Conventional and Scientific uses of Rice-washed water: A Systematic Review

Abstract

Rice is considered the king of cereals. It is the only cereal that is being consumed by half of the population in the world. Rice and rice products have potential health benefits. One such rice aided product is rice washed water which is discussed in this article. Rice-washed water, which is commonly regarded as waste water and discarded, is a rich source of minerals and nutrients. The processing of rice washed water, nutritional analysis; edible fungi productions are detailed in this review. The article goes into detail about rice-washed water, which has been used for various purposes since our ancestors’ time. The article provides a comprehensive report on the uses of rice-washed water in plant growth, Ayurveda, food, Cosmetics and a variety of other applications. Rice washed water is being utilized for various ailments since primitive times. The detailed report on the treatment utilizing rice washed water is also provided in this article. There are scarce researches with rice washed water, this article address the conventional uses of rice washed water, which can be taken up by the research community which needs more scientific validation. This review article also includes details about the composition and a variety of other important information about rice-washed water.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05722-2.

Introduction

India ranks among the top countries in the world in terms of rice cultivation and production. Rice, also known as Oryza sativa L. Rice is a food crop that is consumed by half of the world's population because it provides all of the calories required for daily activities. Rice is one of the agricultural commodities produced around the world. Rice contains all of the essential nutrients and minerals, as well as being a good source of carbohydrates. There are numerous rice varieties as a result of biotechnology advancement. Their cultivation method can also be modified based on the geographical and tropical conditions of the cultivation site. However, the growth process is the same regardless of the conditions. It is well known that rice and rice products such as rice bran and rice bran oil have equal benefits in health and skin care applications (Sugano et al. 1999). Rice-washed water is one such rice-aided product.

As of October 8, 2021, the number of research projects that used rice-washed water is very low, as shown in Fig. 1. This prompted the authors to probe on the topic of rice-washed water its various applications. To the best of our knowledge, this is the first report and compilation of the previously reported research work on rice-washed water and its applications.

Fig. 1.

The number of hits for the keyword “rice washed water” in various database

It is customary to wash the rice before cooking and to discard the washed rice water. In this review, the authors would like to highlight some of the important aspects of rice-washed water, which has been used for a variety of purposes around the world but still requires more scientific validation. To clean oil pots, the face, and the hair Rice washed water has been used in China since ancient times, and Chinese households have learned these from personal experience. The ethnic Yao ladies of Huangluo, China, are living proof of the Rice Water usage tradition (Khadge and Bajpai 2018). Female rice farmers in China, Japan, and other Southeast Asian countries used rice water to bathe and wash. With an average hair length of 6 feet, the women became the “longest hair village in the world” according to the Guinness Book of World Records. Until the late 1980s, the women had no grey hair.

The Yao ladies believe that the fermented rice water they use to purify their hair keeps their hair long, black, and smooth. Rice water can decongest and manage these ladies’ long hair (Khadge and Bajpai 2018). In times of scarcity, rural women in Kothein village, Myanmar, are said to use rice-washed water to clean their dishes. Aye 2018 praised and highlighted the village women’s wise and useful water management. Due to the presence of significant nutrients, rice washed water is used for punnac preparation and to wash potteries during the drought season (Hettiarachchi and Jayasooriya 2016). Rice washed water is used as feed instead of water for cattle and goats in many parts of the world (Rifky et al. 2018; Sikder et al. 2015).

Rice washed water is a white milky liquid obtained after washing rice. According to traditional knowledge, rice washed water is used in various skin care, hair care, and other adjuvant for various ailments. Inspired by the traditional uses of rice water for skin and hair care, several skin care products and hair shampoos are now commercially available in the market. Rice water soaps and bathing gels are widely available in the market. Pantene, a well-known hair shampoo manufacturer, claims that rice water is one of the ingredients in their most recent hair shampoo formulation. Despite the lack of proper scientific validation, numerous beauty blogs report on the direct use of rice-washed water for skin care, hair care, and plant growth (Nabayi et al. 2021a, b). Recently, patents have been filed on the synthesis of metallic and non-metallic nanoparticles using rice-washed water from various sources. Recent reports claim that floating microbial fuel cells using Baker’s yeast as a biocatalyst can generate electricity from waste water from Japanese rice-washing processes. The floating microbial fuel cell had a power density of 1 mW/m² (Nguyen and Taguchi 2020).

Brown rice is one of the more popular types of rice because, because it is typically milled, it is more nutrient-dense than white rice. Whole brown rice was found to have a higher concentration of nutrients like protein, lipids, minerals, and vitamins when compared to refined white rice. The entire grain of brown rice has more dietary fibre than white rice. This is as a result of the substantial amount of dietary fibre present in the outer bran layer. Brown rice contains more protein than white rice because protein is heavily concentrated in the outer bran layer of the rice grain. White rice and brown rice both contain about 16 different amino acids (Thomas et al. 2015). Lipids are also found in the brown rice outer bran. Exiguous research has been done comparing the composition of brown/white rice washed water. Depending on the geographical area and the minerals present in the wash water, the composition will vary.

Treatment of rice water to analyze the components

To precipitate organic substances, rice-washing water is acidified to pH 4. The removal rate is 85% (Saito et al. 1983). A qualitative analysis of nutrients and minerals in rice-washing water was performed using commonly used instruments and reagents. Under acidic conditions, yeasts capable of extracting Chemical Oxygen Demand (COD) from rice-washing wastewater were isolated. Hansenula anomala extracted approximately 40% of the organic compounds found in rice-washed water (Saito et al. 1983).

A comprehensive scientific theory, on the other hand, remains elusive to this day. It has been demonstrated that native starch granules can function as a Pickering emulsifier, removing grease. This eco-friendly detergent is a promising cleaning agent because it has no negative effects on the eco system's stability (Chen et al. 2019). Rice washing water contains pH, crude protein, crude ash, sugar, starch, crude fat, minerals (Fe, Cu, Zn, Mn, Mg, K, Na, Ca, Cl, P, Se), and vitamins (VB2, VE). The rice washing water had five efficacies, according to the results of the component analysis: decontamination, hairdressing, fertilizer, medication, and deodorant (Peng and Du 2013; Qiao et al. 2013).

Several lots of California brown rice of the short-grain variety were found to have a wide range of thiamine levels when tested using the rat-growth method (208 to 298 per 100 g, raw weight basis). There was no significant loss of thiamine when brown rice was thoroughly washed with 5 changes of water. Partially polished rice was found to have nearly 70% more thiamine than untreated brown rice. Partially polished rice lost more thiamine than brown rice due to washing (about 20%). This higher loss was caused by the washing away of clinging rice polish that adheres to partially polished grains (Miller 1945). The most common taxa found in fermented rice washed water were Proteobacteria (62%), Firmicutes (28%), Cyanobacteria (10%), and Bacteroidetes (0.5%). The bacteria found in the core rice washed water include Trabulsiella, Pseudomonas, Serratia, Lactobacillus, Erwinia, Enterobacter, Clostridium, and Acinetobacter (Chen et al. 2021).

NaOCl, K₂S₂O₅, and irradiation were used to test the preservation of starch obtained from rice washing water. The development of microbes in the collected starch was prevented by lowering the pH to 3 and adding 60 ppm K₂S₂O₅. When the starch was fermented, irradiation (0.5 and 1.0 mrads) demonstrated disinfectant activity as well as increased alcoholic production (Saito et al. 1987). During cold water washing, raw milled rice loses approximately 60% of its nicotinic acid (I), whereas parboiled milled rice, which has nearly twice as much nicotnic acid (3.2 mg per 100 g), loses approximately 12% (Swaminathan 1941). Thiamin losses in polished rice were 42% and 13% during washing with tap water and distilled water (free of Cl⁻), respectively, while vitamin losses were 63% and 23% during washing and cooking with tap water and distilled water, respectively (Motooka et al. 1981).

The treatment of rice-washing wastewater with varying pH and chitosan concentrations was investigated. Chitosan concentrations did not significantly improve turbidity reduction at pH 4 and 5, but significantly improved turbidity reduction at pH > 6 when compared to control experiments. However, regardless of chitosan content, wastewater turbidity reduction was greatest at pH 4 and gradually decreased as pH increased. The most efficient way to remove wastewater suspended particles was to reduce the pH of the wastewater to 4 and then centrifuge it, resulting in a 99% reduction in turbidity. The effect of different wastewater suspended solids concentrations and acids used to modify pH on turbidity reduction were negligible (No et al. 1994). The influence of rice on the quality of rice washed water preparation was investigated. The hydrolysis-Fehling solution titration with starch content and water characteristics using rice washes as indicators determined the starch content in rice-washed water. The characteristics of rice-washed water were measured using a spectrophotometric ultraviolet technique, and the influence of Japanese rice particle size, indica rice, round glutinous rice, and long glutinous rice on rice wash water quality was investigated. A thorough examination revealed that the level of starch and the properties of rice washed water made from long glutinous rice fine powder were the highest.

The check test revealed the highest adsorbability. The rice-washed water can be used to cook the meal with long sticky rice (Wang et al. 2018). It was reported that a membrane method was used to recover useful components such as protein from rice-washing water produced during the processing of washed rice. A hollow fibre ultrafiltration, spiral wound nanofiltration, and reverse osmosis kits for home water purification were tested, as well as a dead-end Amicon cell to evaluate appropriate membranes. The ultrafiltration module extracted no valuable components or protein from the rice-washing water, whereas the nanofiltration and reverse osmosis modules did. Protein concentrations in nanofiltration and reverse osmosis concentrates were 18 and 22% in rice-washing water containing about 9% protein, respectively, and were approximately 2 and 2.4 times higher than those in feed (Chung and Park 2002).

Applications of rice washed water

Rice water source for fungi production

Entomopathogenic fungi such as Verticillium lecanii and Metarhizium anisopliae were cultured in various media to maximize fungus biomass. Rice washed water is also used to cultivate these fungi (Jitendra et al. 2012). Several agricultural products and byproducts, as well as rice washed water, were tested for their ability to mass produce entomopathogenic fungi: Beauveria bassiana (Bals.) Vuil. Paecilomyces fumosoroseus (Wize) and Verticillium lecanii were identified. Rice and wheat washing water also aided in the growth and sporulation of all three fungi studied. Rice wash water produced the highest spore count in M. anisepliae (Patel et al. 1990; Sahayaraj and Namasivayam 2008). Rice washing water, a potential medium for lactic acid bacteria, was investigated for use as an animal probiotic drink. The pattern of Lactic acid bacteria development in rice washed water investigated using a completely randomized design and a factorial design revealed the highest number of bacteria in 1:3 washed rice-water by the first wash at 12 h and 1:2 rice-ratio by the first wash at 30 h. The 1:3 rice-water washing ratio first and 1: 1 rice-water washes second provided an early rapid environment for development. The results show that rice water can be used as a probiotic drink within 12 to 42 h of fermentation (Gil et al. 2015).

The effect of rice-washed water bleaching products, fried products with bran, and raw Atractylodis rhizoma products on spleen deficiency rats, as well as their dryness nature, provide scientific data for clinical Atractylodis rhizoma medication. All Atractylodis Rhizoma processed products have a certain effect on spleen deficient rats; the effects of rice-washed water bleaching products and fried products with bran are significantly better than raw products; they all have a good effect of strengthening the spleen and stomach, regulating gastrointestinal function and secretion (Gong et al. 2017).

Rice water as chicken feed

The effects of concentrated rice-washing water on broiler chicken growth and lipid peroxidation levels were investigated. Rice washed water has been shown to be a potential high-energy feed resource, and rice washed water dried at high temperatures has been shown to alter lipid peroxidation in broiler chickens via increased antioxidant activity (Ijiri et al. 2013). In order to determine the optimum dose of chicken manure and rice water washing on eggplant growth and crop yield, the effect of dosing chicken manure and rice water washing on eggplant growth and crop yield was studied, as well as the effect of the interaction between a dose of chicken manure and rice water washing on eggplant growth and crop yield. According to the study's findings, providing chicken manure and water washing rice can improve eggplant development and crop yield. The true interaction occurs on plant colonisation eggplant in chicken manure treatment doses with a dosage of rice washing water (do Rego et al. 2019).

Bacterial cellulose (BC) is a biopolymer with numerous applications ranging from medicine to electronics. To generate BC, Komagataibacter xylinus was fed two types of liquid waste: tofu liquid waste and rice-washed water. The structure of BC was studied using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The tofu liquid waste yielded a higher yield than the rice-washed water after 15 days of fermentation. Both BC's FT-IR spectra exhibited a pattern similar to that of conventional cellulose. According to the findings, both tofu liquid waste and rice-washed water have the potential to be used as BC production media (Apriyana et al. 2020). Sun created and patented a polymeric anti-bacterial preservative film in 2016. Bacillus, Pseudomonas, Trichoderma, and yeast are all inhibited by this film. Rice-washed water was an important component in the film. Lactic acid bacteria are made using rice-washed waste (Buang 2019).

Using a spray coating technique, rice-washed water was used to treat kenaf fibres. The effect of treatments on mechanical and interfacial properties was evaluated in comparison to rice-washed, water-treated kenaf fibre. Tensile and interfacial cleave strength of kenaf fibre improved after treatment with rice washed water. Thermal strength of kenaf fibre treated with rice water was found to be increased by TG analysis. The treatment of kenaf fibres with rice washing water improved their mechanical and interfacial properties (Park et al. 2015).

Rice water as probiotics

Rice-washed waters are used in the preparation of Soidon starters (fermented bamboo shoots). It has been reported that the addition of rice washed water (high in starch) during soidon starter preparation may have favoured Bacillus population, enhancing the probiotic nature of the soidon (Jeyaram et al. 2010). The pungent smell, bitterness, and fishy taste of Gastrodia elata Blume were reported to be reduced when treated with rice-washed water and rice-bran solution fermented with Lactobacillus brevis and Lactobacillus plantarum. The treatment in fermented rice washed water also changed the biobenificial contents of the species (Chang and Ahn 2011). Cattle / buffaloes in Sundarbans delta are fed with paddy straw along with rice gruel, rice washed water, rice bran and kitchen waste (Das and Tripathi 2008).

‘Insects tea’ is not only a traditional drink for the ethnic minority of southwestern China, but it is also one of China’s traditional exports, according to Li Shizhen’s “Materia Medicas Compendium”. Insect tea is made from the excrement of insects that feed on plants. It has a low dosage, a pleasant tea flavor, little tea residue, and excellent transparency. Insect tea was used to relieve summer heat, protect the spleen and stomach, and aid digestion. According to modern research, bug tea is safe and nutritious, and it reduces blood fat, blood volatility, and hypoglycemia. These teas are intended for use in the home. To protect the tea leaves from insects, rice-washed water is sprayed on them (Xu et al. 2013). A ready-to-drink Bitter gourd beverage was developed. As a debittering step, the sliced bitter gourd was soaked in rice washed water (Chern et al. 2018).

Ayurveda and Chinese medicine

In several Chinese medicinal combinations rice-washed water has a prominent role. In most of the combination cerebrovascular and cardiovascular diseases rice-washed water is used (Li et al. 2007). Dushivishari gulika along with rice washed water as adjuvant is advised to patients with Visphota kushta (blistering skin disease) is characterized by transparent blisters with thin skin covering according to Ayurveda (Vagbhata 2010). In traditional Chinese medicine, Jin-Changzhu must be treatment with rice-washed water before it is used therapeutically for the removal or reduction of poisonous and dehydrating chemicals Atractylodin and acetyl atractylodinol (Ding et al. 2000).

Tandulodaka is the Ayurvedic term for rice water. According to Bhaishajya Ratnavali 8/32, it is considered derivative dosage in the form of cold infusions. In Ayurvedic terms, it is used as anupana (co-drink). People in extremely cold weather, as well as those with asthma or a severe cough, should avoid taking Tandulodaka formulations (https://www.easyayurveda.com/2017/10/11/rice-water-tandulodaka/). Mixtures with rice washed water are thought to enhance the pharmacological activities of medicinal plants (Juárez-Vázquez et al. 2013). This results in a variety of formulations that use rice-washed water. Mehavajra Rasa is one of the Ayurvedic compounds used to treat Diabetes Mellitus Type -2. Shilajatu, Rasasindoor, Kantlauha, Swarnmakshik, Manahashila Trikatu, Triphala, Bilva, Jeerak, Kapith, Haridra are the compounds' ingredients. This medication must be taken with 500 mg of Nimbachurna, Ghrita, and rice-washed water (Richa and Sachdev Kamal 2017).

A composite of Scorzonera albicaulis Turcz, brown sugar, and rice-washed water for the treatment of lithiasis such as hepatolithiasis, cholecystolithiasis, bile duct calculus, renal calculus, and urethral calculus was developed (Yin 2007). It is surprising that at the end of 6 days of menstruation, the woman is required to wash her hair with CHENGHI, rice-washed-water boiled with specific herbs, as practiced by the Meitei community of Manipur (Singh 2004). Table 1 describes ancestral knowledge about the use of rice-washed water for various health issues.

Table 1.

Traditional formulation incorporating rice-washed water for various health issues

S. no	Name of species used with rice-washed water	Disease	Mode of administration	Human/Cattle	Region	References
1	Actinopteris radiata	Snake bite	One spoon of root paste mixed with that of cow ghee is administered with rice washed water	Human	Tribal people of Eastern Ghats, Andhra Pradesh	[S1]
2	Erythrina variegata	Backache	One spoon of shade dried stem bark powder is taken with one cup of rice washed water only once in night for 15 days	Human	Tribal people of Eastern ghates, Andhra Pradesh	[S1]
3	Euphorbia tirucalli linn	Galactagogue	Latex mixed with that of papaya is taken with rice washed water daily	Human	Tribal people of Eastern ghates, Andhra Pradesh	[S1]
4	Cucurbita maxima duch	Dengue fever (Kuntu roga)	Paste of the fruit stalk rice washed water is applied in joints of the legs for a week	Cattles	Uttara Kannada, Karnataka	[S2]
5	Premna corymbosa rottl	Diabetics	Paste of roots (about 10 g) along with rice washed water orally twice daily	Human	Tribes of Orissa	[S3]
6	Desmostachya bipinnata + Sida rhombifolia	Blood stool	Desmostachya bipinnata root and bark, root of Sida rhombifolia grinded together with rice washed water	Human	Prescribed in Ayurveda	[S4]
7	Desmostachya bipinnata	Menstrual disorder	Root pounded in rice washed water, taken being mixed with powder of cumin seed (Cuminum cyminun) and sugar	Humans	Prescribed Ayurveda	[S4]
8	Desmostachya bipinnata	Menstrual disorder	Desmostachya bipinnata root and Phyllanthus fraternus pounded in rice washed water, taken for 7 days twice daily morning and evening	Humans	Prescribed Ayurveda	[S4]
9	Lobelia nicotianaefolia	Sores	The root paste is prepared in rice-washed water and applied externally for sores	Humans	Kunabi Tribe of Karnataka	[S5]
		Mumps	A bit of paste in limejuice is given orally
10	Withania somnifera (L.) Dun	Male impotency	Root Paste is prepared in rice washed water and one spoon a day is taken for 45 days	Human	Uttara Kannada, Karnataka	[S6]
11	Syzygium cumini L and diospyrus hispida	Yellow purging during pregnancy	A mixture of leaf extract of the Syzygium cumini, Diospyrus hispida leaf extract and rice washed water is prepared and the cattle is allowed to drink it	Cattle	BARGARH DISTRICT OF ORISSA	[S7]
12	Alangium salvifolium	Conjunctivitis	Pounded leaves of the plant are tied in a fine cloth and dipped in fermented rice water for some time. Few drops of the contents are squeezed into the opposite ear of the patient as eardrops	Human	KORAPUT DISTRICT, ORISSA	[48]
		Snake bite	Stem bark (10–20 g) crushed with rice washed water is administered twice in the first one hour of snake bite	Human	ORAON TRIBE OF JASHPUR DISTRICT, CHHATTISGARH
13	Butea monosperma	Goiter	The root of the plant is ground with rice washed water and the paste is applied on neck	Human	KORAPUT DISTRICT, ORISSA	[S8]
		Infertility	5 g inner bark extraction added to a cup of rice washed water with a pinch of zeera powder, two grains rice powder mix is given orally before breakfast for 3 days during	Human	ADILABAD DISTRICT, ANDHRA PRADESH	[S9]
14	Terminalia arjuna	Urinary infection	Consumption of dried bark powder along with rice washed water	Human	Sundargarh District, Orissa	[S10]
15	Punica granatum	Dysentery and diarrhoea	Leaf, bud or unripe fruit is made to paste along with rice washed water and administered orally along with a minute pinch of opium. Half cup taken twice a day to check diarrhoea	Human	Gond tribe of Bhandara, Maharashtra	[S11]
16	Elephantopus scaber Linn	Irregular menstruration	Root paste with rice washed water is taken in empty stomach for 3–5 days for irregular menstruation	Human	Kalahandi District, Orissa	[S12]
17	Alstonia scholaris	Dysentery	2 spoonfuls of latex with a glass of decoction of Piper nigrum seeds mixed with rice washed water is administered daily twice for 2 days	Human	Vizianagaram and Srikakulam Districts, Andhra Pradesh, India	[S13]
18	Pongamia pinnata (L). Pierre	Pain due to swelling	Paste of both the plant leaves in rice washed water is applied over the affected part	Human	Gulbarga district, Karnataka	[S14]
19	Asafetida	To detach still born infant from mother’s womb	Asafetida is pounded with common salt and mixed it with rice washed-water and administered by the laboring women	Human	TRIBAL group of Andhra pradesh	[S15]
20	Tamarindus indica L	Malaria	Fruit juice with rice washed water and jaggery (palm sugar)	Human	Tumkur district of Karnataka	[S16]
21	Indigofera barberi	Expel intestinal worms, skin diseases, peptic ulcers	Whole plant powder (5 g) is taken along with rice washed water once a day for 10 days	Human	Nakkala and other tribal physicians	[S17]
22	Cyclea peltata	Leucorrhoea	Leaf paste mixed with rice washed water is orally taken, 2–3 times a day for 3 days	Human	Kodagu district, Karnataka	[S18]
23	Abutilon indicum	Jaundice	The paste of seven leaves with seven black pepper is taken in empty stomach with rice washed water in the early morning	Human	Kantapada block of Cuttack district of Odisha	[S19]
		Dysentery	Plant crushed with rice washed water is taken twice daily	Human	Erode district, Tamil Nadu, India	[S20]
24	Cynodon dactylon	Menorrhea	Hibiscus rosasinensis flower, old molasses and whole plant are crushed with rice washed water	Human	Tribals of Shahdol, Madhya Pradesh, India	[S21]
25	Celosia cristata L	Body swelling (dropsy)	Ash of the leaves is rubbed on the body and its juice is given orally as diuretic along with rice washed water	Human	Tanchongya—Moragful Naramuk, Rajsthali, Bangaladesh	[S22]
26	Erythrina variegata Linn	Backache	One spoon of shade dried stem bark powder is taken with one cup of rice washed water only once in night for 15 days	Human	Visakhapatnam District, Andhra Pradesh, India	[S23]
27	Lamellidens corrianus	Impotency	Dried flesh of the animal with aquatic earthworms (Limnodrilus spp) and (Unio) bark of Achy ran thus asper (L), rice washed water and Pipper nigrum is consumed	Human	SINGHBHUM PLATEAU, JHARKHAND, INDIA	[S24]
28	Leucas aspera spreng	Snake bite	Along with that of garlic, ground, mixed in rice washed water, given orally	Human	Rayalaseema region, Andhra Pradesh, India	[S25]
29	Alangium chinense	Cure from dog bite	Root bark and black pepper seeds (5–7) crushed to paste, mixed with a cup of rice washed water and then taken after Dog Bite	Human	West Dinajpur in Bengal, India	[S26]
30	Gossypium herbaceum L	Cure for rat bite	leaves crushed with rice washed water applied on affected part	Human	Nizamabad District, Andhra Pradesh, India	[S27]
31	Eclipta alba (L.)	Pneumonia, digestion	Whole plant paste mix with rice washed water and taken orally	Human	Tai Phake of Assam, India	[S28]
32	Gomphrena serrata L	Cold and cough	Whole plant with leaves of Tephrosia purpurea and seeds of Piper nigrum are taken in equal quantities and ground. 50 g of paste with rice washed water is administered daily once for 3 days	Human	Visakhapatnam and Vizianagarm Districts, Andhra Pradesh, India	[S29]
33	Cissus quadrangularis L	Asthma and cough	500 ml juice of 200gm whole plant with Allium sativum bulb claves taken in similar proportion with rice washed water given once a day	Buffaloes and cows	Ahemednagar district, Maharastra	[S30]
34	Asparagus racemosus	Diabetics	Roots of the plant along with Cuminum cyminium seeds one teaspoon of each taken orally with rice washed water once a day for 15 days	Human	Ahemednagar district, Maharastra	[S30]
		To improve lactation	500 g powder of Root tubers given orally with rice washed water to buffalos and cows, once a day for 15 days	Buffaloes and cows
35	Opuntia stricta	Menorrhagia and Metrorrhagia	10 ml fruit juice mixed with 10 ml 0f rice washed water and a spoonful of sugar is administered twice a day for 3 days till to cure	Human	Sudi Konda Forest, East Godavari District, Andhra Pradesh	[S31]
36	Costus speciosu	Jaundice	Paste of 100 g of rhizome mixed with rice washed water and palm sugar, sieved and taken one glass of it twice daily in the morning in empty stomach and in evening for 3 days	Human	Assam, Bengal, India	[S32]
37	Alstonia scolaris	Fever and throat irritation	Bark juice + Rice washed water taken orally for 2 days	Human	Koppal district of Karnataka	[S33]
38	Marsdenia tenacissima	Post-natal pain	Root of the plant crushed with polished rice washed water and the paste (2–3 teaspoon) is taken twice daily	Human	Bargarh district of western Odisha	[S34]
39	Heliotropium indicum L	Post-natal pain	Root of the plant crushed with polished rice washed water and the paste (1–2 teaspoon) is taken twice daily	Human	Bargarh district of western Odisha	[S34]
40	Amaranthus	Menorrhoea	Amaranthus root (10 g) along with rice washed water is taken twice daily for 3–4 days	Human	Bolangir, Orissa, India	[S35]
41	Basella	Irregular periods	paste of root of red Basella (10gm.) along with rice washed water is taken in the morning in empty stomach for 1 month	Human	Bolangir, Orissa, India	[S35]
42	Hibiscus rosa-sinensis	Menorrhoea	Whole plant, flower of Hibiscus rosa-sinensis, old molasses are crushed with rice washed water and taken once daily in empty stomach	Human	Bolangir, Orissa, India	[S35]
43	Ferronia limonia	Menorrhoea	paste of the leaf Ferronia limonia (15gm.) & leaf of bamboo (15gm.) along with rice washed water is taken twice daily	Human	Bolangir, Orissa, India	[S35]
44	Holarrhena pubescens	Menorrhoea	The powder of the Holarrhena pubescens bark (one spoon) along with rice washed water is taken twice for a week	Human	Bolangir, Orissa, India	[S35]
45	Phyllanthes neruri	Menorrhoea	Paste of whole plant or fruit of Phyllanthes neruri (5gm.) along with rice washed water is taken twice daily in empty stomach for 3–4 days	Human	Bolangir, Orissa, India	[S35]
46	Streblus asper	Cure for white discharge along with pus and blood	The bark of the root of Streblus asper (5gm.) along with rice washed water is taken twice daily	Human	Bolangir, Orissa, India	[S35]
47	Syzygium cuminii(L.)	Menorrhoea	Soft leaf or the bark juice of Syzygium cuminii(L.) (10 ml.) along with rice washed water is taken twice in empty stomach	Human	Bolangir, Orissa, India	[S35]
48	Sida acuta	Diarrhoea	Wholeplant of Sida acuta together with rice washed water is grounded to a fine paste and the paste is given internally	Human	Sundargarh district, Orissa, India	[S36]
49	Phoenix accaulis	Vomiting	Immature fruit is made in to a fine paste and the paste thus obtained is taken with rice washed water	Human	Sundargarh district, Orissa, India	[S36]
50	Phyla nodiflora (L.)	Jaundice	Wholeplant (10 g) and 7 black peppers are grounded to a fine paste and the paste thus obtained is taken on empty stomach, along with rice washed water of 3 consecutive days	Human	Sundargarh district, Orissa, India	[S36]
51	Tephrosia purpurea	Leucorrhoea haematuria	Dried leaf powder of Tephrosia purpurea and pasted rice powder in equal quantities is-taken orally on empty stomach followed by rice washed water	Human	Sundargarh district, Orissa, India	[S36]
52	Alstonia scholaris (L.)	Fever	One handful of bark of Alstonia scholaris (L.) R. Br ground with rice washed water to prepare a juice and one teaspoonful of juice is taken internally with a cup of rice washed water, daily twice for 3 days	Human	Shimoga district, Karnataka, India	[S37]
53	Ficus racemosa L	Piles	Bark powder mixed with rice washed water and filtrate taken orally with water for 2 weeks	Human	Shimoga district, Karnataka, India	[S37]
54	Holoptelea integrifolia	Veterinary diseases and disorders	Bark and leaves ground with 15 pepper seeds, one bulb of garlic in rice washed water. Half liter of plant extract given to cattle, daily once for 1–2 days	Cattle	Shimoga district, Karnataka, India	[S37]
55	Nothapodytes nimmoniana	Scabies	Root ground with lime juice or rice washed water, applied over the infected region until cure	Human	Khare-vokkaliga community in Uttara Kannada district of Karnataka	[S38]
56	Graptophyllum hortense	Urticaria	Leaves crushed in rice washed water, applied over the affected part and given orally	Human	Khare-vokkaliga community in Uttara Kannada district of Karnataka	[S38]
57	Cocos nucifera	Vomiting	Tender leaves crushed in rice washed water and given orally	Human	Khare-vokkaliga community in Uttara Kannada district of Karnataka	[S38]
58	Amaranthus spinosus	Infertility in women	Juice of the root is mixed with rice washed water and administered orally for 3 days after menstrual periods	Human	Kerala	[S39]
59	Gloriosa superba	Infertility in women	Purified rhizome juicemixed with rice washed water is administered orally for 3 days at the menstrual periods	Human	Kerala	[S39]
60	Basella alba L	Irregular periods	The root paste along with rice washed water is taken in the morning in empty stomach for 1 month to cure irregular periods	Human	Mahendragiri Range of Hills, Eastern Ghats	[S40]
61	Carica papaya	Jaundice	The roots of Carica papaya along with the roots of Jasminum sambac and Lawsonia inermis are grinded with rice washed water to prepare the solution which is taken orally	Human	Mahendragiri Range of Hills, Eastern Ghats	[S40]
62	Nymphaea nouchalli	Diabetes	Rhizomes along with refined form of gur and root of Lawsonia inermis L. is grinded in the rice washed water	Human	Mahendragiri Range of Hills, Eastern Ghats	[S40]

S1–S40 provided in supplementary section

Cosmetics and anti-ageing

Everyone wishes to be beautiful. This is why, since the Vedic period, humans have used cosmetic preparations. Numerous cosmetic concoctions are mentioned later in the postwedic era, Kavya, Natya, and Ayurvedic treatises. Haramekhala is a humanity treatise that explains various cosmetic preparations that make use of basic herbal medicines. Haramekhala discusses various preparations for improving physical appearance and remaining youthful and charming. Rice washed water, along with Nasya and Strotonjana, was used in one of them for breast enlargement and shape (Archana et al. 2012).

With the help of some herbals and fermented products, a non-stimulating anti-aging soap was created. This soap's main ingredient and base was fermented rice-washed water. Others included herbal medicines, glycerin, essential oils, propolis, and so on (Park and Park 2013). Rice water is thought to be an anti-aging product. According to Marto et al. (2018) a hydrogel formulation made from rice-washed water has anti-aging properties and is compatible with the pH of human skin. It has also been reported that fermented rice washed water contains traces of kojic acid, which is an anti-aging agent.

Pitera is a fungi with the highest natural moisturising factor (Saccharomycopsis febuligera yeast). Pitera was isolated from fermented rice water (Khadge and Bajpai 2018). Pitera was used to remove makeup in two phases. The researchers attempted to use two naturally-derived components derived from Japanese traditional knowledge as hair-treatment compounds. Yu-Su-Ru (rice washing drainage water) and sericin are two of these components (produced from cocoon thread). Both have been inextricably linked with Japanese life science since ancient times. They both have one thing in common: they have been largely squandered, both in terms of effective natural resource exploitation and elsewhere. Every day, the Heian court women were said to comb their hair with Yu-Su-Ru. The remarkable efficacy of Yu-Su-Ru and sericin as hair-treatment ingredients, both of which are part of Japanese traditional medicine but are rarely used, is investigated here. As a consequence, we are now able to propose innovative hair care products out of this (Inamasu 2009).

Plant growth with rice washed water

Rice washed water is wastewater, and like with other wastewater, it should be recycled as part of good water management. This would equivalent to at least 504 billion L of rice washed water being created within this time frame, even with a modest assumption of utilizing just 1 L of water to wash every 1 kg of rice grains. Furthermore, by 2050, the demand for freshwater is predicted to rise by 55% globally. But if rice washed water is to be promoted for reuse in agriculture, its advantages must be demonstrated over the course of at least two steps. First, the liquid rice washed water itself contains the properties and nutritional levels that are favourable to plant growth. The use of rice washed water will promote crop growth and yield in the short- and long-term, as well as improve the biological and physicochemical soil features (Nabayi et al. 2021a). Long-term use of rice washed water advantages include the ability to progressively increase beneficial soil biota populations as well as soil nutrient concentrations (Nabayi et al. 2021b). These results show that the rice washed water is not an environment pollutant instead it increases the soil fertility.

Polished rice washing water (seihaku-mai in Japanese) puts a strain on grey water treatment. Rice washed water is fermented with milk by some farmers and used to manage healthy plant development. When rice washed water was fermented with cow's milk (RWWM), it was discovered that it produced combustible gas and protein debris, reduced pH early in the fermentation process, and produced lactic acid. Clavibacter michiganensis subsp. michiganensis (CMM), the causative agent of tomato bacterial canker, was also inhibited by RWWM, but not Bacillus subtilis, Staphylococcus aureus, or Escherichia coli. Lactic acid bacteria are involved in RWWM's antibacterial activities, and certain RWWM metabolites inhibit CMM development (Nakata et al. 2018).

The cabbage immersed in rice-washed water removes and cleans cabbage from Formaldehyde. Increasing the time of immersion removes more formaldehyde (Fang et al. 2014). To improve the cultivation of black beans, pollution-free natural fertilizers with several important elements (N, P, K) essential for the plant growth are developed The important ingredients in the fertilizer were rice washed water along with vegetable leaves and roots, fruit peel and nut, and other household wastes. More quantity of rice washed water in the fertilizer improves the plant growth and subsequently the yield (Zeng 2015).

Rice-washed water is one of the ingredients in a natural fertilizer that also includes dog-rabbit excrement, straw powder, river silt, sugar mud, strains, and traditional Chinese medicine liquid to boost strawberry growth (Zhou 2016). One of the key components of an eco-friendly soilless tomato nutrient solution is rice-washed water (Zhao 2013). Rice washed water was used as one of the components in the development of a nutritional organic flower fertilizer. This fertilizer is beneficial to flower growth and is inexpensive (Wang 2012).

The hydroponic system is becoming increasingly popular in Indonesia, but the fertilizer is expensive. Moringa leaf and rice washing water have a high mineral and vitamin content. A study on how pakcoy growth responds to the use of a low-cost organic liquid fertilizer made from moringa leaves and rice washing water was published. Organic liquid fertiliser is made from moringa leaves and fermented rice washing water. The study determined that the addition of the aforementioned organic liquid fertilizers increased the leaf width, length, number of leaves, and weight per sample (Sari et al. 2020).

Termites subterranean and Coptotermes curvignathus are the major pests of plantation species, most notably in rubber and oil palm. Entomo pathogenic bacteria, such as Bacillus thuringiensis, are a safe and environmentally friendly method for controlling these pests. There have been reports of pest control using rice washed water and coconut water in which B. thuringiensis media is propagated and golden snail meat flour is added. Its toxicity is being investigated in relation to the aforementioned termites (Pujiastuti 2018). Carbendazim is commonly seen post-harvest fungicide. An electrochemical sensor and a photocatalyst for the determination of Carbendazim was developed (Periyasamy et al. 2019). The real samples of Carbendazim obtained from rice-washed water and soil washed water was utilized for the studies.

Conclusion

The rice-washed water is a traditional ingredient which has several beneficial components. The washed rice water which has been discarded off has many magnificent uses and lacks scientific validation. The review article provides a better understanding of this traditional product in terms of its availability and its application and uses in the field of Ayurveda, medicine, plant growth and several other prominent areas. This review article will provide a better understanding about the rice-washed water and the utilization of the same in several other unexplored areas.

Supplementary Information

Below is the link to the electronic supplementary material.

Abbreviations

ppm

Parts per million

BC

Bacterial cellulose

RWWM

Rice washed water fermented with cow’s milk

Author contributions

AC investigated and wrote the manuscript, LP supervised, edited and corrected the manuscript, SCS and RMM corrected the manuscript, AP and RR edited the manuscript.

Funding

Not applicable.

Declarations

Conflict of interest

The authors declare that they have no conflict of interest.