酶改性淀粉的添加对纸张物理强度影响的研究

通过添加原淀粉酶转化剂,对玉米原淀粉进行生物改性,测定了改性后玉米淀粉的黏度,探讨了添加该改性淀粉对纸张物理强度的影响,并将其与氧化淀粉的性能作了比较。实验结果表明,淀粉酶制剂能有效地降低原淀粉糊化后的黏度,当原淀粉酶转化剂添加量由0增加至1.0‰时,原淀粉糊化后黏度由11000mPa.s降低至135mPa.s;对于淀粉酶制剂用量为0.5‰,酶改性淀粉用量为2%所抄造的定量为80g/m2纸张,其抗张强度和撕裂度比原样均提高了30%左右,且效果与氧化淀粉作用相当;酶改性淀粉工艺简单易行、使用方便,可降低生产成本,具有较好的实用性和高效性。     

改性淀粉表面施胶剂的稳定性和工业应用经济性评估

本文采用过硫酸铵和α-淀粉酶改性食用玉米淀粉和木薯原淀粉,并将其熬制成胶液用于涂布灰底白板纸的生产中,通过考察各种改性淀粉胶液的黏度和固含量随时间的变化来评估胶液的稳定性,并从原料的成本、设备及工艺方面评估了这些改性淀粉的经济实用性。结果表明:酶改性食用玉米淀粉胶液的稳定性与市售木薯变性淀粉的相当,但胶液中杂质较多;原料便宜,但设备初期投资高,可代替市售木薯变性淀粉用于生产350g/m2以下的涂布灰底白板纸中。     

α-淀粉酶在轻型纸表面施胶中的应用

使用α-淀粉酶制备了高浓度、低黏度的淀粉胶液用作轻型纸表面施胶剂。最佳制备工艺条件:α-淀粉酶加入量0.02%对绝干淀粉)、温度80℃时保温20min、快速升温到98℃保温30min。所得产品固含量9.0%,60℃时黏度5.5～6.5mPa.s。用于60g/m2轻型纸表面施胶时,成纸表面强度提高23.2%,施胶成本吨纸节约33.67元。     

G4酶制取肉制品专用变性淀粉的研究

采用一种新型淀粉酶—G4淀粉酶对非晶颗粒淀粉进行修饰得到肉制品专用变性淀粉,测定了该淀粉的透明度、糊化特性、冻融稳定性和质构特性.并将该淀粉应用到低温火腿肠加工中,对火腿肠进行了嫩度、保水性和质构特性的测定.结果表明:G4淀粉酶修饰后的肉制品专用变性淀粉较原淀粉和化学改性淀粉的糊化温度低,透明度、峰值黏度、冻融稳定性以及热稳定性高,具有显著的抗回生作用,明显地改善了火腿肠品质,提升了出品率,延长了货架期.     

酶转化淀粉在轻型纸表面施胶中的应用

使用α-淀粉酶制备了高浓度、低黏度的淀粉胶液,用作轻型纸表面施胶剂。最佳制备工艺条件为：α-淀粉酶加入量0.02%（对绝干淀粉）;温度80℃时保温20 min;快速升温到98℃,保温30 min。所得产品固含量为9.0%,60℃时黏度5.5～6.5 mPa·s。用于60 g/m2轻型纸表面施胶时,成纸表面强度提高23.2%,施胶成本吨纸节约33.67元。     

木薯羧甲基微孔改性淀粉的制备及性质研究

以木薯淀粉为原料,研究羧甲基微孔改性淀粉的制备及其理化性质.利用糖化酶和α-淀粉酶复合处理制备微孔淀粉,然后采用乙醇溶剂法对微孔淀粉进行羧甲基化处理,确定了制备羧甲基微孔改性淀粉的最佳工艺条件;通过X射线衍射、红外光谱和黏度检测研究木薯羧甲基微孔改性淀粉的理化性质,结果表明羧甲基微孔改性淀粉的结晶度提高,羧甲基基团被引入微孔淀粉分子中;对比原淀粉,羧甲基微孔改性淀粉的黏度明显提高,吸水率和吸油率均高于原淀粉.     

复合酶法油莎豆多孔淀粉的制备及其性质研究

以油莎豆淀粉为原料,通过α-淀粉酶和糖化酶复合制备油莎豆多孔淀粉,并对其结构进行表征。结果表明：油莎豆多孔淀粉的吸油率、吸水率和比容积特性分别提升至167.10%、139.30%、3.40 g/cm3,而抗性淀粉含量有所下降;通过扫描电子显微镜（scanning electron microscope,SEM）观察到多孔淀粉颗粒表面形成少量不均匀孔洞,傅里叶变换红外光谱（Fourier transform infrared spectroscopy,FT-IR）显示没有新峰和化学键的产生;快速黏度分析仪（rapid visco analysis,RVA）显示制备的多孔淀粉黏度较原淀粉降低,峰值时间增大。凝胶质构特性表明,油莎豆多孔淀粉的硬度、内聚性、胶黏性和咀嚼性均优于原淀粉。     

BMT-2酶制备木薯淀粉表面施胶剂的研究

使用国产固体α-淀粉酶BMT-2对木薯淀粉进行改性,考察了温度、pH、底物质量分数、反应时间及α-淀粉酶的加入量等因素对淀粉黏度的影响。研究表明,最佳酶解条件为：温度80℃,pH=6．0,底物质量分数5％,反应时间20min,α-淀粉酶用量为淀粉用量的0．05％。将最佳条件下制得的胶液稀释至质量分数6％,40℃时测得黏度为12．0～14．0mPa·S。将该产品应用于表面施胶,纸张的表面强度有明显提高。     

小麦发芽α-淀粉酶活力及相应条件下淀粉黏度的研究

通过正交试验分析发芽条件(发芽温度,发芽时间,浸泡时间)对小麦发芽过程中α-淀粉酶活力和其淀粉黏度变化.结果表明:在选定的水平下,得到α-淀粉酶活力最高的发芽条件为15℃,发芽6 d,浸泡3 d;g淀粉黏度值最大的发芽条件为20℃,发芽6d,浸泡3 d.α-淀粉酶活力与淀粉黏度随时间变化成反比关系     

蜡质玉米辛烯基琥珀酸淀粉酯理化性质的研究

采用扫描电镜法对蜡质玉米辛烯基琥珀酸淀粉酯的颗粒形貌进行研究,发现蜡质玉米原淀粉颗粒表面比较光滑,经辛烯基琥珀酸酐(OSA)酯化后,淀粉颗粒表面受到一定程度的侵蚀,且受侵蚀的程度随取代度的增加而加深,说明化学反应首先发生在颗粒表面.X-射线衍射实验表明原淀粉的A型晶体结构没有改变,酯化反应发生在淀粉的无定形区,而对内部结晶区没有影响.与蜡质玉米原淀粉相比,酯化反应后淀粉的乳化能力和乳化稳定性均显著增强,能稳定水包油型乳浊液.通过对其糊液的流变性质研究发现,在同一剪切速率下,取代度(DS)越大,其糊的表观黏度越高.并且黏度随剪切速率的升高而降低,糊液呈假塑性流体特征.RVA黏度测试结果表明,随着酯化程度的加深,辛烯基琥珀酸淀粉酯的黏度增加,糊化温度降低,添加10%的蔗糖对其糊液黏度影响不大,氯化钠能抑制其糊化,使其黏度显著降低.     

羟丙基和磷酸酯化对不同玉米杂交种淀粉糊化特性的影响

采用了实验室方法提取了高直链、糯性和普通玉米杂交种的淀粉，并分别进行了羟丙基化和磷酸酯化反应。采用快速粘度分析仪（RVA）和差示扫描量热仪（DSC）分别分析了淀粉的糊化和热力学性质。结果表明：羟丙基化和磷酸酯化反应都不同程度地降低了所有淀粉的热焓值和糊化温度，缩短了出峰时间，增加了峰值粘度。二者相比，羟丙基化更显著地降低了原淀粉的糊化温度和热焓值，缩短了出峰时间；而磷酸酯化则更明显地提高了原淀粉的峰值粘度和终粘度．     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.     

Zur enzymatischen Hydrolyse verschiedener Stärkearten

On the Enzymatic Hydrolysis of Various Starches. The behaviour of different commercial starches to amylolytic enzyme preparations and of their hydrolyzates during raffination was investigated. No significant differences in final degree of saccharification of starches from yellow maize, waxy maize, amylo-maize, potatoes and wheat were observed. The lower De-values of waxy maize hydrolyzates after liquefaction were completely compensated during final saccharification phase. Determinations of viscosity after liquefaction and saccharification always showed highest viscosity in raw hydrolyzates produced from wheat starch. After filtration of the raw hydrolyzates these differences in viscosity were no more observed. Addition of pentosanase during sacharification period did not affect viscosity and filtration of the hydrolyzates. Glucoamylase with increased pentosanase activity affected filtration of wheat starch hydrolyzates positively; viscosity kept unchanged. Development of enzymatic liquefaction of the individual starches was studied by means of a Brabender Viscograph. By this informative differences between potato and waxy maize starches on one side and maize and wheat starches on the other side were observed.     

Rapid Visco-Analyzer (RVA) Pasting Profiles of Wheat,Corn, Waxy Corn,Tapioca and Amaranth Starches (A. hypochondriacus and A cruentus) in the Presence of Konjac Flour,Gellan, Guar,Xanthan and Locust Bean Gums

The Rapid Visco-Analyzer (RVA) 20min test was used to study the effects of different levels of konjac flour, guar, gellan, xanthan and locust bean gums on starch cooking properties. Wheat, corn, waxy corn, tapioca and A. hypochondriacus and A. cruentus starches were affected to different degrees by different levels of the gums. Peak viscosity increased at the higher gum concentrations, especially with locust bean gum at the 0.4 g level. The increase in viscosity was more pronounced with wheat and corn starches than with waxy corn and tapioca starches which consist mostly of highly branched amylopectin thus preventing close physical association between molecules. Amaranth starches showed much lower viscosity with all the gums than the other starches. Peak viscosity, time to reach the peak and maximum setback viscosity were affected by the gums. The increase in viscosity of starch/hydrocolloid systems is due to the release of amy-lose and low molecular weight amylopectin which promotes the formation of polymer complexes and significantly adds to the viscosity of the system.     

Effects of different crop starches on the cooking quality of Chinese dried noodles

To investigate the effects of seven starches made from different crop sources on noodle quality, Chinese dried noodles made from various reconstituted flours were prepared and analysed. Potato starch had better solubility and swelling power than the other starches, leading to higher water absorption, cooking loss and breakage ratio of the potato starch noodles. The correlation results unravelled that the cooking breakage ratio of noodles presented positive correlations with solubility, swelling power, peak viscosity (PV), trough viscosity (TV) and final viscosity (FV) values of starches. Besides, the adhesiveness of noodles showed a positive correlation with conclusion temperature (T_c) and setback viscosity (SV) values of starches. Moreover, the peak temperature (T_p) value of starches was negatively correlated with cooking loss; the granule size of starches had a positive correlation with noodles water absorption; and the peak time (PkT) value of starches represented positive relationships with noodles chewiness, shearing force and breaking strength.     

Effects of protein removal on the physicochemical properties of waxy maize flours

The effects of protein removal on the physicochemical properties of waxy maize flours were investigated. Protein removal caused significant reduction in the P and S contents of starches. Starch granules had a smoother surface and low protein content (<6 g/kg) compared with the flours. Both flours and starches had a typical A‐type X‐ray diffraction pattern, with a crystallinity range of 29.8–32.2% and 27.7–30.6%, respectively. Flours had higher swelling power and solubility, and lower light transmittance than starches. The gelatinization enthalpy and onset temperature of starches were higher compared with those of their counterpart flours. The retrogradation of flours was significantly greater compared with that of starches. Protein removal increased the peak viscosity, trough viscosity, final viscosity, and breakdown, whereas it decreased the setback and pasting temperature. Genotypic differences in those maize were related to the physicochemical characteristics of the flours and starches.     

Physico-chemical Characteristics of Starches from Chick Pea,Cow Pea and Horse Gram

Starches were isolated in 36, 37 and 28% yields, from chick pea, cow pea and horse gram, respectively. Study of their properties revealed mixed granule population; single stage swelling with high solubility in water for cow pea and horse gram starches in comparison to chick pea starch; slightly higher solubility in DMSO for chick pea starch followed by cow pea and horse gram starches; a relatively high viscosity in alkaline solution of cow pea starch; and Brabender amylograms indicating a low slurry viscosity and low set back in the case of chick pea starch compared to the other two starches which exhibited considerable peak viscosity as well as retrogradation. All the starches contained amylose in the range of 32 – 34%. X-ray powder patterns showed chick pea and horse gram starches to be of B-type, whereas cow pea starch was of A-type.     

不同品种小麦淀粉提取及糊化粘度性质比较

采用实验室方法提取30种不同小麦籽粒淀粉;并用快速粘度分析仪(RVA)测定不同品种小麦淀粉糊化粘度性质,分析各粘度性质相关性及差异性。结果表明:普通小麦淀粉糊化粘度性质参数明显不同,粘度性质参数差异性显著,各参数间相关性极显著。     

Effect of beta-cyclodextrin on pasting properties of wheat starch

Changes of viscosity characteristics of genetically diverse hexaploid wheat starches during pasting in water, 1% NaCl solution, or at pH 4 or pH 10 were studied using a Rapid Visco-Analyzer. Peak viscosity (PV), hot paste viscosity (HPV) and cool paste viscosity (CPV) of all the wheat starches was little affected in pH 4 and pH 10 treatments. In 1% NaCl, all starches showed substantial increases in all three parameters relative to pasting in water. The use of 1% beta-cyclodextrin (beta-CD) (cycloheptaamylose) solution increased PV of high-swelling starches, but generally slightly decreased that of low swelling starches in all treatment conditions. HPV was always reduced by addition of 1% beta-CD, but CPV was increased in most treatments for Anza and Yecora Rojo (low swelling), but decreased for Klasic (high swelling). Bacterial alpha-amylase was added to starch or flour. The effect of beta-CD was shown to be independent of alpha-amylase inhibition in wheat starch, but beta-CD strongly inhibited alpha-amylase in wheat flour.     

Comparative Study about Commercially Available Starches for High Shear and High Temperature Applications in Foods

The shear stability and heat resistence of hot starch pastes of more than 30 different commercially available starches has been evaluated. The shear experiments were carried out by a high shear system in the BOHLIN CS rheometer and in comparison outside the rheometer by treatment with a high shear mixer. Native starches are very sensitive against shear stress. The viscosity of non cross-linked chemically modified starches was also decreased. It was not possible to find a correlation between the dependence of shear influence on the viscosity and the type of chemical modification. The high temperature measurements (up to 140°C) in principle showed 3 categories of viscosity development. Firstly, a category, where the viscosity breaks down, secondly, a category where the viscosity remains constant and a last category where the viscosity will be built up during the heating period. No direct dependence on the chemical modification could be observed with respect to the viscosity development.