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The aim of this study was to investigate the gelation process of binary mixes of pumpkin-seed and egg-white proteins. The substitution of pumpkin-seed proteins with egg-white proteins improved the rheological properties of the obtained gels, i.e., a higher storage modulus, lower tangent delta, and larger ultrasound viscosity and hardness. Gels with a larger egg-white protein content were more elastic and more resistant to breaking structure. A higher concentration of pumpkin-seed protein changed the gel microstructure to a rougher and more particulate one. The microstructure was less homogenous, with a tendency to break at the pumpkin/egg-white protein gel interface. The decrease in the intensity of the amide II band with an increase in the pumpkin-seed protein concentration showed that the secondary structure of this protein evolved more toward a linear amino acid chain compared with the egg-white protein, which could have an impact on the microstructure. The supplementation of pumpkin-seed proteins with egg-white proteins caused a decrease in water activity from 0.985 to 0.928, which had important implications for the microbiological stability of the obtained gels. Strong correlations were found between the water activity and rheological properties of the gels; an improvement of their rheological properties resulted in a decrease in water activity. The supplementation of pumpkin-seed proteins with egg-white proteins resulted in more homogenous gels with a stronger microstructure and better water binding.

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The potential for enhancing the spring wheat protein content by different cultivation strategies was explored. The influence of ultrasound on the surface and rheological properties of wheat-gluten was also studied. Spring wheat was cultivated over the period of 2018-2020 using two farming systems (conventional and organic) and five forecrops (sugar beet, spring barley, red clover, winter wheat, or oat). The obtained gluten was sonicated using the ultrasonic scrubber. For all organically grown wheat, the protein content was higher than for the conventional one. There was no correlation between the rheological properties of gluten and the protein content in the grain. Gluten derived from organically grown wheat was more elastic than those derived from the conventional one. Sonication enhanced the elasticity of gluten. The sonication effect was influenced by the forecrops. The most elastic gluten after sonication was found for organic barley and sugar beet. The lowest values of tan (delta) were noted for conventional wheat and conventional oat. Cultivation in the monoculture gave gluten with a smaller susceptibility to increase elasticity after sonic treatment. Sonication promoted the cross-linking of protein molecules and induced a more hydrophobic character, which was confirmed by an increment in contact angles (CAs). Most of the organically grown wheat samples showed a lower CA than the conventional ones, which indicated a less hydrophobic character. The gluten surface became rougher with the sonication, regardless of the farming system and applied forecrops. Sonication treatment of gluten proteins rearranged the intermolecular linkages, especially disulfide and hydrophobic bonds, leading to changes in their surface morphology.

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Grain hardness is the single most important trait in determining technological properties and end-use quality of wheat product. This trait is controlled by two genes (Pina-D1 and Pinb-D1) at the Hardness (Ha) locus. Soft endosperm kernels are characterized by the presence of alleles 'a' in both genes (Pina-D1a and Pinb-D1a), while the medium hard and hard grain is the result of deletion in the Pina-D1 gene or single mutation of the Pinb-D1 gene. The aim of the current study was to determine the relationship between common wheat grain hardness and the presence of puroindoline genes. Eighty-one spring common wheat cultivars from Europe were analysed for grain hardness by SKCS (Single Kernel Characterization System) and Pin-D1 genes. The analysed genotypes were divided into three hardness classes: hard, medium and soft and they showed four allelic combinations in Pin-D1 genes. The SKCS results showed that hard wheat was the major type in European cultivars, whereas molecular analysis showed differential allelic combinations of puroindoline genes among these classes. The conducted analyses suggest that another major gene or other factors were influencing kernel texture. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-02897-3.

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Gelatin solution was added to the gluten dispersion to obtain 25% protein from gluten and 0, 0.3, 0.6 and 1.0% of gelatin. Heat-induced gels were formed. The gelatin was leached by immersing the gel straps in distilled water at 45 °C for 2 h. Incorporation of gelatin into the gluten gel matrix resulted in its strengthening. Increase in elastic properties with the increasing amount of gelatin was also found for the macerated gels. The tangent delta showed the minimum for the leached gel with the initial concentration of gelatin 0.6%, so probably at this concentration there was some reinforcement of gluten, or the structure of gluten matrix was formed with the best ability to include gelatin inside. FTIR (Fourier transform infrared spectroscopy) results showed, that at the 0.6% gelatin concentration more gelatin was present in the leached samples than in the 1% gelatin added samples. Gelatin gels can act as an active filler reinforcing the gluten microstructure. Leaching of gelatin from the mixed gel matrix resulted in the microstructure with visible phase separation. Generally gelatin addition gave a surface smoothing effect and lower surface roughness of the obtained gels. Pure gluten gels soaking in hot water resulted in the decreased roughness. Possibility of manipulation with gluten gels surface roughness by co-gelling with gelatin can have an influence on the application of such gels as matrices for active ingredients.

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Gluten-free bread making success is closely linked to the biophysical behaviour of dough. Quality of these doughs is largely determined by the properties of their proteins and starch. This study aimed to explain, at the structural level the rheological behaviour of gluten-free rice-field bean dough compared to that of soft wheat. The conformational aspects of proteins and starch were studied using Fourier transformed infrared spectroscopy (FT-IR). Doughs of soft wheat, rice, field bean, mixture of rice-field bean flour and the same mixture where a portion of rice flour underwent hydrothermal treatment were studied. The results show that viscous and viscoelastic components of gluten-free doughs were changed by supplementation of rice with field bean flour. Most of gluten-free doughs possessed a higher storage modulus in comparison with soft wheat dough. Analysis of FT-IR spectra in the amide I region conveyed to find the differences relative to soft wheat flour dough showed that in non-gluten doughs the increase in ß-sheet content was observed at the expense of ß-turns. These results were confirmed by amide I deconvolution. Gluten-free doughs contained more ß-sheet structure as compared to soft wheat dough and less ß-turns inducing high structuralization level that characterized this type of dough matrix. Concerning starch, the supplementation with rice-field bean generated the reorganization of field bean and rice doughs starches approaching that of wheat dough.

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Relations between sensory perception, extrusion and fracture in shear, extension and compression are examined. Gelatin-based gels are perceived as less firm and less hard than expected based on their mechanical properties compared to polysaccharide gels that have the same mechanical properties at room temperature but melt well above body temperature, underlying the importance of the measurement temperature for gels that melt during mastication. Correlations between parameters from extrusion and compression, extension and shear are verified using mixed polysaccharide gels. PRACTICAL APPLICATIONS: We previously reported a high correlation between several sensory attributes and parameters from an extrusion test. The extrusion test showed the most robust correlation, and could be used to assess samples at both extremes of the texture range with respect to elasticity, for example, both samples that could not be extended as their very low elasticity led to their fracture during handling, as well as samples that could not be fractured in compression. Here, we reexamine the validity of the relations reported. We demonstrate the generality of the relations between large deformation tests and extrusion, but the findings underscore the need to take into account the measurement temperature for samples that melt during mastication when correlating instrumental parameters with sensory perception.

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Aerated whey protein gels were formed using calcium chloride, magnesium chloride or iron (II) chloride induced gelation of pre-denatured protein dispersions. The structure of the obtained gel surface depends on the type and concentration of added salt. Higher cation concentration produced gels a with higher quadratic mean of the surface roughness and maximum roughness height. Aerated gels of optimal properties for retaining air bubbles were characterized by similar surface roughness. The surface topography is mainly responsible for changes in the wettability. The contact angle of the probe liquid sample depends on the liquid surface tension components. An approach based on the contact angle hysteresis (CAH) is suitable for determining the total value of the apparent surface free energy of such materials. An approach based on the components of apparent surface free energy (LWAB) only allows the calculation of the dispersion component and electron donor parameter of energy in the case of added magnesium and iron salt. Wettability, depending on the nature of the surface, can be described for the hydrophilic surface by the Wenzel model, and for the hydrophobic surface by the Cassie - Baxter model.

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The aim of the research was to form mixed cellulose/egg white isolate (EWI) fibers. Cellulose was dissolved in the Schweitzer's reagent. The blend fibers were obtained by simultaneous cellulose fiber formation and acid-induced gelation of EWI in 33% sulphuric acid solution. Increased storage modulus was noted for the blend fibers in comparison to the cellulose fibers. EWI alone formed fibers which were composed of microfibers with the average diameter of about 80 nm. Cellulose fibers had a loose microstructure with about 10 µm gaps and rough surface. The addition of EWI caused that the surface of the fiber was even more rough with a tendency to form microfibers, which were not observed for cellulose alone. EWI protein molecules had the tendency to bridge the voids between cellulose microfibers. Protein in the blend fibrils formed more branched aggregates than in the EWI fibrils, which was probably caused by interactions with copper ions. Both in cellulose and cellulose/EWI fibrils, the cellulose crystallized in cellulose II monoclinic system. Reduction in COH groups was noted, which was probably caused by interactions between the cellulose and proteins molecules. EWI/cellulose interactions caused formation of ß-sheet type structures.

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