Physicochemical Characterization of Resistant Starch Type-III (RS3) Obtained by Autoclaving Malanga (Xanthosoma sagittifolium) Flour and Corn Starch

The feasibility of obtaining resistant starch type III (RS3) from malanga flour (Xanthosoma sagittifolium), as an unconventional source of starch, was evaluated using the hydrothermal treatment of autoclaving. The physicochemical characterization of RS3 made from malanga flour was carried out through the evaluation of the chemical composition, color attributes, and thermal properties. In addition, the contents of the total starch, available starch, resistant starch, and retrograded resistant starch were determined by in vitro enzymatic tests. A commercial corn starch sample was used to produce RS3 and utilized to compare all of the analyses. The results showed that native malanga flour behaved differently in most of the evaluations performed, compared to the commercial corn starch. These results could be explained by the presence of minor components that could interfere with the physicochemical and functional properties of the flour; however, the RS3 samples obtained from malanga flour and corn starch were similar in their thermal and morphological features, which may be related to their similarities in the content and molecular weight of amylose, in both of the samples. Furthermore, the yields for obtaining the autoclaved powders from corn starch and malanga flour were similar (≈89%), which showed that the malanga flour is an attractive raw material for obtaining RS3 with adequate yields, to be considered in the subsequent research.     

Effects of Variety and Growing Location on Physicochemical Properties of Starch from Sweet Potato Root Tuber

Three sweet potato varieties with purple-, yellow-, and white-fleshed root tubers were planted in four growing locations. Starches were isolated from their root tubers, their physicochemical properties (size, iodine absorption, amylose content, crystalline structure, ordered degree, lamellar thickness, swelling power, water solubility, and pasting, thermal and digestion properties) were determined to investigate the effects of variety and growing location on starch properties in sweet potato. The results showed that granule size (D[4,3]) ranged from 12.1 to 18.2 μm, the iodine absorption parameters varied from 0.260 to 0.361 for OD620, from 0.243 to 0.326 for OD680 and from 1.128 to 1.252 for OD620/550, and amylose content varied from 16.4% to 21.2% among starches from three varieties and four growing locations. Starches exhibited C-type X-ray diffraction patterns, and had ordered degrees from 0.634 to 0.726 and lamellar thicknesses from 9.72 to 10.21 nm. Starches had significantly different swelling powers, water solubilities, pasting viscosities, and thermal properties. Native starches had rapidly digestible starch (RDS) from 2.2% to 10.9% and resistant starch (RS) from 58.2% to 89.1%, and gelatinized starches had RDS from 70.5% to 81.4% and RS from 10.8% to 23.3%. Two-way ANOVA analysis showed that starch physicochemical properties were affected significantly by variety, growing location, and their interaction in sweet potato.     

Isothermal microcalorimetric studies on starch retrogradation

In the present study, isothermal microcalorimetry was introduced as a tool to investigate properties of starch retrogradation during the first 24 h. The study was made on purified amylose and amylopectin from corn, as well as on native starches, such as wheat, potato, maize, waxy maize and amylomaize, differing in their amylose content. The results were obtained in the form ofP-t traces (thermal powervs. time), and integration of these traces gave a net exothermic enthalpy of reaction, caused by the crystallization of amylose and amylopectin. TheP-t traces reflected the quantities of amylose and amylopectin in the starch studied. Depending on the amylose content and the botanical source of the starch, the rate of crystallization of amylose was high and predominated over that of amylopectin during the first 5–10 h. The contribution from amylose crystallization to the measured exothermic enthalpy was very substantial during this period. After 10 h, amylose crystallized at a lower constant rate. During the first 24 h, amylopectin crystallized at a low steady rate. The exothermic enthalpies obtained by the isothermal microcalorimetric investigations during the first 24 h of retrogradation were generally low in relation to the endothermic melting enthalpies observed by differential scanning calorimetry (DSC) measurements after 24 h of storage. The discrepancies in enthalpy values between the two methods are discussed in relation to phase separation and the endothermic effects owing to the decrease in polymer-water interactions when polymer-rich regions in the starch gel separate. Besides the exothermic enthalpies obtained, theP-t traces also made it possible to study the initial gelation properties of amylose from different botanical sources. The present study further demonstrated that isothermal microcalorimetry can provide a possible way to investigate the antistaling effect of certain polar lipids, such as sodium dodecylsulphate (SDS) and 1-monolauroyl-rac-glycerol (GML), when added to starches of different botanical origin. The net exothermic heat of reaction for starch retrogradation during the first 24 h was decreased when GML or SDS was added to the starch gels. The recordedP-t traces also showed how the effect of the added lipid influenced different periods during the first 24 h of starch retrogradation, and that the effect depended mainly on the amylose content, the botanical source of the starch, and the type of lipid used. When GML or SDS was added to waxy maize, the isothermal microcalorimetric studies clearly indicated some interaction between amylopectin and the polar lipids. These results concerning the action of anti-staling agents are further discussed in relation to the helical inclusion complexes formed between amylose-polar lipid and amylopectin-polar lipid.The authors thank Eva Qvarnström at the Dept. of Thermochemistry and Eva Tjerneld at the Dept. of Food Technology for valuable practical assistance. Financial support was obtained from the Swedish Council for Forestry and Agricultural Research (SJFR) and the Swedish Farmer's Foundation for Agricultural Research (Stiftelsen Lantbruksforskning).     

Electrosprayed maize starch and its constituents (amylose and amylopectin) nanoparticles

Starch consists of amylose and amylopectin. Properties such as being natural and highly hygroscopic as well as biodegradability have opened a considerable range of applications for amylose, amylopectin and starch. The performance of particles is highly dependent on their size which in turn determines the specific surface area. This work studies the application of electrospraying to fabricate maize starch and its constituents: amylose and amylopectin nanoparticles. This study showed that electrospraying technique is capable of producing amylose, amylopectin and starch nanopowder with an average particle size around 100 nm. FTIR analysis showed no reaction or interaction occurring in amylose, amylopectin and starch nanoparticle compared with their natural form. Basically, lower concentration, lower viscosity and lower surface tension of the electrospraying solution as well as higher nozzle–collector distance, higher voltage and lower feed rate lead to smaller nanoparticle size. Copyright © 2015 John Wiley & Sons, Ltd.     

Effect of gamma irradiation on the thermal and rheological properties of grain amaranth starch

Physical properties of starch from two cultivars of gamma-irradiated grain amaranth with different amylose content were investigated. Pasting viscosities decreased continuously with the increase in dosages of irradiation. Furthermore, different irradiation dosages resulted in modification of the thermal properties and crystallinity of starch. Dynamic oscillation on shear was also employed, temperature and frequency sweeps showed that changes in storage modulus and loss modulus were significant, with Tibet Yellow producing more elastic gels as compared to Hy030 at different irradiation dosages.     

Understanding amylose crystallinity in starch–clay nanocomposites

The amylose–water interaction is part of an important equilibrating process within the starch matrix leading to slow recrystallization of amylose chains and growth of anisotropic properties in the starch matrix. This article highlights the influence of nanoclay on (a) the structural development of amylose crystallinity and (b) the rate of water loss from the starch matrix. By varying the nanocomposites level (1.5–4 wt %), a unique microstructure is obtained that “locks” moisture and it was found that on a per unit weight basis of the starch matrix, addition of 4 wt % nanoclay resulted in additional 8.5% water in the matrix. Also, it was found that increasing the nanoclay from 2 to 4% by weight, the composite modulus jumped by 100% indicating excellent interaction between clay nanocomposites and starch polymer. Analysis of the starch crystallinity data indicates that nanocomposites retard the mobility of the starch molecules (specially the long chain amylose component) to restrict the movement of “associated” water around starch and this increases the “locked” water by ～10%. The results strongly suggest that a new structural unit may be formed by amylose–water–clay interaction which enhances the composites properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 979–987, 2008     

Preparation and Characterisation of Thermoplastic Starches from Cassava Starch,Cassava Root and Cassava Bagasse

Summary: Thermoplastic starches (TPS) based on cassava starch have been produced by extrusion at 120 °C, using glycerol as plasticizer. Three forms of cassava starch were employed, viz: cassava root (CR), cassava bagasse (CB) and purified cassava starch (PCS). The main differences between these are the presence of sugars and a few fibres in CR and high fibre concentration in CB. Conditions of processing and characteristics such as amylose and fibre content, crystallinity, water absorption and mechanical behaviour in the tension x deformation test were evaluated. The results demonstrated that the PCS and CR had amylose contents consistent with literature values (14–18%) and that CB is a material constituted mainly by amylopectin. It was found that fibres in high proportions (as in the bagasse) can confer reinforcement properties and are thus able to generate natural composites of TPS with cellulose fibre. The sugars naturally found in the root reduce the elongation of the TPS under tension. The PCS and CR TPS were stable with respect to indices of crystallinity after processing; and during a period of 90 d in a relative humidity of 53%, while the CB TPS tended to vary its crystallinity, probably because its amylose chain had low degree of polymerization.     

Construction of Porous Starch-Based Hydrogel via Regulating the Ratio of Amylopectin/Amylose for Enhanced Water-Retention

The performance of hydrogels prepared with traditional natural starch as raw materials is considerable; the fixed ratio of amylose/amylopectin significantly limits the improvement of hydrogel structure and performance. In this paper, starch hydrogels were prepared by physical blending and chemical grafting, with the aid of ultrasonic heating. The effects of different amylose/amylopectin ratios on the microstructure and water retention properties of starch hydrogels were studied. The results show that an increase in amylopectin content is beneficial to improve the grafting ratio of acrylamide (AM). The interaction between the AM grafted on amylopectin and amylose molecules through hydrogen bonding increases the pores of the gel network and thins the pore walls. When the amylopectin content was 70%, the water absorption (swelling 45.25 times) and water retention performance (16 days water retention rate 44.17%) were optimal. This study provides new insights into the preparation of starch-based hydrogels with excellent physical and chemical properties.     

药物控释载体醋酸酯淀粉的消化性能研究

采用生物体外(in-vitro)消化模型模拟人体消化道环境，对不同取代度的醋酸酯化木薯淀粉的消化速率进行了研究；用微生物酶对醋酸酯化木薯淀粉进行生物降解并测定各个样品的抗消化淀粉含量。结果表明醋酸酯化会增大淀粉颗粒的消化速率，但随取代度的提高消化速率呈下降趋势。同样随取代度的提高，醋酸酯化也会降低淀粉糊的消化速率。醋酸酯淀粉卡抗消化淀粉含量低于原淀粉，且取代度越高含量越低。醋酸酯化会破坏和抑制淀粉中抗消化淀粉的形成。     

Structure of starches extracted from near isogenic wheat lines

Differential scanning calorimetry (DSC), acidic hydrolysis and different physico-chemical approaches were used to study thermodynamic and structural characteristics of starches from near-isogenic wheat lines to establish the effect of different combinations of active granule-bound starch synthase isoforms, taking part in amylose biosynthesis, on the structure and thermodynamic properties of starches. Obtained results suggest that the effect of different GBSS I combinations is realized through altered amylose localization within starch granules, reflecting in changes of melting temperature of crystalline lamellae (T _m) and rates of acidic hydrolysis. It has also been demonstrated that changes in T _m values for native wheat starches are determined by amylose content in amylopectin clusters.     

The Polarized Light-Induced Enzymatic Formation and Degradation of Biopolymers

Summary: White, linearly polarized transformed starch amylopectin into amylose. Moreover, it activated α-amylolysis of starch, hydrolysis of xylane with xylanase, hydrolyses of chitin with chitinase, chitosan with chitosanase, and, interestingly, influenced production of cyclodextrins with cyclodextrin glycosyltransferase. Effect of duration of illumination of cyclodextrin glucosyltransferase with polarized light had certain effect upon the yield and isomer ration of three isomeric cyclodextrins. Application of the polarized light required 1–2 hour illumination of the enzymes in a small reaction vessel followed by admixture of so activated enzymes to a bioreactor. Further reactions did not require any illumination.     

Structure of starches extracted from near-isogenic wheat lines

High-sensitivity differential scanning calorimetry (HSDSC) and small-angle X-ray scattering (SAXS) were used to investigate the structural characteristics of starch granules with different amylose content extracted from near-isogenic wheat lines with different combinations of active granule-bound starch synthase (GBSS I) isoforms. Paracrystalline diffraction model, ‘two-state’ model of starch melting and other physico-chemical approaches were used to estimate the sizes of amylopectin clusters, the thicknesses of crystalline lamellae and the structure of amylopectin defects for investigated wheat starches. The joint analysis of SAXS and DSC data has shown that the size of amylopectin cluster, the thickness of crystalline lamellae and the structure of amylopectin defects do not depend on the differences in combinations of active GBSS I isozymes. The data obtained supposed that the amylopectin cluster size and the thickness of crystalline lamellae are, generally, the universal structural parameters for wheat starches. Additionally, the data obtained suggest that increase of amylose content is accompanied by accumulation of both amylose tie-chains, located as defects in crystalline lamellae, and amylose chains oriented transversely to the lamella stack within amorphous lamellae. Disordered ends of amylopectin double helices and/or pre-existing double helices not participating in formation of crystals are considered as amylopectin defects arranged in crystalline lamellae. The relationship between structure of wheat starches extracted from near-isogenic lines and their thermodynamic properties was recognized.     

Structural and mechanical properties of edible films from composite mixtures of starch,dextrin and different types of chemically modified starch

Abstract

Recent regulations restricting the use of one-use-plastics open the possibility to develop starch-based edible packaging material. The objective of this work was to determine the effect of three different modified starches on starch and dextrin composite edible films by a mixture design approach on edible films’ mechanical properties. The amylose content of chemically modified starches influenced their swelling capacities, where higher amylose content was inversely related to water-power uptake and directly related to film thickness. CMS3 Nifrastarch-TS edible films, with higher amylose content, presented higher puncture force and tensile strength, but lower puncture deformation and elongation, related to a less smooth surface, according to atomic force micrographs. The use of CMS1 Gelamil-100, with lower amylose content, decreased stiffness but increased films’ stretching, presenting higher surface smoothness film topography. The use of commercial chemical modified starches in combination with starch and dextrin will allow to control of edible film thickness and hence, mechanical properties, depending on food covering necessities.     

In vitro and in vivo digestibility of native maize starch granules varying in amylose contents

Digestibility of maize starch granules with different amylose content (AL-0, 22, 54, 68, 80, or 90%) was investigated. Measurement of the in vivo resistant starch (RS) content of the starches was performed using surgically prepared ileorectostomized rats. The rats were fed a purified diet containing one of the starches at 652.5 g/kg diet. The in vivo RS content was determined based on the fecal starch excretion. The dietary fiber (DF) value increased as a function of the amylose content in the starch and showed a positive linear correlation with the gelatinization temperature of the granules. In contrast, the in vitro RS content was likely to depend on both the surface area and amylose contents of the starch granules. The maximum in vitro RS content was obtained with AL-68 (54.4%). In vivo RS content showed a significant correlation with the amount of in vitro RS but not in respect to the DF detected. The in vivo RS content of AL-68 (43.4%) was higher than that found in AL-90 (37.8%). A profound gap was observed for AL-54 between the amount of DF (6.4%) and RS (in vitro = 46.6% and in vivo = 40.9%) present. The results suggest that both in vitro and in vivo digestibility of maize starch is affected by the amylose content and surface area of the granules. The current evaluation suggests that the physiological occurrence of RS from maize starch might be predictable by reference to the in vitro RS value.     

Transient entanglements and clusters in dilute polymer solutions

A convenient method to monitor polymer dissolution is to measure the pressure drop created by passing a polymer solution through a capillary constriction rheometer. In this work, we studied the dissolution of polyethylene oxide (PEO) and cationic starch (C‐starch). We found that for freshly dissolved and entangled PEO, the main contribution to the overall pressure drop is due to the contraction and expansion of PEO entanglements at the entrance and exit of the capillary, and that the friction in the capillary plays a minor role. On the other hand, for well‐dissolved PEO, because of the absence of PEO entanglements, the loss of pressure is mainly due to friction. At high velocities the contraction and expansion coefficient for freshly dissolved PEO was more than 20 times higher than for well‐dissolved PEO, resulting in a three times higher overall pressure drop. C‐starch consists of amylopectin (～ 85%) and amylose and is known to contain clusters when freshly dissolved, likely formed from the globular amylopectin molecules. For C‐starch, the main contribution to the overall pressure drop is due to friction. Entrance and exit effects contribute only 10% to the overall pressure drop, which might be due to the linear amylose molecules in C‐starch. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 253–262, 2008     

Effect of Resistant Starch on Hydrolysis and Fermentation of Corn Starch for Ethanol

Starch samples with 0% or 30% amylose were subjected to four different liquefaction enzyme treatments (at various temperature and pH conditions) followed by simultaneous saccharification and fermentation (SSF). Resistant starch (RS) measurements were conducted for the initial starch sample, after liquefaction and after SSF. Initial RS was higher for 30% amylose starch samples (16.53 g/100 g sample) compared with 0% amylose (0.76 g/100 g sample). Higher initial RS resulted in lower conversion of starch into sugars and lower final ethanol yields. The four enzymes hydrolyzed RS, but in varying amounts. Higher temperature liquefaction hydrolyzed a larger portion of RS, resulting in higher ethanol concentrations and lower final residual solids (non-fermentables), whereas lower temperature liquefaction hydrolyzed a smaller portion of RS and resulted in lower ethanol concentrations and higher final residual solids. Decreases in resistant starch after high temperature liquefaction were 55% to 74%, whereas low temperature liquefaction decreases were 11% to 43%. For all enzyme treatments, RS content of starch samples decreased further after SSF.     

乙酰化淀粉的塑化和性能研究

以乙酰化改性淀粉为基体,甘油为增塑剂,利用哈克旋转流变仪密炼制备热塑性乙酰化淀粉.实验结果表明制备热塑性乙酰化淀粉的甘油/乙酰化淀粉配比应大于30/100(W/W),且随甘油含量增加,热塑性乙酰化淀粉的脆性降低.动态机械热分析(DMTA)显示热塑性乙酰化淀粉包含富甘油和富淀粉两相,乙酰化淀粉和甘油为部分互溶.流变学分析显示淀粉分子间作用力非常强,表现为类固态行为.同时本文对材料的热稳定性进行了初步研究.     

Synthesis, thermal properties, and biodegradability of propyl-etherified starch

High amylose corn starch (HACS) was etherified with 1-bromopropane in dimethyl sulfoxide. The structure of the products was characterized by infra-red and ¹H-NMR spectroscopy. The degree of substitution (DS) on glucose unit calculated from ¹H-NMR spectrum was varied from 0.9 to 2.7 by changing feed ratio of 1-bromopropane to HACS. Thermogravimetric analysis reveals that the etherified HACS has a higher decomposition temperature than unmodified HACS. Differential scanning calorimetry analysis reveals that the etherified starch has a clear glass transition temperature which decreased with increasing DS, and that no melting point is observed. This result demonstrates that the etherified HACS mainly consists of amorphous region. The biodegradation rate decreases with increasing degree of etherification.     

淀粉微球形成过程的介观模拟及实验

以环己烷为油相、淀粉乳液为水相、Span60和Tween60为乳化剂,对淀粉微球的形成过程进行了耗散粒子动力学(DPD)模拟及实验研究.模拟结果表明,淀粉微球的形成过程存在四个阶段,即淀粉与乳化剂分子无规则分散阶段、小聚集体形成阶段、球状聚集体形成阶段和稳定平衡阶段,并且发现油水比是影响聚集体是否能形成球状的关键因素.油水比小于7的条件下,油水两相分离较难,水相呈现片状、十字型状、柱状及椭球状等形状;当油水比增加到8,水相能形成微球且微球粒径随油水比增加而减小.同时实验结果表明,油水比为8时,微球粘连,几乎看不清球状形貌,油水比为10～20时,微球的粒径随油水比的增大而减小.实验结果很好地吻合了模拟结果.     

淀粉作用下沸石晶体的链状组装

采用淀粉辅助水热合成方法,得到了特殊的一维链状纯硅沸石分子筛。结果表明在淀粉作用下,多个分子筛晶粒在晶轴b方向的表面之间存在强的相互作用使得分子筛晶粒沿此方向自组织成一维链状结构,所得材料非常均匀,乙醇的加入会使得这些一维聚集体的侧向团聚增加。