Starch modification using a twin‐roll mixer as a reactor

A starch modification reactor has been established using a HAAKE rheometer incorporating a twin‐roll mixer, which has been modified to improve its sealing and feeding, and to establish an oxygen‐free environmental. The advantages of the system include: (i) starch modification can be carried out at high starch concentration (up to 70%); (ii) combining the steps of starch gelatinization and chemical modification; (iii) controllable reaction time; and (iv) smaller sample size (60 g) requirement. The effects of water content, rpm, time, and temperature on the reactive system was systematically investigated. Corn starch (60% starch concentration) was successfully grafted with acrylamide then crosslinked by N,N′‐methylene‐bisacrylamide to produce biodegradable superabsorbent polymers using this reactor.     

Granular Properties of Different Starch Phosphate Monoesters

Different starch types (corn, rice, and potato starch, corn amylose and corn amylopectin) were phosphorylated by reaction with a mixture of mono and disodium phosphate at different molar ratios (mol phosphate/mol anhydrous glucose) under heat and vacuum. The starch granules of the modified and the native starches were microscopically examined for their sizes and morphology. The correlation between the variation in granular size of the modified starches with the extent of phosphorylation and some other physicochemical properties was studied. The granular size was generally increased while the iodine absorption capacity was decreased by phosphorylation. There were strong correlations between the variation in the starch granular size in dependence on phosphorylation and the corresponding changes in some physicochemical parameter of starch, e.g. solubility, swelling and paste clarity. This relationship was most evident in the case of phosphorylated corn amylopectin. Starch granular size can be taken as a quick indicator of the physicochemical properties of the native and modified starches.     

水分散性聚酯与淀粉混合浆液性能研究

研究了水分散性聚酯浆料与淀粉浆料浆液、浆膜的性能，结果表明，水分散性聚酯浆料与淀粉有很好的混溶性，能提高淀粉浆液的粘度热稳定性，显著改善与涤棉混纺纱的粘附性能；加入水分散性聚酯对淀粉浆有较好的增塑作用，能改善淀粉浆膜的物理机械性能和退浆性能；用于经纱上浆能部分取代PVA。     

Characteristics of Different Types of Starch in Starch Noodles and Their Effect on Eating Quality

Several commercial starch noodles made from legume, tuber, geshu (kudzu and sweet potato) and fernery starches were used to study the characteristics of starch in starch noodles and their effect on eating quality of starch noodles. Scanning electron microscopy observation found that the special inner structure of starch noodles was composed of some broken starch granules and some gel-like substances. Tuber and legume starches had the highest and lowest solubility, swelling power, swelling factor, setback, breakdown, peak viscosity, and final viscosity, respectively. Legume and tuber starches had the highest and lowest gelatinization temperature, respectively. Tuber and geshu starches had the highest amylose leaching rate, while legume starches owned the lowest value (p < 0.05). Tuber starches had the highest conclusion temperature of gelatinization (151.12~158.86°C). Fernery starches had the lowest value of retrogradation enthalpy (967.33 J/g dry starch). Legume starch noodles had the lowest broken rate (0.00~1.67%), swelling ratio (332.64~343.57%), and cooking loss (2.40~2.74%), and the highest hardness (87.47~93.29 g/mm2), shear deformation (0.49~0.52), and elasticity (0.58~0.62), However, tuber and fernery starch noodles did the opposite, tuber and legume starch noodles had the highest and lowest cohesiveness, respectively. All the above cooking and starch properties test results of starch noodles demonstrated that, compared with others, legume starch noodles are relatively well in eating quality. The correlation analysis showed that the cooking and physical quality of starch noodles could be perfected significantly by improving the swelling and pasting properties for starch of starch noodles, while thermal properties had no obvious influence on them.     

拟均相两段工艺氧化法制备双醛淀粉

以绿豆淀粉为原料,NaIO4为氧化剂的拟均相两段工艺制备双醛淀粉(dialdehyde starch,DAS),考察预处理阶段中温度、酶处理、超声活化和氧化阶段中反应温度、反应时间、pH值、投料比、NaIO4浓度、淀粉乳浓度、相转移催化剂对制备双醛淀粉的影响,前段的预处理采用超声活化处理,后段的氧化工艺考察相转移催化剂的影响,并用正交法对制备双醛淀粉的工艺进行优化。结果表明：在以醛基含量为考察指标,预处理时不宜用酶,处理温度50～60℃,经30℃、40W、40kHz超声活化淀粉乳30min能有效提高淀粉与NaIO4的氧化反应活性,制得高醛基含量的DAS。相转移催化剂对提高产品醛基含量有一定作用。经正交试验优化得到的最佳条件为：以十六烷基三甲基氯化铵为相转移催化剂、反应时间2h、反应温度40℃、n(NaIO4):n(淀粉)=1.0:1.0、NaIO4浓度0.5mol/L、淀粉乳质量分数10%、体系pH2,在此条件下,制得的DAS双醛含量为96.81%。经光谱和理化性能等指标的检测证实所得的DAS与文献报道的DAS相符合。     

烘烤过程中不同成熟度烟叶淀粉的降解动态

以烤烟品种红花大金元和K326的中部叶为材料,研究了不同成熟度烟叶烘烤过程中淀粉酶和淀粉磷酸化酶活性动态及对烤烟淀粉降解的影响。结果表明:淀粉的降解是淀粉酶和淀粉磷酸化酶综合作用的结果。烘烤过程中烟叶淀粉酶活性出现两次高峰,分别在烘烤的36h和72h;在鲜烟叶中淀粉磷酸化酶活性较高,随着烘烤过程的推进,至24h时达第1次高峰,之后降低,48h时出现低谷,随后又于72h达第2次高峰。不同成熟度的烟叶中淀粉酶和淀粉磷酸化酶活性相比较,均以适熟叶中两种酶的活性较高,淀粉降解较快,烤后烟叶淀粉含量较低,水溶性糖和还原糖含量较高,总体化学成分较协调。     

Preparation of highly substituted carboxymethyl starch using a twin‐screw extruder

Carboxymethyl starch was prepared by reacting corn starch with sodium mono chloro acetate (SMCA) in a Brabender TSE‐20 co‐rotating twin screw extruder. The effects of the SMCA/starch ratio (theoretical degrees of substitutions 2.73, 3.62, and 4.53), aqueous ethanol/(starch + SMCA) ratio (0.13 and 0.25) and the screw configuration (0, 1, and 2 kneading blocks) on the degree of substitution (DS) and reaction efficiency were studied. A 3 × 2 factorial design with 3 levels of the starch/SMCA ratio and 2 levels of the aqueous ethanol/(starch + SMCA) ratio were used. This 3 × 2 factorial design was blocked, with the screw configuration as the blocking variable. The effects of the SMCA/starch ratio and the screw configuration were found to be significant. The carboxymethylated starches were characterized using FTIR, SEM, and XRD. The microstructure of the carboxymethylated starches, studied using SEM, revealed that the integrity of the starch granules was partially preserved at low aqueous ethanol levels when no kneading block was used. However, for all other reaction conditions either granule agglomeration or fusion was observed. XRD analysis indicated substantial loss of crystallinity in the carboxymethylated starches, irrespective of the damage to the granule structure. The highest DS and the highest reaction efficiency obtained were 1.54 and 0.42, respectively.     

十二烯基琥珀酸淀粉酯的制备研究

本文研究以小麦淀粉和十二烯基琥珀酸酐为原料制备酯化淀粉,探讨了反应时间、反应温度和微波对产品取代度的影响并得到最佳工艺条件:预处理淀粉经微波幅射 30 秒后 35℃水浴反应 7 小时,可制得取代度为 0.022 的产品。     

Synthesis and Optimization of the Reaction Conditions of Starch Sulfates in Aqueous Solution

Starch sulfate was prepared by chemical modification of potato starch with trisulfonated sodium amine (N(SO₃Na)₃), which was synthesized by reaction of sodium bisulfite and sodium nitrite in aqueous solution. The factors that could affect the degree of substitution (DS) of potato starch were investigated in detail, which included reaction temperature and time of preparing the sulfating agent, reaction temperature and time of synthesizing the starch sulfate, dosage of sulfating agent and potato starch, pH of sulfation reaction medium, and the ratio of liquid volume to starch mass. A starch sulfate with DS of 2.14 was obtained under optimal conditions. FTIR spectra showed the characteristic absorptions of sulfate ester bonds at 1236 cm⁻¹ and 821 cm⁻¹.     

Effect of Reaction Conditions and Alkyl Chain Lengths on the Properties of Hydroxyalkyl Starch Ethers

Starch applications in the plastics industry have been investigated intensively for many years. Unfortunately, native starch is unsuitable for most applications in polymers, because of its hydrophilic and brittle character. Modification of native starch can be a solution of this problem. In our research programme we developed an environmentally friendly process for the preparation of starch derivatives with long hydrophobic side chains based on natural products derived from vegetable fats and oils on the one hand and amylomaize starch on the other hand. In this process modification is carried out by the addition of longchain 1,2‐epoxyalkanes (chain lengths varying between 6—18 C atoms) to starch in an alkaline aqueous medium. Reaction yields and molar degrees of substitution depended on chain length, reaction time, temperature and catalyst concentration. Under optimised reaction conditions molar degrees of substitution of hydroxyalkyl starch ethers for theoretical molar substitution (MS) = 3.0 decreased from MS=1.8 (C₆ starch ether) to MS=0.2 (C₁₈ starch ether), respectively. Hydrophobic properties of starch products were measured in order to reveal structural effects obtained at different reaction conditions. Water solubility and water absorption properties of hydroxyalkyl starch ethers decreased with increasing chain length and number of hydroxyalkyl substituents. Thermal and thermoplastic properties of starch ethers were investigated in order to determine their potential use as biodegradable polymers in the plastics industry. As expected, thermoplasticity of starch ethers increased with increasing MS and increasing chain length of the hydroxyalkyl side groups.     

纳米SiO2对不同淀粉品种的适用性分析

为研究纳米S iO2助剂对淀粉品种的适用性。选择木薯淀粉、玉米淀粉、小麦淀粉及马铃薯淀粉4种淀粉,采用小型浆纱机对纯棉经纱进行了上浆试验。试验结果表明,在淀粉浆料中添加适量纳米S iO2助剂之后,对提高淀粉的浆纱性能具有显著效果,各淀粉品种对浆纱耐磨性和毛羽降低率的影响按照小麦淀粉、木薯淀粉、玉米淀粉、马铃薯淀粉的顺序逐渐提高。     

Starch Structure and Digestibility of Rice High in Resistant Starch

Starch digestibility and starch structure of a high‐resistant starch (RS) rice (RS111) was compared to that of a wild rice type (R7954). RS111 exhibited high RS content and incomplete starch hydrolysis in both cooked rice and retrograded rice flour. High RS rice RS111 had a higher λ_max of absorbance and blue value of iodine‐binding starch complex and contained a higher percentage of intermediate chains of amylopectin than R/954. X‐ray diffraction pattern of RS isolated from cooked high RS rice displayed a mixture of B‐ and V‐type that was more resistant to starch hydrolysis by alpha‐amylase. Resistant starch in RS111 is composed mainly of linear amylose and some low‐molecular‐weight amylopectin.     

高抗性淀粉稻米魔芋果冻糖的加工工艺研究

以高抗性淀粉稻米和魔芋精粉为主要原料研制出一种新型营养果冻型软糖.通过实验,果冻糖以高抗性淀粉稻米3%,魔芋精粉0.8%,木糖醇20%,柠檬酸0.25%的配比最好,煮胶温度控制在65℃最适宜.     

颗粒α-化修饰淀粉制备工艺条件的优化

采用乙醇-碱溶液处理淀粉的方法,在常压状态下对淀粉进行α-化修饰,以溶解度和黏度作为评价指标,通过正交试验和响应面分析,得出制备颗粒α-化修饰淀粉的最佳工艺条件:反应温度53.90℃,碱用量4.50 g,乙醇体积分数44.08%,乙醇用量829.19 g。     

挤压法制备大米抗性淀粉中系统参数控制与目标参数的关系

采用正交试验,进行挤压法制备大米抗性淀粉的研究,得到了挤压法制备大米抗性淀粉的最佳工艺条件:大米粉水分含量40%,挤压机腔体170℃,螺杆挤压频率35Hz,储藏时间7d,储藏温度4℃,喂料机喂料频率20Hz。在此工艺下,抗性淀粉得率8.77%,与原料相比,抗性淀粉含量提高了近7倍。在正交试验的基础上,建立了反映挤压法制备大米抗性淀粉中系统参数控制与目标参数关系的回归方程:Yi=-4.1408 0.1655XA 0.0402XB 0.0069XC-0.0299XD 0.0586XE 0.0911XF     

水相高温处理对淀粉结构与性质的影响

淀粉作为食品中的主要成分之一,在人类饮食中起着重要作用。蒸制、水煮、挤压作为淀粉基食品加工中常用的3种水相高温处理手段,对淀粉的颗粒形态、分子结构、晶型、糊化、老化和消化等都会产生重要影响。作者综述了蒸制、水煮、挤压处理对淀粉结构与性质的影响,以期为提升淀粉类食品品质提供理论依据。     

Effect of Processing on Slowly Digestible Starch and Resistant Starch in Potato

The effect of a number of laboratory‐scale pretreatments on the proportions of rapidly digested (RDS), slowly digested (SDS) and resistant starch (RS) in raw and cooked potato has been examined using an in vitro digestion procedure. Potatoes of the variety Frisia were prepared in three states: raw, cooked, and cooked followed by a cold treatment (4°C, two days). Each preparation was then subjected in triplicate to freeze‐drying, coarsely mincing, pasting, freezing, dry‐milling after freeze‐drying, in 22 different combinations, before digesting. In raw potato, very little RDS and SDS (<5% total starch (TS)) were present, and the mechanical treatments of the potato did not affect the amounts of RDS and SDS. Cooking resulted in an almost complete conversion to RDS (>95% TS) in freshly‐cooked potato, but after post‐cooking cold treatment much of the RDS transformed to SDS, which reached a maximum of about 45% TS. SDS formation was independent of the degree of tissue disruption after cooking, and was generally associated with formation of RS, however, freezing after cooking allowed SDS formation without prolonged cold treatment and with very little associated RS (SDS 35% and RS 4% of TS). Freeze‐drying caused an increase in RS in most treatments of the cooked potatoes. The observed effects provided guidance for sample handling in potato research, but also suggested several approaches to the enrichment of SDS and/or RS, with a concurrent reduction in RDS, that could be used to improve the nutritional profile of potato products by decreasing RDS (lowered glycaemic impact), and increasing SDS (more sustained energy availability) and RS (prebiotic benefits).     

High‐resolution Imaging of Starch Granule Structure using Atomic Force Microscopy

Atomic force microscopy (AFM) was carried out for the precise structural analysis of starch granules. AFM is a useful technique to obtain — under atmospheric conditions — high‐resolution images which are as good as those obtained by conventional scanning and transmission electron microscopy. The samples for observation by AFM do not require complicated preparations such as the drying and metal coating as in the case of electron microscopy. The AFM technique is suitable for the precise structural observation of bio‐materials in which damage caused by drying and heating must be avoided and the effect of the thickness of the metal coating must be considered. Several preparation methods for exposing the bare inner surface of starch granules were studied in the beginning. AFM structural analyses on the nanometer scale were carried out on starch granules from five different botanical sources which were prepared by a physical method. It was directly demonstrated that fine particles of approximately 30 nm in diameter existed inside each granule and occasionally formed a straight chain structure. These fine particles may correspond to the individual blocklet or single cluster which has been proposed in the starch structural model previously discussed.     

Viscosity,Swelling and Starch Leaching During the Early Stages of Pasting of Normal and Waxy Rice Starch Suspensions Containing Different Milk Protein Ingredients

The effects of three milk protein ingredients, sodium caseinate (NaCAS), whey protein isolate (WPI) and skim milk powder (SMP), on the swelling and leaching behaviour of normal and waxy rice starch solutions, during the early stages of pasting, were investigated. It was found that the swelling onset temperature for both starches was increased by NaCAS and SMP but was not affected by WPI. Furthermore, onset temperature determined by the swelling measurements was lower than the onset temperature determined from viscosity measurements. However, the calculated viscometric onset temperature, using the Maron‐Pierce equation and the results of the swelling measurements, was found to be in very good agreement with the measured viscometric onset temperature. This study also showed that the quantity of leached polysaccharides during the early stages of starch pasting was very small, indicating that significant leaching of polysaccharides during pasting primarily occurs after the break‐up of the sheared starch granules.     

山黧豆蛋白质分离同步制备淀粉的工艺条件优化

为探索山黧豆淀粉提取工艺条件,采用浸泡法与碱性蛋白酶酶解蛋白相结合的方法确定了提取山黧豆蛋白质同步制备淀粉的适宜工艺条件。结果表明：山黧豆浸泡法分离提取蛋白质的影响因素依次为浸泡料水比、pH值、浸泡温度,适宜的浸泡条件为浸泡料水比1：10、pH值10．5、温度55℃,蛋白质提取率可达64．88％;碱性蛋白酶酶解浸泡后山黧豆残粕中的残留蛋白,影响酶解效果的因素依次为酶用量、温度、时间、pH值,在碱性蛋白酶400U／g、60℃、120min、pH值10．5时酶解效果较好,最终淀粉成品中的蛋白质残留量低于0．70％。