Effect of the seed coat on the hardening of common beans (Phaseolus vulgaris)

Samples of cotyledons and whole black beans (Phaseolus vulgaris), Tamazulapa variety were stored during six weeks at 37 degrees C and 90% relative humidity to establish chemical and physical changes which occur during storage, and to determine the role played by the seed coat in the hard-to-cook phenomenon. After the storage period, samples of whole beans were divided in two subsamples, with and without the seed coat. These two samples and the cotyledons were analyzed for cooking time, water absorption, dietary fiber, tannic acid, soluble pectins and phytic acid. Cooking time of the whole beans increased from 99 to more than 480 minutes in the six-weeks period; for the cotyledons this value increased from 45 to 111 minutes. Cooking time of the dehulled bean, stored as whole bean, increased from 45 to 111 minutes. Cooking time of the dehulled bean, stored as whole bean, increased from 45 to 103 minutes. Water absorption in the whole beans and the cotyledons decreased, although in the cotyledons it was higher, due perhaps to the great absorption capacity to the seed coat. No changes were observed in the dietary fiber content of the cotyledons nor in the beans dehulled after storage. However, in the whole grains neutro-detergent fiber decreased, while acid detergent fiber, cellulose and lignin did not present significant changes. On the other hand, soluble pectates decreased in the whole bean and in the cotyledons; nevertheless the tannin content (as tannic acid) decreased only in the whole beans (from 3.28 to 1.64 mg/g). The data obtained suggest that the seed coat plays a significant role in the hard-to-cook process of hardening of the bean, before and during storage.     

Relation between the digestibility and protein value of the common bean (Phaseolus vulgaris)

The main nutritional limitations of common beans are the low digestibility of their protein and the deficiency of the latter in sulfur amino acids. Analysis of the information presented indicates that with 57 samples of different color (23 red, 21 black, 10 white and 3 brown), no relationship was found between protein digestibility and its quality as measured by NPR. Nevertheless, white beans have a higher protein digestibility than black, red and brown. The greater digestibility of white beans, however, does not increase the protein quality when mixed with cereal grains above that observed with black and red, probably because the protein that gives the higher digestibility is highly deficient in its sulfur amino acids content. These aspects require further research for programs aimed at increasing the nutritive value of food grain legumes.     

Effect of pectinase and cellulase addition on in vitro digestibility of common bean (Phaseolus vulgaris)

Effect of commercial pectinase and cellulase addition on in vitro digestibility of two common bean (Phaseolus vulgaris) varieties, black (Brunca) and red (Chirripó), was measured. Constant conditions of pH (6.3-6.4), time (60 min), and temperature (40 degrees C) were held, and three enzyme concentrations were tested: 0.25%, 0.5% and 1.0% m/m. In vitro digestibility increases for black beans were 6.9%; 9.5% and 12.3% (p < 0.05), and for red beans were 8.9%; 10.2% and 12.9% (p < 0.05), with increasing pectinase concentration. Effects of cellulase were dependent upon both, enzyme concentration and bean variety. In vitro digestibility of red beans increased by 5.7%; 9.2% and 12.0% with increasing cellulase concentration; digestibility of black beans increased by less than 5%. No significant difference (p > 0.05) in general acceptance of enzyme treated beans (black or red) or nontreated beans was noted.     

Bioavailability of amino acids in beans (Phaseolus vulgaris)]

Biological availability of amino acids of three common bean (Phaseolus vulgaris) varieties was evaluated in four, healthy adult subjects, consuming bean-based diets by the amino acid absorption technique and the short-term nitrogen balance method. The amino acid composition was determined according to the ionic interchange method, and tryptophan was estimated by a colorimetric procedure. The essential amino acid (EAA) and non-essential amino acid (NEAA) pattern suggests that no significant differences in content exists in the three bean varieties. When the EAA patterns were compared with those of FAO/WHO, the limiting AA in decreasing order were found to be: tryptophan, valine and threonine (sulfur AA are not considered because the hydrolysis used in this study destroys them); and the AA surpassing the reference pattern were the aromatic AA and isoleucine. Apparent (AD) and true (TD) digestibilities of the EAA fluctuated between 33 and 59% and 60 and 85%, respectively, for black beans. With red beans, these results diminished: 29 and 55% AD and 64 and 81% TD, while for white beans the limits extended: 18 and 57% AD and 36 and 86% TD. Valine proved to be the EAA of lower biological availability, and lysine and phenylalanine the most available. It is suggested that the low digestibility of valine could be due to the amino acid imbalance existing in the bean protein, since this contains an excess of isoleucine and leucine in relation to valine. The AD and TD of the AAE with respect to the NEAA were of 0.89 and 0.98 for black bean, 0.89 and 0.96 for the red and 0.77 and 0.90 for the white, which indicates that biological availability of the NEAA is higher than that of the EAA. Findings thus confirm that biological determination of the TD of protein permits prediction of the TD of the AA, since a positive correlation (r = 0.93) statistically significant was found (p less than 0.05) among them. Utilization of the TD parameter instead of that of AD to estimate the protein quality is therefore recommended.     

Inhibition of soybean oil oxidation by extracts of dry beans (Phaseolus vulgaris)

Polyphenolic compounds were extracted from pinto, kidney, white (Great Northern), pink, and black beans by hot methanol extraction and added to soybean oil. Oil oxidation was assayed by thiobarbituric acid-reactive substances (TBARS). All bean polyphenolics extracts exhibited similar antioxidant capacity in delaying the onset of iron-catalyzed oxidation better than butylated hydroxyanisole (BHA), propyl gallate (PG), and ascorbic acid. Bean polyphenolic compounds were stable after heating to 50°C and maintained their antioxidant potential after 3 mon at 4°C. Bean extracts effectively inhibited iron-catalyzed oxidation of soybean oil, probably by chelating metal ions, because no antioxidant effect was observed when soybean oil was oxidized without an iron catalyst.     

Effect of various solvents on the extraction of protein fractions of beans (Phaseolus vulgaris)

A study was carried out to determine the effect of different solvents on the extraction of protein fractions in beans. Black bean protein was extracted with the following solvents: distilled water, 0.01 M sodium hydroxide, 0.05 M sodium chloride, and 70% ethanol. By using each solvent under different conditions, it was possible to establish the optimum ones for the best extraction and fractionation of proteins from leguminous seeds. These conditions were the following: one hour agitation at room temperature, three successive extractions with the same solvent, and a ratio of solid to solvent of 1:20 W/V. The effect of 24 different sequences of solvents upon the extraction of protein was also investigated. From the extraction point of view, the best sequence of solvents for extracting the protein was that where NaOH constituted the first solvent used; this sequence, however, has the disadvantage of extracting all the protein from the seed, making it impossible to separate other protein fractions by another solvent. If the purpose of the extraction is to separate different protein fractions, the best sequence of solvents is distilled water or sodium chloride in the first place, followed by ethanol and sodium hydroxide. The need for using standardized methodology for the fractionation of protein from seeds in order to obtain comparable data between research laboratories is emphasized.     

Protein digestibility and energy in diets based on rice and beans in human adults

Four studies were carried out for the purpose of measuring the digestibility of diets based on rice and beans (Phaseolus vulgaris), and in order to quantify the effect of their supplementation with animal protein (milk) and energy (oil), on the energy and protein digestibility of such diets in human adults. Diets were offered so that they supplied 46, 72, and 103 mg N/kg/day. When the basal diet--where rice provided 60% of the protein and beans 40%--was administered at a level of 102.5 mg of nitrogen/kg/day and 49.5 Kcal/kg/day of gross energy, an apparent and true nitrogen, energy and metabolizable energy digestibility of 59.1, 70.8, 93.8 and 92.5%, respectively, were observed. When substituting 10% of the vegetable protein by milk protein in the same diet, the same indicators revealed a digestibility of 65.3, 76.8, 93.5 and 92.1%, respectively. The information indicates that supplementation with animal protein improves nitrogen absorption at any of the energy levels studied. In contrast, caloric supplementation does not have any positive effect on nitrogen or energy absorption. It was also found that nitrogen apparent digestibility increases significantly when the N level in the diet is raised, and stabilizes when intake exceeds 100 mg nitrogen/kg/day. It is therefore proposed that for digestibility studies in diets where animal protein is utilized at a nitrogen level of around 120 mg/kg/day, true digestibility remains constant, no matter what nitrogen level is used in the diet.     

Effects of traditional cooking on antinutritional factors of the black beans (Phaseolus vulgaris) of Costa Rica]

Trypsin inhibitors, alfa amylase inhibitors and hemagglutinins were determined in black beans (P. vulgaris) produced in Costa Rica. The effect of the traditional cooking on such antinutritional factors was also studied. The antinutritional factors were analyzed spectrophotometrically in the raw beans, as well as after several cooking periods of time. The results showed that alfa-amylase inhibitors were the most thermoresistant. After 30 min of cooking time there was a 33% of activity left from the initial activity of the raw beans. Approximately 80% of the antitryptic activity was destroyed at 9 min of cooking time. After 10 min of cooking time, only 1% of hemagglutinin activity was present.     

Biochemical and nutritional value of seeds of the lima bean (Phaseolus lunatus) in comparison with those of the common bean (Phaseolus vulgaris)

Composition in nutrients and antinutritional factors, digestibility and growth in rats fed diets prepared with raw and cooked beans of Ph. vulgaris, cultivar "Tacarigua", and Ph. lunatus cultivar "Tapiramo", are compared. Grains from both cultivars are similar in appearance, taste, nutritional value, and acceptability. Protein and phosphorus contents were greater in Ph. vulgaris than in Ph. lunatus seeds. The chemical score and availability of lysine were better in Ph. lunatus. Diets prepared with raw beans from Ph. lunatus resulted non toxic for the rats during a 12-day period of feeding. All rats fed with raw beans from Ph. Vulgaris died in the same period of time. Protein efficiency was better with cooked beans of Ph. lunatus. The cultivar "Tapiramo" (Ph. lunatus) is recommended for autoconsumption by small farmers.     

Trypsin inhibitory activity of beans (Phaseolus vulgaris L.): critical evaluation of methods for determination

High values of residual trypsin inhibitory activity found for heat-treated beans indicated the occurrence of artifices due to the methodology. A critical evaluation of the methods in use and of possible interferents was performed trying to determine the most adequate way of measuring residual trypsin inhibitory activity. Results showed that extraction conditions, pH of reaction and sample preparation are responsible for significant alterations of the values found, requiring careful standardization. This is the first report about the influence of lyophilization upon residual trypsin inhibitory activity of cooked beans.     

Lipid classes,fatty acid composition and triacylglycerol molecular species of kidney beans (Phaseolus vulgaris L.)

Seed oils from five legume cultivars of Phaseolus vulgaris, grown in Japan, were extracted and classified by thin‐layer chromatography (TLC) into seven fractions: hydrocarbons (HC; 0.7–1.4 wt‐%), steryl esters (SE; 1.7–3.3 wt‐%), triacylglycerols (TAG; 33.8–45.9 wt‐%), free fatty acids (FFA; 0.6–1.5 wt‐%), sn‐1,3‐diacylglycerols (1,3‐DAG; 0.3–1.0 wt‐%), sn‐1,2‐diacylglycerols (1,2‐DAG; 0.4–1.2 wt‐%) and phospholipids (PL; 49.4–58.8 wt‐%). Fatty acids derivatized as methyl esters were analyzed by gas chromatography (GC) and a flame ionization detector. Molecular species and the fatty acid distribution of TAG isolated from the total lipids in the beans were analyzed by a combination of argentation‐TLC and GC. A modified argentation‐TLC procedure, developed to optimize the separation of the complex mixture of total TAG, provided 18 different groups of TAG, based on both the degree of unsaturation and the total length of the three acyl chains of fatty acid groups. SDT (3.2–4.2 wt‐%), M₂T (3.8–5.0 wt‐%), D₃ (4.8–5.9 wt‐%), MDT (8.0–13.9 wt‐%), D₂T (12.5–15.8 wt‐%), MT₂ (19.4–22.7 wt‐%), DT₂ (17.8–23.5 wt‐%) and T₃ (9.2–13.0 wt‐%) were the main TAG components. The dominant fatty acids of TAG were α‐linolenic (48.5–57.8 wt‐%) and linoleic (16.7–25.8 wt‐%) acids, with appreciable amounts of palmitic (8.3–13.2 wt‐%) and oleic (7.8–13.8 wt‐%) acids. The high content of α‐linolenic acid in the cultivars of P. vulgaris could very likely play a beneficial role in reducing the risk of coronary heart disease among the large populations consuming them in Japan.     

Evaluation of nutritional potential of fish in diets based on beans (Phaseolus vulgaris) and a cereal/corn (Zea mays) and/or rice (Oryza sativa)

p6e complementation between corn and fish, and rice and fish was evaluated for the purpose of establishing the required levels of each constituent in the mixture to obtain the optimum value in the biological evaluations for each diet. The optimum fish levels were around 10 and 6% for the corn and rice diets, respectively. Complementary levels of fish in the bean: corn and bean:rice diets were evaluated in the same manner. The best values in the biological evaluation were obtained with only 2% of fish. The economical analysis of these mixtures revealed that the nutritional value of the Central American rural diets can be increased with the introduction of fish in small quantities in the habitual diets, without increasing the family food expenses.     

Effect of home-processing in the preparation of pinto beans (Phaseolus vulgaris L.) on the tannin content and nutritive value of proteins

A 3(2) factor design was carried out in order to investigate the different home-cooking treatments applied in the preparation of pinto beans (Phaseolus vulgaris L.) on the nutritive value of their protein. The factors studied were previous soaking, type of cooking and addition of cooking broth. Biological evaluation of the protein was performed, and the protein efficiency ratio (PER) and apparent digestibility of the protein (DAP) values were obtained. The tannin content was measured in hulls, cotyledons and in the cooking broths of each experimental treatment. The most significant effect of the PER value was the type of cooking (P less than 0.0001), followed by the addition of cooking broth (P less than 0.05) as well as a significant interaction between cooking method and addition of broth (P less than 0.025). Soaking did not have significant effects per se or through its interactions in relation to PER. The highest values for PER and DAP were obtained with the boiling treatment without broth. The detrimental effect of the cooking broth can be explained by its tannin content (108.5-272.25 mg Eq. catechin/100g).     

Flour of hard bean (Phaseolus vulgaris) in the preparation of bread]

In order to utilize hardened beans, we proposed to find the method most indicated for the preparation of bean flour to determine their nutritional value, and to make bread of high industrial, nutritional quality, and good sensory characteristics, using blends of bean and wheat flours. Two types of flour were prepared, testing four soaking temperatures (22, 30, 40 and 50 degrees C) and two methods to remove the testa (under moist and dry conditions). At laboratory level, the dry testa removal method gave the best flour yields (mean = 85.8%) and the highest protein content (mean = 23.7%). Comparison between soaking temperature at 30 and 50 degrees C was not significant (alpha = 0.05). At pilot plant level, with soaking at 50 degrees C the flour yields were 58.0% for moist testa removal (H1) and 74.0% for dry removal (H2), with a protein content of 22.6% for H1 and 23.0% for H2. The H1 and H2 flours were added to wheat flour at 5, 10 and 15% for bread making. The addition of 5.0% gave breads with similar protein content and sensory characteristics to those of the control, wheat. A diet based on bean-flour bread resulted in greater weight gains than that with casein for gold hamsters. The study also demonstrated the importance of heat-treating of the bean flours, because when flour without previous heat treatment was administered, the animals lost weight and died. This effect was overcome by the process of baking the flours at 140 degrees C for four hours.     

Antioxidant activity of pea bean (Phaseolus vulgaris L.) extract

Antioxidative activity of pea bean (Phaseolus vulgaris L.) extract was evaluated by using a linoleic acid system, and the methanol extract exhibited strong antioxidative activity as measured by the thiocyanate method. The crude methanol extract was partitioned between then-butanol phase (BP) and the water phase (WP). Then, the antioxidative activity of the BP and the WP was determined by using a linoleic acid system. The WP showed strong antioxidative activity, while BP showed only weak activity as measured by the thiocyanate method. Next, the synergistic antioxidative action of WP with α-tocopherol was examined by using linoleic acid and liposome systems. The WP had a synergistic effect with α-tocopherol in both the food model and liposome systems. For purification and isolation of the antioxidative substances of the pea bean, preparative high-performance liquid chromatography was carried out with an octadecylsilyl column. Five fractions were collected, and antioxidative activity was determined in a linoleic acid system. Although fraction 1 had strong activity by the thiocyanate method, the purification of this active fraction was difficult; therefore, the partly characterized active fraction was investigated. The contents of total phenolics and sugars were 0.31±0.01 mg/g of fraction 1 and 406.1±0.1 mg/g, respectively. The ninhydrin chromogenic reaction was positive, and the ultraviolet absorption spectral λ max value in distilled water was 264.0 nm, indicating that the water-soluble antioxidative components from pea bean may be a new type of antioxidant. Isolation and identification are currently being investigated.     

Development of an intermediate moisture food from bean (Phaseolus vulgaris L.)

Beans consumption has been associated to reduction on chronic, non transmissible, diseases development. Generally, its consumption is less to the recommended and it is done principally as whole grain dishes. To increase the consumption, there is an especial interest in the use of new products. The main goal of this research was to design intermediate moisture bean purees (IMP) using soaked, cooked and grained Tortola bean, removing an important testa portion. In preparation of IMP two moisture levels, 25 and 30%, and two glycerol levels, 10 and 15%, were studied. Purees were preserved at ambient temperature (20 +/- 2 degrees C) for 30 days. Proximal analysis, phytate content and trypsin inhibitors were determined in the original non processed purees. IMPs were analyzed at preparation time and after 15 and 30 days of storage for moisture content, pH and water activity. Besides, microbiological analysis for total plate count on aerobic mesophile microorganisms, molds and yeast, total colifoms, fecal coliforms and Staphylococcus aureus, was carried out. Global quality and sensory acceptance was also determined. IMPs presented a(w) values between 0.800 and 0.844, a pH between 6.20 and 6.24 and the microbiological counting was negative or far below the accepted limits for more strict foods. IMPs presented good qualifications for global quality and were well accepted. Sensory parameters maintain their values during storage, except for color that in treatment with 30% moisture and 10% glycerol showed a light darkening. It is possible to elaborate intermediate moisture bean puree, with low level of antinutritional compounds, good quality and sensory acceptance and with adverse conditions for the development of food safety importance microorganisms.