Structure, morphology and functionality of acetylated and oxidised barley starches

Abstract

Acetylation and oxidation are chemical modifications which alter the properties of starch. The degree of modification of acetylated and oxidized starches is dependent on the catalyst and active chlorine concentrations, respectively. The objective of this study was to evaluate the effect of acetylation and oxidation on the structural, morphological, physical-chemical, thermal and pasting properties of barley starch. Barley starches were acetylated at different catalyst levels (11%, 17%, and 23% of NaOH solution) and oxidized at different sodium hypochlorite concentrations (1.0%, 1.5%, and 2.0% of active chlorine). Fourier-transformed infrared spectroscopy (FTIR), X-ray diffractograms, thermal, morphological, and pasting properties, swelling power and solubility of starches were evaluated. The degree of substitution (DS) of the acetylated starches increased with the rise in catalyst concentration. The percentage of carbonyl (CO) and carboxyl (COOH) groups in oxidized starches also increased with the rise of active chlorine level. The presence of hydrophobic acetyl groups, carbonyl and carboxyl groups caused a partial disorganization and depolymerization of starch granules. The structural, morphological and functional changes in acetylated and oxidized starches varied according to reaction conditions. Acetylation makes barley starch more hydrophobic by the insertion of acetyl groups. Also the oxidation promotes low retrogradation and viscosity. All these characteristics are important for biodegradable film production.

Morphological, mechanical, barrier and properties of films based on acetylated starch and cellulose from barley

“…While comparing the starch films without the addition of cellulose fibers, it was observed that the acetylated starch film showed a lower percentage of residues at 200 and 400 °C (Table ), showing that this film had less thermal stability than the native starch film. This could be attributed to the depolymerization of the starch chains during acetylation . In addition, the presence of fibers in polymeric matrix increased the thermal stability of the starch films.…”

“…Research efforts in the area of polymeric materials have focused on the development of biodegradable materials obtained from renewable resources . Among these materials the starches that are the most abundant and the cheapest materials that come from renewable resources stand out.…”

“…However, there are no reports on films developed from acetylated barley starches. A previous study was conducted by our group to characterize the acetylated barley starches. This acetylated starch was used to produce the films for this study; and cellulose fibers obtained from barley husk were used as the reinforcement in starch films, in order to improve the mechanical properties and water barrier of the films.…”

Physical Properties, Microstructure, Intermolecular Forces, and Oxidation Stability of Soybean Oil Oleogels Structured by Different Cellulose Ethers

“…The XRD pattern of the pure HPMC powder (seen from [25] ) presented two diffraction peaks at around 8.6 and 20.1 , and the pure MC powder showed two diffraction peaks at around 9.0 and 20.0 , respectively. Relative crystallinity of the oleogel samples calculated by Jade 6.0 were approximately 40% according to the methods reported by El Halal et al [36] and Park et al [37] Relative crystallinity was calculated by Equation (2): [34,35] The pattern of XG powder (seen from [25] ) presented a broad peak at around 20.0 .…”

Induced effects by oxidation with potassium permanganate on the thermal, morphological, colorimetric and pasting properties of corn starch

“…During the oxidation process, the hydroxyl groups present at C-1, C-2 and C-3 of the starch molecules are initially oxidised to carbonyl groups and then to carboxyl groups, which indicate the degree of oxidation. Parallel to this, there is the breaking of glycoside bonds with partial depolymerisation of starch [5].…”