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Gel Structure (gel + structure)
Selected AbstractsInteractions of ,-carrageenan Plus Other Hydrocolloids in Fish Myosystem GelsJOURNAL OF FOOD SCIENCE, Issue 6 2001M. Pérez-Mateos ABSTRACT: Mixtures of ,-carrageenan plus other hydrocolloids (locust bean, guar, xanthan, iota-carrageenan, sodium carboxymethylcellulose, and sodium alginate) were examined for their effects on the mechanical and water holding properties of heat-induced gels made from washed blue whiting mince. Gel structure and thermal behavior were also studied. No synergistic effect was detectable through functional properties except for the mixture of ,-carrageenan with locust bean gum. Light microscopy revealed that ,-carrageenan and xanthan mixed locally with locust bean at its rich domains. ,-carrageenan and xanthan presented interactions with the protein matrix, which were more discernible in the first case. Differential scanning calorimetry (DSC) revealed faint interactions for the mixtures of ,-carrageenan with locust bean and with xanthan, and weakly synergistic gelling effects between the last two hydrocolloids. The blend of ,-carrageenan with sodium alginate exhibited thermally strong synergistic interactions but no particular effects were induced on corresponding functional properties. [source] Starch-lipid composites in plain set yogurtINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2009Mukti Singh Summary Starch-lipid composites (SLC) were used to replace milk solids in yogurt mixes. The effects of the SLC on the yogurt fermentations and rheology were studied. The rate of fermentation was evaluated by the change of pH during the fermentation of yogurt. The syneresis of yogurt was observed over 3 weeks of storage. Small amplitude oscillatory shear flow measurements of the storage modulus, the loss modulus, and the loss tangent were obtained using a vane geometry. Yogurt mixes with milk solids partially replaced by SLC fermented at a similar rate than as with no milk solids replaced. Initial viscosity was higher for yogurt mixes with higher levels of SLC. The higher initial viscosity did not affect the gel structure. The addition of SLC above a level of 3% strengthened the gel and resulted in no syneresis for yogurt samples stored for 3 weeks at 4 °C. [source] RHEOLOGICAL PROPERTIES, WHEY SEPARATION, AND MICROSTRUCTURE IN SET-STYLE YOGURT: EFFECTS OF HEATING TEMPERATURE AND INCUBATION TEMPERATUREJOURNAL OF TEXTURE STUDIES, Issue 5-6 2003WON-JAE LEE The effects of heat treatment and incubation temperature on the rheological and microstructural properties of yogurt were studied. A central composite experimental design and response surface methodology were used for data analysis. The rheological properties were determined by dynamic low amplitude oscillation and the amount of spontaneous whey separation was quantified by the volumetric flask test. Confocal scanning laser microscopy was used to examine the gel structure. The storage moduli of yogurts increased with an increase in heating temperature and a decrease in incubation temperature. The maximum loss tangent value during gelation, permeability, and amount of spontaneous whey separation of yogurts increased with a decrease in heating temperature and with an increase in incubation temperature. These parameters indicated an increased possibility for rearrangements, which was confirmed by presence of large pores in the gel network. Second order polynomial models successfully predicted the effects of heating temperature and incubation temperature on the rheological properties, permeability, and whey separation of yogurts. Whey separation was negatively correlated with storage modulus (r= -0.66), and was positively correlated with the maximum loss tangent (r= 0.63) and permeability (r= 0.78). This study demonstrates that weak yogurt gels, which have high loss tangent values, favor rearrangements in the network and the resulting network has larger pores (high permeability) and exhibits greater whey separation. [source] Increased plasma fibrin gel porosity in patients with Type I diabetes during continuous subcutaneous insulin infusionJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 6 2003G. Jörneskog Summary.,Background:,Patients with Type 1 diabetes have a tighter plasma fibrin gel structure, to which impaired glycemic control might contribute. Improved glycemic control can be achieved with continuous subcutaneous insulin infusion (CSII). Objectives:,The aim of the present study was to investigate the effect of CSII on plasma fibrin gel properties and circulating markers of inflammatory activity in patients with Type 1 diabetes. Patients and methods:,Twenty-eight patients were investigated before and after 4,6 months' treatment with CSII. Fibrin gel structure formed in vitro from plasma samples was investigated by liquid permeation of hydrated fibrin gel networks. P-fibrinogen was analyzed by a syneresis method. Comparisons were made between patients with improved (> 0.5%) and unchanged (< 0.5%) glucosylated hemoglobin (HbA1c) during CSII. Results:,Eighteen patients showed improved and 10 patients unchanged HbA1c during CSII. P-fibrinogen, high sensitive C-reactive protein and serum amyloid A-antigen were not significantly changed, while fibrin gel permeability (Ks) and fiber mass,length ratio (µ) increased in both groups (P < 0.02). P-insulin and triglycerides decreased (P < 0.05) in both groups, while reductions of total cholesterol and intercellular adhesion molecule-1 were seen only in patients with improved HbA1c (P < 0.05). Absolute changes in Ks were inversely correlated to changes in plasma fibrinogen (r = 0.50; P < 0.01) and in LDL-cholesterol (r = 0.46; P < 0.05). Conclusions:,Treatment with CSII in patients with Type 1 diabetes is associated with increased plasma fibrin gel porosity. Slight attenuation of the inflammatory activity was also observed. The changes in fibrin gel porosity seem to be mainly mediated by changes in plasma fibrinogen and blood lipids, and are probably secondary to improved insulin sensitivity. [source] Radiation and postirradiation crosslinking and structure of two unsaturated polyester resinsPOLYMER ENGINEERING & SCIENCE, Issue 9 2008Irina Puci Radiation and postirradiation crosslinking of two unsaturated polyester (UP) resins were monitored, and substantial differences in the reaction course and extents were observed. DSC thermograms of one of the resins showed double peaks and significantly lower residual reaction heats. Extraction revealed that gelation dose of the resin with double peak was twice the gelation dose of the other resin that had single peak in DSC thermograms. Although other components of the polyesters were identical, NMR spectra of the resin with a single peak revealed isophthalic units while in the polyester of the resin having double DSC peaks orthophthalic units were detected. Orthophthalate reduced the compatibility of polyester and styrene and caused the reaction-induced phase separation, influencing gel structure that was visible in scanning electron microscope micrographs. Previously, the double peaks in crosslinking thermograms of UP resins were usually attributed to initiator effects, but here no initiator was used, and, in the literature, we found that the double peaks are almost exclusively present in the thermograms of UP resins containing orthophthalates, whereas in resins with isophthalates double peaks almost never appear. Crosslinking extents were significantly higher in the resin-containing isophthalate and in both cases enhanced by postirradiation reaction that is often neglected. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Spongy Polyethersulfone Membrane for Hepatocyte Cultivation: Studies on Human Hepatoma C3A CellsARTIFICIAL ORGANS, Issue 9 2008Andrzej Kinasiewicz Abstract:, There are different types of membranes used for hepatocyte cultivation. In our studies, spongy polyethersulfone (PES) membranes were examined as a support for hepatic cell cultivation in vitro. The extended surface of the membranes allows to introduce a high cell number especially in three-dimensional gel structure. Scanning electron microscopy analysis indicated that C3A cells used in our experiments grew well on PES membranes forming microvilli characteristic for normal hepatocytes. Analysis of cell viability proved that spongy PES membrane is well tolerated by J774 macrophages and did not stimulate nitric oxide synthesis. Bile canalicular structures were observed in fluorescence microscopy after F-actin staining with tetramethyl rhodamine iso-thiocyanate (TRITC)-phalloidin. The C3A cells showed high affinity to the PES membranes and adhered to almost 90% during the initial 24 h of incubation. Albumin production increased during static culture from the value of 805.2 ± 284.4 (ng/24 h/initial 106 cells) during the first days, to 2017.6 ± 505.9 (ng/24 h/initial 106 cells) after 10 days of culture. In conclusion, the spongy PES membranes can be used as scaffold for hepatocyte cultivation, especially for the creation of three-dimensional environments. [source] Cell-free synthesis of functional proteins using transcription/translation machinery entrapped in silica sol,gel matrixBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Kyeong-Ohn Kim Abstract Herewith we report the encapsulation of functional protein synthesis machinery in a silica sol,gel matrix. When the sol,gel reaction using alkoxysilane monomers was carried out in the presence of Escherichia coli cell extract, macromolecular protein synthesis machinery in the cell extract was successfully immobilized within a silica gel matrix, catalyzing the translation of co-immobilized DNA when supplied with small-molecular-weight substrates for protein synthesis. The efficiency of protein synthesis was affected by the pore size of the gel structure, which was controlled through the use of appropriate additives during the sol,gel reactions. To the best of our knowledge, this is the first report describing the reproduction of the entire set of complicated biological process within an inorganic gel matrix, and we expect that the developed technology will find many applications in numerous fields such as high-throughput gene expression and the development of multifunctional biosensors. Biotechnol. Bioeng. 2009;102: 303,307. © 2008 Wiley Periodicals, Inc. [source] Temperature Dependence of Sol-Gel Conversion Kinetics in Gelatin-Water SystemMACROMOLECULAR BIOSCIENCE, Issue 4 2009Kai Chen Abstract The conversion kinetics of an aqueous gelatin solution to gel was studied by temperature modulated and regular DSC under isothermal and continuous cooling conditions. Isothermal runs revealed a decrease in the quasi-static heat capacity primarily associated with syneresis (phase separation) of the gel. Above 19,°C the isothermal process demonstrated negative effective activation energy that turned positive below 14,°C. Continuous cooling runs detected a reversing heat flow apparently related to the continuing formation and melting of new gel structures. Isoconversional kinetic analysis of continuous cooling measurements yielded negative activation energy for the whole range of conversions and temperatures suggesting that nucleation remained a rate controlling step throughout the whole gelation process. [source] | ||||||||||||||||