Preliminary Comparative Sodium Analysis of Different Tempeh Types in Indonesia and Its Benefits for Hemodialysis

Fery Lusviana Widiany ^1,* , Metty ², Rahayu Widaryanti ³, Shafira Nur Azizah ²

1. Dietetic Internship Education Study Program, Faculty of Health Science, Universitas Respati Yogyakarta, Yogyakarta, Indonesia

2. Bachelor of Nutrition Study Program, Faculty of Health Science, Universitas Respati Yogyakarta, Yogyakarta, Indonesia

3. Bachelor of Midwifery Study Program, Universitas Respati Yogyakarta, Yogyakarta, Indonesia

* Correspondence: Fery Lusviana Widiany 

Academic Editor: Charles Odilichukwu R. Okpala

Special Issue: Eating Disorder and Health

Received: April 01, 2025 | Accepted: September 15, 2025 | Published: September 19, 2025

Recent Progress in Nutrition 2025, Volume 5, Issue 3, doi:10.21926/rpn.2503020

Recommended citation: Widiany FL, Metty, Widaryanti R, Azizah SN. Preliminary Comparative Sodium Analysis of Different Tempeh Types in Indonesia and Its Benefits for Hemodialysis. Recent Progress in Nutrition 2025; 5(3): 020; doi:10.21926/rpn.2503020.

© 2025 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.

1. Introduction

Chronic kidney disease is a degenerative condition with a high incidence rate. Basic Health Research Data in Indonesia in 2018 showed a prevalence of 0.38%, an increase from 2013, which was only 0.2% [1,2]. Patients with end-stage chronic kidney disease need to undergo routine long-term hemodialysis, which is the most common treatment requiring some dietary restrictions [3]. The primary role of routine hemodialysis is to balance the extracellular fluid volume, which is achieved by a neutral sodium balance between sodium intake between dialysis sessions and sodium excretion during the first hemodialysis session. However, current hemodialysis still uses high sodium bicarbonate dialysis to reduce dialysis-induced hypotension, which is not physiological and causes an increase in extracellular fluid volume and hypertension [4]. In an effort to reduce blood sodium content and prevent hypertension in hemodialysis patients, it is necessary to regulate their diet by limiting sodium intake from oral intake. However, hemodialysis patients still require a high-protein diet to replace the large amounts of amino acids lost through the hemodialysis process.

One of the local Indonesian foods that is a familiar traditional source of protein is tempeh, which is made from beans, including soybeans. However, the available soybeans in Indonesia consist of several varieties, both local and imported. Imported soybean tempeh is often found and sold at cheap prices in traditional markets. In contrast, local soybean tempeh is less standard in conventional markets, and the price is relatively more expensive than imported soybean tempeh. Accordingly, people prefer to consume imported soybean tempeh compared to local soybean tempeh. Local soybean tempeh is thought to have better nutritional content than imported soybean tempeh, including its use for hemodialysis patients.

One of the local soybean varieties that is widely used to make tempeh is the Grobogan soybean type. Tempeh has high protein content, high fiber, high isoflavones, and low fat. The nutrients contained in tempeh are more easily digested, absorbed, and utilized by the body compared to those in soybeans. Tempeh from Grobogan soybeans has the same texture as tempeh from imported soybeans. However, imported soybeans have a lower protein content than local soybeans [5]. Indonesian local soybean tempeh has a higher content of almost all amino acids compared to imported soybean tempeh. However, both types of tempeh have methionine as a limiting amino acid with a relatively low content [6,7]. This fact proves that, from the aspect of protein content, local Indonesian soybean tempeh of the Grobogan variety is better consumed by hemodialysis patients than imported soybean tempeh [6]. More detailed research regarding the differences in sodium content of the two types of tempeh also needs to be analyzed, considering that hemodialysis patients require limiting sodium from their food and drinks due to the concerns about electrolyte imbalance and dialysis-induced hyper-/hypotension. This research was conducted to compare the sodium analysis of different tempeh types in Indonesia as a preliminary study for the subsequent research to fulfill a high-protein, low-sodium food for hemodialysis patients.

2. Materials and Methods

2.1 Ethics Statement

This research was conducted after obtaining ethical clearance (Number: 116.3/FIKES/PL/VII/2022) from the Health Research Ethics Committee of Universitas Respati Yogyakarta.

2.2 Type of Research

This was an actual experimental research study, conducted in 2022 at Universitas Respati Yogyakarta and the Analytical Chemistry Laboratory (ACL) of the Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada (UGM), Indonesia. The variable studied was sodium content. The sodium content was identified in local Indonesian soybean tempeh flour of the Grobogan variety and imported soybean tempeh flour.

2.3 Data Collection

The Grobogan soybean tempeh analyzed in this study was obtained from a Grobogan soybean tempeh producer with the Attempe brand. In contrast, the imported soybean tempeh was obtained from an imported soybean tempeh producer with the Super Dangsul brand. The tempeh was purchased at the beginning of the study in June 2022. The experiment was repeated twice and analyzed in triplicate in the ACL-UGM. The number of samples required for analysis was 50 grams.

The tempeh flouring process was done at the Dietetics and Culinary Laboratory at Universitas Respati Yogyakarta. The tempeh flouring procedure in this study refers to previous research conducted by the researchers [8]. Whole tempeh was cut into small pieces measuring 2 cm × 0.5 cm × 0.5 cm, then steamed for 15 minutes to inactivate the enzyme. The steaming process was intended to stop the fermentation process. The steamed tempeh was then dried at a temperature of 50°C for ±10 hours, using a drying cabinet (Type-IL-70, AM1108/39E, T.E.W. Electric Heating Equipment Co., Taiwan). When dried, the tempeh was turned every 2 hours so that it dries evenly. Once dry, the tempeh was then mashed using a blender and filtered using a 60-mesh flour sieve.

The tempeh flour was then taken to the ACL-UGM to be analyzed for sodium content. Analysis of sodium content used the Atomic Absorption Spectrophotometry (AAS) method. The AAS method was conducted in the Inorganic Chemistry Laboratory of the Faculty of Mathematics and Natural Sciences, UGM, using an AAS (Perkin Elmer Series 300, USA). This AAS method plays a vital role in the identification and quantification of metallic elements present in a given sample, and is an essential analytical technique used in various industries [9]. The analysis results were displayed on a ratio scale with ppm units, which were then converted to mg/100 g units.

2.4 Statistical Analysis

Sodium content data were analyzed univariately and bivariately to see the difference in sodium content between Grobogan variety soybean tempeh and imported soybean tempeh. The data normality test using the Shapiro-Wilk test showed a result of p > 0.05 (normally distributed data), so bivariate analysis was done with the independent T-test using the SPSS-23 program (IBM Corp., Chicago).

3. Results

Analysis of sodium content in this study was conducted on samples of local Indonesian soybean tempeh of the Grobogan variety and imported soybean tempeh flour in flour form.

Table 1 shows that there was a significant difference in sodium content between local Indonesian soybean tempeh of the Grobogan variety and imported soybean tempeh, indicated by a value of p = 0.001 (p < 0.05). The sodium content of local Indonesian soybean tempeh of the Grobogan variety was significantly lower than that of imported soybean tempeh.

Table 1 Differences in Micronutrient Content of Local Soy Tempe and Imported Soy Tempe.

Based on the results of the analysis, it is known that the mean difference value was -1.00293. This value showed that the average sodium content of Grobogan soybean tempeh flour is 1 mg/100 g lower when compared to the average sodium content of imported soybean tempeh flour. The average sodium content of Grobogan soybean tempeh flour was 19.5 mg/100 g, which was significantly lower than the average sodium content of imported soybean tempeh flour (20.5 mg/100 g).

4. Discussion

Tempeh is a nutritious fermented legume food made from soybeans and commonly consumed in Indonesia. Indonesians have long relied on tempeh as a daily and affordable source of protein. Tempeh contains not only nutrients but also several bioactive compounds, including isoflavones. The fermentation process involves the growth of Rhizopus spp. Fungi, which produce enzymes that break down the complex nutrients in soybeans into simpler forms, making this protein- and nutrient-rich food more easily absorbed by the body. Soybean fermentation also produces metabolites such as organic acids, antioxidants, and antimicrobial compounds that increase the vitamin content, improve nutritional value, and extend the shelf life of tempeh. Tempeh consumption has been linked to various health benefits, including antidiabetic effects, cholesterol-lowering properties, enhanced cognitive function, antitumor and anticancer properties, anti-aging effects, and improved gut health and a reduced risk of cardiovascular disease [10,11,12].

This research examines and compares the sodium content between local Indonesian soybean tempeh of the Grobogan variety and imported soybean tempeh. Imported soybean tempeh is easy to find in traditional markets and can be purchased at a relatively cheaper price than local soybean tempeh. The local soybean tempeh of the Grobogan variety in this study had a higher amino acid content and IC50 antioxidant activity than imported soybean tempeh [6,13]. Accordingly, it turns out that local soybean tempeh is considered more beneficial, especially for hemodialysis patients, due to its lower sodium content.

Hemodialysis patients are at increased risk of sodium retention because the kidneys are unable to excrete sodium. Sodium is the primary solute in the extracellular compartment and a significant component of serum osmolality. In healthy individuals, sodium homeostasis is maintained through a balance between dietary sodium intake and urinary sodium excretion. In contrast, in hemodialysis patients, sodium balance depends on food intake and sodium excretion during hemodialysis [4].

Sodium intake from food consumed by hemodialysis patients is positively correlated with water intake, likely due to increased thirst. High sodium content is associated with interdialytic weight gain (IDWG), increased blood pressure, and increased extracellular fluid volume, which is reported to be the leading risk factor for premature death in hemodialysis patients [14,15,16]. Patients undergoing regular hemodialysis are strongly advised to follow a low-sodium diet. This dietary restriction aims to reduce IDWGs and ultrafiltration requirements, prevent hypertension, and avoid potential future heart problems [17,18].

The nutritional needs of hemodialysis patients are 30–35 kcal/kg ideal body weight per day for energy, 1.2 g/kg ideal body weight per day for protein, 80–100 mmol/day for sodium, <1 mmol/kg ideal body weight/day for potassium, and 800–1000 mg/day for phosphorus. Protein sources should comprise 50% high-biological-value proteins that contain essential amino acids [19]. A sodium-restricted diet is highly recommended for hemodialysis patients. However, patients do not always comply with this dietary recommendation [17,18]. The results of research in New Zealand reported that the average sodium intake was 2502 mg/day, and more than half of the respondents consumed more sodium than the recommended requirement [20]. Additionally, sodium consumption can improve nutritional status by increasing the patient's appetite. Foods with sufficient sodium content can provide a salty or savory taste, thereby increasing the patient's appetite. Low salt intake is associated with high rates of all-cause mortality in hemodialysis patients. This increased mortality risk is caused by malnutrition due to excessive salt restriction [16,21,22]. Protein energy catabolism is prevalent in hemodialysis patients due to poor appetite, inflammation, and malnutrition resulting from the hemodialysis process [23]. Hemodialysis patients must consume sufficient energy and protein according to dietary recommendations to avoid protein-energy deficits and malnutrition [24]. Accordingly, in limiting sodium, it is essential to maintain a balance of the negative and positive effects of sodium intake in hemodialysis patients [16].

One of the factors that influences patient compliance in implementing a diet program is their nutritional knowledge [25]. The study's results showed that patients undergoing hemodialysis had less knowledge about the sodium content in food, and more than half were unaware of the risk of non-adherence to high sodium intake, including the potential for death from cardiovascular disease. Patients may be more likely to reduce sodium intake if they know the recommended sodium content [26,27].

Sodium is not only contained in table salt, but also in other foods consumed daily by hemodialysis patients. However, there are food ingredients that are recommended for consumption by hemodialysis patients because they have low sodium content, one of which is tempeh [28]. The results of this study confirmed that the average sodium content of Grobogan soybean tempeh flour was 19.5 mg/100 g, significantly lower than the average sodium content of imported soybean tempeh flour. Thus, local soybean tempeh can be used as an alternative source of protein that hemodialysis patients with sodium restrictions can consume. The main finding of this study clearly indicated that the sodium content in Grobogan soybean tempeh is lower than that of imported soybean tempeh, which can be caused by local Indonesian soybean tempeh being made from fresher/newer soybeans because they have just been harvested. Generally, it is also higher in nutrition, organoleptic, and reasonably priced. Meanwhile, the imported soybeans could have been harvested a year earlier, which could have negatively affected their freshness and nutritional content. In addition, imported soybeans are also likely to be transgenic soybeans (gene-engineered) whose protein content is lower than that of local soybeans [29].

The finding that Grobogan soybean tempeh contains lower sodium levels may not be enough to conclude that this soybean tempeh is superior to imported soybean tempeh. If the sodium levels in both types of soybean tempeh exceed the maximum recommended intake, the comparison becomes less meaningful. Therefore, dietary management in hemodialysis patients still requires calculating the amount of protein requirements that can be met from other food sources, including Grobogan soybean tempeh. However, hemodialysis patients must consume sodium sourced not only from table salt, namely 1000–1500 mg/day [30], while maintaining vigilance over other sodium sources in their diet to meet these daily requirements. Local soybean tempeh can be consumed three times a day at main meal times, with portion sizes according to each patient's needs. Grobogan soybean tempeh can be used as an alternative food source of low-sodium protein for hemodialysis patients. Still, it also requires regulating consumption according to daily protein needs to avoid excessive sodium intake in hemodialysis patients.

5. Conclusions

The sodium content of Grobogan soybean tempeh flour was 19.5 mg/100 g, significantly lower than the average sodium content of imported soybean tempeh flour, so local soybean tempeh is considered more beneficial for hemodialysis patients than imported soybean tempeh. Local soybean tempeh from the Grobogan variety can be used as an alternative food source of low-sodium protein for hemodialysis patients. However, due to concerns about electrolyte imbalance and dialysis-induced hyper-/hypotension, dietitians still need to regulate and monitor overall dietary consumption according to daily protein requirements to avoid excessive sodium intake in hemodialysis patients.

Acknowledgments

Acknowledgement is conveyed to Universitas Respati Yogyakarta, which has funded this research through internal grants, so that this research can be accomplished well. Many thanks are also conveyed to Mr. Erik Christopher Hookom B.A., M.Ed., TEFL as the Senior Consultant of Academic Writing and English Literacy from Universitas Gadjah Mada, Indonesia, for proofreading the manuscript.

Author Contributions

Dr. Fery Lusviana Widiany was responsible for project development and the main contributor in the writing process of the manuscript, Ms. Metty conducted data collection, Ms. Rahayu Widaryanti performed statistical analysis, and Ms. Shafira Nur Azizah wrote the research results. All authors read and approved the final manuscript.

Funding

Support funding from Universitas Respati Yogyakarta, in the Program of "Hibah Penelitian Internal", Project No. 01/Pen/Hibah.Int/PPPM/VI/2022.

Competing Interests

The authors have declared that no competing interests exist.