教学课程资源库 更多>>

关键词： Red dragon fruit   Alcoholic fermentation   Torulaspora delbrueckii   Pectinase treatment  

摘要： Red dragon fruit is a popular tropical fruit that has been highly prized for its health benefits partially attributed to the high antioxidant content. Nevertheless, besides being consumed fresh, further processing into juice or other products is scarce due to its high pectin content that presents a challenge in industrial processing. In this study, we evaluated the effects of pectinase pre-treatment on red dragon fruit wine fermented with Torulaspora delbrueckii. Pectinase enzyme (Pectinex (R) Ultra SP-L, added at 0.1% v/v) was applied after pasteurization of juice followed by fermentation with T. delbrueckii at 20 degrees C for 14 days. Pectinase pre-treatment did not affect the yeast growth, nor the production of ethanol (8% v/v) and glycerol (6 g/L), but significantly increased juice/wine yield by 16% v/v. In addition, pectinase treated samples after fermentation remained significantly higher levels of residual nitrogen containing compounds, indicating unfavorable fermentation conditions and impaired metabolism of the yeast. Moreover, fermented pectinase treated samples possessed the aroma compound profiles with enriched esters and terpenes but decreased higher alcohols. Furthermore, pectinase treatment increased the total phenolic content, but decreased betacyanins content and color intensity compared to control sample. The findings would have practical significance for diversifying products from red dragon fruit.

关键词： Starch   FTIR   Quality Protein Maize   Modification   pasting properties  

摘要： Quality protein maize (QPM) is a biofortified maize rich in lysine and tryptophan, essential amino acids required in human nutrition. This research therefore characterizes native and modified starches from QPM by evaluating the physicochemical properties, Fourier transform infrared spectra (FTIR), and pasting properties. The native QPM starch was modified by oxidation, acetylation, pregelatinization, and acid thinning techniques. The starch yield of native QPM was 43.80%, while that of modified starches were from 88.22 to 98.34%. The moisture content of the native and modified starches was from 4.56 to 9.20 g/100g. Modifications significantly (P <= 0.05) reduced the lipid, protein, and amylose contents of the QPM. While the native starch had 0.72 g/cm(3)bulk density, modified starches were between 0.59 and 0.88 g/cm(3);chemical modification reduced the bulk density and physical modification increased it. In addition, all the modifications except oxidation significantly (P <= 0.05) increased water absorption capacity. The oil absorption of the starch samples was increased by modification techniques used with the exception of physical modification. Chemical modification reduced the viscosity of QPM starch while physical modification increased it. The reducing sugar content of the starch was reduced by both the physical and chemical starch modification techniques. Acetylated sample exhibited the highest swelling power while acid-thinned sample had the least. The major functional groups identified via FTIR were OH, C-H, C=H, and C equivalent to H. Modifications did not affect the functional groups as all the native and modified starches (except oxidized sample) all have similar spectrum and bands stretch. Practical Application The study contributes to existing knowledge on valorization of modified starch from quality protein maize. Profiling the chemical attributes of modified starches is especially valuable in novel food processing techniques.

关键词： Allium cepaL   functional properties   onion   physicochemical properties   processing conditions   total polyphenols  

摘要： Onion (Allium cepaL.) is one of the most perishable consuming vegetable in the world as an aromatic seasoning and for its health promoting bioactive compounds. However, drying and blanching are two essential thermal treatments in vegetables processing which lead to considerable changes in their properties. This study investigated the effects of temperature (70, 80, and 90 degrees C), time (2, 4, 6, and 8 hr), and blanching (100 degrees C for 5 min) followed by drying at 70 degrees C for 8 hr on the drying kinetics, physicochemical (Ash and total polyphenol content, pH, and titratable acidity), and functional (water solubility index and particle size) properties of onion powder, as well as compared to local market powders. The variety violet of Galmi was used. The results revealed that the moisture content of non-blanching powder was below 13 +/- 0.76 g/100 g with pH under 4. In addition, total polyphenol contents were higher than 512 +/- 15.06 mg GAE/100 g DM. These powder showed a small particle size (under 400 mu m) and high solubility (<= 81.36 +/- 2.3 g/100 g DM). Blanching did not affect the powders quality. Local market powders showed a lowest total polyphenol content (386.60 +/- 10.02 mg GAE/100 g DM) with large particles (<= 800 mu m) and a lowest solubility (65.33 +/- 1.62 g/100 g DM). Drying at 80 degrees C for 8 hr without blanching emerge as the best compromise drying conditions resulting in optimal physico-chemical and functional properties (10.8 +/- 0.8 g/100 g, 846.6 +/- 15.09 mg GAE/100 g DM and 88.12 +/- 2.31 g/100 g DM of moisture content, total polyphenol content, and water solubility index, respectively. These findings can contribute to reduce postharvest losses in onion and to stimulate the industrialization of onion enriched-powder production in Africa. Practical Application This study provides critical information on onion properties profile during its transformation, on which processor might build on its decision to make an appropriate choice

关键词： Zea mays   By-product   Bakery good   Toasted breads   Dietary fiber  

摘要： The aim of this study was to assess physicochemical and sensory viability of toasts developed from the partial replacement of wheat flour (WF) by maize biomass flour (MBF). Different levels of MBF (0, 5, 10, 15 and 20 g 100 g(-1)) were used. Data obtained were evaluated by univariate and multivariate analyses. The level of replacement of WF by MBF influenced all physicochemical properties of the toast. Moisture (5.67-7.12 g 100 g(-1)), hardness (56.67-131.66 N), chroma of crust and crumb (29.86-30.27 and 19.76-25.83, respectively), and hue angle of crust and crumb (60.32 degrees-64.79 degrees and 81.41 degrees-82.06 degrees, respectively) were increased;and area (2286.4-1658.1 mm(2)), specific volume (3.47-1.83 mL g(-1)) and luminosity of crust and crumb (62.39-59.67 and 65.49-62.54, respectively) were decreased as the level of substitution of WF by MBF increased. The toasts did not present microbiological risk. The formulations with higher sensory acceptance were 5 and 15 g 100 g(-1) of MBF, being considered rich in proteins (16.25 and 15.43 g 100 g(-1), respectively) and rich in dietary fibers (12.10 and 16.02 g 100 g(-1), respectively), therefore with high nutritional and functional values. The production of toasts with partial replacement of WF by MBF is feasible in relation to physicochemical and sensory characteristics, which it may stimulate exploitation of this by-product and sustainable production of baked goods.

关键词： Corrosion resistance  

摘要： Abstract: Physicochemical characteristics of the nitrogen-alloyed steel melt of the 04Kh20N6G11M2AFB grade (nitrogen content 0.47–0.49%) are investigated by using the torsional vibration method of a crucible with metal in the atmosphere, which provides a stable nitrogen content during the experiment (80% nitrogen and 20% helium). Using the method sensitivity to the aggregate state of the tested substance, at a heating rate of 0.0033–0.0050 K/s, the liquidus temperatures are experimentally determined for the 04Kh20N6G11M2AFB steel (1660–1666 K) and low nitrogen steel ([N] = 0.063%) with the identical content of other elements (1685–1690 K). These results make it possible to recommend the value of the coefficient –60 K/% [N] for the calculated assessment of nitrogen influence on the liquidus temperature of complex and high alloy steels. The viscosity of the 04Kh20N6G11M2AFB steel melt is relatively high ((11.5 ± 0.7) ×10–7 m2/s) in comparison with the traditional austenitic steels ((8.2 ± 0.2) × 10–7 m2/s) with a relatively small partial effect of nitrogen. A significant nonequilibrium of the structural state of the 04Kh20N6G11M2AFB steel melt is revealed by the high-temperature viscometry methods. The comparative analysis of polytherms and kinematic viscosity isotherms of the 04Kh20N6G11M2AFB steel melt and its low nitrogen ([N] = 0.063%) analogue makes it possible to conclude that the nitrogen presence in concentrations close to saturation plays a decisive role in the melt nonequilibrium level and low relaxation rate. This is confirmed by the results of special experiments on saturation with nitrogen of low nitrogen steel, in which a sharp increase in nonequilibrium of the melt structural state is recorded when nitrogen concentration in metal reaches the limiting values (0.45–0.50%). There is a potential possibility to increase and stabilize the operational properties of corrosion resistant nitrogen-alloyed steels due to reducing the melt’s structural state nonequil

关键词： bicarbonate soluble P   arid and semi-arid regions   humic acid   Langmuir   P adsorption   pH   runoff P losses   runoff sediment   soil texture  

摘要： Phosphorus depletion from cultivated lands by runoff is a significant contributor to soil chemical degradation. Our objective was to elucidate the mechanisms through which soil and organic matter amendments affect rain-induced runoff P losses in Mediterranean soils. Clay, loam, and loamy sand mixed with noncomposted activated sludge (AS), manure compost (MC), industrial humic acid (HA), orthophosphate (Pi), or inositol hexaphosphate (IHP) were subjected to six consecutive artificial rainstorms. Adding amendments significantly increased runoff available Pi loss (the sum of solution and sediments bicarbonate extractable Pi) for all soils. The order of loss (Pi, mg m(-2)) was soil dependent;greatest and lowest in the loam and loamy sand, respectively (loam: Pi[270] > IHP[128] > AS[108] > MC[97] > HA[49] > Control[33], and loamy sand: AS[42] > HA[23] > Pi[22] > IHP[18] > MC[13] > Control[4]), although order of runoff and soil loss were clay > loam > loamy sand. Treating with IHP and Pi at a similar total P level led to comparable cumulative total-P runoff losses, but runoff available Pi loss was much greater in the Pi treatment of soils with higher clay content (clay > loam > loamy sand). A derived isotherm relating sediment Olsen Pi to dissolved reactive Pi (DRP) concentration in runoff was found useful for estimating runoff Pi losses from measured DRP, runoff volume, and sediment concentration. The results could be explained by the impact of the amendments on soil structure stability, sealing, runoff, and erosion levels associated with soil physical and chemical degradation.

关键词： Biochar   Soil micro-ecological environment   Physicochemical properties   Microbial communities   Tobacco  

摘要： Biochar was increasingly used in agriculture soil amendment and has received widespread attention due to its potential to improve soil micro-ecological environment and crop growth. The raw material of the biochar used in this study is peanut shell, which is mixed with other organics and minerals to become a mineral-enhanced biochar under heating conditions (220 degrees C). When the third season crop is finished, we evaluated black soil physicochemical properties, microbial communities, and crop growth in long-term agricultural trials. Four treatments were set up: no amendment (control CK), nitrogen fertilizer only (70 kg ha(-1) N), enhanced biochar only (5 t ha(-1)B), and nitrogen fertilizer (70 kg ha(-1)) + enhanced biochar (5 t ha(-1)) (NB). The enhanced biochar promotes crop growth and increased the richness of the bacterial community, while reducing the richness of the fungal community. Nitrogen fertilizer + enhanced biochar increased soil microbial biomass carbon, nitrate nitrogen, and ammonium nitrogen by 43.75, 7.25, and 19.28%. In addition, we found changes in bacterial community were closely related to soil organic carbon, while changes in fungal community structure were closely related to soil carbon to nitrogen ratio. And the soil organic carbon and soil carbon to nitrogen ratio of biochar treatment were increased by 5.64 and 6.25% compared with fertilizer treatment, respectively. We concluded that enhanced biochar improved the soil more effectively and made the soil more conducive to crop growth. Regulating the microbial community by improving the physicochemical properties of soil was an important way to improve the stability and condition of the soil system with biochar. An enhanced biochar was of great significance for circular development of agriculture and soil improvement in Northeast China.

关键词： Fruits  

摘要： The identification of tomato maturity is significant to extend the fruit shelf life and generate the scientific processing strategy. Tomato maturation is a gradual process, and the internal physicochemical characteristics are most related to maturity states. Merely choosing visual features to identify maturity would cause discriminant errors. This study designed a simple and effective identification method for tomato maturity by integrating color moments and physicochemical indices. The color moments were extracted by an adaptive K-means clustering image processing program, and firmness, soluble solid content and sensory evaluation were measured by professional techniques. The optimal multidimensional index set was formulated according to color moments and physicochemical indices simultaneously. To reduce the confusion between adjacent stages, a novel multinomial logistic regression with kernel clustering (MLRKC) method was designed to identify maturity, and the accuracy was 95.83% for tomato testing set. Moreover, the traditional image features set and some classic methods were applied to verify the performance of proposed method, respectively. Finally, the proposed method was applied to identify the tomatoes in the realistic circumstance. The identification results demonstrated satisfactory performances and promising applications of MLRKC method integrating color moments and physicochemical indices. Practical Applications Tomato is a climacteric fruit which could mature after harvesting. Identification tomato maturity stage is significant to decide the optimal transportation modes, inventory strategies and processing technology. Traditional methods for identifying tomato maturity were high-cost and complicated, which were inefficient for small-scale production. The method proposed in this study could simply the identification steps and reduce the operating cost, and also provide more accurate and valuable information. The investigated theoretical basis could be in

关键词： potato protein isolate   hydrolysate   physicochemical characteristics   solubility   antioxidant  

摘要： This study investigated the physicochemical characteristics of potato protein isolate hydrolysate (PPIH) and its antioxidant activity. Potato protein isolate (PPI) was hydrolyzed into PPIH by the proteases bromelain, Neutrase, and Flavourzyme. Compared with PPI, the resulting PPIH had a lower molecular weight (MW, from 103.5 to 422.7 Da) and smaller particle size (<50 nm), as well as a higher solubility rate (>70%) under acidic conditions (pH 3-6). PPIH presented good solubility (73%) across the tested pH range of 3-6. As the pH was increased, the zeta potential of PPIH decreased from -7.4 to -21.6. Using the 2,2 '-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical-scavenging assay, we determined that the half-maximal effective concentration (EC50) values of ascorbic acid, PPIH, and PPI were 0.01, 0.89, and >2.33 mg/mL, respectively. Furthermore, PPIH (50 mu g/mL) protected C2C12 cells from H2O2 oxidation significantly better than PPI (10.5% higher viability rate;p < 0.01). These findings demonstrated the possible use of PPIH as an antioxidant in medical applications.

关键词： DeNO(x)   Selective catalytic reduction (SCR)   Catalyst   Red mud   Cerium precursors  

摘要： Red mud, as industrial solid waste, causes severe environmental problems such as soil alkalization and groundwater pollution. In this work, we researched and developed the red mud as a selective catalytic reduction catalyst for NOx removal with NH3 (NH3-SCR). After selective dissolution and specific heat treatment, different Ce precursors were used to modifying its physical and chemical properties. The results showed that Ce(NO3)(3) and Ce(NH4)(2)(NO3)(6) modified red mud (RMcn and RMcan) had excellent SCR performance below 300 degrees C. Ce(SO4)(2) modified red mud (RMcs) showed relatively low NOx conversions at 200-300 degrees C. The redox property was improved with the Ce(NO3)(3) and Ce(NH4)(2)(NO3)(6), while depressed with the Ce(SO4)(2). Agglomerates generated on the RMcs and blocked the accumulated pores due to the formation of Ce-2(SO4)(3). The surface acidity of RMcs enhanced with increased adsorption for ammonia. However, these new adsorbed ammonia species, highly related to the sulfate from the Ce-2(SO4)(3), were inert and did not react with the adsorbed or gaseous NO species at 200-300 degrees C. The abundant surface lattice oxygen from CeO2 microcrystals improved the catalytic oxidation capacity of the RMcn and RMcan. (C) 2020 Elsevier Ltd. All rights reserved.