Toxicological evaluation of acetylated faba bean globulin

Acetylated faba bean globulin (acVFG, acetylation degree 97%) was evaluated toxicologically in a subchronic feeding study and a female fertility test. Groups of male and female rats received acVFG in their diet at levels of 20, 40 and 80 g kg⁻¹ for 3 months. Additional groups were fed a commercial diet or given food containing 38 or 75 g kg⁻¹ casein. The subchronic toxicity study revealed growth retardation in both sexes at the 80 g kg⁻¹ acVFG level. The food consumption was reduced in males at 40 and 80 g kg⁻¹ acVFG and in females at 80 g kg⁻¹ acVFG. Histopathological alterations in the ovaries were observed at dietary levels of 40 and 80 g kg⁻¹ acVFG. Histopathological changes and decreases in the absolute and relative weight of the uterus were found in all groups fed acVFG. Therefore a no‐observed‐effect level (NOEL) was not derivable. Feeding females 80 g kg⁻¹ acVFG resulted in diminished pre‐implantation losses but increased post‐implantation losses in the fertility study. © 2000 Society of Chemical Industry     

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.     

Ultrastructure of o/w emulsions stabilized by faba bean protein isolates

An ultrastructural comparison is given for dispersions of a protein isolate (FBPI) from faba beans (Vicia faba L.) and its highly acetylated derivative (AFBPI) as well as for various o/w emulsions stabilized by FBPI and AFBPI. Both protein isolates contain substantial amounts of surface-active phospholipids (about 3%) which occur as vesicles (diameter 30 … 500 nm). Their membranes and rather cores contain protein. Interfacial protein layers of Triolein/Water-emulsion droplets possess smooth external surfaces and rather coarse internal surfaces with peculiar paracrystalline structured areas. Tangible differences are found in the droplet-size distribution and ultrastructure of sunflower-oil/water emulsions due to both the homogenization process (high pressure homogenizer or ultrasonic disintegrator) and the acetylation of the isolate. The modification by acetylation increases the emulsifying activity of the isolate and prevents the strong aggregation of oil droplets observed in FBPI-stabilized emulsions.     

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.     

Low methoxy pectin/protein interaction in o/w emulsions - Effects of acetylated faba bean globulin

The addition of low methoxy pectin to maximal acetylated faba bean globulin in o/w emulsion leads in the pH range between 5.5 and 6.5 to an increased protein content in the protein film around the oil droplets. This effect is accompanied with a rise of the apparent viscosity and flow behaviour index of the emulsions. In agreement with these modifications increased emulsion stability against creaming is found.     

Some viscosity characteristics of faba bean protein isolates within a pH range relevant for foods

The rheological behaviour of concentrated aqueous dispersions of unmodified (FBPI I) and acetylated (FBPI I) faba bean (Vicia faba L. minor) protein isolates are investigated within a pH range of 4.0 up to 7.5. Besides the fact that equal concentrated dispersions of FBPI I show a much lower apparent viscosity η than those prepared with FBPI II, η and the flow behaviour index n depend also on the kind of preparation. Especially the direction of pH shifting and the mode of pH adjustment lead to marked differences of the rheological properties. In the case of FBPI II dispersions a maximum of η and n is shown at pH 5.5 to 6.5, seldom at pH 7.0, probably connected with a maximum of the hydrodynamic volume. Holding the aqueous dispersions for 24h causes mostly an increase of η and n.     

Functional and electrophoretic characteristics of faba bean (Vicia faba) flour proteins as affected by germination

Faba beans (Vicia faba) were germinated at room temperature for 3 and 6 days respectively. The effect of germination on the protein fractions, protein solubility index, PAGE pattern and some functional properties i.e. emulsification capacity (EC), foaming capacity (FC), foam stability (FS), water and fat absorption capacities of the flour was studied. Germination decreased albumins, globulins and prolamins at different levels but non protein nitrogen and glutelins were increased. The protein solubility index was high at both extreme pH values with an isoelectric point (IP) at pH of 4.4-4.5. The solubility of the protein slightly increased due to germination at all the pH values. PAGE pattern revealed on obvious dissociation and utilization for both fast and slow moving protein fractions during germination. Emulsification and foaming properties vs pH profile were similar to the pattern of solubility vs pH. Both properties were high at acidic and alkaline pH's and the minimum values were at pH 4 to 5. Germination process improved EC, FC and FS of the flour in comparison with that of dry bean flour. Water absorption of faba bean flours was improved during germination but the fat absorption markedly decreased.     

Properties of spray-dried and freeze-dried faba bean protein concentrates

Summary  A protein concentrate from faba bean seeds was prepared by isoelectric precipitation and spray-dried. Its functional properties were measured and the results obtained were compared to those from another concentrate prepared by the classical freeze-drying technique. The functional properties were found to be indistinguishable. However, the protein solubility profile was different depending on the preparation technique. Some antinutritional factors (trypsin inhibitors, tannins and phytates) were also analysed. Both protein concentrates showed lower concentrations of tannins and phytates than the seeds.     

Influence of acetylated faba bean protein isolate on the rheological behaviour of O/W emulsions (Short communication)

Acetylated faba bean protein isolate (AFBPI) is particularly suitable for the stabilisation of O/W emulsions in acid and neutral pH regions. An essential feature of the consistency of O/W emulsions stabilised with AFBPI is an attractive creamy texture and non-slimy mouthfeel [7]. The aim of the present paper was to investigate the influence of AFBPI with different degrees of acetylation on the rheological behaviour of neutral and acidified, freshly prepared, concentrated oil-in-water emulsions.     

Chemical characteristics and physico-chemical properties of faba bean starch isolated from the by-product after protein extraction

Studies were made on the effect of protein extraction from faba bean flour, using water, whey and waste effluents from potato processing on chemical composition of starch and its physico-chemical properties. The results showed that the chemical composition of starch obtained from the by-product was different compared to native starch. The range of gelatinization temperature and maximal viscosity at 95 °C were also noticeably changed compared to native starch.     

Contribution to the characterization of acetylated protein fractions of vicia faba in view of their functional properties

Whilst the emulsifying properties of the protein fraction of vicia faba are almost independent on the acetylation degree, the shear modulus of the gels produced by heat denaturation increases at first with increasing acetylation degree, decreases with further increase of the acetylation, and comes finally to zero for very high acetylation degrees. By changes of pH and by influence of added NaCl, CaCl₂, AlCl₃, and starch, the shear modulus of gels of acetylated protein fractions of vicia faba can be increased, by addition of sunflower oil it can be decreased. On the base of studies on the fraction profile and on the changes of the content of sulfhydryl and disulfide groups of the protein fractions of vicia faba and the corresponding gels in dependence on the acetylation degree, an interpretation of the results is given.     

A method for the characterization of breakdown/reforming behaviour of faba bean protein dispersions

The present paper is concerned with the Doherty/Hurd method [1] for the investigation of the influence of NaCl, CaCl₂ and pectin on the structural breakdown/reforming behaviour of dispersions containing acetylated faba bean protein isolate (AFBPI).     

Off-flavour reduction in Vicia faba bean protein isolate

Acid gels incorporating protein isolates from Vicia faba beans have an off-flavour. The odour intensity of this characteristic was quantified on a category scale, and the effect on off-flavour of different methods of protein isolation or addition of flavours to the gels was quantified.Analysis of variance (during the protein isolate production) shows that the defatting or isoelectric washing of the bean flour, or the addition of a strawberry aroma concentrate to the gel itself, caused a significant reduction in the off-flavour of the acid bean protein gel. A combination of defatting and isoelectric washing of the bean flour lead to the greatest reduction in off-flavour.     

The relationships between physicochemical properties and conformational features of succinylated and acetylated kidney bean (Phaseolus vulgaris L.) protein isolates

The effects of succinylation and acetylation on some physicochemical properties and conformational features of kidney bean protein isolate (KPI) were investigated. The extent of N-acylation progressively increased up to 93–94% with increasing anhydride-to-protein ratio (0–1.0 g g^?1), while the O-acylation occurred only after extensive blocks of ε-amino groups. Zeta potential and size exclusion chromatography analyses indicated that the acylation and the succinylation in particular led to decreases in isoelectric point and zeta potential at neutral pH, in an extent of acylation dependent manner, while the association/dissociation state of the vicilin was slightly affected by the acylation. The surface hydrophobicity was also remarkably affected by the acylation, but the influence varied with the type and extent of acylation. Differential scanning calorimetry (DSC), intrinsic fluorescence and near-UV and/or far-UV CD spectroscopic analyses showed significant changes in tertiary and/or secondary conformations of the proteins in KPI, with extent of acylation, especially extent of succinylation. These phenomena suggest close relationships between the physicochemical properties and tertiary and/or secondary conformational features of the proteins in acylated KPI samples. It is also suggested that the physicochemical and conformational properties of KPI could be modulated by selecting the type and level of the applied anhydrides.     

The effect of coagulum washing on the quality of soybean and faba bean isolates

Protein isolates of faba bean and soybean, obtained using waste effluents of potato as protein extrahent, and water or 86% ethanol or 2% ascorbic acid for washing coagulum, were investigated. Both the use of 86% ethanol and 2% ascorbic acid lowered the solubility of isolates (approx. 1.7–11.9%), stronger protein denaturation being caused by ethanol. Although the use of waste effluents of potato increased trypsin inhibitors activity compared with the use of water, applying ethanol or ascorbic acid washing considerably lowered this activity. The use of 86% ethanol also caused an elimination of approx. 60% phytates from soybean isolates and a little less from faba bean ones. Ascorbic acid eliminated these undesirable compounds only to a small extent. In the case of 86% ethanol the organoleptic properties of isolates were found to have been improved. The isolates were of lighter colour and they were completely devoid of the leguminous taste.     

Effect of nutritional status of faba bean (Vicia faba L.) on protein solubility profiles

A field experiment was carried out to study the effect of mycorrhizal inoculation. phosphorus and sulphur fertilization, under two water regimes, on protein solubility fractions of faba bean. The major protein fraction of faba bean was the globulin fraction that ranged from 69.5 to 78.1%. Phosphorus treatment significantly (P⩽0.05) increased the globulin fraction of faba bean seeds in the wet treatment but significantly (P⩽0.05) decreased it in the dry treatment. All fertiliser treatments significantly (P⩽0.05) increased the albumin fraction in the wet treatment, whereas only treatments of mycorrhiza, mycorrhiza+sulphur and mycorrhiza+phosphorus+sulphur significantly increased it in the dry treatment compared to control. With the exception of the treatment mycorrhiza+sulphur, all other fertilisation treatments showed prolamin contents of faba bean seeds, similar to that of the control in the wet treatment. The G₃-glutelin fraction of faba bean ranged from 8.9 to 14.4%. Treatments with sulphur, mycorrhiza and mycorrhiza+sulphur significantly increased the G₃-glutelin fraction, whereas phosphorus and mycorrhiza+phosphorus treatments significantly decreased it. The insoluble protein (residue) of faba bean ranged from 1.8 to 3.4%. Generally, fertiliser treatments significantly increased the insoluble protein in the wet treatment. With the exception of treatments mycorrhiza and mycorrhiza+sulphur, all other fertiliser treatments significantly increased the insoluble protein content in the dry treatment. Water regime significantly (P⩽0.05) affected the protein fractions.     

绿豆分离蛋白的葡聚糖糖基化改性研究

为改善绿豆分离蛋白（MBPI）的理化特性,利用葡聚糖（Dextran）接枝改性MBPI,并对改性后蛋白的溶解性、乳化特性、表面疏水性、亚基结构的变化进行研究。SDS-PAGE凝胶电泳分析结果表明,MBPI和Dextran接枝反应后生成了分子量较大的共价复合物,表面疏水性分析表明,相比于未处理蛋白,MBPI-Dextran共价复合物的表面疏水性含量降低,溶解性和乳化特性的研究表明,改性后的蛋白质溶解性和乳化特性得到不同程度的改善。      

绿豆分离蛋白功能特性研究

研究了绿豆分离蛋白的功能特性,探讨了pH值、温度、离子强度、蛋白质质量分数诸因素对绿豆分离蛋白溶解性、吸水性与吸油性、起泡性与起泡稳定性、乳化性与乳化稳定性、黏度的影响.结果表明,在pH=8的溶液中,绿豆分离蛋白的乳化性最好(45.2);在c(NaCl)=0.6 mol/L的溶液中,绿豆分离蛋白表现出较好的起泡性(160%);当w(绿豆分离蛋白)=9%时,起泡性和起泡稳定性最佳(分别为270%,77.8%～100%);当w(绿豆分离蛋白)=10%时,绿豆分离蛋白溶液的黏度可达7050 mPa·s.