浸油用玉米胚挤压膨化预处理技术的试验研究

该文通过4因素5水平二次正交旋转组合试验，研究了用于浸油的玉米胚挤压膨化预处理过程中的挤压系统参数(套筒温度、模孔孔径、物料含水率、螺杆转速)对考察指标(残油率、剪切强度、密度)的影响规律。得到最佳挤压工艺参数：模孔直径9 mm，物料出口温度93℃，喂入物料含水率13.3%，螺杆转速238 r/min，在此条件下得出残油率最优值为0.40%。和传统工艺相比，浸提时间缩短一半，膨化物的密度与轧坯和预轧样相比分别增加29.3%和13.8%。只要参数选择合适，可使原设备的浸出能力提高60%～120%。     

挤压膨化工艺参数对玉米淀粉出酒率的影响

合理的原料预处理工艺可以提高玉米淀粉出酒率,该文用单螺杆挤压膨化机对脱胚玉米进行挤压膨化,以模孔直径、套筒温度、物料含水率、螺杆转速和酵母添加量作为因素,以挤压膨化脱胚玉米淀粉出酒率为考察指标,采用5因素5水平(1/2实施)进行二次正交旋转组合试验设计,探讨了挤压膨化工艺参数和酵母添加量对挤压膨化脱胚玉米淀粉出酒率的影响规律,得到了优化的工艺参数:模孔直径为12mm,套筒温度140℃,物料含水率19%,螺杆转速200r?min-1,在酵母添加量为0.4%时,玉米淀粉出酒率可以达到55.81%。     

双螺杆二次挤压法制备方便米饭的工艺研究

该文采用可旋转中心组合设计,综合考查机筒温度、物料湿度和螺杆转速三个变量对挤压方便米饭复水率的影响,推导出描述复水率的二次回归模型,并对变量进行响应面分析,得出最佳工艺条件为:机筒温度为120℃、物料湿度为33%,螺杆转速为200 r/min.在该条件下制得的方便米饭复水3 min后,复水率达285%,硬度和弹性值都达到原料籼米米饭的水平.     

菜籽挤压膨化系统参数对出油率影响的试验研究

该文研究了用于浸油的一种菜籽挤压膨化预处理工艺(油菜籽清理—带壳粉碎—膨化—浸油)的可行性，油菜籽挤压膨化系统参数(模孔孔径、套筒温度、物料含水率、螺杆转速)对各考察指标(粕的残油率、膨化物含油率及榨笼出油率)的影响规律，挤压膨化系统优化参数的范围为模孔孔径8～12 mm、套筒温度105～125℃、物料含水率6.6%、螺杆转速35～55 r/min。研究表明：只要参数选择合适，带壳油菜籽清理、粉碎、挤压膨化、浸出的菜籽浸油预处理工艺是可行的，且残油率较低。该菜籽挤压膨化浸油预处理工艺可供生产参考。     

鸡肉-大米膨化食品双螺杆挤压工艺参数的优化研究

以鲜鸡肉和大米为原料，对双螺杆挤压工艺条件进行研究，以期开发出新型鸡肉挤压膨化休闲食品，提高鸡肉的附加值。试验采用可旋转中心组合设计，综合考查物料湿度(X₁)、机筒温度(X₂)和螺杆转速(X₃)三个变量对糊化率(Y)的影响。在此基础上由试验数据推导出描述糊化率的二次回归模型，并对变量进行响应面分析，得出最佳挤压工艺条件为：物料湿度35％、机筒温度123℃、螺杆转速220 r/min。     

挤压加工参数变量对重组米生产过程中系统参数与产品膨胀度的影响

试验以杂交籼米为原料,利用响应面模型,研究双螺杆挤压生产重组米过程中螺杆转速(60-180rpm)、进料速度(20-60g/min)、物料水分含量(22-42%)以及末端机筒温度(80-100℃)对挤压系统参数和重组米膨胀度的影响。结果表明,压强、比机械能和产品膨胀度都受到四个挤压变量的显著影响,但是物料温度受进料速度影响不显著,马达扭矩受末端机筒温度影响不显著,产品水分含量仅受进料水分含量的显著影响。比机械能与螺杆转速正相关,与进料速度、物料水分含量和末端机筒温度负相关。所得二次回归模型均拟合情况良好,,达到设计要求。可以认为本文建立的挤压数学模型可以应用于重组米生产领域,为重组米工业化生产的过程预测和产品性质预测提供一定帮助参考。     

挤压膨化预处理工艺优化提高大豆蛋白粉品质

该文对大豆挤压膨化预处理工艺进行研究,制得优质膨化大豆蛋白粉。以大豆为原料,研究利用挤压膨化机对经破碎及调质的大豆进行处理,替代部分预处理工序,再经榨油机榨出部分油脂制得膨化大豆蛋白粉的方法。试验通过单因素和响应面优化试验研究挤压膨化大豆含水率、膨化温度、螺杆转速和模孔孔径对大豆脲酶活性的影响,结果表明:当调质含水率为9.0%、膨化温度160℃、螺杆转速270 r/min及模孔孔径18 mm时膨化后大豆脲酶活性为0.021 U/g,同时经透射电镜显示膨化后大豆中的脂肪外露明显,经榨油机压榨再经粉碎制得膨化大豆蛋白粉,豆粉中脂肪质量分数7.1%,氮溶解指数(nitrogen solubility index,NSI)80.5%,实现了通过挤压膨化替代软化、轧坯、蒸炒工艺,简化了生产工序。     

挤压加工参数对重组米生产过程及产品膨胀度的影响

为了考察重组米生产过程中挤压加工变量对几种系统参数与产品膨胀度的影响,试验以杂交籼米（9?718品种）为原料,利用响应面模型,以螺杆转速、进料速度、进料含水率以及末端机筒温度为输入变量,以挤压系统参数（物料温度、模头压强、扭矩、比机械能和产品含水率）和重组米膨胀度为响应变量,探索在重组米生产过程中加工变量与系统参数及产品膨胀度的关系。结果表明,压强、比机械能和产品膨胀度都受到4个挤压变量的显著影响,但是物料温度受进料速度影响不显著,马达扭矩受末端机筒温度影响不显著,产品含水率仅受进料含水率的显著影响。比机械能与螺杆转速正相关,与进料速度、进料含水率和末端机筒温度负相关。所得二次回归模型均拟合良好,建立的挤压数学模型可应用于重组米生产,为重组米工业化生产的过程预测和产品性质预测提供参考。     

不同挤压参数对大豆粕蛋白质结构的影响

该文系统研究了油脂提取前挤压膨化预处理工艺对大豆粕蛋白质表面疏水性、游离巯基含量的影响，分析了物料水分、膨化温度、δ段长度、模孔长度、螺杆转速等不同挤压参数与蛋白质结构变化的关系，建立了挤压参数与粕蛋白质游离巯基含量关系的量化模型。结果表明：低物料水分、低膨化温度、短模孔可以减少挤压膨化预处理工艺过程中蛋白质结构的破坏程度。相反，高物料水分、高温挤压膨化时，会加剧蛋白质分子内部疏水基的暴露和蛋白质的交联。在此基础上改进的挤压膨化预处理工艺更有利于蛋白质结构的改善。     

水产沉性颗粒饲料挤压蒸煮工艺对其理化特性的影响

为了规模化生产出低污染、高转化率的环保型水产沉性颗粒饲料,选用双螺杆挤压机对水产全价配合原料进行挤压熟化研究。以沉性水产硬颗粒饲料理化特性(膨化度、近似密度、糊化度、耐久性和水中稳定性)为重要指标,采用表面响应分析法研究了物料含水率（22%～38%）、套筒温度（70～170℃）和螺杆转速（73～107?r/min）对其挤压工艺和饲料理化特性的影响规律,SEM分析其微观结构。结果表明：物料含水率、套筒温度和螺杆转速均显著影响饲料的理化特性。中高物料含水率和套筒温度及低螺杆转速时,才能获得理想的沉性高熟化水产颗粒饲料,其理化特性具有低膨化度（1.14）,高近似密度（757.6?g/L）、糊化度（879.5?g/kg）、耐久性（96.6%）和水中稳定性（88.7%）。SEM分析显示优化条件（物料含水率31%,套筒温度126℃,螺杆转速78?r/min）下生产的颗粒饲料结构光滑质密。该研究可为发展高效、低耗、低碳高品质沉性水产饲料研究和生产提供参考。     

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。     

挤压法生产淀粉糖浆副产物酶解条件

为实现低值蛋白质资源玉米渣的高质化利用,采用2709碱性蛋白酶,水解挤压法生产淀粉糖浆的副产物玉米渣,确定水解工艺条件.并对水解液中的肽分子质量分布状况及氨基酸组成进行了分析.结果表明,按照本研究工艺路线,采用2709碱性蛋白酶能够较为彻底地水解目标副产物中的蛋白质,水解液中分子质量小于10000 u的水解物大于总量的94.8%,并且绝大部分水解物在二肽、三肽分子质量范围内分布,水解液中含有能够满足人体生理机能需要的多种氨基酸.     

Leaf mineral element concentrations and growth of sweet sorghum subjected to acid soil stress

Abstract

The nutritional profile of sweet sorghum [Sorghum bicolor (L.) Moench] cultivars grown under acid soil field stress conditions is a critical consideration when developing plants which are adapted to these infertile soils. Uptake and accumulation of macro‐ and micronutrients vary among genotypes and ultimately Influence plant growth and development. This study compared fourteen sweet sorghum germplasm lines and varieties for their Individual patterns of leaf nutrient concentrations and productivity when grown under acid soil field conditions (pH 4.45 to pH 4.85) at three locations over a two‐year period. Significant year x location interactions were found for Fe, K, and Ca concentrations at both Blairsville and Calhoun and for Mn and P levels at Blairsville and Calhoun, respectively. Data from Calhoun on plant height, dry weight, visual stress ratings, and rainfall indicate a possible association between drought tolerance and acid soil tolerance in sorghum. No significant differences in A1 concentrations were found among these sweet sorghum lines and varieties, which indicate that their acid soil tolerance mechanisms are probably not related to A1. MN 1054 accumulated the highest levels of Mn in the three acid soils. The highest concentrations of Mg and P were found in Brandes. MN 960 had the highest visual stress ratings (highest susceptibility) while Brandes, Ramada, Roma, and Wray were the most tolerant. All fourteen cultivars apparently have some tolerance to acid soil stress conditions.     

适宜干燥方法提高干制枸杞品质

为缩短鲜枸杞的干制时间,获得高品质的干制枸杞,该文通过比较自然晾晒、燃煤烘干房以及太阳能干燥设备对枸杞的干燥效率的差异以及测定并分析3种干燥方式获得干果的主要功能性成分（总糖、总黄酮、多糖、甜菜碱,类胡萝卜素）含量及外观品质和出糖率的差异。试验结果表明,采用太阳能干燥设备干燥枸杞的时间最少约为26 h,功能性成分总质量分数约71.71 g/(100 g),与其他2种干燥方式相比功能性成分损失降低,干枸杞色泽更接近鲜枸杞的色泽,出糖率约为1.53%,低于其他2种干燥方式。太阳能干燥设备对于枸杞干燥具有显著的优势,应用前景广阔。     

塔里木河中下游河道整治方法之探讨

如何利用现有的常规方法在粉细沙河床上修建永久防洪护堤工程,因其工程造价过高致使社会难以承担;为此,提出采用斜向灌浆护坡新技术修建永久性防洪护堤。由于灌浆护坡具有抗冲强度中等、抗冲耐久性较好、施工快捷方便、造价低廉等优点,在粉细沙河床的河道治理工程中将具有广阔的应用前景。     

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,     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.