Antinutritional factors and in vitro protein digestibilityof improved haricot bean (Phaseolus vulgaris L.)varieties grown in Ethiopia

EMIRE ADMASSU SHIMELIS & SUDIP KUMAR RAKSHIT

Food Engineering and Bioprocess Technology Program, Asian Institute of Technology, P. O. Box 4

Klong Luang, Pathumthani 12120, Bangkok, Thailand

AbstractThe antinutrient (raffinose oligosaccharides, tannins, phytic acid and trypsin inhibitors)composition and in vitro protein digestibility of eight improved varieties of Phaseolus vulgarisgrown in Ethiopia were determined. Stachyose was the predominant a-galactosides in all haricotbean samples. Raffinose was also present in significant quantities but verbascose, glucose andfructose were not detected at all in the samples. The concentrations observed for the proteindigestibility and antinutritional factors, varied significantly (P B/0.05) between varietiesinvestigated in this study. Mean values for protein digestibility ranged from 80.66% (in Robavariety) to 65.64% (in Beshbesh variety). Mean values for raffinose, stachyose, sucrose, trypsininhibitors, tannins and phytic acid were 3.14 mg/g, 14.86 mg/g, 24.22 mg/g, 20.68 TUI�/103/g,17.44 mg catechin equivalents/g and 20.54 mg/g, respectively. Statistical analyses of datarevealed that antinutritional factors and protein digestibility were influenced by variety(genotype). Relationships between antinutritional factors and protein digestibility were alsoobserved. The possibility of selecting varieties to be used for large-scale cultivation in Ethiopiaon the basis of these data is discussed. Among the improved varieties studied, Roba, Redwolaita,Mexican and Awash were found to be the best food and export type of haricot beans in theEthiopian context, because of their higher protein digestibility, lower antinutrtional factors andother beneficial nutritional parameters. Roba variety can be used by local food processors for theproduction of value-added bean-based products especially to combat the problem of proteinenergy malnutrition and related diseases which are very common in developing countries.

Keywords: Haricot bean, a-Galactosides, oligosaccharides, antinutritional factors, in vitro

protein digestibility, Ethiopia

Introduction

Food legumes have the exceptional, immediate potential for alleviating human

malnutrition in tropical countries by virtue of its nutritional and agronomic

advantages. The excellent nutritional value of most food legumes in terms of protein,

calories, vitamins, minerals, and fibers is highly complementary to a cereal-based diet

in developing countries. Most legumes have a distinct advantage over other food crops

because of their simplicity of preparation and multiplicity of edible forms (Salunkhe &

Kadam 1989). Haricot beans (Phaseolus vulgaris L.) are one of the food legumes

Correspondence: Emire Admassu Shimelis, Food Engineering and Bioprocess Technology Program, Asian

Institute of Technology, P. O. Box 4 Klong Luang, Pathumthani 12120, Bangkok, Thailand. Tel: �/66-2-

524-6215. Fax: �/66-2-524-6200. E-mail: Shimelis.Emire@ait.ac.th

ISSN 0963-7486 print/ISSN 1465-3478 online # 2005 Taylor & Francis

DOI: 10.1080/09637480500512930

International Journal of Food Sciences and Nutrition,

September 2005; 56(6): 377�/387

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which are good sources of nutrients and have a low glycemic index, ranging from

26�/42% relative to glucose (Foster-Powell & Miller 1995). However, like

other legumes, haricot beans can synthesize several undesirable chemical substances

termed antinutrients that are known to exert deleterious effects when ingested

by humans or animals. These substances include phytic acid (phytate), oligosacchar-

ides (flatulence producing factors), enzyme inhibitors and tannins, which can cause

adverse physiological responses or diminish the availability of certain nutrients

(Binyam et al. 1995).

A number of investigators have demonstrated that poor digestibility and biological

utilization of beans have been directly related to the antinutrients content of beans

which can hinder utilization of haricot beans for human nutrition and animal feed.

Among the antinutrients present in haricot bean seeds, phytate lowers the bioavail-

ability of certain minerals through formation of insoluble complexes at intestinal pH

(Erdman 1979). Oligosaccharides of the raffinose family of sugars (raffinose,

stachyose and verbascose) are known to produce flatus in human and animals. The

raffinose family of sugars remains unhydrolyzed due to the absence of a-galactosidase

enzyme activity which is capable of hydrolyzing the a-D-1-6 galactosidic linkage in the

small intestine and hence they are not absorbed (Fleming 1981). All the legumes

studied to date have been found to contain trypsin inhibitors in different amounts.

They have the ability to inhibit the action of the enzyme trypsin found in the digestive

tract of humans and animals (Bahnassey et al. 1986). Tannins are also known to be

present in food legumes and to inhibit the activities of trypsin, chymotrypsin,

amylase and lipase, decrease the protein quality (protein digestibility) of foods

and interfere with dietary iron absorption (De Lumen & Salamat 1980). Poor

digestibility and biological utilization of bean protein from cooked beans of the

colored cultivars have been directly related to the tannins content of these beans

(Elias et al. 1979). Protein quality in leguminous seeds does not reach the same

level as in animal products due to the low true digestibility of protein and the

presence of antinutritional factors in the seeds (Salunkhe & Kadam 1989). Therefore,

to utilize haricot beans as a more acceptable source of inexpensive protein and

carbohydrate, it is desirable to reduce/remove the flatulence producing factors and

some important antinutrients via plant breeding, biotechnological techniques and

processing technologies.

Most of the research on Ethiopian haricot beans has been related to varietal

selection. The criteria for selection have always been adaptation, resistant to disease,

rate of maturation, yields, seed size, color and specific agronomic traits, but never

nutritive quality. Information on the composition of antinutrients and protein

digestibility of improved haricot beans released from research centers was not

available at country level as a whole in the Ethiopian context (EARO 2001). This

information would therefore, be of great interest to Ethiopia because the knowledge

provided would help to orient the work of investigators involved in varietal selection,

gives base line information on the levels of unwanted components, and protein

digestibility which in turn evolves suitable, simple and inexpensive processing

techniques for the reduction/removal of those factors. Further more, as a result it

can boost the utilization of haricot bean varieties as value-added products at small-

scale industry level in the developing countries by local food processors.

The present study is aimed to evaluate the antinutritional factors, protein

digestibility and oligosaccharide contents of eight improved haricot bean varieties

378 E. A. Shimelis & S. K. Rakshit

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grown in Ethiopia. The results of this study can contribute to the intensive utilization

of haricot beans in the form of processed commercial products at industry level,

through large-scale cultivation of selected varieties.

Experimental materials

Source of materials, transportation and preparation

The improved haricot bean varieties used in this study were grown at Nazareth

Agricultural Research Center of Ethiopia. The varieties of Phaseolus vulgaris used for

this study were Roba, Mexican, Red Wolayita, Awash, Gofta, Beshbesh, Gobirasha

and Tabor. Haricot bean breeding seeds were transported by air to the food

engineering and bioprocess technology laboratory of the Asian Institute of Technology

(AIT), Bangkok. Samples were ground in analytical mill (Cole-Parmer, Cole-Parmer

Instrument Company, Model 4301-02, USA) and placed in plastic containers and

stored at room temperature (208C) before use. All chemicals and reagents used were

either analytical or reagent grade.

Experimental methods

Raffinose series oligosaccharides and other sugars

Extraction. Oligosaccharides were extracted from bean flour using a method of Agbo

et al. (1985).

Estimation by HPLC. The a-galactosides contents of extracted bean samples were

quantified by HPLC using the method of Doyon et al. (1991). ‘Hewlett-Packard

1100 series’ liquid chromatograph with analytical column (LiChrospher 100

NH2, 5 mm, 250�/4 mm, L�/ID, Hewlett Packard, Germany) and refractive index

detector were used for this study. Bean samples were eluted with acetonitrile/water

73:27 (v/v) as a mobile phase at a pump rate of 1 ml/min. All results of analyses were

expressed as mg/g.

In vitro protein digestibility experiment. Proteins from haricot beans were isolated for

protein digestibility analysis, using the m method of Satterlee et al. (1975). The

determination of in vitro protein digestibility of haricot bean varieties was carried out

using the method of Hsu et al. (1977).

Determination trypsin inhibitor activity. Trypsin inhibitor activity (TIA) in haricot bean

samples was measured according to the procedure of Kakade et al. (1974).

Tannins analysis. Tannins were assayed according to the Vanillin-HCl method of Price

et al. (1978).

Phytic acid analysis in haricot beans. Phytic acid content was evaluated using the

method of Haug and Lantzsch (1983).

Zinc and total ash composition. Total ash composition of the seed flour was performed

according to AOAC official methods 923.03, AOAC (2000). Zinc analysis was done

Antinutritional factors and protein digestibility of haricot bean varieties 379

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by the method reported by Issac and Johnson (1975), by atomic absorption

spectrophotometer.

Color measurement. Haricot beans were monitored for their surface and cotyledon

color by using color flex spectrocolorimeter, (Model no. 45/0, Hunter Lab Reston,

VA, USA, 2002) after being standardized using Hunter lab color standards. The

parameters recorded were L, a and b co-ordinates of the CIE scale.

Results and discussion

Oligosaccharides

The sugar contents of eight haricot bean varieties studied are presented in Table I.

Stachyose was the major a-galactosides contained in all the samples analyzed, which

also contained significant quantities of raffinose but verbascose was not detected at all

in the samples. Similarly, fructose and glucose were also not detected. Sucrose content

of haricot beans ranged from 17.27 mg/g (in Beshbesh) to 28.58 mg/g (in Mexican).

Raffinose concentrations ranged from 2.35 mg/g (in Awash) to 4.43 mg/g (in

Gobirasha) and stachyose concentrations from 12.38 mg/g (in Roba) to 18.41 mg/g

(in Beshbesh). Similar concentrations of raffinose, stachyose and sucrose have been

reported for haricot beans grown in Canada (Sosulski et al. 1982) and in Burundi

(Barampama & Simard 1993). However, some investigators (Agbo 1982; Sathe et al.

1983; Reddy et al. 1984; Salunkhe & Kadam 1989; Burbano et al. 1999), who assayed

haricot bean varieties grown in the USA for flatus factor, have observed raffinose

(2�/10 mg/g) and stachyose (2�/56.2 mg/g) concentrations higher than those obtained

for haricot bean varieties grown in Ethiopia and used in our study. Similarly, for

haricot bean varieties grown in different Spanish areas, flatus factors were reported as

0.9�/5.6 mg/g raffinose, 18.3�/29.3 mg/g stachyose, 0.4�/2.7 mg/g verbascose and

12.8�/28.9 mg/g sucrose (Burbano et al. 1999; Muzquiz et al. 1999). However,

cultivars of Phaseolus vulgaris grown in Brazil (Trugo et al. 1990) have observed

raffinose (0.5�/1.4 mg/g), stachyose (3.2�/4.7 mg/g) and sucrose (3.0�/3.7 mg/g).

These values are lower compared to the bean analyzed in the present study. In

Table I. Composition of raffinose, stachyose, sucrose, total a-galactosides and oligosaccharides expressed as

(mg/g) in haricot bean varieties.

Varieties Stachyose Raffinose Total a-galactosides Sucrose Total oligosaccharides*

Roba 12.389/0.01e 3.369/0.07b 15.749/0.04e 26.849/0.01b 42.589/0.03c

Gobirasha 14.169/0.04c 4.439/0.05a 18.599/0.05c 23.449/0.02e 42.039/0.04c

Beshbesh 18.419/0.07a 2.899/0.01c 21.309/0.04a 17.279/0.01g 38.579/0.03d

Gofta 14.199/0.01c 4.349/0.00a 18.539/0.01c 24.059/0.03d 42.589/0.02c

Awash 16.679/0.06b 2.359/0.03e 19.029/0.05b 25.249/0.01c 44.269/0.03b

Mexican 16.319/0.02b 2.829/0.03c 19.139/0.03b 28.589/0.07a 47.719/0.05a

Redwolaita 13.039/0.01d 2.489/0.08d 15.519/0.05e 28.189/0.01a 43.699/0.03b

Tabor 13.399/0.05d 2.409/0.00d 16.099/0.03d 20.169/0.08f 36.259/0.06e

All values are the mean9/SD of triplicates analysis and expressed in dry weight basis.a � gMeans with different superscript letters within a column indicate statistically significant differences

(P B/0.05).

*Total oligosaccharides (mg/g)�/Total a-galactosides (mg/g)�/Sucrose (mg/g).

380 E. A. Shimelis & S. K. Rakshit

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general, all the comparisons indicate that concentration of oligosaccharides varies

depending on location of growth and variety (genotype) used.

In vitro protein digestibility

In vitro protein digestibility of haricot bean varieties studied revealed significant

differences (P B/0.05). The in vitro protein digestibility varied from 65.64% (in

Beshbesh) to 80.66% (in Roba). The obtained results are similar to those

reported (66.9�/70.9%) by Deshpande et al. (1984b) for haricot bean varieties grown

in the USA, Barampama and Simard (1993) for haricot bean varieties grown in

Burundi, Vadivel and Janardhanan (2000) for velvet bean varieties grown in South

India. Similarly, lower values for protein digestibility (36.3�/56.0%) have been

also reported by Salunkhe and Kadam (1989) for different haricot bean varieties.

Reports from many investigators on protein digestibly of food legumes indicated that

bean protein digestibility is influenced by genotype, environmental and varietal

interaction.

In general, factors influencing the nutritional quality of haricot bean proteins

include the amino acid pattern and degree of digestibility, as well as the quantity and

quality of the other food proteins consumed along with the dry bean proteins. In this

study significant negative correlation was detected between some antinutrients such as

stachyose, a-galactosides, tannins, trypsin inhibitors and in vitro protein digestibility.

Protein digestibility had significant positive correlation with sucrose of dry beans

(Table III).

The obtained result from our study indicates that, higher in vitro protein

digestibility of Roba (80.66%) supports the popularity and acceptability of

this variety by the consumers among the dozen released varieties of haricot

bean from research centers of Ethiopia. The result of protein digestibility for

Roba variety is in agreement with the previous report in proximate composition

and physico-chemical properties of dry bean varieties grown in Ethiopia (Shimelis &

Rakshit 2005). Redwolaita also has 77.44% digestibility next to Roba varieties.

The higher protein digestibility and preferred color qualities makes them

more acceptable to the farming households and used as a cheap source of protein

Table II. Protein digestibility (%) and antinutritional factor (expressed as mg/g for tannins and phytic acid,

TUI1/mg for trypsin inhibitor) of haricot bean varieties.

Varieties Trypsin inhibitors Tannins Phytic acid Protein digestibility

Roba 4.599/0.02h 5.389/0.01g 23.519/0.12b 80.669/0.03a

Gobirasha 27.259/0.07b 23.559/0.01b 22.949/0.09c 68.879/0.07g

Beshbesh 29.279/0.09a 28.799/0.14a 17.349/0.10g 65.649/0.04h

Gofta 24.099/0.06c 19.699/0.01c 20.099/0.07e 69.369/0.01f

Awash 20.899/0.05e 17.569/0.08d 24.079/0.09a 71.159/0.02e

Mexican 21.449/0.08d 17.699/0.06d 16.819/0.02h 72.339/0.05d

Redwolaita 17.979/0.04g 11.159/0.01f 18.279/0.05f 77.449/0.01b

Tabor 19.949/0.01f 15.689/0.09e 21.279/0.01d 73.579/0.02c

1Trypsin units inhibited. All values are means of three replicate analyses9/SD and expressed in dry weight

basis.a �hMeans with different superscript letters within a column indicate statistically significant differences

(P B/0.05).

Antinutritional factors and protein digestibility of haricot bean varieties 381

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for most of the rural households who can not afford to buy expensive animal meat for

protein.

Trypsin Inhibitor Activity (TIA)

Trypsin inhibitor activities of the haricot bean varieties studied are given in Table II.

Gobirasha and Beshbesh varieties had higher values (27.25 and 29.27) TUI/mg,

respectively, while Roba had the lowest (4.59) TUI/mg. There was significant

difference (P B/0.05) between them. The variations in the activity of the trypsin

inhibitor (4.59�/29.27 TUI/mg sample, dry basis) between the different varieties of

Phaseolus vulgaris presented in this work are in agreement with variations for trypsin

inhibitors determined in other haricot bean varieties grown in different countries

(12�/20 TUI/mg, Sosulski et al. 1982; 4.77�/27.89 TUI/mg, Barampama & Simard

1993). Compared to obtained results, higher concentrations have been reported for

trypsin inhibitors determined in other varieties and species of legumes (Mancini &

Lajolo 1981; Thorn et al. 1983; Khokhar & Chauhan 1986; Trugo et al. 1990). A

significant negative correlation between trypsin inhibitor and protein digestibility

similar to our study has been reported by many investigators including Kakade and

Evans (1965); Hernandez-Infante et al. (1979); Furuichi et al. (1988); Barampama

and Simard (1993).

The negative relation which exists between trypsin inhibitor and protein digestibility

reduces the nutritive protein quality in haricot beans. This is corroborated by the

variety Roba, which had the lowest TUI/mg among the varieties studied in this work

and the corresponding higher protein digestibility. This perhaps makes it popular at

household level and small commercial food vendors in Ethiopia. On the other hand,

Beshbesh had the highest TIA and the lowest protein digestibility (protein quality)

thus making it less acceptable to the consumers. Food technologists, nutritionists,

Table III. Relations between in vitro protein digestibility and antinutritinal factors in haricot beans.

Relation Correlation coefficient Significance of correlationa

Protein digestibility�/Trypsin inhibitor �/0.939 �/�/�/

Protein digestibility�/Tannins �/0.983 �/�/�/

Protein digestibility�/Phytic acid 0.251 �/

Trypsin inhibitor�/Phytate �/0.383 �/

Phytate�/Tannins �/0.322 �/

Tannins�/Trypsin inhibitor 0.949 �/�/�/

Protein digestibility�/a-galactosides �/0.885 �/�/�/

Raffinose�/Protein digestibility �/0.278 �/

Stachyose�/Protein digestibility �/0.757 �/�/�/

Sucrose�/Protein digestibility 0.643 �/�/�/

Stachyose�/a-galactosides 0.916 �/�/�/

Stachyose�/Raffinose �/0.244 �/

Stachyose�/Sucrose �/0.438 �/

a-Galactosides�/Raffinose 0.165 �/

a-Galactosides�/Sucrose �/0.458 �/

Phytic acid�/Ash 0.964 �/�/�/

Zinc�/Phytic acid �/0.487 �/

Ash�/Zinc �/0.408 �/

a �/�/�/Highly significant (P B/0.001); �/Significant (0.01B/P B/0.05); �/not significant (P �/0.05).

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economists, agronomist and plant breeders must make joint efforts in releasing bean

varieties with lower TIA (higher digestibility), better protein quality and bioavailability

of nutrients which in turn makes the varieties more acceptable to producers, agro-

processing industries and consumers.

Tannins

Tannins concentration ranged from 5.38 (in Roba) to 28.79 mg catechin equivalent/g

(in Beshbesh) and significant differences (P B/0.05) among varieties were observed.

The result of the study is consistent with those mentioned by previous workers for

haricot bean varieties grown in other countries, tannins (0.3�/29.3 mg catechin

equivalent/g); (Sathe et al. 1983; Aw & Swanson 1985). Deshpande and Cheryan

(1983) and Reddy et al. (1985) have observed, for haricot bean varieties grown in the

USA, lower tannins concentrations (0.34�/26.5 mg catechin equivalent/g) than those

obtained in our study. Barampama and Simard (1993) have also reported for haricot

beans grown in Burundi with a wider range of tannins concentration (0.11 to

28.78 mg/g). There were significance differences in the surface color of the eight

varieties of dry beans. Tannins concentration is influenced by the color of the haricot

bean seeds. All color parameters of the L, a and b co-ordinates of the CIE scale are

correlated with tannins. Colored bean seeds (Table IV), Beshbesh and Gobirasha

varieties indeed presented higher tannins concentrations than the other bean seeds

studied (Table II). This observation is in agreement with the findings given by Sotelo

and Hernandez (1980) that correlate concentration of tannins in bean varieties with

their color value for bean varieties grown in the USA.

A highly significant negative correlation between tannins concentration and protein

digestibility has also been reported by Sosulski et al. (1982) and Aw & Swanson

(1985). In the present study, a negative correlation was observed between tannins and

protein digestibility of haricot beans (Table III). Although, white and light creamy

beans would be preferred from a protein digestibility point of view, it is not the only

basis for purchase of such products from Ethiopia.

Table IV. Color analysis of haricot beans.

Seed color1

Varieties Bean testa color L a b

Roba Creamy 58.549/0.10d 6.499/0.08e 25.399/0.13a*

Gobirasha Red 30.309/0.19f 12.579/0.11b 5.879/0.24g

Beshbesh Mottled 61.689/0.25c 7.519/0.12d 17.779/0.203d

Gofta Beige 55.739/0.39e 8.199/0.11c 22.509/0.19b

Awash White 69.349/0.55b 2.189/0.06f 13.319/0.19e

Mexican White 73.949/0.20a* 1.699/0.06f 11.089/0.35f

Redwolaita Red 28.829/0.64g 14.399/0.09a* 5.719/0.62g

Tabor Creamy 57.489/0.29d 8.659/0.15c 18.419/0.28c

1L-lightness (black/white), a-chroma (green/red) and b-hue (blue/yellow). All values are means of

triplicates9/standard deviation. a* � gMeans with different superscript letters within a column indicate

statistically significant differences (P B/0.05).

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Phytic acid

Beans, like many other seeds, contain a major portion of phosphorus as phytate

phosphorus (Pphytate). Phytate reduces the bioavailability of minerals, and the

solubility, functionality and digestibility of protein and carbohydrate (Reddy et al.

1982). The phytate ion complexes with di- and trivalent metallic ions (Zn�2, Ca�2,

Mg�2, Fe�2, Fe�3) and in many cases it forms insoluble compounds. Zinc forms the

most stable complex with phytic acid in the physiological pH ranges and reduces the

amount of phosphorus and associated metal ion available for absorption in the

intestinal tract of an animal (Lolas & Markakis 1975). Phytic acid, which is major

phosphorus storage of haricot bean varieties studied, is presented in Table II. It varied

among the eight varieties of haricot bean from 16.81 to 24.07 mg/g, the highest being

in Awash and the lowest in Mexican. The analysis of variance (ANOVA) indicated that

phytic acid mean difference was significant at 0.05 levels. Deshpande and Cheryan

(1983) have reported for haricot bean varieties grown in the USA with concentration

of phytic acid ranged from 18.1 to 27.5 mg/g, and Barampama and Simard (1993)

reported for haricot beans grown in Burundi ranged from 12.37 to 23.60 mg/g.

Comparable findings were observed in our study. However, Muzquiz et al. (1999)

reported that 3.10�/5.01 mg/g phytate was observed for haricot bean varieties grown in

different areas of Spain, and these are lower compared to our and others reported

values.

Zinc concentrations in the eight varieties of haricot bean studied, is presented in

Table V, varied from a low of 15.39 mg/kg (in Tabor) to 28.22 mg/kg (in Redwolaita).

Numerous investigators, beginning with O’Dell and Savage (1960) to Lonnerdal

(2002), have suggested that phytic acid may be responsible for reduced zinc

availability. Results had shown that a significant positive correlation (Table III)

between ash and phytic acid concentration was existent. The result of this study also

confirms that, phytic acid and zinc have a significant negative correlation. Zinc is an

essential trace element (micronutrient) involved in the immune function, in the

activation of many enzymes, normal healthy growth and reproduction. Therefore,

zinco-protein supplementation of formulated bean-based foods can reduce protein

energy malnutrition (PEM) disease and diminishes the zinc deficiency in foods which

is a seriously limiting factor in Africa and Asia.

Table V. Zinc composition (mg/kg) and ash (g/100g) contents of haricot bean varieties.

Varieties Zinc Total Ash

Roba 15.999/0.00e 3.939/0.01b

Gobirasha 23.919/0.16c 3.879/0.00b

Beshbesh 28.039/0.22a 3.229/0.01d

Gofta 27.609/0.13b 3.369/0.00d

Awash 17.219/0.23d 4.269/0.16a

Mexican 17.919/0.16d 2.869/0.00e

Redwolaita 28.229/0.00a 3.279/0.00d

Tabor 15.399/0.01e 3.529/0.00c

All values are means of triplicates9/standard deviation in dry weight basis.a � fMeans with different superscript letters within a column indicate statistically significant differences

(P B/0.05).

384 E. A. Shimelis & S. K. Rakshit

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Conclusions

Quantitative differences in the concentrations of the antinutrients, saccharides and in

vitro protein digestibility of eight improved haricot bean varieties were evident.

Genetic variability is the predominant factor for the observed variability in the

contents of these components. In the present study, correlation was observed between

in vitro protein digestibility, trypsin inhibitors, tannins, a-galactosides, sucrose, phytic

acid, zinc and ash for the dry bean varieties analyzed. The results also revealed some

correlations between the antinutritional factors investigated.

From a nutritional point of view, these results would help investigators to select dry

bean varieties with reduced levels of antinutritional factors for human consumption

and large-scale cultivation. Roba was found to be the best variety in terms of higher in

vitro protein digestibility, lower flatulence-causing factors, tannins and trypsin

inhibitors. Thus, Roba can be used as a potential raw material in food processing

industry for the production of bean flour or grits, weaning mixtures and supplemen-

tary bean-based processed foods including fortified and culinary products that are

affordable for most of the consumers.

The influence of locality and interaction of variety�/locality on haricot bean

composition, protein quality and antinutritional factor concentrations in haricot

beans needs further investigation for making appropriate choices to utilize effectively

their potential as human food as well as for animal feed production through large-scale

cultivation.

Integration of nutritional priorities within agricultural research programs need

consideration, and equal attention must be accorded to the selection of genotypes

(new cultivars) that meet consumer criteria in terms of high nutrient content,

preferred color, required grain size, higher digestibility with less flatulence factors and

low antinutritonal compounds. Therefore, stimulated interaction is needed between

scientists in the agronomic and genetic fields, nutritionists, food technologists, policy

makers, NGOs and private sectors (investors) in order to demonstrate the true

meaning of crop and food improvement for the benefit of subsistence farmers,

consumers and other stakeholders especially in developing countries like Ethiopia.

Acknowledgements

The authors are grateful for support from National Food Institute (NFI) of Thailand,

Laboratory Services Department, the Ethiopian Agricultural Research Organization

(EARO, Addis Ababa) and the Asian Institute of Technology (AIT, Bangkok). The

first author wishes to thank Bernice Buot Polohan and Vivek Sharma for their support

during the course of the experimentation and manuscript preparation.

References

Agbo NG, Uebersax MA, Hosfield GL. 1985. Efficient extraction techniques of sugars from dry edible

beans (Phaseolus vulgaris L.) and estimation of HPLC.Ann.Univ. Nation de Cote d’Ivoire, Se?rie C

(Sciences) , tome XXI-B:167�/187.

Agbo NG. 1982. Genetic, physico-chemical & structural parameters affecting texture of dry edible beans.

Ph.D thesis. Michican State University, USA.

AOAC. 2000. Association of Official Analytical Chemists (AOAC). Official methods of analysis of the

association of official analytical chemists: Food composition; additives; natural contaminants. In: William

H, (editor). Volume II, 17th ed. Washington DC: Association of Official Analytical Chemists. official

method 982.14.

Antinutritional factors and protein digestibility of haricot bean varieties 385

Int J

Foo

d Sc

i Nut

r D

ownl

oade

d fr

om in

form

ahea

lthca

re.c

om b

y U

nive

rsity

of

Sout

hern

Cal

ifor

nia

on 0

4/09

/14

For

pers

onal

use

onl

y.

Aw TL, Swanson BG. 1985. Influence of tannins on Phaseolus vulgaris protein digestibility and quality. J

Food Sci 50:67�/71.

Bahnassey Y, Khan K, Harrold R. 1986. Fortification of spaghetti with edible legumes. I. Physicochemical,

antinutritional, amino acid, and mineral composition. Cereal Chem 63:210�/215.

Barampama Z, Simard ER. 1993. Nutrient composition, protein quality and antinutritional factors of some

varieties of haricot beans (Phaseolus vulgaris, L.) grown in Burundi. Food Chem 47:159�/167.

Binyam K, Kelbessa U, Ayele N. 1995. Effect of processing methods on the trypsin inhibitor, tannins, phytic

acid and ODAP contents of grass pea seeds. Ethiopian J Health Dev 9:97�/103.

Burbano C, Muzquiz M, Ayet G, Cuadrado C, Pedrosa M. 1999. Evaluation of antinutritional factors of

selected varieties of Phaseolus vulgaris . J Sci Food Agric 79:1468�/1472.

De Lumen BO, Salamat LA. 1980. TIA in winged beans (Psophocarpus tetragnolobus ) and the possible role of

tannins. J Agric Food Chem 28:533�/536.

Deshpande SS, Sathe SK, Salunkhe DK. 1984b. Haricot beans of Phaseolus : A review. Part 3. Crit Rev

Food Sci Nutr 21:137�/195.

Deshpande SS, Cheryan M. 1983. Changes in phytic acid, tannins and trypsin inhibitory activity on soaking

of haricot bean (Phaseolus vulgaris ). Nutr Rep Int 27:371�/377.

Doyon G, Gaudreau G, St-Gelais D, Beaulieu Y, Randall JC. 1991. Simultaneous HPLC Determination of

Organic Acids, Sugars and Alcohols. Canadian Institut Sci Technol J 24:87�/94.

Ethiopian Agricultural Organization (EARO). 2001. Food science and post harvest technology research

program strategy. Addis Ababa, Ethiopia: Ethiopian Agricultural Organization (EARO).

Elias LG, DeFernandez DG, Bressani R. 1979. Possible effects of seed coat polyphenolics on the nutritional

quality of bean products. J Food Sci 44:524.

Erdman JW. 1979. Oilseed phytates: Nutritional implications. J Oil Chem Soc 56:736�/741.

Fleming SE. 1981. A study of relationships between flatus potential and carbohydrate distribution in legume

seeds. J Food Sci 46:794�/798, 803.

Foster-Powell K, Miller JB. 1995. International tables of glycemic index. Am J Clin Nutr 62:5871�/5890.

Furuichi Y, Sawada M, Takahashi T. 1988. Antinutritional factors in tora-mame seeds on the Japanese

cultivars of Phaseolus vulgaris . Nutr Rep Int 37:713�/722.

Haug W, Lantzsch HJ. 1983. A sensitive method for the rapid determination of phytate in cereals and cereal

products. J Sci Agric 34:1423�/1426.

Hernandez-Infante M, Herrador-Rena G, Sotelo-Lopez A. 1979. Nutritive value of different beans

(Phaseolus vulgaris ) supplemented with methionine. J Agric Food Chem 27:965�/968.

Hsu HW, Vavak DL, Satterlee LD, Miller GA. 1977. A multienzyme technique for estimating protein

digestibility. J Food Sci 42:1269�/1273.

Issac RA, Johnson WC. 1975. Collaborative study of wet and dry ashing techniques for elemental ananlysis

of plant tissue by Atomic Absorption Spectrophotometer. J Assoc Anal Chem 58:436�/440.

Kakade ML, Evans RJ. 1965. Nutritive value of navy beans. Brit J Nutr 19:269�/276.

Kakade ML, Rackis JJ, McGhee JE, Pusk G. 1974. Determination of trypsin inhibitor activity of soy

products: A collaborative analysis of an improved procedure. Cereal Chemistry 51:376�/382.

Khokhar S, Chauhan BM. 1986. Antinutritional factors in moth bean (Vigna aconitifolia ): Varietal

differences and effects of methods of domestic processing and cooking. J Food Sci 51:591�/594.

Lolas GM, Merkakis P. 1975. Phytic acid and other phosphorus compounds of beans (Phaseolus vulgaris L.).

J Agric Food Chem 23:13.

Lonnerdal B. 2002. Phytic acid-trace element (Zn, Cu, Mn) interactions. Int J Food Sci Technol 37:749�/

758.

Mancini FJ, Lajolo FM. 1981. Fatores antinutricionais em diferentes variedades de feijoes. Ciencia e

Cultura 33:94�/98.

Muzquiz M, Burbano C, Ayet G, Pedrosa MM. 1999. The investigation of antinutritional factors in

Phaseolus vulgaris . Environmental and varietal differences. Biotechnol Agro, Social Environ 4:210�/216.

O’ Dell BL, Savage JE. 1960. Effect of phytic acid on zinc bioavailability. Proceedings of the society for

experimental biology and medicine 103:304�/306.

Price ML, Van Scoyoc S, Buttler LG. 1978. A critical evaluation of vanillin reaction as an assay for tannins

in sorghum grain. J Agric Food Chem 26:1214�/1218.

Reddy NR, Sathe SK, Salunkhe DK. 1982. Phytate in legumes and cereals. Adv Food Res 28:1�/92.

Reddy NR, Pierson MD, Sathe SK, Salunke DK. 1984. Chemical, nutritional and physiological aspects of

haricot bean carbohydrates. A review. Food Chem 13:25�/68.

Reddy NR, Pierson MD, Sathe SK, Salunkhe DK. 1985. Haricot bean tannins: a review of nutritional

implications. J Am Oil Chem Soc 62:541�/549.

386 E. A. Shimelis & S. K. Rakshit

Int J

Foo

d Sc

i Nut

r D

ownl

oade

d fr

om in

form

ahea

lthca

re.c

om b

y U

nive

rsity

of

Sout

hern

Cal

ifor

nia

on 0

4/09

/14

For

pers

onal

use

onl

y.

Sathe SK, Deshpande SS, Reddy NR, Goll DE, Salunkhe DK. 1983. Effects of germination on proteins,

raffinose oligosaccharides and antinutritional factors in the great northern beans (Phaseolus vulgaris L.). J

Food Sci 48:1796�/800.

Satterlee LD, Bembers M, Kendrick JG. 1975. Functional properties of the great northern bean (Phaseouls

vulgaris ) protein isolate. J Food Sci 40:81.

Salunkhe DK, Kadam SS. 1989. CRC Hand book of World food legumes: Nutritional chemistry, processing

technology, and utilization. In: Legumes in human nutrition: future prosepects, Volume III. Boca Raton,

Florida: CRC press, Inc. pp 311�/314.

Shimelis AE, Rakshit SK. 2005. Proximate composition and physico-chemical properties of improved dry

bean (Phaseolus vulgaris L.) varieties grown in Ethiopia. J Food Sci Technol (LWT) 38:331�/338.

Sosulski FW, Elkowicz L, Reichert RD. 1982. Oligosaccharides in eleven legumes and their air-classified

protein and starch fractions. J Food Sci 47:498�/502.

Sotelo A, Hernandez M. 1980. Nutritional evaluation of three varieties of beans (Phaseolus vulgaris ) using

chemical and biological methods. Nutr Rep Int 22:607�/616.

Thorn KA, Tinsley AM, Weber CW, Berry JW. 1983. Antinutritional factors in legumes of the sonoran

desert. Ecol Food Nutr 13:251�/256.

Trugo LC, Ramos LA, Trugo NMF, Souza MP. 1990. Oligosaccharide composition and trypsin inhibitor

activity of P. vulgaris and the effect of germination on the a-galactoside composition and fermentation in

the human colon. Food Chem 36:53�/61.

Vadivel V, Janardhanan K. 2000. Nutritional and anti-nutritional composition of velvet bean: an under-

utilized food legume in South India. Int J Food Sci Nutr 51:279�/287.

Antinutritional factors and protein digestibility of haricot bean varieties 387

Int J

Foo

d Sc

i Nut

r D

ownl

oade

d fr

om in

form

ahea

lthca

re.c

om b

y U

nive

rsity

of

Sout

hern

Cal

ifor

nia

on 0

4/09

/14

For

pers

onal

use

onl

y.