Gaseous Ozonation of Pigeon Pea, Lima Bean, and Jack Bean Starches: Functional, Thermal, and Molecular Properties

Use of ozone oxidation in combination with deacetylation for improving the structure and gelation properties of konjac glucomannan

In this study, oxidized deacetylated konjac glucomannans with different degrees of oxidation were prepared by a combination of deacetylation and ozone oxidation. Carboxyl groups were found to be introduced into the modified konjac glucomannan while acetyl groups were removed. The backbone, branched chains, and crystal structure of modified konjac glucomannan were not significantly affected. The whiteness was enhanced to 97-99 % and the thermal degradation temperature was up to 250 °C after modification. The solubility of the modified konjac glucomannan (oxidized for 60 min) was significantly increased to 84.56 % (p < 0.05), while its viscosity and swelling power were notably decreased owing to the changes in molecular weight (from 106 to 104) and functional groups. Rheological analysis showed that oxidized deacetylated konjac glucomannan has the ability to form soft-textured gels and the potential to develop dysphagia foods. Future studies should focus on the gelation mechanisms of oxidized deacetylated konjac glucomannan.

Molecular morphology & interactions, functional properties, rheology and in vitro digestibility of ultrasonically modified pearl millet and sorghum starches

The present research investigated to study the effect of ultrasound treatment on isolated pearl millet starch (PMS) and sorghum starch (SS). Ultrasonication was applied to PMS and SS for 10, 15, and 20 min. Ultrasonically modified pearl millet and sorghum starches evaluated for their techno-functionality, pasting profile, morphology, in vitro starch digestibility, XRD, and molecular interactions. Ultrasound treatment increased water and oil absorption capacity, swelling power, and solubility with treatment time. For ultrasonicated PMS and SS, a significant increase (p < 0.05) in paste clarity (PC) (70.05 % and 67.23 %), freeze-thawing stability (FTS), gel consistency (GC) (25.05 mm and 32.95 mm), and in vitro starch digestibility were observed (57.70 g/100 g and 50.29 g/100 g), whereas no significant changes were recorded for the color values after the ultrasound treatment. Variations in pasting property were also observed in ultrasonicated starches with treatment duration. SEM images confirmed ultrasonication mainly forms pores and indentations on starch granule surface. FTIR spectra and X-ray diffractogram for ultrasonicated starches revealed a slight decrease in the peak intensity and A-type X-ray pattern with lower relative crystallinity (RC) than the native starches. G' > G″ value, indicating the elastic behavior and lower tan δ value, depicting viscous behavior and high gel strength.

Physicochemical Properties of Wild Yam (Dioscorea villosa) Starch

Native starch extracted from wild yam (Dioscorea villosa) was evaluated for its intrinsic physicochemical properties. From the results, essential metals such as K, Ca, P, and Fe were detected along with some nonessential heavy metals below the WHO permissible limits. Bulk density was 0.13-0.63 g/mL. The water absorption capacity, oil absorption capacity, swelling power, and solubility of the starch were pH-responsive. Thermal profiles showed onset temperature, To (59.21 °C), peak temperature, Tp (60.22 °C), endset temperature, Tc (63.12 °C), gelatinization enthalpy, ΔHgel (0.54 J/g), temperature range of gelatinization, R (3.91 °C), and peak height index, PHI (1.87 J/g °C). Exhibiting a crystallite size of 0.03 nm, absorption peaks of 15.3119°, 24.4120°, and 18.4170°, corresponding to interplanar d-spacings of 3.7500 Ǻ, 5.14000 Ǻ, and 4.954610 Ǻ, were obtained. Evidence of C-H at 1338.1 cm-1, C-O at 640.0 cm-1, C-H stretch at 2829.7 cm-1, and a strong and broad O-H group at 3291.2 cm-1 were obtained. The starch granules had low particle sizes, were homogeneous, and were aggregates of irregular shapes. At a lower pH (2-4), the wild yam starch studied could be a potential absorbent material in the production of disposable diapers and female napkins and as biodegradable films due to its high hydrophobicity at a high pH (8-12).

Ozone exposure tunes the physicochemical properties of sweet potato starch by modifying its molecular structure

Ozonation is an efficient method for improving the technical performance of some starches, but the feasibility of its use for sweet potato starch remains unknown. The effects of aqueous ozonation on the multi-scale structure and physicochemical properties of sweet potato starch were explored. Structurally, ozonation did not generate significant alterations at the granular level (size, morphology, lamellar structure, and long-range and short-range ordered structures), but led to tremendous changes at the molecular level, including converting hydroxyl groups to carbonyl and carboxyl groups and depolymerizing starch molecules. These structural changes resulted in prominent alternations in the technological performance of sweet potato starch, such as increases in water solubility and paste clarity and decreases in water absorption capacity, paste viscosity, and paste viscoelasticity. For these traits, their amplitudes of variation elevated when the ozonation time was extended and peaked at the longest ozonation time (60 min). The greatest changes in paste setback (30 min), gel hardness (30 min), and the puffing capacity of the dried starch gel (45 min) were observed at moderate ozonation times. In summary, aqueous ozonation is a new method for fabricating sweet potato starch with improved functionality.