Structure Of Native Starch Research Articles

Preparation and Characteristics of Starch‐Based Pickering Emulsions: Effects of Rosin Acid and Starch Size

AbstractThis study aims to research the effects of rosin acid (RA) and size of starch on the properties of Pickering emulsifier. Potato (PS, 10–100 µm), corn (CS, 5–25 µm), and rice (RS, 3–8 µm) starches are modified with RA, and their starch ester is used to prepare Pickering emulsions. The results of scanning electron microscopy, X‐ray diffraction, and nuclear magnetic resonance hydrogen spectrum analysis reveal that the structure of native starch is largely destroyed, and esterification occurs between starch and RA. The starch‐based Pickering emulsion, which is esterified by RA, has the uniform particle size and higher stability than native starch. With prolonged storage, the emulsion of large‐sized RA–starch (PS and CS) show a stable gel phenomenon, and the emulsion of small‐sized RA–starch (RS) is a Newton fluid. In addition, the results indicate that RA–starch displays high viscosity and emulsifying properties.

Effects on the structure and properties of native corn starch modified by enzymatic debranching (ED), microwave assisted esterification with citric acid (MCAE) and by the dual ED/MCAE treatment

Native corn starch was modified by enzymatic debranching (ED), microwave assisted citric acid esterification (MCAE), and by dual ED/MCAE. The structure and properties of native starch (NS), and the resulting debranched starch (DS), microwave assisted citric acid esterified starch (MCS), and microwave assisted citric acid debranched starch (MCDS) were determined and compared. Both the morphology and crystalline regions of the modified starches were changed by ED and MCAE. ED increased significantly the amylose content and transparency, but decreased the in vitro enzymatic digestibility, freeze thaw stability and relative crystallinity of DS compared to those of NS. MCAE produced a decrease in amylose content, transparency, in vitro enzymatic digestibility, and relative crystallinity, but increased the freeze-thaw stability of MCS compared to NS, and of MCDS compared to DS. The A-type crystalline structure of NS and DS was changed to B-type crystalline structure after MCAE treatment, and a new FTIR characteristic band at 1735 cm−1 was observed for MCS and MCDS. This work provides insights for producing esterified corn starches by a combined enzyme, microwave and organic acid novel technology.

Effects of Agrobacterial<i> rol</i>-Genes on the Thermodynamic and Structural Features of Starches Extracted from Potato Microtubers

Wild-type potato (Solanum tuberosum L.) plants and their transformants harboring agrobacterial rolB or rolC genes under control of the patatin class I promoter were cultured in vitro. These plants were used as a source of single-node stem cuttings. The structure of native starch in tubers formed on cuttings was determined using methods of X-ray scattering and differential scanning microcalorimetry (DSC). It was found that in starch from tubers of rolB plants the melting temperature of crystalline lamella was lower and their thickness was less than that in wild-type potato. In tubers of rolC plants starch differed from starch in wild-type plants by a higher melting temperature, reduced melting enthalpy, and a greater thickness of crystalline lamellae. The melting of starch from tubers of rolC plants proceeded as the melting of two independent crystalline structures with melting temperatures of 338.0°K and 342.8°K. Overall data show that starches of different structure can be obtained by using transgenic approach.

The influence of O-formylation on the scale of starch macromolecules association in DMSO and water

There is a great challenge in finding treatments that may degrade the initial grain structure of native starch in order to get better mixing properties of the resulting degradation product with other polymers. Among the possible treatments, O-formylation has already been proposed but only little structural information on the resulting degradation products is available, certainly due to its heterogeneity. The present study aims to complement our knowledge on the structure of macromolecules following the chemical reaction by means of different techniques. At first, polarimetry reveals, on amylose and maltodextrin samples, that the helix content remains unchanged after esterification. Then, high resolution 1H NMR measurements allow to determine the association parameter, p, and it was found that the fraction of associated helix, although strongly influenced by the nature of the solvent, is similar for native and starch formate. It was deduced that formic acid is not reactive on the less accessible macromolecules such as the aggregates preserved from the initial destructuration of starch during gelanitisation and following the thermal treatment, i.e. the larger molar weight samples. Finally, AFM observation corresponded well with the results obtained by the other techniques, since large aggregates, such as helix assemblies or amorphous and globular aggregates, were found to be unaffected by the formic acid treatment.

A small-angle X-ray scattering study of the annealing and gelatinization of starch

The structure of starch in its native state and during gelatinization was studied using small-angle X-ray scattering (SAXS). The scattering data were then modelled by considering the theoretical scattering from a finite number of infinite lamellar planes of crystalline and amorphous material, embedded in a medium of specified electron density. The changes in the SAXS pattern during gelatinization could be modelled simply by changing the relative electron densities of the system, thereby observing directly the absorption of water and the disruption of crystallinity. This rigorous analysis of the SAXS data from starch has provided new insights into the structure of native starch and the mechanisms of gelatinization.

On the Structure of Native Starch — An Analogue to the Quartz Structure

AbstractThe branching geometry of amylopectin according to chemical degradation studies has been combined with the knowledge of packing arrangement of double helices. The structural organization of the polyglucan chains in the crystalline amylopectin units can be described by an infinite periodic minimal surface, and it is closely related to the structure of high‐quartz with space group P6422. An important feature of the molecular packing is that the van der Waals distance between double helices is very similar to the length of a linkage formed by the α‐1,6‐glucoside branching. The physical properties of starch are finally discussed in relation to the proposed structure.