石榴气调保鲜效果研究

院本文研究了气调保鲜技术对贮藏期间石榴品质的影响。结果发现,在2益低温条件下,4%O2协同5%CO2,贮藏140d时,石榴的呼吸强度为22.01mgCO2/（kg·h）,褐变指数为0.16,可溶性固形物及总酸含量分别为14.7%与0.41%,可以较好地维持石榴的品质与口感。该处理石榴MDA含量累积最少,对PPO活性及果实腐烂抑制作用最强。     

再生水灌溉对天津滨海盐碱地绿地土壤的影响

对天津诺维信公司排放出的再生水进行化学评价,确定其水质为重盐碱水,试验中配成的混水水质介于中等水与盐碱水之间.用这两种水分别浇灌天津滨海盐碱绿地土壤,土壤中ESP、SAR、Cl-均比淡水灌溉土壤有显著提升;再生水浇灌的土壤已接近轻度碱化土,且有加深的趋势;混水灌溉土壤较好,但长期灌溉后,也有轻微碱化的趋势.不同植物对再生水浇灌后的反应不同,其中国槐、草坪草耐性较强,暂时不造成危害.用磷石膏修复再生水后,处理水的化学指标达到灌溉水质标准.对于再生水对土壤和植物的影响需注意监测并采取措施进行预防.     

蒜薹灰霉病菌的生物学特性研究

对已分离的蒜薹灰霉菌的生物学特性进行测定,结果表明:蒜薹灰霉菌对碳源的利用以果糖、葡萄糖为最佳;生长的温度范围为5~30℃,最适为25℃;光暗交替对菌落生长有促进作用;生长的适宜pH值为2.5~12.5,最适为6。该菌在葡萄糖中最宜产孢;产孢的适宜温度是10~28℃,最适为20℃;光暗交替对灰霉菌产孢有促进作用;产孢初始适宜pH值为3.5~12.5,最适为6。     

适量卵磷脂改善低酯苹果果胶凝胶流变性

为了进一步了解卵磷脂在果胶凝胶中的作用,该文考察卵磷脂对果胶凝胶流变性的影响,以低酯苹果果胶为原料,在钙离子浓度为12 mmol/L条件下,加入质量分数0.2%~1.2%的卵磷脂,考察凝胶过程中储能模量(G′)与损耗模量(G″)变化。通过凝胶结构形成速度(structure developing rate,SDR)流变学分析方法探讨在果胶凝胶过程中卵磷脂对凝胶体系的影响,结果显示:卵磷脂的添加对果胶钙凝胶的形成速度(SDR)和储能模量(G′)有影响,在整个温度变化范围内,卵磷脂添加量小于0.4%时对SDR曲线和G′曲线的影响不明显;卵磷脂添加量为0.4%时SDR曲线和G′曲线明显上升,显示出较快的凝胶速度和较强的凝胶强度;当卵磷脂添加量大于0.4%时,SDR曲线和G′曲线下降。凝胶形成动力学研究显示,加入0.4%的卵磷脂,使果胶的凝胶过程在高温区和低温区的差别更大,活化能差别也较大(P0.05):高温区活化能为290.6 k J/mol,低温区活化能为67.1 k J/mol。电镜扫描显示添加0.4%卵磷脂的果胶钙凝胶结构更为均匀紧密。研究结果为卵磷脂/果胶体系的应用提供理论参考数据。     

电场处理改善玉米醇溶蛋白膜理化性质

传统浇铸法制备的玉米醇溶蛋白薄膜表面粗糙,机械性质及耐水性较差。为了改善玉米醇溶蛋白理化性质,在传统浇铸法膜制备过程中引入平行匀强电场(1~5 A/m2)处理蛋白成膜液。经过电场处理后,玉米醇溶蛋白表面光滑、形状完整。试验结果表明:电场处理可改善薄膜力学性质、表面疏水性、水蒸气透过率等性质;随着电流密度的增大,薄膜拉伸强度、断裂伸长率、水蒸气透过率、吸水率以及表面接触角呈现规律性增加或者减小;电场处理下薄膜热特性改变,与未处理组相比变性温度略有提高,最大增幅为19.5℃。当电流密度为4 A/m2时,薄膜理化性质较佳:拉伸强度、断裂伸长率分别为73.09 MPa和9.68%,吸水率降低至14.87%,水蒸气透过率为2.55×10-8 g·m/(m2·h·Pa),静态接触角为62.18°,变性温度提高到118.39℃,热稳定性提高,薄膜表面光滑。电场可诱导成膜液中分子有序性排列,提高薄膜均一性;通过调节电流密度可得到具有一定力学强度和亲/疏水性的薄膜。试验结果为制备具有特定功能性的纯玉米醇溶蛋白薄膜材料提供了理论依据。     

Antioxidant properties and structural analysis of phenolic glucosides from bark of <Emphasis Type="Italic">Populus ussuriensis</Emphasis> Kom.

The methanol (MeOH) extract of Populus ussuriensis Kom. bark was analyzed for antioxidant assessing by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging potential. Among fractions using several solvents, the ethyl acetate (EtOAc) soluble fraction, which showed strong antioxidant activity (IC₅₀ 2.02 ± 0.01 μg/ml), was further purified by Thin layer chromatography (TLC) guided Sephadex LH-20 column chromatography. Three known phenolic glucosides, picein (I), salicortin (II), grandidentatin (III), and that of a new, 2-hydroxycyclohexyl-4′-O-p-coumaroyl-β-d-glucopyranoside (isograndidentatin A), were isolated and their structures were elucidated on the basis of physiochemical and spectroscopic methods. This was the first report of the chemical composition of P. ussuriensis bark. Phenolic glucosides III and IV exhibited strong antioxidant activities, with IC₅₀ values 6.73 ± 0.01 and 6.69 ± 0.01 μM, respectively, comparable to the control (α-tocopherol, IC₅₀ 6.80 ± 0.01 μM). P. ussuriensis bark EtOAc-soluble fraction and compounds III and IV could be used as biopreservatives in food applications as well as for cosmetic and medicinal preparations, to alleviate oxidative stress.     

基于自编码神经网络建立的搜索信息模型

根据用户搜索历史,将用户关注的信息按标题分类,通过自编码神经网络提取特征值。设定学习样本标题最多为25个汉字,编码方式采用汉字机内码(GBK码)。使用MATLAB工具进行深度学习,将样本在原空间的特征表示变换到一个新的特征空间。     

稻壳灰制备聚硅酸硫酸铝絮凝剂及其结构性能

为了进一步充分利用稻壳灰中的硅和碳,该文提出由稻壳灰制备水玻璃并进一步制备聚硅酸硫酸铝(poly aluminum silicate sulfate,PASS)絮凝剂,对PASS进行结构表征,并考察了PASS处理有机废水的絮凝效果。结果表明,由稻壳灰制备水玻璃,可通过碱处理稻壳灰获得模数为3.3的水玻璃并联产活性炭;再由上述水玻璃制备PASS。通过考察二氧化硅质量分数、铝硅摩尔比、p H值对其絮凝性能的影响,得到较佳工艺条件:二氧化硅质量分数7%,铝硅摩尔比1∶2,p H值为2.0,此条件下投量(以Al2O3计)60 mg/L时有机废水(油墨废水)的除浊率和脱色率分别为97.29%、94.26%,相同投量下处理有机废水(油墨废水和油脂废水),PASS的除浊率和脱色率高于聚合氯化铝(poly aluminum chloride)10%~20%左右;X射线衍射(x-ray diffraction)、傅里叶红外光谱(Fourier transform infrared spectrometer)的结构分析表明PASS是由硅和铝组成的无定型聚合物。研究结果为稻壳灰资源的应用开辟一条新途径,为絮凝剂的原料来源提供参考。     

Molecularly imprinted polymer online solid-phase extraction coupled with high-performance liquid chromatography-UV for the determination of three sulfonamides in pork and chicken

A selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique with a sol-gel process for online solid-phase extraction-HPLC determination of three trace sulfonamides in pork and chicken muscle. The imprinted functionalized silica gel sorbent exhibited selectivity and fast kinetics for the adsorption and desorption of sulfonamides. With a sample loading flow rate of 4 mL min (-1) for 12.5 min, enhancement factors and detection limits for three sulfonamides ( S/ N = 3) were achieved. The precision (RSD) for nine replicate online sorbent extractions of 5 microg L (-1) sulfonamides was less than 4.5%. The sorbent also offered good linearity ( r (2) > 0.99) for online solid-phase extraction of trace levels of sulfonamides. The method was applied to the determination of sulfonamides in pork and chicken muscle samples. The prepared polymer sorbent shows promise for online solid-phase extraction for HPLC determination of trace levels of sulfonamides in pork and chicken samples.     

Development of a capillary electrophoresis-based immunoassay with laser-induced fluorescence for the detection of carbaryl in rice samples

A capillary electrophoresis-based competitive immunoassay (CEIA) with a laser-induced fluorescence (LIF) detector for the determination of carbaryl was developed. The method was based on the competitive reactions between fluorescently labeled carbaryl tracer (Ag*) and free carbaryl (Ag) with a limited amount of anticarbaryl antibody (Ab), and the relative amounts of each were separated and determined by capillary electrophoresis (CE) with an LIF detector. Using CEIA, equilibrium was reached in 30 min, and the analytical results were obtained within a further 8 min. The linear range and the detection limit for carbaryl were 0.16-50 ng/mL and 0.05 ng/mL, respectively. The sensitivity of this CEIA with an LIF detector was almost 14 times greater than that of ELISA, which used the same immuno-reagents. The method was also applied to the analysis of carbaryl in rice with rapid and simple sample pretreatment. The method is thus proposed as a fast and sensitive assay for the detection of carbaryl.