2021 年 27 巻 3 号 p. 341-349
The purpose of this study was to develop sprouted brown rice (SBR), where germinated brown rice (GBR) is cultivated until the shoot and first leaf emerge. SBR is a combination of GBR, which contains high levels of GABA, and sprouts, which are known for their chemopreventive effects. This study showed that SBR with intact grains and almost no roots can be grown by anaerobic water cultivation using weakly acidic electrolyzed water. Amino acids in SBR, which are associated with secondary and tertiary functions, and phenols reached maximum contents after 14–19 and 7 days of culture, respectively, and GABA content (134 mg /100 g dw) was higher than that previously reported in GBR. In addition, the viable cell count of fresh SBR after washing satisfied conditions for raw consumption. SBR has high potential as a novel approach to consuming brown rice with enhanced functionality.
The incidence of lifestyle-related diseases, such as diabetes, high blood pressure and cancer, is increasing worldwide, not only in developed but also in developing countries (Sarrafzadegan 2009). According to the latest findings of the Global Burden of Disease Study (GBD 2017 Disease and Injury Incidence and Prevalence Collaborators 2018), 20 % of the world's mortality is related to eating habits, and diets are mostly affected by very low intakes of whole grains, vegetables, fruits, nuts and seeds, which had a greater effect than high intakes of salt and trans-fatty acids. The “Healthy Eating Plate” i), based on a nutritional survey, also promotes the intake of whole grains and favours the consumption of brown rice (BR) over that of polished rice.
Recently, germinated brown rice (GBR), which is produced by germinating BR for a few days, has been studied to find ways to make BR easier to eat. Germination also improves the absorption rate of nutrients and increases the content of γ-aminobutyric acid (GABA), which has been reported to be effective for metabolic syndrome (Goffman and Bergman, 2004), have mental stabilizing and antihypertensive effects (Abdou et al., 2006), and inhibitory effects on triglyceride level increases (Yoon et al., 2016). Until now, GBR has been studied as a form of BR for consumption as a staple food, but it can also be considered as BR in sprouted form. In recent years, sprouts grown for several days after germination have been found to contain more phytochemicals than conventionally grown plants (Goffman and Bergman, 2004), and their chemopreventive effects have attracted the interest of consumers (Fahey et al., 1997), leading to increased consumption. This has in turn led to active research worldwide on the development of novel methods for sprout cultivation and on the chemopreventive effects of sprouts.
However, no studies have been carried out to investigate GABA and amino acid contents after cultivating BR for more than 144 h. This may be because BR with the husk removed shows a rapid increase in starch-degrading enzyme activity with germination (Komatsuzaki et al., 2007; Palmiano and Juliano, 1973), and it easily decomposes when immersed in water for a long time, making it difficult to cultivate the sprouted form. On the other hand, juvenile rice grown to about 60 cm has a strong antioxidant effect and contains high levels of vitamin C and β-carotene, which are not contained in BR (Kumagai et al., 2004). Therefore, in this study, we aimed to establish a cultivation method for sprouted brown rice (SBR), in which the grain and bud could be consumed together by eating raw or after brief heating, in the same way as sprouts in general.
Currently, commercial sprouts are cultivated in plant factories with artificial light using various cultivation media and water. Slightly acidic electrolyzed water (SAEW) has been adopted as a promising form of cultivation water, and it has been reported to be effective for reducing microbial load, promoting the growth of GBR as well as increasing the GABA content in BR (Li et al., 2015; Liu et al., 2013). Therefore, we expected that using SAEW to cultivate SBR would be effective for reducing microbial load as well as increasing the content of GABA compared with cultivation with distilled water (DW).
To establish a cultivation method for SBR resulting in optimal morphology, we investigated the effects of culture medium and water type (SAEW or DW) on SBR morphology and amino acid contents. The amino acids investigated were classified into those related to palatability and those related to functionality, with a specific focus on GABA. We examined whether SBR grown by the newly developed method could be used as food with chemopreventive effects to help solve worldwide problems of lifestyle-related diseases.
Materials BR of the variety “Fukumaru”, harvested in Hitachiota, Ibaraki Prefecture in the autumn of 2018, was used for cultivating SBR. The 1000-grain weight of brown rice was 22.1 g. Two types of cultivation water were used: DW as a control and SAEW produced by a SAEW generator (PURESTER Muclean II; Morinaga Milk Industry Co., Ltd., Japan) for comparison. The available chlorine concentration (ACC) and pH of the SAEW were adjusted to 30 ± 6 ppm and pH 6.00 ± 0.20 using a handy water quality meter (AQUAB AQ-202 type; Shibata, Japan) and a pH meter (LAQUAact D-71; Horiba, Japan), respectively.
Washing and germination of BR BR grains were washed with SAEW at 20 °C before germination as follows. Into a wide-mouth polypropylene container with a cap (250 mL), 15 g of BR and 200 mL of SAEW (20 °C) were added and mixed at 50 rpm for 1 min. The SAEW was replaced, followed by mixing. The washed BR was placed in a glass petri dish (9.5 cm in diameter) with 100 mL of SAEW and allowed to germinate for 96 h in a germination box (Electronic fermenter SK-10; Taisyo, Japan) at 30 °C under natural light. The SAEW was changed every 24 h.
Comparison of SBR cultivated in different media The following media for BR sprouting were selected on the basis of previous research (Koyama and Hayashi, 2019; Kusano et al., 2001): urethane (height 2 cm, hydroponic leafy medium; Genuine Memory Store JP, Japan), conifer pulp (2.5 g, eco medium; Tagen Co., Ltd., Japan), sterilized rice husk (10.0 g; from the variety “ Fukumaru ” cultivated in Ibaraki, Japan), rice husk charcoal (10.0 g; Omiya Green Service Co., Ltd., Japan), and water (DW or SAEW, 100 mL). All media except for water were mixed with 50 mL of water and packed in a glass container of 7 cm length, 7 cm width, and 4 cm height so that the height of the medium containing water was 2 cm. Thirty GBR grains whose germination had been confirmed were set on each medium.
The SBR grains were cultivated in a plant growth incubator (V11-S01-RGB; MRT Co., Ltd., Japan) for 8 days. A 24-h cycle of light (12 h at 30 °C with white LED) and dark (12 h at 20 °C) periods was used and the water was changed once a day. The luminance of the LED was 352 µmol/m2 s, which was measured with a quantum sensor (Apogee MQ-200; Apogee Instruments, USA).
Independent experiments were performed three times with the 10 combinations of media and water (5 types of medium × DW or SAEW). Each cultivation was conducted with 30 grains in duplicate, and a total of 180 SBR grains were investigated for each combination. After cultivation, the bud length, dry weights (dw) of the root, grain, and bud, and amino acid contents were measured as described in the following sections.
Effect of water type (DW and SAEW) on cultivation of SBR The effects of cultivation water (DW and SAEW) on SBR grown with only water was investigated in detail. Three independent experiments were conducted, with each experiment consisting of triplicate sets of containers containing DW and SAEW. Each container held 30 GBR grains whose germination had been confirmed.
Investigation of SBR at different germination stages To investigate the optimum morphology for SBR, amino acid contents of SBR at various stages of germination were investigated. The cultivation medium used was SAEW, and the evaluation was carried out at the following five stages based on cultivation period: G0 (BR), G1 (germinated: bud length, 3 mm; 2–3 days of cultivation including the germination period), G2 (incomplete leaf: bud length, 5–15 mm; 4 days of cultivation), G3 (first leaf: bud length, 20–30 mm; 7 days of cultivation), G4 (second leaf: bud length, 40–70 mm; 14–19 days of cultivation).
Bud length and dry weight measurements of SBR The bud length of SBR was measured using a digital calliper. Each SBR was cut into its grain, bud, and root, which were then separately dried with a freeze dryer for 16 h and weighed with an electronic balance.
Determination of amino acid contents in BR and SBR The contents of 24 amino acids in BR and SBR were measured. The extraction procedure for amino acids followed that reported by Morita (2017). The dried grains, buds, and roots of BR and SBR after weighing were collected and crushed with a mill (Silent Millser IFM-S30G; Iwatani, Japan). A powdered sample (1.0 g) was mixed with 9 mL of 2 % sulfosalicylic acid solution (Special grade reagent; FUJIFILM Wako Pure Chemical Corporation, Japan) in a 50-mL plastic conical tube, and the mixture was shaken in a warm bath at 25 °C for 30 min. The mixture was centrifuged at 5 500 rpm for 10 min and the supernatant was filtered through a 0.45-µm filter to obtain the extract.
Amino acids were analysed using an automatic amino acid analyser (JLC-500/V2; JEOL Ltd., Japan). The post-column ninhydrin method was used with 50 µL of a sample in the high-resolution mode for free amino acids in lithium citrate buffer. The content of each amino acid was determined by comparing the peak area of the obtained sample with the peak area of the standard sample (amino acid mixed standard solution, AN-2 type and B type in equal amounts; FUJIFILM Wako Pure Chemical Corporation, Japan).
One measurement was carried out for each independent experiment, and the results of three measurements are shown as the average value per 100 g dw ± standard deviation.
Investigation of bacteria The viable cell counts of SBR before and after washing with running water (1 min) were investigated. SBR cultivated for 8 days using SAEW as the medium was used as the measurement sample. SBR samples (2.5 g) and 22.5 mL of sterilized 0.9 % physiological saline were placed in a sterilized stomacher bag (BAGMIXER 100 Mini Mix; Funakoshi Co., Ltd., Japan) and processed at level 6 for 90 s. For general viable count, coliform bacteria, and E. coli measurement, 1 mL of the supernatant was diluted with sterile 0.9 % saline, and 1 mL of the diluted solution was mounted on a Petrifilm (3M™AC plate, 3M™TME. coli/CC plate; 3M Japan Co., Ltd., Japan). To count spore-forming bacteria, the SBR after stomacher treatment was soaked in a water bath set at 70 °C for 20 min, and viable counts in the supernatant were measured with a Compact Dry test kit (Nisui Pharmaceutical Co., Ltd., Japan). All media were cultured at 35 °C for 48 h. The number of viable bacteria was expressed as log cfu/g. Three independent experiments were conducted.
Statistical processing The statistical analysis software SPSS version 25 (IBM) was used to determine the statistical significance of differences in bud length, sample weight, and amino acid content. Analysis of variance (ANOVA) was performed to select a test suitable for each parameter. The Tukey–Kramer test, t-test, and Kruskal-Wallis test were employed. The significance level for all tests was set at p < 0.05.
Effects of cultivation media and water type on morphology of SBR SBR was cultivated using DW or SAEW with five types of medium. Figure 1 shows images of the different media and the SBR grown in them, and Table 1 shows the lengths and weights of the bud, roots, and grain as the mean ± standard deviation per grain. Among the ten combinations of cultivation media and water type, rice husk charcoal with SAEW, DW only, and SAEW only showed significantly long buds compared with the other combinations, with average bud lengths of 39.3, 38.7, and 37.1 mm, respectively. Among these three, when only water was used, the SBR had almost no roots, and the weight of rice grains tended to be higher than that cultivated in the combination of rice husk charcoal and SAEW (10.0 and 9.9 mg/grain for DW and SAEW, respectively, as opposed to 8.3 mg/grain for rice husk charcoal). Since the roots of sprouts are generally not consumed, cultivation methods that lead to shorter roots of SBR are preferred. Suzuki (1999) also reported that anaerobic cultivation of BR resulted in a sprout form with short roots. The SBR cultivated in water not only showed short roots but also had the highest ratio of grains that had not self-digested.
Sprouting media (upper images) and sprouted brown rice (lower images)
8 days after transplantation. A: Water only, B: Rice husk charcoal, C: Pulp, D: Urethane, E: Rice husk
| Medium | Root | Grain | Sprout | Bud length | ||
|---|---|---|---|---|---|---|
| (Water type) | [mg/grain] | [mg/grain] | [mg/grain] | [mm] | ||
| Water (D) | 0.0 ± 0.0 | a | 10.0 ± 0.6 | 1.2 ± 0.4 | 38.7 ± 7.4 | a |
| Water (S) | 0.0 ± 0.1 | a | 9.9 ± 3.1 | 1.3 ± 0.2 | 37.1 ± 10.9 | ab |
| Rice husk charcoal (S) | 0.7 ± 0.1 | b | 8.3 ± 1.2 | 1.6 ± 0.1 | 39.3 ± 13.8 | b |
| Urethane (S) | 0.7 ± 0.7 | ab | 10.2 ± 2.5 | 1.8 ± 0.4 | 33.5 ± 10.5 | c |
| Rice husk (S) | 0.5 ± 0.3 | ab | 11.1 ± 2.0 | 1.8 ± 0.4 | 33.1 ± 13.6 | c |
| Rice husk charcoal (D) | 0.6 ± 0.3 | ab | 6.6 ± 2.8 | 1.5 ± 0.3 | 32.2 ± 6.5 | c |
| Urethane (D) | 0.2 ± 0.3 | ab | 8.5 ± 3.6 | 1.4 ± 0.1 | 32.1 ± 10.4 | c |
| Pulp (S) | 0.5 ± 0.2 | ab | 8.7 ± 2.3 | 1.8 ± 0.4 | 30.0 ± 6.4 | d |
| Pulp (D) | 0.5 ± 0.2 | ab | 7.6 ± 2.9 | 1.4 ± 0.4 | 28.5 ± 5.2 | de |
| Rice husk (D) | 0.3 ± 0.3 | ab | 9.2 ± 7.0 | 1.2 ± 0.1 | 25.5 ± 9.4 | e |
(D: distilled water, S: slightly acidic electrolyzed water) for 8 days cultivated after transplantation. Different letters indicate that means are significantly different (p<0.05, Bud length: Kruskal-Wallis, Root weigh, Grain weight, Sprout weight: Tukey-Kramer).
SBR cultivated in pulp and rice husk medium had a bad odour, which may be due to putrescine, a type of amine, produced by the decomposition of amino acids present in living or dead organisms and synthesized in small amounts by ornithine decarboxylase in healthy cells. Apart from the odour, the pulp, rice husk charcoal, and rice husk media became entangled with the SBR roots, which made them unsuitable for consumption. SBR cultivated in urethane medium tended to have thick, long roots, and mould frequently grew on the rice grains, which were not covered in water.
During germination, the embryos and aleurone layers break from dormancy with watering and heating, and amylase and protease are synthesized and secreted via gibberellin synthesis and signalling. These enzymes decompose starch and proteins that are stored in the endosperm adjacent to the scutellum and aleurone layers, the products of which are then used as carbon and nitrogen sources for the next generation of seedlings (Midorikawa et al., 2014). In this study, the weight of rice grains calculated from the 1000-grain weight (22.1 mg/grain, which can be converted to approximately 18.8 mg dw/grain by assuming a moisture content of 15 %) before treatment decreased to 10 mg dw/grain after cultivation. This decrease could be attributed to the starch consumption of rice grains due to germination and sprout growth. However, when the rice grain and buds are submerged in water, the respiratory activity of seedlings is lower than when aerobically germinated. This is due to differences in the spectra of mitochondrial cytochromes (Shibasaka and Tsuji, 1994). Therefore, submerging the buds as well as the grains of the SBR under water (as for the SBR grown with water only) was effective in preventing the decomposition of rice grains.
From these results, cultivation using only water (DW, SAEW) was most effective in the context of morphology. Next, the different media were compared in terms of amino acid contents, since increasing the contents of functional components is the main purpose of sprouting.
Effects of cultivation media and water type on amino acid content in SBR To examine the functionality of SBR as a food, the amino acid contents of BR and SBR were analysed, as shown in Fig. 2. The amino acids contained in germinated BR were evaluated by focusing on the secondary and tertiary functions, as well as the phenol-related function (antioxidant effects). The amino acids related to secondary functions include glutamic acid (Glu), threonine (Thr), serine (Ser), proline (Pro), glycine (Gly), and alanine (Ala) (Nishimura and Kato, 1988). Those related to tertiary functions include GABA, arginine (Arg), and β-aminoisobutyric acid (β-AIBA). Phenolrelated amino acids include phenylalanine (Phe) and tyrosine (Tyr). Amino acids that do not fall into any of the three categories above, namely, phosphoserine, taurine, aspartic acid, α-aminobutyric acid, valine, methionine, isoleucine, leucine, β-alanine, monoethanolamine, ornithine, histidine, and lysine were classified as “others”.
Amino acid contents (mg/100 g freeze-dried sample) of brown rice and sprouted brown rice cultivated in (A) slightly acidic electrolyzed water, and (B) distilled water with different medium for 8 days after transplantation. Different letters (A–total amino acid, a–b: GABA) indicate that means are significantly different (p < 0.05, Tukey–Kramer).
The BR variety Fukumaru used in this study has a large grain, and the weight of 1 000 Fukumaru grains is approximately 3 g heavier than that of Koshihikari. The large grain of Fukumaru has low amylose and protein contents as well as the physicochemical characteristics of a good-tasting rice (Nitta et al., 2014). The results of amino acid content measurement in this study show that Fukumaru BR contains higher levels (7.8 mg/100 g dw) of GABA than Koshihikari BR (3.8 mg/100 g dw, as reported by Saikusa et al., (1994)). Although Fukumaru is not a giant-embryo rice cultivar, its higher levels of GABA may be due to its large germ, even though it contains less protein than Koshihikari (Amai et al., 2015).
When BR germinated into SBR, the GABA and total amino acid contents increased considerably for all cultivation media. The GABA and total amino acid contents in SBR ranged from 44 to 284 mg/100 g dw and 334 to 719 mg/100 g dw, respectively, whereas those of BR were 7.8 and 35 mg/100 g dw, respectively. In particular, SBR cultivated with DW and SAEW showed significant increases in GABA and total amino acid contents compared with BR. The total amino acid contents of SBR cultivated with DW and SAEW were 719 and 631 mg/100 g dw, and the GABA contents of SBR cultivated with DW and SAEW were 284 and 215 mg/100 g dw, respectively.
Germination simultaneously initiates biosynthesis and degradation of amino acids in rice and causes large changes in the amino acid content (Yang et al., 2013). In addition, soaking induces the activity of glutamate decarboxylase (GAD) to catalyse the decarboxylation of L-glutamic acid to carbon dioxide and GABA (Komatsuzaki et al., 2008). Ohisa et al., (2003) reported a high correlation (R = 0.9258) between the free amino acid content and GABA content of GBR (Ohisa et al., 2003), and similar results were obtained in this experiment with a correlation coefficient of R = 0.9074.
The total amino acid and GABA contents of SBR cultured in media other than water tended to be lower than those of SBR cultured in water. Therefore, we concluded that media using only water was most suitable for the cultivation of SBR in terms of both morphology and amino acid contents.
Next, to determine the type of water, DW or SAEW, suitable for SBR culture, SBR grains were cultured in DW and SAEW simultaneously for 8 days. The amino acid contents of brown rice and sprouted rice are shown in Fig. 3. GABA and total amino acid contents were slightly higher in the SBR cultivated in SAEW, although the difference was not statistically significant. The GABA contents of SBR cultivated in DW and SAEW were 89 and 133 mg/100 g dw, and the total amino acid contents were 441 and 494 mg/100 g dw, respectively. In addition, the bud length was significantly larger for SBR cultivated in SAEW (37.3 mm) than that cultivated in DW (34.8 mm). These results show that SAEW has a positive effect on sprout growth. Based on these results, we determined that SAEW without any other media was optimal for cultivation.
Amino acid contents (mg/100 g freeze-dried sample) of sprouted brown rice cultivated for 8 days after transplantation using slightly acidic electrolyzed water (S) and distilled water (D) as medium. Values were not significantly different (GABA: p = 0.38, Total amino acid: p = 0.53, t-test).
Amino acid contents of SBR at different germination stages Finally, the optimum stage to consume SBR was evaluated in terms of GABA and amino acid contents. Figure 4 shows images of the SBR samples at stages from G0 to G4, and Fig. 5 shows the amino acid contents. Total amino acid contents tended to increase as the bud grew, and the total amino acid content at G4 (450 mg/100 g dw) was significantly higher than that at G0 (35 mg/100 g dw, 13 times higher on average).
Sprouted brown rice at different germination stages. G0: untreated, G1: 3 mm, G2: 5–15 mm, G3: 20–30 mm, G4: 40–70 mm. Amino acid contents (mg/100 g freeze-dried sample) of sprouted brown rice cultivated in slightly acidic electrolyzed water as medium.
Amino acid contents (mg/100 g freeze-dried sample) of sprouted brown rice cultivated in slightly acidic electrolyzed water as medium at five germination stages. Different letters (A-B: total amino acid) indicate that means are significantly different (p < 0.05, Tukey–Kramer).
The contents of GABA and tertiary function-related amino acids were highest at G3 (134 and 160 mg/100 g dw, respectively), although the values varied greatly between experiments, and there was no significant difference in contents among the different germination stages. Kamjijam et al., (2020) germinated rice with husk for 144 h and reported that the GABA content reached the maximum value of 31.36 mg/100 g dw after 96 h of cultivation at 34 °C. When Ecuadorian BR was germinated, the GABA content reached the maximum value (139.32 mg/100 g dw) when cultivated for 96 h at 34 °C (Cáceres et al., 2014). This study showed that the maximum levels were reached much later. The GABA content of SBR obtained in this study (134 mg/100 g dw) can be converted to per fresh weight (fw) as 42.2 mg/100 g fw. Ingestion of GABA at 30 mg per day is expected to show functional effects (Sasaki and Kouno, 2010). Calculated from the average GABA content observed in this study, 70 g fw of SBR would meet the daily intake requirements. However, continued investigation is needed to decrease the large variation observed between experiments in this study.
In this study, we also measured the content of β-AIBA, an isomer of GABA, and confirmed its increase during germination. To date, there have been a small number of reports of β-AIBA in foods. The content of β-AIBA in SBR cultivated by the method developed in this study is very low, but β-AIBA converts white adipocytes into brown adipocytes and enhances lipid metabolism. Therefore, it may be effective against lifestyle-related diseases (Roberts et al., 2014). Arg of SBR showed an increasing trend until the bud grew slightly (G2 stage), and then remained almost constant. Arg is known to affect endocrine secretion (Arvat et al., 1994), but the overall amount of Arg was not very high.
The contents of amino acids classified as related to phenols were highest at G3 (44 mg/100g dw) and were significantly higher than those at G0. One of the main pathways for biosynthesis is through phenylalanine–ammonia–lyase activity during germination, which binds acetyl-CoA and the amino acids via t-cinnamic acid, which are then reduced or are affected by enzymes to produce phenols. Ti et al., (2014) reported that during germination, the production of enzymes that degrade compounds around the cell wall significantly increases the contents of bound phenols and significantly increases the contents of free phenols. They also reported that the total phenol content reaches maximum at 30 h after germination. Our study showed that the maximum levels were reached much later, between G2 (4 days, 96 h) and G3 (7 days, 168 h), and the increase was observed over a longer period (168 h) than in previous studies. The difference may be due to the non-uniform growth among different grains.
The amino acids related to secondary functions (palatability) were highest at G4 (141 mg/100 g dw) and were significantly higher than those at G0. The SBR cultivated by the method developed in this study may have enhanced umami and sweetness due to increased Glu and Thr compared with GBR. Suzuki (1999) also reported that anaerobic underwater cultivation of BR leads to higher palatability. However, since the nutrients of rice grains are consumed as they grow, it is necessary to further investigate the nutrient components of SBR.
From the contents of amino acids, the optimal germination stage of SBR was determined to be between G3 and G4. These stages correspond to the seedling stage from the emergence of the first leaf to the emergence of the second leaf.
Viable count in washed SBR SBR cultured for 8 days using SAEW was used to measure viable counts. The SBR cultured for 8 days was a mixture of sprouts at the G3 and G4 stages. The general viable count and coliforms of SBR before washing were 7.6 and 3.2 log cfu/g, respectively, and no E. coli or spore-forming bacteria were detected. These values are comparable to the average viable cell count and coliform bacteria of sprouts in the market, which were reported as 6.08 and 3.41 log cfu/g, respectively ii). After washing, the general viable count of SBR was 2.9 log cfu/g, and no coliforms, E. coli or spore-forming bacteria were detected. These values satisfy the conditions for raw consumption (below 6.0 log cfu/g iii)), thereby confirming the hygienic safety of fresh SBR.
This study was conducted to increase the intake of whole grains by introducing a new form of BR consumption, SBR. By envisaging sprout cultivation in an artificial light-type plant factory, the optimum cultivation method was studied, and the findings are summarized as follows: (1) water (SAEW) was the optimal cultivation medium and the BR should be washed with SAEW at 20 °C before germination. Moreover, a transparent cultivation container that provides sufficient light was used in this study. (2) SBR seedlings without roots but with the first leaf (coleoptile) were found to be most suitable for consumption, which corresponded to a cultivation period between 7 and 14 days.
SBR cultivated from the variety Fukumaru contained a higher GABA content than that reported in previous studies. In addition, SBR may contain vitamin C and β-carotene in the leaves, which are not included in GBR. SBR can be consumed in a similar way to sprouts in general, and therefore is much quicker and easier to cook than BR and GBR. Investigation of general nutritional components should be conducted to characterize SBR in detail.
The materials, conditions, and equipment needed to cultivate SBR can be easily acquired. The production of rice crops is the third largest world-wide, while the cultivation method developed in this study is easy to use and produces little waste. Therefore, the SBR cultivation method developed in this research may effectively contribute to good health through the ingestion of whole grains and their chemopreventive effects.
Acknowledgements Dr. Tamaki Hirose of the Research Center of the University of Tsukuba provided technical assistance in amino acid analysis and Tagen Co., Ltd., provided the materials.
