Effect of acetylation and oxidation on some properties of breadfruit (Artocarpus altilis) seed starch

Starch extracted from seeds of Artocarpus altilis (Breadfruit) was chemically modified by acetylation and oxidation, and its functional properties were evaluated and compared with these of native starch. Analysis of the chemical composition showed that moisture content was higher for modified starches. Ash, protein, crude fiber and amylose contents were reduced by the modifications, but did not alter the native starch granules' irregularity, oval shape and smooth surface. Acetylation produced changes in water absorption, swelling power and soluble solids, these values were higher for acetylated starch, while values for native and oxidized starches were similar. Both modifications reduced pasting temperature; oxidation reduced maximum peak viscosity but it was increased by acetylation. Hot paste viscosity was reduced by both modifications, whereas cold paste viscosity was lower in the oxidized starch and higher in the acetylated starch. Breakdown was increased by acetylation and reduced with oxidation. Setback value was reduced after acetylation, indicating it could minimize retrogradation of the starch.     

Effect of graft-copolymerization with poly(acrylamide) on rheological and thermal properties of cassava starch

Graft copolymers of different grafting levels were synthesised by the free radical initiated reaction of cassava starch with acrylamide in presence of ceric ammonium nitrate. The viscosity properties of the native granular starch and the grafted starches were determined using a Rapid visco analyzer (RVA) and rheological properties by frequency sweep test under different conditions using a rheometer. Some of the grafted starches exhibited significantly higher and some others exhibited drastically reduced peak viscosity values irrespective of the percentage grafting. All the grafted starches exhibited very good viscosity stability as evidenced from the highly reduced breakdown and higher final viscosity values in comparison to native cassava starch. Thermal analysis of the pure granular cassava starch and grafted starches was carried out using a differential scanning calorimetry (DSC) and thermogravimetry. DSC studies showed that in comparison to native starch, the grafted starches showed lower temperatures of transition. The thermal stability of cassava starch was enhanced by grafting as observed from the thermogravimetric data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of Semicontinuous and Batch System Ozonation on Wheat and Corn Starches

Wheat starch-water and corn starch-water suspensions (10%; w/w) were exposed to ozone gas by using two different contact systems; semicontinuous and batch systems. In semicontinuous contact mode, fresh ozone was applied to starch suspensions at a concentration of 4.2 mg dissolved ozone L^?1 water for 30 min, while in closed batch contact mode, starch suspensions were stirred with ozone gas at a rate of 60 g/h for 30 min. Gelatinization temperatures and enthalpies of wheat and corn starch were increased in a semicontinuous system. However, no change was observed for the gelatinization characteristics of starch samples ozonated- in batch system. Structures and birefringences of wheat and corn starch ozonated in both semicontinuous and batch operations were not differentiated clearly. Higher lightness and whiteness values were observed for both wheat and corn starch ozonated in semicontinuous system than the controls and ozonated samples in batch system. Corn starch ozonated in semicontinuous system has lower chroma and yellowness values than the others. Total color difference for the samples ozonated in semicontinuous system is significantly different from the samples ozonated in batch system. Semicontinuous ozonation system is more effective on the thermal and color properties of wheat and corn starches than the batch ozonation system.     

Irradiation-modification of starch-containing thermoplastic blends. I. Modification of properties and microstructure

Irradiation-modification of the blends of various starches with a synthetic polymer [poly(ethylene-co-vinyl alcohol)] was carried out using an electron beam. The effect of irradiation on neat starches was studies using gel permeation chromatography. Changes in the thermal and mechanical properties of the blends, as well as in their microstructures, were also evaluated. The data indicate, consistent with other reports in literature, that starch molecules fragment under the effect of ionizing radiation, while the EVOH is relatively unaffected. These substantial (mainly physical) modifications to the starch molecules manifest themselves in changes in the thermal behavior of the blends. Furthermore, the mechanical properties of filaments obtained from molten irradiated pellets were quite different from those of control filaments, at least for some starches. Micrographic examination of some blends indicated a correspondence between a modification in the microstructure of the filaments and a change in their mechanical properties. It seems likely that the enhanced mobility of the fragmented starch molecules in the melt is responsible for these changes in the microstructure and concomitantly, the mechanical properties of the blend. Such an irradiation-based physical modification of starch may be of use in tailoring the properties of commercial blends of starches with synthetic thermoplastics. © 1996 John Wiley & Sons, Inc.     

Effects of differential degree of chemical modification on the properties of modified starches: Sizing

Structural and behavioral properties of modified starch by chemical means such as acidification, acetylation, hydroxypropylation, cross-linking/phosphorylation, maleation/succinylation, cationization, amphoterism, and the effect of differential degree of chemical modification of starches in relation to sizing have been reviewed. Since native starch is relatively latent, it requires modification to alter its structure and introduce essential properties. Factors such as concentration, modifying agents, time, pH, and reaction medium affect the extent of starch modification. The degree of chemical modification (substitution/cross-linking) reflects the level of starch resistance or liability in their applications. The behavior of some modified starch at different DS has specific functionality on the sizing properties of starch. Satisfactorily modified starch size offers good warp yarns that drastically reduce yarn breakages during mechanical operation; hence, increasing productivity. Preference could be made to lower DS/DC of acidified, cross-linked, acetylated, maleated/succinylated, and electro-neutral amphoteric starch for effective sizing while highly hydroxypropylated starch grants good viscosity.     

Influence of the glycerol content and temperature on the rheology of native and acetylated starches during and after gelatinization

Native potato starch was acetylated and characterized. The influence of this chemical modification on different properties of the starch was studied. The characterization included the molecular weight, thermal properties, crystallinity, amylose content, swelling behavior, and pasting and rheological properties. The chemical modification induced small changes in the crystallinity of the starch and a reduction in the gelatinization heat and in the range of temperatures at which it took place. The amylose content was determined for acetylated and native potato starches. The swelling of native granules was higher than the swelling of acetylated potato starch. Regarding pasting behavior, the native and acetylated starches responded in similar ways to changes in the temperature and glycerol content. Finally, the acetylated starch was less pseudoplastic than the native starch. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Porous Mullite Ceramics Formed by Direct Consolidation Using Native and Granular Cold‐Water‐Soluble Starches

In this article, the processing and microstructures of porous mullite bodies prepared by modifying the conventional route of the starch consolidation casting method were studied. The proposed route, called the “soluble route”, involves the use of native starches (i.e., potato, cassava, and corn starches) and a synthesized granular cold‐water‐soluble (GCWS) starch. Stable aqueous mullite‐starch suspensions (0.25 starch volume fraction of 40 vol% total solids) were prepared by mixing. The total starch content was a mixture of ungelatinized native starch and GCWS starch with a 1:10 ratio of GCWS starch to total starch. Steady‐state shear flow properties of the suspensions were analyzed by measuring viscosity. The addition of CGWS starch increased the starting suspension viscosity and thus prevented the particle segregation. Porous mullite bodies were obtained by heating (80°C, 2 h) the suspensions in metallic molds and by drying (40°C, 24 h) and sintering (1650°C, 2 h) the green disks after burning out the starch (650°C, 2 h). Green bodies obtained before and after the burning‐out process, and the sintered disks were characterized with density and porosity measurements (Archimedes method) and microstructural analysis by scanning electron microscopy. The phases generated after the sintering process were determined by X‐ray diffraction analysis, and pore size distributions were studied by Hg‐porosimetry. The obtained results showed that the use of the GCWS starch made the shaping of homogeneous mullite bodies without cracks or deformations possible along with the development of controlled porous microstructures.     

The characterization of granule structural changes in acid-thinning starches by new methods and its effect on other properties

Acid-thinned starches (ATSs) have been prepared directly from hydrochloric acid-modified corn starch. The fracture mechanism of starch granule was investigated using scanning electron microscopy combined with laser particle size analysis. And the extent of ATSs chain was also first characterized using X-ray photoelectron spectroscopy. The properties of ATS were tested by X-ray diffraction, differential scanning calorimetry, thermo gravimetric analysis, and rotational viscometry. Native starch and ATSs exhibit different structures and properties. Amorphous regions of corn starch, located in the interior of the starch granule, are preferentially hydrolyzed and can lead to starch particle fracture. The relative C=O content in the ATSs are increased, indicating that the acid thinning makes the starch molecules shorter, and the fracture extent of the starch molecular chains was 240.86 and 608.97%, respectively. Acid thinning does not change the starch crystal pattern or its basic composition, but it does increase the degree of crystallinity. Compared to the native corn starch, ATSs has a higher gelatinization temperature and a lower enthalpy of gelatinization. The acid thinning treatment drastically reduces the hot paste viscosity of the starch.     

Alcoholic-alkaline treatment of sago starch and its effect on physicochemical properties

Sago starch (Metroxylon sagu) was subjected to an alcoholic-alkaline treatment using varied amounts of sodium hydroxide (NaOH) and a constant amount of ethanol at 35 °C. The cold water-solubility (CWS) of all the sago starches increased with an increase in the concentration of NaOH. For samples with high CWS, the Maltese-cross effect was absent when viewed under a light microscope. These granules were also larger than the native starches and had an indented appearance. The X-ray diffraction pattern changed from a C to a V for starches with high CWS. The amylose content of the treated sago starches increased significantly, whereas the intrinsic viscosity and peak viscosity values for treated starches were lower than the native starches. The gelatinization enthalpy decreased and was not detectable for sago starch with high CWS. It was evident that the alcoholic-alkaline treatment was effective for the production of granular cold water-soluble sago starches.     

Reactive supercritical fluid extrusion for development of moisture resistant starch‐based foams

The main objective of this work was to reduce barriers that prevent the usage of starch‐based foams by understanding the effect and the sequence of dual‐modification of crosslinked (XL) and acetylated (Ac) starch in one continuous supercritical fluid reactive extrusion (SCFX) process on wetting properties, physicochemical properties, and cellular structure of solid foam. The starch was reacted with epichlorohydrin (EPI) and acetic anhydride (Ac) under alkaline conditions in a twin‐screw extruder in the presence of supercritical carbon dioxide (SC‐CO₂). An increase in EPI concentration from 0.00 to 3.00% increased the degree of crosslinking as measured by DSC and confirmed by the quantification of the glucose units in the solution after acid hydrolysis. We observed a reduction of the glucose units from 93.07% for 0.00% EPI to 6.73% when 3.00% EPI was added. With crosslinking/acetylation processing, contact angle was higher for modified starches, indicating that chemical treatments induced dramatic changes in their surface polarity. Compared with native, the contact angle for dual modified starch increased from 43.1° to 91.7° which indicated their lower wettability. The addition of SC‐CO₂, EPI, and Ac to the formulation reduced the density of the extrudates and increased the expansion ratio. The average cell size in the extrudate determined by scanning electron microscopy was also found to decrease from 150 to 34 μm by the addition of the two reagents. Moreover, the dual‐modification of starches provided more hardness and adhesiveness to the extrudates than was observed for the unmodified starches. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

淀粉基食品包装膜材料的研究进展

本文就近些年来淀粉基食品包装膜的研究发展进行了综述。范围涵盖了淀粉的选择,塑化剂及其他添加剂的种类,不同的淀粉改性方法对膜性能的影响。其中直链含量高的淀粉所制备的膜具有较高的强度和较好的阻隔性能;甘油是应用最为广泛的塑化剂;不同的添加剂可以针对膜的不同性能加以改善;针对淀粉本身的缺陷进行改性可以提高其膜性能。     

Modified tapioca starch as a rheology modifier in acrylic dispersion system

Tapioca starch was modified by esterification reaction using octenylsuccinic anhydride (OSA) to use as a rheological modifier. Effect of degree of substitution (DS = 0.01–0.04) of octenyl side chain on rheological properties of modified starch in acrylic dispersion system (ASD) was investigated. At low starch to dry acrylic ratio (0.2:100), shear viscosity at low shear rate of OSA-starch containing ASD system increased when the DS of OSA-starch increased. Thickening ability and thixotropic behavior of modified starches in acrylic dispersion system were studied at various modified starches to dry acrylic ratios (0.1–4:100). The results showed that modified starches provided good thickening efficiency. Moreover, an optimum concentration of modified starches, giving the highest thickening efficiency decreased as the DS increased. Results of rheological behavior illustrated that associative networks were formed by hydrophobic interaction between octenyl side chains and acrylic particles in acrylic dispersion system. The rheological properties of modified starches prepared in this study showed a potential in using as an associative thickener in water-based coating system.     

甘薯变性淀粉的研制

总结了制取甘薯氧化淀粉、可溶性淀粉、酸变性淀粉和磷酸淀粉等变性淀粉的最佳工艺参数，并对这些变性淀粉的理化特性进行了研究。这些产品在食品、纺织、造纸、建筑、医药等行业具有广阔的应用前景。     

Ozone based food preservation: a promising green technology for enhanced food safety

Extending shelf life of food products is a major concern of the producers, and the food industry requires ‘greener’ alternatives to the current technologies. Ozone-based food preservation may suit this niche. Ozone is an attractive alternative preservative that food industry needs due to its properties such as quick decomposition and little residual effect during food preservation. Ozone is the strongest molecule available for the disinfection of water and is second only to elemental fluorine in oxidizing power. Ozone is being used in the food industry in various applications such as decontamination of water and equipment surfaces. Several researchers have focused on the application of ozone to inactivate microorganisms on fresh produce, like fruits, vegetables, meat, poultry, fish, and eggs, and dry produce, such as cereals, pulses, and spices. This review comprehensively analyses appropriate ozone concentrations and exposure times and discusses various factors that affect the quality and safety of food products during ozonation.     

Comparative analysis of desizability and retrogradation behavior of various sizing materials

The advent of high-speed shuttleless looms has increased the importance of sizing. Starch has been the most popular and economic size material. Synthetic binders are also being blended with starch to improve weaving loom efficiency. Some synthetic size materials have restrictions in use mainly because of ecological reasons. In the recent years, many modifications have come up in the starch as a sizing agent. Different modifications can give different properties, which can suit to particular application. In this study, different varieties of natural starch, modified starch, and synthetic size materials are evaluated, and properties like retrogradation and desizability were studied to investigate their potential for modern weaving conditions. Comparison is made between various materials and it is observed that paste characteristics and film properties of certain modified starches are better than the natural starch. The experiment was also designed to check the properties of blend constitution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Chemical modification of starch. II. Cyanoethylation

Rice starch was cyanoethylated by reacting it with acrylonitrile in presence of sodium hydroxide at different concentrations of acrylonitrile and various reaction temperatures. The effect of cyanoethylation on the rheological and solubility properties of starch was examined. It was found that the extent of the cyanoethylation reaction [expressed as %N and degree of substitution (DS)] increased by increasing acrylonitrile concentration provided that the latter was not less than 8 ml acrylonitrile per 10 g starch. A temperature of 50°C constituted the optimal temperature for the cyanoethylation of starch under the conditions studied. Examination of the rheological properties of the modified starch revealed that regardless of the DS, cyanoethylated starches are characterized by pseudoplastic behavior of particular interest were the results of the viscosity. Cyanoethylated starch having smaller amounts of cyanoethyl groups had higher viscosity than those of relatively larger amounts. On the other hand, the cyanoethylated starches were soluble in water regardless of the extent of cyanoethylation.     

Eco-friendly denture adhesives (EFDAs) filled with different types of natural starches: mechanical and biological performance evaluation

Abstract

This research focuses on the development of eco-friendly denture adhesives (EFDAs) by studying the effects of the addition of different types of native and modified natural starches as fillers in denture adhesive properties for dental applications. The properties of EFDAs filled with single and hybrid starches in comparison with a selected commercial denture adhesive were investigated. The investigated single starches were corn, tapioca and sago while the hybrid starches used were corn/tapioca (CT), corn/sago (CS) and tapioca/sago (TS), all with ratio of 1:1. The EFDAs were prepared with 5, 10 and 15 percent (wt. %) loading of starch filler. The starches were chemically and physically modified via oxidation and gelatinization techniques. The mechanical characterization performed were tensile bonding strength (TBS), adhesiveness and hardness, as well as cytotoxicity test by using an MTT assay for biological analysis. Mechanical analysis indicated that produced EFDAs have higher tensile bond strength, adhesiveness and hardness as compared to the commercial denture adhesive. The increment was associated with the addition of hybrid starches and an optimum filler loading at 10%. The EFDAs were also non-toxic to the dental pulp stem cells (DPSC) up to 48?h. EFDA has good potential to be used as a natural based denture adhesive as it contains natural materials namely starch which enhances its properties. The properties were suitable for better denture bonding, retention and showed good interaction with the biological environment.     

淀粉成纤加工过程中的变性方法

综述了淀粉材料的变性方法及其在改善淀粉加工性能方面的应用.同时,对淀粉纤维的发展作了较为详细的论述,指出由于淀粉可再生、可降解、成本低,淀粉纤维未来的应用前景将十分广阔.     

苄基化疏水改性淀粉的合成及水煤浆分散性能

采用氧化淀粉和羟乙基淀粉为原料,氯化苄为疏水剂,引入一定量的疏水基团苄基,制备出两种新型苄基化改性淀粉(氧化苄基化淀粉(OBS)和羟乙基苄基化淀粉(HBS))。将OBS和HBS作为分散剂应用于神华煤制备水煤浆,探讨改性淀粉对浆体的表观黏度、制浆浓度、稳定性和流变性的影响。结果表明:OBS和HBS的最佳添加量为0.50%(质量分数,下同),最大制浆浓度为65%;苄基化疏水改性后制得的淀粉分散剂均具有较好的分散效果,含苄基和羧基更多的OBS分散剂性能更佳,浆体表观黏度为842 mPa·s,7 d析水率为4.3%,煤颗粒表面Zeta电位降至-36.2 mV,体现出较好的稳定性和流变特性。OBS分散剂通过结构中的疏水基团苄基与煤中的硫水区域通过π电子极化作用力结合,形成平躺的线性折叠链式吸附。     

Structure and properties of compression-molded thermoplastic starch materials from normal and high-amylose maize starches

The structural and mechanical properties of compression-molded normal and high-amylose maize starches were studied as a function of processing water content and ageing time. Rubbery thermoplastic starches were produced by compression molding of four maize starches with differences in amylose content and amylopectin structure. Glycerol (30% on the basis of dry starch) and water (between 10 and 35% on the basis of total mass) were used as plasticizers. After processing, the amorphous thermoplastic starch materials crystallized during ageing. The semicrystalline materials contained both E-type and V-type, as well as B-type crystallinity. The properties of the thermoplastic starch materials are dependent on water content during processing, starch source, and ageing time. The normal maize starch materials are highly flexible with elongations between 56 and 104%. The elongations of the high-amylose maize starch materials were between 5–35%. The tensile stress and E-modulus of the normal maize starch materials were in the range of 3.9–6.7 and 27–131 MPa, respectively. The tensile stress and E-modulus of the high-amylose maize starch materials increased from approximately 0.5 to 23 and 5 to 700 MPa, respectively, with increasing water content during processing from 10 to 35%. The differences in mechanical properties of the normal and high-amylose materials were explained by differences in the structure of the amylose and amylopectin structure. It was concluded that both lead to differences in the starch network. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 631–644, 1997