Functional properties of protein hydrolysates from Riceberry rice bran

Protein hydrolysate from pigmented Riceberry rice bran has great potential to be used in food products due to its protein content and antioxidative activities. In this study, characteristics, solubility, heat stability and emulsification properties of protein hydrolysates from the bran fraction of two rice cultivars, commercial rice bran (CBH) and Riceberry bran (RBH), were investigated. Both CBH and RBH showed the lowest solubility near their isoelectric point between pH 2 and 3. Solubility of RBH increased with increasing pH as the hydrolysates became more negatively charged; however, solubility of CBH was less dependent on pH. Heating did not significantly affect solubility of both hydrolysates which could be due to reduced aggregation of low‐molecular weight peptides and/or the exposure of charged and polar groups after hydrolysis. Oil‐in‐water emulsions stabilised by RBH were more stable compared to those stabilised by CBH. Maximum stability was achieved with RBH at pH 6 where no creaming was observed after 14 day storage. Higher stability could be due to increased surface protein coverage, more negative charge and higher viscosity of RBH‐stabilised emulsions. In addition, higher carbohydrate content and the presence of flavonoid could also contribute to an increase in stability. These results can be applied in food products using rice bran protein hydrolysate as nutritional ingredients.     

Cobalt-containing spherical glass nanoparticles for therapeutic ion release

Bioactive glass nanoparticles (BGNPs) can be internalized by cells, allowing the intracellular release of dissolution products with therapeutic benefit. Different therapeutic ions can be incorporated into the glass network that can promote angiogenesis via simulation of hypoxia conditions and consequent activation of pro-angiogenic genes. Here, novel monodispersed spherical dense BGNPs were obtained by a modified Stöber method with the SiO₂–CaO–CoO composition, with diameters of 92 ± 1 nm, with cobalt as the pro-angiogenic ion. The presence of Co²⁺ species and the role of Co and Ca as network modifiers in the silica glass were confirmed by X-ray photoelectron spectroscopy and ²⁹Si solid-state magic-angle spinning nuclear magnetic resonance, respectively. Controlled Co²⁺ ion release was observed in culture media, and no cytotoxicity was observed by (4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cell viability assay on human osteosarcoma cells in direct contact with the nanoparticles. This study demonstrated that Co²⁺ ions can be incorporated into dense and spherical BGNPs, and these materials exhibit great potential as intracellular ion delivery systems with therapeutic properties.     

Extraction and characterisation of Riceberry bran protein hydrolysate using enzymatic hydrolysis

Riceberry bran protein hydrolysate (RBPH) was prepared from bran of purple‐pigmented Riceberry rice using enzymatic hydrolysis. The effect of enzyme type (Alcalase, Flavourzyme and Neutrase) and hydrolysis time (2, 4 and 6 h) on protein content, protein yield, total phenolic content (TPC), antioxidant activities (ABTS and FRAP) and molecular weight patterns of RBPH was investigated. The enzyme type significantly (P < 0.05) affected the properties of RBPH whereas the hydrolysis time had no significant effect (P ≥ 0.05) on those properties. Flavourzyme was the most effective to increase protein yield, TPC and antioxidant activities compared to Alcalase and Neutrase. The optimal hydrolysis condition was 4 h using Flavourzyme which yielded 74.9% extracted protein. This hydrolysate contained peptides ranging from 16 to 64 kDa. The high antioxidant activity was related to negative charge peptides as shown by anion exchange chromatography. With high protein content and antioxidant properties, RBPH using Flavourzyme could be practically utilised in functional foods.     

Investigation on ferromagnetic and ferroelectric properties of (La,K)-doped BiFeO3–BaTiO3 solid solution

Multiferroic materials of BiFeO₃–BaTiO₃ solid solution have been fabricated in order to improve ferromagnetic and ferroelectric properties. The effects of La (1 mol%) and K (varied from 0.5–5 mol%) doped 0.75BiFeO₃–0.25BaTiO₃ on phase formation, ferromagnetic and ferroelectric properties have been investigated and discussed. The rhombohedral perovskite phase of specimens was characterized by XRD technique. Fracture morphology reveals the grain growth characteristics with increasing K content. (La, K)-doped 0.75BiFeO₃–0.25BaTiO₃ with La=1 mol% and K=3 mol% exhibits the highest remnant polarization and remnant magnetization.     

Biochemical changes in fermented rice-shrimp (Macrobrachium idella) mixture: Changes in protein fractions

Rice-shrimp mixture was allowed to under go natural fermentation for 10 days at 31°C. Daily biochemical tests were carried out in fermented rice-shrimp mixture for 10 days.The protein fractions, particularly soluble-nitrogen, increased from the beginning until the end of the fermentation period. The same pattern also occurred with amino-nitrogen formation concomitant with the reduction in molecular weight of shrimp protein. Ammonia-nitrogen was produced in small amounts and reached a maximum on the seventh day. Cathepsin D activity in shrimp had an optimum pH of 3·5 and an optimum temperature of 40°C. The activity of this enzyme decreased with fermentation time.     

Poly(ethylene glycol) methyl ether methacrylate‐graft‐chitosan nanoparticles as a biobased nanofiller for a poly(lactic acid) blend: Radiation‐induced grafting and performance studies

In this study, we aimed to modify chitosan (CS) as a novel compatible bio‐based nanofiller for improving the compatibility including the thermal and mechanical properties of poly(lactic acid) (PLA). The modification of CS with poly(ethylene glycol) methyl ether methacrylate (PEGMA) was done by radiation‐induced graft copolymerization. The effects of the dose rate, irradiation dose, and PEGMA concentration on the degree of grating (DG) were investigated. The chemical structure, packing structure, thermal stability, particle morphology, and size of the PEGMA‐graft‐chitosan nanoparticles (PEGMA‐graft‐CSNPs) were characterized by fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The compatibility of the PEGMA‐graft‐CSNP/PLA blends was also assessed by field emission scanning electron microscopy. The PEGMA‐graft‐CSNPs exhibited a spherical shape with the DG and particle sizes in the ranges of 3–145% and 35–104 nm, respectively. The PEGMA‐graft‐CSNPs showed compatible with PLA because of the grafted PEGMA segment. A model case study of the PEGMA‐graft‐CSNP/PLA blend demonstrated the improvement not only the compatibility but also thermal stability flexibility, and ductility of PLA. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42522.