Bean Hardness Research Articles

Hydrothermal treatments affect the development of the hard‐to‐cook defect in cowpeas

AbstractThe hard‐to‐cook defect is a well‐known problem in stored legumes, including cowpeas, which reduces the consumption and utilization of these nutritious foods. It is a generally held view that the enzyme, phytase is involved in the development of the defect. The effectiveness of steam treatments in preventing the characteristic hardening of cowpeas stored under unfavorable conditions was investigated. The factors considered were steaming temperature (100°C, 121°C), steaming time (2, 4, and 6 min) and initial seed moisture content (13%, 20%). The treated cowpeas were stored at either 4°C (no relative humidity [RH] control) or 42°C/80%RH. The texture of cooked treated cowpeas was comparable with the control; the peak forces were 504–639 N and 616 N, respectively, for treated and control cowpeas before storage. Although the treatments reduced the texture of cooked cowpeas prior to storage, only steaming at 121°C for 4 or 6 min prevented hardening during storage. Steaming reduced the phytase activity of cowpeas to 53%–64% of original activity; however, a significant increase occurred with storage. Steaming and storage significantly decreased water absorption from 91.28 g/100 g to 75.68–88.02 g/100 g after 24 h soaking. A decrease in phytate content and increases in electrolyte leakage and pectin loss were also recorded. A lack of significant correlation between cooked bean hardness and the physicochemical indices implies that the improved texture of cooked treated cowpeas occurred through a pathway not typically associated with the development of the hard‐to‐cook defect in cowpeas.

Bean color and hardness modeling as a function of storage conditions

Stored carioca beans usually tend to darken and harden and therefore lose quality and commercial value and are rejected by the consumer. The objective of this study was to evaluate the behavior of four contrasting light tegument genotypes for the aging process (darkening and hardening) for six months. We adopted a mathematical data modeling, based on polynomial regression analyzes of the variables, color and texture, in the different storage conditions, to describe the effects of the treatment and the storage time, in all bean samples and to select the model which best describes the interaction between variables. All genotypes tended to harden, with increasing storage temperature and time, regardless of the degree of browning. The lowest values of hardness, after six months, were verified in both slow and fast darkening beans. The genotype most resistant to darkening was which showed significant hardening over time. In conclusion, the color itself is not the best parameter to be considered to determine the degree of aging of stored beans, which is controlled by complex mechanisms, physicochemical, genetic, biochemical, among others, which in turn are influenced by environmental storage conditions and genotype.

Aging indicators for stored carioca beans

High temperature, moisture content and radiation conditions, common in the tropics, accelerate the physiological post-harvest disorders in beans, affect integument color and bean hardness. This study explored the darkening and hardening mechanisms in carioca type beans during storage. The contrasting genotypes for bean darkening and hardening (BRS Estilo and BRS Pontal: rapid darkening and hardening; BRSMG Madrepérola and CNFC 10467: slow darkening and partially resistant to hardening; and a Canadian genotype of the Pinto Bean type resistant to darkening (negative control)) were evaluated right after harvest and after six months storage at 20.3 ± 0.2 °C and 78.9 ± 6.0% RH, with respect to their physicochemical, biochemical and morphological attributes. All the samples hardened with time, but the velocity of darkening did not always parallel the degree of hardening of the beans (that increase linearly with time), which indicates that the color of the bean integument was not a safe indicator to predict the culinary quality of carioca beans. During storage, the SOD (superoxide dismutase) activity and LP (lipid peroxidation) in the cotyledon increased, and the increase was more significant in the integument of the rapid-darkening genotypes. The oxidative stress detected in the beans apparently started in the green bean formation phase, continuing during post-harvest, especially for the rapid-darkening beans. Quantification of the bivalent ions in the bean fractions, together with the degree of membrane damage was positively associated with bean darkening, independent of the group. Thus, aging of the carioca beans could be triggered by a complex mechanism involving diverse intrinsic factors in different degrees according to the genotype and the post-harvest period, but some parameters could serve as indicators, as cooking time, hardness and color, to differentiate between rapid and slow darkening beans.

DNA marker-assisted evaluation of cooked bean hardness of three soybean progeny lines.

Cooked bean hardness is an important trait for the processing of soybean products such as nimame, natto, miso, and soy sauce. Previously, we showed that cooked bean hardness is primarily affected by the pectin methylesterase gene Glyma03g03360, and that calcium content has a secondary effect on this trait. To establish a simple and timely method for the evaluation of cooked bean hardness, primers of amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) were designed to detect a single-nucleotide polymorphism of Glyma03g03360 and subsequently used to evaluate three soybean progeny lines. The determined genotypes were compared to those identified using the cleaved amplified polymorphic sequence (CAPS) method. Seven out of 284 lines presented different genotypes, which were determined using the two methods: A genotypes were incorrectly assigned as heterozygous by CAPS, suggesting that ARMS-PCR is more reliable. Glyma03g03360 genotypes could be used to evaluate cooked bean hardness, except for intermediate values. Cooked bean hardness within the same genotype groups was significantly correlated with calcium contents. These findings indicate that ARMS-PCR is useful for a marker-assisted selection of soybean with soft-cooked beans and that calcium content may be used for additional selection.

Effect of process-induced common bean hardness on structural properties of in vivo generated boluses and consequences for in vitro starch digestion kinetics

In the present study, we evaluated the effect of process-induced common bean hardness on structural properties of in vivo generated boluses and the consequences for in vitro starch digestion. Initially, the impact of human mastication on the particle size distribution (PSD) of oral boluses from common beans with different process-induced hardness levels was investigated through a mastication study. Then the effect of structural properties of selected boluses on in vitro starch digestion kinetics was assessed. For a particular process-induced hardness level, oral boluses had similar PSD despite differences in masticatory parameters between participants of the mastication study. At different hardness levels, a clear effect of processing (P<0·0001) was observed. However, the effect of mastication behaviour (P=0·1141) was not significant. Two distinctive fractions were present in all boluses. The first one was a cotyledon-rich fraction consisting of majorly small particles (40-125 µm), which could be described as individual cells based on microscopic observations. This fraction increased with a decrease in process-induced hardness. The second fraction (>2000 µm) mostly contained seed coat material and did not change based on hardness levels. The in vitro starch digestion kinetics of common bean boluses was only affected by process-induced hardness. After kinetic modelling, significant differences were observed between the reaction rate constant of boluses generated from the hardest beans and those obtained from softer ones. Overall this work demonstrated that the in vitro nutritional functionality of common beans is affected to a greater extent by structural properties induced by processing than by mechanical degradation in the mouth.

Assessment of Mung Bean Quality Through Single Kernel Characterization

With significant interest in incorporating beans, lentils, and pulses as nutrient-rich healthy food sources into our diets, a reliable technique for their rapid and accurate quality evaluation is needed. The method of single kernel characterization to determine the physical properties (i.e., diameter, weight, moisture content, and hardness) of mung beans was assessed in this study. Two mung bean varieties were characterized using the single kernel characterization technique and the results were compared to traditional methods. It was observed that predicted bean weights were accurate to known laboratory measurements (R = 0.98, n = 200). Individual bean characterization was moderately (R = 0.58–0.7, n = 100) correlated in regard to the true diameter of mung beans. An evaluation on moisture content was performed after tempering the two bean varieties to four moisture levels and a good correlation was obtained with the oven drying method (R = 0.92, n = 24). Hardness values obtained by single kernel characterization were moderately correlated to maximum forces measured using an Instron universal testing system. However, a common relationship was observed between mung bean hardness and moisture content when using both methods. Compared to visual inspection, automated characterization of single beans is a superior technique to measure the geometrical and mechanical properties of mung beans in an industrial setup where high throughput is paramount.

Effects of Different Storage on Qualities of Adzuki and Red Kidney Beans

&lt;p&gt;This is the first study to report the effects of frozen soil storage on adzuki and red kidney beans. Adzuki and red kidney beans were stored for 15 months in polyethylene or paper bags under three different conditions: natural cold energy storage in frozen soil, storage in a freezer at -20 °C, and storage at a constant temperature of 25 °C. Samples were collected from every treatment group every 3 months, and qualities related to processing (bean paste yield and cooked bean hardness), seed moisture content, one-hundred seed weight, seed density, and sample physical properties (electrical conductivity and soluble solid content) were evaluated. Frozen soil storage resulted in the least deterioration of important qualities in adzuki and red kidney beans. We also showed that the electrical conductivity value and soluble solid content of the liquid used for soaking beans can be used to evaluate the processing suitability of cooked beans.&lt;strong&gt; &lt;/strong&gt;&lt;/p&gt;

Hardness of carioca beans (Phaseolus vulgaris L.) as affected by cooking methods

Instrumental texture analysis is a fast and practical tool that has been used to assess bean cooking quality. However, lack of standardization for sample preparation has resulted in quite divergent reports in literature. So, five bean cooking methods were evaluated to identify and establish the best one that differentiates hardness of fresh and aged grains. Bean hardness was highly affected by cooking time and temperature. Mattson Bean Cooker and hot air oven were not adequate, providing undercooked grains with hardness above 4 N. Hardness of grains cooked on a hotplate decreased as the cooking time increased from 30 to 60 min. Likewise, with the autoclave at milder condition (105 °C/10 min) the grains were harder (2.99 N for fresh grains and 3.40 N for aged grains), while at severe condition (115 °C/20 min) softer grains were obtained (0.77 N for fresh grains and 1.01 N for aged grains). The suitable methods to prepare cooked bean for instrumental texture analyses seem to be the hotplate cooking for 45 or 60 min and the autoclave procedure at 110 °C/15 min, once they promoted the grain softening and discriminated fresh and aged beans.

Drying kinetics of the individual layer of cocoa beans during heat pump drying

Investigation was carried out to study the drying kinetics of the individual layer of cocoa beans, namely the testa and cotyledon, during heat pump drying. The cocoa beans were dried in thin layer using dehumidified air at 28.2°C, 40.4°C and 56°C. Moisture contents of the bean, testa and cotyledon were recorded during drying. Reduction in moisture content was relatively fast at the testa as compared to the cotyledon in the initial two hours of drying. Subsequent drying showed a crossover region where the moisture content of the testa was higher than the cotyledon. The final moisture content of the testa was found to be higher than the inner cotyledon at the end of drying. This showed that moisture migrated from the cotyledon (lower moisture content) to the testa (higher moisture content) during drying. Although such transfer mechanism seems contradict but this can be further explained by the mass transfer potential concept as postulated by Luikov where the transfer of moisture is due to moisture potential difference instead of moisture content difference. Product quality analyses showed percent retention of cocoa polyphenols ranged from 44% to 73% as compared to freeze dried sample. Bean hardness was found reasonably comparable to the commercial sample and increased with decreasing moisture content.

Role of Water State and Mobility on the Antiplasticization of Green and Roasted Coffee Beans

The effect of water on "antiplasticization" and plasticization of green and roasted coffee was studied by textural analysis, sorption isotherms, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR). From BET monolayer value to a(w) = 0.61 and 0.75 for green and roasted coffee, respectively, the solid matrix hydration occurred and water induced hardening. Very short NMR T(2) values and the concomitant absence of any DSC endothermic peak assignable to water freezing were observed at these a(w) values. When solid matrix hydration was completed, water started to act as a plasticizing agent, the compressive modulus started to decrease, and NMR revealed the appearance of a new proton pool with increased mobility. According to DSC, only when the plasticizing effect became important did water present enough mobility to freeze. Above this moisture value (a(w) = 0.78 and 0.86 for green and roasted coffee, respectively), water determined a decrease of bean hardness and a further decrease of the elastic modulus.

Cooking quality of faba bean after storage at high temperature and the role of lignins and other phenolics in bean hardening

Selected physical and chemical characteristics of faba beans ( Vicia faba L.) cv. Fiesta were studied after 12 months storage at 5, 15, 25, 37, 45 or 50 °C (±2 °C) in relation to the hard-to-cook phenomenon. In comparison with control (seeds stored at 5 °C), seeds stored at 15 and 25 °C demonstrated non-significant ( p⩽0.05) changes in most of the physical and chemical characteristics including hydration and swelling coefficients, acid detergent fibre, lignin and tannin contents, whereas seeds stored at ⩾37 °C demonstrated significant changes ( p⩽0.05). Solutes and electrolytes leaching after 18 h soaking substantially increased with increased temperature. Faba bean hardness tested by the hard-to-cook test also increased substantially with increased storage temperature. After 8 h soaking followed by 2 h cooking, the puncture force required for seeds stored at 5 °C was 3.3 N seed −1 whereas seeds stored at 50 °C required a much higher puncture force of 15.2 N seed −1. There was a high negative correlation ( r 2=0.98) between storage temperature and cooking ability of faba bean. Substantial increases in acid detergent fibre and lignin contents occurred with increased storage temperatures. There was a three-fold increase in lignin content of faba bean stored at 50 °C compared to those stored at 5 °C and it was correlated with bean hardness ( r 2=0.98). Storage at high temperatures for 12 months led to a substantial reduction in total free phenolics especially in the testa and there was a greater reduction with increasing storage temperature. Reduction in free phenolics was negatively correlated ( r 2=0.75) with bean hardness.

USE OF THE SHEAR PRESS FOR PROCESS DEVELOPMENT OF SUGAR-COATED BEANS

The main objective of this research was to investigate the possibility of using the shear press to develop an alternative isothermal process equivalent (in hardness) to a commercial process for sugar-coated beans. Control sugar-coated cranberry beans were processed according to a typical Japanese dynamic temperature process batch recipe (soak for 12 h at 23C, bring to 98C in 15 min, cook at 98C for 8 min, sugar cook in 50% sugar in water at 70C for 45 min). The treatment samples were processed isothermally (initial soak temperature 77C, then left to soak at 23C for 12 h; cook at 98C for 9, 10, 11, 12, 14 or 16 min; sugar-cook similar to the control sample) to conform to typical commercial bean-processing conditions. Bean hardness was measured using a Kramer shear press. On the basis of preliminary results, 11-min cook time treatment was chosen to determine if discriminatory panels could detect a difference in hardness between the control and treatment. The panelists could not detect a significant difference in hardness between the control and chosen treatment (95% confidence). The shear test may save cost and time for process development of sugar-coated beans.

Modelling textural changes during the hydration process of red beans

Hydration kinetics of red kidney beans were studied upon soaking at 20, 30, 40 and 60 °C by the method of weight gain. Texture (hardness) was measured instrumentally by cutting with a wedge-type blade mounted into an Instron Universal Testing Machine at a speed of 200 mm min −1. A logarithmic relationship was established between bean hardness and water absorption for the four soaking temperatures studied (p < 0.001). Rearranging the hydration kinetic model, the parameters controlling changes in moisture content during soaking were determined and, subsequently, the textural degradation in the bean structure. Bean hardness was modelled as a function of soaking time and temperature. The predictive capability of the model was examined and differences between experimental and predicted values were not significant at the 5% level (P > 0.05).

Azuki bean sizes and ama-natto preparation

Ama-natto is the Japanese name for cooked and sweetened whole beans. Studies were conducted to examine the effect of soaking four sizes of azuki beans ( Vigna angularis) for 10, 14 or 18 h, and cooking the soaked beans for 16, 20 or 25 min to prepare ama-natto. Studies also examined the effect of cooking four sizes of azuki beans for 40, 45, 50, or 55 min to prepare ama-natto. Small azuki beans soaked for 10 h were softer, and exhibited larger quantities of water imbibition and solids leached into the soaking solution than the large beans. When the soaking time was increased to 14 or 18 h, the differences in bean hardness and water imbibition among the four sizes of azuki beans were largely reduced. When raw azuki beans were cooked for 40 min, the hardness of cooked beans and ama-natto decreased with the decrease in bean size. The differences in hardness among the four sizes of cooked beans and ama-natto decreased when the cooking time of raw beans was increased from 40 to 55 min. Compared to the raw beans, the soaked beans required less cooking time to reduce differences in hardness among the four sizes of cooked beans and ama-natto. ©

THE ROLE of PHYTASE and LIGNIN IN DECORTICATED DRY BEAN (PHASEOLUS VULGARIS) HARDENING DURING STORAGE

The lignification-like mechanism and that involving phytic acid degradation by phytase were evaluated in the hard-to-cook phenomenon of decorticated Mala-wian white and red bean genotypes (Phaseolus vulgaris). Samples were stored under various temperatures (16C; 35C) aw; (0.55 aw; 0.85 aw) and time periods (4 and 8 months) compared to the control group (2C; 0.30 aw; zero months). Phytase activities (Pi), phytic acid, calcium and magnesium ions, water soluble pectic substances and lignin concentrations were determined spectrophoto-metrically. Elevated phytase activities and slight, but nonsignificant increase in lignin levels were produced in both bean genotypes maintained under adverse storage conditions for extended time periods. Positive correlations between phytase activities and cooked white bean hardness for the 4 month (r2= 0.844) (p ≤ 0.01) and 8 month (r2= 0.689) storage periods were found. Lignin content of red beans was significantly (p ≤ 0.01) correlated (r2= 0.669) with hardness for the extended (8 month) storage period. However, no clear relationships were found between lignin levels and the 4 month stored red (r2= 0.232) and white (r2= 0.210) bean hardness, and between lignin concentrations and the 8 month (r2= 0.232) stored white bean hardness. the mechanism involving phytic acid degradation appeared to be the dominant system influencing the hard-to-cook defect in the white, and to some extent the red bean genotypes for the storage period 0-8 months.

WATER ABSORPTION and SWELLING IN DRY BEAN SEEDS

A modified first-order reaction model composed of an initial linear phase followed by a diffusion-controlled phase closely predicted water absorption and swelling in several varieties of fresh and stored beans. Dehulling resulted in increased rates of water absorption, but equilibrium values for both water absorption and swelling were reduced as a result of elimination of the water held between the seed coat and the cotyledons as well as between the cotyledons. Swelling of de-hulled seeds was reduced initially, since the seed coat swells faster than the cotyledons in the initial stages of water uptake. Addition of carbonate salt to the soaking solution generally reduced water absorption and swelling. the hard-to-cook defect was manifested by reductions in the rates of water uptake and diminished effects of dehulling and salt soaking on water absorption and swelling. Water absorption was significantly and negatively correlated with cooked bean hardness.

STORAGE-INDUCED HARDENING IN 20 COMMON BEAN CULTIVARS

Twenty cultivars of common bean (Phaseolus vulgaris L.) varying in color and size were grown in three consecutive growing seasons at different locations and then stored for 6 months at 30°C/85% RH to induce hardening. Bean hardness was measured instrumentally following soaking and cooking. All cultivars increased in hardness during storage by a factor ranging from 1.54 to 2.47. Significant sources of variation in hardness included cultivar, environment and, largest, cultivar × environment interaction. Of the various chemical and physical tests conducted on beans before and after storage, those important in determining final hardness included fluorescence intensity (a predictor of a phenol polymerization-type reaction), phytate level, seed volume (larger cultivars hardened less) and water relationships (storage reduced the amount of bound water). The amount of water absorbed following storage was related to cultivar color, seed volume and hilum area but not seed coat thickness.

Hard‐to‐cook phenomenon in common beans‐ influence of growing location and hardening procedures

SummaryTwo accelerated hardening procedures (storage for up to 4 months, and soaking in acetate buffer for up to 5 h) for testing beans were examined and compared, so that new cultivars prone to the hard‐to‐cook (HTC) defect may be identified. Bean hardness was measured by means of the Mattson bean cooker, and by measuring puncture force. Two imporant common bean (Phaseolis vulgaris) cultivars were grown in two locations differing in soil Ca and Mg content. Those from the high Ca site had longer cooking times, which increased more rapidly on accelerated storage and in the soaking tests. The results of this preliminary study suggest that the acetate soak hardening procedure is worthy of further investigation as the basis of a rapid test for the presence of the hard‐to‐cook defect in new cultivars.

Relationship of Black Bean (Phaseolus vulgaris L.) Hardness to Total, Neutral and Soluble Fiber Contents of Stored Samples

Relationship of Black Bean (Phaseolus vulgaris L.) Hardness to Total, Neutral and Soluble Fiber Contents of Stored Samples

Fluorescence Intensity Indicates Bean Hardening

ABSTRACTFluorescence microscopy was used to measure the intensity of fluorescent emanation from the cut surface of uncooked bean cotyledons. This parameter correlated significantly with the hardness of soaked cooked beans determined by either compression force of whole beans or the probe force of cotyledons only. This relationship existed whether hardness resulted from varietal differences or elevated storage conditions. Similarly, a significant correlation was found between the fluorescence intensity of isolated cell wall material and bean hardness. These results led to the conclusion that the increase in fluorescence intensity in hard beans may have been due to the accumulation of phenolic compounds within the cell wall and that the procedure developed had potential as a quicker and simpler way to determine bean hardness.