用二氧化碳提取香料油

无论食品工业还是化妆品工业都需要使用大量的香料油,而同一种香料油的化学成分和感觉特征往往会因提取方法不同而发生变化。目前,人们普遍采用蒸汽蒸馏法,把香料植物材料放在高温高压下蒸馏。用这种方法会导致香料油成分中出现一些矫作物,特别是在水解影响下,更是如此。人们有时也采用低沸点的有机溶剂提取香料油,不过,这又带来另一些问题。例如:提取完成后,需要将有机溶     

不同种植年限有机土基质的变化及其对温室黄瓜生长的影响

研究了不同种植年限有机土基质的理化性质变化及其对黄瓜生长的影响.结果表明：随着种植年限的增加,有机土栽培基质的理化性质变差,表现为容重增大、总孔隙度减小、土壤酸碱度降低、有效养分含量下降;有机土微生物区系中细菌、放线菌数量下降,真菌数量增多.随有机土种植年限的增加,黄瓜的生长受到一定影响,表现为株高、叶面积减小,光合功能衰退,黄瓜产量和品质下降,有必要对连续种植3年的有机土基质进行地力恢复.
     

海南山苍子芳香油分离纯化工艺

利用分子蒸馏技术提纯海南山苍子油,用GC对山苍子里面柠檬醛质量分数和收率进行分析,实验表明获得高纯度、高收率柠檬醛的工业条件是:转数395 rpm,加料速度1.5滴/s,冷却水-5℃,一次分馏温度45℃、压力1 mbar;二次分流温度60℃,压力1 mbar,柠檬醛的质量分数为95.68%,产率为86.60%。     

黔产野生鱼腥草挥发油成分分析

对黔产野生鱼腥草（Ｈｏｕｔｔｕｙｎｉａ ｃｏｒｄａｔａ Ｔｈｕｎｂ）采取水蒸汽蒸馏和石油醚萃取的两种方法提取精油和净油。用ＧＣ／ＭＳ进行定性、定量分析,鉴定了其中４８种成分。比较两种提取方法的分析结果,发现净油中抗菌有效成分鱼腥草素（ｈｏｕｔｔｕｙｎｉｎｕｍ）的含量明显高于精油中的含量。除高沸点的脂肪酸酯外,两者其它化学成分无明显差异。     

有机膜在谷氨酸发酵液分离中的应用研究

目的：采用有机微滤膜和超滤膜连续过滤谷氨酸发酵液,去除菌体蛋白,以利于后续的提取操作。方法：利用微滤膜去除菌体及大分子蛋白等杂质,微滤透过液进入超滤膜系统,进一步去除小分子蛋白及色素等,再利用浓缩连续等电法进行提取,得到谷氨酸。结果：发酵液经过滤后,可溶性蛋白、色素去除率分别可达到86.7%和63.2%,谷氨酸的损失率仅为0.6%;谷氨酸的提取收率和纯度分别可达到95%和99%。结论：利用有机膜系统处理谷氨酸发酵液,可高效去除发酵液中的菌体蛋白和色素等,明显地提高了谷氨酸的提取收率及纯度。     

Zymomonas mobilis用甜菜底物生产酒精的比较

利用在葡萄糖基质培养基上培养Z.mobilis菌生产酒精比酵母有几个优点.其中最重要的是较高酒精收率(超过理论值95%)和较高酒精产率(高出3—5倍).关于用Z.mobilis在蔗糖基质培养基上进行酒精发酵有两个主要问题.首先,由于果聚精和山梨糖醇付产物的形成,酒精收率减小到理论值的70—80%.其次,在象甘蔗糖蜜这样天然底物中Zmobilis的生长和酒精产量都很低.     

酵母制备混合氨基酸的研究

本文报道以单细胞鲜酵母为原料,制备混合氨基酸,具有开拓蛋白质新资源,使之原料来源易,可以工业有机废胶、废糖密等废液来生产醇母,源源不断地供应给生产氨基酸的需要,化废害为利,前途大、效益高,有利于环境保护。同时本实验采用真空加压低酸度水解鲜酵母,以离子交换树脂脱酸制备混合氨基酸的新工艺对此,该工艺生产周期短,设备利用率大,成本低,收率高。     

迷迭香抗氧化剂的提取方法研究

本文介绍了一种两步法从迷迭香植物中提取天然抗氧化剂的方法。先用低沸点有机溶剂进行粗提 ,然后经真空蒸馏去除敏感的色泽和风味物质 ;或用硅胶柱层析分离得到较高纯度的抗氧化剂。将硅胶柱液相色谱层析与真空蒸馏分离得到的抗氧化剂进行抗氧化性能的比较 ,发现后者能获得更高纯度的抗氧化剂。纯化的抗氧化剂组份对植物油和动物油具有显著的抗氧化效能     

水分对有机基质栽培番茄生理特性、品质及产量的影响

以"齐粉"番茄品种为试材,研究了不同相对含水量对有机基质栽培番茄生长、生理特性、产量、品质和水分利用率的影响.结果表明:随着有机基质相对含水量的升高,番茄株高、茎粗、节间长和单株叶面积极显著增加,叶片色素含量、水势、渗透势及根系活力和果实产量显著增加,而番茄果实品质和水分利用率显著降低.从果实产量、品质和水分利用率方面综合考虑,80%基质相对含水量处理的果实产量达26 kg.m-2以上,可作为番茄有机基质栽培水分管理的量化指标;如果仅考虑果实品质,则50%基质相对含水量可以作为水分管理指标.     

分子蒸馏提纯柠檬烯的理论模型研究

为研究刮膜式分子蒸馏过程的数学模型,选用刮膜式短程蒸馏器,采用液氮制冷对橘皮油进行分离。借助传统精馏中的塔板理论和Langmuir-Knudsen等相关理论,对蒸馏过程进行分析,通过物料衡算,建立刮膜式分子蒸馏过程的数学模型,结合模型分析进料速率、蒸馏温度、蒸发面积等因素对产品纯度及收率、理论级数、理论高度的影响,并与实际实验结果对比,二者的偏差不超过11%,验证了模型的合理性,为分子蒸馏器设计的完善提供了一定的理论基础。     

A novel downstream process for highly pure 1,3‐propanediol from an efficient fed‐batch fermentation of raw glycerol by Clostridium pasteurianum

An efficient downstream process without prior desalination was developed for recovering 1,3‐propanediol (1,3‐PDO) with high purity and yield from broth of a highly productive fed‐batch fermentation of raw glycerol by Clostridium pasteurianum. After removal of biomass and proteins by ultrafiltration, and concentration by water evaporation, 1,3‐PDO was directly recovered from the broth by vacuum distillation with continuous addition and regeneration of glycerol as a supporting agent. Inorganic salts in the fermentation broth were crystallized but well suspended by a continuous flow of glycerol during the distillation process, which prevented salt precipitation and decline of heat transfer. On the other hand, ammonium salt of organic acids were liberated as ammonia gas and free organic acids under vacuum heating. The latter ones formed four types of 1,3‐PDO esters of acetic acid and butyric acid, which resulted in yield losses and low purity of 1,3‐PDO (< 80%). In order to improve the efficiency of final 1,3‐PDO rectification, we examined alkaline hydrolysis to eliminate the ester impurities. By the use of 20% (w/w) water and 2% (w/w) sodium hydroxide, > 99% reduction of 1,3‐PDO esters was achieved. This step conveniently provided free 1,3‐PDO and the sodium salt of organic acids from the corresponding esters, which increased the 1,3‐PDO yield by 7% and prevented a renewed formation of esters. After a single stage distillation from the hydrolyzed broth and a followed active carbon treatment, 1,3‐PDO with a purity of 99.63% and an overall recovery yield of 76% was obtained. No wastewater with high‐salt content was produced during the whole downstream process. The results demonstrated that the monitoring and complete elimination of 1,3‐PDO esters are crucial for the efficient separation of highly pure 1,3‐PDO with acceptable yield from fermentation broth of raw glycerol.     

废糟液全循环对自絮凝酵母糖酵解途径关键酶、胁迫相关代谢物及胞内组分的影响

旨在研究废糟液直接全循环对絮凝酵母乙醇发酵、糖酵解关键酶以及细胞组成的影响。在一有效容积1.5 L的搅拌式生物反应器中,使用葡萄糖为220 g/L,添加8 g/L酵母粉和6 g/L蛋白胨的培养基,以0.04 h?1的稀释率进行自絮凝颗粒酵母乙醇连续发酵。每隔3天将收集到的发酵液集中精馏处理,得到的废糟液用于配制发酵培养基。装置运行近20 d,实验结果表明,随着废液循环批次的增加,系统乙醇和生物量浓度明显降低,糖酵解途径3个关键限速酶:己糖激酶、6-磷酸果糖激酶和丙酮酸激酶不同程度受到抑制。为了应对废糟液中高沸点副产物积累导致的环境胁迫,维持细胞正常代谢,甘油和菌体胞内蛋白生物合成加强,碳水化合物积累减弱。这些研究结果对进一步研究高沸点副产物积累对酵母细胞乙醇发酵影响的机理和菌种的代谢工程改造,具有重要意义。     

1,3-丙二醇发酵液后提取技术研究进展

1,3-丙二醇是一种重要的化工原料,以甘油或葡萄糖为原料发酵法制备1,3-丙二醇具有原料可再生、反应条件温和等优点,是近年来国内外的研究热点。由微生物发酵获得的1,3-丙二醇发酵液是含多种强极性的醇及盐类的稀溶液,这使得采用传统的分离方法难以经济、有效地的将1,3-丙二醇从发酵液中纯化出来,后提取过程成为发酵法工业化生产1,3-丙二醇的瓶颈。1,3-丙二醇后提取过程主要包括微生物菌体等高分子物质的去除,盐的去除、回收,有机物的纯化和水的去除。以下对应用于以上分离过程的技术的研究进展进行讨论,提出在该领域应该重视的发展方向。     

Glycerol production by microbial fermentation: a review

Microbial production of glycerol has been known for 150 years, and glycerol was produced commercially during World War I. Glycerol production by microbial synthesis subsequently declined since it was unable to compete with chemical synthesis from petrochemical feedstocks due to the low glycerol yields and the difficulty with extraction and purification of glycerol from broth. As the cost of propylene has increased and its availability has decreased especially in developing countries and as glycerol has become an attractive feedstock for production of various chemicals, glycerol production by fermentation has become more attractive as an alternative route. Substantial overproduction of glycerol by yeast from monosaccharides can be obtained by: (1) forming a complex between acetaldehyde and bisulfite ions thereby retarding ethanol production and restoring the redox balance through glycerol synthesis; (2) growing yeast cultures at pH values near 7 or above; or (3) using osmotolerant yeasts. In recent years, significant improvements have been made in the glycerol production using osmotolerant yeasts on a commercial scale in China. The most outstanding achievements include: (1) isolation of novel osmotolerant yeast strains producing up to 130 g/L glycerol with yields up to 63% and the productivities up to 32 g/(L day); (2) glycerol yields, productivities and concentrations in broth up to 58%, 30 g/(L day) and 110-120 g/L, respectively, in an optimized aerobic fermentation process have been attained on a commercial scale; and (3) a carrier distillation technique with a glycerol distillation efficiency greater than 90% has been developed. As glycerol metabolism has become better understood in yeasts, opportunities will arise to construct novel glycerol overproducing microorganisms by metabolic engineering.     

Highly pure 1,3‐propanediol: Separation and purification from crude glycerol‐based fermentation

A new separation and purification process was developed for recovering 1,3‐propanediol (1,3‐PD) from crude glycerol‐based fermentation broth with high purity. The downstream process integrated chitosan flocculation, activated carbon decolorization, fixed bed cation exchange resin adsorption, and vacuum distillation. Breakthrough curves were measured considering the effect of sample concentration, flow rate, temperature, and resin stack height. Yoon–Nelson model was proposed to fit the fixed bed adsorption. The characteristic column parameters were calculated. Optimal condition for adsorption was 1,3‐PD, 30.0 g/L; flow rate, 1.00 mL/min; stacking height, 30.0 cm; and temperature, 298 K. Ethanol‐water (75%, 1 mL/min) was used as eluent to separate 1,3‐PD and glycerol with 95.3% 1,3‐PD elution rate. After vacuum distillation, the overall purity and yield of 1,3‐PD were 99.2% and 80.8% in the purification process, respectively. This is a simple and efficient downstream strategy for 1,3‐PD purification.     

Recovery of dilute acetone–butanol–ethanol (ABE) solvents from aqueous solutions via membrane distillation

The simultaneous recovery of dilute acetone-butanol-ethanol (ABE) solvents from aqueous solutions by air gap membrane distillation was theoretically assessed. A previously developed and validated Stefan-Maxwell based mathematical model was used for this purpose. It was found that membrane distillation could successfully be used for the recovery of these solvents. Interestingly it was found that butanol could be separated with the highest selectivity and flux though it has the highest boiling point. The effect of operating conditions such as feed and cooling surface temperatures, air gap width, and individual component concentration on the flux and selectivity of these solvents was examined and discussed in this paper.     

By-product inhibition effects on ethanolic fermentation by Saccharomyces cerevisiae

Inhibition by secondary fermentation products may limit the ultimate productivity of new glucose to ethanol fermentation processes. New processes are under development whereby ethanol is selectively removed from the fermenting broth to eliminate ethanol inhibition effects. These processes can concentrate minor secondary products to the point where they become toxic to the yeast. Vacuum fermentation selectively concentrates nonvolatile products in the fermentation broth. Membrane fermentation systems may concentrate large molecules which are sterically blocked from membrane transport. Extractive fermentation systems, employing nonpolar solvents, may concentrate small organic acids. By-product production rates and inhibition levels in continuous fermentation with Saccharomyces cerevisiae have been determined for acetaldehyde, glycerol, formic, lactic, and acetic acids, 1-propanol, 2-methyl-1-butanol, and 2,3-butanediol to assess the potential effects of these by-products on new fermentation processes. Mechanisms are proposed for the various inhibition effects observed.     

Geosmin, an Earthy-Smelling Substance Isolated from Actinomycetes

Geosmin, an earthy-smelling substance, has been isolated from several actinomycetes. Production of 1 mg per liter of whole broth was obtained from Streptomyces griseus LP-16. After preliminary separations, pure geosmin was isolated in milligram amounts by gas chromatography. Geosmin is a neutral oil, with an approximate boiling point of 270 C, which contains carbon and hydrogen, but no nitrogen. It undergoes a reaction with acid to give odorless argosmin, a neutral oil, with an approximate boiling point of 230 C, which contains only carbon and hydrogen. Specific rotation and ultraviolet- and infrared-absorbtion spectra were determined for both.     

Stillage backset and its impact on ethanol fermentation by the flocculating yeast

The second largest cost in fuel ethanol production is from energy consumption with ethanol distillation and stillage treatment, particularly when stillage is treated by the multi-evaporation process. Therefore, stillage backset is the most economically competitive strategy for reducing discharge and saving energy consumption. In this article, continuous ethanol fermentation was performed by the flocculating yeast under stillage backset conditions. Compared to regular yeast, immobilized yeast within the fermentor through flocculation reduced byproducts formation in the stillage, since heat lysis of yeast during ethanol distillation was prevented, and many side reactions were thus eliminated, making more stillage backset within the fermentation system possible. Although pyruvic acid, succinic acid, citric acid, α-ketoglutaric acid, fumaric acid and glycerol from yeast metabolism, furfural and 5-hydroxymethyl furfural from process operations, and acetic acid and lactic acid from slight contamination were accumulated with the stillage backset, they had no significant impact on yeast growth and ethanol fermentation due to low concentrations accumulated within the fermentation system. However, propionic acid that was generated mainly during hydrolysate sterilization and distillation of the fermentation broth was detected as the major inhibitor, but this byproduct would be significantly reduced under industrial conditions without hydrolysate sterilization, making the stillage backset more reliable for industrial application.     

Efficient recovery of gamma-poly (glutamic acid) from highly viscous culture broth.

An efficient strategy for the separation and recovery of gamma-polyglutamic acid (gamma-PGA) from highly viscous broth was developed. This strategy was divided into two processes: The first was to separate gamma-PGA from highly viscous culture broth; the second was to concentrate gamma-PGA solution by ultrafiltration for the reduction of the amount of alcohol required during recovery process with precipitation. By lowering the pH value of culture broth to 3, the viscosity of culture broth and the zeta potential of cell could be reduced to a sixth of the original value at 35 degrees C and a third, respectively. After the acidification of culture broth the energy demand for the separation of gamma-PGA from culture broth by centrifugation could be reduced to 17% of that without it when the centrifugal force was 22,000g. The amount of alcohol required for precipitation could be reduced to a fourth of that generally used without concentration by concentrating 20 g gamma-PGA/L solution to 60 g gamma-PGA/L at pH 5 by ultrafiltration with hollow-fiber membrane cartridge (MWCO 500,000).