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关键词： Powder X-ray diffraction   Rietveld method   Starch modification   Crystallinity   Molecular size distribution   C-type starch  

摘要： Extracted from a tuberous root of the Amazon forest named Ari?a (Goeppertia allouia), starch samples were submitted to four ?-radiation doses of 1, 5, 20 and 50 kGy and investigated by powder X-ray diffraction (XRD) and pasting properties. The XRD patterns were quantified by the Rietveld refinement method and the pasting properties by Palabiyik?s, Hill?s and Arrhenius models. Crystallinity values were obtained considering the semicrystalline microstructures (mean crystallites sizes and microstrains) and the weight fraction of the semicrystalline phases were calculated considering the diffuse X-ray scattering. The combination of the techniques revealed that the increase in the amorphous component is related to the continuous degradation of the semicrystalline phases in lower molecular weight sugars that also increased pasting temperature and delaying the gelation process. The reduction in the activation energy of the phase transition is associated with the accumulated energy in the defects, induced by ?-radiation.

关键词： Ethanolic extracts   Takifugu obscurus   Taste characterization   NMR   Nano LC-MS   Antioxidant peptides  

摘要： Most umami substances were developed in aqueous extracts. In this study, we compared the molecular weight distributions and sensory characteristics of ethanol and aqueous Takifugu obscurus muscle extracts, and assessed their taste-related metabolites and peptide profile (< 3 kDa) using nuclear magnetic resonance and nano liquid chromatography-mass spectrometry. The potential antioxidant peptide in ethanolic fraction was screened using Peptide Ranker, BIOPEP and quantum chemical simulations. The results indicated that 60% ethanolic extract fraction (60%-F) had the highest umami intensity and more palatable overall taste among all pufferfish extracts. It can be caused by more umami enhancing components such as Asp, Asn, Ala and 5 '-AMP, and considerable umami-potential smaller peptides in 60%-F. 60%-F also showed an antioxidant activity, and several antioxidant peptides was screened. The present study indicated the relationship between extract solution and taste characterization, which provided more possibility for the exploitation of umami substances and screening potential activity peptides.

关键词： High power ultrasound   Inactivation   Spores   Emulsion   Quality  

摘要： A combined supercritical carbon dioxide and high power ultrasound treatment (SC-CO2 + HPU) to inactivate spores while minimizing the physicochemical changes in emulsions was investigated. The inactivation kinetics were obtained for Bacillus subtilis, Bacillus pumilus and Geobacillus stearothermophilus spores and the effect of the treatment conditions on the quality of the emulsions was explored using response surface methodology. The treatment for 20 min at 95 degrees C and 350 bar was effective at inactivating B. subtilis and B. pumilus. Treated emulsions showed, in general, minimal changes in density and good stability, although the pH decreased and the droplet size increased. The treatment at 600 bar, 95 degrees C and 12.5 min permitted satisfactory B. subtilis and B. pumilus inactivation with minimal physicochemical changes in the emulsions. Therefore, the use of SC-CO2 + HPU could be a viable alternative for the preservation of emulsions using temperatures lower than those of thermal treatments.

关键词： Rubberized bitumen   Sustainability   Bio-modifier   Ultraviolet aging   Oxidation   Rheometry   Spectroscopy  

摘要： Promoting the use of scrap tire rubber and bio-modifiers in outdoor construction such as road pavements requires an in-depth understanding of their resistance to solar radiation which causes premature aging in outdoor constructions. Aging changes bitumen's colloidal stability, increasing the content of asphaltenes, and decreasing the content of aromatics as aging progresses. Bitumen's changes during aging include oxidation, ammatization, chain scission, and carbonization, which alter bitumen's chemical, physical, and mechanical properties. Here, we examine how exposure to ultraviolet radiation changes the physicochemical and mechanical properties of biomodified rubberized bitumen (BMR) containing various bio-modifiers. To do so, the physicochemical and mechanical properties of rubberized bitumen specimens containing bio-modifiers from castor oil (CO), corn stover oil (CS), miscanthus oil (MS), wood pellets oil (WP), and waste vegetable oil (WVO) were examined before and after they were exposed to ultraviolet radiation for 50, 100, and 200 h. The study results showed that the resistance of the abovementioned bitumens to aging caused by ultraviolet exposure was highly dependent on the source of the bio-modifier. The aging resistance was highest for CO-BMR and WP-BMR, followed by WVO-BMR, CS-BMR, and MS-BMR. This was attributed to the presence of unsaturated groups in CO and WP, which acted as sacrificial agents. In the case of WP, the improvement can also be attributed to the presence of high content of furfural. It should be noted that furfural has been used as a specialty antiaging chemical in industry. The study outcomes help manufacturers select modifiers for rubberized bitumen to enhance its resistance to UV aging and promote sustainability in construction.

关键词： Powders  

摘要： Effects of pH and heating on deamidation of whey protein concentrate (WPC) solution and functional properties of resultant spray-dried WPC powder were investigated. Temperature and heating time affected deamidation rates with the highest reactivities for WPC solutions heated at 120 degrees C for 15 min and 145 degrees C for 120 s. Deamidation sites were pH dependent: pH 3 induced more glutamine deamidation;pH 10 induced more asparagine deamidation. The functional properties of spray-dried WPC powders were also pH dependent. WPC solution adjusted to pH 3 and heated at 145 degrees C for 120 s (prior to spray drying) exhibited a reduction in solubility and foamability, but markedly improved foam stability of the resultant powders;meanwhile, the properties of powders were not significantly impacted by pH adjustment to 10.0 and heating at 145 degrees C for 120 s. However, pH 3 and 10 with and without heating significantly improved emulsifying properties of spray-dried WPC. (C) 2021 Elsevier Ltd. All rights reserved.

关键词： Amazonian region   Cassava flour   chemometrics   near‐   infrared spectroscopy   prediction  

摘要： Manihot esculenta flour (MEF) is the main energetic source for a major part of the population in the Amazonian region. In this study, near-infrared spectroscopy (NIRS) was used, for the first time, to predict physicochemical parameters of MEF. The water activity (a(W)), ash content, bulk density, moisture content, pH, geometric mean diameter (GMD) and colour parameters of L*, Cab* and h(ab) were determined for 106 samples of MEF. Calibration equations with independent validation were developed to predict all parameters using the partial least square regression method. The performance of models was evaluated by the root mean standard error of calibration (RMSEC) and validation (RMSEV), and R-2 values. The a(W) (RMSEC = RMSEV = 0.05), moisture content (RMSEC = 0.35%;RMSEV = 0.45%) and pH (RMSEC = 0.16;RMSEV = 0.18) could be predicted (R-2 > 0.727) by NIRS coupled to multivariate analysis. NIRS and multivariate analysis proved to be a powerful tool to predict multiple physicochemical parameters of MEF.

关键词： Rice   Comprehensive evaluation   High temperature tolerance   Grain-filling stage   Starch physicochemical indexes  

摘要： In order to compare the high temperature tolerance of six rice varieties, field experiments using interval sowing population were conducted to select sowing batches at high temperature and normal temperature during grain filling period. High filling temperature decreased significantly head milled rice rate, setback, amylose content and the proportion of the short chain of amylopectin, and increased obviously chalkiness, breakdown, gelatinization temperature, gelatinization enthalpy, and the proportion of the medium chain of amylopectin. Analysis of variance indicated significant differences with respect to physicochemical indexes of the starches from six rice varieties under high temperature during grain filling stage. In addition, five starch physicochemical indexes including apparent amylose content, setback, breakdown, chalkiness and gelatinization enthalpy showed more sensitivity to high temperature. These indexes could be considered as key indexes to evaluate the high temperature tolerance of these six rice varieties. The experimental results showed that the high temperature tolerance of the six varieties - Huanghuazhan, Y liangyou 957, Taiyou 390, Tianyouhuazhan, Zhongzao 39, Y liangyou NO 1 - ranged from strong to weak. The regression equation showed similar results and indicated that the high temperature tolerance of different varieties could be preliminarily evaluated using the key physicochemical indexes of starch.

关键词： Sulfonamide antibiotics   Contaminant transport   Adsorption   Emerging contaminant  

摘要： Sulfonamide antibiotics (SAs) are commonly used antibiotic classes in livestock worldwide. SAs are discharged to the environment and then may accumulate in rivers and aquifers, thereby diminishing water quality and the overall health of the ecosystem. While the occurrence and distribution of SAs in water environments have been the subject of numerous investigations, the fate and transport of SAs in aquifers have been less understood. In the present work, four of the most used SAs, including sulfadiazine (SDZ), sulfathiazole (STZ), sulfamethazine (SM2), and sulfamethoxazole (SMX), were selected for laboratory experiments and modeling analysis. The experiments were conducted in saturated columns filled with two common porous media, quartz sands and limestone grains. Results showed that the SAs had mobility changing on the order (from high to low) of SMX > SM2 > SDZ > STZ in the column, with SMX being the least absorbed SA by quartz sand or limestone grains. Moreover, calcium ions inhibited the transport of SAs more strongly than that of sodium ions, while the inhibitory effect was slightly enhanced with an increasing Na+ concentration from 0 to 10 mM. In contrast, the presence of humic acid facilitated the transport of SAs. Although the four SAs have similar molecular structures, their adsorption and transport characteristics were shown to be quite different. The dynamics of the adsorption and transport of SAs in groundwater can be effectively described by a two-site adsorption model coupled with advection and dispersion. This study sheds new light on the transport of SAs, contributing to a better understanding of how to control the presence and migration of antibiotics as new emerging contaminants in groundwater.

关键词： Corn starch   Pectin   Heat-moisture treatment   Retrogradation   Freeze-thaw stability  

摘要： The study investigates the role of pectin and heat-moisture treatment in modifying the physicochemical and structural properties of corn starch. The structural features and morphological, thermal and rheological properties of samples were characterized using techniques including microscope, SEM, DSC, FTIR, NMR, and rheometer. Results reveal that the pectin-starch mixture with the heat-moisture treatment shows an improved paste stability and a modified structure with a lowest value of retrogradation degree (39.7%), syneresis rate (6.33%), double helices content (26.5%), and leaching amylose content (22.7%). All of these can be ascribed to a fact that the heat-moisture treatment could enable a strong interaction of hydrogen bonds between pectin and starch molecules (amylose/amylopectin). The current findings suggest a potential use of the heat-moisturetreated pectin-starch paste in food industry.

关键词： Fischer-Tropsch synthesis   Nano catalyst   Cobalt   iron catalyst   Novolac phenolic resin  

摘要： The main approach of this study was to investigate the effect of the type of synthesis method on the improvement of catalyst performance in Fischer-Tropsch reaction. For this purpose, a series of the novel catalysts were synthesized using iron and cobalt nitrate salts, tetraethoxysilane and novolac phenolic resin by different method. These catalysts were abbreviated as M1-Co-Fe-novolac/SiO2, M2-Co-Fe-novolac/SiO2, and M3-Co-Fe-novolac/SiO2 and characterized using different techniques. The results of the Brunauer-Emmett-Teller and Fourier transform infrared techniques showed that M2-Co-Fe-novolac/SiO2 catalyst has a higher surface area than the other two ones. This catalyst was analyzed by using X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray, and temperature-programed reduction (TPR) techniques. The XRD results confirmed the appearance of suitable active phases, such as metal phase, carbide, and low oxidation state of metals. Based on TPR results, the lower reduction temperature, compared with similar samples, confirmed the high activity of the M2-Co-Fe-novolac/SiO2 catalyst. Catalytic activity and selectivity for Fischer-Tropsch reaction were investigated in the standard conditions by using catalytic tests. The high conversion percentage of CO indicated high activity of the catalyst. On the other hand, the olefin to paraffin ratio (O/P), which was a criterion for catalytic efficiency in industrial, was also acceptable.