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Fodder palm, a great source of nutrients for human and animals, grows even in arid climates. Pulsed vacuum osmotic dehydration is an efficient process for obtaining semidehydrated food. It was used to slice cladodes of fodder palm...
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Fodder palm, a great source of nutrients for human and animals, grows even in arid climates. Pulsed vacuum osmotic dehydration is an efficient process for obtaining semidehydrated food. It was used to slice cladodes of fodder palm. The independent variables used were temperature (30-50℃), pulsed vacuum pressure (50-150 mbar) and NaCl concentration (5-15 g per 100 g solution). The response variables were water activity (a_w), moisture content (X), colour parameters, water loss (WL), solid gain (SG) and weight reduction (WR). The pulsed vacuum osmotic dehydration process was optimised for minimum values of a_w, X and SG, and maximum values of chroma. The experimental data obtained with the optimum condition (100 mbar; 10 gNaCl per 100 g solution, 44℃) were near the estimated ones. For example, WL, a_w and △E, and their error were 8.15 g per 100 g, 11%; 0.985, 0.3% and 6.15, 15.2%, respectively.
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The pulsed vacuum osmotic dehydration (PVOD) promotes more homogeneous concentration profiles in the product and quality improvement of several fruits. The objective of this work was to study the drying of plums submitted to treat...
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The pulsed vacuum osmotic dehydration (PVOD) promotes more homogeneous concentration profiles in the product and quality improvement of several fruits. The objective of this work was to study the drying of plums submitted to treatments of plants manure with KCI and PVOD (5" c.a., 10 min). Experimental planning was done with the following independent variables: doses of KCI (400, 700 and 1000 g/plant), concentration of sucrose solution (40; 50 and 60 °Brix) and drying temperature (50, 60 and 70C). The tested variables were: color, shrinkage, visual quality and rehydration. Temperature leads to a skin browning at fruit pulps and lower visual quality. The treatment with KCI leads to final products with lower moisture content. The higher the values of all the independent variables, the lower the shrinkage and the rehydration capacity. Plums submitted to convective drying with previous PVOD promote a new product with good visual quality and satisfactory shrinkage.
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A novel variant of osmotic dehydration, named here as postdipping dehydration-where a material is dipped in a salt or sugar solution for a very short time followed by simple exposure to ambient conditions was explored with the aim...
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A novel variant of osmotic dehydration, named here as postdipping dehydration-where a material is dipped in a salt or sugar solution for a very short time followed by simple exposure to ambient conditions was explored with the aim of lowering water content of potato slices but at the same time not gain a high level of sugar/salt. The rate of water loss, which was rapid initially, was found to approach equilibrium. This article also explored whether the water loss process could subsequently be kick started once again, by employing a multistage process, where each stage consisted of osmotic solution dipping followed by ambient holding of the potato slices that had reached equilibrium in the earlier stage. Water loss values comparable to conventional osmotic dehydration could be achieved thus, but with significantly lower overall solid gain (<50%)-which can potentially yield a significantly healthy product option.
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Powders of donepezil hydrochloride monohydrate (Form Ⅰ) underwent isomorphic dehydration, losing 3% w/w water between 90% and 10% relative humidity (RH) without changing its powder X-ray pattern. Below 10% RH, additional dehydrat...
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Powders of donepezil hydrochloride monohydrate (Form Ⅰ) underwent isomorphic dehydration, losing 3% w/w water between 90% and 10% relative humidity (RH) without changing its powder X-ray pattern. Below 10% RH, additional dehydration occurred in conjunction with a reversible phase transition between the monohydrate state and a dehydrated state, with a 4.0% w/w loss to 0% RH. A combination of methods was used to understand the structural changes occurring during the desolvation process, including dynamic vapor sorption measurements, thermal analysis and powder X-ray diffraction. Form Ⅰ showed the characteristics of the channel hydrate, whose non-isothermal dehydration behavior proceeds in two steps: (1) the loss of non-crystalline water adsorbed on the surface, and (2) the loss of one crystalline water in the channel. Dehydrated Form Ⅰ is structurally similar to the monohydrate Form Ⅰ. According to the heat of fusion and the crystal density criteria, the two crystal forms belonged to the univariant system, and the anhydrate (Form Ⅲ) is stable. The dehydration kinetics was achieved from the TG-DTG curves by both the Achar method and the Coats-Redfern method with 15 frequently cited basic kinetic models. The dynamic dehydration processes for steps 1 and 2 were best expressed by the Zhuralev-Lesokin-Tempelman equation, suggesting a three-dimensional diffusion-controlled mechanism.
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Thermal decomposition of thorium oxalate hexahydrate was investigated under nonisothermal and isothermal conditions in moist argon by using simultaneous thermogravimetric-differential thermal analyser. Nonisothermal experiments we...
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Thermal decomposition of thorium oxalate hexahydrate was investigated under nonisothermal and isothermal conditions in moist argon by using simultaneous thermogravimetric-differential thermal analyser. Nonisothermal experiments were carried out at various linear heating rates. Intermediates formed in each stage of the thermal decomposition of thorium oxalate hexahydrate were deduced. Kinetics of decomposition in each stage were evaluated from the dynamic TGA-DTA data by means of Coats and Redfern equation. The values of the activation energy (E) and the pre-exponential factor (A) of each stage of the thermal decomposition at various linear heating rates were calculated. These kinetic parameters were evaluated from isothermal experiments also and probable decomposition mechanism is proposed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 13]
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The adsorption characteristics are studied for nano- and ultraporous glasses (PGs) produced from sodium borosilicate glasses and a glass containing small amounts of fluoride ions and phosphorus oxide by acid (HCl) leaching and add...
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The adsorption characteristics are studied for nano- and ultraporous glasses (PGs) produced from sodium borosilicate glasses and a glass containing small amounts of fluoride ions and phosphorus oxide by acid (HCl) leaching and additional alkaline (KOH) and thermal treatment. The surface charges sigma(0) of PGs are determined by continuous potentiometric titration in 10(-3)-1 M NaCl, KCl, and (C2H5)(4)NCl solutions. Only negative surface charges of PGs are observed for all investigated systems. The |sigma(0)| value is predetermined by the following factors: the composition of PG, the pore radius in the nanometer region (r 13 nm), the surface charge is almost independent of the pore radius.
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The crystal structure of synthetic Rb-2[B4O5(OH)(4)]. 3.6H(2)O has been established from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic space group Pbcn with a unit cell of dimensions a = 11.276(5) Angs...
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The crystal structure of synthetic Rb-2[B4O5(OH)(4)]. 3.6H(2)O has been established from single-crystal X-ray diffraction data. It crystallizes in the orthorhombic space group Pbcn with a unit cell of dimensions a = 11.276(5) Angstrom, b = 13.097(14) Angstrom, c = 16.751(5) Angstrom; V = 2474(3) Angstrom(3); Z = 8, The structure was determined from 1201 independent reflections and refined until R = 0.049 and R-w = 0.036; it is composed of isolated [B4O5(OH)(4)](2-) polyanions separated by free water molecules and Rb+ ions, Some of the positions of rubidium and oxygen atoms-the latter are attributed to water molecules-were localized with occupancy factors of 0.5 and 0.3. A similarity appears with the unit cell parameters of Cs-2[B4O5(OH)(4)]. 3H(2)O: a = 8.424 Angstrom, b = 11.378 Angstrom, c = 13.160 Angstrom, beta = 92.06 degrees; V = 1260.5 Angstrom(3); Z = 4; space group P2(1)/c; in fact, the unit cell volume of rubidium berate is doubled but the symmetries of these two compounds are quite different. However, they contain identical [B4O5(OH)(4)](2-) polyanions, The dehydration of Rb-2[B4O5(OH)(4)]. 3.6H(2)O consists of a continuous loss of water until 300 degrees C, forming anhydrous Rb2B4O7, which is amorphous to X-ray diffraction, Rb2B4O7 crystallizes at about 475 degrees C and melts at 717 degrees C. Two forms of Rb2B4O7 appear on the temperature resolved X-ray powder diffraction pattern. One corresponds to the triclinic form of the structure which has been solved recently; to this day, the other one has not been isolated. (C) 2000 Academic Press. [References: 24]
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Although it has been suggested that many in the general population are dehydrated to the extent that mood and cognition are disrupted, there has been little research investigating mild levels of dehydration. When dehydration reduc...
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Although it has been suggested that many in the general population are dehydrated to the extent that mood and cognition are disrupted, there has been little research investigating mild levels of dehydration. When dehydration reduces body mass by more than 2%, it has been consistently reported that mood is influenced, fatigue is greater, and alertness is lower. In contrast, the effects on cognition have been less consistent. Only a few studies have looked at females and these studies made little attempt to consider hormones that influence kidney functioning. In particular, there has been virtually no attempt to look at changes in hydration status in the range that occurs in individuals with a sedentary lifestyle in a temperate climate. There is a consequent need to study individuals who have lost up to 1% of body mass due to dehydration. While 4 intervention trials have found that the cognition of children improved in response to water consumption, the effects of water consumption on cognition in older adults, another high-risk group, have been largely ignored.
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Fried glutinous rice cracker is a popular snack for local Thais. One of the production steps usually requires drying.? Method of drying is an important process affecting products, shelf life and quality. In this research study, qu...
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Fried glutinous rice cracker is a popular snack for local Thais. One of the production steps usually requires drying.? Method of drying is an important process affecting products, shelf life and quality. In this research study, quality of rice cracker obtained from various drying methods (direct solar radiation, solar dome, and hot air drying oven) was investigated and compared. Properties of the rice cracker being analyzed were shrinkage ratio, expansion ratio, color, hardness and crispness. The rice cracker samples were in rectangular slap. Experimental results showed that the final moisture content of the rice cracker was in the range of about 8-10% wet basis. Direct solar drying gave minimum shrinkage ratio of 1.34 and maximum expansion ratio of 4.99. The color of dried rice cracker was given as L* a* b* color space. The highest hardness of the rice cracker (2,200 g) can be reached by hot air drying, and the best crispness (18,000 g.s) was obtained by direct solar drying.
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Design and control of an extractive distillation system for tetrahydrofliran (THF) dehydration with ethylene glycol as entrainer is investigated. The main module is a two-column system containing an extractive distillation column,...
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Design and control of an extractive distillation system for tetrahydrofliran (THF) dehydration with ethylene glycol as entrainer is investigated. The main module is a two-column system containing an extractive distillation column, whose top stream is the desired product THF, and an entrainer recovery column. Economic analysis with total annual cost as the objective function is developed. Two kinds of control strategies are explored for THF dehydration. The responses reveal that the control structure with fixed reflux ratio cannot maintain the bottom liquid level of the entrainer recovery column, while the control scheme with fixed reboi-ler heat duty/feed flow ratio exhibits good control performance in spite of large deviations in feed flow rate and feed composition.
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