Effect of acetylation on the properties of corn starch

Acetylated corn starches with different degrees of substitution (DS 0.85, DS 1.78, DS 2.89) were synthesized by the reaction of corn starch with acetic anhydride in the presence of acetic acid under varying reaction temperatures. The product was characterized by FTIR spectroscopy, ¹H NMR, X-ray diffraction and contact angle measurement. Acid-base titration and ¹H NMR methods were employed to determine the degree of substitution of product. FTIR spectroscopic analysis showed that the characteristic absorption intensities of esterified starch increased with increase in the degree of substitution, and the characterized peak of hydroxyl group almost disappeared in the spectrum of DS 2.89 acetylated starch. The detailed chemical microstructure of native starch and acetylated starch was confirmed by ¹H NMR, ¹³C NMR and ¹³C–¹H COSY spectra. Analysis of ¹H NMR spectra of acetylated starches was assigned accurately. Strong peaks in X-ray diffraction of acetylated starch revealed that new crystalline regions were formed. Compared with native starch, the hydrophobic performance of acetylated starch esters was increased. The contact angle of acetylated starch with DS 2.89 was 68.2°.     

玉米淀粉的机械活化及其流变特性研究

通过搅拌球磨机对玉米淀粉进行机械活化降解，并利用X-射线衍射仪（XRD）和旋转粘度计对玉米淀粉的降解程度及流变学特性进行了研究。结果表明：机械活化使得淀粉颗粒结晶结构受到破坏，结晶程度降低。最终由多晶态转变成非晶态。同时所有的机械活化淀粉均呈现假塑性流体特征，符合幂定律，机械活化使玉米淀粉偏近牛顿流体，且活化时间越长、活化温度越高的样品，其糊的表观粘度越低，触变性和剪切稀化也越低。     

机械活化预处理对木薯淀粉氧化产物理化性质的影响

研究机械活化预处理对木薯淀粉氧化产物理化性质的影响。采用搅拌球磨机对木薯淀粉进行机械活化,以不同活化时间的木薯淀粉为原料,CuSO4为催化剂,H2O2为氧化剂干法制备氧化淀粉,对由不同活化时间木薯淀粉制备的氧化淀粉的溶解度、表观黏度、透明度、冻融稳定性、凝沉性等性质进行研究。试验结果表明：机械活化预处理对木薯淀粉氧化产物的理化性质产生显著的影响,随着机械活化时间的延长,氧化淀粉的溶解度、透明度增大,表观黏度降低,冻融稳定性减弱,凝沉性增强。     

Effect of corn starch on the structure,physicochemical and gel properties of hairtail (Trichiurus haumela) myosin

Effects of corn starch on structure, physicochemical and gel properties of myosin were investigated. Particle size, turbidity, surface hydrophobicity and total sulphhydryl groups of myosin were significantly increased with the increasing of starch concentration, and the increase range of high amylose corn starch (HACS) group was the most significant. Tryptophan residue of myosin was buried, and fluorescence quenching occurred after starch was added. HACS made myosin secondary structure was changed from α-helix to β-sheet. Confocal laser scanning microscopy (CLSM) photographs showed starch was encapsulated by aggregated myosin, which made the protein binding tighter and more beneficial to the formation of gel. Moreover, strength and water holding capacity of heat-induced myosin gels containing starch were significantly higher than that of pure myosin. Starch, especially HACS, could induce myosin aggregation before heating gelatinisation and promote myosin self-assembly at low temperature, which may be conducive to forming a higher quality gel after heating.     

玉米淀粉/卡拉胶/甘油复合膜的最佳成膜工艺研究

目的 确定玉米淀粉/卡拉胶/甘油复合膜的最佳成膜工艺.方法 以玉米淀粉为基材,与卡拉胶和甘油共混,通过流延法制备复合膜,以薄膜的机械性能为评价指标,通过单因素实验及正交实验来确定最佳成膜工艺.结果 正交实验结果表明当玉米淀粉添加量为3％、卡拉胶添加量为30％、甘油添加量为25％时,玉米淀粉薄膜的机械性能最佳.结论 本研...     

Thermal,rheological, and mechanical properties of normal corn and potato starch blends

Native corn and potato starches were mixed in different proportions. Blends presented similar values to potato starch at onset temperature and at ending temperature to corn starch. CS20PS80 blend had the highest values for hardness between blends due to the formation of a three-dimensional network with corn starch granules that act as composite material. Some blends exhibited higher recovery viscosity than native starches, possibly due to interactions. Gelatinization temperature, swelling power, phosphorous content, granule size, and x-ray pattern played an important role in the resulting properties, however, the amylose content did not show influence due to both starches having a similar content.     

机械活化处理对绿豆淀粉理化性质的影响

为探究球磨机械活化处理对绿豆淀粉理化性质的影响,对机械活化后绿豆淀粉的颗粒形貌和粒度分布进行观察,并进一步对其热力学性质、糊化性质、溶解度、膨胀度、持水能力和冻融稳定性等理化性质进行测定。结果表明,淀粉颗粒形貌发生了改变,表面变得粗糙不光滑,形状不规则,淀粉颗粒粒度分布范围为2～200 μm,70%以上分布在20～75 μm区间,粒度中位径增大到43.09 μm,热焓值降低至2.32 J/g,糊化温度显著降低,衰减值及回生值分别为原淀粉的1/30和1/31,微细化绿豆淀粉具有较好的热糊和冷糊稳定性,溶解度和膨胀度随着温度的升高而增大,持水能力和冻融稳定性为原淀粉的3.2倍和2.0倍。     

酸奶对玉米淀粉流变特性的影响

乳酸菌发酵能够产生淀粉酶。为考察含有活性乳酸菌的酸奶对淀粉黏弾特性的影响,本文以玉米淀粉为原料,分别加入1%（v/v）的蒙牛酸奶、完达山酸奶、伊利酸奶,并在37℃保温1小时;用流变仪研究发酵后玉米淀粉的流变学性质。实验结果表明：剪切流变曲线服从Herschel-Bulkley模型 （R>0.90）。屈服应力τ0、粘度系数k增加,流动指数n减小（n<1）,显示发酵后的玉米淀粉仍然是非牛顿、屈服假塑性流体。震荡流变曲线显示添加酸奶的样品组的贮能模量G''与损耗模量G''均大于空白组、且均随着剪切频率的增大而增大。本项研究首次发现经乳酸菌发酵的玉米淀粉,具有更高的黏弹特性。     

Effects of cross-linking and acetylation on oat starch properties

Starch samples separated from oat were modified with two different levels of POCl₃ (0.5 and 1.0 g kg⁻¹) as a cross-linking agent and two different levels of acetic anhydride (6% and 8% (w/w)) for acetylation. Swelling factor, thermal properties and retrogradation measurements were evaluated to characterise the influence of phosphorylation and acetylation on oat starch. Cross-linking decreased the swelling factor and did not improve gelatinization temperature while it increased synaeresis in comparison with native starch. Acetylation increased swelling factor but reduced gelatinization temperature and synaeresis of oat starch.     

Influence of hydroxypropylsulfonation on adhesion-to-fibers and film properties of corn starch

Abstract

The objective of this work was to investigate the influence of hydroxypropylsulfonation on the adhesion-to-fibers and film properties of starch for improving its end-use ability in warp sizing. A series of hydroxypropylsulfonated corn starch (HPSS) with different degrees of substitution (DS) were synthesized by the reaction of granular corn starch with 3-chloro-2-hydroxy-1-propanesulfonic acid sodium salt (CHPS-Na) in an alkaline aqueous medium. The adhesion was accessed by determining the tensile force of starch to cotton fibers according to a standard method (FZ/T 15001-2008), while film properties were estimated in terms of breaking elongation, tensile strength, degree of crystallinity, and moisture regain. In addition, desizability of HPSS was also evaluated by measuring the time interval required to break the film in water. The estimation was undertaken through the comparison of HPSS with ACS. Compared with ACS, HPSS exhibited stronger tensile force, higher breaking elongation and moisture regain of the film, and lower tensile strength, degree of crystallinity and time required to break the film in water. Therefore, hydroxypropylsulfonation was able to improve the adhesion, reduce film brittleness, and enhance the desizability. The increase in the hydroxypropylsulfonation level favored the increase in adhesion, reduction of film brittleness, and enhancement in desizability. Based on the results, HPSS prepared with a DS range of 0.03?～?0.041 showed the potential for the application of sizing cotton warp yarns.     

不同玉米品种理化特性及淀粉品质的研究

从河北省玉米主栽品种中选取15个玉米品种作为供试材料,对玉米粉的白度、色差、蛋白质含量、脂肪含量、淀粉含量及玉米淀粉透明度、持水率、溶解度与膨胀势、冻融稳定性、凝沉性、糊化特性、凝胶质构以及微观结构进行系统研究。结果表明,不同玉米品种理化性质及淀粉品质间差异显著,并对淀粉品质测定结果进行分析,将所选的15种玉米根据类别分为糯玉米和普通玉米两大类,然后对普通玉米品种进行聚类分析,在平方Euclidean距离为10处,可将14种普通玉米根据淀粉性质分为3类,因此可根据不同加工目的选择不同类型的玉米品种。     

羟丙基玉米淀粉的制备及特性研究

本文研究了用环氧丙烷制备羟丙基玉米淀粉的反应条件以及羟丙基化对玉米淀粉糊特性的影响,在反应条件中,着重研究了淀粉乳浓度、环氧丙烷用量、反应温度和时间对醚化程度以及反应效率的影响规律,试验表明：羟丙基化能大大提高玉米淀粉糊的抗剪切性能和抗盐性能,使淀粉糊的透明度和冻融稳定性都有所增加。     

机械活化对玉米氧化淀粉糊性质的影响

采用搅拌球磨机对玉米淀粉进行机械活化,以不同活化时间的玉米淀粉为原料,CuSO4为催化剂,H2O2为氧化剂干法制备氧化淀粉。对不同活化时间玉米淀粉氧化产物的溶解度、糊的表观黏度、透明度、冻融稳定性、凝沉性等性质进行研究。结果表明,机械活化预处理对玉米淀粉氧化产物糊的性质产生显著的影响。随着机械活化时间的延长,氧化淀粉的溶解度、透明度增大,表观黏度降低,冻融稳定性减弱,凝沉性增强。     

Physical properties and chemical forces of extruded corn starch fortified with soy protein isolate

The effect of soy protein addition on physical properties of extruded corn starch was studied. The correlations between the chemical bonds in proteins and the physical properties of extrudates were analysed. Increasing soy protein isolate content resulted in higher expansion ratio (ER) but lower bulk density (BD), hardness, water solubility index (WSI), degree of starch gelatinisation (DSG), content of sulphydryl (SH) groups and protein solubility in phosphate buffer. In the other hand, increasing the processing temperature resulted in higher ER, water absorption index, DSG, contents of the SH group and disulphide (SS) bond but in lower specific mechanical energy, BD, hardness and WSI. The results indicated that changes in the chemical bonds in proteins had a significant effect on the apparent physical properties of extrudates. More protein–protein and protein–starch cross‐linking reactions occurred through new chemical linkages, such as the nondisulphide covalent bonds and hydrogen bonds, which are beneficial to the expansion of starch‐based products.