教学课程资源库 更多>>

关键词： Physicochemical properties  

摘要： Generally, heat-moisture treatment (HMT) modified starch is prepared at atmospheric pressure without stirring, which is time-consuming (8 similar to 24 hr) and uneven heating. The wheat flour (WF) and starch (WS) were modified by HMT in a high pressure reactor with a stirrer. Physicochemical properties of WF and WS after HMT for 30 min with different moisture and temperature conditions were investigated. Compared to native samples, decrease in peak viscosity, and increase in gelatinization temperature were found in both WF and WS after HMT treated at moisture of 25% and 30%. A decrease in rapidly digestible starch and slowly digestible starch content while an increase in resistant starch content was found for all moisture levels. By studying the effect of heat treatment on the digestibility of starch and flour, and the application of heat treatment in noodles, it provides a theoretical basis for the development of staple food products suitable for diabetic patients. Practical applications Resistant starch (RS) within a calorie-controlled diet is thought to be beneficial in protecting against metabolic syndrome and colon cancer. With the acceleration of the pace of life, a diet high in sugar and fat and a sedentary lifestyle, which can led to a rapid rise in the global incidence of diabetes. Therefore, reasonable diet is significant to stabilize and improve the condition of diabetic patients. Wheat flour provides the basis for breads and other baked products including noodles. Noodles are one of China's traditional staple foods. It is of great importance to explore and develop the noodle recipe suitable for the diabetic diet. Heat moisture treatment is an important physical treatment method used to improve the poor functional properties of native starch and is specially favorable for food applications. In this study, RS of wheat flour and starch was significantly increased during heat-moisture treatment. By studying the effect of heat treatment on the digestibility o

关键词： Bio-oil   Heavy fraction   Pyrolysis   Heating rates   Evolution  

摘要： The effects of heating rate on the evolution of tar obtained from heavy fraction of bio-oil (HB) were revealed by the change of elements, functional groups and chemical compounds. The results showed that slow heating rate had a negligible effect on the physicochemical properties of HB from 400 to 800 degrees C. By contrast, decomposition, radical recombination and polymerization reactions could occur at fast heating rate. A clear trend of increasing tar yields was monitored from 300 - 500 degrees C. However, a significant decrease was observed at high temperature (600 - 800 degrees C). Through elemental analyzer, C content in tar expanded with the temperature increasing, whereas N content remained unchanged. Nuclear magnetic resonance (NMR) spectroscopy results indicated that the carboxyl functional groups would be destroyed at high temperature. Furthermore, the concentrations of aromatics showed a trend to increase accompanied by a simultaneous decrease in phenols with the temperature rising according to gas chromatography/mass spectrometer (GC/MS) analysis.

关键词： Bi2WO6   CeO2   Iron doping   Nanocomposite   Photocatalytic activity   Wastewater treatment  

摘要： Fe-doped Bi2WO6/CeO(2)nanocomposite materials were prepared by co-precipitation and hydrothermal methods. The physicochemical properties and photocatalytic activities of Bi2WO6/CeO(2)nanocomposites after doping with Fe(3+)ions were systematically investigated. The 0.2Fe-doped Bi2WO6/CeO(2)nanocomposites exhibited the optimal photocatalytic activity in the degradation of rhodamine B (RhB), reaching to 62% degradation after 120 min irradiation, which was 10.3 and 2.7 times higher than CeO(2)and Bi2WO6, respectively. The improved photocatalytic activity was mainly ascribed to the enhanced charge carrier separation efficiency of the direct Z-scheme heterojunction system. Moreover, the effective trapping of photogenerated electrons and holes by iron ions inhibits the electron-hole recombination. By a trapping experiment, the main radicals (O-2(center dot-)) in the photocatalysis experiment were further ascertained. Finally, we proposed the photocatalytic mechanism of Fe-doped Bi2WO6/CeO(2)nanocomposite for RhB degradation.

关键词： chromite rocks   chromium oxide   enrichment   filler   refractory material  

摘要： The mineral and chemical compositions of the chromite raw materials of the Karelia-Kola region are studied, and physical and chemical processes for producing refractory materials from chromite concentrate are established. The phases and structure formed during drying, firing, and service are determined. The dependence of some refractory properties on their material, grain, and phase compositions is established.

关键词： Feta cheese   Physicochemical parameters   Volatiles   Fatty acids   Geographical differentiation   Chemometrics  

摘要： The present study aimed to differentiate feta cheese samples produced in northern Greece according to geographical origin. In 2006 the EU, through Council Regulation (EC) 510/2006 succeeded in giving a competitive advantage to the quality and diversity of the Union's agricultural production by adopting PDO (Protected Designation of Origin) and PGI (Protected Geographical Indication) regulations among EU members. Feta cheese has been approved as a Greek PDO product in 2008. Feta cheese samples from the regions of Ioannina, Arta, Thessaloniki, Larissa and Evros, were subjected to physicochemical, fatty acid and volatile compounds analyses. Using multivariate statistical analysis (MANOVA/LDA) and the cross-validation method, cheese samples achieved a correct classification rate of 61.8%, 65.8% and 88.2% based on physicochemical parameters, volatile profile and fatty acid composition, respectively. Fatty acids were the most efficient parameters for the differentiation of cheese samples. When all three above parameters were combined the correct classification rate of cheese samples increased to 89.5%.

关键词： Palm empty fruit bunches   Pyrolysis   Experimental design   Antioxidant properties  

摘要： Residues of the palm oil agro-industry (palm empty fruit bunches - EFB) were pyrolysed to produce biofuels. Effects of several parameters on the slow pyrolysis process were evaluated using the central compound rotational design (DCCR) for modelling and optimization the process conditions aiming the maximum yield of bio-oil. After pyrolisis and using various approaches the products were characterized with emphasis on bio-oil. The response surface methodology and desirability function indicate that the temperature was the most influential parameter in regard to the liquid yield, in which the optimum pyrolysis conditions were: temperature of 628.2 degrees C and N-2 flow rate of 0.259 L/min. The empirical relationships for the bio-gas, bio-oil, and bio-char were carried out from a second-order polynomial equation adequately describing the nonlinear behaviour of the experimental data with a precision of approximately 85%. Gas chromatography-mass spectrometry (GC-MS) and Fourier Transformer infrared (FTIR) analysis shows that bio-oil has a high content of oxygenated compounds with four main components: hexadecanoic acid methyl ester (25.57 area%), nonane (12.51 area%), n-hexadecanoic acid (10.66 area%) and phenol (10.13 area%). Moreover, high-performance thin-layer chromatography (HPTLC) analysis showed the bio-oil is very promising for biodiesel-based automotive additives preventing oxidation of the bisallylic methylene groups and the consequent generation of free radicals. Biochar showed low yield (27.52%) but good energy capacity, with a calorific value of 19.27 MJ/kg. Regarding to gases production, CO2 and CH4 are the main compounds observed in optimized conditions suggestion its use like raw material in the energy production.

关键词： Ultrasound-assisted immersion freezing   Chicken breast   Quality   Physicochemical properties  

摘要： This paper evaluated the impact of air freezing (AF), immersion freezing (IF) and ultrasound-assisted immersion freezing (UF) at different power levels (125, 165, 205 and 245 W) on the muscle quality and physicochemical properties of chicken breast. As the ultrasonic power increased, the total freezing time of the UF samples first decreased and then increased. UF at 165 W (UF-165) remarkably shortened the freezing time of the samples. Microstructure analysis showed that UF-165 samples had the smaller and more uniform ice crystals. In addition, UF-165 effectively reduced the thawing and cooking losses (P<0.05) compared to those of the AF and IF samples. Low field nuclear magnetic resonance analysis proved that the T-21 and T-22 of the UF-165 samples were shorter than those of the AF and IF samples (P<0.05), which meant that UF-165 reduced the mobility and loss of immobilized water. Overall, the appropriate ultrasonic power had a positive effect on maintaining the quality of frozen chicken breast. (C) 2020 Elsevier Ltd and IIR. All rights reserved.

关键词： honey   electronic nose   electronic tongue   sensory analysis   adulteration  

摘要： Honey is produced by honeybees and is used as a food and medical product. Adulteration of honey has been a problem for several years now because of the relatively high price of honey on the market according to its valuable composition. The aim of our study is to determine the physicochemical properties of authentic Hungarian linden and acacia honeys (pure samples or manipulated ones blended with sugar syrup) as well as commercially available blends of European Union (EU) non-European Union (non-EU) honeys. Authentic linden and acacia were blended with sugar syrup at 10%, 20% and 50% concentration levels, and physicochemical properties were determined according to the methods of the International Honey Commission. Our objectives also included testing of the performance of electronic sensory techniques (electronic tongue (ET) and electronic nose (EN)) in the detection of adulteration, and the results are compared to the sensory profile analysis. The results provide good average recognition and prediction abilities for the classification of adulterated and authentic honeys (>90% for ET and higher than >80 for EN). Misclassifications were found only in the case of honey with 10% added sugar syrup. The methods were also able to reveal adulteration of independently predicted samples.

关键词： Calcium  

摘要： Finger millet being underutilized but highly nutritious millet was explored for nutritional characteristics. Twelve cultivars of finger millet were found to be a potential source of proteins (7.19%-12.56%), crude fibers (3.17%-5.83%), crude fat (1.07%-1.87%), and ash or mineral content (2.81%-3.61%) as well as a rich source of minerals such as Cu (0.61-1.62 mg/100 g), Mn (4.01-7.44 mg/100 g), Fe (3.97-8.04 mg/100 g), Zn (2.08-4.50 mg/100 g), and Ca (318-659 mg/100 g). Cultivars were screened out for the highest content of calcium and the cultivar GPHCPB-149 richest in calcium (659 mg/100 g) was utilized for supplementation in biscuits at different proportions, that is, 0, 25, 50, and 75%. A significant (p <= .05) increase in the calcium and crude fiber contents was reported with increased incorporation of finger millet in biscuits. Sensory evaluation studies concluded that finger millet flour was successfully incorporated up to 50% in wheat flour for the preparation of biscuits. Practical applications The study showed that finger millet is a rich source of nutrients and has great potential to be utilized for the development of functional bakery products. It can be successfully incorporated up to 50% with wheat flour for the preparation of functional bakery products. Finger millet incorporated biscuits were found to contain higher levels of crude fiber, calcium, iron, and zinc contents than control biscuits and may offer the inherent health benefits of finger millet to the consumers by alleviating the deficiency of calcium and prevention of other lifestyle diseases.

关键词： Malted sorghum   Starch   Malting   Rheology   Amylose   Reducing sugars  

摘要： The objective of this study was to evaluate the physicochemical changes that occur in sorghum starch during malting to determine its potential in the beer industry. The results showed that the physicochemical properties of amorphous amylose and amylopectin of starch over time are modified during the germination while its crystalline structure is not affected. During the different stages of malting the SEM images showed the progress of the enzymatic attack in the starch granule. Germination and the increase in reducing sugars supported amorphous starch degradation. The X-ray diffraction pattern confirmed that during malting, the crystalline structure in starch remained without changes. The pasting profile showed high values for peak and final viscosity, once the sorghum was soaked and decreasing over the malting process. These changes are associated with starch degradation and amylopectin debranching, increasing the reducing sugars.