Granular Properties of Different Starch Phosphate Monoesters

Rheological and gelling properties of atmospheric pressure cold plasma treated finger millet (Eleusine coracana) starch

Interest in exploring alternative starch sources like finger millet is rising due to wide starch applications. However, native starch often lacks desired qualities, including rheological properties. Modification is thus necessary for specific end uses. Plasma treatment as a greener and sustainable method for starch modification was therefore, studied for its ability to impact rheological properties of finger millet starch (FMS). Considerable changes in the rheological properties on FMS was noted, a significant decrease and increase (p < 0.05) in the peak viscosity (from 3.35 to 0.553 Pa.s) and paste clarity respectively was observed, indicating occurrence of depolymerization. However, intermediate plasma-treated samples (200 V) observed a decrease in paste clarity attributed to aggregate formation and cross-linking. Cross-linking was also confirmed by findings of frequency sweep where a continuous decrease in G' values of plasma treated FMS gel was interrupted by sudden increase. Despite depolymerization causing alteration of rheological behaviour such as decrease in shear thinning properties, gel strength observed a contradictory increase. This was attributed to incorporation of functional group and absence of shear responsible for network formation giving higher gel strength to FMS gels. This is elaborated in detail in the study. The study thus concluded that cold plasma significantly impacted all the rheological properties of the FMS and hence can prove to be beneficial for modification of starch rheological parameters.

Effect of ethanol, phytic acid and citric acid treatment on the physicochemical and heavy metal adsorption properties of corn starch

Corn starch dispersions were heated with ethanol (E) and reacted with phytic acid (E-PA), citric acid (E-CA), and a mixture of phytic and citric acid (E-PACA) under dry-heating to prepare heavy metal adsorbents. Microscopy images indicated that ethanol treatment induced the formation of porous structures on the surface; furthermore, treatment with phytic and citric acid induced indentations, pores, and irregular structures in E-PA, E-CA, and E-PACA starches. Phytic and citric acid were retained in the starch molecules through ester bonds with the phosphate and carboxyl groups, respectively. Starch esterification by phytic and citric acid induced a loss of crystallinity, high water absorption capacity, and low solubility. E-PACA starch exhibited more efficient Cu2+ adsorption (38.13 mg/g) than native, E, E-PA, and E-CA starches (0.11, 0.49, 2.05, and 36.23 mg/g, respectively). Thus, modification with ethanol, phytic acid and citric acid can be applied to prepare natural starch-based heavy metal adsorbents.

Effects of pin-to-plate atmospheric cold plasma for modification of pearl millet (Pennisetum glaucum) starch

The present study was done to analyze the effect of atmospheric pressure non-thermal pin-to-plate plasma at a range of different voltages (170, 200, and 230V) at different time intervals (10, 20, and 30 mins) on under-utilized pearl millet starch. The untreated and treated starches were analyzed for amylose content, pH, carbonyl, and carboxyl group, reducing sugar, turbidity, water, and oil binding property, pasting property, DSC, FTIR, XRD, and molecular weight. As cold plasma contains highly reactive species and free radicals, it is expected to cause noticeable modifications in the attributes of treated starch. There has been a significant reduction (p < 0.05) in turbidity value by 38.97% and pH value of starch from 6.49 to 4.05. Plasma-treated samples produced clearer pastes with higher stability over storage time. Cold plasma treatment also led to an increase in the ζ potential. However, there has been no significant change in the water activity and oil-binding capacity of the starch. Reducing sugar content, average molecular weight, degree of polymerization, pasting property, XRD, and FTIR data confirmed that cross-linking takes place in samples treated at lower voltages and lesser time followed by depolymerization occurring in harshly treated plasma samples. The study thus points out the possible use of cold plasma for starch modification to produce starches with altered properties.

Ultrasound application for production of nano-structured particles from esterified starches to retain potassium sorbate

Ultrasound technique was successfully used to obtain nanostructured particles from native and esterified starch, able to support the antimicrobial potassium sorbate (PS). The starch used (native, acetate or oleate) affected the nanoparticles morphology and size: globular or plate like shapes were observed for esterified and native starch respectively, while the hydrodynamic diameters were between 28 and 236 nm, with a trend towards smaller sizes for modified starches. The PS retention capacity ranged from 41.5 -90 mg/g, showing acetylated particles the highest value. The particles were amorphous and had a low average molecular weight of 1.9-6.7 × 10⁵ Da. Water retention capacity and solubility (S) were higher for modified starch particles. PS addition had minor effect, increasing S and reducing the apparent amylose content, with respect to particles without sorbate. These results demonstrated that starch modification combined with ultrasound were appropriate strategies to obtain novel and appropriate matrices to retain PS.

Cytocompatibility of a matrix of methylated cassava starch and chitosan

Starches can be used to form edible or biodegradable films, and recently modified starches have been used to form self-supporting films by casting from aqueous solution. In this work, we aimed to propose a novel starch-based composite biomaterial matrix for use in biomedical applications, especially tissue engineering. The goal of the study was to evaluate the cytocompatibility of composite hydrogels of methylated starch and chitosan, using glutaraldehyde as the cross-linker. Commercial cassava starch with high purity (96.69%) was methylated with dimethyl sulfate in order to obtain a rigid material that could possibly render stronger mechanical properties to chitosan hydrogels. Therefore, methylated starch was mixed with a solution of chitosan and the cross-linking was induced by the addition of glutaraldehyde, allowing the formation of hydrogel films which were visualized under scanning electron microscopy. The method of fabrication was optimized based on the capacity of the cells to attach to the material and proliferate. After thorough washes with ethanol and saline solution, human fibroblasts were seeded on top of the gels and allowed to grow for 3 to 5 days. Cell viability was measured using an (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MMT assay, and cell morphology was visualized by light microscopy. It was found that cells were viable at every time point, with their metabolic activity comparable to the controls (tissue culture plastic and chitosan alone), as well as clear cell–matrix interactions. Moreover, an increase in the metabolic activity over time indicated the capacity of the material to support cell proliferation. The proposed methylated starch–chitosan system is an excellent matrix that allows cell adhesion and could thereby be further assessed as a scaffold for tissue engineering.

Determination of the amylose-amylopectin ratio of starches by iodine-affinity capillary electrophoresis

This paper describes the application of capillary electrophoresis to separate and quantify the main polysaccharide components, amylose and amylopectin, present in starch samples. The separation is based on the well-known affinity of these compounds to iodine. The starch components could be effectively separated in less than 7 min using an uncoated fused-silica 'bubble cell' capillary. The proposed method has been applied for the quantitative determination of the soluble amylose content and the ratio amylose-amylopectin in commercial starches. It is shown that the present method is reliable, gives detection limits in the order of 0.1 mg mL(-1), is faster than other methodologies reported in the literature, and can be easily applied to the analysis of different starches. In spite of differences in solubility of amylopectin from different sources, a reasonable estimate of the amylose-amylopectin ratio could be made. Additionally, it was shown that the resulting profiles obtained after hydrolysis with isoamylase and alpha-amylase can provide information on the structure of the starches studied.