Effect of some factors on the quality of black bean sprouts

Black bean sprouts are high in nutritional value with vitamins, minerals, amino acids, fiber, vitamin C and anthocyanin. The study was conducted as following: Black beans were soaked at temperatures of 25 °C, 30 oC, 35 oC, 40 oC and for period of 2 hours, 3 hours, 4 hours, 5 hours. The substrates were surveyed as ash, cotton towel, sand and paper tissue.

An Giang University Journal of Science – 2019, Vol 6, 70 – 79 EFFECT OF SOME FACTORS ON THE QUALITY OF BLACK BEAN SPROUTS Ho Thi Ngan Ha1 An Giang University Information: Received: 01/10/2017 Accepted: 02/12/2017 Published: 02/2019 Keywords: Black bean sprouts, soaking, substrate, sowing density, anthocyanin ABSTRACT Black bean sprouts are high in nutritional value with vitamins, minerals, amino acids, fiber, vitamin C and anthocyanin The study was conducted as following: Black beans were soaked at temperatures of 25 °C, 30 oC, 35 oC, 40 oC and for period of hours, hours, hours, hours The substrates were surveyed as ash, cotton towel, sand and paper tissue Seeds were sown at density of 25 seeds, 50 seeds, 75 seeds, 100 seeds in the same unit area of 60 cm2 The times of irrigation were investigated with once, twice, three times for the substrate in a day Finally, the study compared the differences in nutrients content of black bean sprouts and green bean sprouts as well as evaluated the sensory of two products The results of the study showed that: soaking black beans at 30oC for four hours gave the best germination ability The most suitable type of substrate was sand The appropriate sowing density was 75 seeds /60 cm2 The optimal number of irrigation every day was twice Nutrients content of black bean sprouts and green bean sprouts were as following: Moisture (82.2%, 86.4%), Protid (7.7%; 8.1%), total sugar (11.7%; 12.3%), vitamin C (34.10 mg%; 28.50 mg %), anthocyanin (6.8 mg/kg; 0mg/kg) The sensory evaluation result showed that black bean sprouts were more highly appreciated by consumers for structure and preference INTRODUCTION have not been studied In the world, Japan, USA, and EU countries have studied the germination of black bean and application it to the pharmaceutical field In addition to the basic nutrients, black bean sprouts also contain antioxidants (including anthocyanin, phenolic, flavonoid, saponin) that prevent cardiovascular disease and inhibit growth of cancer cells (such as liver cancer, breast cancer, prostate cancer, and colon cancer) (Daniel, Sergio & Janet, 2013) In addition, the current demand for safe vegetables is necessary for our country From the above reasons, the study investigated some factors that Bean sprout is a kind of vegetable that is found in many popular traditional foods in the world, especially in Asian countries like Vietnam, Japan, South Korea, Thailand, Malaysia, China and also well known in Western culinary culture Bean sprouts have nutrients such as essential amino acids, vitamins and minerals The process of producing bean sprouts is simple, at low cost, does not take much time In Vietnam, black bean quantity is quite large, and it can be produced to a variety of foods such as black bean powder, black bean milk, etc but black bean sprouts for food 70 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 affected the germination ability of black bean sprouts to create a new food product from black beans with nutrients and health benefits in order to meet the social demand The study also compared the content of some nutrients, especially anthocyanin, as well as the sensory properties of black bean sprouts with green bean sprouts to demonstrate the quality of black bean sprouts Statgraphics plus 5.0 with a significance test through LSD at the confidence level of 95% (P = 0.05) 2.3 The procedure for producing black bean sprouts Black beans were selected to remove unsavory seeds and washed with clean water to remove impurities and some microorganisms from the surface Seeds were soaked in washed water Then they were rinsed with clean water to remove acidic water on the surface Beans were drained before sowing to avoid the rot when planting After that, beans were sown on the substrate and kept at 30oC During incubation, the substrate was irrigated with water All samples are harvested after five days to identify the indicators MATERIALS AND METHODS 2.1 Materials - - - - Black beans: they were bought at Long Xuyen market, An Giang province New bean seeds were harvested for less than three months, dried, shiny black, smooth, non-damaged and had a uniform size Water: used domestic water attained to TCVN 5502-2003 for irrigation Substrates: • Sand: used raw black sand of construction to meet the TCVN 7570-2006 • Cotton towel: used a thin one having the size of (28x28) cm and weight of 25 g • Paper tissue: used a napkin • Ash: used ash from wood stoves and removed all impurities Chemicals were used for analysis: Diethyl ether, NaOH, HCl, Na2SO4, H2SO4, K2SO4, CuSO4, phenolphthalein, iodine, alcohol (China) They were supplied by Anh Vu Co (Ho Chi Minh City) Instruments: • Analytical balance (Ohus): accuracy 0.0001 g • Incubator (Memmert) • Spectrophotometer (SP1920) 2.4 Contents of study 2.4.1 Experiment 1: Investigation of effect of soaking temperature and period on germination ability The experiment was arranged randomly with two factors: - Factor A: Soaking temperature (oC) A1: 25 A3: 35 - A2: 30 A4: 40 Factor B: Soaking period (hours) B1 : B3 : B2 : B4 : Permanent parameters: - 2.2 Method of experimental layout and data processing Beans content: g (50 - 55 seeds) The ratio of beans to water for soaking: 1:30 Type of substrate: sand 200 g Sowing area: 60 cm2 Irrigation water content: each 30 ml, times/ day 2.4.2 Experiment 2: Investigation of effect of substrate types on germination ability The experiments were arranged randomly with the factors and three replications, indicated data was the mean value Collected data was graphed by using Microsoft Excel and statistically processed by the ANOVA analysis method using The experiment was arranged randomly with one factor: 71 Factor C: Substrate types An Giang University Journal of Science – 2019, Vol 6, 70 – 79 C1: Sand C2: Cotton towel C4: Ash C3: Paper tissue 2.4.4 Experiment 4: Investigation of effect of watering times on germination ability The experiment was arranged randomly with one factor: Permanent parameters: - Beans content: g (50 - 55 seeds) The ratio of beans to water for soaking: 1:30 Soaking temperature and period: optimal values selected from experiment The weight of substrates: sand 200 g, ash 200 g, cotton towel 100 g, paper tissue 50 g Sowing area: 60 cm2 Irrigation water content: each 30 ml, times/ day - E1: E3 : - The experiment was arranged randomly with one factor: - Factor D: Sowing density (seeds / 60 cm2) D1: 25 D3: 75 - The ratio of beans to water for soaking: 1:30 Soaking temperature and period: optimal values selected from experiment Type of substrate: optimal type selected from experiment Sowing density: optimal value selected from experiment Irrigation water content: each 30 ml 2.4.5 Comparison of differences in content of nutrients and sensory properties of black bean sprouts and green bean sprouts D2: 50 D4: 100 Permanent parameters: - E2: Permanent parameters: 2.4.3 Experiment 3: Investigation of effect of sowing density on germination ability - Factor E: Watering times (times / day) Black bean sprouts were produced with the optimal parameters in the above experiments, green bean sprouts were bought at Coopmart, Long Xuyen city, An Giang province Then analyzed content of some nutritional compositions and evaluated sensory properties of two types of sprouts The ratio of beans to water for soaking: 1:30 Soaking temperature and period: optimal values selected from experiment Type of substrate: optimal type selected from experiment Irrigation water content: each 30 ml, times/ day 2.5 Method of determining properties Table Methods of determining physical and chemical properties Property Method Weight Use an analytical balance (accuracy: 0.0001g) Length Use a ruler Moisture Drying method at 105 oC to constant weight (1) Protid Kjedahl method (1) Lipid Soxhlet method (1) Total sugar Lane-Eynon method (1) C vitamin Iodometric method (2) Anthocyanin pH differential method (3) Note: (1) Ha Duyen Tu (2009), (2) Tran Bich Lam (2006), (3) Lee, Durst and Wrolstad (2005) 72 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 Table Methods of evaluating sensory properties Property Method Color, taste, structure Method of scoring based a descriptive scale Preference Method of scoring based a Hedonic scale RESULTS AND DISCUSSION 3.1 Nutritional composition of black bean Table Nutritional composition of black bean (*) Ingredient Unit Content Moisture % 11.6 Lipid % 1.7 Total sugar % 49.3 Protid % 22.3 Anthocyanin mg/kg 68.4 Note: (*) Average result of three replications The results of Table show that black beans are very nutritious with Protid and total sugar content at 22.3% and 49.3%, respectively Besides, black beans also contain anthocyanin at 68.4 mg/kg The high nutrients’ content of seeds will contribute to the quality of bean sprouts germination When conditions of soaking are appropriate, the embryonic cells inside the bean can change dramatically, increase the volume, make the beans grow and germinate rapidly (Nguyen Huu Hoang & Luong Xuan Lam, 2010) Therefore, finding the optimal soaking temperature and period will facilitate the next stage of sprouts production The investigation results of the effect of soaking temperature and period on germination ability are presented in Tables 4, 5, 3.2 Effect of soaking temperature and period on germination ability Soaking process helps the beans absorb water, which in turn activates enzymes to stimulate seed Table Effect of soaking temperature on weight, length, germination percentage (*) Soaking (oC) temperature Weight (g) Length (cm) Germination (%) 25 15.3a 4.0a 48.4a 30 17.6c 4.4b 56.7b 35 17.3c 4.2ab 54.3b 40 16.2b 4.1a 50.3a F= 14.92 F= 4.43 F= 7.84 P= 0.0000 P= 0.0087 P= 0.0003 percentage Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level 73 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 From the data in Table 4, it is found that when soaking temperature is 25 oC; the results on weight, length and germination percentage are low because the temperature is too low, beans cannot swell at maximum, and water cannot penetrate inside the seeds, enzymes within the beans are not activated When the soaking at 40 °C, the high temperature inhibits the activity of the enzymes, slowing down the stimulation of the embryo to develop, so 40 ° C is not optimum When soaking seeds at 30 oC and 35 oC, the statistical results on weight, length, and germination percentage are the highest and not different statistically at 5% significance level because these temperatures are suitable for the penetration of water into bean cells, activating enzymes and stimulating embryos to germinate faster (Nguyen Huu Hoang and Luong Xuan Lam, 2010) Therefore, the temperatures of 30 °C and 35 °C are optimal, but 30 °C is close to ambient temperature, saving production costs Table Effect of soaking period on weight, length, germination percentage Soaking period (hours) Weight (g) Length (cm) Germination percentage (%) 15.0a 3.9a 45.6a 16.9b 4.2b 52.3b 17.6b 4.5c 57.4c 17.0b 4.2bc 54.3bc F= 17.61 F= 7.65 F= 14.14 P= 0.0000 P= 0.0004 P= 0.0000 Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level From the data in Table 5, the soaking period of two hours is not enough for water to penetrate the endosperm and stimulates germination When soaking seeds for longer periods, the seeds seize large amounts of water that cannot be released, reducing the aeration of seeds, thereby inhibiting the germination and development of embryos (Nguyen Huu Hoang and Luong Xuan Lam, 2010) Therefore, the optimal soaking periods for growth in weight, length and germination percentage are four hours and five hours However, economically, when soaking for four hours, it takes to shorten the time Table Effect of soaking temperature and period on weight, length, germination percentage Soaking temperature (oC) 25 30 Soaking period (hours) Weight (g) Length (cm) Germination rate (%) 13.7a 3.7a 41.7a 15.7bcd 3.9abc 48.7ab 16.3bcde 4.4cde 53.3bcde 15.7bcd 4.0abcd 50.0bc 15.5bc 3.9abc 48.3ab 17.4def 4.5de 51.7bcd 74 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 Soaking temperature (oC) 35 40 Soaking period (hours) Weight (g) Length (cm) Germination rate (%) 18.5f 4.7e 61.7f 18.5f 4.5de 58.0cdef 15.7bcd 3.9ab 46.3ab 17.3def 4.3bcde 51.3bcd 18.5f 4.5de 60.7ef 17.9ef 4.2abcde 58.6def 15.9ab 3.9abc 46.0ab 16.3bcde 4.0abcd 50.7bcd 17.0cdef 4.2abcde 54.0bcdef 16.5bcde 4.1abcd 50.7bcd F= 5.66 F= 2.32 F= 4.20 P= 0.0000 P= 0.0222 P= 0.0003 Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level Table is a statistical result of the interaction between soaking temperature and soaking period on weight, length and germination percentage This table shows that when soaking at 30 °C for hours, hours and 35 °C for hours, hours as well as 40 °C for hours, all three parameters of weight, length and germination percentage are highest and there are no significant differences at 5% significance level But economically, at high temperatures of 35 oC and 40 oC, it costs more to produce and when soaking for hours, it saves time Therefore, it can be concluded that the soaking seeds at 30 oC for hours are optimal Substrate is living environment for the beans to germinate and also where roots attach In the production of bean sprouts, the substrate has an important function of keeping moisture and providing it to the seeds for use in germination Beans themselves are full of nutrients for the embryos to develop, but without the proper moisture content, nutrients cannot be transformed Each beans type has a suitable substrate for sowing Therefore, finding the optimal substrate for black bean would contribute significantly to higher yields The results of study of effect of substrate types on germination ability of black beans are presented in Table 3.3 Effect of substrate types on germination ability Table Effect of substrate types on weight, length, germination percentage Types of substrate Weight (g) Length (cm) Germination percentage (%) Ash 14.7a 3.7a 44.7a Cotton towel 16.7ab 4.4ab 53.7b Sand 18.3bc 4.9bc 60.3bc 75 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 Types of substrate Weight (g) Length (cm) Germination percentage (%) Paper tissue 19.5c 5.2c 63.3c F= 6.05 F= 8.25 F= 10.63 P= 0.0187 P= 0.0079 P= 0.0037 Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level comparison to sand at 5% significance level Paper tissue has high moisture retention and softness, so it is easy for roots to penetrate as the graft for growth Sand also maintains moisture well, easily drained, and is recyclable material for subsequent production From the statistics in Table 7, types of substrate can affect the weight, length, and germination percentage of black beans sprouts - - - With ash, the product has the lowest weight, length and germination percentage Because the ash is difficult to drain, it limits the germination and growth of embryos (Le Xuan Hieu and Phan Thi Thao, 2011) With a cotton towel, the product has a higher germination percentage than the ash but compared with the paper towel All three parameters in weight, length and germination percentage are lower and statistically different at 5% significance level Cotton towel is widely used in growing because the ability to keep moisture is good and it is light, easy to find However, due to thick fabric, the roots are difficult to penetrate as the graft for growth With paper tissue, all weight, length and germination percentage are the highest but there are no statistically differences in From the above statistical results and in view of the application of industry production, sand was chosen as the substrate to carry out the next experiment 3.4 3Effect of sowing density on germination ability Density is the number of seeds sown per area unit Each type of beans has appropriate sowing density for high productivity Density is too much or too little that affect productivity Sowing density also affects the growth of bean sprouts So, finding appropriate sowing density would increase productivity and yield The results of the investigation of the effect of sowing density on germination ability are shown in Table Table Effect of sowing density on length, germination percentage Number of sown seeds (on an area of 60 cm2) Length (cm) Germination percentage (%) 25 5.8c 68.0b 50 5.4b 64.7a 75 5.3b 63.3a 100 4.6a 62.3a F= 15.85 F= 7.32 P= 0.001 P= 0.011 Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level 76 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 - - - When 25 seeds were sown on an area of 60 cm2, the sprouts length and germination percentage are the highest and statistically different from those of 50 seeds, 75 seeds and 100 seeds on the same area at 5% significance level Because at low sowing density, it creates aeration, promotes respiration, oxygen promotes enzyme activity, facilitates for metabolism of starch and other nutrients into simple nutrients that provide for the development of embryos (Nguyen Huu Hoang and Luong Xuan Lam, 2010) However, the sowing of seeds with too few seeds compared to the total surface area will cause wastage of substrates and area and not give high economic efficiency Sowing 100 seeds on an area of 60 cm2 give the lowest length and germination percentage Because sowing at too high density would reduce the aerobic capacity of a medium that causes hypoxia, thereby affecting the biochemical activity of the cell, preventing the formation of new agencies and the development of sprouts In addition, when sowing at high seed density, sprouts will compete for space and inhibit mutual development from length to weight (Nguyen Huu Hoang and Luong Xuan Lam, 2010) When 50 seeds and 75 seeds were sown on 60 cm2 area, length and germination percentage are relative high, and between two densities there is no statistical difference at 5% significance level Therefore, 50 seeds, 75 seeds are considered the most appropriate in the sprouts production, because the number of seeds suitable for the area of 60 cm2 that not cause to waste area, and the yield are more than of the density of 25 seeds / 60 cm2 But when it comes to economics, the density of 75 seeds per 60 cm2 is optimal because the more seeds are sown, the higher the yield Therefore, optimum density was 75 seeds / 60 cm2 3.5 Effect of watering times on germination ability Water is an important condition for stimulating and controlling the germination of bean sprouts Seeds germinate because of the absorption of water, water increases respiratory ability and catalyzes to break down complex organic matter into simple compounds, provide nutrients for the biochemical process (Nguyen Huu Hoang and Luong Xuan Lam, 2010) Each type of beans has different size, structure and chemical compositions, so it needs an appropriate amount of water for its growth and development The results of the survey on the effect of watering times on germination ability are presented in Table Table Effects of watering times on weight, length and germination percentage Watering times Weight (g) Length (cm) Germination percentage (%) once / day 25.0a 3.8a 47.8a twice / day 30.0b 4.9b 60.8b times / day 29.7b 5.0b 63.3b F= 28.64 F= 28.65 F= 37.40 P= 0.0000 P= 0.0000 P= 0.0000 Note: (*) The average result of three replications Data in the same column with the same letter are not statistically different at 5% significance level 77 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 The statistical results in Table show that, with the number of irrigations is once a day, the results are the lowest and there are statistically different at 5% significance level compared to twice and three times a day because there is not enough water to maintain moisture for the substrate throughout the day for germination When watering twice and three times a day, the results are the highest and there is no statistical difference at 5% significance level between them The watering many times in a day ensures to supply moisture regularly and maintain humidity for the substrate Therefore, the suitable watering time is twice a day, because this water content is enough to maintain the appropriate humidity for the substrate but without wasting water 3.6 Comparison of nutrients content and sensory properties of black bean sprouts and green bean sprouts 3.6.1 Comparison of nutrients content of black bean sprouts and green bean sprouts Table 10 Nutrients content of black bean sprouts and green bean sprouts (*) Ingredients Black bean sprouts a Green bean sprouts 86.4b Moisture (%) 82.2 Protid (%) 7.7a 8.1b Total sugar (%) 11.7a 12.3b Vitamin C (mg/ 100g) 34.1b 28.5a Anthocyanin (mg/kg) 6.8b 0a Note: (*) The average result of three replications The analytical results in Table 10 show that the production of black bean sprouts have great potential as the content of some nutrients in black bean sprouts is approximate to that of green bean sprouts (protein 7.7%; 8.1%, total sugar 11.7%; 12.3%), but the vitamin content was higher (34.1 mg%; 28.5 mg%) Especially, the black bean sprouts contain anthocyanin is 6.8 mg/kg which is not in the green bean sprouts Anthocyanin has antibacterial and antifungal activity; antioxidant activity; the ability to remove free radicals; the ability to remove heavy metals; the ability to absorb ultraviolet Many pharmacological functions of anthocyanin have been published: treating diabetes mellitus, visual ailments; maintaining vascular permeability; protecting blood vessels; protecting the liver Anthocyanin is effective in the treatment of heart disease, cancer, arthritis, strengthening blood vessels, nourishing the skin, producing histamine and preventing other diseases related to free radicals (Dang Thi Thu et al., 2009; Ahmed, Salih & Hadi, 2013) Therefore, in terms of nutritional value, black bean sprouts are also considered as nutritious and beneficial to human health 3.6.2 Comparison of sensory properties of black bean sprouts and green bean sprouts The black bean sprout is a new product that has not been yet available in the market, so through this sensory evaluation; researchers can collect information from the evaluator to see if their acceptance level for this new product Based on Chart 1, the sensory scores on color, taste, texture and preference of black bean sprouts are quite high In terms of color and taste, black bean sprouts have lower sensory scores than green bean sprouts The reason is that the color of black bean sprouts is not as bright as green bean sprouts And the first has sweet but slightly bitter taste and characteristic smell, so consumers might not be familiar In terms of structure, the green bean sprouts are characterized by porous and watery In contrast, black bean sprouts have a crispy structure creating a new feel for consumers, so consumers prefer black bean sprouts to green bean sprouts Similarly, black bean sprouts have a preference level of 8.4 higher than green bean sprouts Through the sensory evaluation of consumers, it can be concluded that black bean sprouts are 78 An Giang University Journal of Science – 2019, Vol 6, 70 – 79 highly appreciated by consumers, especially in terms of structure and preference Figure Sensory evaluation chart of black and green bean sprouts CONCLUSIONS AND RECOMMENDATION Daniel Guajardo-Flores., Sergio O SernaSaldívar., & Janet A Gutiérrez-Uribe (2013) Evaluation of the antioxidant and antiproliferative activities of extracted saponins and flavonols from germinated black beans Food Chemistry, 141, 1497–1503 4.1 Conclusions The germination ability of black bean sprouts was best under the following conditions: Soaking temperature and period were 30 oC, hours The substrate was sand Sowing density was 75 seeds / 60 cm2 Number of watering was twice a day Đang Thi Thu., To Kim Anh., Le Quang Hoa., Đo Ngọc Lien., Nguyen Thi Xuan Sam., Le Ngoc Tu & Đo Hoa Vien (2009) Biotechnology basis, Volume 2: Biochemical technology Vietnam: Education Publishing House Black bean sprouts had higher levels of anthocyanin and vitamin C than green bean sprouts The sensory evaluation result showed that black bean sprouts were more highly appreciated by consumers for structure and preference Ha Duyen Tu (2009) Chemistry analysis of food Hanoi: Science and Technology Publishing House Le Xuan Hieu & Phan Thị Thao (2011) Research on soybean sprouts production (Scientific research report) Lac Hong University, Ho Chi Minh, Viet Nam 4.2 Recommendations - Research on how to treat bean seeds to control pathogenic microorganisms that affect human health Investigate other types of substrates to produce high yield and quality, while ensuring safety Study the effect of harvesting time on the nutrients content with black bean sprouts Study the effect of package and temperature on the ability to preserve black bean sprouts Carry out a study on the production model of black bean sprouts in industrial scale Lee J., Durst R.W & Wrolstad R.E (2005) Determination of total monomeric anthocyanin pigment content of fruit juice, beverages, natural colorants and wines by the pH differential method: Collaborative study Journal of AOAC International, 88, 12691278 Nguyen Huu Hoang & Luong Xuan Lam (2010) Technicque to make bean sprouts Ho Chi Minh: Thoi Dai Publishing House REFERENCES Ahmed J.K., Salih H.A.M & Hadi A.G (2013) Anthocyanin in red beet juice act as scavenger for heavy metals ions such as lead and cadmium International Journal of Science and Technology, 2, 269-273 Tran Bich Lam (2006) Food Analysis Experiment Ho Chi Minh: National University Publishing House 79 ... nutrients content of black bean sprouts and green bean sprouts Table 10 Nutrients content of black bean sprouts and green bean sprouts (*) Ingredients Black bean sprouts a Green bean sprouts 86.4b... 68.4 mg/kg The high nutrients’ content of seeds will contribute to the quality of bean sprouts germination When conditions of soaking are appropriate, the embryonic cells inside the bean can change... demand The study also compared the content of some nutrients, especially anthocyanin, as well as the sensory properties of black bean sprouts with green bean sprouts to demonstrate the quality of black