Master of Science / Department of Grain Science and Industry / Jon M. Faubion / Charles E. Walker / In commercial bakeries, the baker expects to get the same bread loaf, including weight and size, after sheeting the same size dough piece. Doughs made from different flours have different elastic recoveries to a great extent, which has an effect on the dough’s size and density. Products made from differently elastic doughs can’t have the same shape and height. Weight may also be affected. The dough rheological behaviors of five flours and their blends having different chemical and physical properties were measured as were changes in thickness and snapback (thickness of the machined dough sheet relative to the roll gap) immediately following sheeting. Dough snapback was determined to be a function of both processing parameters, reduction ratio, and dough rest time, as well as different flour properties. The predication equation for dough snapback is based on multiple flour properties and sheeting conditions. Among the variables, Mixograph work, reduction ratio, and dough rest time were the main factors affecting the elastic characteristics of the doughs. Minimum snapback occurred with the weakest flour experiencing the longest rest time and the smallest reduction ratio. A 7-factor equation was found to be robust to predict the snapback of several flours, by combining Mixograph work, reduction ratio, dough rest time, Mixograph peak height and mixing time, Alveograph P/L, and protein content.

The objective of this study was to evaluate the reduction on the levels of mycotoxins in wheat products and by-products: deoxynivalenol (DON) in whole wheat flour, wheat bran and the efluent from wet milling of wheat flour, and zearalenone (ZEN) in wheat bran. Firstly, the reduction of DON contamination was studied on whole wheat flour, naturaly contaminated, and considering different moisture levels, as well as in wet milling effluent of wheat flour. Further, the impact of the ozonation process on the rheological properties of the processed flour was evaluated. Secondly, the wheat bran naturally co-contaminated with DON and ZEN was studied, considering the degradation of both mycotoxins and the impact of the ozonation process on the bran phenolic compound content and on the antioxidant capacity. The DON degradation in the whole wheat flour increased with both processing time and moisture content. By changing these process parameters, it was possible to obtain products in accordance with the legal limits of Brazil and the European Union, even starting with concentration 2-4 times higher than the legal limits. However, the rheological properties of the whole wheat flour were affected by the process, probably due to protein modifications. The DON concentration on the wet milling effluent was linearly reduced by the ozonation. In wheat bran naturally contaminated and in its equilibrium moisture, the ozonation reduced both DON and ZEN contamination. The degradation of ZEN was higher and faster than the degradation of DON, which could be explained by their molecular structures. It was also observed that the ozonation process did not negatively affect the phenolic compounds and the antioxidant capacity, which is high desirable from a nutritional point of view. Consequently, this work concludes that the ozonation process was effective in reducing DON and ZEN in different wheat products and efluent. It is noteworthy that the results obtained are promising for future studies and to elucidate the mechanism of action of ozone on mycotoxins and constituents of food. / O objetivo deste estudo foi avaliar a redução nos níveis de micotoxinas em produtos e subprodutos de trigo: desoxinivalenol (DON) em farinha de trigo integral, farelo de trigo e efluente de moagem da farinha de trigo e zearalenona (ZEA) em farelo de trigo. No primeiro momento, a redução da contaminação por DON foi estudada em farinha de trigo integral, naturalmente contaminada e considerando diferentes níveis de umidade, bem como no efluente de moagem úmida da farinha. Além disso, o impacto do processo de ozonização nas propriedades reológicas da farinha processada foi avaliado. Em segundo lugar, estudou-se o farelo de trigo naturalmente co-contaminado com DON e ZEA, considerando a degradação de ambas as micotoxinas e o impacto do processo de ozonização no conteúdo do composto fenólico do farelo e na capacidade antioxidante. A degradação de DON na farinha de trigo integral aumentou tanto com o tempo de processamento quanto com o teor de umidade. Ao alterar esses parâmetros de processo, foi possível obter produtos de acordo com os limites legais do Brasil e da União Européia, mesmo com a concentração 2-4 vezes superior aos limites legais. Contudo, as propriedades reológicas da farinha de trigo integral foram afetadas pelo processo, provavelmente devido a modificações de proteínas. A concentração de DON no efluente de moagem úmida foi linearmente reduzida pela ozonização. Em farelo de trigo naturalmente contaminado e em sua umidade de equilíbrio, a ozonização reduziu a contaminação DON e ZEA. A degradação do ZEA foi maior e mais rápida que a degradação do DON, o que poderia ser explicado pelas suas estruturas moleculares. Observou-se também que o processo de ozonização não afetou negativamente os compostos fenólicos e a capacidade antioxidante, o que é altamente desejável do ponto de vista nutricional. Consequentemente, este trabalho conclui que o processo de ozonização foi efetivo na redução de DON e ZEA em diferentes produtos de trigo e efluentes. Vale ressaltar que os resultados obtidos são promissores para futuros estudos e elucidar o mecanismo de ação do ozônio sobre micotoxinas e constituintes dos alimentos.

Probiotic bacteria are live microorganisms, which manifest health benefits in humans. The goal of this work was to characterize rheological properties of probiotic bacteria (Lactobacillus reuteri) formulation in which maltodextrin and sucrose used as excipients. To fulfil the goal, first, thermal, structural and rheological properties of maltodextrin, sucrose solutions and probiotic bacteria slurry were investigated. Probiotic bacteria formulations were prepared by adding probiotic bacteria slurry to maltodextrin and sucrose solutions at different mass fractions. Finally, rheological properties of probiotic bacteria formulations were evaluated. From TGA, the water content of PB slurry including intracellular water found 81%. In DLS, three different types of aggregations of maltodextrin were observed and characteristic size of Probiotic bacteria found 1μm. The optical microscopy results indicate that at the liquid - air interface and in dehydrated state the bacteria are birefringent and arranged in an ordered fashion resembling a nematic phase. Most of the MD, SU and MD+SU solutions show Newtonian behaviour. MD and SU solutions show strong increase of viscosity with increasing concentration. This dependence can be described by using the Spurlin–Martin–Tennent’s model. The viscosities of MD+SU solutions increase with increasing proportion of maltodextrin. The oscillation data of MD and MD+SU solutions can be described by Maxwell model. The viscosities of MD, SU, MD+SU mixed solutions decrease with increasing temperature. This temperature dependency can be described by Arrhenius model of viscosity. At very high concentrations of MD, a deviation from this behaviour is observed. The probiotic bacteria slurry shows shear thinning behaviour at low shear stress and Newtonian behaviour at higher stresses. All probiotic formulations in which probiotic bacteria dispersed in maltodextrin and sucrose solutions show Newtonian behaviour. The viscosities of maltodextrin solutions and MD+SU mixed solutions decrease by addition of probiotic bacteria whereas mixed effects of probiotic bacteria addition on the viscosity of sucrose solutions were observed. The viscosity of probiotic bacteria slurry decreases with increasing temperature, although deviations from this behavior are seen at certain conditions.

The thesis deals with HDPE modification by crosslinking. In the theoretical part, data available in the literature were reviewed. Modifications of the selected HDPE copolymer grade were carried out in a kneading device Brabender using 25 ml chamber size. After having optimized process conditions, there were performed a series of experiments in dependence on concentration of the initiator. Reological properties of polymer samples were investigated by melt flow indexes measured under different conditions. Changes in crystallinity and melting temperatures were evaluated from DSC heat flow measurements. The samples meeting characteristics supposed were selected for measuring complex viscosity on the Rheometer AR-G2 TA and for testing some mechanical properties on the device Zwick.

Yes / The principal aim of this paper is to investigate the effect of sand grading, surface morphology, and content on the rheological properties—that is, yield stress and plastic viscosity—of fresh mortar. Mortars were produced from four different types of sand at two volumetric cement-sand ratios of 1/0.9 and 1/0.6. Each blend was prepared with five water-cement ratios of 0.60, 0.55, 0.50, 0.45, and 0.40. The rheometer was used to determine yield stress and plastic viscosity parameters of each cement paste and mortar. Test results show that the relative yield stress and plastic viscosity of mortar to cement paste is inversely proportional to the excess paste thickness up to low values, below which the surface texture of sand particles becomes significant.

This study seeks to develop smart hydrogel formulations for injectable controlled drug delivery from Pluronics to enhance patients compliance, decrease side effects, reduce dose and frequency. A biocompatible copolymer, Pluronic F127 was probed as the main ingredient for the injectable systems owing its low gelation concentration and ease of modification the system properties through excipients addition. The matrix properties were studied through a series of thermal, rheological and structural (SAXS/SANS) experiments as a function of concentration and shear rate, covering both static and dynamic environments. It has shown that gelled viscosity (and structure) can be critically controlled by shear rate and the structures recorded do not match those predicted for sheared colloids. Two further Pluronics F68 and F108, were studied showing similar but shifted gelation properties to F127. Effects of additives were studied by introducing different Mw PEGs and a model hydrophobic drug ‘ibuprofen’ to a F127 20% formulation. PEGs addition effects on the system properties and gelation transition were largely dependent on the Mw used in the blend, which became more prominent with increasing chain length. Ibuprofen’s addition has resulted in reduced gelation temperature and smaller hard spheres without having a great effect on the system rheological properties compared to neat gels. Blends containing both additives PEG and ibuprofen exhibited a synergistic effect, where comparisons show that Ibuprofen had the largest effect on the blends lowering gelation boundaries and slightly increasing the size of the hard spheres indicating the necessity of full characterisation of the formulation with any API.

Workability has traditionally been used as one of the measures for controlling concrete mixture proportioning. This metric has provided limits on the water content in the concrete mixture for given aggregate size and type. The slump test, which is commonly used as an assessment of workability, is not adequate for characterizing the flow behaviour / rheology of fresh concrete. Studies have shown that Bingham's rheological properties, namely yield stress and plastic viscosity, provide good description of the flow behaviour of fresh concrete. In this thesis, an experimental program was designed on the basis of factorial design to evaluate the method of Cement Association of Canada for designing and controlling concrete mixture. The variables included in the mix design are water-cement ratio, water content, coarse aggregate size, silica fume, slag and bulk volume of coarse aggregate. In addition, Neuro-Fuzzy network has been adopted to correlate the current mixture proportioning method to the rheological properties of concrete. The network was constructed using experimental data tested in this study. Such correlation allowed the determination of water-cement ratio, water content, fine aggregate and coarse aggregate from compressive strength, yield stress and plastic viscosity. / Thesis / Master of Applied Science (MASc)

Flaxseed (Linum usitatissimum L.) gum (FG) is a material with many potential food and non-food applications. Consistent performance is critical for FG utilization and this is possible through selection of genotype, characterization and optimization of constituents, and chemical modification. Physico-chemical and functional properties of FG aqueous solutions from six Canadian flaxseed cultivars were investigated. FG yield, carbohydrate composition, protein content, and zeta potential (ζ) varied among these cultivars. FG solution properties were also affected by temperature, solution pH, NaCl concentration, and sucrose concentration. Detailed studies were conducted on CDC Bethune FG (FGB) proteins that were separated by 2D-gel electrophoresis. Conlinin was identified as the major protein. Protease treatment decreased FGB solution emulsification properties suggesting that conlinin might enhance emulsification. Formation of BSA-FGB coacervates was monitored by turbidimetric analysis as a function of solution pH, biopolymer mixing ratio, NaCl and urea. Coacervates were stabilized primarily by attractive electrostatic forces and secondarily by hydrogen bonds. Further, anionic carboxymethyl ether moieties were introduced to FGB structure through ether forming reactions using monochloroacetic acid (MCA) to produce products with uniform properties. The highest degree of substitution (DS) was obtained at 70 °C, 7.0 M NaOH, and a molar ratio of MCA to FGB of 10:1 over 3 h. Carboxymethylated FGB (CMFG) exhibited both modified surface morphology and thermal behaviour. Solutions of CMFG demonstrated shear-thinning behaviour and apparent viscosity decreased with increased DS. A more liquid-like flow behaviour was observed for CMFG as DS increased. Findings here will introduce and expand FG applications in food or related fields with targeted performance.

The effects of oxidation by sodium hypochlorite (0, 0.8, 2, and 5%, NaOCl), the presence of endogenous proteins, and amylose content on waxy and common rice flours (WF, CF) and starches (WS, CS) were investigated in terms of in vitro starch digestibility, morphology and surface properties, and thermal and rheological characteristics. The concentration of NaOCl had an effect on all the samples including WF, CF, WS, and CS. The carbonyl and carboxyl group contents increased up to 25 and 10 folds (P < 0.05) of oxidized starches (WS, CS), respectively. Only mild oxidation (P < 0.05) occurred in flours (WF, WS). In addition, endogenous proteins were oxidized according to amino acid analysis and SDS–PAGE results. Glu+Gln, Gly, His, Arg, Tyr, and Lys were more sensitive to NaOCl oxidation. Disulfide bonds, hydrophobic force, and hydrogen bonds were involved in protein polymerization after NaOCl oxidative modification. In granular state, the in vitro starch digestibility of WF, WS, and CS decreased by 5% NaOCl oxidation. After gelatinization, only 2 and 5% oxidized WS had lower digestibility. Scanning electron microscopy and confocal laser scanning microscopy further demonstrated that protein existed on the surface of starch granules and had aggregation by oxidation. X-ray diffraction patterns showed the crystallinity of 5% oxidized flours and starches was reduced compared with all their non-oxidized samples. Thermal and rheological properties were analyzed by differential scanning calorimetry and rheometer, respectively. Starch gelatinization peak temperature of flours (WF, RF) was increased by 3 °C, but starches (WS, CS) had a significantly decrease by 8 °C. Viscoelastic patterns were dramatically changed by oxidation. Oxidized WF and CF had increased in both viscosity and elasticity by oxidation, whereas both WS and CS had significantly lower viscoelasticity after oxidative modification.

Baigiamojo magistro darbo tikslas – ištirti cheminių įmaišų poveikį reologinėms portlandcemenčio tešlos savybėms, panaudojant skirtingų tipų cementus. Darbe išnagrinėta lietuvių, užsienio mokslinė literatūra, aprašytos naudotos žaliavos, parinktos skirtingos cementinės tešlos sudėtys, kurios skiriasi cemento ir plastifikuojančios įmaišos tipu. Tyrimams naudotos šios medžiagos: AB „Akmenės cementas“ gamyklos portlandcementis CEM I 42,5 (N ir R ankstyvojo stiprumo), klinties portlandcementis CEM II/A-LL 42,5 N, plastiklis Centrament N3, naujausios kartos superplastiklis MC-PowerFlow 3140 ir vanduo. Ištirtas plastiklio ir superplastiklio poveikis portlandcemenčio tešlos vandens ir cemento (V/C) santykio pokyčiams ir sklidumui naudojant Sutardo viskozimetrą. Buvo tiriamos vienodo vandens ir cemento santykio portlandcemenčio tešlos su cheminėmis įmaišomis ir be jų. Tyrimai atlikti naudojant rotacinį viskozimetrą Rheotest NH 4.1 su bendraašiais cilindrais. Nustatytas cheminių įmaišų portlandcemenčio tešloje veiksmingumas, esant skirtingo tipo cementui. Pastebėta, kad portlandcemenčio tešlos dinaminis klampis gali būti reguliuojamas cheminėmis įmaišomis viso indukcinio hidratacijos periodo metu. Sukurta metodika portlandcemenčio tešlos reologinėms savybėms nustatyti bei parinktas reologinis modelis, kuris geriausiai apibūdina gautus tyrimų duomenis. Atlikus portlandcemenčio tešlos su cheminėmis įmaišomis ir be jų tyrimų rezultatų regresinę analizę, gautos klampio, tekėjimo lygtys... [toliau žr. visą tekstą] / The purpose of this thesis is to analyse the influence of chemical admixtures on the rheological properties of Portland cement paste, which differ depending on the type of cement used. In addition to the literature analysis, different cement paste compositions (differing in type of cement and plasticizers) were tested. Testing materials: Portland cement CEM I 42.5 (N and R early strength), limestone Portland cement CEM II/A-LL 42.5 N, plasticizer Centrament N3, the latest generation superplasticizer MC-PowerFlow 3140 and water. Research focused on effects of plasticizer and superplasticizer on water and cement (W/C) ratio and Portland cement paste slump-flow characteristics. Portland cement pastes with the same water-cement ratio with and without chemical admixtures were tested. Tests were carried out using a Suttard viscometer and rotation viscometer Rheotest NH 4.1 with coaxial cylinders. It was observed that viscosity of Portland cement paste can be controlled by chemical admixtures during the hydration induction period. The work provides analysis of the effectiveness of the chemical admixtures on the rheological properties of the Portland cement pastes, comparing it with a control composition of the Portland cement paste. Diagrams demonstrate changes in viscosity of the Portland cement pastes depending on the type and amount of the chemical admixtures. Obtained results were compared with the same consistence paste without admixtures. We created a new methodology of... [to full text]