Cross-linked Starch Research Articles

Preparation, physicochemical properties, and in vitro digestibility of cross-linked resistant starch from pea starch

Starch in its native form may not be able to provide functional properties. Therefore, it is usually modified to make it compatible for different applications. The main aim of this research was to study the effect of cross-linking on physicochemical properties of pea starch. Therefore, starch was first cross-linked using different levels of sodium trimetaphosphate and sodium tripolyphosphate (99:1, w/w) to prepare RS4. The solubility and swelling power of RS samples decreased significantly with the increase of RS content. Cross-linked RS showed C-type XRD pattern with an increased relative crystallinity. The viscosity of RS samples decreased dramatically, and viscosity of heavily cross-linked samples dropped to around zero. The gelatinization temperatures of cross-linked starch increased, whereas melting enthalpy slightly decreased. The FT-IR spectra of cross-linked starch showed that the ratio of 1047 and 1022/cm was greater, indicating that the amount of ordered starch to amorphous starch in cross-linked starch was greater.

Effects of a Compatibilizer on the Tensile Properties of Low-Density Polyethylene/Modified Starch Blends

In this study, thermoplastic starch (TPS), cross-linked starch (CS), and cross-linked starch modified with glycerol (CTPS) were prepared, and the mechanical properties of the compatibilized low-density polyethylene (LDPE) blends (LDPE/TPS, LDPE/CS, and LDPE/CTPS) were investigated and compared with those of uncompatibilized LDPE/TPS, LDPE/CS, and LDPE/CTPS blends. Maleic-anhydride-grafted polyethylene was used as the compatibilizer. The enhanced tensile strength and elongation at break for the compatibilized LDPE/modified starch blends are a result of the improved compatibility between LDPE and the modified starch, which was confirmed by torque measurements and scanning electron microscopy.

Study on the Characterization of Cross-Linked Cassava Starch Prepared by Microwave Radiation

In this article,cassava starch was cross-linked by crosslinking agent sodium tripolyphosphate in the microwave oven. The effect of microwave time on the cross-linking degree and morphology of cross-linked starch were investigated. The results show that with the increase of microwave processing time, the degree of crosslinking of starch increases.Phosphate ester group is formed on the starch molecular chains and the structure of cross-linked starch becomes amorphous by microwave irradiation .

Functional, physicochemical properties and structure of cross-linked oxidized maize starch

Cross-linked, oxidized and cross-linked oxidized maize starches were prepared with hydrogen peroxide and sodium trimetaphosphate (STMP), respectively. The physicochemical properties, determined by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), confirmed that the native maize starch was successfully modified. The functional properties (solubility, light transmittance, retrogradation rate and freeze–thaw stability) of native and modified starches demonstrated that cross-linked starch displayed the best freeze–thaw stability. The light transmittance and retrogradation properties of cross-linked oxidized starch were highly improved compared to the native starch. This work suggested that both cross-linking and oxidation firstly happened in amorphous regions of the starch, and a possible structure of cross-linked oxidized maize starch and reaction mechanisms were hypothesized.

Selected properties of acetylated adipate of retrograded starch

Native potato starch (NS) and retrograded starch (R – obtained via freezing and defrosting of a starch paste) were used to prepare starch acetates: NS-A and R-A, and then acetylated distarch adipates: NS-ADA and R-ADA. The chemically-modified preparations produced from retrograded starch (R-A; R-ADA) were characterized by a higher degree of esterification compared to the modified preparations produced under the same conditions from native potato starch (NS-A; NS-ADA). Starch resistance to amylolysis was observed to increase (to 30–40g/100g) as a result of starch retrogradation and acetylation. Starch cross-linking had a significant impact on the increased viscosity of the paste in the entire course of pasting characteristics and on the increased values of rheological coefficients determined from the equations describing flow curves. The produced preparation of acetylated retrograded starch cross-linked with adipic acid (R-ADA) may be deemed an RS3/4 preparation to be used as a food thickening agent.

Application of quantum descriptors for predicting adsorption performance of starch and cyclodextrin adsorbents

Adsorption trend of aromatic compounds on epichlorohydrin (EPI), 1,6-hexamethylene diisocyanate (HDI), and 4,4-methylene diphenyl diisocyanate (MDI) cross-linked starch and cyclodextrin adsorbents were comparatively studied by density functional theorem (DFT) based interaction descriptors and batch adsorption studies. The DFT quantum chemical descriptors predicted adsorption trend of MDI adsorbents>HDI adsorbents>EPI adsorbents. The values of the fractional number of electrons transferred (ΔN) for all the studied adsorbent–adsorbate pair were negative, indicating that the adsorbents were electron donors in the studied adsorption interaction. The batch adsorption performance for the studied cross-linked adsorbents was in agreement with the DFT predictions. Energy gap, chemical hardness, and softness showed good linear correlation (R2=0.8073±0.2259) to the batch adsorption performance for most of the studied adsorbent–adsorbate pairs. The present study demonstrated that DFT quantum chemical parameters are suitable adsorption descriptors for predicting adsorption performance of cross-linked adsorbents.

Comparative Study of the Physicochemical, Drug Loading and Releasing Properties of Cross-linked Cassava, Enset and Potato Starches

Cassava, enset and potato starches were modified by cross-linking in solid phase system, using sodium hexametaphosphate (SHMP) as cross-linking agent, under different microwave powers (90, 220 and 350 W) and reaction times ranging from 1 to 6 min to investigate and compare their physicochemical, drug loading and release properties. The swelling power, water holding capacity, paste clarity, degree of cross-linking (DC) and peak viscosity of the starches varied with starch sources as well as between the cross-linked starches and their native counterparts. Studies on drug loading capacity and encapsulation efficiency showed that cross-linked enset starch loaded higher amount of drug in 0.1 N HCl, 0.9% NaCl and pH 7.4 phosphate buffered saline (PBS) media as compared to cross-linked cassava and potato starches. After 12 h, cross-linked enset starch matrix released about 90% of the model drug, paracetamol, indicating their ability to sustain drug release and their potential to be used as drug-release-sustaining pharmaceutical excipient.Keywords: cassava starch, enset starch, potato starch, degree of cross-linking, drug release

Structural and physical properties of granule stabilized starch obtained by branching enzyme treatment

Chemical cross-linking of starch is an important modification used in the industry for granule stabilization. It has been demonstrated that treatment with branching enzyme (BE) can stabilize the granular structure of starch and such treatment thereby provides a potential clean alternative for chemical modification. This study demonstrates that such BE-assisted stabilization of starch granules led to partial protection from BE catalysis of both amylose (AM) and amylopectin (AP) in their native state as assessed by triiodide complexation, X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The granule stabilizing effects were inversely linked to hydration of the starch granules, which was increased by the presence of starch-phosphate esters and suppressed by extreme substrate concentration. The data support that the granule stabilization is due to the intermolecular transglycosylation occurring in the initial stages of the reaction prior to AM–AP phase separation. The enzyme activity needed to obtain granule stabilization was therefore dependent on the hydration capability of the starch used.

Preparation and Thermodynamics Adsorption Performance of Cobalt Ions on the Crosslinked Starch Microspheres

A type of cross-linking starch microspheres (CSMs) has been synthesized by reversed phase suspension method using soluble starch as raw material. Crosslinked starch microsphere has good adsorption performance to metal ions in water. The static adsorption behaviors of Co2+on the cross-linked starch microspheresand were investigated. The CSMs and its adsorption product were comparatively characterized by Fourier Transform Infrared Spectroscopy (FTIR). The adsorption behaviour of CSMs in different temperatures is in agreement with the Freundlich isothermal equation and isothermal equation of Langmiur. The thermodynamic parameters of adsorption process indicate that entropy is the main adsorption driving force, and physical adsorption is main about the adsorption behaviors of CSMs on Co2+.These data are helpful for the adsorption separation of metal ions and the treatment of the wastewater containing Co2+. Keywords: cross-linked starch microspheres;cobalt ions;adsorption mechanism;thermodynamics adsorption

The effect of pH on hydrolysis, cross-linking and barrier properties of starch barriers containing citric acid

Citric acid cross-linking of starch for e.g. food packaging applications has been intensely studied during the last decade as a method of producing water-insensitive renewable barrier coatings. We managed to improve a starch formulation containing citric acid as cross-linking agent for industrial paper coating applications by adjusting the pH of the starch solution. The described starch formulations exhibited both cross-linking of starch by citric acid as well as satisfactory barrier properties, e.g. fairly low OTR values at 50% RH that are comparable with EVOH. Furthermore, it has been shown that barrier properties of coated papers with different solution pH were correlated to molecular changes in starch showing both hydrolysis and cross-linking of starch molecules in the presence of citric acid. Hydrolysis was shown to be almost completely hindered at solution pH≥4 at curing temperatures≤105°C and at pH≥5 at curing temperatures≤150°C, whereas cross-linking still occurred to some extent at pH≤6.5 and drying temperatures as low as 70°C. Coated papers showed a minimum in water vapor transmission rate at pH 4 of the starch coating solution, corresponding to the point where hydrolysis was effectively hindered but where a significant degree of cross-linking still occurred.

Effects of cross-linked resistant rice starch on the quality of Korean traditional rice cake

Jeolpyeon, the Korean traditional rice cake, was prepared from the newly developed dry rice flour with 10 and 20% cross-linked resistant starch (RS4) to improve sanitation during processing and to enrich the functional properties of dietary fiber. The rice flour was prepared from white rice ‘Chuchungbyeo’ through soaking, drying and milling using a pin mill with a built-in 120 mesh sieve. The total dietary fiber contents were 44.97% for RS4, 3.57% for rice cake, 7.78 and 11.35% for 10 and 20% RS4 added jeolpyeon, respectively. With an increase in RS4 content, the swelling power, solubility, water binding capacity, and all pasting viscosities decreased, while lightness increased. Cohesiveness and resilience in the 10% RS4 added jeolpyeon was higher than those in the control. The preference test showed that the color and overall quality increased with the addition of RS4 and overall quality was the highest in the 10% RS4 added jeolpyeon.

Effect of Pyrodextrinization, Crosslinking and Heat- Moisture Treatment on In vitro Formation and Digestibility of Resistant Starch from African Locust Bean (<i>Parkia biglobosa</i>)

Purpose: This investigation was carried out to determine the impact of Parkia biglobosa starch modification on the fractions, namely rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS). Methods: Aqueous solution of sodium hypochlorite and potassium hydroxide was used to extract starch prior to modification by pyrodextrinization, cross-linking and heat-moisture treatment. Solubility, swelling power, x-ray diffraction, scanning electron microscopy (SEM) and thermal properties of the native and modified starches were also studied. Results: Pyrodextrinization (PD), cross-linking (CL), and heat-moisture treatment (HMT) reduced the swelling power to 6.73, 4.17 and 5.57 g/g, respectively but increased solubility by 59.0, 41, 41.5 and 39.5 %, respectively, and tended to decrease gelatinization enthalpy (ΔH). Starch yield was 25.7 % on a whole seed basis. RS content significantly (p < 0.05) increased to 46.3, 49.2 and 45.3 %, respectively following PD, CL and HMT. X-ray diffraction resulrs indicate the presence of V-type crystallinity in the modified parkia starch while SEM showed PD and CL starch structures were more compact and dense than HMT starch which was irregularly-shaped formed. Conclusion: Native parkia starch modified by pyrodextrinization, cross-linking and heat-moisture treatment showed appreciably higher thermal stability which makes it suitable for incorporation in foods that are subject to high temperature processing and high shear.

Molecular structure of citric acid cross-linked starch films

The effect of citric acid (CA) on starch films has been examined. A new method to detect cross-linking of starch by CA in solution-cast films by molecular weight measurements is described. Furthermore, we managed to distinguished between free, mono- and di-esterified CA and quantify di-ester content within starch films by using a modification in the method of complexometric titration with copper(II)-sulfate. Cross-linking of starch by CA occurred at low temperature, 70°C, which we assumed is so far the lowest temperature reported where cross-linking reaction occurred. This is essential for starch coating applications within paper industry since no high temperatures for curing will be required. However, curing at 150°C and high CA concentrations, 30pph, increased cross-linking reaction. Furthermore, the physical properties like water solubility, gel content and glass transition temperature, were highly reflected by changes in the molecular structure i.e. cross-linking and hydrolysis, as well as CA content and curing temperature.

Investigation of magnetically enhanced swelling behaviour of superparamagnetic starch nanoparticles

The present study follows a novel strategy for the preparation of superparamagnetic nanoparticles of cross-linked starch impregnated homogeneously with nanosized iron oxide. The prepared magnetic nanoparticles were characterized by infra-red (FTIR) spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction and magnetization studies. The size of the magnetic polymeric particles was found to lie in the range of 20–80 nm, and they exhibited superparamagnetic properties. The particles were allowed to swell in phosphate buffer saline (PBS) and the influence of factors such as chemical composition of nanoparticles, pH and temperature of the swelling bath and applied magnetic field was investigated on the water intake capacity of the nanoparticles. The prepared nanoparticles showed potential to provide a possible option for controlled and targeted delivery of anticancer drugs, applying external magnetic field.

Formulation development and evaluation of lamivudine controlled release tablets using cross-linked sago starch

Objectives: Modified starches based polymeric substances find utmost applicability in pharmaceutical formulation development. Cross-linked starches showed very promising results in drug delivery application. The present investigation concerns with the development of controlled release tablets of lamivudine using cross-linked sago starch.Methods: The cross-linked derivative was synthesized with phosphorous oxychloride and native sago starch in basic pH medium. The cross-linked sago starch was tested for acute toxicity and drug-excipient compatibility study. The formulated tablets were evaluated for various physical characteristics, in vitro dissolution release study and in vivo pharmacokinetic study in rabbit model.Results: In vitro release study showed that the optimized formulation exhibited highest correlation (R) in case of zero order kinetic model and the release mechanism followed a combination of diffusion and erosion process. There was a significant difference in the pharmacokinetic parameters (Tmax, Cmax, AUC, Vd, T1/2, and MDT) of the optimized formulation as compared to the marketed conventional tablet Lamivir®.Conclusion: The cross-linked starch showed promising results in terms of controlling the release behavior of the active drug from the matrix. The hydrophilic matrix synthesized by cross-linking could be used with a variety of active pharmaceutical ingredients for making their controlled/sustained release formulations.

The effects of the addition of corn husk fibre, kaolin and beeswax on cross-linked corn starch foam

Significant efforts have recently been made to improve the physical properties of starch foams formed using baking processes. For example, cross-linking starch with 0.126g/kg glyoxal considerably reduces the baking time, density and water absorption of starch foams. In this study, we attempted to further develop the physical properties of glyoxal cross-linked starch foam by adding corn husk fibre, kaolin, beeswax and combinations of these products. We also studied the effects of these components on the microstructure and physicochemical and mechanical properties of trays. Starch-based trays in which additives were used showed improved water resistance. The water absorption capacities of the trays were 13%, 14% and 9% when combinations of kaolin/beeswax, fibre/beeswax and fibre/kaolin/beeswax were added, respectively.We found that baked foams formulated with only cross-linked starch had higher tensile and flexural strength than composite foams of either cross-linked starch/kaolin or cross-linked starch/beeswax. However, using combinations of additives further increased the tensile and flexural strength of baked foams, with the exception of cross-linked starch/beeswax/kaolin composite foams. Furthermore, all mechanical properties of the trays were superior to those produced using only cross-linked starch.

The effects of cross-linked starch on the properties of thermoplastic starch

In order to improve the poor tensile properties and high water absorption of thermoplastic starch (TPS), cross-linked starch was added into the TPS matrix. The cross-linked starch contents ranged from 0wt% to 20wt%. The TPS/cross-linked starch composites were analyzed for the morphology of their fractured surfaces, the thermal decomposition temperatures, ability to absorb water and mechanical properties. The results showed that the incorporation of cross-linked starch into the TPS matrix caused considerable improvement to tensile strength. The maximum tensile strength was obtained with addition of 20wt% cross-linked starch. Moreover, water absorption of the TPS samples was clearly reduced by the inclusion of cross-linked starch. The thermal degradation temperatures of the composites were also higher than those of the TPS matrix.

Synthesis of cross-linked starch based polymers for sorption of organic pollutants from aqueous solutions

Three cross-linked starch based polymers (1–3) were prepared by reaction between starch and hexamethylene diisocynate in the presence of dimethylformamide. The cross-linked adsorbents were used for the recovery of 4-nitrophenol (pNP) and 4-chlorophenol (pCIP) from aqueous solutions. Characterization of the polymers was performed by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy thermogravimetric analysis (TG) and differential thermal analysis (DTA). It was observed that the X-ray diffraction patterns of native starch and cross-linked starch were similar. TG-DTA studies revealed that the decomposition temperature of cross-linked starch was higher than that of native starch. The influence of pH, adsorbent dose and contact time on the percentage sorption capacity was examined using batch study. Adsorption results revealed that the starch-based bio-adsorbents showed high sorption capacity towards pNP and pCIP. At optimized conditions the maximum sorption capacity observed for polymer 3 was 83% for pNP. Substitution of experimental data values in the Freundlich model showed favourable results as compared with the Langmuir model.

Effects of cross-linked tapioca starches on batter viscosity and oil absorption in deep-fried breaded chicken strips

In this study, the effectiveness and feasibility of using various degrees of cross-linked tapioca starches in batter and breading formulations to reduce oil absorptions in deep fried chickens were investigated. Shear flow behaviour, water retention capacity (WRC), pick-up as well as cooked yield of the prepared batters were also examined. Flow curves showed that all studied batters were pseudoplastic, i.e. having shear thinning characteristics. In addition, it was found that the substitution of 20% (w/w) cross-linked starches for wheat flour in the batter formulation significantly reduced the consistency index and WRC of the batters. However, batter pick-up and cooked yield values were insignificantly affected. Oil uptake of fried chicken crusts was determined using differential scanning calorimetry due to its specific advantages over the conventional solvent extraction method. In comparison to the control (wheat) formulation, crusts of fried chicken samples obtained from the formulations containing 20% (w/w) cross-linked starch showed significantly lower oil content by at least 17% relative oil reduction. The highest relative oil reduction was found in the batter containing the highly cross-linked tapioca starch. Furthermore, an increase in water content in the batter formulations resulted in a reduction in the batter pick-up, cooked yield and oil absorption. The degree of cross-linking which in turn resulted in the limited starch granule disintegration is the predominant factor in the reduction of oil content for deep-fried battered food.

Preparation, stability and antimicrobial activity of cationic cross-linked starch–iodine complexes

Cationic cross-linked starch (CCS)–iodine complexes containing different amounts of quaternary ammonium groups (different degrees of substitution (DS)) and iodine have been obtained by iodine adsorption on CCS from aqueous iodine potassium iodide solution. Equilibrium adsorption studies showed that with an increase of DS the amount of iodine adsorbed on CCS and the affinity of iodine to CCS increased linearly.The influences of the DS of CCS and the amount of adsorbed iodine on the stability of CCS–iodine complexes in a solution of 0.02M sodium acetate and reactivity toward l-tyrosine have been investigated. At the same DS, the stability of CCS–iodine complexes decreased with an increase of the amount of adsorbed iodine. With increasing the DS, the stability of CCS–iodine complexes increased. The iodine consumption in the reaction with l-tyrosine increased significantly with an increase of the amount of adsorbed iodine. The influence of DS on iodine consumption was lower and depended on the amount of adsorbed iodine. The antibacterial activity of CCS–iodine complexes against Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli was determined by the broth-dilution and spread-plate methods. The obtained results have demonstrated that an appropriate selection of the CCS–iodine complex composition (the DS of CCS and the amount of adsorbed iodine) could ensure good antimicrobial properties by keeping a low concentration of free iodine in the system. The main advantage of using CCS–iodine complexes as antimicrobial agents is the biodegradability of the polymeric matrix.