Acetylated Corn Starch Research Articles

Acetylation of banana (Musa paradisiaca L.) and corn (Zea mays L.) starches using a microwave heating procedure and iodine as catalyst: II. Rheological and structural studies

The effect of iodine concentration on the acetylation of starches with low and moderate degree of substitution (DS<0.5) and its impact on the physicochemical feature and structural features was evaluated. The acetylated starches were prepared with 0.03mol anhydroglucose unit, 0.12mol of anhydride acetic, and 0.6, 0.9 or 1.4mM of molecular iodine as catalyst in a sealed Teflon vessel using microwave heating (600W/2min). Pasting profile and rheological properties were obtained under steady flow; dynamic oscillatory test was used. Structural features were obtained by HPSEC-RI. In acetylated starches, DS and acetyl groups increased when the iodine concentration increased, corn starch showed higher values than banana starch. The viscosity of acetylated starches decreased relative to unmodified starches while, acetylated corn starch had lower value than acetylated banana starch. In the flow curves, a non-Newtonian pattern (shear-thinning) was shown in the pastes of native and modified starches. Storage modulus (G’) and loss modulus (G”) showed low dependence on frequency (G’αω0.1; G”αω0.2) on frequency sweep test, which is characteristic of a viscoelastic gel. Debranched native banana and corn starches presented trimodal chain-length distribution. The pattern was maintained in the acetylated starches, but with different level of short and long chains. The structural differences in native and acetylated samples explain the rheological characteristics in both starches.

Optimization of Processing Technology of Acetylated Corn Starch Films

Abstract. In this experiment acetylated corn starch was taken as the raw material and its filming property was studied through single-factor experiments and orthogonal experiment. The results showed that the different concentrations of acetylated corn starch, glycerol, polyvinyl alcohol (PVA) and glutaraldehyde had significant effects on the properties of the acetylated corn starch/PVA films. And the optimum film-forming conditions were 4.5% acetylated corn starch, 4.5% PVA, 4.0% glycerol and 0.4% glutaraldehyde for the coating liquid of film-forming, among which the most important factor was the glycerol concentration; the following factors were the acetylated corn starch concentration, the polyvinyl alcohol concentration and the glutaraldehyde concentration.

Properties and antimicrobial activities of starch–sodium alginate composite films incorporated with sodium dehydroacetate or rosemary extract

AbstractAntimicrobial films were prepared with oxidized and acetylated corn starch–sodium alginate by incorporating sodium dehydroacetate or rosemary extract. Films incorporated with sodium dehydroacetate ≥ 0.1% or rosemary extract ≥ 0.3% had an anti‐Escherichia coli effect. Aspergillus niger could be effectively inhibited by the incorporation of sodium dehydroacetate ≥ 0.3%. Rosemary extract showed no inhibitory effect on Aspergillus niger. Sodium dehydroacetate and rosemary extract reduced the tensile strength and elongation at break, and increased the water vapor permeability of the films. Sodium dehydroacetate made the films more greenish–yellow with the increase of sodium dehydroacetate concentration. The color of the films became darker and more reddish–yellow as rosemary extract was increased. Fourier transform infrared (FTIR) spectra analysis revealed that sodium dehydroacetate and rosemary extract reduced starch crystallinity. The surface of the films became rougher as a result of an addition of sodium dehydroacetate and rosemary extract. These findings had potential applications in prolonging food shelf life based on different needs. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis, characterization and functional properties of low substituted acetylated corn starch

Acetylated corn starch (ACS) was synthesized by the reaction of native corn starch (NCS) with acetic anhydride (AA) in an aqueous medium in the presence of sodium hydroxide as a catalyst. The factors that could affect the degree of substitution (DS) and reaction efficiency (RE) of corn starch were investigated which included the reaction temperature and time, the mass ratio of AA to starch, the ratio of the water volume to starch mass and pH. The optimal DS of 0.071 and RE of 67.05% was obtained. FTIR spectrometry showed new bands at 1733, 1375 and 1252cm−1. The SEM of the ACS indicated some cavities on the granules which fused together, compared with NCS. Wide angle X-ray diffraction revealed that ACS had a similar profile as NCS (A type). However, the intensity of peaks were diminished. DSC thermograms exhibited that ACS had some lower gelatinization temperatures and enthalpies than NCS. The functional properties of ACS such as the swelling power, solubility, water absorption, clarity, freeze-thaw stability, retrogradation and viscosity were also studied. The results suggest that the ACS has much better functional properties than the NCS, and could be expected to have wide applications especially in food industry.

Preparation and Characterisation of Acetylated Corn Starches

Preparation and Characterisation of Acetylated Corn Starches

Biodegradable packages development from starch based heat sealable films

Heat sealing capacity of native and acetylated corn starch based films was evaluated to develop biodegradable packages, such as bags. Thermo-mechanical properties were analyzed since they condition their handling and applications. Acetylated starch addition reinforced 80% sealing resistance of starch films. Unplasticized heat-sealed films presented adhesive failures while those containing glycerol showed a rupture near the zip. Unplasticized films exhibited a single relaxation (at around 60 °C), detected by DMA and conventional DSC, which was not affected by the acetylated starch content. DMA curves of plasticized films showed two relaxations, one close to −50 °C associated to the glass transition of the plasticizer-rich phase, and other around 60 °C, attributed to the starch-rich phase. This last transition was also observed using MTDSC. Glycerol addition decreased the relaxation temperature of the starch-rich phase being this effect more marked in native starch films, about 28%. A relation between film composition, microstructure, mechanical behavior, and dynamic mechanical thermal analysis was established.

Characterization of Acetylated Corn Starch Prepared under Ultrahigh Pressure (UHP)

To investigate the impact of ultrahigh pressure (UHP) on the physicochemical properties of the UHP-assisted starch acetate, common corn starch was subjected to either conventional (0.1 MPa, 30 degrees C, 60 min) or UHP-assisted (400 MPa, 25 degrees C, 15 min) acetylation reactions at three levels (4, 8, or 12%) of acetic anhydride. Without significant changes in starch granule crystal structure, UHP-assisted reaction exhibited lower degree of substitution values than conventional reaction across reagent addition levels. An increase in reagent addition levels exhibited common trends in starch solubility/swelling power, gelatinization, and pasting properties for the conventional and UHP-assisted starch acetates relative to native starch. Within an equivalent derivatization level, however, the UHP-assisted (relative to conventional) starch acetates revealed restricted starch solubility/swelling power, reduced gelatinization temperatures, and lower pasting viscosities. Overall, this result suggested that UHP treatment in acetylation reaction might influence the physicochemical properties of starch acetate by facilitating the formation of lipid-complexed amylose or altering granular reaction patterns to acetic anhydride.

Ultra high pressure (UHP)-assisted acetylation of corn starch

Potential roles of ultra high pressure (UHP) in starch granule reactivity and properties of acetylated starch were investigated. Corn starch was substituted with acetic anhydride at pressure range of 0.1–400 MPa for 15 min; also, conventional reaction (30 °C, 60 min) was conducted as reaction control. Native and acetylated corn starches were assessed with respect to degree of substitution (DS), X-ray diffraction pattern/relative crystallinity, starch solubility/swelling power, gelatinization, and pasting behavior. For the UHP-assisted acetylated starches, DS values increased along with increasing pressure levels from 200 to 400 MPa, and reaction at 400 MPa exhibited maximum reactivity (though lower than the DS value of the reaction control). Both UHP-assisted and conventional acetylation of starch likely occurred predominantly at amorphous regions within granules. Gelatinization and pasting properties of the UHP-assisted acetylated starches may be less influenced by UHP treatment in acetylation reaction, though restricted starch solubility/swelling were observed.

Effect of acetylation on the properties of corn starch

Acetylated corn starches with different degrees of substitution (DS 0.85, DS 1.78, DS 2.89) were synthesized by the reaction of corn starch with acetic anhydride in the presence of acetic acid under varying reaction temperatures. The product was characterized by FTIR spectroscopy, 1H NMR, X-ray diffraction and contact angle measurement. Acid-base titration and 1H NMR methods were employed to determine the degree of substitution of product. FTIR spectroscopic analysis showed that the characteristic absorption intensities of esterified starch increased with increase in the degree of substitution, and the characterized peak of hydroxyl group almost disappeared in the spectrum of DS 2.89 acetylated starch. The detailed chemical microstructure of native starch and acetylated starch was confirmed by 1H NMR, 13C NMR and 13C– 1H COSY spectra. Analysis of 1H NMR spectra of acetylated starches was assigned accurately. Strong peaks in X-ray diffraction of acetylated starch revealed that new crystalline regions were formed. Compared with native starch, the hydrophobic performance of acetylated starch esters was increased. The contact angle of acetylated starch with DS 2.89 was 68.2°.

Selected Morphological and Functional Properties of Extruded Acetylated Starch−Polylactic Acid Foams

Native starch and polylactic acid (PLA) are biodegradable polymers that can be used in packaging materials. Their hydrophilic properties hinder their widespread use. Hydrophobicity can be improved significantly by acetylating native starch. This study was conducted to determine the morphological and functional properties of acetylated starch−PLA foams. Acetylated corn starch, with a degree of substitution (DS) of 2.3, and acetylated potato starch, with a DS of 1.07, were extruded with 5, 10, or 15% PLA in a twin screw co-rotating extruder at 150, 160, or 170 °C barrel temperatures and 130, 150, or 170 rpm screw speeds. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to analyze the morphological properties of the extruded foams. A central composite response surface design was used to analyze the effects of acetylated starch type, PLA content, barrel temperature, and screw speed on the specific mechanical energy requirements of preparing extruded foams and the radial expansion ratios and compressibilities of the extruded foams. DSC showed that glass transition temperatures (Tg's) and melting temperatures (Tm's) of DS 2.3 corn starch−PLA foams were between the Tg's and Tm's of DS 2.3 corn starch and PLA. The Tg's of DS 1.07 potato starch−PLA foams were higher than those of acetylated potato starch and PLA, while the Tm's were closer to that of the PLA, when acetylated potato starch was the predominant phase in the blends. XRD showed that both acetylated starch and PLA lost crystallinity during extrusion. The X-ray pattern of the DS 1.07 potato starch−PLA foam was similar to those of DS 1.07 potato starch and PLA. FTIR spectroscopy confirmed no new bonds were formed in either DS 2.3 corn starch−PLA or DS 1.07 potato starch acetate−PLA foams. The type of acetylated starch, PLA content, barrel temperature, and screw speed had significant effects on the specific mechanical energy requirements, radial expansion ratios, and compressibilities of the acetylated starch foams.