Asian Journal of Dietetics, 2024

Original
Replacement of Sea Salt with Aizuyamajio may Reduce Salt Consumption in Japan
Shin Yamaoka1, *1

Department of Food and Nutrition, Junior College Division, University of Aizu, Fukushima Japan
ABSTRACT Background and purpose. Excessive salt intake is a global health concern. In the
Aizu region of Fukushima Prefecture in Japan, Aizuyamajio is made from hot spring water andhas a lower salt content than sea salt. In this study conducted a sensory evaluation of
Aizuyamajio and sea salt, and compared the differences. Methods. Fourteen students fromdifferent prefectures consented to participate in this study. For the sensory evaluation method,
participants rated sea salt and Aizuyamajio on their sweetness, saltiness, bitterness, sourness,and umami which were further evaluated using the four-point method. Additionally,
respondents freely answered questions regarding the use of Aizuyamajio for cooking. Results.
On comparing the sweet, salty, bitter, sour, and umami tastes between Aizuyamajio and sea
salt, a significant difference was noted in the saltiness, however, no other significant
differences were observed. Thirty-five methods have been suggested for using Aizuyamajio
for cooking. Conclusion. The results of this study suggest that sea salt and Aizuyamajio havedifferent tastes and lower salt equivalents. Furthermore, Aizuyamajio has a different taste fromsea salt and may be used as a low-salt seasoning.
Keywords: Aizuyamajio, sea salt, low-salt, salty, tastes

INTRODUCTION
Excessive salt intake is associated with lifestylerelated diseases, such as hypertension (1).
Hypertension, in turn, is associated withcerebrovascular diseases including arteriosclerosis(1). World Health Organization (2) recommends a
sodium intake of less than 2000 mg/day (equivalent toless than 5 g/day of salt) for adults to maintain good
health. However, the global average sodium intake for
adults is reported to be 4310 mg/day (equivalent to10.78 g/day of salt) (3).
In Japan, Dietary Reference Intakes for Japanese(2020) has set the daily salt intake for men and women(for those 18 years of age or older) at less than 7.5 g
and less than 6.5 g, respectively (4). However,according to the 2019 Japanese National Health andNutrition Survey, the average salt intake was 10.1g
and 9.3 g for men and women, respectively (5). Hence,
efforts to reduce salt consumption are required, which
may serve as a role model and contribute significantly
to improving health worldwide.
When the body ingests excessive amounts of salt,
it increases the salt concentration in the plasma
volume, resulting in an increase in water content in the
blood and a subsequent increase in plasma volume (6).
As a result, contribute to the cause of hypertension
develops when the pressure on the plasma volume
vessels increases to circulate more plasma (6).
In Japan, sea salt is commonly consumed and ismainly prepared from seawater. There is salt madefrom hot spring water in the Aizu region of Fukushima
Prefecture (7). That salt termed Aizuyamajio (7). The
Aizuyamajio content in hot spring water in the Aizu
region is 16.5 g/L, lower than the 23 g/L of seawater,
the source of sea salt (7). The nutritional value of sea
salt (A co. anonymised for commercial purposes) per
100 g is 0 kcal of energy, 0 g of protein, 0 g of fat, 0 gof carbohydrates, 95.0 g of salt equivalent, 350
mg of potassium, 200 mg of calcium, and 570 mg ofmagnesium. The nutritional value of Aizuyamajio per
100 g is 0 kcal of energy, 0 g of protein, 0 g of fat, 0 gof carbohydrates, 77.8 g of salt equivalent, 400 mg ofpotassium, 2200 mg of calcium, and 400 mg ofmagnesium. Therefore, Aizuyamajio has less saltcontent compared to sea salt of the same amount.
Using Aizuyamajio instead of sea salt as a seasoning
may help reduce excessive salt intake. However, very
few studies have between Aizuyamajio and sea salt
and their preparation methods. In this study conducteda sensory evaluation of Aizuyamajio and sea salt,
compared differences in taste, and examined cooking
methods using Aizuyamajio to improve the use of
Aizuyamajio in cooking.
MATERIALS AND METHODS
Participants and methods
All study participants provided informed consent,
and this study was approved by the University of Aizu
Research Ethics Committee (2023 University of Aizu
Plan No. 77). In this study verbally explained to theparticipants that their privacy would be protected andthat there would be no disadvantages based on whether
they responded. Also, participants were given an
explanation of the study design and aim of theexperiment. Those subject to ethical considerations
were informed and consented to participate by signinga consent form. A prepaid card worth 1,500 JPY(approximately $9.9) was provided to the respondents
after survey completion as compensation for theirtime. Those who were unwell were excluded from thestudy participant. This study was conducted on 14
students from A junior college in A prefecture who
consented to be the research participants of this study.
The study was performed in only one day. Study
participants conducted a sensory evaluation of
Aizuyamajio and cooking methods by eating
Aizuyamajio.
The sensory evaluation method was as follows.
First, 1 cup (approximately 0.1 g) of sea salt (A co.

*To whom correspondence should be addressed:
s_yama@jc.u-aizu.ac.jp

21

Aizuyamajio may reduce salt consumption
anonymised for commercial purposes) was placed ona cocktail steer (Muddler Spoon Ivory 100 Pieces
Artnap). Participants drank one glass of water to get
rid of the sea salt left in them mouth. Subsequently,
they consumed one cup (approximately 0.1 g) of
Aizuyamajio (Purchased from: AizuYamajio Kigyo
Kumiai, All Rights Reserved Aizu Yamajio Kigyo
Kumiai) different from the one that they had
consumed earlier. Then filled out a self-administeredquestionnaire (Questionnaire) about the five tastes ofsweetness, saltiness, bitterness, sourness, and umami
as well as how to use Aizuyamajio. The study design

is shown in Fig 1. The sweet, salty, bitter, sour, andumami tastes of Aizuyamajio and sea salts were
evaluated using the four-point scale, and theappropriate answers were marked with a circle.
Statistical analyses
The Student's t-test was performed on the results
using Excel statistical software to compare
Aizuyamajio and sea salt. In all cases, a p-value of<0.05 was considered statistically significant.
Additionally, respondents were free to answer
questions regarding the use of Aizuyamajio for
cooking.

Fig 1. Study design
Questionnaire: Sex
AgePlease circle the one you think is most appropriate for each category of sea salt and Aizuyamajio.
Sea salt
Aizuyamajio
Sweetness
Sweet・Somewhat sweet ・Sweet・Somewhat sweet ・Somewhat not sweet・Not sweet
Somewhat not sweet・Not sweet
Salty
Salty・Somewhat salty・Salty・Somewhat salty・
Somewhat not salty・Not salty
Somewhat not salty・Not salty
BitterBitter・Somewhat bitter・Bitter・Somewhat bitter・taste
Somewhat not bitter・Not bitter
Somewhat not bitter・Not bitter
Acidity
Sour・Somewhat sour・
Sour・Somewhat sour・Somewhat not sour・Not sour
Somewhat not sour・Not sourUmami
Has umami・Somewhat umami・Has umami・Somewhat umami・Somewhat no umami・No umami
Somewhat no umami・No umami*If you use Aizuyamajio, please describe what kind of dishes you would use it for.
RESULTSAll the 14 participants were females aged
19.07±1.64 years (mean±SD). The results ofcomparing Aizuyamajio and sea salt in sweetness,saltiness, bitterness, sourness, and umami arepresented in Table 1. A significant difference wasobserved in the ‘saltiness’ of the taste, however, noother significant differences were noted.
Thirty-five methods have been proposed for theuse of Aizuyamajio in cooking which are listed inTable 2. As a result, dishes that are used with sea salt
in Japan were proposed.

Table 1 Comparison of the taste of sea salt and Aizuyamajio (same respondents, n=14)＊
There is a significant difference between sea salt and Aizuyamajio (p<0.05).

Sweetness
Salty
Bittertaste
Acidity
Umami

Sweet
0
Salty
9
Bitter
0
Sour
1
Has
umami
1

Sea salt
Number of respondents n=14
Somewhat
Somewhat not
sweet
sweet
4
2
Somewhat
Somewhat not
salty
salty
5
0
Somewhat
Somewhat not
bitterbitter4
0
Somewhat
Somewhat Not
sour
sour
5
1
Somewhat
Somewhat no
umami
umami
9
0

p-value
Not
Sweet
sweet
8
0.15
2
Not
Salty
salty
0
<0.01＊ 1
Not
Bitterbitter
10
0.15
3
Not
Sour
sour
7
0.24
0
No
Has
umami
umami
4
0.18
4

Table 2 Suggestion on how to cook Aizuyamajio

22

Aizuyamajio
Number of respondents n=14
Somewhat
Somewhat not
sweet
sweet
4
4
Somewhat
Somewhat not
salty
salty
9
2
Somewhat
Somewhat not
bitterbitter3
2
Somewhat Somewhat Not
sour
sour
3
1
Somewhat
Somewhat no
umami
umami
7
2

Not
sweet
4
Not
salty
2
Not
bitter
6
Not
sour
10
No
umami
1

Asian Journal of Dietetics, 2024

Suggested dishes
Ramen
Salt rice ballNigiri meshi
Salt soft serve ice cream
Sweets (Ice cream, etc.)
Ice cream
Salted chocolate pie
Daifuku (Japanese sweets)
Clear soup
Soup
Miso soup
Put on tempura
Sprinkle over tempura
TempuraSprinkle on grilled foods (such as shiitake mushrooms)
Grilled fish
Fish (cooked with plenty of salt)
Salt-grilled fish
Yakitori salty
SashimiFried vegetables
Cucumber
PicklesAjilloBoiledBoiled dishes
Japanese food
Chinese cuisine
The true taste of Aizuyamajio
Put on meat
Tamagoyaki
Egg dishes
Unless the answers were identical, they were written exactly as they were.
DISCUSSION AND CONCLUSION
In this study observed that the salty taste wasperceived to be significantly different among thesurvey participants at Junior College A in Prefecture
A on sensory evaluation of Aizuyamajio and sea salt,
and usage of Aizuyamajio in cooking. Additionally,
many foods that use sea salt are listed and can besubstituted with Aizuyamajio for cooking purposes.
The difference in the amount of salt equivalents is
considered to be the main reason for the differencein saltiness. The salt equivalent amount of
Aizuyamajio used in this study was 77.8 g per 100 g,
while that of sea salt was 95.0 g per 100 g. As aresult, the ratio of salt equivalent to Aizuyamajio/sea
salt was 18% lower at 77.8/95.0; therefore, many
participants felt that Aizuyamajio was saltier,whereas others felt that Aizuyamajio was less saltierthan sea salt.
For example, in a previous study, sensory tests
showed that healthy tasters, who were young
Japanese women in their late teens and 20s, wereunable to distinguish between salty tastes (sodium
chloride concentrations of 0.3%, 1.25%, 5%, 10%,and 20%). Therefore, a difference in the salt
equivalent amounting to 18% in this study wasrecognized (8). These results suggest that on
consuming an identical amount of Aizuyamajio as
sea salt, one may find it less salty.

Number of responses
3
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

Based on the results of the sensory evaluations
other than salty taste, there were no significant
differences; however, the results for sweetness,
bitterness, sourness, and umami, and taste perception
differed. This is attributed to the fact that the amountof mineral components is generally different in
Aizuyamajio than in sea salt. For example, studies
involving mineral water revealed that taste
sensations differed depending on the mineral (9).
Therefore, although there was no significant
difference between the Aizuyamajio and sea salt, theresults were not the same.
Many dishes that use sea salt as a seasoning or
dishes that are already made using Aizuyamajio havebeen cited (10,11). Regarding cooking methods for
Aizuyamajio, most of the foods mentioned include
those that use sea salt as a seasoning in Japan or thosethat are already prepared using Aizuyamajio. For
example, sea salt is used in Japanese food culture(12,13). Furthermore, sea salt is used in products
including ice cream. Aizuyamajio is used in cheese,rice balls, and ice cream, and has already beencommercialised. Similar foods were proposed in thisstudy, suggesting the possibility of using
Aizuyamajio in foods that already use sea salt.
The limitation of this study is that, although
Aizuyamajio use is popular in one region of Japan, it
is unclear whether they are widespread throughout

23

Aizuyamajio may reduce salt consumption
Japan. Additionally, the number of participants was
small and the results were limited to one area. If salt
is reduced by using Aizuyamajio, there is no known
data regarding its effect on the blood pressure ofindividuals, creating a need for further investigationof the effects of intake of Aizuyamajio.
In Japan, efforts are being made to reduce saltcontent by adding glutamic acid, monosodium
glutamate, calcium diglutamate, inosinic acid, andguanylic acid to umami substances which has beencommercialised (14). The equivalent amount of saltin Aizuyamajio is low, and it is thought that wild saltwith a different flavour may be added to the low-saltseasonings used in Japan and used as low-salt foods.
However, though Aizuyamajio consumption ispractised, is not with the intent of salt reduction.
Patients with mild essential hypertension had lower
blood pressure when they changed their diet from sea
salt to mineral-rich salt (15). Therefore, Aizuyamajio
may have the potential to improve hypertension.
Furthermore, Aizuyamajio may also be possible touse it as a low-salt food with a different taste thansea salt.
In conclusion, the results of this study revealed
that Aizuyamajio can be used as a low-salt food witha different taste from sea salt.

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AizuYamajio
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ACKNOWLEDGMENTS
Author would like to thank the research
participants. This study was supported by an internal
competitive research funding from the University of
Aizu. The author declared no conflicts of interest.
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