Physico-chemical and enzymatic studies on acetylated protein isolates from faba beans (Vicia faba L.)

Selected physico-chemical properties of a faba bean protein isolate before and after being acetylated have been investigated using analytical ultracentrifugation, SE- and RP-HPLC, viscometry and hydrophobicity measurements using fluorescence probe techniques. The time course of relative chymotryptic hydrolysis rates was followed by means of the TNBS method and RP-HPLC analysis. The extensive decrease of the 11 S and 7 S protein components of the isolate in favour of a low molecular weight 2 S component after exhaustive acetylation is the proof of the dissociated state of the highly modified derivatives. Both the viscometric measurement and the study of proteolysis breakdown give arguments for a rather unfolded state both of the unmodified and the modified protein isolates. The course of relative chymotryptic hydrolysis rate points to a successive transition from a globular state into a more unfolded one depending on the degree of acetylation. Both the viscometric data and the hydrophobicity measurements revealed a conformational transition at about 60% N-acetylation. This level of modification corresponds to that where a sharp increase of OH-acetylation takes place.     

The relationship between maturity and quality of canned broad beans (Vicia faba L.)

Summary. This paper describes a co-operative investigation carried out by the Fruit and Vegetable Preservation Research Association and eight of its member firms to determine optimum maturity of broad beans for canning.
The results indicate that (a) there was no difference in flavour in canned broad beans harvested at tenderometer readings from 90 to 200, (b) there was a significant linear deterioration in texture as beans matured, (c) alcohol insoluble solids of raw and canned beans increased linearly as beans matured, (d) a linear relationship was found between tenderometer readings and sample size, (e) consumers equally preferred canned broad beans harvested at tenderometer readings of 120 and 160 and (f) optimum maturity of broad beans for canning from the data obtained was at a tenderometer reading of 136 using a 5 oz sample of raw beans.     

Limited tryptic hydrolysis of legumin from faba bean (Vicia faba L.): formation of an [unequal] subunit pattern

One-dimensional and two-dimensional SDS-PAGE and Hydrophobic Cluster Analysis (HCA) were used for investigating the course of limited tryptic hydrolysis of faba bean legumin. SDS-PAGE revealed the formation of an “unequal” subunit pattern, characterized by 30 and 50 kDa subunits, which could be related to the A- and B-type subunits of legumin. These subunits followed different pathways during the non-cooperative part of the tryptic hydrolysis. HCA revealed structural differences between the subunit types and gave arguments to predicted potential splitting sites. A- and B-subunits differ in extension and composition of the flexible segments as well as in the interior of the C-terminal side, as in the C-termini of the α-chains which confirmed the observed non-uniform hydrolysis pattern. The HCA plot demonstrated that the number and exposition of flexible surface elements was changed by limited hydrolysis. This result was discussed with regard to the influence of tryptic modification on the emulsifying properties of legumin.     

Phytate and total phosphorus content of field beans (Vicia faba L.)

Considerable variation was found in the phytate and total phosphorus contents of varieties, selections and genotypes of field beans (Vicia faba L.) The phytate phosphorus content of seeds taken from single plants of the variety Dacre indicated that large variations (1.93-4.03 g kg^?1), not significantly correlated with protein content, existed within an established variety. Although some variation in the ratio of phytate to total phosphorus was observed (0.40-0.60), highly significant correlation coefficients were obtained for total and phytate phosphorus contents. The significance of the results obtained is discussed in relation to the potential for improving the nutritive value of field beans by breeding for lower phytate content.     

Effects of micronising on the utilisation of field beans (Vicia faba L.) by the young chick

The major changes in the composition of field beans (Vicia faba L.) caused by micronising were as follows: the moisture content was reduced from 16.5 to 13.2%, the trypsin inhibitor activity reduced from 2.49 to 0.21 trypsin inhibitor units/mg dry matter and the available carbohydrate content raised from 40.6 to 50.2%. Growth and food consumption of broiler chicks from 1 to 2 weeks of age were not affected significantly when micronised beans replaced raw beans in their diets at a level of 300 g/kg. However, food conversion efficiency, apparent dry matter digestibility and nitrogen retention were significantly improved and pancreas size significantly reduced when the birds were fed the diet containing the micronised beans. The nitrogen-corrected metabolisable energy (m.e.) of the diet containing 500 g of micronised beans/kg (10.88 MJ/kg) was significantly higher than that of a diet containing 500 g of raw beans/kg (10.33 MJ/kg). It was calculated that the m.e. of the beans had been raised from 10.59 to 11.67 MJ/kg dry matter by micronisation. The improvement in nutritive value is attributed partly to the destruction of the trypsin inhibitor and partly to the increased availability of the carbohydrate fraction of the beans.     

Preparation of broad bean (Vicia faba L. minor) products Part 3. Pretreatment of broad beans and broad bean flour —processes and effects

For improving sensory, functional and other properties broad beans are pretreated in 3 different ways. The pretreatments include defatting or isoelectric washing of broad bean flour and hydrothermal treatment of whole dehulled broad beans. Every pretreatment process leads to particular advantages, described in this paper, although sensory improvements are found in all pretreated products.     

Relationships between adsorption and emulsifying of acetylated protein isolates from fabe beans (Vicia faba L.)

The influence of acetylation on surface adsorption and emulsifying properties of faba beans protein isolates (FBPI) was studied. Generally, acetylation improved the interfacial activity of FBPI. The plateau value of the Gibbs' adsorption isotherms measured with the Wilhelmy-plate was between 22.97 and 24.22 mN/m. The critical association concentration (CAC), i.e. the inflection point of the adsorption isotherms, was shifted from 2.06. 10^?5 to 5.35. 10^?7 g/ml with progressive acetylation. The dependence of the CAC on the degree of acetylation was found to be significant. For FBPI stabilized n-decane/water emulsions with varying volume fraction of oil (?) the emulsifying activity index increased from 166 to 593 m²/g whereas the droplet size decreased from 7.79 to 3.4 μm with acetylation. The correlation between emulsifying activity of FBPI and both degree of acetylation and adsorption behaviour was only significant for emulsions with ? 0.4.     

Cellulase inhibition by tannins in the testa of field beans (Vicia faba)

The testa of field bean varieties with coloured flowers contained 4–8 % tannin (measured as total phenolics) compared with less than 0.6 % in the testa of white flowered varieties. The tannin present in whole beans was almost entirely contained in the testa. The presence of high levels of tannin reduced in vitro digestibility and solubility in cellulase solutions of the testa and addition of high tannin testa decreased the solubility of cotyledon protein in acid pepsin. Water extracts of the testa from coloured-flower varieties inhibited the action of fungal cellulase and reduced the in vitro digestibility of white flowered testa and cellulose. A highly significant relationship (r= ?0.93***) was found between the tannin content and solubility in cellulase of testa for a range of 24 varieties. It is concluded that the effect of testa tannins on in vitro digestibility can be mainly attributed to their effect on cell wall digesting enzymes rather than an effect on protein solubility per se.     

Gelation of a broad bean (Vicia faba L. minor) protein fraction (prepared at pH 2) in dependence on some influencing factors

A protein fraction is prepared from broad bean protein isolate at pH 2 which forms gels in the acid pH range. The gels are fluid at high temperature and become strength when cooling. The gel strength increases with increasing pH, with increasing heat treatment, and with increasing protein concentration. Addition of calcium and dextrose sirup increases the gel strength whereas sucrose decreases it. The transparency of the gels decreases with increasing pH.     

Variation in the oil content and fatty acid composition of field beans (Vicia faba) and peas (Pisum spp.)

Oil content has been found to range from 1.2–1.9% in a wide range of diverse field bean (Vicia faba) cultivars, populations and selections and from 1.4–2.8% in a narrower range of pea cultivars. The ranges in fatty acid composition for beans and peas respectively were palmitic, 13.9–21.0% and 12.0–16.6%, stearic 2.2–3.5% and 2.5–4.2%, oleic 15.0–33.0% and 14.2–33.3%, linoleic 41.3–59.7% and 43.7–60.9%, linolenic 2.6–4.9% and 6.4–13.4%. Environment exerted a significant effect on the oil content of field beans but cultivar differences remained apparent. The analysis of whole or milled field beans stored for up to 5 years showed only minor losses of oil and component fatty acids. In both species over 90% of the total oil content was found in the cotyledons. Cultivar differences in whole grain oil content were associated with the concentration of oil in the cotyledons and appeared independent of the relative proportions of either embryo or seed coat. The interrelationships between oil content and other seed characteristics were also determined and the significance of these results in relation to plant breeding are discussed.     

Fractionation of plant material. IV.—Distribution of amino acid residues in fractions obtained from leaves of broad bean (Vicia faba L.)

The quantitative distribution of amino-acid residues amongst some fractions derived from broad-bean leaves was determined. Among the free amino acids, asparagine predominated and 3,4-dihydroxyphenylalanine (DOPA) was abundant. DOPA was absent from the protein fractions. Aggregated N recovery and amino acid composition resembled those found for leafy materials by previous workers. Material extracted by ethanol from the TCA-precipitated fraction resembled the bulk protein in molecular size and amino acid composition. A fraction not migrating during electrophoresis in phenol-acetic acid-water gave, on hydrolysis, amino acids presumed to be bound in neutral or weakly acid compounds, mostly of low molecular weight.     

Effects of limited enzymatic hydrolysis with trypsin on the functional properties of hemp (Cannabis sativa L.) protein isolate

Effects of limited enzymatic hydrolysis induced by trypsin on the physicochemical and functional properties of hemp (Cannabis sativa L.) protein isolate (HPI) were investigated. The enzymatic hydrolysis was confirmed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography (SEC). SEC and differential scanning calorimetry (DSC) analyses confirmed the presence of aggregates in the corresponding hydrolysates (with the degree of hydrolysis of 2.3–6.7%). Functional properties, including protein solubility (PS), thermal properties, emulsifying and foaming properties, and water holding and fat adsorption capacities (WHC and FAC) were evaluated. The PS was remarkably improved by the limited enzymatic hydrolysis at all tested pH values. However, the enzymatic hydrolysis led to the marked decreases in emulsifying activity index, foaming capacity and foam stability, WHC and FAC. These decreases were to a great extent related to the presence of aggregates in the hydrolysates.     

Varietal variation in the anti-nutritive effects of field beans (Vicia faba) when fed to rats.

Testa and cotyledons were separated from white and coloured flowered varieties of field beans (Vicia faba) and incorporated into complete diets for rats. Diets containing 10% testa from the coloured variety caused a 15% reduction in live weight gain compared with the diets containing testa from the white flowered variety. This was accompanied by a reduction in the true digestibility of nitrogen and the apparent digestibility of carbohydrates and lipids. The protein efficiency ratio and the net protein utilisation were also reduced but the biological value of protein was not significantly affected. The efficiency of utilisation of ingested feed dry matter was significantly reduced for the diets containing coloured flower testa but when live weight gain was expressed as a fraction of ingested digestible dry matter there were no significant differences. Live weight gain and digestibility of organic matter components were highly negatively correlated with the total phenolic content of the diet. It was concluded that the reduction in live weight gain of animals fed diets containing testa of a coloured variety compared with that of a white flowered variety was caused mainly by the reduction in digestibility of organic matter brought about by the complexing of dietary and digestive enzyme proteins by the high content of phenolic compounds present in the testa of the coloured variety. A 10% reduction in live weight gain was recorded for animals consuming diets containing cotyledons of coloured varieties compared with those consuming white flowered cotyledons. This reduction was not accompanied by any change in the digestibility of organic matter components and the true digestibility of nitrogen and protein efficiency ratio were not significantly different. There was, however, a significant reduction in the biological value which was a result of increased urinary nitrogen output. It was concluded that the cotyledons of the coloured flowered variety contained an anti-nutritive factor which was not a tannin-like compound and which had an effect on the protein metabolism of the animal.     

A modified procedure for the purification of vicine and convicine from fababeans (Vicia faba L.)

A procedure was developed for the simultaneous isolation of pure vicine [2,6-diamino-4,5-dihydroxypyrimidine 5-(β-D glucopyranoside)] and convicine [2,4,5-trihydroxy-6-aminopyrimidine 5-(β-D glucopyranoside)] from dehulled fababeans. The procedure involved the extraction of the glycosides with an ethanol-water (70:30, by vol.) solution, concentration of the extract to a minimal volume and adjustment of the pH of the aqueous extract to 7.2. Mixed vicine and convicine crystals, which were formed over a period of from 1 to 4 days, were harvested by centrifuging and washed with water and ethanol. Vicine was readily obtained from the mixed crystals by extraction at a low pH and recrystallised by adjustment of the pH to neutrality. Convicine, which is relatively insoluble in an acidic medium, was solubilised in an alkaline solution and recrystallised at a neutral pH.     

Cultivar identification of Vicia faba (L.) by sodium dodecyl sulphate–polyacrylamide gel electrophoresis of seed globulins

The globulin fraction isolation from Vicia faba seeds of different cultivars and different lines of the same cultivar has been examined by sodium dodecyl sulphate-poly-acrylamide gel electrophoresis (SDS-PAGE). The technique separates the globulin polypeptides into three distinct groups, termed A, B and C, with molecular weights above 46 kD, between 30–40 kD and below 26 kD, respectively. Distinct differences between polypeptide patterns of the different cultivars and of the different lines of the same cultivar were observed in groups A and B, little variation occurred in group C. Gradient zonal isoelectric precipitation was used to separate the globulin fraction of different cultivars into vicilin and legumin. Variation in polypeptide composition between cultivars was observed in both vicilin and legumin following SDS-PAGE. No difference between cultivars was detected in group C polypeptides of legumin.     

Preparation of broad bean (Vicia faba L. minor) products Part 4. Effects of recirculation of waste water on the quality of protein isolates

The isolation of proteins from broad bean flour is a water consuming process. The waste water of that consists of the supernatants after the isoelectric precipitation and washing. Different parts of those supernatant were recirculated into the process of protein extraction and isolation. The results show the possibility to recirculate 25% of the supernatant after the isoelectric precipitation and 100% of the supernatant after washing without any effect on the composition of the protein isolates.     

Amino Acid Composition of Protein Fractions Extracted from Phaseolus Beans and the Field Bean (Vicia faba L.)

Protein fractions were extracted sequentially with 2% sodium chloride, 30% isopropyl alcohol, 4% lactic acid and 0.5% potassium hydroxide from three varieties of adzuki beans, kafae and red kafae bean, three varieties of lima beans and red lima bean, two varieties of kidney beans and field bean that were grown in the tropics and sub-tropics. The sodium chloride extract had the highest range of protein concentration (51.2 to 81.4%). The sodium chloride extract was separated into two fractions based on solubility in water. The amino acid compositions of the flour from the seed and of the two fractions from the sodium chloride extract were determined. High contents of lysine, aspartic acid, glutamic acid and leucine were obtained, whereas the sulphur-containing amino acids contents were low.