共查询到19条相似文献,搜索用时 296 毫秒
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以玉米粉作为吸附剂制备了无水乙醇.研究了制备过程中的影响因素如吸附剂粒度、用量、加热功率及吸附床夹套温度等对产品中乙醇质量分数的影响.研究结果表明玉米粉作为吸附剂制备无水乙醇的工艺是可行的.在吸附剂粒度为40~60目,吸附剂用量为50g,加热套加热功率为70~80W,吸附床夹套温度选用80~85℃的条件下,可制得质量分数大于99.2%的无水乙醇. 相似文献
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通过对小麦粉脂肪酸值三种测定方法的比较,优化游离脂肪酸提取方法和滴定体系,建立一种测定结果准确、可靠,测定过程环保、安全,又不破坏现行小麦粉脂肪酸值评价体系的小麦粉脂肪酸值测定方法。研究结果表明,无水乙醇提取法测定小麦粉脂肪酸值与苯提取法测定小麦粉脂肪酸值相比,方法的准确性和重复性无显著性差异,可以替代苯提取法测定小麦粉脂肪酸值。该方法不使用有毒有害试剂,有利于保护环境和操作人员身体健康;滴定终点易于观察判定,测定的精密性好;与稻谷、玉米等现行脂肪酸值测定方法测定过程一致,有利于实现粮食脂肪酸值测定方法的优化、整合。 相似文献
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Nicolas Verhoeven Tze Loon Neoh Takeshi Furuta Chisho Yamamoto Tetsuya Ohashi Hidefumi Yoshii 《Food chemistry》2012
Dehydration of dihydrate trehalose to its anhydrous form was performed via crystal transformation in a pressure pan with a differential scanning calorimeter using ethanol as the drying medium. The effect of water content of ethanol on the dehydration kinetics was investigated by differential scanning calorimetry (DSC), under two experimental conditions: isothermal and temperature ramping. The data sets collected were analysed by the Avrami equation and the Arrhenius plots for isothermal conditions and by Kissinger’s method for non-isothermal measurements. The Kissinger plots revealed click point temperatures (CPTs) which were dependent on the water content of ethanol. At temperatures below the CPTs, higher activation energies were found, whereas at temperatures above the CPTs, lower activation energies were estimated. The anhydrous trehalose crystals obtained by crystal transformation using ethanol of 0.005–2.5% water content were visually observed as aggregates of nano-sized acicular crystals, which inherited the shapes of the dihydrate trehalose crystals. 相似文献
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目的:在“成分-功效”关联模式下,探究补骨脂四种不同浓度乙醇提取物主要活性成分含量、抗氧化及胆酸盐结合能力差异。方法:以补骨脂为原料,采用无水乙醇、75%乙醇、50%乙醇、水进行提取,比较其总黄酮和总多酚含量,并分别通过3种抗氧化体系与胆酸盐结合能力进行体外抗氧化和降脂活性评价,并进行相关性分析。结果:无水乙醇提取物总黄酮含量(50.317±0.018 mg/g)和总多酚含量(3.860±0.045 mg/g)最高。补骨脂50%乙醇提取物对ABTS+·和DPPH·清除能力最强,IC50值分别为0.76和1.63 mg/mL,无水乙醇提取物还原能力最强,A0.5值为2.63 mg/mL。补骨脂水提物对胆酸钠的结合能力最强,IC50值为0.67 mg/mL,而50%乙醇提取物对牛磺胆酸钠和甘胺胆酸钠结合能力最强,IC50值分别为1.26和0.41 mg/mL。相关性结果表明,补骨脂不同浓度乙醇提取物中总黄酮含量与DPPH·清除率、牛磺胆酸钠结合率呈显著正相关性(P<0.05),总黄酮、总多酚含量与还原能力均呈极显著性正相关关系(P<0.01),而总多酚含量与胆酸钠结合率呈显著性负相关性(P<0.05)。结论:补骨脂50%乙醇提取物活性含量较高,抗氧化及结合胆酸盐能力最强,可以作为潜在的天然抗氧化及降脂活性物质的重要来源。 相似文献
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Jin Li-E Cao Qing & Xie Ke-Chang 《International Journal of Food Science & Technology》2008,43(4):666-672
The extract yields obtained by three methods in different solvents from chilli were compared. The antioxidant activities of chilli extracts vs. butylated hydroxytoluene (BHT) was determined through the peroxide value (POV), the beta‐carotene bleaching assay and the 2,2‐diphenyl‐1‐picrylhydrazyl radical scavenging method. The results showed that the extract yields by three extract methods, namely, Soxhlet, ultrasonic wave and saturation, were 16.32%, 15.78% and 11.62%, respectively, when 85% ethanol acted as solvent. The extracting efficiency of solvent from high to low was 95% ethanol > ethyl acetate > anhydrous ethanol > distilled water. The total phenol content of chilli extracts from ultrasonic wave with 85% ethanol as solvent was 73.91 mg gallic acid equivalents (GAE) per gram extracts and the value of inhibitory capacity IC50 on free radical (DPPH) was 38.99 mg mL?1. The POV of chilli extracts was close to that of BHT. The ultrasonic wave was more helpful for the extraction of antioxidant substance from chilli than other methods. In addition, the composition of chilli extracts was analysed by gas chromatography‐mass spectrum (GC‐MS). 相似文献
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玉米秸秆经过预处理、酶水解、发酵可生产燃料乙醇,但其自身具有的木质纤维素紧密结构使得酶水解效率很低,导致乙醇产量低。因此,采用适当的方法对玉米秸秆进行预处理,破坏秸秆原有的纤维结构,提高酶水解效率和可利用性。本文对当前国内外玉米秸秆各种预处理最新方法进行了综述,同时对每种预处理方法的优缺点进行了分析,为玉米秸秆发酵生产燃料乙醇预处理方式的选择提供参考。 相似文献
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以蒸馏水、无水乙醇为溶剂结合超声波辅助及传统煎煮方法对艾叶进行提取,测定各提取物总黄酮和总酚含量、自由基清除能力以及艾叶提取物对黄嘌呤氧化酶(Xanthine Oxidase,XOD)的抑制作用,并选取抑制效果较好的艾叶醇提物,利用动物实验,测定小鼠血清尿酸(UA),肌酐(Scr),尿素氮水平(BUN),肝脏XOD活性,研究艾叶提取物对高尿酸血症小鼠的降尿酸的作用。结果表明:总黄酮和总酚含量:醇提物传统法提取物水提物,清除自由基能力和抑制XOD作用:醇提物传统法提取物水提物,三种提取物对XOD的抑制作用均表现为不可逆抑制,其中传统法和醇提物对XOD的抑制类型为反竞争性抑制,水提物为混合性竞争性抑制;传统法和水提物与别嘌呤醇联合抑制作用表现为相加作用,醇提物表现为弱协同作用;艾叶醇提物对高尿酸血症小鼠的UA,Scr,BUN水平均具有降低效果,对肝脏XOD活性具有抑制作用。结论:艾叶各提取物具有较好的抑制黄嘌呤氧化酶和抗氧化作用,醇提物具有开发成为预防和治疗高尿酸血症药物的潜力。 相似文献