挤压蒸煮大米啤酒辅料的糖化过程分析

为了合理地确定挤压蒸煮大米啤酒辅料的糖化工艺参数,通过挤压蒸煮大米不同糖化工艺的效果及传统蒸煮大米啤酒辅料糖化工艺的比较,分析了糖化过程。研究表明,两种大米啤酒辅料的糊化本质是相同的。不同的是,传统蒸煮大米啤酒辅料的双醪糖化工艺中的大米糊化过程中,包括了大米淀粉的糊化和液化过程;挤压蒸煮大米啤酒辅料仅完成了大米的糊化过程,其液化过程是在单醪糖化过程中完成。为此应调整挤压蒸煮大米的糖化工艺,充分发挥麦芽中的β-淀粉酶、α-淀粉酶及添加的耐高温α-淀粉酶的作用,使挤压蒸煮大米啤酒辅料的单醪糖化过程顺利进行,解决其糖化、过滤困难问题。     

两种淀粉酶的酶学性质及应用研究

研究了两种耐高温α-淀粉酶和两种真菌α-淀粉酶的酶学性质，确定了最佳酶反应条件。将其应用于淀粉糖生产中，以30%的玉米淀粉为原料，用进口耐高温α-淀粉酶水解至还原糖含量为16.5%，再用日本真菌α-淀粉酶在最佳条件下反应21 h，可得到含纯麦芽糖31.1%、葡萄糖1.7%、糊精2.7%的高麦芽糖浆。     

两种淀粉酶的酶学性质及应用研究

研究了两种耐高温α-淀粉酶和两种真菌α-淀粉酶的酶学性质,确定了最佳酶反应条件.将其应用于淀粉糖生产中,以30%的玉米淀粉为原料,用进口耐高温α-淀粉酶水解至还原糖含量为16.5%,再用日本真菌α-淀粉酶在最佳条件下反应21 h,可得到含纯麦芽糖31.1%、葡萄糖1.7%、糊精2.7%的高麦芽糖浆.     

低温挤出-多酶协同降解脱胚玉米中淀粉的机理

为了改变目前挤出酶解谷物淀粉仅添加一种酶制剂(α-淀粉酶),只能降解淀粉的α-1,4糖苷键,不能降解支链淀粉的α-1,6糖苷键,限制淀粉转化成葡萄糖的收率进一步提高的现状,该文应用低温(≤80℃)挤出-多酶(α-淀粉酶、糖化酶、普鲁兰酶)协同降解技术,制备挤出过程中物料的石蜡显微制片,观察脱胚玉米经低温挤出-多酶协同降解处理后,细胞壁、细胞中的淀粉颗粒和蛋白质颗粒的分布状况以及淀粉含量、糊化度、可溶性糖含量的变化。结果表明:在挤出过程中,淀粉发生糊化和降解,表观淀粉质量分数减少,从81.50%减少到74.40%,可溶性糖质量分数增加,从1.07%增加到2.26%,挤出过程中加入酶制剂后这种变化更加明显。添加单一α-淀粉酶表观淀粉质量分数从79.72%减少到69.16%,可溶性糖质量分数从6.54%增加到7.90%。添加α-淀粉酶和糖化酶表观淀粉质量分数从81.42%减少到72.45%,可溶性糖质量分数从11.65%增加到14.71%。添加α-淀粉酶和普鲁兰酶表观淀粉质量分数从81.31%减少到70.31%,可溶性糖质量分数从6.74%增加到8.29%。添加α-淀粉酶、糖化酶、普鲁兰酶3种酶时淀粉质量分数从81.06%减少到69.05%,可溶性糖质量分数从11.25%增加到16.35%。因此,3种酶(α-淀粉酶、糖化酶、普鲁兰酶)协同作用对淀粉降解以及可溶性糖含量的增加作用效果最好。显微切片的分析结果表明:添加3种酶制剂(α-淀粉酶+糖化酶+普鲁兰酶)的切片,细胞结构中淀粉颗粒被降解破坏的程度大于添加1种(耐高温α-淀粉酶)、2种(α-淀粉酶+糖化酶,或者α-淀粉酶+普鲁兰酶)酶制剂的细胞结构中淀粉颗粒被降解破坏的程度。低温挤出-多酶协同降解后,脱胚玉米挤出物的总淀粉含量降低、可溶性糖含量增加,糊化度增加。试验表明:添加3种酶制剂协同降解脱胚玉米中淀粉的作用效果优于添加1种酶制剂或2种酶制剂的淀粉降解效果,为进一步提高淀粉转化成葡萄糖的收率提供科学依据。     

基于量纲分析的函数理论建立挤压脱胚玉米生产淀粉糖浆的糖化液过滤问题的经验公式

该文应用基于量纲分析的函数理论和蒋亦元修正的G.Murphy定理,扩大试验范围,减少试验次数,研究脱胚玉米挤压系统参数,对挤压脱胚玉米生产淀粉糖浆的糖化液滤速、DE值的影响规律。解决用脱胚玉米挤压膨化物生产淀粉糖浆难于糖化过滤的问题,为在实际生产中使用挤压膨化脱胚玉米生产淀粉糖浆提供参考。     

以黄姜为原料发酵酒精的液化糖化条件的初步研究

利用黄姜根茎富含淀粉的特点,在温和的条件下研究其液化糖化性能,用来发酵酒精。黄姜粉加水调浆后,升至一定温度,加入适量α-淀粉酶进行液化处理,保温一段时间,然后降温至60℃,调pH值,加糖化酶糖化,保温处理使其中的淀粉转化完全。单因素试验结果表明：60目以上黄姜粉,料水质量比1∶5,α-淀粉酶10 U/g,在90℃时,30 min即可达到很好的液化;然后降温到60℃,调pH值4.0～4.5,加糖化酶60 U/g,90 min内基本完全糖化。利用酶解的方法转化黄姜中的淀粉是可行的,并且效果显著。     

脱胚玉米啤酒辅料的挤压蒸煮系统参数对其糖化过程的影响

该文通过实验室试验,研究了作啤酒辅料的脱胚玉米挤压蒸煮系统诸参数(模孔孔径、套筒温度、物料含水率、螺杆转速和模板内表面至螺杆末端端面的距离),对醪液的主要考察指标（麦汁的过滤速度、碘值、浸出物收得率）的影响规律. 研究表明,挤压蒸煮脱胚玉米可以作啤酒辅料,其醪液的淀粉在糖化过程中被降解得彻底,淀粉的利用率较高。     

减少玉米粗淀粉挤出物中抗性淀粉的工艺参数优化

为减少玉米粗淀粉经过挤压蒸煮后,在室温下冷却而产生的抗性淀粉Ⅲ,以降低其对挤出物制备糖化液葡萄糖当量值的影响,需要对挤压参数进行优化选择。该文以玉米粗淀粉为原料,采用五因素五水平二次正交旋转组合试验设计,研究挤压参数对挤出物中抗性淀粉Ⅲ质量分数的影响,得出产生抗性淀粉Ⅲ质量分数最小的挤压条件为：套筒温度60.0℃,原料含水率27.0%,模孔直径11.0 mm,螺杆转速200.0 r/min,轴头间隙10.0 mm,抗性淀粉Ⅲ质量分数可降低到1.48%。     

玉米挤压淀粉酶法改性制膜的工艺优化

为了提高可降解性玉米淀粉膜的力学性能,并获得玉米挤压淀粉酶法改性制膜的最适工艺参数,该研究以普鲁兰酶为酶制剂来改善玉米挤压淀粉膜,以酶作用温度、pH值、酶添加量、酶解时间及玉米挤压淀粉浓度为试验因子,膜的抗拉强度为响应值,采用中心旋转组合试验设计进行试验。结果表明：5个因素对酶改性挤压淀粉膜抗拉强度的影响大小依次为玉米挤压淀粉浓度＞酶添加量＞酶解时间＞pH值＞酶作用温度;最佳酶解制膜工艺条件为：酶作用温度46.57℃,pH值4.44,酶添加量6.63 u/g,酶解时间9.31 h,玉米挤压淀粉浓度7.00%,在此条件下,膜抗拉强度的预测值为24.3654 MPa,验证试验所得膜抗拉强度为24.2539 MPa,比未改性膜的抗拉强度提高了338.01%。回归方程的预测值和试验值差异不显著,所得回归模型拟合情况良好,达到设计要求。膜的抗拉强度与酶解挤压淀粉中直链淀粉含量之间存在极显著正相关关系,相关系数为0.863。     

青稞慢消化淀粉酶法制备技术研究

为了探索酶解处理对青稞慢消化淀粉含量的影响,以青稞淀粉为原料,分别以α-淀粉酶法,β-淀粉酶法,转葡糖苷酶协同α-淀粉酶处理法,转葡糖苷酶协同β-淀粉酶处理法等4种方法制备慢消化淀粉(SDS),通过单因素试验和正交试验确定最佳制备方案。结果表明,制备SDS的最佳方法为转葡糖苷酶协同β-淀粉酶处理法,具体处理条件为:β-淀粉酶的添加量0.032%,转葡糖苷酶的添加量0.192%,酶解时间8h,冷藏回生时间5d,淀粉乳浓度15%。此条件下制备的SDS含量为32.53%。本研究结果为青稞慢性消化淀粉产品的开发利用提供了科学依据和技术参考。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.