Preparation, characterization and in vitro release properties of pectin-based curcumin film

Effect of Free Volume on Curcumin Release from Various Polymer-Based Composite Films Analyzed Using Positron Annihilation Lifetime Spectroscopy

This work reports the effects of free volume on curcumin release in various polymer-based composite films. Curcumin-reinforced biocomposite films were fabricated with natural biopolymers (carrageenan and chitosan) and bioplastics (poly(lactide) (PLA) and poly (butylene adipate-co-terephthalate) (PBAT)) via the solvent casting method. The curcumin release test was performed using an aqueous medium, and it was found that it was released the fastest in the carrageenan film, followed by the chitosan, PLA, and PBAT films, presumably owing to the dissimilarity of the polymer matrix. The free volume of the polymer films was determined using positron annihilation lifetime spectroscopy (PALS) to understand the release phenomena of curcumin. The free volume fraction was varied and reliant on the type of polymer, with the highest in the PBAT-based film followed by the PLA-, chitosan-, and carrageenan-based films. The free volume method helps analyze the release of bioactive compounds in a polymer matrix and may help to achieve a better understanding of the release of bioactive compounds.

Curcumin-loaded polyvinyl butyral film with antibacterial activity

Antibacterial materials have found widespread interest in different fields nowadays. In this study, curcumin (Cur) was incorporated into the polyvinyl butyral (PVB) matrix by dissolving in ethanol for improving the functional properties of a pure PVB film. We found that Cur was uniformly dispersed in the PVB matrix, which showed good compatibility. Moreover, the incorporation of Cur could also improve thermal stability, hydrophilicity, and mechanical property. The UV-vis spectra of the PVB–Cur film demonstrated that the film could block ultraviolet radiation. Subsequently, the antibacterial activity of the PVB–Cur film was measured by the colony-counting method against S. aureus and E. coli. The results showed that the PVB–Cur film exhibited good antibacterial activity. Therefore, the PVB–Cur film was considered as a promising material for food and medical packaging applications.

Production of Novel Polygalacturonase from Bacillus paralicheniformis CBS32 and Application to Depolymerization of Ramie Fiber

Polygalacturonase (EC. 3.2.1.15) is an enzyme that hydrolyzes the alpha-1,4 glycosidic bonds between galacturonic acid. In this study, an alkaline polygalacturonase producer Bacillus paralicheniformis CBS32 was isolated from kimchi (conventional Korean fermented food). The 16S rRNA sequence analysis of the isolated strain revealed that it was 99.92% identical to B. paralicheniformis KJ 16LBMN01000156. The polygalacturonase from B. paralicheniformis CBS32 was named PN32, and the purified PN32 showed a 16.8% yield and a 33-fold purity compared to the crude broth. The molecular mass, 110 kDa, was determined by SDS-PAGE, and the active band was confirmed by zymography analysis. The N-terminal amino acid sequence residues of PN32 were determined to be Gly–Val–Lys–Glu–Val–X–Gln–Thr–Phe. In the sequence comparison, PN32 was suggested as a novel polygalacturonase, since the sequence was not matched with the previous reports. In an application study, enzymatic depolymerization of ramie was performed for fiber degumming, and the result showed that the PN32 had a 28% higher depolymerization compared to the commercial pectinase. Overall, based on the results, PN32 has high potential for industrial applications.