小麦细胞壁结构对水分迁移的调控作用

为探明小麦糊粉层细胞壁这种由阿拉伯木聚糖和β-(1-3)(1-4)葡聚糖组成的复合多层结构对水分的调控作用,研究了小麦糊粉层细胞壁结构对水分吸收速率、干燥速率和水分子移动性的调控作用。结果表明:通过环境扫描电镜(SEM)筛选出糊粉层最厚的周麦22和糊粉层最薄的中麦895,大麦和青稞作为对比,其中大麦细胞壁厚度是中麦细胞壁厚度的1. 49倍。通过比较周麦22、中麦895、大麦和青稞的糊粉层厚度与水分吸收速率、干燥速率的关系,说明了糊粉层细胞壁与吸水、干燥速率呈负相关。通过低场核磁共振检测发现:相同吸水条件下,糊粉层细胞壁越厚的样品其体内含水量越低但体内水分子的移动性越好;在干燥条件下,糊粉层细胞壁越厚的样品其体内含水量越高且水分子的移动性越好。因此,小麦糊粉层细胞壁结构对水分迁移具有显著调控作用。     

小麦糊粉层结构及特性研究进展

小麦是人们日常生活不可或缺的粮食作物,小麦糊粉层则聚集了小麦籽粒大部分的营养与精华。糊粉层不仅在小麦籽粒发育时起着重要作用,更是对人体健康有着极大的益处。对糊粉层的营养组成进行介绍,并对糊粉层的生理结构、功能特性及对食品影响等几个方面进行概述。     

微生物细胞壁结构及结合真菌毒素的研究进展

生物去除真菌毒素是目前的研究热点之一。除了微生物产酶对毒素进行化学修饰后降解为无毒或者毒性较低的产物外,微生物细胞对毒素的吸附与结合作用也占有一定的比例,这与微生物表面组成和结构特征相关。本文就微生物细胞表面结构及吸附毒素的国外研究进展进行概述,重点阐述相关研究现状、黏附机理和影响因素,旨在为真菌毒素的去除研究提供参考。     

小麦糊粉层分离及产品开发研究进展

小麦中大部分的生物活性物质多聚集于糊粉层中,主要论述了小麦糊粉层的组成、分离技术、相关产品研究。大力开发糊粉层产品,能够改善人们的营养结构,促进民众健康水平,提升粮食利用率、延长小麦产业链。对小麦糊粉层的研究和开发利用,使其能够广泛应用于食品工业中。     

英国的小麦剥皮制粉工艺

本文介绍一种被称之为Trigotec的英国小麦剥皮制粉工艺。应用该工艺可提高小麦的精制粉和麦心出率,同时产生的副产品也不同于传统工艺的。它品种较多,每一种副产品在营养利用方面都有其专门的用途。     

小麦籽实糊粉层与面粉品质的关系

本文从小麦籽实糊粉层细胞组织具有丰富的营养成分方面进行了分析；对改良和强化优质面粉烘焙品质及保持天然营养成分进行了科学的论证。     

小麦籽实的形态结构与制粉方法的配合

配合小麦籽实的三大组成部分──籽实皮、胚乳和胚的形态和结构，进行解剖型模式制粉方法改革，是合理利用小麦资源的一条重要途径。     

保加利亚乳杆菌细胞壁蛋白酶基因克隆及结构分析

本文以保加利亚乳杆菌基因组为模板,利用PCR的方法扩增细胞壁蛋白酶基因(prtB),并且利用GeneBank数据库和生物软件对prtB进行对比和生物信息学分析,预测基因片段的相似性、表达出蛋白酶的蛋白大小、二级结构和膜结合性等性质。结果表明,测序后比对发现扩增片段与模板保加利亚乳杆菌prtB相似性为100%,证明基因片段未发生突变;prtB与德氏乳杆菌德氏亚种基因相似性为96%,与德氏乳杆菌乳酸亚种(Lactobacillus delbrueckii)基因相似性为82%,具有一定的保守性和特异性。prtB基因G+C含量为47.49%,A+T含量为52.51%,编码1831个氨基酸,分子量为3338.7 kD,将此蛋白命名为PrtB,等电点pI为8.76。保加利亚乳杆菌的PrtB为亲水性稳定蛋白,总平均亲水性为-0.583,有28个Ser、9个Thr和25个Tyr可能成为蛋白激酶磷酸化的作用位点,该蛋白为细胞外蛋白,其二级结构以不规则卷曲为主,其值为55.11%,α-螺旋和β-折叠仅占21.30%和23.59%。     

把握小麦价格因素，调控粮食价格

通过考察20世纪80年代以来中国小麦价格的历史演进.特别是20世纪90年代以来多种因素对粮食的影响,全面考察影响小麦的价格因素,得出影响粮食价格的关键因素.通过对小麦市场的考察,为粮食市场的价格预测,国家的粮食价格调控提供参考.     

分离小麦糊粉层的生产线设计

介绍了一种机械分离小麦麸皮糊粉层的工艺及控制指标。该工艺投资少,生产周期短,便于规模化生产,安全卫生,能保持小麦麸皮糊粉的营养特性。     

ENZYME DEVELOPMENT IN THE ALEURONE AND EMBRYOS OF GALANT AND TRIUMPH BARLEYS

The aleurone layer of the pro-anthocyanidin free barley, galant, produced less endo-beta-(1–3, 1–4) glucanase and alpha-amylase than the aleurone of triumph. The slower rate of endosperm breakdown (modification) of galant is associated with its reduced potential to produce the cell-wall-degrading enzyme, endo-beta-(1–3, 1–4) glucanase.     

Preparation and characterisation of arabinoxylan and (1,3)(1,4)-β-glucan alternating multilayer edible films simulated those of wheat grain aleurone cell wall

Various observations show a lamellar organisation of wheat aleurone cell walls, that likely acted as barriers to regulate the water diffusion rate in wheat grains. In this study, arabinoxylan (AX) and (1,3)(1,4)-β-glucan (BG) alternating multilayer films which mimic cell wall of aleurone structure were prepared. Twenty layers of alternating multilayer films of AX/BG were prepared with individual thicknesses of 20 µm. The water diffusion and water mobility of the films were determined using dynamic vapour sorption and time-domain nuclear magnetic resonance spectroscopy. The AX/BG alternating multilayer films exhibited unique mechanical and hydration properties, which could be explained by their unique nanostructure and microporosity. The edible films with this structure were found to exhibit high ultimate stress and ultimate strain, and low rates of water diffusion.     

The glucanase-soluble mannoproteins limit cell wall porosity in Saccharomyces cerevisiae

The cell wall porosity of batch-grown Saccharomyces cerevisiae was maximal in the early exponential phase and fell off rapidly to lower levels in later growth phases. Treatment of stationary-phase cells with alpha-mannosidase restored wall porosity to the level of cells in early exponential phase. When cells in the early exponential phase were treated with alpha-mannosidase, or tunicamycin, an inhibitor of N-glycosylation, even higher porosities were obtained. Mutants with truncated mannan side-chains in their wall proteins also had very porous walls. The importance of the mannan side-chains for wall porosity was also seen during sexual induction. Treatment with alpha pheromone, which leads to the formation of wall proteins with shorter mannan side-chains, enhanced wall porosity. Disulphide bridges also affect cell wall porosity. They were predominantly found in the glucanase-soluble wall proteins. Because the main part of the mannan side-chains is also found in this family of wall proteins, our results demonstrate that the glucanase-soluble mannoproteins limit cell wall porosity in yeast.     

The influence of the sequential extractions on the structure and the properties of single cell materials from apples

In order to evaluate the influence of disintegration on the structure and the properties of single cell wall materials from apples, parenchymatic single cells (MM) were extracted step by step with water (BM), chelating agents (CH), sodium chlorite/acetic acid mixture (CO) and sodium hydroxide/NaBH₄ (CA). The composition and the structure parameters of the dried materials obtained showed enhanced cell wall disintegration in the order MM, BM, CH, CO and CA. This disintegration was proved by decreasing yields and increasing glucose contents indicating a lower share of amorphous matrix and a higher share of cellulose-xyloglucan network with rising steps of the sequential extraction. However, systematic alterations of galacturonan content, bulk density, solid density and porosity with increasing cell wall disintegration were not found. The hydration properties, determined as swelling and water retention capacities, decreased in the order BM, MMCO, CH and CA. Also, the structure-viscous and viscoelastic properties of the rehydrated CWM in the decreasing order CH, CO, BM, MM and CA were not in agreement with the order of the cell wall disintegration as well as with the order of the hydration properties. The results show a complex and multivariate correlation between structure, physical state and properties.     

A protein which masks galactose receptor mediated phage susceptibility in Lactococcus lactis subsp. lactis MPL56

A 28.5-kb plasmid, isolated from Lactococcus lactis subsp. lactis MPL56, causes complete inhibition of four lactococcal phages. Cell wall characteristics of wild-type strain MPL56 were compared with its 28.5 kb plasmid-cured, phage-sensitive derivative MPL56-22. After proteolytic enzyme treatments, adsorption of phages occurred at high levels, an example is 94.6–98.5% in MPL56 cells. Analysis of cell wall extracts of MPL56-22 by sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS–PAGE) indicated that the only difference between strains was the 55.4 kDa band in protein patterns of MPL56. Adsorption of the four phages was completely inhibited when MPL56-22 cells were subjected to SDS, Triton-X-100, HCl and NaOH treatments. Lectins that were specific for glucose/mannose and N-acetylglucosamine did not prevent adsorption of phages in cell wall extracts of MPL 56-22. However a lectin specific for galactose (MCA; Momordica charantia ) completely inhibited adsorption of these phages in cell wall extracts of MPL56-22. HPLC patterns of cell wall carbohydrates of MPL56-22 and its HCl treated preparations showed that the most prevalent difference was the galactose on untreated MPL56-22 cell wall chromatograms.     

雨生红球藻物理破壁法提取虾青素研究

研究了几种常用的物理破壁法对雨生红球藻厚壁孢子细胞破壁率及虾青素提取率的影响,确定了高压均质处理、超声波法和反复冻融法的最适工艺条件。试验结果表明:高压均质处理最适合于雨生红球藻厚壁孢子的破碎和虾青素的提取。高压均质的优化条件为:40MPa,室温,循环3次,破壁率可达91.4%,虾青素提取率为28.02μg/mg(细胞干重),而未经破壁的虾青素提取率仅为17.92μg/mg(细胞干重),提取率提高了56.3%。