Search

As part of our studies on the mechanisms of bread staling, starch bread was used as a research tool that enables us to gain insights into the individual contributions that starch and gluten have on staling. Reconstitution experiments have demonstrated that bread of equivalent specific loaf volume stales at the same rate irrespective of protein concentration, or type of protein. However, other properties of bread, such as specific loaf volume, may be altered by specifically changing the protein component in the flour.

Correspondance: micard@supagro.inra.fr; International audience; Pasta is popular for its ease of cooking and its low glycaemic index (GI). This interesting nutritional property can be attributed to its specific compact structure generally described as a protein network entrapping starch granules. Despite this low GI, pasta is poor in fibres and lack some essential amino acids. To enhance its nutritional composition, pasta can be fortified with non-traditional ingredients such as legume flours. The objective of this study was to investigate the impact of legume flour addition on pasta structure and the inherent consequences on the in vitro digestibility of starch. The addition of a high level (35%, w/w) of legume flour, especially split pea flour, induced some minor structural changes in pasta. The inclusion of fibres, the dilution of gluten proteins by albumins and globulins, and the larger amount of thin protein films (in split pea pasta) may have favoured higher susceptibility of starch to digestive enzymes. At the opposite, the presence of some partially gelatinised starch granules in the core of fortified pasta may have favoured the decrease in the in vitro starch digestibility. As a consequence, a high level of legume flour addition in pasta did not have any significant impact on its in vitro starch digestibility. A high level of split pea and faba bean flours can thus be added to pasta to increase its nutritional composition while keeping its low glycaemic index

Celiac disease (CD) is a permanent intolerance to wheat prolamins and related proteins displayed by genetically susceptible individuals. Blocking or modulation of CD-specific T cell response by altered prolamin peptides are currently considered as a potential alternative to the only effective therapy of CD based on a life-long gluten-free diet. Two prolamin peptides, the 9-mer ASRVAPGQQ and the 10-mer GTVGVAPGQQ sequences, were identified by mass spectrometry in the peptic/tryptic digest of prolamins (PTP) from durum wheat (Triticum turgidum ssp. durum) cv. Adamello, and investigated for their ability to preclude the stimulation of CD-specific mucosal T cells by gluten proteins.Gluten-specific polyclonal intestinal T cell lines from five CD children (mean age 5 years) were exposed to 50 microg/ml of a deamidated PTP from whole flour of common wheat (T. aestivum) cv. San Pastore, and tested for proliferation and production of interferon-gamma (INF-gamma) and interleukin 10 (IL-10). The same experiment was performed in the presence of 20 microg/ml of the 9-mer or the 10-mer peptide.T cells exposed to PTP showed a threefold increase in proliferation and INF-gamma production, and a significant (Por= 0.05) reduction in IL-10 secretion as compared with control cells incubated with the culture medium. Addition of either the 9-mer or the 10-mer peptide to PTP downregulated T cell proliferation and INF-gamma production, and caused a significant (Por= 0.05) increase in IL-10 secretion.The T cell reactivity elicited by PTP is precluded by both the 9-mer and the 10-mer sequence, suggesting that over-expression of these proteolytically stable peptides may result in a wheat flour with reduced toxicity for CD patients.

Gradient SDS-PAGE analysis of some Canadian wheat cultivars and breeders' lines revealed that there was variation in the mobility of the high molecular weight (HMW) glutenin subunit 7. One group of cultivars/lines had a subunit 7 band that was comparable to that found in the cultivar Chinese Spring, whereas another group had a slightly more mobile band comparable with the subunit 7 band in Bezostaya. This latter band was designated as HMW glutenin subunit 7* in order to differentiate it from the subunit 7 component present in cultivars such as Chinese Spring. Reversed-phase high-performance liquid chromatographic (RP-HPLC) analysis showed that subunits 7 and 7* had comparable elution times. Quantitatively, the proportion of subunit 7 relative to the total amount of HMW glutenin subunits was significantly higher (41·2± 1·5 %) than subunit 7* (27·1 ±0·9 %). The relative proportions were consistent within each group of cultivars as indicated by low coefficients of variation, 3·6 and 3·4 %, respectively. Similarly, the absolute peak area, on a per cent protein basis, was significantly higher for subunit 7 than for subunit 7*. Subunit 7* was found in combination with subunit 9 or subunit 8 or a variant of subunit 8 (as determined by RP-HPLC) designated subunit 8*. This indicated that there are at least three alleles controlling this subunit. Subunit 7 was present in combination with subunits 8 or 8*, and thus there are at least two alleles controlling this subunit. Subunit 7 may be associated with greater dough strength and decreased extractability of gluten proteins. The identification, therefore, of these subunits could be useful for selection purposes in a wheat breeding program.

Capillary electrophoresis was used to characterize glutenin proteins from ancient varieties of Southern Italy common wheat and to determine the technological properties of wheat flours based on a glutenin index. Three zones were identified in the electropherograms, indicated as A, B, and C according to electroelution order. The three zones corresponded to the low molecular weight glutenin subunits and to the y- and x-type high molecular weight subunits, respectively. The ratio B/C was correlated to the alveographic parameter P/L. These results indicated that flours resulting in a B/C ratio lower than 2 produced elastic doughs whereas flours resulting in a B/C ratio higher than 2 produced doughs more resistant to extension. This study showed that capillary electrophoresis is useful for determining the types and quantities of gluten proteins in the evaluation of wheat-flour technological properties of a limited number of noncommercial varieties as evidenced by the x-type content which seems to strongly influence the flour technological parameters.

To improve compliance with a gluten-free diet in coeliac disease a simple prototype test kit was developed to detect gluten in foods for use at home. The test is based on monoclonal antibodies to heat-stable gluten proteins which crossreact appropriately with barley and rye proteins. It is suitable for use with a wide range of raw or cooked foods. The food is extracted with dilute hydrochloric acid and 1 drop of the extract transferred to an antibody-coated tube; enzyme-labelled gluten detection antibody is added and after 3 min the tube is washed and colour developer is added. The reaction is stopped after 2 min, stabilising the blue colour. The home kit was compared with a quantitative laboratory kit, and the qualitative agreement was very good. The kit could distinguish foods with trace gluten contents (acceptable for a "gluten-free" diet) from those with a slightly higher but unacceptable gluten content. In a trial of the prototype kit by 47 coeliac disease patients of diverse ages and educational backgrounds, 93% of tests correctly identified foods as acceptable or unacceptable.

Recent proteomic studies of the wheat grain have focused on the endosperm tissuedue to its importance to productivity and quality [1-3]. The gluten proteins are ofmajor interest in these studies, since they determine the characteristics of extensibility,elasticity, and gas-holding capacity that are unique to wheat flour doughs. The glutenProteins encompass-more than 80% of theendosperm protein and consist of gliadinsand glutenin subunits. The gliadins are a polymorphic collection of monomeric pro-teins soluble in 70% alcohol that are separated into a, y, and

The improvement of dough functionality through different enzymes is a new strategy used in the last years for the bakery industry. Some enzymes as glucose oxidase (GOX, EC 1.1.3.4) and transglutaminase (TG, EC 2.3.2.13) modify the protein fraction, mainly the gluten proteins, but is not well-known the influence of these enzymes on the structure of the dough components [1, 2].

We studied N uptake and distribution in wheat, and the incorporation of nitrogen and carbon into gluten and non-gluten proteins using a double-labelling approach with 15N and 13C. Doses of N-fertilizer were split and applied at emergence, onset of stem elongation, and heading at rates of 280/140/140 mg N pot(-1), respectively simulating 90/45/45 kg N ha(-1). Five different combinations of N-fertilizations containing no or 10 % 15N were performed. The recovery of 15N added at the stages emergence, stem elongation or heading were 42, 60, and 64 %. Application of 15N at all three stages yielded in 51 % recovery. Remobilisation of straw N was greater for Golia. The 15N concentration in gluten proteins of Golia show higher values than Gonen. The ratio of 15N gluten/15N non-gluten proteins of Golia were higher, which implies a lower non-gluten protein activity during grain filling. The 13C concentration in gluten and non-gluten proteins did not differ between both cultivars.

Celiac patients are at risk to develop an autoimmune liver disease. The aim of this study was to describe the clinical features of children and adolescents presenting with an autoimmune liver disease associated with celiac disease.A retrospective multicenter national survey was made for the period 1990-2005.Among 140 pediatric patients with autoimmune liver disease in italy, we identified 23 with celiac disease: 19 with autoimmune hepatitis, 2 with autoimmune cholangitis, and 2 with overlap syndrome. Diagnosis of celiac disease preceded the diagnosis of liver disease in 18 of them, but elevation of aminotransferase activity was present in 16 when celiac disease was diagnosed. Acute hepatitis developed in 2 infants on gluten-free diet, and a hidden celiac disease was discovered in 5 other patients. Nineteen patients had liver-related non-organ-specific autoantibodies. Liver histology showed inflammatory lesions with features of autoimmune damage and different degrees of fibrosis in all of them and cirrhosis in 4. All patients, on gluten-free diet, achieved remission on immunosuppressive therapy, 14 relapsed because of discontinuation of therapy or during spontaneous gluten challenge, 20 are still on immunosuppressive treatment, and 3 could stop therapy.Autoimmune liver diseases are frequently associated with celiac disease, but they might remain undiagnosed because of lack of symptoms, because of absence of liver-specific autoantibodies, or because of a misdiagnosis of celiac hepatitis. Acute hepatitis in celiac patients should induce one to suspect an autoimmune origin. Patients with autoimmune liver disease might have a hidden celiac disease, suggesting a rigorous check in any cryptogenic liver disease.

To analyze gluten proteins involved in celiac disease (CD) by proteomic analysis, prolamins extracted from hexaploid wheat varieties were analyzed by SDS-PAGE and 2-DE. Differences between staining methods (CBB, silver nitrate, SYPRO Ruby, and CyDye) were analyzed in comparison to immunoblotting. Staining efficiency varied per protein across methods, and complete staining of all gluten proteins could not be achieved by one of these methods. Care should be taken in the selection of staining method especially if one wants to relate the results to data obtained by immunoblotting.

Coeliac disease (CD) is a food-related problem. Increasing knowledge about the diversity in CD toxicity of individual wheat species and varieties, and of the individual gluten proteins enables the

Publisher Summary Since the recognition that wheat gluten exacerbates celiac disease, comparatively slow progress has been made in developing methods for the quantitative determination of celiac disease-toxic proteins. The first Codex Standard for Gluten-Free Foods was established in 1981, which was limited to the analysis of wheat starch by means of nitrogen determination. A revision of this standard is still under way. The general major problem is that the analyte (gluten proteins) is incompletely defined with respect to protein composition and toxicity, and an aggravating factor is that gluten proteins are often subjected to denaturation or proteolysis during food processing. Moreover, the choice of an appropriate reference protein is pivotal in getting accurate results. Numerous analytical methods based on immunochemistry, PCR, MS, or HPLC have been developed, but only a couple have met the minimum requirements of sensitivity, selectivity, precision, speed, and availability. The Draft Revised Codex Standard gives only a general outline of a method and recommends an immunochemical approach. Though the recent Revised Draft Codex Standard and the proposed method are not perfect, they represent an important progress compared to Codex Stan 118–1981. ELISA remains the first choice for gluten analysis, but alternative methods will be necessary to control ELISA results.

Factor analysis and multivariate chemometric modelling for rapid assessment of baking quality of wheat cultivars from Slavonia region, Croatia, have been applied. The cultivars Žitarka, Kata, Monika, Ana, Demetra, Divana and Sana were grown under controlled conditions at the experimental field of Agricultural Institute Osijek during three years (2000–2002). Their quality properties were evaluated by 45 different chemical, physical and biochemical variables. The measured variables were grouped as: indirect quality parameters (6), farinographic parameters (7), extensographic parameters (5), baking test parameters (2) and reversed phase-high performance liquid chromatography (RP-HPLC) of gluten proteins (25). The aim of this study is to establish minimal number (three), i.e. principal factors, among the 45 variables and to derive multivariate linear regression models for their use in simple and fast prediction of wheat properties. Selection of the principal factors based on the principal component analysis (PCA) has been applied. The first three main factors of the analysis include: total glutenins (TGT), total ω-gliadins (Tω-) and the ratio of dough resistance/extensibility (R/Ext). These factors account for 76.45 % of the total variance. Linear regression models gave average regression coefficients (R) evaluated for the parameter groups: indirect quality R=0.91, baking test R=0.63, farinographic R=0.78, extensographic R=0.95 and RP-HPLC of gluten data R=0.90. Errors in the model predictions were evaluated by the 95 % significance intervals of the calibration lines. Practical applications of the models for rapid quality assessment and laboratory experiment planning were emphasized., U radu je primijenjena kemometrijska analiza za brzu i jednostavnu ocjenu pekarske kakvoće kultivara pšenice uzgojenih u Slavoniji (Hrvatska). Analizirani su kultivari Žitarka, Kata, Monika, Ana, Demetra, Divana i Sana iz kontroliranog uzgoja tijekom 2000-2002. godine. Kakvoća je pšenice analizirana mjerenjem 45 kemijskih, fizikalnih i biokemijskih parametara. Mjereni su parametri svrstani u ove skupine: indirektni parametri kakvoće, farinografski i ekstenzografski, parametri pokusnog pečenja kruha, te RP-HPLC parametri glutena. Svrha je istraživanja bila određivanje minimalnog broja varijabli (tri vodeća faktora), između 45 mjerenih veličina, na osnovi kojih se multivarijantnim modelom mogu jednostavno i brzo procijeniti sva analizirana svojstva pšenice. Primijenjena je kemometrijska analiza glavnih komponenata (PCA) za određivanje vodećih faktora. Analizom su određena tri vodeća faktora: ukupni glutenini TGT, ukupni ω-glijadini (Tω-), te omjer između otpora i rastezljivosti tijesta (R/Ext), kojima je objašnjeno 76,45 % od ukupne varijance svih eksperimentalnih podataka. Linearni regresijski modeli imaju ove prosječne vrijednosti koeficijenata korelacije za pojedine skupine: indirekti parametri kakvoće R=0,91; farinografski R=0,78; ekstenzografski R=0,95; parametri pokusnog pečenja kruha R=0,63, te RP-HPLC parametri glutena R=0,90. Istaknuta je važnost primjene modela za brzu procjenu kakvoće pšenice, a i za planiranje eksperimentalnog rada.

The technological properties of wheat flour are strongly dependent on total glutenin proteins composition and quantity. The aim of this study was to estimate gluten strength of 6 commercial winter wheat cultivars grown in eastern Croatia in relation to HMW-GS composition and quantity, as well as quantity of total glutenins. For gluten strength evaluation gluten index method and physical dough properties determination have been applied. Considering HMW-GS composition, the most frequent subunits at Glu- A1 locus were N, at Glu-B1 locus 7+9 and at Glu-D1 locus 2+12. The analyzed cultivars Žitarka, Golubica and Janica in spite of HMW-GS 2+12 domination have shown good technological properties, regarding the obtained indirect quality parameters and dough rheological properties. Cultivars Srpanjka, Soissons and advance line Osk 266/03 according to obtained quality parameters have been characterized as bread improvers. These cultivars had the highest contents of total glutenins, as well as HMW-GS.

The dough handling properties of a number of Sr31 and non-Sr31 wheats were examined in the laboratory test bake procedure using a National test bake mixer. Dough stickiness was not apparent in any of the wheats at optimum dough development. The baking quality at optimum dough development of Sr31 wheats was comparable to non-Sr31 wheats. However, after optimum dough development Sr31 wheats broke down and exhibited dough stickiness more rapidly with continued mixing than non-Sr31 wheats. A new dough parameter is introduced, dough un-mixing time, and is defined as the time from the point of optimum dough development to the point where the dough breaks down as a result of continued mixing to produce a sticky, non-cohesive mass. It is shown that Sr31 wheats have shorter dough un-mixing times than non-Sr31 wheats, and that dough un-mixing times for both Sr31 and non-Sr31 wheats are influenced by environmental factors, particularly those which determine grain protein content. A selection strategy for breeding Sr31 wheats with commercially acceptable dough properties is indicated by placing Sr31 in a genetic back-ground of high quality gluten proteins, and selecting for long dough un-mixing times.

A sensitive competition enzyme‐immunoassay for quantification of gluten in foods was developed, using horseradish peroxidase‐labelled monoclonal antibodies. Selected antibodies specific for wheat omega‐gliadin components were used, and these antibodies bound proteins from the related cereals, rye and barley, which are also toxic to individuals with gluten‐intolerance (coeliac disease). Binding of these antibodies was not inhibited by heating of gluten during cooking or baking and the assay did not detect cereals not toxic in coeliac disease, such as maize or rice. Gluten could be quantified at higher levels in meat products or in cereal products such as flours or baked goods. Results were not affected by wheat variety. Quantitiative results could be obtained using simple extraction techniques and solvents (40% or 70% ethanol). Detection of gluten was quantitative in a wide range of foods, except for certain products containing gluten proteins that had been subjected to severe heat, enzymic or chemical tre...

Surface forces and interactions are a key issue in colloid and surface science, including biopolymer systems. Covalent and ionic bonds determine the structure and composition of materials, but the weaker non-covalent interactions define their functions. This thesis deals with the surface forces and interactions occurring between biopolymer surfaces and affecting the self-assembly and interfacial behaviour of biopolymers. The research was aimed at deepening the understanding of molecular interactions and the nature and strength of surface forces in the studied biopolymer systems. The main research tool was atomic force microscopy (AFM). This technique allows imaging of the sample topography in either gas or liquid environments at high resolution. Data on intra- and intermolecular interactions can also be obtained. Interesting phenomena revealed by AFM were supported and confirmed by other relevant surface analytical techniques. The nanomechanical force measurements focused on interactions relevant in papermaking, i.e. between cellulose and xylan, and food technology, i.e. between gliadins (wheat gluten proteins). In the cellulose-xylan interaction work the colloidal probe technique was exploited by attaching cellulose beads to the tip and to the sample surface. The interaction between these beads was measured in different xylan solutions. The main result of the cellulosic systems provided a new perspective on the role of xylan in papermaking. It has been reported previously that the adsorption of xylan increases paper strength and that this is due to formation of hydrogen bonds. Our results indicate that the increase in paper strength cannot originate from such bonds in wet paper, but must be due to effects of xylan on fibre bonds during drying of paper. The viscous and elastic properties of gliadins and glutenins facilitate the production of bread, pasta and many other food products from wheat flour. Gliadin proteins (alfa- and omega-gliadins) were attached to both thetip and the sample surfaces, and the interaction forces between monomeric gliadins (alfa-alfa, omega-omega, and alfa-omega) were measured. On the basis of the nanomechanical force measurements, different roles of different types of gliadins were proposed: whereas omega-gliadins still have acompact structure and are responsible for the viscous flow, alfa-gliadins have already started to participate in forming the network in dough. This may provide a new viewpoint in understanding the interfacial properties of gliadins in relation to baking. The studies of interfacial behaviour of biopolymers focused on hydrophobins, which are very surface active proteins. Hydrophobins are amphiphilic proteins which self-assemble due to the interplay of various surface forces and interactions in solution and at interfaces. Films of Class II hydrophobins, HFBI and HFBII, at the air-water interface were transferred to solid supports and imaged by AFM. The interfacial films of hydrophobins were imaged at nanometer resolution. The results showed that both HFBI and HFBII form organised structures at the air-water interface. Moreover, the nanostructured films formed spontaneously. The HFBI films were imaged and the organised pattern was seen both on the hydrophobic and the hydrophilic side. The dimensions were similar to those of hydrophobin tetramers in solution obtained by small angle X-ray scattering. Protein engineering enabled assignment of a specific functionality to HFBI. The results confirmed the expected orientation of hydrophobins at the air-water interface, and indicated that the hydrophobin retained its capability to form organised films and the covalently attached molecule its functionality.

It is well known that gluten plays a major role in determining cooking quality in durum wheat pasta. This work is an attempt to systematically elucidate the role of gluten quantity and nature in determining cooking quality as a function of the drying cycle used in the manufacturing process. Gluten and starch were fractionated from two durum wheat cultivars possessing good and poor gluten quality. Either of them were then added back to the original base semolina to alter its protein content and to produce two semolina series with identical protein contents. Semolinas were processed into pasta and dried following three drying programs (low, medium, and high temperature). Cooking quality was determined with sensorial, chemical, and instrumental methods. The results indicate that optimum cooking time is governed by gluten quality. The positive effect on cooking quality of increasing gluten contents and of the application of HT drying is evident in weak gluten samples, but it is not significant in the...

Genes encoding D-genome related gliadins and glutenin subunits have been transferred to durum wheat through chromosome engineering. In particular, segments containing genes corresponding to the pairs of high-molecular-weight glutenin subunits (HMWGS) 5 + 10 or 2 + 12, normally present at the Glu-D1 locus in bread wheat, have been introgressed into chromosome 1A of different durum wheat cultivars, replacing the null allele present at the Glu-A1 locus. Using the same approach or the bread wheat cultivar Perzivan, carrying a translocation involving the short arm of chromosomes I A and ID, the two alleles present at Gli-D1/Glu-D3 loci in most bread wheat cultivars, encoding gliadin and low molecular weight glutenin subunits (LMW-GS), have also been introduced into durum wheat.

Surface forces and interactions are a key issue in colloid and surface science, including biopolymer systems. Covalent and ionic bonds determine the structure and composition of materials, but the weaker non-covalent interactions define their functions. This thesis deals with the surface forces and interactions occurring between biopolymer surfaces and affecting the self-assembly and interfacial behaviour of biopolymers. The research was aimed at deepening the understanding of molecular interactions and the nature and strength of surface forces in the studied biopolymer systems. The main research tool was atomic force microscopy (AFM). This technique allows imaging of the sample topography in either gas or liquid environments at high resolution. Data on intra- and intermolecular interactions can also be obtained. Interesting phenomena revealed by AFM were supported and confirmed by other relevant surface analytical techniques. The nanomechanical force measurements focused on interactions relevant in papermaking, i.e. between cellulose and xylan, and food technology, i.e. between gliadins (wheat gluten proteins). In the cellulose-xylan interaction work the colloidal probe technique was exploited by attaching cellulose beads to the tip and to the sample surface. The interaction between these beads was measured in different xylan solutions. The main result of the cellulosic systems provided a new perspective on the role of xylan in papermaking. It has been reported previously that the adsorption of xylan increases paper strength and that this is due to formation of hydrogen bonds. Our results indicate that the increase in paper strength cannot originate from such bonds in wet paper, but must be due to effects of xylan on fibre bonds during drying of paper. The viscous and elastic properties of gliadins and glutenins facilitate the production of bread, pasta and many other food products from wheat flour. Gliadin proteins (alfa- and omega-gliadins) were attached to both thetip and the sample surfaces, and the interaction forces between monomeric gliadins (alfa-alfa, omega-omega, and alfa-omega) were measured. On the basis of the nanomechanical force measurements, different roles of different types of gliadins were proposed: whereas omega-gliadins still have acompact structure and are responsible for the viscous flow, alfa-gliadins have already started to participate in forming the network in dough. This may provide a new viewpoint in understanding the interfacial properties of gliadins in relation to baking. The studies of interfacial behaviour of biopolymers focused on hydrophobins, which are very surface active proteins. Hydrophobins are amphiphilic proteins which self-assemble due to the interplay of various surface forces and interactions in solution and at interfaces. Films of Class II hydrophobins, HFBI and HFBII, at the air-water interface were transferred to solid supports and imaged by AFM. The interfacial films of hydrophobins were imaged at nanometer resolution. The results showed that both HFBI and HFBII form organised structures at the air-water interface. Moreover, the nanostructured films formed spontaneously. The HFBI films were imaged and the organised pattern was seen both on the hydrophobic and the hydrophilic side. The dimensions were similar to those of hydrophobin tetramers in solution obtained by small angle X-ray scattering. Protein engineering enabled assignment of a specific functionality to HFBI. The results confirmed the expected orientation of hydrophobins at the air-water interface, and indicated that the hydrophobin retained its capability to form organised films and the covalently attached molecule its functionality.

The effects of translocations 1AL/1RS, 1BL/1RS on baking quality of bread winter wheat varieties were investigated. It was established the genetic features of manifestation of grain quality parameters depending on interaction of genotypes with translocations 1AL/1RS, 1BL/1RS and environmental conditions. There were identified the variability of baking quality due to variation the ratio of gluten proteins in varieties with 1AL/1RS, 1BL/1RS at different levels of protein content in grain

The time course of compositional changes in the polysaccharide and protein fractions, and of changes in protein structural properties, was investigated in grains of two Italian durum wheat cultivars, Ofanto and Duilio, and the pattern of changes was found to be specific to each cultivar. The fructo-oligosaccharide content in ripening kernels was different between cultivars, as was the pattern of starch accumulation. Evaluation of gluten proteins by Western-blotting using broad-specificity anti-gliadin antibodies showed the sudden appearance of immunoreactive proteins during ripening. Protein surface hydrophobicity and thiol content and accessibility were evaluated in conditions apt at assessing changes in protein interaction and/or in aggregative patterns. Proteins in the two cultivars showed differences in their surface hydrophobicity and in their content of accessible thiols. The simultaneous evaluation of changes in the individual components indicates that use of immature grains for the production of functional foods will require accurate monitoring of the rapidly evolving biopolymer patterns, and careful choice of the cultivar.

The strength and nature of interactions between monomeric gliadin proteins involving α–α, ω–ω, and α–ω interactions in 0.01M acetic acid, and the effect of urea has been investigated. It was shown by means of nanomechanical force measurements that the stretching events in the separation curve after adhesive phenomena originated from proteins. These stretching events displayed different responses of the α- and ω-gliadins to urea. While 2M urea caused the more globular α-gliadins to unfold, the β-turn-rich ω-gliadins remained fairly stable even in 8M urea. This suggests different roles for gliadins in the formation of dough; while the ω-gliadins are still in a compact structure being responsible for the viscous flow, the α-gliadins have already started to participate in forming the network in dough.© 2006 Wiley Periodicals, Inc. Biopolymers 83: 658–667, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

The gluten proteins of 15 winter wheat cultivars grown in eastern Croatia were studied for their contribution to the bread-making quality. Composition of high-molecular-weight glutenin subunits (HMW-GS) was analyzed by SDS-PAGE, while the quantity of gluten proteins was determined by combined extraction/RP-HPLC procedure. The results of the linear correlation analysis carried out on the particular gluten proteins and technological properties showed that the amount of total gluten content highly correlates with protein content. Among gluten proteins, the glutenins showed higher correlation with protein content, with pronounced influence of HMW-GS, than gliadins. Wet gluten content was significantly correlated to total gliadin quantity. Gluten index as gluten quality parameter was positively influenced by total glutenins and low-molecular-weight glutenin subunits (LMW-GS), and negatively, by the ratios of gliadin to glutenin (Gli/Glu), whereas the amount of gliadins was not important. Dough development time was strongly correlated with total gluten content, total glutenins and the Gli/Glu ratio. Dough mixing resistance was strongly affected by total glutenin content with pronounced influence of HMW-GS. Degree of dough softening is mainly negative influenced by total glutenins and ratio of Gli/Glu. Farinograph quality number as flour quality index was highly positively correlated with total glutenins, with emphasized influence of HMW-GS. The Gli/Glu ratio had the highest influence on dough maximum resistance. Dough extensibility showed moderate correlation with total gliadins. The results of the linear correlation indicated that loaves volumes were significantly influenced by total gluten proteins, HMW-GS and LMW-GS.

The gluten quality is essentially determined by HMW GS compositions and quantity of different gluten proteins. The aim of this study was to estimate protein quality of 15 winter wheat cultivars grown in eastern Croatia. Therefore, HMW GS composition was analysed by SDS-PAGE, while the quantitative determination of gliadins and glutenin subunits was obtained by RP-HPLC procedure. The most frequently subunits at Glu-A1 locus were N, at Glu-B1 locus 7+9 and at Glu-D1 locus 2+12. The cultivars with subunits 5+10 at Glu-D1 locus have shown, on the average, better technological characteristics in contrast to cultivars with subunits 2+12 at the same locus. The obtained correlation coefficients between technological properties and analysed gluten proteins reflected the different roles of specific gluten groups in defining of bredmaking quality. The cultivars Bezostaja (N 7+9 5+10), Divana (N 7+9 5+10), Ana (1 7+9 5+10), Srpanjka (N 7+8 2+12), Demetra (1 7+9 5+10), Žitarka (1 7+8 2+12), Klara (1 7+8 2+12) and Barbara (N 7+8 2+12) with optimal proportions of polimeric HMW glutenin subunits and lower Gli/Glu ratios were characterised as cultivars with very good and good breadmaking quality. The lower proportions of HMW glutenin subunits and higher proportions of monomeric gliadins, with consequently a higher Gli/Glu ratios, had negative influence on breadmaking quality of cultivars Monika (N 7+9 2+12), Kata (N 7+9 2+12), Libellula (1 20 2+12) and Sana (N 6+8 2+12).

The gluten proteins strongly affect the viscoelastic properties of dough. They consists of monomeric gliadins (alfa, beta, gamma and omega) characterized by intra-molecular disulphide bonds when present and polymeric glutenins formed by high (HMW-GS) and low (LMW-GS) molecular weights possessing both intra- and inter-chain bonds. In the group of polymeric glutenins the LMW-GSs play a key role in the glutenin polymer formation. They have been classified, according to their biochemical properties into B, C and D-types, with the B-types represented by a large number of subunits with apparent molecular weights ranging from 30.000 up to 70.000 and C- and D-types which consist of modified gliadins which have been incorporated into the glutenin polymer because possess an odd number of cysteine residue. On the basis of these different structural characteristics the LMW-GS can be classified as chain extenders and chain terminators. This complex protein mixture, composed by a high number of polypeptides differently assembled in the gluten polymers, and a corresponding high number of genes at Gli-1 and Glu-3 loci, have not been completely isolated and characterized. Recently, studies carried out on the B-, C- and D type LMW-GS present in hexaploid wheats, have demonstrated as electrophoretic and chromatographic techniques coupled with new techniques such as mass spectrometry represent efficient tools to characterize the gluten complex. In order to study the role of specific polypeptides and corresponding genes, as those included in the C glutenin fraction and to evaluate the effects produced by the loss of specific proteins on the functional properties of flour and semolina, total proteins extracted from different varieties and lines of tetraploid wheats, have been analysed by electrophoretic (SDS-PAGE) and chromatographic (RP-HPLC) techniques and polymerase chain reaction (PCR) using specific primers. In particular gliadin and glutenin fractions present in wild wheats T. dicoccoides, tetraploid wheats T. turanicum, T. polonicum, T. carthlicum, have been evaluated and compared to varieties and biotypes in order to identify genotypes with different allelic variants at Gli-B1/Glu-B3 loci. The LMW-GS fraction of above mentioned have been submitted to fractionated precipitation with hydro-alcoholic extracts to obtain enriched B and C-type LMW-GSs and subsequently analysed by RP-HPLC. Comparison of chromatograms have permitted a preliminary identification of B- and C-type LMW-GS, with the designation of corresponding genes, and of unknown putative C-type LMW-GSs in different tetraploid species included in the analyses. The structural/quantitative variation of the glutenin polymers in wheat semolina, induced by presence/absence of particular LMW-GS in particular genotypes and lines, will be also discussed.

Structural studies of the high molecular mass (HMM) glutenin subunits 1Bx7 (from cvs Hereward and Galatea) and 1Bx20 (from cv. Bidi17) of bread wheat were conducted using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and reversed-phase high-performance liquid chromatography/electrospray ionization mass spectrometry (RP-HPLC/ESI-MS). For all three proteins, MALDI-TOFMS analysis showed that the isolated fractions contained a second component with a mass about 650 Da lower than the major component. The testing and correction of the gene-derived amino acid sequences of the three proteins were performed by direct MALDI-TOFMS analysis of their tryptic peptide mixture. Analysis of the digest was performed by recording several MALDI mass spectra of the mixture at low, medium and high mass ranges, optimizing the matrix and the acquisition parameters for each mass range. Complementary data were obtained by RP-HPLC/ESI-MS analysis of the tryptic digest. This resulted in coverage of about 98% of the sequences. In contrast to the gene-derived data, the results obtained demonstrate the insertion of the sequence QPGQGQ between Trp716 and Gln717 of subunit 1Bx7 (cv. Galatea) and a possible single amino acid substitution within the T20 peptide of subunit 1Bx20. Moreover, the mass spectrometric data demonstrated that the lower mass components present in all the fractions correspond to the major components but lack about six amino acid residues, which are probably lost from the protein C-terminus. Finally, the results obtained provide evidence for the lack of glycosylation or other post-translational modifications of these subunits.

Wheat is one of the three most important crops in the world, together with maize and rice. Approximately 600 million tonnes are harvested annually with cultivation extending over a vast geographical area, from Scandinavia to Argentina, including higher elevations in the tropics. Although the ability to give high yields under a range of conditions has contributed to the success of wheat, the most important factor has been the unique properties of wheat dough which allow it to be processed into a range of foodstuffs, notably bread, other baked products, and pastas. These properties are usually described as viscoelasticity, with the balance between the extensibility and elasticity determining the end use quality. For example, highly elastic (‘strong’) doughs are required for breadmaking, but more extensible doughs for making cakes and biscuits. The viscoelastic properties of dough are determined by the grain proteins, and in particular by the storage proteins which form a network in the dough called gluten (Schofield, 1994). Consequently, the gluten proteins have been widely studied over a period exceeding 250 years to determine their structures and properties and to provide a basis for manipulating and improving end use quality (Shewry et al., 1995).

Publisher Summary This chapter discusses the gluten composition and properties. The chapter describes the basic information on the genetics, structure, and physics of gluten proteins. The different bakery applications of gluten, such as bread, biscuits/cookies, and pasta are discussed. The chapter also discusses the new area of non-food applications. Some examples describe how gluten functions are being used in new areas. Recommendations are given for future directions to further increase the use of this industrial protein. The chapter gives an overview of current-day gluten research, ranging from various food applications to more novel areas of non-food applications, where cereal science is less advanced. Cereals show a large variation in gluten properties, determined by both genetic and environmental factors. The cereal research has focused on unravelling these quality-function relations. The chapter discusses the problems of the definition of quality in a widely differing (product) context, and the complexity of the gluten protein network in relation to its physical behavior and its structure and composition.

The effect of transglutaminase in the presence of different commodity forms of animal protein on the aggregating ability of gluten, ion-binding ability of proteins in gluten-free flour was studied. Given that increase in the strength of the hydrate layer around the protein molecule allows to reach an increase in the aggregation stability of protein, it was considered appropriate to investigate the effect of additives on the aggregating ability of gluten. To prove the mechanism of interaction of additives with gluten-free flour, potentiometric titration method was used. Increase in the aggregating ability of gluten and ion-binding ability of flour proteins in the presence of the studied additives was proved. Nonadditive binding of hydrogen ions and hydroxyl ions by gluten-free flour proteins, which indicates the interactions among different proteins was found. Also, the peculiarities of the process of aggregation of gluten proteins in solution in the presence of the mentioned additives, which lie in increasing the overall degree of aggregation and its rate were determined. The results are aimed at improving the structural and mechanical properties of flour dough, pasta and flour formed products, gluten-free bread. Improved quality of gluten-free bread - a noticeable increase in the volume and porosity of bread, better shape and appearance was confirmed experimentally. Herewith, enzyme together with gelatin have the greatest impact. Also, the structural and mechanical properties of pasta dough and cooking properties of prepared pasta are improved.

Due to an increasing incidence of celiac disease (CD) and other gluten-related disorders, different gluten-free breads have been developed using starches and additives as a substitute for gluten. Thus, patients miss not only the taste and aroma of wheat bread but also risk their sensitive intestines. Therefore, modifying gluten to avoid an immune response in CD and its application to baking is in progress. The aim of the study was to enzymatically modify gluten on wheat flour, during bread-making avoiding the use of additives, to reduce immunoreactivity, preserving its properties. Microbial transglutaminase (mTG) or chymotrypsin (ChT) was used to bind lysine or valine to gluten proteins in a model system. The best conditions were directly applied to wheat flour for bread-making with and without punching at 45 min. Subsequently, the rheological properties of the doughs, specific volume of the loaves, immunoreactive gluten content and modification of the extracted proteins were evaluated. ChT-treated breads presented a better appearance with a more homogeneous crumb, higher specific volume values (3.34-4.25 cm(3) g(-1)) and higher reactive gluten reduction (up to 71%) than the mTG-treated ones (1.23-2.66 cm(3) g(-1)) with only a 42% reactive gluten reduction. Thus, transpeptidation during bread-making is a promising technology, although it is necessary to improve the modification process to obtain the reactive gluten reduction required in breads for the treatment of CD patients and other gluten-related disorders.

A characteristic feature of high molecular weight (HMW) subunits, as with many gluten proteins, is their large repetitive central domain. This consists of tandem and interspersed repeats based on two or three consensus motifs: a nonapeptide (Gly . T yr .T yr .Pro .Thr . S er .Pro/Leu. Gln. Gln), a hexapeptide (Pro .Gly . Gln. Gly . Gln. Gln) and, in the x-type subunits only, a tripeptide (Gly.Gln.Gln). Secondary structure prediction and spectroscopic studies of purified HMW subunits and short synthetic peptides based on the consensus repeat motifs have indicated that in solution the repetitive domain forms a loose spiral consisting of regularly repeated preverse turns’”. In the solid state numerous non-covalent intermolecular interactions exist. We have used Fourier-transform infrared spectroscopy to study perfect repeat peptides with different lengths in order to understand how this affects the molecular structures.

The protein content of wheat grains may vary between 10% and 18% of the total dry matter. Wheat proteins are classified according to their extractability and solubility in various solvents. Classification is based on the classic work of T.D. Osborne at the turn of the last century. In his procedure, sequential extraction of ground wheat grains results in the following protein fractions: albumins, which are soluble in water; globulins, which are insoluble in pure water but soluble in dilute NaC1 solutions, and insoluble at high NaC1 concentrations; gliadins, which are soluble in 70% ethyl alcohol, and; glutenins, which are soluble in dilute acid or sodium hydroxide solutions.