
in the selected sauces was broad, which was in range
from 231.3 to 4402.0 mg/100 g. Light soy sauce
contained the highest amount of sodium (4402.0
mg/100 g), followed by sweet soy sauce (3106.0
mg/100 g), tomato ketchup (703.5 mg/100 g), chili
sauce (553.1 mg/100 g) and mayonnaise (231.3
mg/100 g). Generally, the sodium content of soy
sauce in the study was lower than the reported values
of soy sauce varieties (exception for low sodium
and reduced sodium) of USDA database (5493-
6820 mg/100g). While ordinary catsup was reported
to contain lower sodium of 907 mg/100g (USDA,
2016).
The amounts of sodium found in light soy sauce
and sweet soy sauce were signicantly higher than
the other selected sauces. However, no signicant
difference in sodium content was found between
these two sauces. Soy sauce is commonly known as
a high sodium sauce. In 2013, researches in Colorado
State University classied the food items according
to sodium content and gave out the same result as in
the present study. The study grouped tomato ketchup
and mayonnaise into food item with elevated sodium
while soy sauce in the group of high sodium (Bellows
and Moore, 2013).
The higher sodium content of light soy sauce and
sweet soy sauce compared to other studied samples
was coming from the addition of salt during the
manufacturing process. A large amount of salt was
required in suppressing putrefactive bacteria and
other destructive organisms, to leave the valuable
microorganisms, koji mold, lactic acid bacteria,
and yeast, free to work (Thaker and Barton, 2012).
Besides that, salt as a main raw material was
important in providing the base of the salty taste
and contributing to the unique appearance, colour,
avour and fragrance of soy sauce. However, in
the production of chili sauce, tomato ketchup and
mayonnaise, salt was just a secondary ingredient and
its effect was less important besides just giving the
taste. There was only 2 to 3% of tomato ketchup and
chili sauce, and 1.5% of mayonnaise constituted by
salt (Hui, 2006; Brown, 2013). Therefore, sodium
levels in these three sauces were not as high as light
soy sauce and sweet soy sauce.
According to Table 3, light soy sauce had the
highest level of potassium (395.4 mg/100 g) among
all the selected sauces whereas mayonnaise contained
the lowest (63.6 mg/100 g). At the same time, the
amount of potassium found in sweet soy sauce,
tomato ketchup and chili sauce were 308.8, 289.5 and
200.0 ± 31.9 mg/100 g respectively. When compared
to USDA database, the level of potassium in soy
sauce varieties was generally in a broader range of
212 to 3098 mg/100 g especially in the soy sauce
from hydrolysed vegetable protein with reduced
sodium. While regular mayonnaise in the database
was reported to contain only 20mg/100 of potassium
(USDA, 2016).
From Table 3, it is clear that potassium content
of mayonnaise was signicantly less than the other
sauces. There was an obvious difference between
the principle ingredients of mayonnaise and other
sauces. Mayonnaise was mainly made from egg yolk,
vegetable oil and vinegar whereas the other sauces
were containing soybean, chili and tomato (Hui,
2006; Shurtleff and Aoyagi, 2012; Brown, 2013).
Generally, potassium is largely obtained in fruits,
vegetables, nuts and whole grains.
Apart from that, potassium level in light soy
sauce was signicantly higher than chili sauce. The
amount of potassium was largely affected by the main
ingredients used in processing the sauce. Light soy
Table 3. Sodium and potassium contents of selected sauces
Different superscript lowercase letters (a– c) denote signicant difference between the samples.
Tan et al/IFRJ 23(5): 2181-2186 2185
sauce is produced from soybean while peeled tomato
is the basic ingredient of chili sauce. According to
USDA Nutrient Database, the potassium content
of soybean is higher than that in tomato (U.S.
Department of Agriculture, 2014). Besides that, the
tomato peeling process during manufacturing of
chili sauce further reduces its potassium content.
Based on Elbadrawy and Sello (2011), tomato peel
contains high level of potassium. At the same time,
another study by Navarro-González et al. (2011) also
reported that potassium is one of the major elements
in tomato peel. Thus, there was no doubt that light
soy sauce contained signicantly higher potassium
content than chili sauce. Sweet soy sauce was also
mainly produced from soybean; however, the process
of adding caramel and re-fermentation caused the
potassium level became less cumulated (Hui et al.,
2003). Therefore, no signicant difference was found
between the potassium content of sweet soy sauce
and chilli sauce.
Conclusions
Sodium contents of the selected salts were not
signicantly different. In contrast, potassium content
was signicantly higher in organic salt, especially
the bamboo salt. Therefore, organic salt is a better
choice of salt for consumers instead of table salt
related to potassium content. Yet, the consumers are
encouraged to control their daily sodium intake in
order to maintain health, particularly for hypertensive
patients. As expected, light soy sauce and sweet soy
sauce were signicantly higher in sodium content
than other sauces. At the same time, light soy sauce
contained the highest amount of potassium. Although
its potassium content was relatively higher compared
to others, it may not compensate the potential risk
of adverse health outcomes resulting from its high
sodium content.
Health problem related to excessive sodium
intake is a high concerned in many countries
nowadays. Therefore, the consumers are encouraged
to reduce the intake of sauces with higher sodium
content, such as soy sauce. Further exploration about
the nutritional contents of salts and sauces is required
in order to provide consumers an opportunity to know
the nutritional value of salts and sauces, followed by
making the proper decision in choosing and using
these salts and sauces.
Acknowledgement
The authors would like to thanks all staffs from
nutrition laboratory in UPM for helping in this study.
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