有机溶剂的冷冻干燥研究

介绍了非水有机溶剂的特点及其在冷冻干燥中的应用,重点论述了叔丁醇的冷冻干燥特性。      

1,2-二氯乙烷冷冻干燥工艺的研究

1,2-二氯乙烷是一种常用的有机溶剂,在很多工业生产中作为溶剂时可重复使用,但在一些要求无水条件下进行反应的生产中,需对其回收后进行干燥,达到要求后方可使用.文章对二氯乙烷回收采用的冷冻干燥工艺进行研究.     

芫荽真空冷冻干燥的研究

本文采用真空冷冻干燥技术,探讨了搁板温度、物料重量对芫荽冻干时间、品质及设备生产能力的影响。试验结果表明,搁板设置温度每提高10℃,冻干时间缩短15.68%以上,但温度过高芫荽风味下降,出现干草味;芫荽每增加100g/层,冻干时间延长2.5～3h左右。在温度40℃、芫荽重量400g/层条件下冷冻干燥,冻干时间为12.5h,产品质量优于单纯的真空干燥样品;复水后与新鲜芫荽相对较为接近。     

牦牛肉冷冻干燥过程的研究

研究了牦牛肉的冻干过程 ,得到了牦牛肉的共熔点、冻干曲线及其传热传质特性。探讨了牦牛肉在冻干过程中系统压力及其物料厚度对冻干速率的影响 ,确定了解析阶段循环调压的方法以及物料的最佳冻干厚度     

草菇冷冻干燥保鲜技术的研究

介绍了草菇冷冻干燥保鲜工艺及其工艺参数，并着重对水份升华过程中的供热方式进行了探讨。分析了新鲜草菇和冻干草菇的氨基酸含量，认为冷冻干燥是草菇保鲜贮藏的一种较理想的方法。     

真空冷冻干燥食品

介绍了冷冻干燥技术的原理、特点、冷冻干燥食品简要的生产工艺流程及发展现状。     

鼠曲草真空冷冻干燥的实验研究

对鼠曲草真空冷冻干燥进行了实验研究,并用热风干燥、真空干燥、微波干燥进行对照。实验结果表明,采用真空冷冻干燥鼠曲草,可以更好地保持鼠曲草的色泽、形态及营养成分,较其它干燥方法更佳。      

鼠曲草真空冷冻干燥的实验研究

对鼠曲草真空冷冻干燥进行了实验研究,并用热风干燥、真空干燥、微波干燥进行对照。实验结果表明,采用真空冷冻干燥鼠曲草,可以更好地保持鼠曲草的色泽、形态及营养成分,较其它干燥方法更佳。     

荔枝真空冷冻干燥实验研究

用真空冷冻干燥技术加工荔枝干,可以最大限度保持其形状、色、香、味及营养成分,比之传统荔枝干加工方法（日晒法和火焙法）有很多优点,值得推广。     

草莓冷冻干燥工艺研究

以长丰草莓(品种为天香)为对象,对整粒草莓的真空冷冻干燥技术进行研究。以复水比为指标,考察了草莓预冻工艺和真空冷冻干燥工艺中影响产品质量的主要因素,通过正交试验对草莓的冷冻干燥工艺进行优化,确定了适合工业化生产的工艺参数。研究结果如下:试验所用草莓的共晶点为-15℃;最佳预冻条件是:在-25℃中冷冻2.5 h;真空冷冻干燥工艺可分为四个阶段:第一阶段在-25℃干燥10 h,第二阶段在-5℃干燥10 h,第三阶段在15℃干燥12 h,第四阶段在40℃干燥8h,此时工艺最佳。     

Stability of immobilized thermolysin in organic solvents

Various factors affecting the stability of thermolysin immobilized by cross-linking with glutaraldehyde were elucidated, particularly in the water-immiscible organic solvents such as ethyl acetate and tert-amyl alcohol. The main reason for enzyme inactivation in water-immiscible organic solvents was found to be autolysis in the water phase, which may surround the enzyme immobilized inside the support. By contrast, in water-miscible organic solvents thermal denaturation was the predominant cause of enzyme inactivation. Courses of inactivation were expressed by second-order kinetics in the initial stage, after which inactivation proceeded at a slower rate. The extent of autolysis was found to strongly depend on the kind of organic solvent, the water content, and type of support and these dependencies were explained by the difference in the amount and state of water inside the support. Thermolysin was immobilized onto Amberlite XAD-7 as a compact aggregate inside the support which may increase the stability of the enzyme. Finally, it was shown that the stability of the immobilized enzyme could be correlated with the logP value for water-miscible organic solvents and with the solubility of water for water-immiscible organic solvents.     

Biocatalytic production of chiral epichlorohydrin in organic solvents

Enantioselective hydrolysis of racemic epichlorohydrin was accomplished for the production of enantiopure epichlorohydrin using the whole cells of an isolated Aspergillus niger spps. To overcome the spontaneous chemical degradation of epichlorohydrin that occurs in aqueous buffer, organic solvents were employed in the reaction medium. The enantioselectivity was highly dependent on the solvent structure, water content of the medium, and the initial epichlorohydrin concentration. (S)-epichlorohydrin could be obtained from its racemates (60 mM) with an optical purity of 100% enantiomeric excess (ee) and 20% yield in cyclohexane supplemented with 2.0% (v/v) water.     

有机相脂肪酶催化合成肉桂酸肉桂酯的研究

肉桂酸肉桂酯是一种重要的花香型香精定香剂。本实验对有机相中脂肪酶催化合成肉桂酸肉桂酯进行研究,对酶催化条件进行了优化研究。实验结果表明:Candida anatarctic脂肪酶(Novozyme 435)有较好的催化活性。通过单因素实验考察各反应参数(反应溶剂、温度、底物摩尔比、底物浓度等)对脂肪酶Novozyme 435合成肉桂酸肉桂酯反应的影响,确定了反应最优工艺条件:在5 mL甲基叔丁基醚溶剂(分子筛脱水)体系中,肉桂醇100 mmol/L,n(肉桂醇):n(肉桂酸乙酯)=2:1,反应温度50℃,Novozyme 435脂肪酶添加量1%(质量体积比),反应36 h后反应转化率可达到55%,产物结构经气相质谱(GC/MS)鉴定。     

气质联用法测定REACH法规中的5种有机溶剂

建立了气相色谱-质谱联用技术测定REACH法规中列举的乙二醇单甲醚、乙二醇单乙醚、乙二醇乙醚乙酸酯、1,2,3-三氯丙烷和N-甲基吡咯烷酮等5种高度关注物质的方法,并对色谱条件和样品前处理条件进行了优化:以丙酮为提取溶剂,超声提取,0.45μm有机相微孔滤膜过滤.在本试验研究范围内,标准工作曲线溶液呈良好的线性关系,相关系数均大于0.994.该方法简便、准确、灵敏度高,回收率较高,相对标准偏差小于10％,检测限远低于REACH法规0.1％的限量要求.     

Expression of Rhodococcus opacus alkB genes in anhydrous organic solvents

Rhodococcus opacus B-4 is a benzene-tolerant bacterium which was isolated from a gasoline-contaminated soil sample. We previously demonstrated that this organism was able to survive and exhibit biocatalytic activity in anhydrous organic solvents for at least 5 d. In the present study, we cloned the alkB1 and alkB2 genes encoding alkane hydroxylases from R. opacus B-4. Heterologous expression of the alkB1 and alkB2 genes in Escherichia coli JM109 showed that they encode functional alkane hydroxylases with a substrate range of C(5)-C(16). Promoters of the alkB1 and alkB2 genes, designated P(alkB1) and P(alkB2), respectively, were examined for activity in anhydrous bis (2-ethylhexyl) phthalate (BEHP) containing C(5)-C(16)n-alkanes. Two recombinant plasmids, pP(alkB1)EGFP and pP(alkB2)EGFP, were constructed by inserting the egfp gene downstream of P(alkB1) and P(alkB2), respectively and transformed into R. opacus B-4. Resting cells of R. opacus B-4 (pP(alkB1)EGFP) showed greater levels of EGFP fluorescence in anhydrous BEHP than in 0.85% NaCl, when C(8)-C(16)n-alkanes were supplied as an inducer. Furthermore, n-alkane inducibility of P(alkB1) activity in anhydrous BEHP was noticeably different from that in 0.85% NaCl. This paper presents the first evidence that bacteria can express their genes in essentially anhydrous organic solvents.     

溶解状态下番茄红素稳定性研究

研究了溶解状态下番茄红素在不同条件下存放时被氧化破坏或发生顺反异构化的规律，依据SAS软件的处理结果给出了其残留率计算公式并提出了适宜的产品存放条件。     

Enzymes which are stable in the presence of organic solvents

There are numerous advantages of employing enzymes as catalysts in organic solvents or aqueous solutions containing organic solvents instead of water. A few natural enzymes which are stable in the presence of organic solvents have been discovered. However, almost all natural enzymes are easily denatured and inactivated in the presence of organic solvents. Therefore, several physical and chemical methods, such as immobilization, modification, and entrapment, for stabilizing enzymes in the presence of organic solvents were developed. Protein engineering using site directed mutagenesis and directed evolution are useful for clarifying why organic solvent-stable enzymes are stable in the presence of organic solvents and for developing organic solvent-stable mutant enzymes.     

Enzymatic synthesis of sugar amino acid esters in organic solvents

The enzymatic synthesis of sugar amino acid esters in polar organic solvents was studied using surfactant-enzyme complexes, which were previously developed as a highly active biocatalyst in organic solvents. Of the several lipases and proteases tested, the surfactant-subtilisin complex exhibited the highest synthetic activity in pyridine. The amino acid was regioselectively introduced at the C-6 position of d-glucose and at the C-6' of maltose by the surfactant-subtilisin complex. This biocatalyst was found to effectively catalyze the synthesis of various sugar amino acid esters in a polar organic solvent.     

Toxicity of ionic liquids and organic solvents to lactic acid-producing bacteria

In situ extractive fermentation of lactic acid using organic solvents has already been extensively investigated. Now ionic liquids are emerging as alternative solvents for volatile organic compounds traditionally used in liquid-liquid extraction. In this study, we examine whether lactic acid producing-bacteria can grow in the presence of a second phase of imidazolium-based ionic liquids or organic solvents. The lactic acid producing-bacteria used in this study are sensitive to organic solvents having 1 < log P < 4. We found that Lactobacillus delbruekii subsp. lactis NRIC 1683 could grow in the presence of a second phase of imidazolium-based ionic liquids as well as in the absence of the ionic liquids.