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Temperature Effect on the viscosity of Commercial Carrot Puree

Journal of Food Science and Engineering 2017年第10期7卷 505-513页

作者： Vimes-Delgadillo Jorge-Octavio, Dominguez-Rendón Ana-Cristina López-del-Castillo-Lozano Micloth Dominguez-Cafiedo Irma-Liliana Galán-Méndez Frixia Facultad de Ciencias Quimicas Universidad Veracruzana Lomas del Estadio S/N Xalapa Veracruz 91000 México

Temperature effect was evaluated over the viscosity of commercial carrot puree in the range 30 to 60 ℃, using aBrookfield viscometer, model 4535, Lab-Line instruments. In order to perform the viscosity tests, 28 specimens of carrot puree froma local market were used. Totally, 72 tests （each one with a couple replicas） were performed during five minutes, using fourtemperatures （30, 40, 50 and 60 ℃）, six shear rates （0.26, 0.52, 1.05, 2.09, 5.24 and 10.47 s1） and three spindles （4, 5 and 6）.Statistical analysis was performed using LSD and Duncan tests with a confidence interval of 95% （p value of 0.05）. In the currentstudy, it was observed that an increase in the temperature triggers a reduction in the viscosity of the carrot specimens analyzed,although the samples tested at 60℃ were deviated from this trend, which may be due to denaturation of the starch containing carrotsamples at such temperature. Multiple biochemical and micro-structural changes inside the food specimens may begin to occur belowand over the physiological range （20-45 ℃）. Experimental data were analyzed with Power Law model in order to obtain the bestfitted parameters as a function of shear rate： It was observed that the consistent index （k） decreased with an increment in thetemperature; while all the values of parameter ＂n＂ lesser than one, which means that the puree samples behaved as a pseudo-plasticfluid. Besides that, an Arrhenius model was used to fit the parameters as a function of temperature： Parameter A was lower usingtheexperimental data at shear rates of 10.47 s-1. The modeling performed may be helpful for the appropriate selection of some processvariables, as the shear rate and operation temperature, used for the production of carrot puree; all this is in order to obtain the finishedproduct with the desired consistency.

关键词： Food rheology, viscosity, temperature, carrot puree.

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Shear Rate Effect on the viscosity of Homemade and Commercial Tomato Sauce

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Journal of Food Science and Engineering 2017年第10期7卷 479-496页

作者： Virues-Delgadillo Jorge-Octavio Lozada-Santillan Claudia-Karina Bulbarela-Sampieri Carmen Galán-Méndez Frixia López-del-Castillo-Lozano Micloth Facultad de Ciencias Quimicas Universidad Veracruzana Lomas del Estadio S/N Xalapa Veracruz 91000 México

Rheological characterization of tomato products is important not only for design of unit operations, but also to optimizeprocesses and guarantee high quality of food products. Time dependence is related with structural changes due to shear rate. Thus,rheological characterization as a function of time is extremely important to understand the changes that occurred in food productsduring commercial processes. However, these characterizations are rare in the literature for tomato products. Those rheologicalproperties depend of several parameters, such as agronomic, structural and process parameters. In this study, the effect of shear rateon the viscosity at room temperature （22 ~C） of two kinds of tomato sauce （homemade and commercial） is analyzed; using aBrookfield viscometer model 4535, Lab-Line Instruments. Homemade sauce was prepared with fresh saladette tomatoes from a localmarket. Rheological analysis was performed at shear rates from 0.05 to 10.47 sl; using all the spindles available. Statistical analysiswas made using LSD and Duncan tests with a confidence interval of 95% （p-value of 0.05）. It was demonstrated that homemade andcommercial tomato sauce behaved as a thixotropic fluid, due to the typical decrease on viscosity samples observed when testing timewas increased. When tomato sauce is at rest, it has a gelled tridimensional structure; and, as soon as a shear stress is applied, themovement generates an alignment of tomato constituent chains in flow direction, breaking physic entanglements and thus causing adecrease in viscosity as a function of time. Furthermore, it was discovered that the viscosity of homemade sauce was higher than theviscosity of commercial sauce. The latter may be due to the pre-thermal treatment. During this unit operation, polymeric chains oflycopene most likely break into smaller chains of isoprene, causing the observed decrease in viscosity. Besides, commercial saucecontains additives, seasonings, preservatives and thickeners that ar

关键词： Food rheology, viscosity, shear rate, tomato sauce.

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Piezoelectric resonators with mechanical damping and resistance in current conduction

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Science China(Physics,Mechanics & Astronomy) 2007年第5期50卷 650-672页

作者： Yook-Kong YONG Mihir S PATEL Department of Civil and Environmental Engineering Rutgers University Piscataway NJ 08854 USA

A novel design method for high Q piezoelectric resonators was presented and proposed using the 3-D equations of linear piezoelectricity with quasi-electrostatic approximation which include losses attributed to mechanical damping in solid and resistance in current conduction. There is currently no finite element software for estimating the Q of a resonator without apriori assumptions of the resonator im- pedance or damping. There is a necessity for better and more realistic modeling of resonators and filters due to miniaturization and the rapid advances in frequency ranges in telecommunication. We presented new three-dimensional finite element models of quartz and barium titanate resonators with mechanical damping and resistance in current conduction. Lee, Liu and Ballato’s 3-D equations of linear piezoelectricity with quasi-electro- static approximation which include losses attributed to mechanical damping in solid and resistance in current conduction were formulated in a weak form and implemented in COMSOL. The resulting finite element model could predict the Q and other electrical parameters for any piezoelectric resonator without apriori as- sumptions of damping or resistance. Forced and free vibration analyses were per- formed and the results for the Q and other electrical parameters were obtained. Comparisons of the Q and other electrical parameters obtained from the free vibra- tion analysis with their corresponding values from the forced vibration analysis were found to be in excellent agreement. Hence, the frequency spectra obtained from the free vibration analysis could be used for designing high Q resonators. Results for quartz thickness shear AT-cut and SC-cut resonators and thickness stretch poled barium titanate resonators were presented. An unexpected benefit of the model was the prediction of resonator Q with energy losses via the mounting supports.

关键词： quality factor, energy sink, MEMS, mechanical dissipation and viscosity, electrical conductivity, piezoelectric materials

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Models to estimate viscosities of ternary metallic melts and their comparisons

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Science China Chemistry 2003年第3期46卷 280-289页

作者： WANG Xidong (王习东) LI Wenchao (李文超) Department of Physical Chemistry University of Science and Technology Beijing Beijing 100083 China Department of Physical Chemistry University of Science and Technology Beijing Beijing 100083 China

Three models, based on Chou's general geometric thermodynamic model, to predict the viscosity of ternary metallic melts have been established. The calculation equations of the model have been deduced. The experimental viscosity data of Ag-Au-Cu systems were used to verify the models and the calculation results with the models are consistent with the reported experimental data. The advantages, requirement and applicability of the models have been analyzed and compared. The models have also been utilized to predict the viscosity of Ag-Sn-Cu system. The viscosity of the system was experimentally measured and the results are consistent with the calculated value of the models.

关键词： viscosity, geometric model, estimation, metallic melts.

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Development of improving processing HNBR

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合成化学 2004年第Z1期12卷 112-112页

作者： LI Jin-shan HU Hai-hua Petrochemical Research Institute of Lanzhou Petrochemical Company Lanzhou 730060China Petrochemical Research Institute of Lanzhou Petrochemical Company Lanzhou 730060China

The hydrogenated nitrile elastomer (HNBR) is a new rubber consisting of methylene chain, cyano groups and a small number of C=C. This elastomer is produced by selection hydrogenation reaction of the olefin segments in NBR. During reaction, only the double bond should be selectively hydrogenated without the cynao groups which are essential for retaining the oil resistant properties of NBR. Present, the capacity of HNBR in total world is about 7500t/a[1],developed and commercialized by Bayer (Germany)and Zeon (Japan),trademark is THERBAN and ZETPOL respectively. In domestic, We (Lanzhou Petrochemical Company) has built a 100t/a HNBR pilot *** known, Mooney viscosity is a key factor in rubber processing, low Mooney viscosity will result in decreasing of strength, increasing of compression set, whereas high Mooney viscosity is hard to process, also must be plasticated. In order to overcome above problems, we designate and synthesize a base rubber as NBR-1 by modifying molecular weight distribution(MWD),its MWD is more than conventional NBR as NBR-2,correspondently their Mw, Mn and MWD are 14.9,2.2,6.78 and 13.9,4.3,*** hydrogenated product are quoted as HNBR-1 and *** polymer Mooney viscosity (ML1+4 100℃) are 39 and 82.A solution of 3.5kg of NBR-1 containing 36% by weight of acrylonitrile,in 35kg of chlorobenzene and a solution of 5.5g of tris-(triphenylphosphane)-rhodium-chloride[2] in 2.5kg of chlorobenzene are introduced into a 50 liter autoclave blanketed with nitrogen. The nitrogen is replaced by hydrogen and hydrogenation is carried out for 8hr at 100℃-120℃,under a hydrogen pressure of 8 Mpa. The hydrogenation process of NBR-2 same as that of *** degrees of hydrogenation amount to ＞ 98%(as determined by iodine value).We find MWD of base NBR has a most effect on HNBR. Table 1 shows a comparison of physical properties of HNBR-1 and *** would be expected lower polymer Mooney viscosities yield lower compound Mooney *** is

关键词： Butadiene-acrylonitrile rubber, Hydrogenation, Molecular weight distribution ,Mooney viscosity, Property

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