蔗渣纤维在沥青路面的应用

蔗渣纤维沥青路面技术是交通运输部科技示范工程钦北改扩建项目中运用的一项新型农林固废路用技术,其通过机械劈分、物理化学改性、筛分等工序,将产糖尾料甘蔗渣制成路用蔗渣纤维,再以科学的配比和方式掺入沥青混合料中,用于沥青路面铺筑。该技术工程应用表明,蔗渣纤维与传统进口木质素纤维改性沥青混合料性能相当,可显著提升沥青路面抗车辙性能、抗低温开裂性能、水稳定性及疲劳性能等。     

热改性橡胶木防止粉蠹虫害分析

考察热改性橡胶木在海南岛自然环境下遭受粉蠹虫害的程度、热改性前后木材淀粉和游离糖含量变化。结果表明:橡胶木素材未经过传统的硼化物加压浸注防腐处理,1 a后遭受粉蠹虫蛀,185℃/3 h和215℃/3 h热改性的炭化橡胶木在海南自然条件下放置3.5 a,试材未受到粉蠹虫危害。橡胶木素材中淀粉含量为6.69%,蔗糖占索氏抽提成分比例9.96%,经过高温热改性后,其淀粉与蔗糖含量大幅度降低,200℃/3 h淀粉含量降低为1.03%、蔗糖占索氏抽提成份比例降低为0.67%。     

国内大豆胶粘剂的改性研究进展

大豆胶粘剂是一种绿色环保胶粘剂,在人造板领域具有很大的应用潜力.为改善大豆胶黏剂的耐水胶合性能及防腐性能,人们进行了大量的改性研究,其中耐水胶合性能的改性研究较多,包括物理改性、尿素改性、酸碱盐改性、接枝共聚、共混改性、有机试剂改性、晶须、纳米改性等.该文对目前国内有关大豆胶粘剂的改性研究进展进行了综述.     

中国茶树的粉虱新记录——粉背刺粉虱(半翅目:粉虱科)

记述了茶树上一新记录粉虱——粉背刺粉虱Aleurocanthus inceratus Silvestri,该种亚缘区有11对长度一致的刺毛,其中头胸部5对;在背面中区头胸部有刺毛9对;腹部背面中区有14对,纵向分列3排;管状孔近圆形,盖瓣心形,尾沟不明显。统计了茶树上的9种粉虱即山茶褶粉虱Aleurotrachelus camelliae(Kuwana)、杨梅类伯粉虱Parabamisia myricae(Kuwana)、黑刺粉虱Aleurocanthus spiniferus(Quaintance)、番石榴白棒粉虱Aleuroclava psidii Singh、流苏子瘤粉虱Aleuroclava thysanospermi(Takahashi)、归亚瘤棒粉虱Aleuroclava guyavae(Takahashi)、杜鹃穴粉虱Aleurolobus rhododendri Takahashi、柑橘裸粉虱Dialeurodes citri(Ashmead)和粉背刺粉虱Aleurocanthus inceratus Silvestri,根据其伪蛹特征编制了茶树上粉虱分类检索表。     

大豆磷脂改性技术综述

简要介绍大豆磷脂功能特性和大豆磷脂的改性现状,介绍了大豆磷脂酰化、羟基化和氢化等化学改性的原理、工艺和不同改性磷脂产品的制备及应用.通过化学改性改善磷脂的乳化性,提高其亲水性,但化学改性破坏了磷脂的天然结构,所以只有部分化学改性的磷脂产品得到了应用.酶改性具有反应物不需纯化、反应条件温和、速度快、进行完全、副产物少、酶制剂作用部位准确等优点.应用最多的是磷脂酶,包括磷脂酶A1、A2、C、D.磷脂的酶改性中最有意义的酶是磷脂酶A2和磷脂酶D.     

大豆蛋白薄膜改性技术研究进展

大豆蛋白膜因其无污染、可生物降解、来源广泛及透气性低等优点,成为当前的研究重点.但其抗拉强度低、延伸率较差且易导致细菌滋生,致使其应用受到严重影响.因此需要对大豆蛋白薄膜进行改性,以适应不同的用途.本文介绍了用于提高大豆蛋白使用性能的薄膜物理改性、纳米材料改性、化学改性、混合改性、酶法改性等改性方法,总结目前大豆蛋白薄膜的主要应用领域和需要解决的问题,并展望其发展方向.     

茶多酚改性及其抗氧化性能研究进展

利用溶剂法、乳剂法和分子修饰法等技术对茶多酚进行改性,以制备具有较好脂溶性的改性茶多酚一直是国内外研究的热点之一。本文就目前用于茶多酚改性的三种方法及其优缺点,以及改性后的脂溶性茶多酚的抗氧化性能与机理进行了综述和总结,并对茶多酚改性技术发展与脂溶性茶多酚应用前景进行了展望。     

超声波改性大豆蛋白研究进展

大豆蛋白资源丰富,具有良好的营养功能和独特的加工特性,是优质的植物蛋白资源之一。但大豆蛋白天然的功能特性不能够满足实际应用,因此需要对其改性。本文简要介绍了大豆蛋白的组成、功能特性及其改性现状,主要综述了超声波改性对大豆蛋白的溶解性、乳化性、起泡性、凝胶性等功能特性的影响,并简单介绍了大豆蛋白经超声波改性后的应用现状,为深入了解超声波改性大豆蛋白作用机理、拓宽改性大豆蛋白的应用范围提供参考。     

剑麻粉蚧的为害与综合防治技术

针对剑麻粉蚧为害现状,调研、分析了剑麻粉蚧生物学特性与发生传播规律,根据粉蚧虫害及危害程度,提出了剑麻粉蚧的综合防治技术。     

大豆基胶黏剂改性的研究进展

大豆蛋白的凝胶性能够使大豆分离蛋白具有较高的粘度、可塑性和弹性,由大豆分离蛋白形成的胶黏剂不会释放甲醛等有害气体,是高环保型胶黏剂.但是普通大豆胶黏剂耐水性差、胶合强度低,而且耐腐蚀性差、易于生物降解,所以需要进行改性处理以期提高耐水性以及胶合强度.常用改性方法包括:物理改性、化学改性、仿生改性、酶改性等,通过对大豆蛋白改性处理方法的归纳,介绍了大豆胶的最新研究动态,以及国内外大豆胶改性的先进技术,从而总结出适宜的改性方法,为实际的生产与应用提供依据.     

Impact of long-term frozen storage on the dynamics of water and ice in wheat bread

Frozen storage of bread has a substantial impact on the dynamics of water and ice in the crumb and crust. In this study, the impact was characterized using wheat bread stored at −18 °C for a long term of ∼4 months. The frozen bread incurred a considerable loss of the crumb water that migrated out and formed ice crystals on the bread surface. Such a moisture decrease underwent more rapidly for the bread stored without intact crust, suggesting the specific role of crust during frozen storage. Moisture also redistributed significantly within the frozen crumb, resulting in an elevated crumb heterogeneity of freezable water. This redistribution of freezable water was accompanied by a progressive recrystallization of the crumb-borne ice crystals, which were measured to grow into bulk sizes using a modified calorimetric procedure for analyzing the crumb samples at their as-frozen states.     

Mechanical Properties of Bread Crumb Prepared from Flours of Different Dough Strength

Bread quality depends in part on the textural properties of the crumb; softness and strength being two important textural attributes. This study examined differences between instrumentally-measured textural properties of the crumb of bread made from two flours; one possessing extra strong dough mixing characteristics and a second of moderate strength (red spring wheat). Bread crumb specimens, notched and un-notched, were subjected to tensile loading and the crumb's initial (elastic) modulus, stress at failure (crumb strength) and tear resistance were determined. The same mechanical parameters were determined on bread crumb that had been compressed approximately five-fold in order to destroy crumb structure. For un-notched specimens, stiffness and strength were of the order of 11 and 1 kN/m², respectively, whereas after compression they were 230 and 10 kN/m², respectively. For CWRS breadcrumb, toughness increased from 4·1 J/m²to 12·3 J/m²following crumb compression. Bread crumb made from a flour possessing extra strong dough properties was stronger than bread crumb made from a more conventional red spring wheat flour, and there was an indication that extra strong flour bread crumb specimens were stiffer. Compression of the bread crumb lessened the difference between the mechanical properties of the two bread types, particularly for strength and tear resistance. The results indicated that bread crumb structure plays a predominant role in the textural properties of bread crumb.     

The Role of Dextrins in the Stickiness of Bread Crumb made from Pre-Harvest Sprouted Wheat or Flour Containing ExogenousAlpha-Amylase

Dextrins were extracted in water from bread made from pre-harvest sprouted wheat or standard flour supplemented with exogenousalpha-amylases. The dextrins were separated by gel permeation chromatography and the dextrin content (% of crumb weight) determined for different degree of polymerisation (DP) size classes; DP 1–2, DP 3–10, DP 11–50, DP 51–200 and DP >200. There were significant correlations between the dextrin content in each size class and crumb stickiness (r=0·84–0·91, 22 df ). The most significant correlation (r=0·96) was between total dextrin content and crumb stickiness. Addition of dextrins of various DP ranges from various sources to standard flour produced bread with sticky crumb. Again, the degree of stickiness was generally related to the amount of total dextrin in the crumb and not to size distribution of dextrins. In this instance, extensive enzymic hydrolysis of starch was not necessary to produce sticky crumb; the dextrins caused crumb stickiness directly. Addition of dextrins to reconstituted gluten–starch flour produced bread with unexpectedly low dextrin levels and correspondingly low stickiness scores. It is concluded that, to produce sticky crumb, high levels of dextrin of any size are necessary in the crumb; a sticky mass is produced when dextrins dissolve in the excess «free» water that is normally «bound» to starch, gluten and other insoluble components of bread crumb.     

Influence of Starch Granule Size Distribution on Bread Characteristics

The granule size distributions of starches isolated from eight bread wheat flours were determined. Breads were baked from the same flours by varying fermentation time, mixing speed and work input according to a central composite experimental design. Response surface equations were calculated for the bread characteristics loaf volume, weight, form ratio (height/width) and crumb firmness. Multivariate regression (PLS2) was used to relate the starch granule size distribution spectra to the coefficient matrices. The models obtained by PLS2 explained 55% and 48% of the total variance in the response surface coefficients for bread weight, and form ratio respectively, with correlation coefficients 0·74 and 0·69. No models were obtained for crumb firmness and loaf volume. The correlations obtained with the constant terms indicated that high weights and form ratios were promoted by small A-granules (size 12 μm). The effect of starch granule size distribution on the bread characteristics was modified by work input and mixing speed, while fermentation time had no effect.     

Waxy durum acts as a unique form of crumb softener in bread

Flour milled from waxy durum grain was incorporated into bread formulations and its effects on crumb softness and loaf volume compared to those of added fats and emulsifiers. Waxy durum had a small effect on increasing loaf volume, and little of this effect could be explained by dough height or oven spring; effects of most other additives were closely related to dough height or oven spring. For all additives, the relationship between crumb softness and loaf volume fitted a power law relationship. Waxy durum and some of the additives had a greater softening effect than predicted from their effect on volume while others produced a much firmer crumb. With only one exception, when combined with other additives waxy durum reduced compression of the crumb more than predicted on the basis of the effects on loaf volume of the additives alone. In common with some of the added lipids, during compression analysis, crumb prepared with waxy durum flour had similar levels of structural damage as crumb baked from the standard formulation; other lipids and emulsifiers produced more fragile crumb. Waxy durum flour appears to have unique effects on crumb softness.     

天甲橡胶改性陶土与NR的相互作用

用天甲橡胶(MG49)改性陶土。通过IR、SEM及结合胶含t、表观交联密度、界面作用表征值、姗变和力学性能的测定,研究改性陶土与NR的相互作用及改性效果。结果表明:MG49湿法改性陶土提高了混炼胶的结合胶含量,增加了材料的表观交联密度,增强了陶土与NR间界面的作用强度,改善了硫化胶的网络结构,提高了硫化胶的力学性能     

Impact of the baking kinetics on staling rate and mechanical properties of bread crumb and degassed bread crumb

This paper presents a study on the impact of baking conditions on crumb staling. Breads were baked at 220 °C, 200 °C and 180 °C corresponding to 6, 8 and 10 min to rise the temperature to 98 °C in the crumb (heating rates 13, 9.8 and 7.8 °C/min respectively with an initial temperature of 20 °C). A new protocol has been developed, consisting in baking a slab of degassed dough in a miniaturized oven to mimic the baking conditions of conventional bread making. Texture tests were done during staling on degassed crumb and on conventional crumb. Calorimetry tests showed that during storage, amylopectin recrystallisation occurred before crumb stiffening. A first order kinetics model was used to fit the evolution of the crumb texture (Young's modulus) and of the recrystallisation of amylopectin. The results showed that the hardening of the crumb during staling occurred after retrogradation of amylopectin. In addition, the staling rate was faster for faster baking kinetics. A mechanical model showed that the relative Young modulus is proportional to the square of the relative density of the crumb.     

Does crumb morphology affect water migration and crispness retention in crispy breads?

Crispness of bread is rapidly lost because of water migration inside the crumb towards the crust. How crumb properties determine this process independent of crust properties has not been examined before. Therefore, the aim of this study was to analyze and explain the influence of crumb morphology on the overall crispness retention. Crispness retention was determined by analyzing the acoustic emission of breads differing in either crust or crumb morphology. When crumb morphology is coarse with a lower number of large connections between the air cells, the effective diffusion coefficient is reduced. This effective diffusion coefficient of crumb, which equals approximately half the value of air, was estimated using X-ray micro-computer tomography images of crumb pieces. If the crumb has a lower effective diffusion coefficient, bread with similar crust properties has significantly longer crispness retention. Despite this, our data show that variations in properties of crust, which has 30 times higher permeability than crumb, have a larger impact on crispness retention than variations in properties of crumb.     

云南山地胶园橡胶树专用肥肥效研究

在云南山地胶园,对缺氮(镁)型、缺氮钾(镁)型橡胶树开展专用肥施用效果研究。3 a试验结果表明：与常规施肥相比,施用高氮(镁)型、高氮钾(镁)型橡胶树专用肥,单位面积年平均干胶增产率分别为8.63%、9.69%;年平均增产干胶70.37 、96.04 kg/hm2;减少肥料投入891、679元/ hm2,产生经济效益分别为2 298、2 600元/hm2;橡胶树茎围分别增长6.78%、10.79%;橡胶树叶片N、Mg含量增加,K、Ca含量在正常值范围内。对症施用橡胶树专用肥比常规施肥增产效果好、肥料投入少、经济效益高,改善了橡胶树叶片营养状况,促进橡胶树生长。     

胶园间种柱花草的生态适宜性及间作效益评价

在幼、中、成龄胶园中进行了柱花草间种的生态适宜性试验。结果表明,仅幼龄胶园可以间种,间种后土壤肥力略有下降,对胶树生长亦有一定影响,但无显著差异,柱花草产量为全光照的46．5％。中、成龄胶园不宜间种柱花草,原因是：（1）中、成龄胶园内光照太弱,上午10：00平均仅为全光照的13％;（2）中、成龄胶园行间整地后橡胶营养根系生长迅速,密布土壤表层,柱花草无法同其竞争;（3）中、成龄胶园柱花草长势弱,易遭受从橡胶树冠落下的雨滴打击,林地湿度较大,炭疽病十分严重易导致衰败。对Wasana的PER和LER评价公式进行了修正,建立了土壤养分均衡率公式,采用了Wasana的IER经济效益评价公式,对幼龄胶园间作柱花草的效益进行了评价。