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     

Quality changes during storage of sous vide cooked green beans (Phaseolus vulgaris)

 The acceptability and quality of sous vide cooked green beans (Phaseolus vulgaris) were investigated during chilled storage. A suitable heating procedure was established whereby 2.0-kg packages were heat processed at 90°C for 25 min, corresponding to an average pasteurization value, PV_70,10, of 14 min. During storage for up to 25 days at 3°C drip loss, pH, colour (Minolta L ^* a ^* b ^*), texture (Instron) and microbiological stability were examined and sensory characteristics evaluated by a trained sensory panel. No marked changes in texture, drip loss, pH or microbiological counts were observed but a change of colour from green to olive green was observed by both objective and sensory analyses. This detrimental change in colour, which had begun during the first week, was the limiting factor for shelf-life during storage. Subsequent reheating, however, resulted in further colour changes which partially obscured the initial differences observed during the storage period. Storage for more than 1 week resulted in undesirable quality changes in the odour and flavour of the green beans. Therefore, a maximum shelf-life of 8 days at 3°C was recommended. Inoculation trials showed that psychrotrophic Bacillus cereus were able to germinate and grow to levels of 10⁷ g^–1 in the packages at abuse temperatures (7°C and 17°C), whereafter numbers declined. Received: 21 April 1997     

Effect of pre-dehulling treatments on some nutritional and physical properties of navy and pinto beans (Phaseolus vulgaris L.)

The effect of pre-dehulling treatments using low and high temperatures on some nutritional and physical properties of navy and pinto beans was investigated. Beans were exposed to water (14%, 28% and soaking 1:5, w/v for 6 h, 16 and 16 h, respectively) to facilitate seed coat detachment prior to freeze drying (FD) for 48 h or heat drying (HT) for 20 or 60 min. Exposure to the highest moisture levels produced the largest seed coat yields (17.38-20.91%) and was independent of the drying conditions. The total phenolic content was positively correlated to the 1,1-diphenyl-2-picrylhydrazyl (DPPH) antioxidant activity and increased as the exposure time to HT increased, but it was unaffected by the FD. The nutritional properties of the bean varieties differed significantly, phytic acid was unaffected, and the highest antioxidant activity was observed on the seed coats of HT pinto beans (69.24-84.46% of DPPH discoloration). Significant physical changes were observed for the HT seeds, with the highest yellowness and the lowest peak viscosity detected in the soaked and HT (60 min) beans.     

Cellulose-based edible films and their effects on fresh beans and strawberries

 Cellulose-based edible films were applied to fresh beans and strawberries. The moisture loss from these food was measured following the application of films of varying composition under different conditions. The effects of the method of application of film solution, the amounts of polyethylene glycol (PEG), stearic acid (SA), palmitic acid (PA) and lauric acid (LA) in the film, the molecular weights of methyl cellulose (MC) and PEG and, finally, the relative humidity of the environment on moisture loss from fresh beans and strawberries coated with films were investigated. The brushing method for the application of film solution to the foods was found to be better than wrapping and dipping methods in terms of reducing the moisture loss. Recommended amounts of PEG-400 and fatty acids in film solution to reduce moisture loss from foods were found to be 11 ml and 40 g per 100 g MC-20000, respectively. A slight decrease in moisture loss was observed when PEG-400 and MC-20000 in the film solution were replaced by PEG-1000 and MC-41000, respectively. Finally, it was found that moisture loss from fresh beans and strawberries coated with films decreased as the relative humidity of the environment in which they were kept was increased. Received: 19 December 1996 / Revised version: 20 May 1997     

Comparison of high-performance liquid chromatography and spectrofluorimetry for vitamin C analysis of green beans (Phaseolus vulgaris L.)

 A spectrofluorimetric method and a chromatographic method [high-performance liquid chromatography – ultraviolet (HPLC-UV) detection] were compared for vitamin C analysis of green beans. For HPLC-UV, the determination was performed before [ascorbic acid (AA)] and after reduction with dithiothreitol [AA + dehydroascorbic acid (DHAA)]; for spectrofluorimetry, DHAA was determined after oxidation with activated charcoal. The fluorimetric determination of DHAA before oxidation was also carried out, and showed good precision but poor accuracy (very high recovery percentages). HPLC-UV showed better linearity and sensitivity, while spectrofluorimetry was more precise. Both methods were suitable for green bean samples, and the choice of which one to use depends on the particular interest of the analysis: spectrofluorimetry may be preferable when the total content of vitamin C is required, but not for individual analysis of each form. HPLC-UV is more suitable when the interest of the analysis is the ascorbic acid form as a deterioration index of vegetable products. Received: 29 March 1999 / Revised version: 12 May 1999     

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     

Relating consumer preferences to sensory and physicochemical properties of dry beans (Phaseolus vulgaris)

BACKGROUND: Dry beans (Phaseolus vulgaris) have a range of varieties, colours and sizes. Differences in physicochemical and sensory properties influence consumer choices for beans. This study related consumer preferences to sensory and physico‐chemical properties of selected bean varieties—Jenny, Kranskop, PAN 148, AC Calmont, PAN 150 and Mkuzi—grown in Mpumalanga (MP) and Free State (FS) in South Africa. RESULTS: Significant (P < 0.05) variety, location as well as location × variety interaction effects were found for both physico‐chemical and sensory properties of beans. Jenny‐FS, Mkuzi and PAN 148‐MP beans had relatively long cooking times (>60 min). Some beans (e.g. PAN 150 and Mkuzi beans) were described as bitter, soapy and metallic with a raw‐bean flavour whereas more preferred beans (e.g. Jenny‐MP, Kranskop‐MP) were sweet, soft and with a cooked‐bean flavour. CONCLUSION Apart from small seed size, sensory characteristics such as bitter taste, soapy and metallic mouthfeel and hard texture contributed to consumers' dislike of certain bean varieties. The sweet taste, cooked‐bean flavours, soft and mushy textures of the most accepted varieties seemed to be related to beans with good hydration capacities that facilitated softening during cooking. Copyright © 2007 Society of Chemical Industry     

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.     

Effect of natural and controlled fermentation on flatus‐producing compounds of beans (Phaseolus vulgaris)

Fermentation of grain legumes is an efficient method to reduce the concentration of α‐galactosidic compounds that are known to be flatulence producers. Soluble dietary fibre has also been implicated in flatulence production; however, little information exists about the effectiveness of fermentation in diminishing the effects of these compounds. The objective of this work was to study the effect of natural fermentation (NF) and controlled fermentation (CF) on the content of α‐galactosides and dietary fibre in dry beans (Phaseolus vulgaris) for 24, 48, 72 and 96 h. After 48 h, the pH during NF dropped from 6.15 to 4.00 and the nominal acidity increased six times; for CF, however, although the decrease in pH was similar to that for NF, the nominal acidity increased only three times after 48 h. Insoluble fibre content did not change the pH significantly after 96 h for NF and CF. Soluble fibre suffered an apparent removal after 48 h of NF and underwent a sharp reduction of 66% after 96 h of CF. The concentration of stachyose (the main α‐galactoside in raw beans) diminished notably after 48 h and 96 h NF (72% and 95% respectively), whereas with CF only 11% was removed after 96 h. NF of P vulgaris seems to be more effective than CF in reducing the flatulence‐producer factors (α‐galactosides and soluble dietary fibre). Copyright © 2003 Society of Chemical Industry     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.     

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     

Preparation and characterization of protein isolate from fresh and hardened beans (Phaseolus vulgaris L.)

ABSTRACT:  The purpose of the present work was to determine the effect of accelerated hardening of beans on yield and physicochemical, functional, and toxicological properties. Protein isolates were obtained from fresh and hardened common beans ( Phaseolus vulgaris L.). Acid treatment was an effective method to produce hardened bean. Protein recovery in the isolation procedure for fresh bean isolate (FBI) was 45.5% and 36.15% for hardened bean isolate (HBI); however, the amount of protein was similar in both isolates. In general, the amino acid pattern was similar in both isolates. Electrophoresis analysis showed that the main protein (phaseolin) remained unchanged during the isolation procedure. HBI showed a decrease in the bands of 14 to 26 kDa corresponding to the phytohemagglutinin group, and this was associated with a 56.6% decrease in the concentration of the trypsin inhibitor (TI). Heat treatment of FBI reduced 89.4% of the TI and the hemagglutining activities, and it was reflected in an adequate weight gain of young animals. FBI showed better functional properties than HBI, and both isolates showed the same amount of flavonoids.     

Postharvest treatments with radio frequency for 10 and 20 kg batches of black beans (Phaseolus vulgaris L.)

Radio frequency (RF) heating has been considered an alternative to conventional postharvest disinfestation methods in stored agricultural products. RF treatments at pilot scale (12 kW, 27.12 MHz) were applied in black beans (batches of 10 and 20 kg), until reach the target temperature for weevil mortality (50 °C). Temperature was held by 1 min, and then beans were cooled by forced air. During the protocol, the temperatures were followed by thermal images. For the 10 kg batch, the average heating time was 2.72 min, while for the 20 kg batch, only 1.29 min were required to reach the target temperature of 50 °C. This reduction in heating time is due to dielectric heating provides rapid and volumetric heating. Average cooling time was 14.75 and 26.75 min for batches of 10 and 20 kg respectively. The heating uniformity index values (λ) were close to zero (0.025 for 10 kg batch and 0.023 for 20 kg), indicating even heating. Water absorption capacity, density and viability of beans were not affected by the RF treatments (P > 0.05). Due to volumetric heating, better results were obtained for 20 kg batch, demonstrating the feasibility of RF technology for disinfestation purposes in relatively large batches of black beans.     

Potential for increasing the amounts of bioavailable zinc in dry beans (Phaseolus vulgaris L) through plant breeding

A whole‐body radioassay procedure was used to assess the bioavailability to rats of zinc (Zn) in seeds of 18 genotypes of beans (Phaseolus vulgaris L) that were grown hydroponically. Dry beans that were labelled intrinsically with ⁶⁵Zn were added to test meals fed to rats that were marginally Zn‐deficient. The amount of Zn in the seeds varied between genotypes and ranged from 26.7 to 62.4 µg g^?1 (from 0.41 to 0.95 µmol g^?1) dry weight (DW). Similarly, the amount of iron (Fe) in the beans varied nearly twofold (from 52.3 to 96.3 µg g^?1 DW), and Zn and Fe concentrations were positively correlated. Concentrations of myo‐inositolhexaphosphate (IP6) plus myo‐inositolpentaphosphate (IP5) varied from 18.1 to 27.3 µmol g^?1 DW. Cultivars with white‐coloured seeds contained relatively small amounts of tannins varying from 0.12 to 0.16 mg g^?1 DW (determined as catechin equivalents) compared to those with coloured seed coats (up to 2.58 mg g^?1 DW). All rats readily ate the test meals so that Zn intake varied directly with seed‐Zn concentration. As indicated by ⁶⁵Zn absorption, the bioavailability to rats of Zn in the seeds varied between genotypes and ranged from about 78 to 95% of the total Zn in the seeds. The bioavailability of Zn to marginally Zn‐deficient rats was not affected markedly by either IP5 + IP6 or tannin in the dry beans. These results demonstrate that the concentration of Zn in dry beans can be increased through traditional plant‐breeding techniques and that this may result in significant increases in the amount of bioavailable Zn in the beans. Increasing the amount of Zn in beans may contribute significantly to improving the Zn status of individuals dependent on beans as a staple food. © 2002 Society of Chemical Industry     

Thermal Effects on Net Protein Ratio of Red Kidney Beans (Phaseolus vulgaris L)

Net protein ratio (NPR), predicted-protein efficiency ratio (P-PER), relative NPR (RNPR), and corrected RNPR (CRNPR) of thermally processed red kidney beans were estimated in rats and compared to in vitro protein digestibility-corrected amino acid score (AAS_IVDP), and computed-protein efficiency ratio (C-PER). Thermal processing had a significant effect on protein intake, NPR, P-PER and CRNPR values of beans. Changes in protein intake suggest that heat processing had an effect on the palatability of the beans. Home-cooked beans and commercially canned beans had higher NPR values than beans autoclaved at 128°C for 20 min, while beans autoclaved at 121°C for 10–90 min had intermediate values. High correlation coefficients between P-PER and C-PER, CRNPR and C-PER, and CRNPR and AAS_IVDP (r=0·990, 0·992 and 0·960, respectively, P<0·001) were observed.     

Oxidative damage to proteolytic enzymes: inactivation of papain and ficin by ferrylmyoglobin

 Ferrylmyoglobin [MbFe(IV)=O], formed by activation of metmyoglobin by hydrogen peroxide, inactivates the cysteine proteinases papain (EC 3.4.22.2) and ficin (EC 3.4.22.3) more efficiently than hydrogen peroxide, but less efficiently than hydroxyl radicals as generated by peroxynitrite or the Fenton reaction. Metmyoglobin and oxymyoglobin could not inactivate papain and ficin. Oxidation of papain and ficin by ferrylmyoglobin occurs in enzyme/haem-protein complexes with binding constants of approximately 10⁵ l · mol^–1; inactivation of proteolysis by papain plateaus at neutral pH to about ¹/₃ whereas the inactivation under acidic conditions was larger. Received: 11 July 1997 / Revised version: 16 September 1997     

Oxidative damage to proteolytic enzymes: inactivation of papain and ficin by ferrylmyoglobin

 Ferrylmyoglobin [MbFe(IV)=O], formed by activation of metmyoglobin by hydrogen peroxide, inactivates the cysteine proteinases papain (EC 3.4.22.2) and ficin (EC 3.4.22.3) more efficiently than hydrogen peroxide, but less efficiently than hydroxyl radicals as generated by peroxynitrite or the Fenton reaction. Metmyoglobin and oxymyoglobin could not inactivate papain and ficin. Oxidation of papain and ficin by ferrylmyoglobin occurs in enzyme/haem-protein complexes with binding constants of approximately 10⁵ l · mol^–1; inactivation of proteolysis by papain plateaus at neutral pH to about ¹/₃ whereas the inactivation under acidic conditions was larger. Received: 11 July 1997 / Revised version: 16 September 1997     

The yield and quality of fresh and ensiled plant material from intercropped maize (Zea mays) and beans (Phaseolus vulgaris)

An investigation was carried out in the UK to determine whether intercropping with Phaseolus vulgaris beans increases the yield and nutritional quality of maize forage. Fresh and dry yields arising from different sowing dates and different densities of the two species were evaluated, with total nitrogen concentration (TNC) of the plants, and crude protein concentration (CPC), dry matter, metabolizable energy (ME), pH and starch, lactic acid and ash contents of ensiled material. Highest biomass yields of intercrops were obtained when the two species were planted simultaneously. There was a higher TNC in intercropped maize plants than in maize plants grown without beans (P < 0.05). Biomass yields were not significantly higher with a higher density of maize in the intercrop than with a lower density, nor were they higher with monocrop maize than with intercropping. However, the biomass had higher CPC at 75 000 maize plus 50 000 beans ha^?1 and 50 000 maize plus 50 000 beans ha^?1 than monocrop maize. Other nutritional characteristics of the silage made from the intercrop treatments were not significantly different from those of the silage made from monocrop maize. As the silage from intercrops of 75 000 maize plus 50 000 beans ha^?1 and 50 000 maize plus 50 000 beans ha^?1 gave more CP per land area than monocrop silage, and gave biomass yields that were not significantly different from monocrop maize, it was concluded that such intercropping is suitable for producing high‐quality silage under similar agro‐climatic conditions. Copyright © 2007 Society of Chemical Industry     

Resistant starch and potential glycaemic index of raw and cooked legumes (lentils, chickpeas and beans)

 The amount of resistant starch (RS) in raw and processed legumes, lentils, chickpeas and beans was analysed. In addition, the effect of cooking on the availability of legume starches to enzymes, which may influence the glycaemic response, was studied. Raw legumes were found to have higher RS values (16–21%) than retrograded or cooked ones (4–8%). Cooling increased RS yields, whereas reheating maintained or decreased the value depending on the sample. On the other hand, the kinetics of starch hydrolysis revealed that the rate of digestion was higher for cooked seeds and retrograded flours (15–21% of total starch digested) than for raw flours (5–8% of total starch digested). The estimated glycaemic indices (GIs), i.e. GI₁ from the Hydrolysis Index (HI) and GI₂ from the percentage of hydrolysis within 90 min (H ₉₀), were well correlated with the reported GI values (r = 0.96 and r = 0.95 respectively, P≤ 0.05). Received: 22 September 1997 / Revised version: 24 November 1997