Construction of carboxymethyl konjac glucomannan/chitosan complex nanogels as potential delivery vehicles for curcumin.

Construction of nanoscale delivery systems from natural food biopolymer complexes have attracted increasing interests in the fields of food industries. In this study, novel carboxymethyl konjac glucomannan/ chitosan (CMKGM/CS) nanogels with and without 1-ethyl-3-(3-dimethylaminopropyl) /N-hydroxysuccinimide) (EDC/NHS)-initiated crosslinking were prepared. The physicochemical and structural properties of the CMKGM/CS nanogels and their potential to be a delivery vehicle for curcumin were investigated. Compared to original uncrosslinked nanogels, crosslinking did not alter particle size and morphology but decreased zeta potential of nanogels. Fourier transform infrared spectrum confirmed that the amide linkage was formed between CMKGM and CS, which obviously enhanced the stability of crosslinked nanogels under gastrointestinal conditions. Furthermore, the crosslinked nanogels not only had higher encapsulation efficiency of curcumin but also better sustained release behavior under simulated gastrointestinal conditions. These findings suggested that the crosslinked CMKGM/CS nanogels might be a promising delivery system for nutrients.

Transparent bionanocomposite films based on konjac glucomannan, chitosan, and TEMPO-oxidized chitin nanocrystals with enhanced mechanical and barrier properties.

The development of biopolymer-based films for food packaging is increasing owing to their environmental appeal, renewability, and biodegradability. In this study, transparent and biodegradable konjac glucomannan (KGM)/chitosan (CS)/TEMPO-oxidized chitin nanocrystal (TEMPO-ChNCs) bionanocomposite films were prepared. The TEMPO-ChNCs were prepared from chitin using the 2,2,6,6-tetramethylpiperidine-1-oxylradical (TEMPO) oxidation method and were used as a reinforcement nanofiller for the bionanocomposite films. The effect of TEMPO-ChNCs content on both rheological properties of film-forming solutions (FFS) and structural and physical properties of the resultant films was investigated. The rheological results of the FFS revealed that the TEMPO-ChNCs interacted with KGM and CS through electrostatic interaction and the hydrogen bonds in the bionanocomposite matrix, which was in agreement with the Fourier transform infrared spectroscopy and X-ray diffraction results. The microstructure of the films showed that 3% (w/w) TEMPO-ChNCs were homogeneously dispersed within the KGM/CS matrix, reducing the free volume of the biocomposite matrix and improving the final film mechanical and barrier properties (P < 0.05). Furthermore, these bionanocomposite films exhibited good thermal stability. The incorporation of TEMPO-ChNCs in the KGM/CS matrix produced flexible and transparent bionanocomposite films. Thus, this bionanocomposite films has potential use in food packaging applications.

Fabrication of novel Konjac glucomannan/shellac film with advanced functions for food packaging.

In this study, a novel composite film was fabricated from Konjac glucomannan (KGM) combined with shellac (SHL) via a casting and solvent evaporation method. Rotary rheometry, field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) were applied to characterize the structure of the film. Physical properties were also investigated to evaluate the effect of SHL on KGM-based films. The results indicated that KGM-SHL gels exhibit a shear-thinning behaviour when the shear rate is increased. Meanwhile, FE-SEM images confirmed that all blended films had a continuous and homogeneous appearance without phase separation. The newly formed chemical bonds after blending were observed by FTIR. Moreover, thermal tolerance and mechanical properties of the films, such as tensile strength and elongation at break, were improved by adding SHL. In addition, the presence of SHL in the films led to an increase in water resistance. Therefore, the improved KGM-SHL films can be considered as a potential material for food packaging.

Preparation of an intelligent film based on chitosan/oxidized chitin nanocrystals incorporating black rice bran anthocyanins for seafood spoilage monitoring.

A novel intelligent film was developed by immobilizing 1%, 3% and 5% black rice bran anthocyanins (BACNs) into oxidized-chitin nanocrystals (O-ChNCs)/ chitosan (CS) matrix. The ultraviolet-visible spectrum of BACNs solutions showed color variations from red to greyish green in a range of pH 2.0-12.0. Fourier transform infrared spectrum and atomic force microscope of the films showed that O-ChNC and BACNs were well dispersed into the CS matrix. Although the incorporation of BACNs decreased the mechanical and barrier properties of the CS/O-ChNCs/BACNs (COB) films, it endowed the COB films with excellent UV-barrier, antioxidant and pH sensitivity character. The results of the application trial showed that the COB films containing 3% of BACNs (COB-3) were able to monitor the spoiling of fish and shrimp by visible color changes. Therefore, the developed COB-3 films could be used as an intelligent food packaging for monitoring animal-based protein food spoilage.