非均相固体碱催化剂制备生物柴油的工艺优化

以菜籽油为原料,运用Mg/Al复合固体作为碱性催化剂制备生物柴油.采用五因子二次正交旋转组合设计,研究醇油比,催化剂用量,反应时间,反应温度,搅拌强度五个因子对生物柴油得率的影响,利用SAS8.1中的响应面分析程序RSREG建立并分析了五个因子对得率影响的数学模型.结果表明,所得回归方程达显著水平,拟合情况良好;五个因子对得率的影响大小依次是催化剂用量>醇油比>搅拌速度>反应时间>反应温度.最佳反应温度为70℃,催化剂用量为6%,醇油比5:1,反应时间8h,搅拌强度500r/min,生物柴油的得率可达90%,其指标基本达到美国的ASTM标准和德国的DINE标准.     

鲜水葫芦与其汁液厌氧发酵产沼气效率比较

为开发高效处理水葫芦的厌氧发酵产沼气技术,该文在35℃中温条件下,分别以鲜水葫芦和经固液分离的水葫芦汁为发酵底物,应用实验室自行设计的2套完全混合搅拌反应器(CSTR)进行了厌氧发酵比较研究。结果表明,以水葫芦为底物直接进行厌氧发酵,最大容积负荷为2.0kg/(m3·d),挥发性固体(VS)产气率为267mL/g,容积产气率为0.61m3/(m3·d),滞留期为27d,平均甲烷体积分数为58%,而以水葫芦汁为底物,COD(化学需氧量)容积负荷可达6.0kg/(m3·d),原料(COD)产气率为231mL/g,容积产气率可达1.4m3/(m3·d),平均甲烷体积分数为66%,滞留期仅需2.4d,COD平均去除率达85%,MLVSS(挥发性悬浮物浓度)平均去除率可达88%。因此,对水葫芦进行固液分离,以水葫芦汁作为厌氧发酵原料可大大提高处理效率,为水葫芦资源化利用提供了一条新途径。     

Characterization of the total free radical scavenger capacity of vegetable oils and oil fractions using 2,2-diphenyl-1-picrylhydrazyl radical

The total free radical scavenger capacity (RSC) of 57 edible oils from different sources was studied: olive (24 brands of oils), sunflower (6), safflower (2), rapeseed (3), soybean (3), linseed (2), corn (3), hazelnut (2), walnut (2), sesame (2), almond (2), mixture of oils for salad (2), "dietetic" oil (2), and peanut (2). Olive oils were also studied according to their geographical origins (France, Greece, Italy, Morocco, Spain, and Turkey). RSC was determined spectrophotometrically by measuring the disappearance of the radical 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)) at 515 nm. The disappearance of the radical followed a double-exponential equation in the presence of oils and oil fractions, which suggested the presence of two (fast and slow) groups of antioxidants. RSC was studied for the methanol-soluble phase ("methanolic fraction", MF) of the oil, the fraction nonsoluble in methanol ("lipidic fraction", LF), and the nonfractionated oil ("total oil"; TF = MF + LF). Only olive, linseed, rapeseed, safflower, sesame, and walnut oils showed significant RSC in the MF due to the presence of phenolic compounds. No significant differences were found in the RSC of olive oils from different geographical origins. Upon heating at 180 degrees C the apparent constant for the disappearance of RSC (k(T)) and the half-life (t1/2) of RSC for MF, LF, and TF were calculated. The second-order rate constants (k2) for the antiradical activity of some phenolic compounds present in oils are also reported.     

Beet sugar syrup and molasses as low-cost feedstock for the enzymatic production of fructo-oligosaccharides

Sugar syrup and molasses from beet processing containing 620 and 570 mg/mL sucrose, respectively, were assayed as low-cost and available substrates for the enzymatic synthesis of fructo-oligosaccharides (FOSs). A commercial pectinase (Pectinex Ultra SP-L, from Aspergillus aculeatus) characterized by the presence of a transfructosylating activity was used as a biocatalyst. The FOS production increased when lowering the initial pH value of syrup (7.5) and molasses (8.9) to 5.5. Sugar syrup and molasses were diluted in order to reduce substrate viscosity; interestingly, the percentage of FOS with regards to total sugars remained almost constant, which indicated a high transferase-to-hydrolase ratio for this enzyme. Kinetics of FOS production was analyzed. Using approximately 10 U transfructosylating activity per g sucrose, the FOS concentration reached a maximum of 388 mg/mL after 30 h using syrup and 235 mg/mL in 65 h with molasses. These values corresponded to approximately 56 and 49% (w/w), respectively, of the total amount of carbohydrates in the mixture. The enzyme was also covalently immobilized on an epoxy-activated polymethacrylate-based polymer (Sepabeads EC-EP5). We found that immobilized Pectinex Ultra SP-L can be efficiently applied to the synthesis of FOS using syrup and molasses as substrates.     

设施菜地WHCNS_Veg水氮管理模型

与一般大田作物相比,设施菜地集约化程度高、水肥投入量大,加上蔬菜根系浅,土壤养分淋失严重,不仅浪费资源,而且极易引起地下水污染等生态环境问题。定量研究设施蔬菜不同生长阶段的土壤水分动态和氮素去向是制定合理水氮管理方案的基础。该研究在农田土壤水热碳氮模拟模型（soil water heat carbon nitrogen simulator,WHCNS）的土壤水分、碳氮循环模块的基础上,耦合了蔬菜生长发育过程模型,构建了适用于设施菜地水氮管理的机理模型WHCNS_Veg。分别利用山东寿光的设施黄瓜和天津武清的设施番茄田间观测数据,主要包括不同水氮管理措施下实测的土壤水分（含水率和基质势）、土壤氮素（硝态氮含量和淋失量）、植株吸氮量和蔬菜可售卖鲜产量,对WHCNS_Veg模型进行了校准与验证。结果表明,作物生物学指标的模拟精度要高于土壤指标,模拟的黄瓜、番茄产量和植株吸氮量的相对均方根误差不大于12.1%、一致性指数不小于0.934和Nash-Sutcliffe效率系数不小于0.829。土壤指标中,土壤含水率的模拟效果也较好,相对均方根误差、一致性指数和Nash-Sutcliffe效率系数的范围分别为6.2%～9.1%、0.851～0.960和0.477～0.846;其次是土壤硝态氮含量和淋失量,相对均方根误差范围分别为22.2%～40.1%和4.6%～26.0%,Nash-Sutcliffe效率系数范围分别为?0.810～0.636和0.442～0.956。模型对土壤基质势动态模拟的精度相对较低,相对均方根误差、一致性指数和Nash-Sutcliffe效率系数范围分别为22.9%～30.1%、0.223～0.846和?6.344～0.113,主要是滴灌条件下模拟效果较差导致的,说明需要进一步提高滴灌条件下土壤基质势的模拟精度。总体来看,WHCNS_Veg模型较好地模拟了不同水氮管理条件下土壤水氮动态和蔬菜生物学指标,该模型在设施菜地水氮管理方面具有较大的应用潜力。     

Determination of nonprotein amino acids and betaines in vegetable oils by flow injection triple-quadrupole tandem mass spectrometry: a screening method for the detection of adulterations of olive oils

A novel screening method using an automated flow injection electrospray ionization tandem mass spectrometry system is proposed for the simultaneous determination of five nonprotein amino acids (β-alanine, alloisoleucine, ornithine, citrulline, pyroglutamic acid) and three betaines (glycine betaine, trigonelline, proline betaine) after derivatization with butanolic HCl. MS/MS experiments were carried out in a triple-quadrupole instrument using multiple reaction monitoring mode in <2 min. The proposed method provided high fingerprinting power to identify the presence of five of the studied compounds in different types of vegetable oils (soybean, sunflower, corn, olive) with LODs at parts per billion levels. The method was validated, and different mixtures of extra virgin olive oil with seed oils were analyzed, achieving the typification for the detection of adulterations in extra virgin olive oils up to 2% w/w. The nonprotein amino acid ornithine was confirmed as a marker for adulteration in the olive oils analyzed.     

Development of a biocatalytic process for the production of c6-aldehydes from vegetable oils by soybean lipoxygenase and recombinant hydroperoxide lyase

Volatile C6- and C9-aldehydes and alcohols are widely used as food flavors to reconstitute the "fresh green" odor of fruits and vegetables lost during processing. To meet the high demand for natural flavors, an efficient, cheap, and versatile biocatalytic process was developed to produce C6-aldehydes on a large scale. Vegetable oils were converted by soybean lipoxygenase and recombinant hydroperoxide lyase into hexanal and (2E)- or (3Z)-hexenal. In contrast to plant extracts, generally used as enzyme sources, high molar conversions were obtained with recombinant hydroperoxide lyase (50% for hexanal and 26% for hexenal formation), and no side products were formed. Furthermore, recombinant hydroperoxide lyase lacks isomerase activity, allowing production of (3Z)-hexenal, which could not be obtained in previously described processes. Recombinant hydroperoxide lyase is stable and can be stored at 4 degrees C for 1 month without significant loss of activity.     

Detection and prediction of hydrolytic rancidity in milk by multiple regression analysis of short-chain free Fatty acids determined by solid phase microextraction gas chromatography and quantitative flavor intensity assessment

The objective was to establish a method for detecting and predicting hydrolytic rancidity in milk by correlating quantitative sensory data with individual short-chain free fatty acids (FFA) (C(4)-C(12)) in milk determined by solid phase microextraction and gas chromatography (SPME-GC). A FFA-based equation for determining rancid flavor intensities in milk was derived by stepwise regression analysis. A highly significant (p < 0.001) correlation coefficient (R (2)) of 0.84 indicated that rancidity scores were dependent on FFA obtained by SPME-GC and that a good proportion of the variation in the rancidity scores was explained by the model. When rancidity scores were predicted for 19 commercial milks, one sample was found to be distinctly rancid by the statistical model and by the trained sensory panel. The rest of the samples were found to be nonrancid by either method. Thus, the predicting power of the model was shown because there was 100% correct flavor classification for the samples tested.     

Preparation of spread oils meeting U.S. Food and Drug Administration Labeling requirements for trans fatty acids via pressure-controlled hydrogenation

On July 11, 2003, the U.S. Food and Drug Administration (FDA) announced final regulations for trans fatty acid (TFA) labeling. By January 1, 2006, the TFA content of foods must be labeled as a separate line on the Nutrition Facts label. Products containing <0.5 g of TFA/14 g serving may be declared as zero. This paper describes technologies allowing compliance with TFA labeling requirements. Soybean oil was hydrogenated in a 2-L vessel at temperatures ranging from 120 to 170 degrees C at a hydrogen pressure of 200 psi. A commercial nickel-supported catalyst (25% Ni) was used at 0.02% Ni by weight of oil. The hydrogenated oils were characterized for fatty acid composition, solid fat content, and melting point. Compared to commercially processed soybean oil basestocks that typically contain approximately 40% TFA, those obtained at lower temperatures and higher pressures contain >56% less TFA. Basestocks prepared in the laboratory when blended with liquid soybean oil will yield spread oils meeting FDA labeling requirements for zero TFA, that is, <0.5 g of TFA/serving.     

Influence of sulfur fertilization on the amounts of free amino acids in wheat. correlation with baking properties as well as with 3-aminopropionamide and acrylamide generation during baking

Sulfur (S) fertilization has been long-known to influence the amounts of total free amino acids in plants. To determine the impact of S deficiency in wheat on the concentration of, in particular, free asparagine, the spring wheat cultivar 'Star' was grown in a laboratory scale (5 L pot) at five different levels of S fertilization. After maturity, the kernels were milled into white flours (1-5) and analyzed for their contents of total S and total nitrogen as well as for free amino acids and glucose, fructose, maltose, and sucrose. Extremely high concentrations of free asparagine (Asn; 3.9-5.7 g/kg) were determined in flours 1 and 2 (30 and 60 mg of S), whereas much lower amounts (0.03-0.4 g/kg) were present in flours grown at higher S levels. The amounts of the reducing carbohydrates were, however, scarcely affected by S fertilization. In agreement with the high amount of Asn in flours 1 and 2, heating of both flours led to the generation of very high amounts of acrylamide (1.7-3.1 mg/kg) as well as of 3-aminopropionamide (40-76 mg/kg). Similar concentrations were measured in crispbread prepared from both flours. Application of rheological measurements on doughs prepared from each flour and a determination of the loaf volume of bread baked therefrom clearly indicated that flours 1 and 2 would be excluded from commercial bread processing due to their poor technological properties. Two commercial flours showed relatively low concentrations of acrylamide after a thermal treatment.     

封丘地区小麦生产合理灌溉的研究: I.土壤水供给与小麦产量相关性分析

A 5-year experiment on water balance was conducted in a flat rainfed wheat field with an area of 66 m×100 m in Fengqiu, Henan Province, China. Results of the experiment showed that the correlation between wheat yield and water consumption was not significant, but that between wheat yield and the ratio of water supply to Penman evaporation was significant, following a parabolic curve. The water consumption process, as well as the growing season of wheat plant, could be divided into three periods. The first (154 days) was vegetative growth period, during which the water consumption accounted for 35% of the total; the second (65 days) reproductive growth period, during which the water consumption occupied 57%, indicating the importance of water consumption in this period; and the third (5~9 days) maturation period, during which water supply was not important to yield formation. According to the statistics of meteorological data over the years in this region, the hydrological conditions of the five seasons covered a probability range of 74.8%. The results (3.465.63 t ha^-1) indicated that the productivity of the wheat field under rainfed conditions in this region had a degree of confidence of 74.8%.     

Acetonitrile as a buffer additive for free zone capillary electrophoresis separation and characterization of maize (Zeamays L. ) and sorghum (Sorghum bicolor L. Moench) storage proteins

An improved method for separating and characterizing maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) storage proteins by free zone capillary electrophoresis (FZCE) was developed. Previous electrophoretic methods for analyzing these proteins required high concentrations of urea to maintain protein solubility during separation. To overcome disadvantages of urea, we developed a FZCE method that mimicked reversed-phase high-performance liquid chromatography (RP-HPLC) in that it used high levels of acetonitrile (ACN) at low pH. The optimized FZCE buffer system consisted of 80 mM phosphate-glycine buffer, nominal pH 2.5, containing 60% ACN and a cellulose derivative to dynamically coat capillary walls. Resolution was similar to or higher than that previously achieved by FZCE buffers utilizing 8 M urea as a buffer additive. ACN concentrations of at least 50% were necessary to achieve acceptable separations; this ACN concentration is approximately that necessary to extract these storage proteins. ACN was equally effective as traditional ethanol solvents and 8 M urea for solubilizing maize and sorghum proteins. The ACN-based FZCE buffer system gave high repeatability (<0.3% relative standard deviation, measured over 15 consecutive injections) for migration time. Subclasses of maize and sorghum storage proteins were identified, and genotypes of each cereal were successfully differentiated using ACN-containing buffers. This FZCE method may be applicable for the analysis of other hydrophobic proteins without the use of urea.     

Extraction and isolation of lignin for utilization as a standard to determine lignin concentration using the acetyl bromide spectrophotometric method.

Lignin extracted with acidic dioxane was investigated as a possible standard for quantitatively determining lignin content in plant samples using the spectrophotometric method employing acetyl bromide. Acidic dioxane lignins were analyzed for carbohydrate, total protein, nitrobenzene oxidation products, and UV spectral characteristics. Total carbohydrate content of isolated lignins ranged from 2.21 to 5.70%, while protein ranged from 0.95 to 6.06% depending upon the plant source of the original cell wall sample. Nitrobenzene analysis indicated differences in the amount of guaiacyl and syringyl units making up the lignins, but this did not alter the UV spectrum of lignin solubilized in acetyl bromide. Regression equations developed for the acetyl bromide method using the isolated lignins for all the plant samples were similar to each other. Lignin values obtained by the acetyl bromide method were similar to the lignin values obtained as acid insoluble residues following a Klason lignin procedure.     

Suitability of a municipal solid waste as organic amendment for agricultural and metal(loid)-contaminated soils: effects on soil properties,plant growth and metal(loid) allocation in <Emphasis Type="Italic">Zea mays</Emphasis> L.

Purpose

The use of municipal solid wastes (MSWs) as a low-cost source of organic matter for soils should be considered after discarding the environmental risks related to their metal(loid) load. The goal of this work was to assess the employment of a MSW as an organic amendment in two types of soil (an agricultural soil, A, and a metal(loid)-enriched mine tailings soil, T) attending to changes in soil properties and in plant growth, nutrition and metal(loid) translocation from roots to aerial parts of Zea mays L. (stalk, leaves, tassel, husk, cob and kernel).

Materials and methods

After a comprehensive characterisation of each soil treatment (A, A + MSW, T, T + MSW), a pot-designed experiment was carried out. Soil solution was monthly monitored throughout the experiment, and metal(loid) concentrations were measured.

Results and discussion

The MSW improved some fertility-related parameters in both soils, A and T: increased total and dissolved organic carbon, total nitrogen and soil microbiology. However, an increase in 0.01 M CaCl₂-extractable metal(loid) concentration was also observed. No differences in dry biomass were found between amended and not amended treatments. A fractionation of metal(loid) concentrations among plant organs occurred. For instance, the highest Cu and Pb concentrations were found in roots, while for Zn occurred in the stalk and the cob. The amended treatments favoured the accumulation of Mn in all plant organs. Kernels showed in general the lowest metal(loid) concentrations.

Conclusions

The addition of municipal solid wastes as organic amendment could be a suitable tool to increase soil fertility. However, due to the high metal(loid) content of this particular MSW, its use on agricultural soils would not be appropriate. By other hand, along with the improvement of soil fertility, the MSW was useful to promote plant development in the mine tailings soil which should be then considered as a potential tool to promote plant establishment in those metal(loid)-impacted soils.