Morphology, Mechanical, and Water Barrier Properties of Carboxymethyl Rice Starch Films: Sodium Hydroxide Effect

Carboxymethyl rice starch films were prepared from carboxymethyl rice starch (CMSr) treated with sodium hydroxide (NaOH) at 10–50% w/v. The objective of this research was to determine the effect of NaOH concentrations on morphology, mechanical properties, and water barrier properties of the CMSr films. The degree of substitution (DS) and morphology of native rice starch and CMSr powders were examined. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate the chemical structure, crystallinity, and thermal properties of the CMSr films. As the NaOH concentrations increased, the DS of CMSr powders increased, which affected the morphology of CMSr powders; a polyhedral shape of the native rice starch was deformed. In addition, the increase in NaOH concentrations of the synthesis of CMSr resulted in an increase in water solubility, elongation at break, and water vapor permeability (WVP) of CMSr films. On the other hand, the water contact angle, melting temperature, and the tensile strength of the CMSr films decreased with increasing NaOH concentrations. However, the tensile strength of the CMSr films was relatively low. Therefore, such a property needs to be improved and the application of the developed films should be investigated in the future work.

Effect of Maltodextrin Replacement by Selected Native Starches and Disaccharides on Physicochemical Properties of Pumpkin Oil Capsules Prepared by Spray-Drying

The aim of the study is to compare selected carbohydrates that differed in the glycaemic index: maltodextrin, three native starches (wheat, rice, maize), and two disaccharides (trehalose and lactose) used to encapsulation of model oil (in this case cold-pressed pumpkin oil). Encapsulation efficiency of pumpkin oil by spray drying, size of obtained capsules, oxidative stability of encapsulated oil, and retention of tocopherols, squalene, and sterols in surface and core material of capsules were determined. It was found that encapsulation efficiency varied from 35% for rice starch to 68–71% for wheat starch, maltodextrin, and lactose. The bulk density of capsules was independent of the used carbohydrate type (189–198 kg/m3), while their size was significantly lower for samples of pumpkin oil encapsulated in native starches (over 2 times compared to capsules with trehalose). Of the best lipid capturing agents (native wheat starch, maltodextrin, and lactose), wheat starch mainly bound tocopherols, squalene, and sterols to the capsule surface, while lactose to the core material of the capsules (35.5–81.2%). Among tested carbohydrates, native wheat starch acted as the best antioxidant agent (oxidative stability was 15.1 h vs. 9.4 h for pure pumpkin oil).

Re-examination of the APETALA2/Ethylene-Responsive Factor Gene Family in Barley (Hordeum vulgare L.) Indicates a Role in the Regulation of Starch Synthesis

The APETALA2/Ethylene-Responsive factor (AP2/ERF) gene family is a large plant-specific transcription factor family, which plays important roles in regulating plant growth and development. A role in starch synthesis is among the multiple functions of this family of transcription factors. Barley (Hordeum vulgare L.) is one of the most important cereals for starch production. However, there are limited data on the contribution of AP2 transcription factors in barley. In this study, we used the recently published barley genome database (Morex) to identify 185 genes of the HvAP2/ERF family. Compared with previous work, we identified 64 new genes in the HvAP2/ERF gene family and corrected some previously misannotated and duplicated genes. After phylogenetic analysis, HvAP2/ERF genes were classified into four subfamilies and 18 subgroups. Expression profiling showed different patterns of spatial and temporal expression for HvAP2/ERF genes. Most of the 12 HvAP2/ERF genes analyzed using quantitative reverse transcription–polymerase chain reaction had similar expression patterns when compared with those of starch synthase genes in barley, except for HvAP2-18 and HvERF-73. HvAP2-18 is homologous to OsRSR1, which negatively regulates the synthesis of rice starch. Luciferase reporter gene, and yeast one-hybrid assays showed that HvAP2-18 bound the promoter of AGP-S and SBE1 in vitro. Thus, HvAP2-18 might be an interesting candidate gene to further explore the mechanisms involved in the regulation of starch synthesis in barley.