THERMODYNAMIC ANALYSIS OF STRUCTURING PROCESS OF HYDROCOLLOID SYSTEMS OF FOOD BIOPOLYMERS

Для углубления фундаментальных представлений о механизме гелеобразования пищевых биополимеров на молекулярном уровне проведен термодинамический анализ условий и факторов, оказывающих влияние на процесс структурирования их водных растворов. На основе количественного описания параметров и оценки закономерностей структурирования при взаимодействии активных групп коллоидов с дисперсионной средой рассмотрены термодинамические особенности фазовых переходов гидроколлоидных систем. Обосновано, что энергетическое состояние таких водных систем зависит от показателя активной кислотности, определяется величиной заряда молекул, количеством реакционноспособных групп и вязкостью водных структур пищевых биополимеров. Представлен пример прогнозного расчета конформационных характеристик молекул желатина как одного из широко распространенных и типичных представителей пищевых биополимеров. Показано, что при рН 11 ед. заряд молекулы составляет минус 40 ед., а характеристическая вязкость (15,0 см3/г), гидродинамический радиус (5,24 нм) и площадь поверхности (345,0 нм2) являются наибольшими по сравнению с нейтральной и кислой средами. To deepen the fundamental understanding of the mechanism of gelation of food biopolymers at the molecular level, a thermodynamic analysis of the conditions and factors that influence the process of structuring their aqueous solutions was carried out. Thermodynamic features of phase transitions of hydrocolloid systems are considered on the basis of quantitative description of parameters and estimation of regularities of structuring in the interaction of active groups of colloids with a dispersion medium. It is shown that the energy state of such water systems depends on the active acidity index, is determined by the amount of charge of molecules, the number of reactive groups and the viscosity of water structures of food biopolymers. An example of predictive calculation of conformational characteristics of gelatin molecules as one of the most common and typical representatives of food biopolymers is presented. It is shown that at a pH of 11 units, the charge of the molecule is minus 40 units, and the characteristic viscosity (15,0 cm3/g), hydrodynamic radius (5,24 nm), and surface area (345,0 nm2) are the largest in comparison with neutral and acidic media.

Pengaruh Suhu Pencampuran dan Lama Pengadukan terhadap Karakteristik Sediaan Krim

This research aims to determine the effect of temperature and time of stirring on a basis cream and determine the temperature and time of stir which is the best treatment for producing basis cream. This research uses a randomized block design with two factorials. The first factor is temperature which is consists of 3 levels, temperature 60±20C, 70±20C and 80±20C. The second factor is the time of stirring which is consists of 3 levels 10, 15 and 20 minutes. From the combination of the two factors, were obtained of 9 experimental units. These treatments were grouped based on the time of implementation into two groups so that 18 experimental units. The observed variables are homogeneity, viscosity, adhesion, spread ability, separation ratio and pH. The data that obtained will be analyzed by analysis of variance and continued using the Tukey test. The treatment of mixing temperature and time of stirring affect the viscosity, adhesion, dispersion and separation ratio, while the treatment of mixing temperature and time of stirring did not significant effect on pH. The interaction between the two treatments can affects the adhesion, dispersion, separation ratio and pH, but not significantly affect viscosity. The treatment of mixing temperature 80±20C with time of stirring 20 minutes is the best treatment to produce basis cream with characteristic viscosity cream value of 46,000 cp, a adhesion time of 17.97 seconds, spread ability of 6.50 cm, a separation ratio of 0.83 and pH 6,45. Keywords: Mixing temperature, stirring time, cream characteristics, virgin coconut oil, cocoa butter.

STUDY OF DILUTED SOLUTIONS OF PORPHYRIN-CONTAINING POLYMERIC SYSTEMS BASED ON POLY-4-VINYLPYRIDINE

The dynamic light scattering method was used to determine the diffusion coefficients and hydrodynamic radius of particles in diluted dimethylformamide solutions of poly-4-vinylpyridine, polystyrene, styrene and 4-vinylpyridine copolymers with different comonomer compositions and poly-4-vinylpyridine modified by zinc meso-tetraphenilporphrine. The temperature range was from 20 °C to 25 °C. The copolymers were obtained in different conditions - by thermal and microwave heating. In order to determine the optimal conditions for the behavior of macromolecular reactions involving these polymers, diluted solutions of all samples were studied by the viscometric method. For these systems, a solvent of appropriate quality was selected, the structure of the solution was studied, the interaction of the solvent with the polymer was evaluated, the parameters of the macromolecular ravel were calculated: characteristic viscosities, Huggin’s constants, root-mean-square distances between the ends of the chains and the specific indicator of the system taking into account the molecular weight of the polymers was presented. It is shown, that the values of characteristic viscosity fall with increasing temperature, the Huggin’s constant, on the contrary increases. These data indicate that the "quality" of the solvent for the systems under study is deteriorating, that is, the tangle of macromolecules in dimethylformamide shrinks with increasing temperature. This behavior is typical for systems with a lower critical temperature of dissolution. The introduction of the porphyrin fragment into the polymer macromolecule loosens the macromolecular coil, but does not change the behavior of the system in the solution as a whole. The results obtained by the quasi-elastic light scattering method are consistent with the data obtained by the viscometric method. The surface morphology and elemental composition of poly-4-vinylpyridine and coordination-related porphyrin polymers on its basis were studied by scanning electron microscopy.

An Investigation of Injection Times Affect on Properties of Recycled Glass Fiber Reinforced Flame Retardant PBT

Due to its excellent comprehensive properties, glass fiber reinforced flame retardant PBT was widely applied in electrical accessory. In this paper, the recycled glass fiber reinforced flame retardant PBT（RGFFRPBT）with injection times effect on its carboxyl content, characteristic viscosity of PBT and the average length of glass fiber were studied. The properties of RGFFRPBT PBT including mechanical, thermal and rheological properties were well investigated. The results demonstrated that when GFFRPBT was injected third time, the length of glass fiber and characteristic viscosity of PBT decreased from 895um, 0.95 to 590um, 0.52, respectively. It also indicated that the decrease trend would accelerate with higher injection times. When the injection times were twice, the notched impact strength, flexural and tensile strength of RGFFRPBT-2nd decreased to 54J/m, 128MPa and 96.1MPa, respectively. Thermal stability, maximal crystallization temperature, melting point and HDT of RGFFRPBT-2nd were not significant differed to those of GFFRPBT. When the injection times were higher than three times, all of the properties decreased drastically. With the increasing of injection times, the samples show shear-thinning and nonlinear viscoelastic properties and the shear viscosity decreased, distinctly. The results illuminated that mechanical and thermal properties of RGFFRPBT-2nd were suitable to use in the electronic and electric field.

Surface Tension and Viscosity of Herbal Massage Oil

Herbal oils have been used for centuries as a traditional medicine. In this study, herbal massage oil was prepared by using crocodile oil (CO) or virgin coconut oil (VCO) as carrier oil. This experiment was conducted to find out the suitable method for preparation of herbal massage oils from CO or VCO. The satisfactory appearance and viscosity of herbal massage oil was received when using 44.9% by weight of crocodile oil as carrier oil. Searching appropriate for herbal massage oil, that exhibited the good characteristic, viscosity, fragrance and hot, was done with various systems. The carrier oils heated with Zingiber montanum (Plai, ZM) (22.45 % w/w) and Curcuma sp. (Wan ma leung, CS) (22.45 % w/w) and then the mixture was mixed with butylated hydroxyl toluene (BHT), menthol, methyl salicylate and camphor were likely to be the appropriate method. The surface tension of the mixture between different herbal oils and carrier oil in the ratio of 1:1 was no significantly difference. The highest viscosity was obtained from the mixture of carrier oil and Curcuma aromatic (Wan nang kum, CA). Oil extracted from herbal with heat treatment could mask the unpleasant odor of CO and VCO but not significantly affected the surface tension and viscosity of carrier oils.