Sándor Tömösközi

Isolation and study of the functional properties of pea proteins.

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying--and foaming properties, water--and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.

Expression of a synthetic neutralizing epitope of porcine epidemic diarrhea virus fused with synthetic B subunit of Escherichia coli heat labile enterotoxin in rice endosperm.

Epitopes often require co-delivery with adjuvant and targeting proteins to enable recognition by the immune system, and this approach may also increase the efficacy of the antigen. In this study, we assess and describe the ability of transgenic rice plants to express a fusion protein consisting of the B-subunit of the Escherichia coli heat-labile enterotoxin (LTB) and a synthetic core-neutralizing epitope (COE) of porcine epidemic diarrhea virus (PEDV), inducing an enteric disease that is seen most predominantly in piglets. Both components of the fusion proteins were detected with Western blot analysis. The fusion protein was determined to assemble into pentamers, as was evidenced by its ability to bind to GM1 gangliosides, and evidenced an average level of expression in a trangenic rice endosperm. This indicates that the expression system of the plant is capable of generating a sizable amount of antigen, possibly allowing for the successful development of an edible vaccine.

Expression of cholera toxin B subunit in transgenic rice endosperm.

The synthetic cholera toxin B subunit (CTB) gene, modified according to the optimized codon usage of plant genes, was introduced into a plant expression vector and expressed under the control of the Bx17 HMW (high molecular weight) wheat endosperm-specific promoter containing an intron of the rice act1. The recombinant vector was transformed into rice plants using a biolistic-mediated transformation method. Stable integration of the synthetic CTB gene into the chromosomal DNA was confirmed by PCR amplification analysis. A high level of CTB (2.1% of total soluble protein) was expressed in the endosperm tissue of the transgenic rice plants. The synthetic CTB produced only in the rice endosperm demonstrated strong affinity for GM1-ganglioside, thereby suggesting that the CTB subunits formed an active pentamer. The successful expression of CTB genes in transgenic plants makes it a powerful tool for the development of a plant-derived edible vaccine.

Sponge and dough bread making: genetic and phenotypic relationships with wheat quality traits

The genetic and phenotypic relationships among wheat quality predictors and sponge and dough bread making were evaluated in a population derived from a cross between an Australian cultivar ‘Chara’ and a Canadian cultivar ‘Glenlea’. The genetic correlation across sites for sponge and dough loaf volume was high; however, phenotypic correlations across sites for loaf volume were relatively low compared with rheological tests. The large difference between sites was most likely due to temperature differences during grain development reflected in a decrease in the percentage of unextractable polymeric protein and mixing time. Predictive tests (mixograph, extensograph, protein content and composition, micro-zeleny and flour viscosity) showed inconsistent and generally poor correlations with end-product performance (baking volume and slice area) at both sites, with no single parameter being effective as a predictor of end-product performance. The difference in the relationships between genetic and phenotypic correlations highlights the requirement to develop alternative methods of selection for breeders and bakers in order to maximise both genetic gain and predictive assessment of grain quality.

Comparative study of commercially available gluten ELISA kits using an incurred reference material

Handling major hypersensitivity reactions (e.g. celiac disease) triggered by proteins of wheat and other cereals is a challenging task for healthcare systems, legislative forces and the related fields of food analysis as well. In spite of the fact that there are available official threshold levels for labelling the absence of gluten, which is considered to be the toxic protein fraction of wheat, barley and rye, validation of the analytical methodology supporting regulatory requirements is currently problematic. The main limiting factors of method validation are the lack of reference methods and reference materials. The objective of this study was to provide a solution to this problem. An incurred reference material in a model food matrix was developed and studied by commercially available ELISA test kits as a part of the activity of the Food Allergen Working Group within the FP6 funded EU project MoniQA. After successful completion of the reference material development process, the incurred material was u...

Isolation, functional properties and potential use of protein preparations from lupin

Protein isolates were prepared by extraction with diluted NaOH (resulting the highest yield) and precipitation with HCl from lupin seeds grown in Egypt and Hungary. Protein content, amino acid composition, biological value and functional properties of isolates were studied. The proteins were high in lysine but relatively low in sulfur-containing amino acids. Good solubility and moderate emulsifying, foaming and gel-forming properties of isolates were observed. Enrichment of fruit- and vegetable-based baby foods with these isolates resulted in products with excellent organoleptic properties and moderate biological value. Additional enrichment with small quantities of methionine increased significantly the biological value without any negative changes of organoleptic characteristics.

Comparison of the effects of different heat treatment processes on rheological properties of cake and bread wheat flours.

Dry and hydrothermal heat treatments are efficient for modifying the technological-functional and shelf-life properties of wheat milling products. Dry heat treatment process is commonly used to enhance the volume of cakes. Hydrothermal heat treatment makes wheat flours suitable as thickener agents. In this study, cake and bread wheat flours that differed in baking properties were exposed to dry (100 °C, 12 min) and hydrothermal (95 °C, 5 min, 5-20 l/h water) heat treatments. Rheological differences caused by the treatments were investigated in a diluted slurry and in a dough matrix. Dry heat treatment resulted in enhanced dough stability. This effect was significantly higher in the cake flour than the bread flour. Altered viscosity properties of the bread flour in the slurry matrix were also observed. The characteristics of hydrothermally treated samples showed matrix dependency: their viscosity increases in the slurry and decreases in the dough matrix. These results can support us to produce flour products with specific techno-functional properties.

Comparison of Different Types of NIR Instruments in Ability to Measure β-Glucan Content in Naked Barley

ABSTRACT Importance of β-glucan in human nutrition is mirrored in numerous approval applications registering β-glucan containing products as health beneficial products in accordance with forthcoming EU Health Claims Regulation. In comparison to other cereals, barley contains considerable amounts of β-glucan. Naked barley is of particular interest because it circumvents the costs and loss of beneficial substances related to dehusking. In this study, the potential of near-infrared spectroscopy as an accurate, fast and economic method of determination of β-glucan in naked barley was appraised. Four different near-infrared instruments were used to analyze 107 barley samples, in both whole grain and milled form. Importantly, both black and purple pericarp samples, which are of additional nutritional interest due to high anthocyanin content, and waxy samples, which show an extraordinary high β-glucan content could be analyzed within the same calibration set as the normal samples. All tested dispersive near-infr...

Expression of the 1D×5 High Molecular Weight Glutenin Subunit Protein in Transgenic Rice

We generated and analysed transgenic rice lines synthesizing substantial amounts of high-molecular-weight glutenin subunit (HMW-GS) from wheat. Particle bombardment has been used to transform rice cultivars (Orysa sativa L.) with a cassette carrying the gene of 1D×5 HMW glutenin subunit. Twelve independent lines were recovered and PCR results on genomic DNS confirmed the integration of the transgene into it. Five lines set seeds. Seeds were analysed by SDS-PAGE and Western blot and we proved the presence of foreign protein in the starchy endosperm. The amount of 1D×5 HMW-GS in rice endosperm represents 0.75–3.18% of the alcohol soluble proteins. These results are the first example of significantly changing storage protein composition of rice exploiting the method of gene technology. This alteration may have considerable effect on the functional properties, including strength and stability of the dough made of transgenic rice flour.

Comparative Study of the Effect of Incorporated Individual Wheat Storage Proteins on Mixing Properties of Rice and Wheat Doughs

The aim of this work was to compare the effects of incorporated wheat storage proteins on the functional properties of rice and wheat flours. The advantage of rice as a base flour compared to wheat is that it does not contain any wheat flour components and, therefore, has no interactive effect between wheat glutenin proteins. The incorporation of individual HMW glutenin subunit proteins (Bx6, Bx7, and By8) in different ratios had significant positive effects on the mixing requirements of both rice and wheat doughs. Reconstitution experiments using two x+y type HMW-GS pairs together with a bacterially expressed LMW-GS have been also carried out in this study. The largest effects of polymer formation and mixing properties of rice flour dough were observed when Bx and By subunits were used in a 1:1 ratio and HMW and LMW glutenin subunits in a 1:3 ratio. However, using the same subunit ratios in wheat as the base flour, these synergistic effects were not observed.