The impact of processing on phytic acid,in vitro soluble iron and Phy/Fe molar ratio of faba bean (Vicia faba L.)

BACKGROUND: Faba bean is one of the important legumes in Asian countries. It is also a major source of micronutrients in many rural areas. Unfortunately, the bioavailability of iron from faba bean is low because it is present as an insoluble complex with food components such as phytic acid. The influence of soaking, germination and fermentation with the expectation of increasing the bioavailability of iron was investigated. RESULTS: Fermentation treatments were most effective in decreasing phytic acid (48–84%), followed by soaking at 10 °C after preheating (36–51%). Steeping faba beans for 24 h at 25 °C had the least effect on the removal of phytic acid (9–24%). With increased germination time at 30 °C, phytic acid progressively decreased from 9 to 69%. Most wet processing procedures, except soaking after wet preheating, caused losses of dry matter and iron (8–15%). In vitro iron solubility, as a percentage of total iron in soaked faba bean after dry preheating, was significantly higher than in raw faba bean (P < 0.05). Fermentation and germination did not have significant effects on the solubility of iron. CONCLUSION: The expected improvement of iron bioavailability levels due to lower phytic acid was not confirmed by increasing levels of in vitro soluble iron. Soaking, germination and fermentation can decrease phytic acid in faba bean. However, results from in vitro solubility measurement of iron showed little improvement of iron bioavailability in fermented and germinated faba beans over untreated raw faba beans (P < 0.05). It seems that componets of dietary fibre other than phytic acid are more important in binding iron. Probably, a complex association between dietary fibre and iron is the reason for the poor bioavailability of iron in faba bean. Copyright © 2009 Society of Chemical Industry     

Effects of various phytase sources on phytic acid content,mineral extractability and protein digestibility of tarhana

Changes in phytic acid (PA), HCl-extractability (HCl-E) of some minerals and in vitro protein digestibility (IVPD) during the production of tarhana prepared with the addition of different phytase sources (bakers’ yeast, barley malt flour and microbial phytase) were investigated. PA content of tarhana decreased significantly (p < 0.01) after addition of the yeast, malt and phytase. With respect to wheat flour used as raw material, PA content of tarhana decreased by 95.3%. After tarhana production, average values of HCl-E of Ca, Mg, Zn and K, and also IVPD of tarhana increased up to 80.2%, 86.4%, 73.9% and 92.6%, and 91.9%, respectively. Significant negative correlation coefficients were found between the PA and HCl-E of the minerals, and also IVPD. Tarhana production processes, including fermentation, drying and grinding, were able to remove the antinutritional effects of PA. Each one of the phytase sources used alone decreased the PA content to a limited extend. The results show that tarhana has good potential in the total amounts and bioavailability of the minerals and proteins.     

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 (r²=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 (r²=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 (r²=0.75) with bean hardness.     

Physical and functional characteristics of selected dry bean (Phaseolus vulgaris L.) flours

Many varieties of dry beans (Phaseolus vulgaris L.) are available with entirely different physico-chemical and sensory characteristics. Selected dry bean varieties (red kidney, small red kidney, cranberry and black) were processed into flour and analyzed for the physico-chemical and functional characteristics. The bulk density of the beans flours varied significantly (p < 0.05) from 0.515 g/ml for black bean flour to 0.556 g/ml for red kidney bean flour. The small red kidney bean flour had the highest water absorption capacity (2.65 g/g flour) while black bean flour showed the lowest at 2.23 g/g flour. Significant differences were observed for oil absorption capacities of bean flours, which ranged from 1.23 g/g for small red kidney bean flour to 1.52 g/g for red kidney bean flour. The bean flours emulsion capacity and stability and foaming capacity and stability also varied significantly and was variety-dependent. The highest apparent viscosity, 0.462 Pa.s, was recorded for small red kidney bean flour whereas black bean flour exhibited the lowest value of 0.073 Pa.s at 30 g/100 ml water content in the flour dispersions. The force-deformation curves for doughs from different bean flours showed that black bean flour had the highest peak force or hardness value of 90.7 N followed by doughs from cranberry, small red kidney and red kidney bean flours. The results of this study offer useful data on bean flours' potential uses in different food products.     

Fermentation and enzyme treatment of tannin sorghum gruels: effects on phenolic compounds,phytate and in vitro accessible iron

The presence of polyphenols and phytate in cereal products has been shown to interfere with the bioavailability of minerals such as iron. In the present study, we added enzymes (wheat phytase and mushroom polyphenol oxidase) during fermentation of tannin sorghum gruels prepared from flour with or without addition of 5% flour of germinated tannin-free sorghum grains (power flour), and investigated the effects on phenolic compounds, phytate and in vitro accessible iron. Assayable phenolic compounds were significantly reduced by fermentation, with high reductions observed in gruels with added enzymes. Fermentation of the gruels with addition of enzymes reduced (on average) total phenols by 57%, catechols by 59%, galloyls by 70% and resorcinols by 73%. The phytate content was significantly reduced by fermentation (39%), with an even greater effect after addition of power flour (72%). The largest reduction of phytate (88%) was, however, obtained after addition of phytase. The in vitro accessible iron was 1.0% in the sorghum flour and it increased after fermentation with power flour and/or with enzymes. The highest in vitro accessibility of iron (3.1%) was obtained when sorghum was fermented with addition of power flour and incubated with phytase and polyphenol oxidase after the fermentation process.     

Use of low-temperature extrusion for reducing phytohemagglutinin activity (PHA) and oligosaccharides in beans (Phaseolus vulgaris L.) cv. Navy and Pinto

Bean (Phaseolus vulgaris L.) lectins and oligosaccharides are the anti-nutrients that limit dry bean consumption. The objective of this study was to study the effects of low temperature (85 °C) extrusion and steam-cooking (82 °C) on the fate of lectin, analysed as phytohemagglutinin activity (PHA), and the oligosaccharides, raffinose and stachyose. Both extrusion processing and steam-cooking significantly (p ? 0.05) reduced the lectin in bean flour by 85–95% over raw bean flours (control). The stachyose content in extruded navy bean flours was comparable to that in raw and steam-cooked flours while extruded pinto bean flour had significantly lower stachyose content than that found in raw and steam-cooked flour. The raffinose content of both navy and pinto extruded flours, though lower than raw bean flours, was significantly higher than that in steam-cooked flours. The results of this study demonstrated that extrusion processing at relatively lower temperature can be effective in eliminating lectins and reducing oligosaccharides.     

Nutrients and antinutritional factors in faba beans as affected by processing

 The influence on the nutrients content (soluble sugars, starch, dietary fibre and calcium) and antinutritional factors (α-galactosides and phytic acid) of faba beans (Vicia faba, L. major) of soaking in different solutions (distilled water, citric acid, and sodium bicarbonate solutions), cooking the presoaked seeds, dry-heating and germination have been studied. Soaking brought about a decrease in starch, sucrose, fructose, α-galactoside, dietary fibre and calcium content. Glucose was detected in soaked faba beans and soaking did not modify the phytic acid content. Cooking the presoaked faba beans produced a slight decrease in starch, and caused a general drop in α-galactosides, dietary fibre, calcium and phytic acid, with the exception of seeds presoaked in sodium bicarbonate in which cooking did not cause any appreciable changes in comparison with the unprocessed faba beans. Germination caused a sharp reduction in α-galactoside and phytic acid content after 6 days, whilst starch and dietary fibre decreased slightly. Calcium, however, enjoyed a slight increment during germination which was related to the decrease in the content of hemicellulose and phytic acid. Dry-heating caused a noticeable reduction in all the nutrients and antinutritional factors investigated. Of all the treatments studied, germination appears to be the best processing method to obtain nutritive faba bean flour, since it caused a minor decrease in starch content (15% loss), the largest α-galactoside and phytic acid removal (94% and 45%, respectively) and provided an appreciable amount of dietary fibre. Received: 21 December 1997 / Revised version: 19 February 1998     

Effects of polyphenol oxidation on in vitro iron availability in faba bean (Vicia faba L.) flour

Tannic acid (TA) and green tea extract (GTE) were added to faba bean flour, before and after incubation with polyphenol oxidase (mushroom tyrosinase), and the effect on in vitro iron availability was investigated. The inhibitory effect of TA and GTE was dose dependent, and the in vitro iron availability decreased from 64.5% in the pure faba bean flour to 9.8% (P < 0.05) with the addition of 1 mg of TA 1 g^?1 to faba bean flour. The addition of 5 mg of GTE resulted in low in vitro iron availability as after the addition of 10 mg of TA (11.6% against 10.3% for 1 mg TA). Incubation of the polyphenols with tyrosinase before addition to the faba bean flour significantly increased the in vitro iron availability. The increase in iron availability was significant (P < 0.05) when amounts of 0.2, 0.5 or 1 mg g^?1 TA or GTE added to faba bean flour, respectively, were oxidised, even with the lowest amount of tyrosinase (150 u). Oxidation of 1 mg TA or GTE with 150 u tyrosinase increased the in vitro iron availability from 10.3% to 15.5% and from 19.2% to 26.1%, respectively. At the 300‐u level, the addition of higher amounts of enzyme (from 600 to 900 u) did not have any effect. The results from the study therefore suggest that the oxidation of polyphenols may be a promising way to increase the availability of iron in polyphenol‐containing legume foods.     

Effect of Several Germination Treatments on Phosphatases Activities and Degradation of Phytate in Faba Bean (Vicia faba L.) and Azuki Bean (Vigna angularis L.)

Abstract: Two assays were conducted to investigate the changes of faba bean (Vicia faba L.) and azuki bean (Vigna angularis L.) phosphatases (phytase [Phy] and acid phosphatase [AcPh]) and the degradation of its substrates (inositol phosphate esters) during seed germination. The 1st assay was to establish the optimal germination conditions of faba bean and azuki bean to improve the endogenous phosphatases and increase the hydrolysis of phytate and, in the second assay, to determine the different lower phosphate esters of myo‐inositol produced during the germination process. In the 1st assay, seeds were soaked for 12 and 24 h and germinated for 3 and 5 d with and without the addition of gibberellic acid (GA₃). In the second assay, seeds were soaked for 12 h and germinated for 1, 3, and 5 d with GA₃. Phy (up to 3625 and 1340 U/kg) and AcPh (up to 9456 and 2740 U/g) activities, and inositol hexaphosphate (IP6) (8.23 and 7.46 mg/g), inositol pentaphosphate (IP5) (0.55 and 0.82 mg/g), and inositol tetraphosphate (IP4) (0.26 and 0.01 mg/g) were detected in ungerminated faba bean and azuki bean, respectively. The germination process caused a significant increase of Phy and AcPh activities in faba bean (up to 147% and 210%) and azuki bean (up to 211% and 596%) and a reduction in the phytate phosphorus content (up to 81% and 63%, respectively). Phytate phosphorus content was affected only by soaking time in the case of faba bean. Finally, during the course of germination, IP6 and IP5 were rapidly degraded in faba bean (88% and 39%) and azuki bean (55% and 56%), and IP4 was only a short‐living intermediate, which was increased during hydrolysis and degraded to inositol triphosphate. In this manner we could obtain a low‐phytate, endogenous phosphatase‐rich ingredient for enhancing human nutrition.     

Shelf stability and sensory properties of flour tortillas fortified with pinto bean (Phaseolus vulgaris L.) flour: Effects of hydrocolloid addition

To flour tortillas formulations containing 25 g/100 g of pinto bean flour, 0.5 g/100 g and 0.75 g/100 g of guar gum and sodium carboxymethyl cellulose (CMC) were added and their shelf stability was studied at 4 and 25 °C over 7 days. Texture, determined instrumentally, rollability, and water holding capacity were the main parameters studied. Selected samples were evaluated by 55 participants to determine consumer acceptability. Firmness and cohesiveness were negatively affected by the addition of bean flour, however, this effect was partially overcome by the addition of hydrocolloids. Guar gum had a positive significant influence on water holding capacity and texture over time (P < 0.001), while CMC had no positive effects. Despite the instrumental texture data, which showed that bean tortillas had inferior attributes than the wheat control, consumers found the overall texture and acceptability of bean tortillas with and without guar gum on the range of “like very much” and “like moderately”, which was significantly higher than the wheat control (P < 0.01). Based on physical and sensorial properties it would appear that these foods are industrially feasible and highly acceptable by health-conscious consumers.     

Chemical composition,dietary fibre and resistant starch contents of raw and cooked pea,common bean,chickpea and lentil legumes

The chemical composition and the contents of resistant starch and soluble and insoluble dietary fibre of pea (Pisum sativum L.), common bean (Phaseolus vulgaris L.), chickpea (Cicer aretinum L.) and lentil (Lens culinaris Med.) legumes, were studied. Raw and freeze-dried cooked samples were used, both in the form of flour. Protein values of the legumes ranged from 18.5 to 21.9 g/100 g for the raw grains and from 21.3 to 23.7 g/100 g for freeze-dried cooked legumes. Chickpea stood out for the highest lipid content (p < 0.05), the lowest insoluble fibre values, and soluble dietary fibre not detected. The average content of resistant starch found in the legumes did not differ statistically (p > 0.05), being 2.23 ± 0.24 g/100 g for freeze-dried cooked legumes, and showing a slight reduction in comparison to the raw form.     

Hydrochloric acid extractable minerals and phytate and polyphenols contents of sprouted faba and white bean cultivars

Two faba bean (Hudieba-72 and Bsabir) and three white bean (Serge, Giza and RO21) cultivars were sprouted for 6 days. The sprouted grains were dried and milled. Phytic acid and polyphenols contents and hydrochloric acid (HCl) extractability of minerals from the malt flours were determined at intervals of 2 days during sprouting. Phytic acid and polyphenols contents decreased significantly (P ? 0.01) with increase in sprouting time with concomitant increase in HCl extractable major and trace minerals. The contents of both major and trace minerals were slightly increased with sprouting time. When faba bean seeds were sprouted for 6 days, Bsabir had higher extractable Ca, while Hudieba-72 had higher P, whereas Fe and Mn recorded high level in Hudieba-72. When white bean seeds were sprouted for 6 days, RO21 cultivar had higher extractable Ca, while Giza-3 cultivar had higher P, whereas Fe and Mn recorded high levels in Serge and RO21 cultivars, respectively. There was a good correlation between phytate and polyphenols reduction and increase in extractable minerals with increase in sprouting time for all cultivars.     

Effects of Phytases and Dehulling Treatments on In Vitro Iron and Zinc Bioavailability in Faba Bean (Vicia faba L.) Flour and Legume Fractions

ABSTRACT: In vitro digestions were performed on faba bean flours with decreased phytate contents and on 2 dephytinized or nondephytinized faba bean fractions, a dehulled faba bean fraction, and a hull fraction with low and high fiber and tannin contents, respectively. In vitro bioavailability iron and zinc was defined as the relative amount of iron and zinc that became soluble after enzymatic treatment. Faba bean samples were sequentially digested with enzymes, including amylase, pepsin, pancreatin, and bile, under certain conditions following the enzymatic degradation procedure. Iron and zinc in vitro bioavailability of whole faba bean flours were significantly improved by phytate degradation, even if the phytate were not all degraded. Total dephytinization of dehulled faba bean led to an obvious increase in iron and zinc in vitro bioavailability, but that of hulls had no effect on either iron or zinc in vitro bioavailability. Fibers and tannins other than phytate are more important in chelating a high proportion of iron and zinc in faba bean hulls.     

Air classification of flours of three legume species: Fractionation of protein

The effect of changing the cut point of a laboratory air classifier on the protein fractionation into the fines was studied on the flour of two varieties each of cowpea (Vigna unguiculata), faba bean (Vicia faba) and pigeonpea (Cajanus cajan). Of the three species, the highest fines protein content (56.5–62.7% Nx6.25 over the range of cut points studied) and protein recovery (44.2–86.5% over the range) was for one variety of faba bean. The other variety of faba bean showed lower values. Fines from cowpea and pigeonpea flour contained protein contents in the range 26.5–46.8%, depending on cut point, with protein recoveries of 28.3–63.5%. Plots of dry weight yield vs. protein content of fines indicate that once the relationship between these two parameters has been established for a given species (or, in the case of faba bean, for variety), then the protein content of fines can be predicted from dry weight yield.     

Content of zinc,iron and their absorption inhibitors in Nicaraguan common beans (Phaseolus vulgaris L.)

Common bean (Phaseolus vulgaris L.), the staple crop of Nicaragua, provides protein and nonhaem iron, but inhibitors such as phytate may prevent absorption of iron and zinc by the consumer. Warehouses in Nicaragua do not have controlled atmospheres, so beans are exposed to high temperatures and humidities that may accelerate quality loss. To evaluate the impact of 6 months of storage on quality, four national accessions of common bean were submitted to two treatments, a conventional warehouse with uncontrolled temperature and humidity, and accelerated ageing at 40 °C and 75% RH. Iron content was 61–81 mg/kg of which 3–4% was bioavailable, and zinc content was 21–25 mg/kg, of which 10–12% was bioavailable. Bioavailability generally increased in storage, significantly so in year-old INTA Linea 628 in accelerated ageing. The concentration of phytate was 8.6–9.6 mg/g and it contained 54–63% of the total phosphorus. Improvement in bioavailability of divalent cations is needed.     

Effects of phytase,cellulase and dehulling treatments on zinc in vitro solubility in faba bean (Vicia faba L.) flour and seed fractions

Simulations of gastro‐intestinal digestion was used to try to identify the nature of the complexes between antinutritional factors and zinc in faba bean fractions. In the hull fraction, the action of phytases and the simultaneous action of cellulase and phytase allowed about 7% and 35% additional zinc to be solubilised, respectively. Single enzymatic degradation of phytates from dehulled faba bean allowed solubilisation from 65% to 93% of zinc depending upon the treatment. The zinc of faba bean flour was mainly linked to phytates and the greater the degree of phytate degradation before in vitro digestion, the greater the quantity of zinc released. In dehulled faba bean zinc was almost exclusively chelated by phytates. In the hull of faba bean, the majority of zinc was chelated in complexes between phytates and fibres.     

Effect of extrusion conditions on physicochemical and sensorial properties of corn-broad beans (Vicia faba) spaghetti type pasta

Corn-broad bean spaghetti type pasta was made with a corn/broad bean flour blend in a 70:30 ratio, through an extrusion-cooking process (Brabender 10 DN single-screw extruder with a 3:1 compression ratio). The effect of temperature (T = 80, 90 and 100 °C) and moisture (M = 28%, 31% and 34%) on the extrusion responses (specific consumption of mechanical energy and pressure) and the quality of this pasta-like product (expansion, cooking-related losses, water absorption, firmness and stickiness) was assessed. The structural changes of starch were studied by means of DSC and XRD. The extrusion-cooking process, at M = 28% and T = 100 °C, is appropriate to obtain corn-broad bean spaghetti-type pasta with high protein and dietary fibre content and adequate quality. The cooking characteristics and resistance to overcooking depended on the degree of gelatinisation and formation of amylose–lipid complexes. The critical gelatinisation point was 46.55%; beyond that point, the quality of the product declines.     

Extrusion of a hard-to-cook bean (Phaseolus vulgaris L.) and quality protein maize (Zea mays L.) flour blend

Heated extrusion was tested as an alternative process for incorporating “hard-to-cook” beans into food products. A 3² factorial design was used to evaluate extrusion conditions for a 40/60 (w/w) blend of “hard-to-cook” beans and quality protein maize. Tested extrusion variables were temperature (155, 170 and 185 °C) and moisture content (15.5, 17.5 and 19.5 g/100 g). Screw speed was fixed at 130 rpm. The extrudates obtained at 155 and 170 °C with 15.5% moisture had the best physical characteristics and were chosen for comparative analysis of nutritional changes between the unprocessed “hard-to-cook” bean/quality protein maize flour blend and the resulting extrudates. In vitro protein digestibility was higher in the extrudates (80%) than in the flour blend (76%). In vitro starch digestibility was higher at 155 °C (89%) and 170 °C (92%) than in the flour blend (12%). Processing conditions decreased dietary fibre content by 38% at 155 °C and 44% at 170 °C.     

The trypsin inhibitors present in seed of different grain legume species and cultivar

Trypsin inhibitors in a selection of grain legume seeds from different species and cultivars were studied. The results showed that trypsin inhibition content ranged from negligible in Lupinus spp. to very high in Glycine max. Although there is variation among cultivars, generally the highest TIU mg⁻¹ sample values occured in soybean (43–84) and common bean (21–25). Inhibitor content of different Lathyrus cultivars, ranged from 19–30 TIU mg⁻¹ sample. This was higher than the contents in chickpea (15–19 TIU mg⁻¹ sample) and pea (6–15 TIU mg⁻¹ sample). Lentil and faba bean had low values in most cvs (3–8, and 5–10 TIU mg⁻¹ sample, respectively). Trypsin inhibitor isoform analyses showed that the amount of TI detected, varied with legume species and variety.     

Folate content in processed legume foods commonly consumed in Egypt

Industrial food processing and household cooking are reported to affect folate content. This study examined the effects of industrial and household processing methods on folate content in traditional Egyptian foods from faba beans (Vicia faba) and chickpeas (Cicer arietinum). Overnight soaking increased folate content by ∼40–60%. Industrial canning including soaking, blanching and retorting did not affect folate content (p = 0.11) in faba beans, but resulted in losses of ∼24% (p = 0.0005) in chickpeas. Germination increased folate content 0.4–2.4-fold. Household preparation increased the folate content in germinated faba bean soup (nabet soup) one-fold and in bean stew (foul) by 20% (p < 0.0001). After deep-frying of falafel balls made from soaked faba bean paste, losses of 10% (p = 0.2932) compared with the raw faba beans were observed. The folate content (fresh weight) in the traditional Egyptian foods foul and falafel and in the beans in nabet soup was 30 ± 2, 45 ± 2 and 56 ± 6 μg/100 g, respectively. The traditional Egyptian foods foul, falafel and nabet soup are good folate sources and techniques like germination and soaking, which increase the folate content, can therefore be recommended.