Nutritional evaluation of kidney beans (phaseolus vulgaris): The toxic principle

Kidney bean (Phaseolus vulgaris) lectins were purified by affinity chromatography on a fetuin-Sepharose-4B column. The net protein utilisation (NPU) of rats fed on a 5% casein-containing diet was strongly depressed by these pure lectin preparations. The extent of this nutritional toxicity was found to be related to the lectin content of the diet according to the following equation: NPU = NPU_{5% casein} ?280 x (where x is the lectin content in % w/w). Thus, because in addition lectin-free kidney bean protein preparations were found to be non-toxic for rats, it is now suggested that the toxic principle of kidney bean is identical with its constituent lectins.     

Nutritional evaluation of kidney beans (Phaseolus vulgaris): chemical composition, lectin content and nutritional value of selected cultivars

The chemical composition, lectin content and nutritional value of selected cultivars of kidney beans (Phaseolus vulgaris) were determined. Mainly due to different amounts of reserve globulins deposited, seed N content varied between 3.4 and 5.0%. The amino acid composition and the corresponding chemical score values of 40-60 however, were similar for all the beans, with the sulphur-containing amino acids limiting. Despite similarities in composition, 11 out of the 13 cultivars examined were highly toxic for rats in the raw state. These were all found to contain high concentrations of haemagglutinating lectins (over 10% of the total protein). On the other hand, two low-lectin bean varieties, Pinto III and Great Northern, had no appreciable disruptive effects on the intestines and were essentially non-toxic for rats.     

Nutritional value of cooked beans (Phaseolus vulgaris) and their isolated major protein fractions

The digestibility and nutritional properties of whole cooked beans (Phaseolus vulgaris L) and their isolated and cooked major protein fractions were evaluated in rats. Isolated globulin GI was highly digestible (89.5%) but had a low NPR value (1.51). The albumins and glutelins exhibited intermediate digestibilities (79.1 and 73.2%) and a biological utilisation NPR of 3.18 and 2.91, respectively, 30% lower than casein. Whole beans exhibited the poorest digestibility (62.8%) with a faecal excretion of more than 30% of the ingested nitrogen and an intermediate NPR of 2.27. There was a direct relation between the amount of ingested dietary fibre and dry matter and N excretion. Enrichment of whole beans with the isolated albumin fraction, rich as it is in sulphur amino acids, did not improve NPR value. Dry beans apparently contain components producing undigestible protein complexes which affect amino acid availability and increase endogenous nitrogen excretion.     

Nutritional evaluation of soya beans (glycine max): Nitrogen balance and fractionation studies

The poor nutritional performance of rats fed raw soya-bean-containing diets appeared to be due to reduced apparent digestion and absorption of dietary protein, coupled to changes in systemic metabolism leading to a poor overall nitrogen balance. Aqueous heat treatment greatly reduced but did not eliminate the antinutritional effect. Heat treatment with aqueous ethanol was more effective. The whey protein (pH 4.8 soluble extract) fraction contained the bulk of the trypsin inhibitor and haemagglutination activity and gave the poorest net protein utilisation value. However, an eight-fold increase in trypsin inhibitor content did not significantly effect apparent nitrogen digestibility. Therefore inhibition of gut proteolytic enzyme activity in vivo by soya bean trypsin inhibitors did not account fully for the poor nutritional performance. The problems elicited by soya bean are not transitory and thus there was a cumulative deterioration in overall performance for 16 weeks as a result of continuous exposure to soya bean.     

Protein hydrolysates obtained from Azufrado (sulphur yellow) beans (Phaseolus vulgaris): Nutritional,ACE-inhibitory and antioxidative characterization

The goals of the present work were to evaluate the nutraceutical and functional properties of protein hydrolysates obtained from three cultivars of Azufrado (sulphur yellow) beans. Bean protein concentrates were obtained and digested with Alcalase?, Thermolysin? and Pancreatin?. The Azufrado Higuera cultivar showed the best protein yield/concentration ratio, having a higher amount of hydrolysates compared to the rest of the varieties. All treatments presented ACE-Inhibitory activity, these values ranged from 0.109 to 319.96 μg/ml. Regarding to antioxidant activity, the Az. Higuera/alcalase treatment showed the highest DPPH scavenging activity (40%), however with the ABTS method the Az. Regional ’87-alcalase was the best treatment (99.89% of scavenging). Overall, the results of our work showed that Azufrado beans proteins hydrolysates are suitable for development of a nutraceutical product for prevention and control of degenerative diseases such as hypertension and those derived from cellular oxidation.     

Proteolytic breakdown of kidney bean (Phaseolus vulgaris) storage proteins: Nutritional implications

Glycoprotein II, the major storage protein of the seeds of kidney bean (Phaseolus vulgaris), was largely resistant to hydrolysis by pure gut endopeptidases. However, the protein was extensively digested in vitro and nearly 90% of it became soluble in 5% trichloroacetic acid by treatments first with extracts of rat stomach followed by intestinal contents or alternatively first with pepsin, followed by pancreatin. Heat denaturation (100°C for 10 min) had no appreciable effect on the digestion. A similarly high extent (between 80 and 90%) and rate of digestion of pure Glycoprotein II was observed in vivo. However, intubation of pure Glycoprotein II into the stomach of previously fasted rats increased the production of insoluble intestinal secretions containing relatively large amounts of nitrogen. As this N passed into the caecum, it reduced both the apparent digestibility of Glycoprotein II and the net gain of N for the animal. Moreover, in the presence of a mixture of raw bean proteins in the stomach of rats the time taken to empty its content into the intestine was increased appreciably. Additionally, the toxic effects of the lectins in these mixtures, particularly on continuous feeding, were observed.     

Nutritional response of mature rats to kidney bean (Phaseolus vulgaris) lectins

In a series of 10-day pair feeding experiments it was found that the nutritional value of diets containing beans was essentially the same for rats aged between 30 and 123 days. Thus net protein utilisation (NPU) values of 25–39 on diets containing Processor bean (35 g protein kg^?1) + egg albumin (65g protein kg^?1) were obtained. As food intakes were considerably reduced when rats were fed diets containing more than 35g protein kg^?1 of Processor bean, the measurement of protein utilisation became increasingly more difficult. The severe disruption of the brush borders of duodenal and jejunal enterocytes, originally observed when bean-containing diets were fed to young (30-day-old) rats was also found with rats up to the age of 120 days on similar diets. Similarly, the development of circulating anti-lectin antibodies in the animals showed no age dependence within the age limits investigated. It was also shown that oral immunisation did not protect the rats from the effects of toxicity and that the immune response was a result of continuous absorption of lectin throughout the feeding period. Thus the extent and the mechanism of toxicity of Phaseolus vulgaris bean lectins were found not to be dependent on the age or maturity of the animal.     

The nutrition evaluation of kidney beans (Phaseolus vulgaris). The effect of nutritional value of seed germination and changes in trypsin inhibitor content

The total N content of kidney beans (Phaseolus vulgaris) was found to increase on germination. The overall amino acid composition however changed very little. Rats fed on a diet containing raw beans lost more weight than the protein-free controls (negative n.p.u. value). Germination was found to bring about a gradual improvement in nutritive value probably through the elimination of some of the toxic constituents of the seed. The near doubling of the amount of trypsin inhibitors by the 8th day of germination taken together with the substantial improvement in the nutritive value of the bean appeared to rule out trypsin inhibitors as the main toxic components of raw beans.     

Toxicity of kidney beans (Phaseolus vulgaris L). to conventional and gnotobiotic rats

Raw and irradiated diets containing kidney beans as the sole source of protein and providing 10% crude protein (N × 6.25) produced severe weight loss, followed in some cases by death, in conventional hooded rats. The mean weight loss of the surviving rats exceeded the mean weight loss of control animals fed a non-protein diet. When fed to gnotobiotic rats the irradiated bean diet produced a slight gain in the mean weight of the animals over the 10 day experimental period and a net protein utilisation (n.p.u.) of 16. This figure fell far short of the value of 52 estimated from the chemical score. Diets containing beans + casein, each providing 5% crude protein gave n.p.u. value of 53 in gnotobiotic rats, a figure which approached that anticipated from the chemical score of the diet (=61). In conventional rats the same diet gave n.p.u. values of 14 (non-irradiated) and 16 (irradiated).     

Effects of sprouting on nutrient and antinutrient composition of kidney beans (Phaseolus vulgaris var. Rose coco)

 Kidney beans (Phaseolus vulgaris) were being processed for inclusion into a weaning food formulation. They were sprouted for 96 h at 30  °C and some nutrients and antinutrients were evaluated every 12 h. During the entire sprouting period, starch content decreased by 55.6%. This was accompanied by an increase in reducing and non-reducing sugars from 0.19 to 9.46 and 1.87 to 4.16 g/100 g dry matter (DM) respectively. These carbohydrate changes were due to an increase in amylolytic activity, as evidenced by a more than fivefold increase in diastatic activity. Tannins decreased to undetectable levels, and trypsin inhibitor substances and phytates decreased by 70.7% and 85.9% during the entire sprouting period. In vitro protein digestibility, which is negatively affected by these antinutrients, increased by 17.1% during the same period. HCl extractability of Ca, Fe and Zn increased by 55.2%, 54.7% and 53.0%, respectively. Received: 6 March / Revised version: 10 April 2000     

Nutritional assessment of protein from beans (Phaseolus vulgaris L) processed at different pH values,in growing rats

The effect of the commonly used processing techniques of soaking (at different pH values) and cooking on the digestive and metabolic utilisation of protein from common beans (Phaseolus vulgaris L) in growing rats was studied. Before the cooking step, beans were soaked in solutions of pH 2.6, 5.3 or 8.4. Analyses of beans soaked at moderately acid pH (5.3) showed a significant increase in essential amino acids, especially cysteine. Food intake and growth indices were also dependent on pH. All indices were better in animals fed with beans soaked in a basic pH solution than when an acid soaking solution was used. In contrast with the findings expected on the basis of the chemical analysis of protein composition of the food, the worst results for food intake and growth were found in rats fed with beans soaked at pH 5.3. There were no significant differences in apparent digestibility coefficient between different groups of animals. The highest metabolic utilisation of protein (balance) was found in animals fed with beans soaked in a basic solution; however, the values were insufficient to account for the faster rate of growth in this group. The better growth rate was probably due to the improved utilisation of carbohydrates in beans soaked in the basic pH (8.4) solution. © 2001 Society of Chemical Industry     

Lactic acid fermentation of black beans (Phaseolus vulgaris): microbiological and chemical characterization

Legumes, and particularly Phaseolus vulgaris, are an important source of nutrients, especially in developing countries. In spite of being part of the staple diets of these populations, their consumption is limited by the flatulence they produce. Natural lactic acid fermentation has proved to be an effective method to decrease flatulence‐producing compounds. However, in order to use this method as a process on a large scale, it is fundamental to identify the microbial flora involved. When fermented seeds of Phaseolus vulgaris (black bean) were analysed microbiologically, it was found that the microorganisms present were Lactobacillus casei and Lactobacillus plantarum. On performing back‐slopping or induced fermentation with different inocula, a 63.35% decrease was found for the soluble fibre and 88.6% for raffinose, one of the main flatulence‐producing compounds. When cooking under atmospheric pressure was applied to the fermented samples, a significant diminution of the trypsin inhibitors and tannins was found as well as an increase in the in vitro and in vivo digestibility of the beans. All these results demonstrate that the lactic acid bacteria used for the induced fermentation can lead to a functional food with improved nutritional quality. Copyright © 2006 Society of Chemical Industry     

Phenolics and antioxidative activities in common beans (Phaseolus vulgaris L)

Six bean cultivars grown in southern Manitoba for 2 years were evaluated for variability in yield of millstreams and phenolic constituents. The ethanolic extract of bean cultivars and millstreams was screened for antioxidant activity using the β‐carotene‐linoleate and the 1, 1‐diphenyl‐2‐picrylhydrazyl (DPPH) in vitro model systems. Cultivar was the main source of variation for yield of millstreams, content of phenolic compounds and antioxidant activities. Phenolic compounds in cultivars varied from 3.3 to 16.6 mg catechin equivalent and from 0.15 to 0.32 mg cyanidin‐3‐glucoside equivalent g^?1 bean for total phenolic and anthocyanin contents, respectively. The bean cultivars exhibited antioxidant activity (AA) of 10–46% inhibition of lipid peroxidation in the linoleate and 0.4–1.3 trolox equivalent antioxidant capacities (TEAC) in the DPPH model systems. The hull millstream with maximum concentration of phenolic compounds exhibited the strongest antioxidant activity of 383 µM trolox equivalent g^?1 hull. Total phenolic content, alone or in combination with other phenolic constituents, is a potential candidate as a selection criterion for antioxidant activity in beans. Copyright © 2005 Society of Chemical Industry     

Interpretation of the force deformation curves of soaked red kidney beans (Phaseolus vulgaris L.)

In this study, the textural patterns of red kidney beans soaked in water at 20, 30, 40 and 60 °C are reported. Texture (hardness) was measured instrumentally by cutting with a wedge-type blade mounted on an Instron Universal Testing Machine at a speed of 200 mm min⁻¹. The general trend of the force deformation curves was similar for all of the soaking temperatures studied throughout the soaking process. At initial stages of hydration, textural changes were a function of the soaking time. However, once the hydration process attained equilibrium, changes in texture became minimal and were within the range of 34 ± 2 N, regardless of the soaking temperature and hydration time. The force deformation curves were influenced by the presence of a large cavity between the two cotyledons of red kidney beans. Interpreting textural patterns of soaked beans would provide a better control of the water absorption process, which subsequently influences changes in texture.     

Effect of processing on available carbohydrate content and starch digestibility of kidney beans (Phaseolus vulgaris L.)

The effects of different soaking and cooking methods were investigated on available carbohydrate content and starch digestibility of red and white kidney beans. Total soluble sugars, reducing sugars, non-reducing sugars and starch contents of red and white kidney beans were 9.95 and 11.3%, 0.82 and 0.96%, 9.13 and 10.3%, and 44.4 and 47.8%, respectively. All these available carbohydrate components decreased to various extents as a result of soaking and cooking. From 2.51 to 13.6% and 7.03 to 28.0% of total soluble sugars were lost on soaking kidney beans in tap water and sodium bicarbonate solution, respectively. However, losses in total soluble sugars were maximum (19.9–60.9%) on cooking pre-soaked kidney beans. Losses in starch contents were 4.27 to 24.7% and 30.4 to 70.7% as a result of the soaking and cooking processes, respectively. Besides these losses, starch digestibility of kidney beans was also markedly improved as a result of cooking. However, no appreciable improvement in starch digestibility was observed after soaking kidney beans in water or alkaline solution.     

The biology and control of Zabrotes subfasciatus (Boheman) (Coleoptera: Bruchidae) infesting red kidney beans

Experiments were set up to determine the pattern of development of a South American strain of Zabrotes subfasciatus infesting red kidney beans. The duration of the life cycle was 36 days from egg to adult and after a pre-oviposition period of less than one day females laid 50 eggs in their 13 day life. Most of the eggs were laid after 4 days and 90% hatched. ‘Windows’ developed in the beans after 26 days. Dilute dust insecticides were admixed with beans containing young larvae and with beans with ‘windows’. The treatments did not prevent emergence of the adults but killed them thereafter. Survivors were found on tetrachlorvinphos and bromophos treated beans but not on any others. Adults put on to treated beans at various intervals after treatment were initially killed by all insecticides. Malathion, however, lost its activity within 6 weeks and gamma-HCH was the most persistent being effective up to 24 weeks. For the period for which farmers would require to protect their beans in storage, about 8 weeks, iodofenphos or pirimiphos-methyl applied at 8 ppm would be good alternatives to gamma-HCH.     

Thermal inactivation kinetics of peroxidase and lipoxygenase from fresh pinto beans (Phaseolus vulgaris)

 Thermal inactivation kinetics of crude peroxidase (POX) and lipoxygenase (LOX) in fresh pinto beans were studied over the temperature range of 55–90°C. The inactivation of both enzymes followed first-order kinetics. The biphasic inactivation curves for POX indicate the existence of several isoenzymes of varying heat stability. In the temperature range of 55–70°C, the activation energies (E _a) of POX were 46.5 kcal·mol^–1 for the heat-labile portion and 37.6 kcal·mol^–1 for the heat-stable portion. On the other hand, the LOX enzyme had an E _a value of 42.26 kcal·mol^–1 at 55–75°C and 49.1 kcal·mol^–1 at 55–90°C. Received: 28 July 1997 / Revised version: 16 October 1997