Stability of Bacterial alpha-Amylase in the Starch Liquefaction Process

Nowadays, starch is normally liquefied by an all enzymatic process at a high temperature. In 1973 a new α-amylase was introduced which was more heat-stable than the products so far used. It is produced by a strain of Bacillus licheniformis. Since then, this enzyme has been recommended for use in a single dosagejet cooking process, operating at 105 °C for a few min followed by a 90–95 °C dextrinization period. This process is easy and energywise more economic than earlier processes. This lecture deals with the stability of this enzyme, depending on: Temperature, pH, starch dry substance and salt content. A formula for the calculation of stability is given, as a function of these parameters. The degree of hydrolysis, very often measured as Dextrose Equivalent (DE), can for a given process be estimated also by a formula. Results from pilot plant trials confirming the laboratory investigations are presented. Based on the stability data it is possible to estimate optimum design parameters for the use of this enzyme in individual processes, thus minimizing enzyme cost.     

In vitro Digestion of Hydroxypropyl Derivatives of Wheat Starch. I. Digestibility and Action Pattern Using Porcine Pancreatic alpha-Amylase

The digestion by Porcine Pancreatic α-Amylase (PPA) of a number of laboratory prepared hydroxypropyl wheat starches was examined. For the gelatinized starches, digestibility decreased, and the action pattern of the enzyme tended to favour non-repetitive attack, as degree of substitution increased. In the case of the raw starches digestibility increased with extent of modification. The reaction conditions used to prepare the modified starches had little effect on the digestibility of the gelatinized starch but caused some increase in that of the raw material.     

漂白麦草浆细杂组份对阳离子淀粉吸附的影响

本文研究了漂白麦草浆中细杂组份(通过100目,其中大部分是杂细胞,如薄壁细胞,表皮细胞)对阳离子淀粉吸附的影响。 实验表明,漂白麦草浆中细杂组份的比表面积明显大于纤维组份(保留在100目以上)的比表面积。阳离子淀粉优先吸附在比表面积大的细杂组份上。纤维组份的吸附能力受化学环境的影响较细杂组份更为敏感。     

Characterization of Resistant Starch from Autoclaved Wheat Starch

The nature of a particular type of in vitro undigestible starch, i.e. resistant starch (RS), was studied. This type of undigestible starch is found in products processed at relatively high moisture contents, such as baking and autoclaving. The RS was concentrated by enzymic digestion of available starch and protein and recovered by centrifugation. RS from autoclaved wheat starch was evaluated by various methods. The crystallinity was studied by X-ray diffraction and DSC. The degree of polymerization (DP) was evaluated with gel permeation chromatography and iodine binding and the starch content and linearity by enzymic methods. The results indicate that RS consist of crystallized, linear α-glucans of relatively low molecular weight (DP approx. 65). The recovery of RS after various drying procedures, and the introduction of a thermostable amylase (Termamyl®) in the RS assay was also studied. Oven-drying of the fibre residues used in the analysis had no significant effect on RS recovery, whereas freeze-drying was accompanied by a slight increase in RS content. The use of Termamyl®, in the assay of RS in the fibre residues, decreased the yield of RS by 10–15%.     

小麦交联淀粉的制备工艺研究

采用环氧氯丙烷为交联剂，以小麦淀粉为原料制备小麦交联淀粉。探讨了环氧氯丙烷用量，氢氧化钠用量，反应温度，反应时间对交联度的影响并利用design-expert6.0.3软件响应面中心组合实验优化得出制备不同交联淀粉的最佳工艺条件，分析了双因素间的交互效应。     

Alkali Gelatinisation of Wheat Starch

Alkali gelatinisation of wheat starch was found to depend on starch and alkali concentration and was faster at higher temperatures and higher alkali/starch ratios. Viscosity of an alkaline starch slurry continued to increase after both in vitro digestibility and soluble amylose reached maximum values. Despite extensive granule swelling, deformation and bursting, birefringence was retained to some degree indicating differences in mechanism between alkali and heat gelatinisation.     

In vitro Digestion of Hydroxypropyl Derivatives of Wheat Starch. II. Effect of Substitution on the Products of Partial Digestion by Porcine Pancreatic alpha-Amylase

The hydrolysates obtained after partial digestion, by porcine pancreatic α-amylase, of laboratory prepared hydroxypropyl wheat starches (DS 0-0.17) were separated into total digest, oligosaccharide and polysaccharide fractions. These fractions were analysed for blue value, reducing value, total carbohydrate and hydroxypropyl group content. It was found that increasing DS caused a decrease in reducing value, an increase in average degree of polymerisation and a greater proportion of oligosaccharide in the hydrolysate. The oligosaccharide fraction contained most of the modifying groups in the total digest and had approximately double the hydroxypropyl content of the undigested starch.     

国内优质小麦淀粉特性研究

为保持小麦淀粉天然特性,发展一种通过直接破碎浸泡过的小麦籽粒分离淀粉的方法,然后对所得十九种国内优质小麦的淀粉的蛋白质、脂肪、直链淀粉、水分含量及白度进行测定,通过比较、分析,总结得出不同品种小麦淀粉特性。     

Wheat Starch Modification Through Biotechnology

Natural mutations that affect the amylose/amylopectin ratio in starch are unlikely to develop naturally in wheat due to its allohexaploid genome (2n=6x; AABBDD). One of the strategies to modify wheat starch structure involves identification of germplasms with null alleles for starch biosynthetic genes, followed by exchange of functional alleles with the identified null alleles through classical plant breeding. This technique has successfully been used to combine the three null alleles for granule-bound starch synthase I (GBSSI) to develop a wheat line that produces amylopectin-rich (>95%) starch (waxy starch). Another strategy to alter expression levels of starch biosynthetic genes employs recent advances in molecular biology and genetic engineering of wheat. For this approach, various monocot vectors have been developed that drive expression of wheat starch branching enzyme I (SBEI) cDNA sequences in the anti-sense orientation. Several of the wheat cell lines transformed with the anti-sense vectors express branching enzyme (BE) activity at a significantly lower level than non-transformed cells. One transgenic wheat plant expressing the anti-sense SBEI RNA produces a ten-fold lower level of BE activity in kernels than wild-type wheat. Analysis of starch produced from the transgenic plant shows that starch structure and properties have been altered.     

面筋淀粉分离机与小麦淀粉工艺技术研究

现有的面筋淀粉分离机有MJ面筋机,它采用马丁法工艺;旋流器采用水力旋流工艺;三相卧螺分离机的工艺复杂、能耗大。改进后的面筋机可实现连续化流水作业,减轻人工劳动强度,提高劳动生产力、增强面筋淀粉分离效果,与引进设备相比,工艺简捷,能耗降低,可以实现远程监控。     

Inherent Variation in Wheat Starch Pasting due to Cultivar

Starches isolated from 59 wheat cultivars, of diverse genetic origin but grown in New Zealand, exhibited hot-pasting peak viscosities ranging from 82 to 269 units when tested by ‘Minipaster’. Each starch was prepared without mechanical damage, without drying, and was pasted at 10% db concentration in the absence of amylase, with pH adjusted to 5.5 before pasting. Two small groups of cultivars were distinguished on the basis of unusual pasting properties, having either high peak viscosity relative to both breakdown and setback viscosities, or high setback viscosity relative to both peak and breakdown viscosities.     

提高浸出大豆油维生素E含量与氧化稳定性方法简介

研究表明，大豆油中维生素E（VE）含量与大豆贮存、加工过程中的各种条件密切相关，其中主要因素是大豆水分及温度对大豆中脂质过氧化酶、磷脂酶D的活性有很大影响，而这两种酶的活性对浸出大豆中非水化磷脂含量、VE含量、FFA氧化稳定性有着极大影响。因此，在大豆加工过程中采用适当工艺条件破坏这两种酶的活性使其钝化的各种方法，将有助于提高大豆油中VE含量与氧化稳定性。同时，也有利于减少浸出毛油中非水化磷脂含量，不仅可降低炼耗，而且，对于防止精炼大豆油回色与气味劣变有效。本文简要介绍了国外油脂工作者采用的几种大豆预…     

Retrogradation of Starch in Cooked Wheat

Retrogradation phenomenon in cooked wheat grain was investigated by means of Differential Scanning Calorimetry (DSC) and mechanical compression tests. The extent of starch retrogradation as measured by endotherm increased with time. More importantly, the onset, peak and conclusion temperatures are dependent on the storage temperature and are significantly lower for grain stored at lower temperatures. The firmness of the grain due to starch crystallization as indicated by the elastic modulus also increased with time and was higher at lower storage temperatures. Lowered storage temperature not only accelerates starch recrystallization and thus firming process of the cooked grain, but also seems to generate a different organization in the ordering of the starch.     

小麦淀粉特性的探讨

逐一分析了小麦淀粉的结构、组成、糊化特性、黏度参数与面条品质、膨胀势等性状的关系,提出面条品质改良,与小麦糊化特性紧密相关,不仅考虑蛋白质品质,同时也要重视淀粉特性的影响。     

青稞淀粉和小麦淀粉的理化性质比较研究

研究了青稞淀粉的理化性质,包括淀粉的颗粒形态、粒度分布及淀粉糊透明度、溶解度、膨胀力和糊化特性,并与小麦淀粉性质进行比较。结果表明:青稞淀粉颗粒的平均粒径大于小麦淀粉颗粒的平均粒径,青稞淀粉颗粒大小和形状分布均匀;青稞淀粉糊透明度大于小麦淀粉糊,但在储藏过程中,青稞淀粉糊透光率变化显著;青稞淀粉的溶解度和膨胀力均大于小麦淀粉糊,这与小麦淀粉中小颗粒淀粉含量较多有关;与小麦淀粉的糊化相比,青稞淀粉成糊温度低,糊化容易,但峰值黏度低,衰减值大,热糊稳定性差,回生值大,冷糊稳定性差,易老化。     

多孔玉米淀粉吸附氨茶碱药物的研究

用真茵淀粉酶酶解制成多孔玉米淀粉,研究探讨了以其作为药物栽体吸附氨茶碱的性能,并建立了一种特殊的紫外分光光度测定多孔淀粉吸附氨茶碱量的方法.多孔淀粉吸附氨茶碱的最佳条件是氨荼碱初始浓度40mg/mL,温度20℃,时间为60min, pH 9.5,在此条件下,吸附量达到79.26mg/g,比原淀粉的吸附能力提高了3.1倍.     

小麦淀粉品质的研究

测定了河南省22个小麦品种（样品）的籽粒蛋白质、淀粉与直链淀粉含量,并采用快速粘度分析（RVA）测定了这些品种的面粉湖化特性。参照国内外研究结果综合鉴评认为：在供试的小麦品种中,温6（稻茬）、豫麦47、郑农7号、豫麦52、百农64、周麦12等具有适于制作优质面务的淀粉品质;同时观察到同一品种在不同种植条件下,其蛋白质含量、直链淀粉含量和淀粉品质有很大差异。进一步证明了在优质小麦生产中选择适宜种植地区和采用适宜栽培技术的重要性。     

小麦淀粉品质的研究

测定了河南省22个小麦品种(样品)的籽粒蛋白质、淀粉与直链淀粉含量,并采用快速粘度分析(RVA)测定了这些品种的面粉糊化特性.参照国内外研究结果综合鉴评认为在供试的小麦品种中,温6(稻茬)、豫麦47、郑农7号、豫麦52、百农64、周麦12等具有适于制作优质面条的淀粉品质;同时观察到同一品种在不同种植条件下,其蛋白质含量、直链淀粉含量和淀粉品质有很大差异.进一步证明了在优质小麦生产中选择适宜种植地区和采用适宜栽培技术的重要性.