Comparison Between Granular Starch Hydrolyzing Enzyme and Conventional Enzymes for Ethanol Production from Maize Starch with Different Amylose: Amylopectin Ratios

The effect of enzyme treatments (granular starch hydrolyzing and conventional enzymes) and different amylose: amylopectin ratios of maize starch on ethanol production was evaluated. For starch treatments, amylose: amylopectin ratios were prepared by mixing commercially available Hylon VII (70% amylose and 30% amylopectin) and Amioca (˜100% amylopectin) starches. For maize treatments, waxy, high amylose and regular dent hybrids were used to represent varying amylose: amylopectin ratios. All hydrolyses followed by fermentations were conducted at 15% solids content. Differences were observed in ethanol yields among granular starch hydrolyzing and conventional enzymes. Differences also were observed in ethanol yields between different amylose: amylopectin ratios for pure starch and maize samples. For starch samples, final ethanol concentrations varied from 2.2 to 9.1% (v/v) for fermentation with granular starch hydrolyzing enzyme and from 6.7 to 9.3% (v/v) for conventional enzymes. Higher ethanol concentrations were observed for Amioca starch for both enzymes. For maize samples, final ethanol concentrations were highest for waxy maize for both granular starch hydrolyzing (8.2%, v/v) and conventional (8.2%, v/v) enzymes. Lowest ethanol concentrations were observed for high‐amylose maize samples for granular starch hydrolyzing (6.3%, v/v) and conventional (5.2%, v/v) enzymes.     

酶水解法测定玉米中淀粉含量方法的探讨

玉米中淀粉含量的测定方法有很多,GB/T 5514—2008标准中规定采用酶水解法对玉米中的淀粉含量进行测定,但该方法存在结果偏低、偏差较大的缺点。本实验对标准中的实验方法及相关条件,如玉米称样量、加水量、液化酶用量、液化温度、液化时间、水浴条件、过滤方式、加酸量等,进行了优化并对实验中存在的问题进行了分析和探讨,优化后的方法适合玉米中淀粉含量的测定,具有实用、准确、稳定性好的特点。     

响应面试验优化玉米淀粉挤出-酶解复合法糖化工艺

以经过挤出-酶解复合法液化后的玉米淀粉为原料,利用葡萄糖淀粉酶为糖化酶,采用挤出-酶解复合法糖化玉米淀粉挤出酶解物。以葡萄糖(dextrose equivalent,DE)值为考察指标,在单因素试验的基础上,利用响应面法对糖化工艺参数进行优化,确定最佳挤出工艺。响应面分析结果表明,最优工艺为葡萄糖淀粉酶添加量140 U/g、原料质量分数70%、挤出温度85℃,由此工艺得到的淀粉糖DE值为42.12%。利用高效液相色谱法检测得出DE38产品葡萄糖含量26.17%、麦芽糖含量25.29%、麦芽三糖含量14.86%,DE42产品葡萄糖含量29.57%、麦芽糖含量33.40%、麦芽三糖含量17.23%。红外图谱显示挤出物中含有葡萄糖等低聚糖特征峰,扫面电镜图显示原料经挤出后表面生成多孔状结构,X-射线衍射图显示有新的晶型结构生成,Brabender黏度曲线表明挤出物中含有小分子可溶性糖,黏度降低。     

响应面试验优化挤出酶解复合法改性玉米淀粉工艺

利用挤出酶解对玉米淀粉进行改性,采用响应面法对影响改性工艺的主要因素耐高温α-淀粉酶添加量、挤出温度、玉米淀粉含量进行优化,通过高效液相色谱、扫描电子显微镜、X-射线衍射以及差示扫描量热仪对玉米淀粉挤出酶解复合改性前后的低聚糖组成、表观结构、结晶度以及热力学性质的变化进行分析。结果表明：当耐高温α-淀粉酶添加量40 U/g、挤出温度140 ℃、玉米淀粉含量70%时,挤出改性玉米淀粉葡萄糖当量值为19.55%。高效液相色谱分析表明挤出物低聚糖的组分能够得到较好的分离,低聚糖样品中各组分葡萄糖、麦芽糖、麦芽三糖、麦芽四糖、麦芽五糖的质量比为1.0∶3.4∶7.5∶6.0∶1.8。玉米淀粉经挤出酶解复合改性后颗粒表面出现孔洞,结晶度下降。     

酶预处理和酸水解制备糯玉米淀粉纳米晶及其表征

采用糖化酶对糯玉米原淀粉进行预处理,通过X射线衍射(XRD)确定糖化酶预处理的最佳用量,再对酶预处理淀粉进行硫酸酸水解,制备糯玉米淀粉纳米晶,采用傅里叶变换红外光谱（FT-IR）、扫描电子显微镜(SEM)、粒径测量和Zeta电位分析等对淀粉纳米晶进行表征。结果表明,用1000U/(g淀粉)活性的糖化酶对糯玉米原淀粉处理2h,再结合酸水解2天,得到粒径约100nm、分散性好、产率为24.1%的糯玉米淀粉纳米晶;相较于仅硫酸酸水解处理,酶预处理结合酸水解法制备糯玉米淀粉纳米晶的反应时间缩短了3天,产率提高了70.9%,淀粉纳米晶的Zeta电位达-22.3 mV。     

干法制备玉米淀粉磷酸酯

采用单因素试验结合正交试验对食品用玉米淀粉磷酸酯的干法制备进行可行性研究。该工艺旨在解决传统湿法制备时,需洗涤和干燥,以及由此引起的环境污染及高能耗问题。通过控制三聚磷酸钠添加量使反应体系中总磷含量低于0.4%(干基),反应后可不进行洗涤和干燥,直接得到成品。在单因素试验基础上,通过正交试验确定生产最佳工艺条件为:三聚磷酸钠0.4%(干基)、固相酯化温度130℃、固相酯化时间3 h、反应体系pH 6.89。将干法制得产品与湿法生产玉米淀粉磷酸酯进行比较,在取代度(degree of substitution,DS)、pH、糊透明度和冻融稳定性方面性质较为接近。     

Effects of Ultra High Pressure,Pressing Time and HCl Concentration on Non‐thermal Starch Hydrolysis Using Ultra High Pressure

Effects of ultra high pressure (UHP), pressing time and HCl concentration on non‐thermal starch hydrolysis using ultra high pressure were investigated. As regards ultra high pressure, starch granules maintained their structure up to 450 MPa and were partially disintegrated at 600 MPa. Degree of hydrolysis did not change up to 450 MPa and dramatically increased at 600 MPa indicating that starch hydrolysis increased with increasing destruction of starch granules. Pressing time did not affect the degree of hydrolysis. However, degree of hydrolysis and destruction of starch granules increased with increasing HCl concentration up to 4 M. Gel permeation chromatography showed that the soluble fraction of starch formed by hydrolysis mainly consisted of maltooligomers and maltose. X‐ray diffraction pattern changed from A type to C type upon hydrolysis, otherwise it remained as A type. This work provides fundamental information of UHP processing for starch and shows a potential of non‐thermal UHP processing for a new starch hydrolysis method.     

非晶颗粒态玉米淀粉理化性质及消化性能的研究

非晶颗粒态淀粉是一种特殊的淀粉物态形式,具有颗粒性,但不具有结晶性。为了实现对原淀粉颗粒的改性,本文以玉米淀粉为原料,采用乙醇溶液处理法制备非晶颗粒态淀粉。在此基础上,研究了这种非晶化处理方法对玉米淀粉的颗粒形貌、结晶性质、溶解度与膨胀力及体外消化性能的影响。结果表明,原淀粉经非晶化处理后颗粒性仍保持完整,但颗粒表面有较大爆裂孔生成,并出现明显褶皱;非晶颗粒态玉米淀粉呈现V-型衍射结构,其结晶性基本消失,颗粒由多晶颗粒态结构转变为非晶颗粒态结构;与玉米原淀粉相比,其溶解度和膨胀度在相同的测定温度下均明显增加。原淀粉经乙醇溶液处理后,其快消化淀粉含量由92.83%下降到81.64%。而慢消化淀粉和抗性淀粉总含量由7.17%上升到18.36%。因此,采用乙醇溶液处理法对淀粉颗粒进行改性将有助于开发低热量和慢血糖应答的产品。     

Degradability of Different Phosphorylated Starches and Thermoplastic Films Prepared from Corn Starch Phosphomonoesters

Different starch types (corn, rice, potato, corn amylose and corn amylopectin) were phosphorylated to varying degrees of substitution (DS) and tested both for acid hydrolysis during 3 h in a boiling bath and for enzymatic hydrolysis with a thermostable bacterial α‐amylase (Bacillus licheniformis) for 30 min at 95 °C. Generally, phosphorylated starches showed a reduced degree of acid hydrolysis during the entire time of hydrolysis (3 h) as well as reduced susceptibility to α‐amyIase hydrolysis. The enzyme action was inhibited by the presence of phosphate groups in the modified starch molecules and the extent of inhibition increased with increasing degree of phosphate substitution, regardless of the starch type. Thermoplastic films were fabricated by blending modified corn starches of different DS with polyacrylate, urea and water at a ratio of 4:5:1:50, heating for 30 min at 95 °C before casting and allowing to cool, stand and dry at room temperature. The plastic films prepared from phosphorylated corn starch showed both higher disintegration rate and a greater degradability by thermostable bacterial α‐amylase than the ones prepared from non‐phosphorylated starch. These new acquired properties can meet the increasing demand for biodegradable disposable plastic bags.     

Effect of Enzymatic Hydrolysis of Wheat Starch on Amylose‐Lipid Complexes Stability

In the process of enzymatic hydrolysis of wheat starch to glucose, the presence of amylose‐lipid complexes (AML's) decreases swelling and dissolving capacity and the water binding capacity of starch, thus impeding the access of amylolytic enzymes to the starch granules. The aim of the work was to define the relationship between the stability of AML's and the conditions of the enzymatic hydrolysis of wheat starch such as the kind of enzymatic preparation (only amylolytic or both amylolytic and lipolytic) and time of hydrolysis. Hydrolysates were produced from wheat starch liquefied with bacterial α‐amylase BAN 240L, subjected to further treatment with the enzymatic preparation Spezyme GA 300W, containing glucoamylase and lysophospholipase and, for comparison, only with a glucoamylase preparation (AMG 300L). The effect of amylolytic and lipolytic enzymes on the stability of AML's in the process of wheat starch hydrolysis was estimated. The amount of fatty acids released during hydrolysis was determined with gas‐liquid chromatography (GLC) and by differential scanning calorimetry (DSC) measuring the enthalpy of decomposition of AML's. The investigations revealed a differentiated effect of the individual enzymatic preparations on the degree of degradation of AML's. Amylose‐lipid complexes were more susceptible to the attack of preparation Spezyme GA 300W than to the digestion by α‐amylase BAN 240 L and glucoamylase AMG 300L.     

在乙酸缓冲液中用复合酶水解淀粉的工艺条件研究

研究了在乙酸-乙酸钠缓冲液中用复合酶(淀粉酶/糖化酶)水解玉米淀粉的工艺条件,对影响水解液DE值的主要因素进行了探讨. 结果表明,影响DE值的主要因素依次为温度、pH值、酶比例(α-淀粉酶:糖化酶)、时间.通过正交实验得到优化工艺条件为:酶比例为1:4,温度为60℃,pH值为4. 0,时间4h.在优化条件下,水解液DE值为64. 21.     

玉米淀粉乳液在B级生活用纸中的工艺实践

将玉米淀粉按比例混合,制备成玉米淀粉乳液,作为造纸湿部添加剂加入纸浆中,可增强纤维之间的连接,具有稳定纸张纹路作用,能够显著提高原纸的物理性能.该文就玉米淀粉乳液在B级生活用纸中的工艺实践与应用作了介绍.     

The Relationship Between Wheat Flour and Starch Pasting Properties and Starch Hydrolysis: Effect of Non‐starch Polysaccharides in a Starch Gel System

Non‐starch polysaccharides (NSPs) and celite (used as inert filler) were incorporated into wheat flour and wheat starch paste preparations at levels of 1, 2.5, and 5% in both addition and replacement modes. Pasting properties of gums were compared using a Rapid Visco Analyser. Use of guar gum and locust bean gum elevated the peak and final viscosities of the resulting pastes (when used in either addition or replacement modes), whereas arabic gum significantly reduced the peak and final viscosity properties of the pastes. Samples which comprised wheat starch yielded higher peak and final viscosity characteristics compared to wheat flour containing samples, however higher breakdown and setback values were observed for samples using wheat flour as a base compared to wheat starch. The firmness of the gels (as determined using a texture analyser) increased with the use of wheat starch compared to wheat flour. Little significant difference was observed between NSP used and mode of application (replacement or addition). In vitro starch degradation was conducted on the wheat flour gels. Guar gum and locust bean gum reduced the amount of starch degradation in these gels, whereas arabic gum and celite increased the amount of starch hydrolysis (or were similar to the control). The rate of starch hydrolysis appears to be related to the viscosity altering behaviour of the NSPs in a starch‐rich system. The results indicate that selection of NSPs is important as gum arabic has the potential to increase starch hydrolysis compared to the control.     

A Rapid In‐vitro Digestibility Assay Based on Glucometry for Investigating Kinetics of Starch Digestion

The potential of glucometry in in‐vitro starch digestion was investigated for developing a rapid procedure to understand kinetics of digestion. A hand‐held glucometer, intended for testing of plasma glucose levels, was used for the assay of glucose released by the combined action of α‐amylase and amyloglucosidase on a range of starch substrates. The glucometer was sensitive to glucose concentrations in water, and its readings were independent of pH (7.7 and 3.9) and temperature (37°C and 25°C) of the glucose solution, but dependent on lactose and maltose concentrations. Neither fructose nor sucrose affected the readings. Digested starch calculated from the glucometer was not significantly (p > 0.05) different from that calculated from spectrophotometry. Particle size of substrate, sample formulation, grain genotype, and processing affected the glucometer readings as expected from how these factors influence starch digestibility. Corrections are required when samples containing lactose and maltose prior to in‐vitro digestion analysis are studied. The developed rapid procedure can be used to collect large numbers of data points per sample per analysis for better understanding the kinetics of starch digestion, and increased confidence level in modelling the digestogram. The glucose detection method is robust and could be adapted for non‐laboratory use. Single‐point data can also be extracted from digestograms for comparative analysis.     

Physicochemical Properties of Non‐thermally Cross‐linked Corn Starch with Phosphorus Oxychloride using Ultra High Pressure (UHP)

Corn starch (20%, w/w) was non‐thermally and conventionally cross‐linked with phosphorus oxychloride (POCl₃; 0.01, 0.05, or 0.1%, based on dry weight of starch) at 400 MPa for 5, 15 and 30 min and at 45°C for 2 h, respectively. Swelling power and solubility of both non‐thermally and conventionally cross‐linked corn starches were relatively lower than those of native corn starch. The pressure holding time did not affect the solubility and swelling power of non‐thermally cross‐linked corn starches. X‐ray diffraction patterns and relative crystallinity were not significantly altered by both conventional and non‐thermal cross‐linking. DSC thermal characteristics of both non‐thermally and conventionally cross‐linked corn starches were not significantly changed indicating that the double helical structure of amylopectin was not influenced by both conventional and non‐thermal cross‐linking reactions. Both non‐thermal and conventional cross‐linking greatly affected the Rapid Visco Analyser (RVA) pasting properties, such as increase in pasting temperature and decrease in peak viscosity compared to native starch. This result suggests that in case of cross‐linking using POCl₃, both non‐thermal and conventional methods result in similar physicochemical properties and non‐thermal cross‐linking with POCl₃ can reduce the reaction time from 2 h to 15 min. This work shows the potential and possibility of non‐thermal starch modification and provides the basic and scientific information on the physicochemical properties of non‐thermally cross‐linked corn starches with phosphorus oxychloride using UHP.     

Effect of Raw and Heat‐Moisture Treated High‐Amylose Corn Starch on Fermentation by the Rat Cecal Bacteria

Resistant starch content of high‐amylose corn starch (HAS) was doubled by heat‐moisture treatment. Resistant starch content of HAS and heat‐moisture treated high‐amylose corn starch (HMT‐HAS) were 31.8 and 67.3%, respectively, as determined by enzymatic‐gravimetric method. Effects of the two types of high‐amylose corn starches, HAS and HMT‐HAS, on starch fermentation, microflora, pH, short chain fatty acid (SCFA) content and β‐glucuronidase activity in the cecal content have been investigated. Rats were given ordinary corn starch (OCS; control), HAS or HMT‐HAS at 10% level for 10 13 days. The cecal and colorectal content s weights were larger in HAS and HMT‐HAS groups than in the OCS group. The cecal content s weight did not differ between HAS and HMT‐HAS groups, while the colorectal content s weight was higher in the HMT‐HAS group than in the HAS group. The upper and lower small intestinal and cecal starch contents were significantly higher in the HAS and HMT‐HAS groups than in the OCS group, whereas there were no differences between colorectal starch content in group OCS and HAS. Starch excretion in feces was significantly higher in groups HAS and HMT‐HAS than in group OCS, the increase in the HMT‐HAS group was especially remarkable. The composition of the cecal microflora was not effected by the diet. β‐Glucuronidase activities in rats fed HAS or HMT‐HAS decreased. SCFA concentration was higher in groups HAS and HMT‐HAS than in group OCS, and the cecal pH was lower in groups HAS and HMT‐HAS than in group OCS.     

Preparation of oxidized corn starch in a screw extruder under alkali‐free conditions

To promote water solubility of oxidized starch prepared by the dry process, a twin screw extruder was used as a reactor in the present study. Through single‐factor experiments and orthogonal experiment, the effects of barrel temperature, moisture content, addition amount of NaOCl, and screw speed on the carboxyl content (CC) and water solubility index (WSI) of oxidized corn starch were investigated. The results indicated that high screw speed, medium barrel temperature, and low moisture content could lead to high WSI of oxidized corn starch produced by extrusion. The reaction efficiency and solubility of oxidized starch prepared by reactive extrusion under the optimal condition were all improved greatly, especially the WSI was very high (99.56%). Preparation of oxidized starch by reactive extrusion under alkali‐free conditions could be described as a rapid (only several minutes), continuous, reduced addition amount of NaOCl, eco‐friendly new dry technology.     

微波法制备羟丙基多孔玉米淀粉工艺优化

采用微波法对玉米多孔淀粉原料进行处理,经过正交试验优化工艺,制备具有不同取代度的羟丙基玉米多孔淀粉。研究在微波作用下,淀粉乳质量分数、微波处理时间、微波功率以及环氧丙烷用量对产品取代度的影响。结果表明,用微波法制备羟丙基玉米多孔淀粉的最佳反应条件为微波功率300W、环氧丙烷用量(质量分数)6.90%、微波时间3min、淀粉乳质量分数30%,在该条件下制备的羟丙基多孔淀粉的摩尔取代度为0.0103。     

Influence of Selected Parameters of Starch Gelatinization and Hydrolysis on Stability of Amylose‐Lipid Complexes

Dissociation of amylose – lipid complexes (AMLs) upon gelatinization and enzymatic hydrolysis of wheat starch has been examined using differential scanning calorimetry (DSC). Digestion of starch by the thermostable α‐amylase THERMAMYL 120L was carried out under conditions applied for enzymatic hydrolysis of wheat starch in industry, i.e. 5 min incubation at 105°C, followed by 60–90 min hydrolysis at 95°C. For comparison reasons, samples of wheat starch slurries were incubated under the same conditions but in the absence of enzyme. The enthalpy and temperature of AMLs dissociation and the shapes of peaks in the DSC endo‐ and exotherms depended on conditions of starch processing prior to DSC measurements. Wheat starch gelatinization coupled with its digestion by α‐amylase resulted in more pronounced AML degradation as compared to gelatinization in the absence of enzyme. Different shapes of peaks in thermograms and different temperatures of AMLs dissociation and reassociation indicate that different AML polymorphs were generated in the examined samples. Their concentrations depended on conditions (temperature, time and the presence or absence of α‐amylase) of wheat starch treatment.     

Laboratory‐scale Dry/Wet‐Milling Process for the Extraction of Starch and Gluten from Wheat

A laboratory‐scale process is presented for the manufacture of starch and gluten from wheat. Main feature of this process is that whole wheat kernels are crushed dry between smooth rolls prior to wet disintegration in excess water in such way that gluten formation is prevented and fibres can be removed by sieving. Centrifugation of the endosperm suspension yields a dough which can be separated into starch and gluten using an established batter process. The results suggest that starch recovery is increased in comparison to a conventional wheat flour process without a concomitant decrease in protein recovery. Although starch purification was omitted, a total starch with a low protein content is obtained. On the other hand, the protein content of the gluten fraction is rather low due to difficulties in removing the starch. Despite this, the effect on dough mechanical properties by the addition of gluten obtained from wet‐milled wheat is comparable to the effect of gluten from flour.