Shirataki, a Healthy Food Alternative with Lots of Fibre 

By: Rina Maulidiyah, Halal Auditor 

Shirataki, a food made from konjac tubers is now increasingly popular among healthy culinary lovers. With low-calorie content and high fibre, shirataki is an ideal choice for people who want to maintain a balanced diet without sacrificing taste. This food is also relatively easy and quick to process. What about the halal aspect? Does Shirataki need to be certified halal by the Halal Product Assurance Agency (BPJPH) through the Halal Inspection Body (LPH) LPPOM? 

The uniqueness of shirataki lies in its chewy texture and its ability to absorb the flavours of spices. This makes it an attractive alternative that can be processed easily and quickly into various dishes, from noodles to salads. Along with the increasing demand for shirataki, questions have arisen regarding its halalness and safety. 

Shirataki is a food made from konjac glucomannan, which comes from konjac tubers (Amorphophallus konjac)^[1]. Konjac glucomannan is a dietary fibre consisting of D-glucose and D-mannose units connected by β-1,4 glycosidic bonds with a few acetyl groups. 

This compound is easily soluble in water, can be fermented, and has high viscosity. Konjac glucomannan is a non-calorie food and a source of indigestible dietary fibre. It is also resistant to hydrolysis by digestive enzymes in the human digestive tract ^[2]. Shirataki has a clear colour, chewy texture and bland taste. Made from konjac glucomannan, shirataki is included as a low-calorie, high-fibre food ^[3]. 

HISTORY OF SHIRATAKI 

Shirataki is a traditional Japanese food known by another name, Ito-konyaku. Generally, shirataki is in the form of noodles or rice ^[4]. The name konnyaku first appeared in Japanese historical literature during the Heian Period. The Japanese consumed these noodles as a treatment for constipation in the Edo period and by monks in temples during the Kamakura period. 

During the Edo era, a processing technique known as “konnyaku crushing” was discovered, which made it easier for people to process konjac tubers without having to handle them directly. In addition, the technique extended their shelf life. Shirataki was widely produced in Japan’s Kanto and Kansai regions, then spread throughout the country with the same production technique ^[5]. The existence of shirataki is increasingly widespread in other countries, along with the increasing public demand for a healthy diet. 

For centuries, konjac tubers have been cultivated in Asian countries as a food source and ingredient in traditional medicine. Amorphophallus konjac is a perennial plant belonging to the Araceae family. In Indonesia, shirataki is made from porang tubers or iles-iles (Amorphophallus muelleri), which are still included in the Araceae family. 

Porang is one of Indonesia’s local tubers with high prospects and value in the global market because of its high glucomannan content. However, porang tubers also contain high anti-nutritional compounds, such as calcium oxalate, which can cause health problems, so certain treatments are needed to process porang tubers. Hence, they are safe for consumption ^[6]. 

BENEFITS OF SHIRATAKI 

Although its macronutrient content, such as carbohydrates, protein, and fat, is low, shirataki is high in glucomannan fibre, which is beneficial for digestive health. Based on the Food Data Central United States Department of Agriculture, shirataki has a fibre content of 2.7 g/100g, much higher than white rice 0.4 g/100g and a calorie content of 9 kcal lower than rice, which is 130 kcal ^[7,8]. 

This fibre helps smooth bowel movements and lowers blood sugar levels, so it can also support weight control. Research on mice shows that shirataki increases intestinal transit time, lowers body fat levels, and improves insulin sensitivity. This proves that the fibre in shirataki has the potential to control diabetes and metabolic syndrome ^[9]. 

Another study stated that Konjac glucomannan has great potential as a functional food for treating type 2 diabetes mellitus. Regular consumption of glucomannan can lower fasting blood sugar levels, increase glucose tolerance, and reduce insulin resistance in patients with type 2 diabetes. In addition, this fibre also supports weight management by providing a longer satiety effect and reducing calorie intake, an important factor in controlling diabetes. 

SHIRATAKI PROCESS 

Traditionally, farmers make konjac flour by cleaning konjac tubers, slicing them, air-drying them, and then grinding the sliced ​​konjac tubers. 

Today, konjac flour is commercially produced in several steps. The outer surface of the tuber is washed to remove dirt and soil. After cleaning, the tuber is sliced ​​into small pieces and dried using a hot air dryer emitting sulfur dioxide as a bleaching agent to prevent the konjac pieces from darkening. The dried pieces are then crushed to produce coarse konjac flour. This flour still has a fishy odour and a sharp taste. 

Regular konjac flour (food grade) is produced by removing impurities such as starch, protein, cellulose, and low molecular weight sugars from the crushed flour through cyclone filtration or alcohol precipitation. 

The alcohol precipitation process involves several washes with ethanol to remove low molecular weight sugars such as D-glucose and D-fructose in the flour, followed by extraction in water at room temperature. Pure konjac flour (neutraceutical grade) is produced without the addition of silicon dioxide ^[11]. 

After the konjac flour is obtained, the next stage is the formation of the dough by mixing the konjac flour with water until the dough becomes thick and homogeneous. This dough is then moulded into noodle strands using a special mould. Once formed, the noodle strands are boiled in boiling water for about 30 minutes at 70°C to strengthen their texture. 

The last stage is cooling and drying, where the boiled noodles are cooled in cold water to stop the cooking process, then left at room temperature before being dried in an oven for 8 hours at a low temperature, around 40°C, to ensure that the noodles are completely dry and ready to be packaged ^[1]. The noodles are then ready to be processed easily and quickly into various variations of processed foods. 

THE CRITICAL POINT OF SHIRATAKI’S HALALNESS 

The critical point of Shirataki’s halalness is using an auxiliary ingredient, ethanol. Based on the Fatwa of the Indonesian Council of Ulama No. : 10 of 2018 Concerning Food and Beverage Products Containing Alcohol/Ethanol, the use of alcohol/ethanol from non-khamr industries (either chemical synthesis [from petrochemicals] or non-khamr fermentation industry) for food product ingredients is permissible if it is not medically harmful ^[12]. 

Therefore, it must be ensured that the source of ethanol and its use are not harmful. In addition, it must be ensured that halal product production does not contaminate non-halal substances from raw materials, facilities, or workers. 

FOOD SAFETY STUDY OF SHIRATAKI 

Konjac tubers naturally contain anti-nutritional compounds like calcium oxalate, which can cause health problems ^[12]. Consumption of calcium oxalate can cause itching, burning sensation, and irritation to the mouth, skin, and digestive tract. Oxalic acid binds calcium so that calcium absorption is less than optimal. 

Excessive calcium absorption can result in hypocalcemia and fatal paralysis. In addition, if consumed excessively, calcium oxalate and oxalic acid can cause kidney problems. Therefore, pretreatment is needed to remove the calcium oxalate in konjac tubers before being used as raw materials in the food industry and other industries ^[13]. 

The washing process with ethanol helps dissolve and remove calcium oxalate from konjac flour because ethanol acts as a solvent for compounds not soluble in water, including oxalate. As the ethanol concentration and the washing time length increase, more oxalate can be released from the flour, reducing its levels significantly ^[14]. 

Calcium oxalate levels can be reduced by boiling and soaking in salt or vinegar. This method is considered effective in reducing calcium oxalate levels ^[15]. Based on SNI 7939: 2020, porang flakes will have good quality and are not harmful if they contain a maximum of 30 mg/100g of calcium oxalate ^[16]. With these various treatments, the calcium oxalate levels in porang tubers can be managed to be safe for consumption and suitable for use in the food industry. 

Consumers need to ensure that the shirataki products they buy have BPJPH halal certification, one of which is through LPH LPPOM MUI. Halal certification guarantees that the product complies with halal principles and ensures that food safety aspects have been met. 

The halal certification process thoroughly examines the ingredients used and the processing method to ensure that the product is safe and suitable for consumption according to established standards. Thus, consumers not only get peace of mind regarding halalness but also a guarantee of the quality and safety of the products consumed. (***) 

REFERENCE : 

1. Jang HN, Kumayas TR, Romulo A. 2023. Physicochemical and sensory evaluation of shirataki noodles prepared from porang and tapioca flours. IOP Conf. Series: Earth and Environmental Science. 1169, 012101. doi:10.1088/1755- 1315/1169/1/012101 

2. Widjanarko SB, Affandi M, Wahyudi Z. 2022. A review on konjac glucomannan and hydrolysed konjac glucomannan. Food Research. eISSN: 2550-2166 

3. Rozali ZF, Wulandari E, Noviasari S. 2021. Analisis Hedonik Nasi Shirataki Ganyong (Canna Indica. L) Hedonic Analysis of Rice Shirataki Queensland Arrowroot (Canna Indica L). Journal of Innovation Research and Knowledge. 1(7) 319-326. 

4. Behera S, Ray RC. 2016. Konjac glucomannan, a promising polysaccharide of Amorphophalluskonjac K. Koch in health care. International Journal of Biological Macromolecules. 92, 942–956 

5. Food in Japan. 2023. About Japanese Food & Traditional Foods of Japan. https://www.foodinjapan. org/japan/shirataki/ 

6. Naisali H, Utoro PAR, Witoyo JE. 2023. Review Keragaman dan Metode Pengolahan Umbi-Umbian Lokal Nusa Tenggara Timur. Jurnal Pangan dan Gizi. 13 (2), 1-17. 

7. Food Data Central. 2020. [HISTORICAL RECORD]: SHIRATAKI NOODLES. U.S. DEPARTMENT OF AGRICULTURE. Agricultural Research Service. https:// fdc.nal.usda.gov/fdc-app.html#/ food-details/803795/nutrients 

8. Food Data Central. 2019. Rice, white, long-grain, regular, enriched, cooked. U.S. DEPARTMENT OF AGRICULTURE. Agricultural Research Service. https://fdc.nal.usda. gov/fdc-app.html#/food-details/168878/nutrients 

9. Zhou Y, Qin J, Wang Y, Cheng Y. 2019. Gastrointestinal and metabolic effects of noodles-based konjac glucomannan in rats 63, 1997 http:// dx.doi.org/10.29219/fnr.v63.1997 

10. Fang Y, Ma J, Lei P, Wang L, Qu J, Zhao J, Liu F, Yan X, Wu W, Jin L, Ji H, Sun D. 2023. Konjac Glucomannan: An Emerging Specialty Medical Food to Aid in the Treatment of Type 2 Diabetes Mellitus. Foods, 12, 363. https://doi.org/10.3390/ foods12020363 

11. Chua M, Baldwin TC, Hocking TJ, Chan K. 2010. Journal of Ethnopharmacology 128: 268– 278. https://doi.org/10.1016/j. jep.2010.01.021 

12. Fatwa MAJELIS ULAMA INDONESIA Nomor: 10 Tahun 2018 tentang PRODUK Makanan dan Minuman yang Mengandung Alkohol/Etanol 

13. Naisali H, Utoro PAR, Witoyo JE. 2023. Review of Diversity and Processing Methods of Local Roots and Tubers of East Nusa Tenggara Jurnal Pangan dan Gizi p-ISSN: 2086-6429 13 (2) 

14. Faridah A, Widjanarko SB. 2013. Optimization of Multilevel Ethanol Leaching Process of Porang Flour (Amorphophallus muelleri) Using Response Surface Methodology. International Journal on Advanced Science Engineering Information Technology. 3 (2): 74-80. https:// doi.org/10.18517/ijaseit.3.2.309 

15. Quddus AA, Hambali E, Rahayuningsih M, Kartika IA, Budijanto S. 2024. Various Methods of Reducing Calcium Oxalate Levels in Tubers: A Review. Jurnal Biota 10 (1): 52-61. https://doi.org/10.19109/ Biota.v10i1.20473 

16. Badan Standardisasi Nasional. (2020). SNI 7939:2020 Serpih porang (Amorphophallus muelleri Blume) sebagai bahan baku. Jakarta: Badan Standarisasi Nasional.