以纤维素类物质为原料发酵生产燃料乙醇的研究进展

燃料乙醇是清洁汽油的主要代替物。其生产方法根据原料区分有 :糖蜜类、谷物淀粉类和纤维素类。以植物秸秆、木材等纤维素类物质为原料生产乙醇是最具挑战性的课题 ,目前用纤维素类物质制造乙醇的关键问题是纤维素原料的预处理和高效的发酵工艺。文中就综述了纤维素类物质的发酵机制、发酵工艺和发酵方式 ,对进一步实现工业化提供一些借鉴。     

木质纤维素原料预处理技术研究进展

纤维素原料的预处理是木质纤维素转化乙醇过程中的关键步骤,其直接影响着纤维素的水解效率和纤维素产生乙醇的生产成本.对各种纤维素原料预处理方法进行了简要综述,并对各种方法的优缺点进行了分析和讨论,最后对生物质预处理技术发展的前景进行了展望.     

纤维素乙醇生产中的预处理技术

当前,寻求可再生的清洁能源成为全球亟待解决的问题。纤维素原料十分丰富,又是可再生资源,利用纤维素制备纤维素燃料乙醇是发展新能源的重要途径,具有巨大的潜力和可再生性。纤维素原料的预处理是其转化乙醇过程中的关键步骤,直接影响着纤维素的水解效率和纤维素产生乙醇的生产成本。本文简要综述了各种纤维素原料预处理方法,并对各种方法的优缺点进行了分析和讨论。     

利用纤维素原料生产燃料酒精的研究进展

介绍了近年来美、日两国关于纤维素制乙醇技术的发展情况。燃料乙醇的应用意义及现状。综述了纤维素原料生产乙醇的预处理及水解为葡萄糖技术的研究进展 ,介绍了纤维素原料发酵生产酒精技术的概况 ,对不同的预处理、水解和发酵方法进行了比较     

木质纤维素糖化前预处理新技术研究进展

木质纤维素的糖化前预处理是生产燃料乙醇过程中最基础最关键的一步,影响整个纤维素酒精生产过程.该文对木质纤维素的糖化前预处理新技术进行了分析和讨论,并对其前景进行了展望.     

基于酶水解的高效生物质乙醇生产过程的预处理技术

介绍了利用木质纤维原料生产乙醇的主要技术,并指出技术先进、低成本的预处理工艺所需达到的关键指标。与用淀粉或糖类生产生物质乙醇相比,用木质纤维原料生产生物质燃料（即第二代生物质乙醇）具有经济和环境方面的优势,但由于木质纤维原料主要组分较为紧密,阻碍了纤维素和半纤维素水解为可发酵糖的进程。预处理的主要目的是提高酶的可及性,从而提高纤维素降解率。每种预处理方法对纤维素、半纤维素和木素都有特定的影响,应根据后续水解和发酵工艺来确定预处理方法和条件。     

关于纤维素酒精生产预处理方法的探讨

木质纤维素原料的预处理是纤维素转化乙醇过程中的关键步骤,其直接影响着纤维素的水解效率和纤维素产生乙醇的生产成本。大量试验研究证明,以秸秆为原料生产纤维素酒精的预处理过程,采用蒸汽爆破法要比稀酸水解法更有优势,更容易实现工业放大。     

木质纤维素预处理技术研究进展

纤维质物料的预处理是木质纤维素原料生产燃料乙醇的关键步骤.介绍了木质纤维素物科的组成和结构及其对纤维素水解的影响,从经济角度总结了预处理的目的和评判预处理效果的标准.概述了常用的预处理方法,讨论了几种极具经济潜力的预处理技术,对预处理技术的发展前景进行了展望.     

木质纤维素的物理预处理技术

纤维素是地球上最丰富的可再生资源,预处理技术是实现木质纤维素转化乙醇的关键步骤。总结了近年来的纤维素物理预处理技术及物理结合其他技术预处理技术,展望了木质纤维素物理预处理方法的发展前景。     

纤维素类物质生产乙醇研究进展

纤维素类物质是可再生资源,资源丰富,利用纤维素类物质制备燃料乙醇是发展新能源重要途径。该文综述利用纤维素类物质生产乙醇研究进展,重点介绍预处理、糖化、发酵等工序。     

生物技术应用于造纸法再造烟叶生产的研究进展

生物技术应用于再造烟叶生产有着广阔的发展空间。本文从微生物发酵技术和酶技术两个方面综述了生物技术在造纸法再造烟叶生产中应用的研究情况。首先,介绍了微生物发酵技术在原料预处理和烟草萃取物处理中的应用;其次,介绍了酶技术在原料预处理、烟草萃取工序、烟草萃取液及涂布工艺中的应用,最后对上述技术在再造烟叶中的应用研究进行了展望,以期为应用生物技术方法提高再造烟叶品质提供理论依据。     

利用皮状丝孢酵母对甘蔗渣酶解液产油脂的研究

本试验旨在研究碱和高温液态水2种预处理方式对发酵的影响。甘蔗渣分别利用碱和高温液态水(LHW)预处理,然后使用纤维素酶进行酶解。在LHW和碱预处理后的酶解液中,分别含22.06和39.28 g/L总糖。不经过浓缩,也不需要添加任何营养物质,酶解液被用于皮状丝孢酵母的油脂发酵试验。经过3 d的培养,在LHW预处理的酶解液中,皮状丝孢酵母的生物量达到了8.08 g/L,油脂质量分数为52.00%,油脂系数高达19.03%。在碱预处理的酶解液中,经过8 d的培养,皮状丝孢酵母的生物量为13.67 g/L,油脂质量分数为43.20%,油脂系数为15.03%。脂肪酸组成分析表明所产油脂与棕榈油的组成相似。试验结果表明,甘蔗渣是一种有前景的产油脂原料,LHW是一种良好的预处理方式。该研究为利用甘蔗渣发酵产油脂提供了新思路。     

浅谈提高甘蔗破碎效果的措施

在生产中如何在有限的甘蔗资源中提高糖分的收回率是各糖厂挖潜技术改造设备的关键所在。压榨提汁工段中提高压榨抽出率是一种有效的手段,其中提高甘蔗的破碎效果是提高生产规模和压榨抽出率的重要措施。现大多数糖厂使用的甘蔗预处理设备为转鼓式蔗刀机(切撕机),通过2~3台切撕机的组合,甘蔗破碎度普遍达到70%以上,如果对甘蔗预处理环节进行技术改造,甘蔗破碎度可达到85%~90%。本文从影响甘蔗破碎效果的主要环节讨论提高甘蔗破碎效果的措施。     

Effect of ozone pretreatment on fish storage life at low temperatures

The purpose of the present study was to determine the effect of ozone pretreatment of live fish on their shelf life and storage characteristics during storage at 0 and 5 degrees C. The evaluation included sensory, chemical, physical, and bacteriological tests at set intervals throughout a storage period of 30 days under two temperature regimes (0 and 5 degrees C). The results of the sensory tests showed that ozone pretreatment of live tilapia prolonged their shelf life by 12 days and improved their quality characteristics during storage at 0 degrees C for 30 days. These results were corroborated by the bacteriological tests. The sensory qualities of ozone-treated tilapia stored at 5 degrees C became unacceptable 3 days later than those of control fish. Although the most important factor affecting the fish shelf life is storage temperature, the combination of ozone pretreatment with storage at 0 degrees C appears to be a promising means of prolonging the shelf life.     

Bioethanol production from ball milled bagasse using an on-site produced fungal enzyme cocktail and xylose-fermenting Pichia stipitis

Sugarcane bagasse is one of the most promising agricultural by-products for conversion to biofuels. Here, ethanol fermentation from bagasse has been achieved using an integrated process combining mechanical pretreatment by ball milling, with enzymatic hydrolysis and fermentation. Ball milling for 2 h was sufficient for nearly complete cellulose structural transformation to an accessible amorphous form. The pretreated cellulosic residues were hydrolyzed by a crude enzyme preparation from Penicillium chrysogenum BCC4504 containing cellulase activity combined with Aspergillus flavus BCC7179 preparation containing complementary β-glucosidase activity. Saccharification yields of 84.0% and 70.4% for glucose and xylose, respectively, were obtained after hydrolysis at 45 °C, pH 5 for 72 h, which were slightly higher than those obtained with a commercial enzyme mixture containing Acremonium cellulase and Optimash BG. A high conversion yield of undetoxified pretreated bagasse (5%, w/v) hydrolysate to ethanol was attained by separate hydrolysis and fermentation processes using Pichia stipitis BCC15191, at pH 5.5, 30 °C for 24 h resulting in an ethanol concentration of 8.4 g/l, corresponding to a conversion yield of 0.29 g ethanol/g available fermentable sugars. Comparable ethanol conversion efficiency was obtained by a simultaneous saccharification and fermentation process which led to production of 8.0 g/l ethanol after 72 h fermentation under the same conditions. This study thus demonstrated the potential use of a simple integrated process with minimal environmental impact with the use of promising alternative on-site enzymes and yeast for the production of ethanol from this potent lignocellulosic biomass.     

玉米秸秆发酵生产燃料乙醇的预处理技术研究进展

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。     

乙酸预浸渍用于小麦秸秆蒸汽预处理生产纤维素乙醇

通过改进传统蒸汽爆破预处理方法,利用两步法对小麦秸秆进行预处理.在蒸汽爆破前加入乙酸溶液预浸渍,有效的提高了后续同步糖化发酵的水平.采用乙酸预浸渍气爆预处理后的整个草浆和固形物同步糖化发酵乙醇浓度分别达到25.Sg/L、30.6g/L,分别达到葡萄糖乙醇理论产率的77％、90％;相比传统气爆,草浆和固形物同步糖化发酵乙醇浓度分别仅为17.5g/L、29.2g/L,葡萄糖转化为乙醇仅分别达到理论产率的63％、85％.通过提高固形物浓度到20％,乙酸预浸渍气爆处理后的固形物同步糖化发酵乙醇浓度可达67.3g/L,达到葡萄糖乙醇理论产率的96％.乙酸预浸渍气爆预处理能有效的减少抑制物的生成,提高木质纤维素结构破坏程度以及糖的回收率.     

The effects of genetic and phenotypic production potential on response to recombinant bovine somatotropin.

Evidence was sought for an interaction between both phenotypic and genetic production potential and response of milk production to administration of bST in three trials of 38, 43, and 35 cows. In each trial, bST was administered in doses of 0, 10.3, 20.6, and, in trial 1 only, 41.2 mg/d for 38 wk from wk 4 of lactation. Data were analyzed for each experiment separately and combined across experiments. Analyses included separate regressions for treated and untreated animals for milk production during the production period on pretreatment production and estimated breeding value for milk production. Breeding value was estimated as the sire's estimated transmitting ability plus one-half of the maternal grandsire's estimated transmitting ability. With the exception of regression on estimated breeding value in trial 1 and in combined data, differences between treated and untreated animals in the regression of milk production on pretreatment milk production or on estimates of breeding value were not statistically significant. However, regressions on pretreatment production were substantially lower for treated than for untreated animals in each of the three trials. Regressions on breeding value estimated from sire and maternal grandsire estimated transmitting abilities were substantially, but not significantly, lower for untreated than for treated animals in all three trials. The results suggest that cows with high production potential for nongenetic reasons may show diminished response to bST, whereas cows with genetically high production potential show enhanced response. However, borderline statistical significance argues for considerable further examination before drawing firm conclusions.     

霜桑叶米酒的生产工艺研究

桑叶是食药两用物品,具有较好的保健作用。本文对霜桑叶米酒的生产工艺进行了研究,结果表明,霜桑叶米酒的生产工艺条件为:菌种为马利酵母,霜桑叶预处理方式为热蒸处理3 min,霜桑叶表面积为0.02-0.08 cm2,霜桑叶添加量为0.03 g/g大米,霜桑叶添加时间为落缸时添加。在此条件下制得的霜桑叶米酒多酚含量为0.11 mg/mL,游离氨基酸含量为2.72 mg/mL,DPPH消除率为92.26%,具有较高的营养价值和较好的开发前景,为开发丰富的桑叶资源提供理论依据。     

Effective enzyme saccharification and ethanol production from Japanese cedar using various pretreatment methods

We investigated an effective method for the pretreatment of Japanese cedar for efficient enzymatic saccharification and ethanol production. A 45-atm steam explosion provided a comparatively large amount of glucose and reducing sugars. Addition of polyethylene glycol (PEG) influenced the digestibility of holocellulose in a 35-atm steam-exploded sample. However, we observed a negative effect on enzymatic saccharification when sodium hydroxide was used in the pretreatment. The maximum values of glucose and reducing sugars produced using consecutive pretreatments with a 25-atm steam explosion and an ionic liquid were 408 and 462 mg/(g initial dry sample), respectively. The most positive effects on the enzymatic saccharification kinetics were observed when the above consecutive pretreatment methods were used. However, using the organosolv treatment of wood chips without the steam explosion is a more cost-effective pretreatment method for the enzymatic saccharification of Japanese cedar, and this results in 386 and 426 mg/(g initial dry sample) of glucose and reducing sugars, respectively.