Facile preparation of sago starch esters using full factorial design of experiment

A facile solvent‐free method to acetylate sago starch (Metroxylon sagu) is reported. Microwave (100 W) was used as the heating source and the heating time was varied from 2 to 10 min with the temperature of acetylation maintained at 100°C under continuous stirring. Using a 2⁴ full factorial design of experiment, it was found that the degree of substitution (DS) of acetylated sago starch was strongly affected by the ratio of starch to acylating reagents, the ratio of acetic anhydride to acetic acid as the acylating reagents, the concentration of iodine as catalyst and reaction time. The physicochemical characteristics of the acetylated sago starch were assessed based on the FTIR spectra, the XRD spectra, the water absorption index (WAI), and the water solubility index (WSI). SEM was used to study the surface morphology of the acetylated sago starch at different DS.     

超高压辅助制备醋酸酯淀粉结构性质研究

以玉米淀粉为原料,乙酸酐为反应试剂,NaCl为反应介质,采用超高压辅助制备醋酸酯淀粉,利用光学显微、X-射线衍射、快速黏度分析技术对醋酸酯淀粉结构性质进行分析。研究表明,颗粒态醋酸酯淀粉结晶类型与原淀粉相同,当处理压力为600 MPa时淀粉糊化,颗粒结构被破坏,A型结晶向V型结晶转换,但糊化并不利于醋酸酯淀粉取代度的增加。适量NaCl的添加有利于超高压处理时淀粉颗粒态的维持,因而有效提高了醋酸酯淀粉的取代度。当NaCl溶液浓度为1.0%、乙酸酐添加量为2.0%、压力为400MPa时,所制备的醋酸酯淀粉取代度达到最大值(0.090),且表现出较高的峰值黏度(400.00cP)。     

Effect of Storage on Starch Content and Modification of Cassava Starch

The effect of storage on yield and modification of starch using hydrochloric acid and acetic anhydride were studied. Yield of starch from fresh roots (24.4%) was significantly greater than yield (16,2%) from roots stored at room temperature for six days. On a dry weight basis the amount of starch in the roots decreased over a six day storage period. The proximate composition of cassava starch on dry weight basis was 0.24% ash, 0.13% fat, 0.49% protein, 0.15% crude fibre and 98.4% starch. The isolated starch was treated with different concentration of hydrochloric acid to produce acid thinned and dextrinized starches and different concentration of acetic anhydride to produce acetyl substituted starches. The alkali number of acid thinned and dextrinized starches increased with acid treatment while the viscosity decreased. The degree of substitution increased with the concentration of acetic anhydride used. The cold water solubility of the acid thinned and acetyl substituted starches were similar to that of native starches while the solubility of the dextrinized starches increased with the acid concentration. The viscosity of the acetyl substituted starches increased with the degree of substitution.     

乙酰化酸解复合变性淀粉的制备及性能研究

本文以玉米淀粉为原料,以盐酸为酸解剂,醋酸酐为乙酰化试剂,氢氧化钠为酰化催化剂对酸解乙酰基复合变性淀粉合成工艺进行了研究。考察了反应时间、反应温度、pH值、酸含量对酸解淀粉流度、乙酰化淀粉取代度及产品性能的影响。实验结果表明,升高酸解温度、增加酸解时间和酸含量将加速淀粉的降解。采用流度法测定酸解淀粉的粘度,采用酸碱滴定法测定了乙酰化酸解淀粉的取代度。     

Effect of the production method on the properties of RS3/RS4 type resistant starch. Part 2. Effect of a degree of substitution on the selected properties of acetylated retrograded starch

Resistant starch displays health-promoting properties. Starch preparations produced through acetylation of retrograded starch may be applied as a food additive. Apart from prebiotic properties, they may as well model the texture of a food product. The objective of this study was to determine the effect of retrogradation and acetylation conditions on properties of the produced RS3/4 type resistant starch. Native potato starch was used to produce starch pastes (1, 4, 10, 18 or 30g/100g), that were frozen, defrosted and dried. The resultant preparations of retrograded starch were acetylated with various doses of an acetic acid anhydride (3.25, 6.5, 13.0, 26.0 or 52.0ml/100g). The acetylated preparations of retrograded starch were characterised by increasing solubility in water and swelling power as well as a lower amylose content along with an increasing degree of their substitution with residues of acetic acid. Dependencies of: pasting temperatures, viscosity of the prepared pastes, and resistance of acetylated starch to the action of amyloglucosidase on the degree of substitution with acetic acid residues were described with a second degree polynomial function. The extent and range of changes were found to depend on the concentration of paste used to produce a retrograded starch preparation. The maximum resistance of RS3/4 preparations to the action of amyloglucosidase ranged from 28.7 to 45.9g/100g.     

低取代度乙酰化绿豆淀粉的性质

以绿豆淀粉为原料,冰醋酸为乙酰化剂,制备低取代度的乙酰化绿豆淀粉。对乙酰化绿豆淀粉的膨润力、溶解度、凝沉性、透明度、黏性、质构特性等进行研究。结果表明：与原淀粉相比,经过乙酰化处理的绿豆淀粉透明度、膨润力、溶解度均比原淀粉有所增加,糊化温度降低,谷值黏度、末值黏度有所升高,而峰值黏度、衰减值则降低,绿豆淀粉乙酰化后凝胶特性也有所改善。     

Influence of acetylation on physicochemical, functional and thermal properties of potato and cassava starches

Starches were isolated from cassava (Manihot esculenta) and potato (Solanum tuberosum) tubers. They were further modified by acetylation. The physicochemical, functional and thermal properties of native and modified starches, prepared using acetic anhydride at different times (10 and 20 min) were compared. Potato starch (Sipiera/20) showed higher acetyl percentage and degree of substitution values than cassava (2425/20) starch when acetylated for 20 min. Proximate analysis revealed that the acetylated starches retained more moisture than the native ones. Above 75 °C, acetylation improved the water binding capacity of the native cassava starch; the same trend was observed for potato starch from 60 to 90 °C after acetylation. The X-ray powder diffraction patterns derived from acetylated potato starches were similar to its native form, which was expected as B-type pattern; the same trend was observed for modified cassava starch. However the modified starches showed increased crystalline index.     

原料和制备方法对醋酸酯淀粉糊化特性的影响

以三种淀粉(马铃薯、木薯和玉米淀粉)为原料,以醋酸酐、醋酸乙烯酯为酯化剂生产醋酸酯化淀粉,对其Brabendar粘度曲线图进行研究。经酯化后,淀粉的糊化特性都有明显的变化(起糊温度降低,粘度增加),但原料和酯化剂的不同,会导致变化程度的不同,另外冷热糊稳定性和凝胶性强弱变化就有更明显的差异。     

Functional and dynamic rheological properties of acetylated starches from two cultivars of cassava

The starches derived from two different cultivars of cassava were modified with acetic anhydride. The increase in swelling power and solubility of the cassava starch (CS) pastes treated with different acetic anhydride concentration could be attributed to easier hydration, resulting from reduction of interaction between starch chains due to the substitution. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinisation (ΔH) of acetylated CS, were determined. The values were lower than those of native starches. Rheological properties of CS pastes (5% w/w) as a function of the degree of substitution were evaluated in dynamic shear force measurements. Magnitude of storage modulus (G′), loss modulus (G′′) and complex viscosity (Eta*) of acetylated CS pastes were determined also. Dynamic moduli (G′, G′′ and Eta*) values of acetylated sweet cultivar pastes were generally higher than those of native starch whereas the acetylated samples of the bitter cultivar were lower than those of native starch. The magnitudes of G′ were greater than those of G′′ and Eta* at all frequencies (ω). The fact that all the tan δ (ratio G′′/G′) values (0.7–0.48 and 0.25–0.44) were less than one is an indication that the samples are more elastic than viscous. The acetylated starches could find promising industrial uses in food products like Lemon curd and Mayonnaise and other non‐food applications.     

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°.     

Lysine in cassava based diets: II. The nutritional evaluation of acetylated casein in maize meal,corn starch and cassava based diets

Casein was acetylated with sodium acetate/acetic anhydride and was found to be 98·5% acetylated by the FDNB available lysine method.The PER of maize meal and corn starch diets decreased with increasing amounts of acetylated casein. The PER of a maize meal—casein diet was 2·21 but this decreased to 2·13 and 1·60 when acetylated casein was incorporated at 5 and 10% levels, respectively. The same trend was observed for corn starch diets with a PER of 1·60 for a casein—corn starch diet but PERs of 1·28 and 0·91 when acetylated casein was added at 8 and 16% levels, respectively.In the presence of cassava, the nutritional value of acetylated casein was enhanced. Thus a meal made of 10% acetylated casein: 50% cassava: 25% maize meal had a PER of 2·06 compared to 1·60 for a diet consisting of 10% acetylated casein: 70% maize meal. At 16% acetylated casein: 70% cassava the PER was 1·75 compared to 0·91 in a 16% acetylated casein: 70% corn starch diet.A similar trend was observed for NPU, NPR and serum urea levels for the respective diets considered.Acetylated casein moderately elevated the activity of urine enzymes (LDH, GDH, alkaline and acid phosphatases) in corn starch based diets while cassava based diets appeared to depress the level of the enzymes.     

Study on the morphology,crystalline structure,and thermal properties of Fritillaria ussuriensis Maxim. starch acetates with different degrees of substitution

Fritillaria ussuriensis Maxim. starch acetates with different degrees of substitution (DSs) were prepared by reacting native starch with glacial acetic acid/acetic anhydride using sulfuric acid as catalyst. XRD of acetylated starch revealed that there was loss of crystallinity with increasing DS. The carbonyl group signal at 1750 cm⁻¹ appeared in the FTIR spectra. The intensity of this peak increased whereas the intensity of the hydroxyl groups at 3000–3600 cm⁻¹ decreased. The thermal behavior of the samples was investigated and the results showed that the acetylation decreased the gelatinization temperatures and ΔH_gel, and thermal stability of high DS acetylated starch (DS = 2.82) was much better than that of the original starch and partially substitute starch acetate (DS = 1.52). The SEM suggested that most of the starch granules were disintegrated into many visible fragments along with the increasing of DS. The starch acetate with different DS prepared in this paper has many potential uses in food and pharmaceutical applications for its lower gelatinization temperature and thermal stability properties.     

脉冲电场对木薯醋酸酯淀粉制备及其性质的影响

以木薯淀粉为原料,以乙酸酐为酯化剂,在不同脉冲电场强度(0 k V/cm、2k V/cm、3 k V/cm、4 k V/cm、5 k V/cm、6 k V/cm、7 k V/cm)、不同有效处理时间(0 ms、3 ms、6 ms、9 ms、12 ms、15 ms)和不同酸酐添加量(4%、6%、8%、10%、12%)下湿法制备醋酸酯淀粉,对乙酰基及取代度进行测定,得出经过脉冲电场处理,木薯醋酸酯淀粉乙酰基含量和取代度都有所提高。乙酸酐添加量为6%,电场强度为4 Kv/cm,有效处理时间为9 ms,样品取代度由0.084提高至0.110,说明脉冲电场处理可以促进酯化反应的进行,提高了酯化反应效率。此外还研究了木薯醋酸酯淀粉糊透明度、溶解度及膨润力、冻融稳定性和淀粉糊黏度性质,并通过红外光谱对产品进行结构表征。结果表明:经过脉冲电场处理,木薯淀粉颗粒均引入了乙酰基团,并提高醋酸淀粉的糊透明度、溶解度和膨润力,提高淀粉糊峰值黏度,而淀粉糊稳定性基本保持不变。     

微波法制备硬脂酸木薯淀粉酯

目的建立微波辅助技术制备硬脂酸木薯淀粉酯,并对其理化性质进行表征。方法以木薯淀粉为原料,以硬脂酸为酯化剂,以盐酸为催化剂,通过均匀设计实验并经SPSS 10.0软件优化微波法制备硬脂酸木薯淀粉酯的最佳工艺参数。结果硬脂酸木薯淀粉酯的最佳工艺条件如下:淀粉50 g(干基),微波功率450 W,微波辐射时间1.5 min,盐酸加入量6.0 mL,硬脂酸0.5 g,得到的产品取代度为0.01685。结论本研究建立了一种无污染、反应快、能耗低的硬脂酸木薯淀粉酯制备方法,得到的产品取代度较高,溶解度、乳化性和乳化稳定性均优于原淀粉。     

Gelatinisation Characteristics of Cassava Starch Settled in the Presence of Different Chemicals

Addition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (T_o), temperature at peak minimum (T_p) and end temperature (T_e), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crystallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.     

乙酰化柠檬酸酯化交联机械活化淀粉的制备及性质分析

以机械活化木薯淀粉为原料,醋酸酐为酯化剂,柠檬酸为交联剂,采用溶剂法制备乙酰化柠檬酸酯化交联淀粉,考察了机械活化时间、混合酸添加量、反应温度、反应时间、柠檬酸与乙酸酐质量比等因素对乙酰化柠檬酸酯化交联淀粉沉降积的影响,并对制备得到的酯化交联淀粉进行结构表征及性质测定.结果表明,制备最佳工艺条件为:机械活化时间40 mi...     

Preparation and Characterization of Starch Acetate

Acetylation of native hydrolyzed and oxidized, maize starch has been studied. The different factors affecting acetylation process were investigated. These factors include liquor ratio, acetic anhydride, perchloric acid concentration, reaction time and temperature. Also investigated were characterization and application of the acetylated starches in textile warp sizing. The acetyl content increases to reach a maximum and then decreases on increasing either liquor ratio or perchloric acid concentration. Also it increases with increasing acetic anhydride concentration within the range examined whereas the actylation reaction efficiency % decreases. Hydrolysis of starch prior acetylation inhances the susceptibility of the starch towards acetylation whereas oxidation do the reverse. The solubility of acetylated starches derived from hydrolyzed or oxidized starches increases more than that of acetylated native starch. The solubility depends on the extent of acetylation and of the modification prior acetylation. Acetylation of starch improves its sizeability of cotton yarns.     

酶法制备木薯微孔淀粉的工艺优化

为了优化包埋粉末油脂的木薯微孔淀粉工艺、提高吸附性能,利用糖化酶和α- 淀粉酶对木薯淀粉进行处理,先通过六组单因素试验确定反应时间、反应温度、pH 值、底物浓度、酶浓度以及糖化酶和α- 淀粉酶配比最佳范围,再通过L18(37)正交试验,研究这些因素对木薯微孔淀粉吸附性能的影响。结果表明,当反应时间7h、温度60℃、pH6.0、底物浓度40%、酶浓度2.5%、糖化酶和α- 淀粉酶配比为1:4(m/m)时制备的木薯微孔淀粉的吸附性能最佳,木薯微孔淀粉对油脂的吸附性与原淀粉相比,从11.5% 提高到52%,提高了4.52 倍。     

木薯羧甲基淀粉的机械活化固相化学法制备、表征及其特性

以木薯淀粉为原料,氯乙酸钠为醚化剂,氢氧化钠为催化剂,采用机械活化固相化学反应法制备羧甲基淀粉。以取代度为评价指标,通过单因素和正交试验设计优化确定最佳制备工艺,采用傅里叶红外光谱（Fourier transform infrared spectroscopy,FTIR）、X-射线衍射（x-ray diffraction,XRD）、扫描电镜（scanning electron microscope,SEM）对羧甲基淀粉的结构进行表征,并考察羧甲基淀粉的理化特性。结果表明,最佳工艺参数为淀粉与氯乙酸钠物质的量比1∶1、反应温度50?℃、反应时间1.5?h、氢氧化钠溶液质量分数18.8%、搅拌速率380?r/min、球磨介质堆体积500?mL,在此条件下制备的羧甲基淀粉取代度为0.540?1。FTIR、XRD、SEM检测进一步证实木薯淀粉发生了羧甲基化反应。理化特性结果显示,羧甲基淀粉的黏度升高,溶解度增大,吸水性、保水性、冻融稳定性、抗酸碱性、抗酶解性等均得到较好的提高。