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针对流域生态安全研究的复杂性和重要性,选取吉林省辽河重污染支流——招苏台河流域作为研究区,应用突变理论中的突变基数法,结合压力—状态—响应框架结构建立了招苏台河流域生态安全突变模型。研究了2004年、2008年、2010年流域内8个乡镇的生态安全状况。研究区2010年生态安全状况总体较2008年呈下降趋势,3个乡镇生态安全处于较好等级,3个乡镇处于预警等级,2个乡镇已降至中警等级。流域生态安全下降的情况应引起足够重视,在采取增加环境保护资金投入和乡镇污水处理厂建设等有效措施,提高生态安全等级的前提下,才能实现流域社会、经济、环境的可持续发展。 相似文献
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GIS支持下乡镇域土壤肥力评价与分析 总被引：22，自引：2，他引：20
在地理信息系统支持下,以鄂南典型红壤丘陵区为例,研究了乡镇域土壤肥力评价的方法和过程,分析了土壤肥力变化原因。结果表明,应用ＧＩＳ对乡镇域土壤肥力进行评价能克服速率慢、数据更新不方便的缺点,避免乡镇决策者主观判断土壤肥力等级的弊病,为生产和局和用地决策提供准确的科学依据。试区土壤肥务与土壤养分、土地利用和区域经济有关,肥力等级有向中等级变化的趋势。 相似文献
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以小麦粉为对照，对荞麦全粉、荞麦心粉、荞麦麸粉的理化特性进行了分析，参照国际标准分析方法，系统分析了荞麦粉-小麦粉混粉的粉质特性、拉伸特性以及糊化粘度特性等流变学特性。试验结果表明，与小麦粉相比，荞麦粉的粘度很高，β-淀粉酶活性很低，降落值大于1000 s。荞麦籽粒中各营养成分分布不平衡，荞麦麸粉的营养价值高。小麦粉中加入荞麦粉，当荞麦粉比例不超过30%时，混粉尚有较好的加工特性。与荞麦全粉相比，荞麦心粉具有较好的加工性能。 相似文献
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机械超微粉碎与不同粒度常规粉碎对红茶理化特性的影响 总被引：5，自引：3，他引：2
为探究机械超微粉碎对茶叶物性及功能成分浸出特性的影响,该文通过超微粉碎和常规粉碎2种方法制备超微红茶粉和4种粒度的粗粉红茶粉,研究了5种茶粉的粒度分布、微观形貌、比表面积、结晶度、表面氧碳元素比、中红外图谱和功能成分的浸出特性。结果表明:常规粉碎不同粒度茶粉间差异较小,而超微粉碎较大程度地改变了茶叶的物料性质。超微粉碎后,茶粉粒度减小至微米级,比表面积增大,茶粉的结晶度降低,表面暴露的纤维素和半纤维素相对含量增多,而中红外谱图显示超微粉碎茶粉的官能团结构并没有改变。沸水浸提过程中茶多酚、咖啡因、可溶性糖和水浸出物的溶出结果表明:5种茶粉功能成分的浸出量都随时间的增加而增加,经过一段时间后达到平衡。在达到浸出平衡时,不同粒度茶粉的茶多酚和咖啡因含量差异不显著,超微茶粉的可溶性糖含量为4种粗粉的2倍左右,水浸出物比粗粉茶粉提高10%以上。上述研究结果表明:超微粉碎能够有效减小茶粉的粒度,破坏植物的细胞壁结构,使内部成分暴露于表面,此外,组织结构和细胞壁的破坏使不溶的纤维成分转化成可溶性成分,可溶性糖和水浸出物显著增多,超微粉碎能够在一定程度上提高茶粉的有效利用率。 相似文献
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沙蒿籽粉和谷朊粉对燕麦全粉食品加工品质的影响 总被引：2，自引：0，他引：2
为了探讨全燕麦粉面包、馒头加工品质及燕麦粉冷冻面团品质特性，以燕麦全粉为原料，研究了添加沙蒿籽和谷朊粉对燕麦全粉食品(含冷冻面团食品)加工品质改良效果。试验结果表明，谷朊粉对面包制作影响较大；沙蒿籽粉对馒头制作影响较大；沙蒿籽粉和谷朊粉共同使用的效果优于两者单独使用；加入2.5%沙蒿籽粉和8%谷朊粉对燕麦全粉面包和馒头品质改善效果最好。对冷冻面团加工而言，随着冷冻时间的延长面团品质不断下降，冻藏4 d后燕麦全粉冷冻面团面包、馒头品质显著降低。 相似文献
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为了研究加工方式对甜茶速溶粉稳定同位素指纹的影响,进而验证δ13 C、δ15 N用于甜茶及其速溶粉产地溯源的可行性,本试验分别以烘箱烘干和微波杀青2种烘干方式制备甜茶老叶和嫩叶4种原料,采用热水浸提、离心并干燥(喷雾干燥和冷冻干燥)的方法制备甜茶速溶粉,得到喷雾干燥速溶粉(ITSD)、冷冻干燥速溶粉(ITFD)和速溶粉副产物(ITBP)三类加工样品,并采用元素分析-同位素比率质谱仪(EA-IRMS)测定样品中的δ13C、δ15N值。结果表明,不同产地(湖南、四川、江西)甜茶杀青嫩叶δ13C、δ15N值存在显著差异(P<0.05),烘箱烘干法与微波杀青法制得的原料茶δ15N值存在差异,且 δ13C、 δ15N值在速溶粉加工产品(原料、速溶粉及副产物)间存在显著差异(P<0.05),但不同烘干原料制备的所有样品δ13 C、δ15N值之间存在极显著相关(P<0.01)。本研究结果为基于δ13C、δ15N溯源指纹进行甜茶原料或速溶茶粉的产地溯源提供了理论依据。 相似文献
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[目的]评价河南省淅川县是丹江口水库核心水源区生态安全状况,旨在为保障南水北调中线工程功效长久发挥提出相应的调控措施。[方法]以淅川县各乡镇为评价单元,利用改进"PSR"模型、层次分析法和GIS技术,进行淅川县生态安全时空演变规律研究,并运用主成分分析法研究了淅川县生态安全主要驱动因子。[结果](1)淅川县生态安全状况虽有波动但整体好转。与2000年相比,2015年中警和预警状态的乡镇各减少了3个,而较安全状态的乡镇增加为6个。(2)淅川县生态安全空间格局呈东北、西南等级较高,西北、东南等级较低的态势。(3)通过驱动力分析发现淅川县生态安全等级提升的主要原因为积极的环境治理响应。[结论]生态安全的良性转变需通过积极引导人类活动,多筹举措共同作用促进区域生态安全和社会经济的可持续发展。 相似文献
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This study focused on the performance of two hulless barley cultivars (Doyce and Merlin) and one commercial husked (hulled) sample using experimental milling. The purpose was to use experimental milling as a preliminary indicator of the milled streams with potential use for fuel ethanol production and fractions that could be used in food products. Experimental mills designed for flour production evaluation from wheat were Chopin CD1 Auto, Quadrumat Sr, Buhler, and an experimental Ross roller mill walking flow. Results indicate that the shorts had the highest levels of β‐glucan from all the mills. However, the β‐glucan content in the break flours was highest with the roller mill walking flow and the Chopin CD1 for the hulless cultivars. The lowest β‐glucan content in the break flour was found with the Buhler for Doyce. Break flour and, to a slightly lesser extent, reduction flour from all cultivars tested on all mills contained the highest starch content (up to 83%) and are therefore most appropriate for use as feedstock for fuel ethanol production. Conversely, bran and shorts from all cultivars and mills were lowest in starch (as low as 25%), making them ideal as low‐starch food ingredients. 相似文献
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Optimization of flour yield and quality is important in the milling industry. The objective of this study was to determine the effect of kernel size and mill type on flour yield and end‐use quality. A hard red spring wheat composite sample was segregated, based on kernel size, into large, medium, and small kernels, as well as unsorted kernels. The four fractions were milled in three roller mills: Brabender Quadrumat Jr., Quadrumat Sr., and Bühler MLU‐202 laboratory mills. Large kernels had consistently higher flour yield than small kernels across mills, with the Quadrumat Jr. mill showing the lowest flour yield. Mill type and kernel size significantly affected variation in flour protein molecular weight distribution. When compared with larger kernels, flour milled from the small‐kernel fraction contained a higher gliadin fraction and SDS‐unextractable high‐molecular‐weight polymeric proteins, which had positive correlations with bread loaf volume (r = 0.61, P < 0.05) and mixograph peak time (r = 0.84, P < 0.001). Overall, small kernels could contribute to enhancing flour breadmaking quality while having a detrimental effect on milling yield. 相似文献
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R. A. Graybosch C. J. Peterson G. A. Hareland D. R. Shelton M. C. Olewnik H. He M. M. Stearns 《Cereal Chemistry》1999,76(3):428-433
Typical commercial bakeries in the United States are highly mechanized, mass-production facilities. U.S. hard wheat breeding programs use small-scale physical dough testing and pup loaf bake procedures to identify and select improved quality genotypes. The accuracy of such approaches in the prediction of commercial-scale quality performance is poorly understood. Samples from six hard red winter wheat cultivars grown in 11 locations over three harvest years were used to correlate grain hardness, small-scale test bakes, mixograph variables, and various measures of flour protein composition with quality assessments from commercial test laboratories. Samples were milled on both pilot- and small-scale mills. Protein content and 100-g pup loaf volume were more often significantly correlated with commercial test bake variables than all other small-scale variables. Stepwise multiple regression models explained, on average, ≈40% of the variation in commercial test bake procedures. Mixograph properties, pup loaf volumes and absorption, and flour protein content were the most frequent variables identified in model development. Pup loaf bake results on pilot- and small-scale milled flours were highly correlated. Differences in milling technology do not appear to be a significant source of error in relating small-scale test bakes to commercial quality. 相似文献
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The aim of this study was to analyze sulfur content, protein size distribution, and free amino acids in flour mill streams (FMS) and their associations to dough rheology and breadmaking traits. Break FMS had higher nitrogen and sulfur quantities than reduction FMS. The third break FMS had the highest nitrogen and sulfur contents among FMS but low bread loaf volume partly due to high ash content. Sulfur quantity had greater or equivalent correlations with dough rheology and breadmaking properties compared with nitrogen quantity when the effect of percent ash content was removed statistically. FMS also showed significant quantitative variation in HMW polymeric proteins of the SDS‐unextractable fraction that had greater association with sulfur content and dough rheology and breadmaking traits than other protein fractions. Asparagine, which is a major amino acid in flour, was found at higher levels in the third break and third reduction FMS. Ratio of nitrogen to sulfur was significantly correlated with asparagine concentration (r = 0.73, α = 0.01). This study indicates that information on sulfur, protein size distribution, and free amino acid is potentially useful in research for more precise blending of FMS in commercial flour mills to meet customer specifications for high quality flour. 相似文献
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Elieser S. Posner Ana A. Chew‐Guevara Marcelo Mitre‐Dieste Esther Perez‐Carrillo Erick Heredia‐Olea Jeff D. Wilson Sergio O. Serna‐Saldivar 《Cereal Chemistry》2014,91(2):139-145
Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas. 相似文献
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Md. Sharif Hossen Itaru Sotome Makiko Takenaka Seiichiro Isobe Mitsutoshi Nakajima Hiroshi Okadome 《Cereal Chemistry》2011,88(1):6-11
Milling method and particle size affect some properties of rice flour. To prepare ultra‐fine rice flour of <30 μm, hammer and dry jet grinding methods were examined and the effect of particle size on starch damage and pasting properties of the flour were elucidated. A jet mill could make finer flour (<10 μm mean size) with a narrower particle size distribution than a hammer mill could. Starch damage increased dramatically at a mean size of <10 μm. Particles of a similar size (<60 μm) had different levels of starch damage between mills. Not only the particle size, but also the milling method affected the level of damaged starch. Flour samples of ≥45 μm mean size had similar viscosity curves, but samples of <20 μm had different curves. Peak viscosity and final viscosity decreased sharply at <10 μm. Setback viscosity for particles of 3 μm from both brown rice and white rice were higher than the peak viscosity. Stability to heat and shearing stress were decreased for <20 μm flours as the breakdown viscosities decreased. Starch damage and pasting properties of flour ground from the nonwaxy japonica cultivar Koshihikari changed dramatically at a mean size of <10 μm. 相似文献
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C. S. Gaines 《Cereal Chemistry》2004,81(4):549-552
During testing of wheats at the early generation developmental stage, often there is not enough seed to mill for bake testing products such as sugar‐snap cookie diameter. This study reports a prediction equation for sugar‐snap cookie diameter that uses sucrose solvent retention capacity (SRC), wheat milling softness, and flour protein content. A total of 507 wheats were milled using three laboratory milling systems (short, medium, and long mill flow). Prediction equations were similar for all three mills. Standard errors of prediction were <2% of the mean estimate of cookie diameter. Additional observations eliminated lactic acid SRC (an indication of glutenin strength), alkaline water retention capacity (a traditional predictor of pastry quality), and flour yield (the main milling quality characteristic) from the prediction model. 相似文献
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Three types of mills and six milling methods were employed to mill two waxy rice varieties (TCSW1, long grain; TCW70, short grain), and the physicochemical and functional properties of rice flour were examined. The results showed that dry-milling maintained a higher level of the chemical components than other milling methods. Wet-milling slightly increased solubility as test temperatures increased, and significantly increased swelling power at 75 and 85°C for TCSW1 and TCW70, respectively. Hammer and semi-dry hammer milling gave higher percentages of coarse particles (100–300 μm); cyclone and turbo milling led to a more even particle-size distribution, and the wet-milling gave the finest particles (10–30 μm). Dry hammer-milled rice had higher gelatinization and pasting temperatures, and semi-dry grinding milling resulted in the lowest pasting temperature, setback viscosity, and enthalpy value among the mills. The final quality of the two waxy rice varieties was profoundly affected by the mill type and milling method. 相似文献
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为解决小麦粉加工过程追溯质量安全信息交叉、单位个体追溯困难等问题,该研究在分析小麦粉加工流程和追溯关键信息的基础上,研究基于批次清单的信息追溯方法,以加工时间为依据结合高津托图(Gozintograph)数据结构构建批次清单(bill of lots,BOL),实现小麦粉产品信息和关键节点活动信息的精确追溯;在BOL的基础上,利用鱼骨图和Petri网分别描述小麦粉质量追溯点的位置和危害指标;结合山东某面粉厂实际生产参数对追溯模型进行验证,实现小麦粉产品与原料的批次关联和其质量危害传播路径的预测。分析结果表明,通过使用BOL和Petri网追溯模型与传统方法相比实现召回批次数量由7个减少到4个、危害因素查找数量由6个减少到5个。该研究提高了小麦粉追溯精度和缺陷召回效率,为粮食等小颗粒产品加工过程的追溯提供了理论支持。 相似文献
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Michael L. Dunn Sergio O. Serna‐Saldivar Diana Sanchez‐Hernandez Robert W. Griffin 《Cereal Chemistry》2008,85(6):746-752
The corn tortilla plays an integral role in the Mexican diet and is an ideal vehicle for micronutrient fortification. Approximately 60% of corn tortillas in Mexico are produced from nixtamal, with the remainder prepared from masa flour. A process for continuous fortification of nixtamal tortillas was evaluated in two commercial mills in Mexico. A commercial powder dosifier was used to add micronutrient premix containing iron, zinc, folic acid, niacin, riboflavin, and thiamin to nixtamal (1 g/kg) as it was milled. After training and preliminary sampling, mills produced fortified tortillas unassisted for four weeks. Masa flow rates over a four‐day period were 10–12 kg/min in both plants. Premix flow from the dosifier showed good stability, with an average coefficient of variation of 1.6%. Initial results indicated consistency in the fortification process, with significantly increased variation during the four‐week production period. Fortified tortillas had significantly higher levels of all nutrients tested. Micronutrient losses were <11% in all cases except folic acid, which showed an 80% loss. Despite processing losses, fortification resulted in a nearly fivefold increase in folic acid compared with control tortillas. The new fortification process is technically viable and was well received by millers. 相似文献