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.

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EFFECT OF SOME FACTORS ON THE QUALITY OF BLACK BEAN SPROUTS

Ho Thi Ngan Ha1

1 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 2 hours, 3 hours, 4 hours, 5 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

1 INTRODUCTION

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

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

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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

2 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)

2.2 Method of experimental layout and data

processing

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

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

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 A2: 30

A3: 35 A4: 40

- Factor B: Soaking period (hours)

B1: 2 B2: 3

B3: 4 B4: 5 Permanent parameters:

- Beans content: 7 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, 3 times/ day

2.4.2 Experiment 2: Investigation of effect of substrate types on germination ability

The experiment was arranged randomly with one factor:

- Factor C: Substrate types

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C1: Sand C2: Cotton towel

C3: Paper tissue C4: Ash

Permanent parameters:

- Beans content: 7 g (50 - 55 seeds)

- Soaking temperature and period: optimal

values selected from experiment 1

- 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, 3 times/

day

2.4.3 Experiment 3: Investigation of effect of

sowing density on germination ability

The experiment was arranged randomly with

one factor:

- Factor D: Sowing density (seeds / 60 cm2)

D1: 25 D2: 50

D3: 75 D4: 100

Permanent parameters:

- Soaking temperature and period: optimal

values selected from experiment 1

- Type of substrate: optimal type selected from

experiment 2

- Irrigation water content: each 30 ml, 3 times/

day

2.4.4 Experiment 4: Investigation of effect of

watering times on germination ability

The experiment was arranged randomly with one factor:

- Factor E: Watering times (times / day)

E1: 1 E2: 2

E3: 3 Permanent parameters:

- Soaking temperature and period: optimal values selected from experiment 1

- Type of substrate: optimal type selected from experiment 2

- Sowing density: optimal value selected from experiment 3

- 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

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

2.5 Method of determining properties

Table 1 Methods of determining physical and chemical properties

Weight

Length

Moisture

Protid

Lipid

Total sugar

C vitamin

Anthocyanin

Use an analytical balance (accuracy: 0.0001g) Use a ruler

Drying method at 105 oC to constant weight (1) Kjedahl method (1)

Soxhlet method (1) Lane-Eynon method (1) Iodometric method (2)

pH differential method (3)

Note: (1) Ha Duyen Tu (2009), (2) Tran Bich Lam (2006), (3) Lee, Durst and Wrolstad (2005)

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Table 2 Methods of evaluating sensory properties

Color, taste, structure

Preference

Method of scoring based a descriptive scale Method of scoring based a Hedonic scale

3 RESULTS AND DISCUSSION

3.1 Nutritional composition of black bean

Table 3 Nutritional composition of black bean (*)

Moisture

Lipid

Total sugar

Protid

Anthocyanin

%

% mg/kg

11.6 1.7 49.3 22.3 68.4

Note: (*) Average result of three replications

The results of Table 3 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

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

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, 6

Table 4 Effect of soaking temperature on weight, length, germination percentage (*)

Soaking temperature

25

30

35

40

15.3a

17.6 c 17.3 c

16.2b

4.0a

4.4 b 4.2 ab

4.1a

48.4a

56.7 b 54.3 b

50.3a F= 14.92

P= 0.0000

F= 4.43 P= 0.0087

F= 7.84 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

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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 5 Effect of soaking period on weight, length, germination percentage

Soaking period

2

3

4

5

15.0a

16.9 b 17.6 b 17.0 b

3.9a 4.2b

4.5 c

4.2bc

45.6a 52.3b

57.4 c

54.3bc F= 17.61

P= 0.0000

F= 7.65 P= 0.0004

F= 14.14 P= 0.0000

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 6 Effect of soaking temperature and period on weight, length, germination percentage

( o C) Soaking period (hours) Weight (g) Length (cm) Germination rate (%)

25

2

3

4

5

13.7a 15.7bcd 16.3bcde 15.7bcd

3.7a 3.9abc

4.4 cde

4.0abcd

41.7a 48.7ab 53.3bcde 50.0bc

3

15.5bc

17.4 def

3.9abc

4.5 de

48.3ab 51.7bcd

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( o C) Soaking period (hours) Weight (g) Length (cm) Germination rate (%)

4

5

18.5 f 18.5 f

4.7 e 4.5 de

61.7 f 58.0 cdef

35

2

3

4

5

15.7bcd

17.3 def 18.5 f 17.9 ef

3.9ab

4.3 bcde 4.5 de 4.2 abcde

46.3ab 51.3bcd

60.7 ef 58.6 def

40

2

3

4

5

15.9ab 16.3bcde

17.0 cdef

16.5bcde

3.9abc 4.0abcd

4.2 abcde

4.1abcd

46.0ab 50.7bcd

54.0 bcdef

50.7bcd F= 5.66

P= 0.0000

F= 2.32 P= 0.0222

F= 4.20 P= 0.0003

Table 6 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 4

hours, 5 hours and 35 °C for 4 hours, 5 hours as

well as 40 °C for 4 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 4 hours, it saves

time Therefore, it can be concluded that the

soaking seeds at 30 oC for 4 hours are optimal

3.3 Effect of substrate types on germination

ability

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 7

Table 7 Effect of substrate types on weight, length, germination percentage

Types of substrate Weight (g) Length (cm) percentage (%) Germination

Ash

Cotton towel

Sand

14.7a 16.7ab

18.3 bc

3.7a 4.4ab

4.9 bc

44.7a 53.7b

60.3 bc

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Types of substrate Weight (g) Length (cm) percentage (%) Germination

F= 6.05 P= 0.0187

F= 8.25 P= 0.0079

F= 10.63 P= 0.0037

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

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 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 8

Table 8 Effect of sowing density on length, germination percentage

Number of sown seeds

25

50

75

100

5.8c

5.4 b 5.3 b

4.6a

68.0b

64.7 a 63.3 a

62.3a F= 15.85

P= 0.001

F= 7.32 P= 0.011

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- 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 9

Table 9 Effects of watering times on weight, length and germination percentage

once / day

twice / day

3 times / day

25.0a

30.0 b 29.7 b

3.8a

4.9 b 5.0 b

47.8a

60.8 b 63.3 b

F= 28.64 P= 0.0000

F= 28.65 P= 0.0000

F= 37.40 P= 0.0000

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The statistical results in Table 9 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 (*)

Moisture (%)

Protid (%)

Total sugar (%)

Vitamin C (mg/ 100g)

Anthocyanin (mg/kg)

82.2a 7.7a 11.7a 34.1b 6.8b

86.4b 8.1b 12.3b 28.5a

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

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highly appreciated by consumers, especially in terms of structure and preference

Figure 1 Sensory evaluation chart of black and green bean sprouts

4 CONCLUSIONS AND

RECOMMENDATION

4.1 Conclusions

The germination ability of black bean sprouts was

best under the following conditions: Soaking

temperature and period were 30 oC, 4 hours The

substrate was sand Sowing density was 75 seeds /

60 cm2 Number of watering was twice a day

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

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

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

Daniel Guajardo-Flores., Sergio O Serna-Saldívar., & 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

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

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

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,

1269-1278

Nguyen Huu Hoang & Luong Xuan Lam (2010)

Technicque to make bean sprouts 1 Ho Chi

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