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51.
Ozan Tas Ulku Ertugrul Mecit Halil Oztop Bekir Gokcen Mazi 《International Journal of Food Science & Technology》2021,56(11):5461-5470
Modification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d -Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier-transform infrared spectroscopy analysis, antioxidant activity experiments and time-domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d -Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities. 相似文献
52.
Jin‐Hong Zhao Rui Hu Hong‐Wei Xiao Yang Yang Fang Liu Zhi‐Lin Gan Yuan‐Ying Ni 《International Journal of Food Science & Technology》2014,49(4):960-968
The effect of osmotic dehydration pretreatment on the quality attributes (e.g. colour, hardness, drip loss, vitamin C content and pH) of frozen mango cuboids in different osmotic solutions (sucrose, glucose and maltose) and concentrations (30, 45 and 60% (wt/wt)) was investigated. Results revealed that melting temperature of mango cuboids was affected by both solute type and solid mass fraction. In addition, the dehydrofrozen samples pretreated in maltose had higher quality in vitamin C content (increasing by 23.5–73.0%), colour (colour change reducing by 2.6–39.2%) and drip loss (reducing by 0.7–9.7%) than those pretreated in other osmotic solutions. The cuboids pretreated in glucose displayed higher hardness (increasing by 16.4–36.2%). Based on principal component analysis and group distance, osmotic dehydration in 45% maltose was proposed as the most favourable freezing conditions with the highest sensory score (6.8). The current work indicates osmotic dehydration significantly improves frozen mango quality. 相似文献
53.
The hurdle effect of osmotic pretreatment and high‐pressure cold pasteurisation on the shelf‐life extension of fresh‐cut tomatoes
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Efimia K. Dermesonlouoglou Varvara Andreou Zacharias Alexandrakis George J. Katsaros Maria C. Giannakourou Petros S. Taoukis 《International Journal of Food Science & Technology》2017,52(4):916-926
Tomatoes are perishable products due to the activity of microorganisms and endogenous enzymes. The objective was to produce cut tomatoes with extended shelf life, using the combined hurdle effect of osmotic pretreatment (OD) and high pressure (HP), instead of a conventional one‐step thermal process. Samples were processed in a multicomponent osmotic solution at 35 °C, subsequently cold‐pasteurised in pack at 600 MPa and stored at 5–15 °C. Quality deterioration during isothermal and nonisothermal storage was kinetically modelled. Both OD process and OD‐HP combined process caused an increase in lycopene content that was well retained. Texture, colour and flavour of treated samples were evaluated as similar to fresh, with OD‐HP samples showing better retention during storage. Being microbiologically stable, shelf life of OD‐HP samples was limited by sensory deterioration, whereas OD samples were rejected due to eventual microbial growth. Shelf life of OD and OD‐HP samples was estimated at 77 and 181 days, respectively, at 5 °C. 相似文献
54.
M.A. Armenta R. Valdez J.M. Quintana R. Silva-Rodrigo L. Cota A. Olivas 《International Journal of Hydrogen Energy》2018,43(13):6551-6560
A recent alternative for replacing traditional hydrocarbons like gasoline, diesel, and natural gas, is the use of dimethyl ether (DME), which is more environmentally friendly. One of the ongoing challenges is to catalyze methanol dehydration for selectively producing the DME (2CH3OH → CH3OCH3 + H2O). It is established that the CuO catalyst over alumina performs the methanol dehydration, but the formation of by-products is the main drawback. For these reasons, we synthesized a CuO/γ–Al2O3 catalyst promoted with hematite aiming to enhance the activity toward DME at atmospheric conditions. The resulting bimetallic catalyst (CuO-Fe2O3/Al2O3) performed a 70% conversion at 290 °C, which is similar to other catalysts recently reported in the literature but done in harsh conditions. In addition, this bimetallic catalyst exhibited a 100% in selectivity toward the DME production. XPS spectra of the fresh and used catalyst suggested that the chemical oxidation states of Cu and Fe remain without change. After regenerating the catalyst at 600 °C for 2 h in air, it performed at a similar catalytic conversion, confirming the reusability of the as-synthesized material and reducing the environmental impact. 相似文献
55.
BACKGROUND: Water‐plasticized poly(vinyl alcohol) has been obtained by thermal processing. Dehydration is the key process for controlling the structure and performance of the water‐soluble polymer, and mass transfer is an important part of dehydration. RESULTS: A simple new model of a hyperbolic‐type function was developed to understand the mass transfer process of water‐plasticized poly(vinyl alcohol) systems during isothermal dehydration. The model was verified by statistical tests. The physical parameters in the model were defined as the maximum weight loss fraction and characteristic time. The dehydration rate, the key physical parameter in mass transfer, was obtained from the differential equation of the model. By use of the model, the characteristics of dehydration of poly(vinyl alcohol) were determined: the complete mass transfer process can be divided into a fast mass transfer before a characteristic time (τ) and a slow mass transfer after τ, and dehydration temperatures can also be divided into two intervals by different activation energies. In addition, the dehydration rate is inversely proportional to the degree of crystallinity. CONCLUSION: The results of the new model agree reasonably well with experimental results obtained by thermogravimetry and weighing. Poly(vinyl alcohol), as a water‐soluble semicrystalline polymer, exhibits a particular mass transfer behavior during dehydration. Copyright © 2008 Society of Chemical Industry 相似文献
56.
Subjected to the wet surrounding, hydrated cement paste (HCP) exposed to high temperature may exhibit rehydration behavior. This paper presents the influence of the dehydration temperature and the initial water/cement ratio on the rehydration activity of dehydrated cement paste (DCP). Original HCPs were prepared with two water/cement ratios of 0.3 and 0.5, respectively, and cured under the fog‐spraying standard condition for 30thinspacedays. The DCP powders used were obtained by grinding dry HCP less than 75µm and then subjecting to different temperatures, up to 900°C. The rehydration properties of DCP were evaluated by the required water for standard consistency, the setting time, the rehydrated compressive strength and the microstructure evolution. X‐ray diffraction (XRD) was employed to identify the crystalline phases before and after rehydration. Experimental results showed that the coupled rehydration effect from the dehydrated hydration products and the initially unhydrated cement determined the rehydration behavior of DCP. The rehydration of DCP strongly depended on the dehydration temperature and the water/cement ratio of the original HCP. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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59.
Kamilla Soares de Mendonça João Renato de Jesus Junqueira Michel Cardoso de Angelis Pereira Marina Barbosa Vilela 《Drying Technology》2016,34(4):386-394
Osmotic dehydration assisted by ultrasound (ODAU) at low temperatures reduces water activity (aw) and maintains nutrients. The influence of solution concentration (SC; 20 to 60° Brix, xylitol and sorbitol) and ultrasound application time (tus, 0 to 40 min) in ODAU of yacon was studied with the aid of a response surface method. The optimum condition with respect to mass transfer parameters, aw, and fructan retention was SC of 60° Brix for both solutions and tus of 2.67 min for xylitol samples and 0 min for sorbitol samples. The application of ultrasound improved dehydration but resulted in depolymerization of fructans. 相似文献
60.
Teflon AF2400/Ultem composite hollow fiber membranes for alcohol dehydration by high‐temperature vapor permeation
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Dan Hua Tai‐Shung Chung Gui Min Shi Chao Fang 《American Institute of Chemical Engineers》2016,62(5):1747-1757
High‐temperature vapor permeation has a stringent requirement of membrane stability under harsh feed environments. This work reports the design of Teflon AF2400/Ultem composite hollow fiber (HF) membranes for alcohol dehydration via vapor permeation. Fabrication parameters such as Teflon concentration and coating time were systematically investigated. Interestingly, the fabricated composite HF membranes possess an unusual surface with honeycomb‐like microstructure patterns. Owing to the Teflon protective layer, the newly developed composite HF shows a promising and stable separation performance with a flux of 4265 gm?2 h?1 and a separation factor of 383 for 95% isopropanol dehydration at 125°C. The composite HF also performs well under extreme vapor feed compositions from 87 to 99 wt % isopropanol. In addition, it exhibits impressive separation performance for the dehydration of ethanol and n‐butanol. This work may provide useful insights of designing thermal‐stable and high‐performance composite polymeric membranes for vapor permeation. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1747–1757, 2016 相似文献