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 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.     

乙酰化香蕉淀粉的特性

通过与玉米淀粉比较,乙酰化香蕉淀粉的灰分、蛋白质、脂肪含量均比乙酰化玉米淀粉高.乙酰化香蕉淀粉糊的透明率在低温下出现较小的退化趋势,但常温下淀粉糊的透明率较高且有较好的稳定性.在较高温度下,乙酰化香蕉淀粉的持水能力比原淀粉高.乙酰化作用增加淀粉的溶解度和膨胀率.乙酰化作用也增加了香蕉淀粉糊的粘度值.     

Properties of retrograded and acetylated starch preparations: Part 1. Structure, susceptibility to amylase, and pasting characteristics

The aim of the study was to produce a retrograded starch preparation from potato starch using various methods, to modify it by acetylation, and then to estimate the effect of these modifications on its selected properties. The chemical structure of modifiers and the degree of substitution achieved with acetic acid were determined by nuclear magnetic resonance (NMR). The resistance of starch to amyloglucosidase and digestive amylases was determined as well. Also, the thermal characteristics of gelatinization of the starch preparations were studied by differential scanning calorimetry (DSC); the method of starch paste production was investigated by a Brabender viscograph, and morphological and structural differences were visualized using scanning electron microscopy (SEM). Retrograded starch preparations were porous and stratified in structure; with their properties resulting from the method of their production. Their chemical structure did not differ from that of native starch, but they displayed a different course of pasting characteristics and increased susceptibility to acetylation as well as resistance to amylases (by approximately 10 g/100 g). Acetylation contributed to a decrease in the temperature of reaching maximum viscosity, an increase in the maximum viscosity, and a decrease in the amount of heat needed for thermal transition of the produced preparations. Acetylated retrograded starch was characterized by a higher degree of substitution and an increased activity of acetyl groups substituted at carbon atoms 2 and 3 compared to the acetylated native starch, thereby triggering a significant increase in resistance to amylases (approximately 40 g/100 g). Combining the resistance of starch samples RS3 and RS4 may be a new method to obtain resistant starch from potato starch.     

海藻酸钠对木薯淀粉糊性质影响

该研究从糊化过程、膨胀度、溶解度、动态粘弹性几个方面探讨海藻酸钠对木薯淀粉糊性质影响。Brabender结果显示,添加海藻酸钠后,起始糊化温度降低,峰值粘度和崩解值升高;海藻酸钠存在促进膨胀度增加,降低溶解度;动态粘弹性结果表明,添加海藻酸钠使储能模量(G')和tanδ增高。     

Structural and rheological properties of potato starch affected by degree of substitution by octenyl succinic anhydride

The objective of the present study was to investigate the structural and rheological properties of octenyl succinic anhydrate (OSA) modified potato starch. Potato starch was modified with different concentrations of OSA (0, 1, 3, and 5%, v/v). X-ray results suggested that OSA modification did not disrupt the crystallinity of the native starch, and esterification occurs primarily in the amorphous regions. The use of ¹H-NMR spectra confirmed the presence of methyl protons in substituted OSA groups, which interacted with the starch molecules. In steady shear rheological analysis, OSA modified starch pastes showed a pronounced shear thinning behavior (n = 0.47–0.54). The consistency index (K) and yield stress (σ_oc) values of OSA modified starch pastes were significantly lower than those of the native starch. Dynamic shear rheological tests indicated that OSA modified starch pastes had weak gel-like behavior with storage moduli (G’) higher than loss moduli (G’’). OSA potato starch pastes were more viscous as compared to the native potato starch paste, as evidenced by their higher tan δ values.     

Effect of the production method on the properties of RS3/RS4 type resistant starch. Part 1: Properties of retrograded starch (RS3) produced under various conditions and its susceptibility to acetylation

The objective of this study was to establish the effect of the concentration of a starch paste subjected to freezing on the properties of the produced retrograded starch, and to determine its susceptibility to acetylation with acetic acid anhydride. A starch paste (1, 4, 10, 18 or 30g/100g) was produced from native potato starch that was frozen, defrosted and dried. Al preparations of retrograded starch had the same chemical structure determined with the technique of nuclear magnetic resonance (NMR) and diversified physical form visible on photos taken with an electron microscope (SEM). An increase in the concentration of paste, used to produce the preparations, resulted in decreased: amylose content (from 25.0 to 20.4/100g), solubility in water (from 41.1 to 20.1/100g), swelling power (from 45.0 to 19.3/g), and susceptibility of the preparations to the action of amyloglucosidase (from 95.4 to 83.6/100g). The heat of phase transition of solubilisation determined with differential scanning calorimetry (DSC) ranged from 3.8 to 7.1J/g, and the initial temperature of transition was increasing from 43.4 to 49.7°C along with an increasing concentration of the paste subjected to retrogradation. The 1-10/100g concentration of the paste used to produce preparations was observed to increase, whereas that between 10 and 30/100g to decrease the susceptibility to acetylation and viscosity of the prepared pastes, determined both with a Brabender viscograph and a Haake oscillating-rotational viscosimeter.     

Dynamic Rheological and Thermal Properties of Acetylated Sweet Potato Starch

Dynamic rheological and thermal properties of acetylated sweet potato starch (SPS) pastes (5%, w/w) were evaluated as a function of the degree of substitution (DS). The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH) of acetylated SPS, which were determined using differential scanning calorimetry, were lower than those of native starch, and significantly decreased with an increase in DS. Magnitudes of storage modulus (G′), loss modulus (G′′) and complex viscosity (η*) of acetylated SPS pastes were determined using a small‐deformation oscillatory rheometer. Dynamic moduli (G′, G′′ and η*) values of acetylated SPS pastes except for 0.123 DS were higher than those of native starch, and they also decreased with an increase in DS. The tan δ (ratio of G′′/G′) values (0.37–0.39) of acetylated SPS samples were lower than that (0.44) of native starch and no significant differences were found among acetylated SPS samples, indicating that the elastic properties of SPS pastes were affected by acetylation but did not depend on DS. The G′ values of acetylated SPS during aging at 4°C for 10 h were much lower than those of native starch, showing that the addition of acetyl groups produced a pronounced effect on the retrogradation properties of SPS.     

Effect of Acetylation on Some Properties of Corn and Potato Starches

Corn starch and starches separated from different potato cultivars were acetylated to evaluate the effect of plant source on the physicochemical, morphological, thermal, rheological, textural and retrogradation properties of the starches. Corn starch showed a lower degree of acetylation than potato starches under similar experimental conditions. The degree of acetylation for different potato starches also differed significantly. Morphological examination revealed that the granules of acetylated Kufri Chandermukhi and Kufri Sindhuri starches tended to appear as fused and less smooth than native starch granules. Acetylation of corn and potato starches decreased the transition temperatures and enthalpy of gelatinization and increased swelling power and light transmittance. However, the change in these was greater in the potato starches with higher percentage of small sized granules. Acetylated starches showed higher peak G', G'' and lower tan δ than their counterpart native starches during heating. Among the starches from different cultivars, the change in the rheological parameters after acetylation differed to a significant extent. The retrogradation was observed to be negligible in the acetylated cooked starch pastes. Results implied that the change in functional properties of starches with acetylation depends on source and granule morphology of native starch.     

Hydrothermal Modifications of Tropical Tuber Starches. 1. Effect of Heat‐Moisture Treatment on the Physicochemical,Rheological and Gelatinization Characteristics

Cassava, sweet potato and arrowroot starches have been subjected to heat‐moisture treatment (HMT) under different conditions using a response surface design of the variables. A comparative study was performed on the pasting properties, swelling behaviour and the gelatinization properties of the modified starches and also on the rheological and textural properties of their pastes. X‐ray diffraction studies have shown that cassava starch exhibited a slight decrease in crystallinity, whereas sweet potato and arrowroot starches showed an increase in crystallinity after HMT at 120ºC for 14 h with 20% moisture. The swelling volume was reduced and the solubility was enhanced for all three starches after HMT, but both effects were more pronounced in the case of arrowroot starch. The decrease in paste clarity of the starch after HMT was higher in the case of cassava and sweet potato starches. Viscosity studies showed that the peak viscosity of all three starches decreased after HMT, but the paste stability increased as seen from the reduced breakdown ratio and setback viscosity. Studies on rheological properties have shown that storage and loss moduli were higher for the starches heat‐moisture treated at higher moisture and lower temperature levels than the corresponding native starches. Storage of the gel at ‐20ºC resulted in a significant increase in storage modulus for all the three starches. All the textural parameters of the gels were altered after the treatment which depended on the nature of the starch and also the treatment condition.     

冻融循环次数对超声改性玉米淀粉凝胶特性和结构的影响

探讨经超声处理的玉米淀粉在冻融循环过程中其凝胶特性和结构的变化,以期为提升速冻淀粉基食品品质提供理论指导。利用流变仪、物性分析仪、低场强核磁共振仪、傅里叶变换红外光谱仪及X射线衍射仪,分析冻融循环次数对超声改性玉米淀粉凝胶动态流变学和质构特性的影响,并对其结构进行表征。结果表明：不同冻融循环次数下,以天然玉米淀粉作对照,超声改性玉米淀粉凝胶的析水率在第4次冻融时显著下降了5.19%(P<0.05),提高了冻融稳定性;超声改性玉米淀粉凝胶的储能模量和损耗模量降低,凝胶强度变弱;硬度在第4次冻融时显著降低了10.83%(P<0.05),直链淀粉含量下降了0.15%;超声改性玉米淀粉凝胶的碘结合力减弱,横向弛豫时间分布曲线整体左移,短程有序结构减弱,相对结晶度降低。综合凝胶特性和结构表征结果,表明超声处理能够抑制冻融循环过程中玉米淀粉凝胶体系中的水分迁移和双螺旋结构的形成,改善其冻融稳定性。     

Studies on the synthesis and properties of hydroxypropyl derivatives of cassava (Manihot esculenta Crantz) starch

Cassava starch was subjected to hydroxypropylation in three different media, which included water, water in the presence of a phase transfer catalyst, and 2‐propanol, all at 30 ± 2 °C for 24 h. Propylene oxide was used in four different concentrations (50, 100, 150 and 200 g kg^?1 of starch dry weight). The products were characterized by determining their molar substitution (MS), structural and functional properties. The analyses were done in triplicate and the data were analyzed using the statistical package 8.01. The MS of the products ranged from 0.26 to 1.41. The MS of the hydroxypropyl derivatives were found to be higher when the reaction was carried out in the aqueous medium in the presence of tetrabutylammonium bromide, a phase transfer catalyst, when compared to the reaction in 2‐propanol, which was found to be not very effective at 30 ± 2 °C. The etherification altered the granular properties of starch, as could be seen from scanning electron micrographs. Hydroxypropylation resulted in starch pastes which were stable and with higher swelling volume, solubility, light transmittance and water binding capacity as compared to native starch. The hydroxypropyl starches showed significantly lower pasting temperatures and setback viscosities. The enzyme digestibility of the derivatives was seen to decrease with increase in MS and there was a significant reduction in the syneresis of the starch pastes of hydroxypropyl derivatives. Texture profile analysis showed that hydroxypropylated starch gels exhibited higher hardness, springiness (elasticity) and gumminess and lower cohesiveness than the native starch. Copyright © 2007 Society of Chemical Industry     

Physicochemical characterization of chemically modified corn starches related to rheological behavior,retrogradation and film forming capacity

An integral approach of chemical modification effects on physicochemical and functional properties of corn starch was performed using different and complementary techniques. Acetylated, acetylated crosslinked, hydroxypropylated crosslinked, and acid modified corn starches were analyzed. Substitution and dual modification reduced significantly amylose concentration. Chemical modification decreased granules crystallinity degree. A significant increase in swelling power was observed in substituted and dual modified starches at 90 °C, besides these treatments decreased gelatinization temperature and enthalpy. Acid modified starch pastes showed a Newtonian behavior while substituted and dual modified ones exhibited a viscoelastic response. Dynamic rheological properties of modified starch pastes were not affected by post gelatinization time while native starch pastes developed a more rigid structure during storage. Retrogradation of substituted starch pastes after 12 days at 4 °C was reduced, since syneresis degree and hardness increase were significantly lower than those of native pastes. It was demonstrated that only substituted and native starches exhibited film forming capacity.     

Spectral analysis and physical properties of benzylated starch

A‐ and B‐wheat starch (in native or acetylated form) and potato starch (slightly acetylated) were subjected to benzylation with benzylchloride in various reaction conditions and at various reaction times (40–100°C, 1–90 h). Modified and original starches were characterized by elemental analysis and spectroscopic methods (FT‐IR and 1H NMR). The semicrystalline or amorphous character was indicated by X‐ray powder (XRD) patterns. Rheological properties of benzyl starch of DS ∼ 1 were measured by small amplitude oscillation shear rheology (SAOS) using the rheometer Haake Rheostress RS 80. The results indicated predominantly elastic behavior because the storage modulus was higher than the loss modulus over the whole frequency range; it corresponded to a true gel. The storage and loss moduli increased with increasing frequency while the tangent of phase did not change and was approximately δ = 40°.     

Development of oxidised and heat-moisture treated potato starch film

This study investigated the effects of sodium hypochlorite oxidation and a heat-moisture treatment of potato starch on the physicochemical, pasting and textural properties of potato starches in addition to the water vapour permeability (WVP) and mechanical properties of potato starch films produced from these starches. The carbonyl contents, carboxyl contents, swelling power, solubility, pasting properties and gel texture of the native, oxidised and heat-moisture treated (HMT) starches were evaluated. The films made of native, oxidised and HMT starches were characterised by thickness, water solubility, colour, opacity, mechanical properties and WVP. The oxidised and HMT starches had lower viscosity and swelling power compared to the native starch. The films produced from oxidised potato starch had decreased solubility, elongation and WVP values in addition to increased tensile strength compared to the native starch films. The HMT starch increased the tensile strength and WVP of the starch films compared to the native starch.     

酶促合成肉豆蔻酸淀粉酯的性质及结构表征

为提高淀粉的反应活性,采用氢氧化钠尿素法对马铃薯原淀粉进行处理,以处理后的马铃薯淀粉和肉豆蔻酸为原料,Novozyme 435为催化剂,在无溶剂体系中制备了取代度为0.018~0.065的肉豆蔻酸淀粉酯,并对其部分理化性质进行研究。结果表明:与原淀粉相比,预处理淀粉溶解度和透明度显著增加(P0.05),其膨胀度、冻融稳定性、乳化性和乳化稳定性均显著降低(P0.05)。同时,肉豆蔻酸淀粉酯的性质与其取代度密切相关,与原淀粉相比,随着取代度的增加,酯化淀粉冻融稳定性、乳化性和乳化稳定性随之升高,而其溶解度、膨胀度和透明度随之下降。扫描电子显微镜(SEM)、傅里叶红外光谱分析(FTIR)、疏水性测定对预处理淀粉及不同取代度的肉豆蔻酸淀粉酯进行观察、测定、分析,结果表明,淀粉颗粒结构被破坏,酯化淀粉具有较好的疏水性,FTIR验证了预处理淀粉及酯化淀粉的生成。     

Physicochemical properties of acetylated starches from some Indian kidney bean (Phaseolus vulgaris L.) cultivars

Starches separated from four kidney bean cultivars were modified by acetylation to reduce retrogradation and increase gel stability and compared with respective native starches (data of native starch reported by Wani et al., 2010 ). Acetylation was carried out by treating starches with 0.04 and 0.08 g of acetic anhydride per gram of starch dry weight basis (dwb) at 25 °C and pH between 8.0 and 8.5. The extent of acetylation increased proportionally with the concentration of acetic anhydride used. The pasting curves of 10.7% starch determined by Rapid Visco Analyzer at 160 rpm showed that acetylation decreased the setback viscosity values by 0.64–34.58% and pasting temperature by 4.4–9.2 °C when compared with the native starch. Differential scanning calorimetry observations also revealed significant (P ≤ 0.05) decrease in gelatinisation temperature of acetylated starches than the corresponding native starches. Hardness of starch gels varied between 14.3 and 44.0 g, which was significantly (P ≤ 0.05) lower than the corresponding native starch gels.     

Zur genaueren Kenntnis durch Temperatureinfluß modifizierter Wachsmais- und Amylosestärke

Contribution on Waxy Maize Starch and High Amylose Starch Modified under the Influence of Temperature. The starches of the two genetic varieties of the corn grain, waxy maize starch and high amylose starch, were subjected to the influence of different temperatures. Subsequently, the physico-chemical properties of the modified starches were examined. Waxy maize starch which mainly consists of amylopectin, and high amylose starch which contains a high portion of linear chains of polymerized glucose units are interesting test materials because of their properties which are different by nature. Waxy maize starch with its high viscosity values, great swelling power and good solubility in hot water shows no tendency to settle or retrograde. While the process of freezing the starch granules hardly changes the properties mentioned, the influence of a temperature of 100°C causes morphological changes of a small proportion of grains, including the loss of birefringence. These changes are particularly pronounced after treatment of native starch at 120°C. The properties of the starch pastes were also strongly changed. The native high amylose starch characterized by unusual, oblong starch granules without birefringence, a low viscosity, low swelling power and low solubility showed only minor changes after freezing, whereas a temperature of 100°C resulted in reduced values of solubility and aggregation of the starch granules. A temperature treatment at 120°C and at 125°C brought about changes in the swelling properties, the viscosity and limiting viscosity, settling, swelling power, and solubility of the starch pastes. Attempts were made to conform the changes in the different properties observed with the expected influence of temperature treatment on the intermolecular forces (hydrogen bonds, crossbonding).     

Rheological,thermal and microstructural properties of whey protein isolate‐modified cassava starch mixed gels at different pH values

The objective of this study was to investigate the rheological, thermal and microstructural properties of whey protein isolate (WPI)‐hydroxypropylated cassava starch (HPCS) gels and WPI‐cross‐linked cassava starch (CLCS) gels at different pH values (5.75, 7.00 and 9.00). The rheological results showed that the WPI‐modified starch gels had greater storage modulus (G?) values than the WPI‐native cassava starch gels at pH 5.75 and 7.00. Differential scanning calorimetry curves suggested that the phase transition order of the WPI and modified starch changed as the pH increased. Scanning electron microscopy images showed that the addition of HPCS and CLCS contributed to the formation of a compact microstructure at pH 5.75 and 7.00. A comprehensive analysis showed that the gelling properties of the WPI‐modified starch were affected by the difference between the WPI denaturation temperature and modified starch gelatinisation temperature and by the granular properties of the modified starch during gelatinisation. These results may contribute to the application of WPI‐modified starch mixtures in food preparation.     

Resistant Starch‐rich Powders Prepared by Autoclaving of Native and Lintnerized Banana Starch: Partial Characterization

Powdered preparations enriched in resistant starch (RS) were obtained from native and lintnerized (prolonged acid treatment) banana starches by consecutive autoclaving/cooling treatments. The preparations were tested for indigestible starch content, swelling and solubility properties, thermal analysis and pasting profile. The autoclaved samples had higher RS content than their parental counterparts, but the chemical modification (lintnerization process) allowed development of higher RS proportions (19%, dry matter basis, dmb). The autoclaved samples (RS‐enriched products) showed similar swelling values (α = 0.05) at the temperatures assessed. These RS‐rich products exhibited a lower solubility in water than the corresponding raw materials. The peak temperatures of the thermal transition were 155.5 and 145.8°C for native autoclaved and lintnerized autoclaved starch, respectively. These values indicate that RS products have a marked thermal stability. The pasting behavior of the RS products was less pronounced than that of the raw counterparts. Hence, their potential use as processed food ingredients should not impact final product viscosity. These RS‐enriched products appear suitable for the formulation of functional foods.