Measurement of Zeta Potential of Polysaccharides and Fabricating Polysaccharide-polysaccharide Nanotubes

Biopolymer nanotubes (BNTs) are two-open ended cylindrical structures which can be used for nanodevices, medicine, and biology. Especially, fabricating BNTs using proteins is suitable for biological and biomedical applications due to their safety and biocompatibility. This study has been focused on fabricating BNTs using polysaccharides which have been proved to be safe by the FDA and used in food applications. The zeta-potential, surface charge, of different polysaccharides was measured to find the region of stability and isoelectric point from pH 4 to 11 by DLS. Next, xanthan and chitosan have been selected for fabricating BNTs because of their stability and dispersibility compared to the other polysaccharides. Two polysaccharide solutions were adjusted to pH 4 where the charge difference was the largest; and BNTs were fabricated at different mass ratio using a template assisted layer-by-layer method. Then, SEM images were taken to visualize the nanotubes. As a result, some nanotubes were seen in the SEM images; however, they did not have the optimal well defined form yet. Also, there were too many clusters instead of individual clear nanotubes. The interaction and the size of the proteins might be too large, so the polysaccharides tended to form globular structures instead of nanotubes. To fabricate BNTs, xanthan will be hydrolyzed to reduce size, and the mass ratio would be also reduced to decrease the interaction between two polysaccharides

Glutaraldehyde Crosslinked Zein Solutions Make Better Biodegradable Films

The corn protein, zein, is a byproduct of the ethanol production industry. Recently, zein has been used in the production of films and food packaging due to its biodegradability, low production cost, and abundance of corn in the United States. To improve overall quality of zein films, the mechanical properties and surface properties should be enhanced. Therefore, in this study, our aim is to improve the properties of zein films with glutaraldehyde (GDA) as a crosslinker. Zein was solubilized and mixed with 70% ethanol and GDA, then sonicated. Solutions were poured onto different surface materials, including polydimethylsiloxane (PDMS), polystyrene (PS), and glass petri dishes to create films. Cast solutions were placed in the oven for different length of time (i.e. 0 hour, 1 day, 3 day, etc). Water contact angle and FTIR measurements were conducted to understand the crosslinking mechanism of zein films and surface properties of zein to understand how it will perform. Measurements from water contact angle and FTIR showed changes caused by heating, with 6% GDA films having less increase in hydrophobicity than films with 0% GDA and the changes in the ratio of -helices and -sheet structures of zein as the duration of heating was increased. Casting zein films on different surfaces affected the hydrophobicity of films that were not heated, but films that were heated for 3 days in the oven did not have any significant differences

Formation of Lactalbumin Nanoparticles by Desolvation Method

Protein nanoparticles are ideal carriers for bioactive compounds such as nutraceuticals and drugs because they are biodegradable, less immunogenic and non-toxic and can be nanoparticulated. This study focuses on the desolvation method to form lactalbumin protein nanoparticles. Lactalbumin is soluble in water and insoluble in many organic solvents. Different solvent/non-solvent ratios are evaluated in this research project for the effect they have on the size, PDI and stability of protein nanoparticles. Different methods including sonication and centrifugation were used and compared in terms of their effectiveness to produce small nanoparticles during fabrication of the nanoparticles. Data collected including protein nanoparticles average size and zeta potential, also SEM and TEM images were used to study the nanoparticles. It was found that high non-solvent ratio can significantly decrease the average particle size, while it also causes an increase in polydispersity index. Sonication can cause some aggregation of the nanoparticles and makes the average particle size slightly increase. Centrifugation can precipitate the large particles and when the supernatant is collected the average particle size is much smaller. These measurement will contribute to the further understanding of the formation of high quality protein nanoparticles that can serve as efficient drug carriers

The SAOS, MAOS and LAOS behavior of a concentrated suspension of tomato paste and its prediction using the Bird-Carreau (SAOS) and Giesekus models (MAOS-LAOS)

The SAOS and LAOS behavior of tomato paste were investigated in this study. SAOS rheology was well predicted by the semi-empirical Bird-Carreau constitutive model. The LAOS (Large amplitude oscillatory shear) behavior of tomato paste was also investigated in depth in this study and non-linear rheological properties were obtained by utilizing Ewoldt-McKinley theory. These parameters offer new insights into the rheology of tomato paste and help understand structural changes which occur at different deformations (strain) and time scales (frequency). We plotted the intracycle normalized stress vs. normalized strain in the linear and non-linear regions offered new intracycle insights and observations. Tomato paste showed an irreversible structural change in LAOS evidenced by strain softening (in the mid-oscillatory region) followed by strain hardening (in the large oscillatory region). The nonlinear flow behavior simulated by the single mode Giesekus model gave good results up to moderate strains and frequencies. These results help gain better insights at large deformations, which occur during processing and consumption

Non-linear rheological behavior of gluten-free flour doughs and correlations of LAOS parameters with gluten-free bread properties

WOS: 000399267000005Predicting loaf volume development of gluten free baked products to have similar properties to wheat products remains a challenge and there is no good marker for loaf volume. Large Amplitude Oscillatory Shear (LAOS) flow experiments and baking tests were conducted on rice, buckwheat, quinoa, and soy flour doughs to understand if there is any correlation between the non-linear rheological properties and loaf volume. The challenging water absorption capacities were determined by matching the eta* vs. frequency data of the gluten free flours with that of the soft wheat flour dough with moisture content at 500 BU. 110%, 90%, 85%, and 160% water levels were found as optimal for rice, buckwheat, quinoa, and soy flour, respectively. The comparison of elastic Lissajous-Bowditch curves showed that the stronger nonlinearities were seen at low frequencies and the wider the loop, the weaker the structure and the more structural breakdown with an order of soft wheat, soy, buckwheat, quinoa and rice flour doughs. Secondary loops have been observed in viscous Lissajous-Bowditch curves which are related to the strong non-linearities in elastic stress. The distributions of elastic and viscous LAOS parameters showed that soy dough has the closest rheological performance to wheat dough among other dough samples, which has the highest protein content. G(L)'. and G(M)' values at 10 rad/s and 200% strain showed the best correlation among all LAOS parameters with the loaf volume. The strain stiffening/softening property e(3)/e(1) complemented the mechanistic explanations which were offered using G(L)' and G(M)' values. (C) 2017 Elsevier Ltd. All rights reserved

NON-LINEAR RHEOLOGICAL PROPERTIES OF SOFT WHEAT FLOUR DOUGH AT DIFFERENT STAGES OF FARINOGRAPH MIXING

WOS: 000386873100001During mixing of wheat flour doughs, the distribution of the gluten network changes as a result of continuously applied large deformations. Especially gliadin, changes its distribution in the whole network during mixing. It is possible to fundamentally explain the role of molecular changes in more detail using large amplitude oscillatory measurements (LAOS) in the non-linear region. Therefore, the purpose of this study is to understand the effect of mixing on the non-linear fundamental rheological behavior of soft wheat flour dough using LAOS. Dough samples were obtained at 4 different phases of the Farinograph mixing and LAOS tests were done on each of them. LAOS tets give in depth intracycle understanding of rheology. All samples showed strain stiffening S and shear thinning T behavior at large strains previously not known in the cereal rheology community. Increasing mixing time (phase 1 to phase 4) and decreasing frequency resulted in retardation in the break of strain stiffening as strain increases. The strain stiffening behavior started to decrease for the dough samples at the 3rd and the 4th phases of mixing. LAOS data enabled us to describe the non-linear rheological changes occurring both in the viscous part largely attributed to the starch matrix and elastic part largely attributed to the gluten network components of the soft wheat flour dough under large deformations.USDA Hatch funds; William R. Scholle Foundation; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This research was partly funded by USDA Hatch funds, the William R. Scholle Foundation, a Fellowship to Gamze Yazar from The Scientific and Technological Research Council of Turkey (TUBITAK). The authors gratefully acknowledge all of these funding sources which made this research possible

LAOS behavior of the two main gluten fractions: Gliadin and glutenin

WOS: 000415782300028Crude gliadin and glutenin fractions were studied using Large Amplitude Oscillatory measurements. LAOS measurements were carried out at three different frequencies (20, 10, 1 rad/sec) between the strain values of 0.01-200%. The beginning of non-linearity for glutenin occurred at similar to 2.5%, while an initial region of strain hardening was observed for gliadin (2.5-10%) at 1 rad/sec frequency and up to 15% at the higher frequencies applied. Lissajous curves showed in the elastic analysis of both fractions glutenin was more elastically dominated since Lissajous curves were narrower, while for gliadin the ellipses were much broader suggesting more fluid-like behavior and each ellipse depended on the magnitude of frequency. Decreasing frequency increased the viscous behavior of both glutenin and gliadin in the non-linear region, but the change in gliadin was much more pronounced. Gliadin molecules only display intramolecular disulfide bonds creating a great deal of mobility whereas for glutenin molecules, which contain both intermolecular and intramolecular disulfide bonds, the strong network structure formed by this molecular arrangement results in very pronounced strain stiffening. (C) 2017 Elsevier Ltd. All rights reserved

Effect of mixing on LAOS properties of hard wheat flour dough

WOS: 000382349300022Large Amplitude Oscillatory Shear (LAOS) tests were conducted at strains ranging from 0.01% to 200% and different frequencies (20, 10, 1, and 0.1 rad/sec) on hard wheat flour dough samples obtained from the different phases of Farinograph mixing: 1) at the first peak, 2) 5 min after the first peak, 3) 12 min after the first peak, 4) at the 20th min. All samples showed strain stiffening and shear thinning behavior in large strains. The gluten network is the origin of strain stiffening behavior and the rearrangement of the suspended starch matrix is the origin of shear thinning behavior. LAOS enables us to independently deconvolute these two events offering new insights into the structural origins of rheological properties in the non-linear region. Dough samples started to show strain softening and shear thickening after giving a peak around 100% strain due to the onset of the breakdown of the gluten network. (C) 2016 Elsevier Ltd. All rights reserved.USDA Hatch funds; William R. Scholle Foundation; Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This research was partly funded by USDA Hatch funds, the William R. Scholle Foundation, a Fellowship to Gamze Yazar from The Scientific and Technological Research Council of Turkey (TUBITAK). The authors gratefully acknowledge all of these funding sources which made this research possible

Distribution and location of ethanol soluble proteins (Osborne gliadin) as a function of mixing time in strong wheat flour dough using quantum dots as a labeling tool with confocal laser scanning microscopy

WOS: 000347264100032Gliadin is the more fluid of the two major classes of proteins, gliadins and glutenins, in wheat flour dough and flows best among these two protein classes. Glutenins because of their high elasticity and high hydrophobicity are not likely to disperse as well as gliadins especially if gliadins are not well dispersed or are not present in the dough matrix. The role of native gliadin in this networking process is not well understood and has not been studied by prior researchers due to unavailability of molecular tools to specifically probe gliadin behavior until now. Gliadins contribute to the viscosity and extensibility in dough. In this study, the distribution and location of ethanol soluble proteins (Osborne gliadins) as a function of mixing time in a Brabender Farinograph for model wheat flour dough were investigated for the first time using confocal laser scanning microscopy (CLSM). Gliadin proteins were tagged with water soluble, biocompatible amine derivatized polyethylene glycol functionalized quantum dots to increase the clarity and specificity of imaging. The effect of different mixing conditions on the distribution of ethanol soluble proteins (Osborne gliadins) and their role in building dough structure was investigated. The chosen mixing times were arrival time (AT), peak time (PT), departure time (DT) and breakdown time (10 min after departure time). Location and distribution of gliadins were investigated in AT, PT, DT and 10 min after departure time. Antibody quantum dot (QD) mixture successfully bonded to gliadins located on dough sections. The specificity of gliadin antibody to ethanol soluble proteins (Osborne gliadins) was shown successfully with a Western Blot experiment excluding binding to all other hard wheat flour proteins. The images obtained from dough sections were bright and clear and allowed to distinguish gliadin easily. Mixing led to considerable changes in the distribution, average partide size, and number of particle count of gliadins in dough microstructure. The QDs were found to be localized not only around the air cells as indicated by higher intensities but also in the bulk dough. Quantum dots can be used as fluorophore probes to tag and track molecules of interest in food microstructure. This combined with immunohistochemistry techniques offers a better understanding of gliadin distribution in dough during mixing. (C) 2014 Elsevier Ltd. All rights reserved.Ministry of Education scholarship - Turkish GovernmentMinistry of National Education - Turkey; State of Illinois; USDA Hatch fundsThe authors particularly thank Dr. Sivaguru Mayandi for his technical assistance for the use of confocal laser microscopy leading to the visualization of quantum dots in dough samples by CSLM and analyzing the data accurately. Fatih Bozkurt would also like to thank Dr. Peter Yau from the Department of Chemistry at the University of Illinois for welcoming him to his lab and helping him purify the antibody. We are also deeply grateful to Dr. Nesli Sozer currently at VU Finland for sharing her knowledge about quantum dots in the early stages of this study. Fatih Bozkurt was supported by a Ministry of Education scholarship awarded by the Turkish Government. The research was supported by State of Illinois and USDA Hatch funds