Bio-nano-composites containing at least two components, chitosan and zein, for food packaging applications: A review of the nano-composites in comparison with the conventional counterparts.

Both chitosan and zein are safe industrial biopolymers for the 21St century, respecting environmentally concerns. This review mainly is focused on preparations, properties and applications of a promising food packaging material, chitosan-zein nano-composite (NC). The properties and applications of the NCs were compared with their conventional counterparts.

Fragmentation of chitosan by acids.

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by (1)H NMR spectroscopy and elemental analysis.

Various methods for determination of the degree of N-acetylation of chitin and chitosan: a review.

Chitin, chitosan, and their derivatives have been identified as versatile biopolymers for a broad range of agriculture and food applications. Up to now, several methods have been developed to determine degree of N-acetylation, DA, for chitin and chitosan. In this article, an effort has been made to review the available literature information on the DA determination.

Fragmentation of chitosan by ultrasonic irradiation.

Kinetics of chitosan fragmentation by ultrasonic irradiation at frequency of 20 kHz, and the effects of experimental variables (power of ultrasound, chitosan concentration and solution temperature) on fragmentation were investigated. The kinetics studies were followed by measuring solution viscosity of the original and its fragments, and determining average number of chain scission of the fragments. The effects of ultrasonic power, chitosan concentration and solution temperature on fragmentation process were followed by viscometry and size exclusion chromatography.

Calculation of viscometric constants, hydrodynamic volume, polymer-solvent interaction parameter, and expansion factor for three polysaccharides with different chain conformations.

The viscometric constants, K and a, for three polysaccharides: hydroxyethylcellulose (HEC); hydroxypropylcellulose (HPC); and chitosan, were calculated at 30 degrees C using intrinsic viscosity, [eta] and molecular weight (M(n), M(w), M(z)) data. The polydispersity correction factor, q(MHS), and hydrodynamic volume for each polymer sample were also calculated. The value of q(MHS) for the polymer samples was taken into account in the calculation of the viscometric constants.

Theoretical investigation of hydrogen bonding effects on oxygen, nitrogen, and hydrogen chemical shielding and electric field gradient tensors of chitosan/HI salt.

A density functional theory study has been carried out to calculate the (17)O, (15)N, (13)C, and (1)H chemical shielding as well as (17)O, (14)N, and (2)H electric field gradient tensors of chitosan/HI type I salt. These calculations were performed using the B3LYP functional and 6-311++G (d,p) and 6-31++G (d,p) basis sets. Calculated EFG and chemical shielding tensors were used to evaluate the (17)O, (14)N, and (2)H nuclear quadruple resonance, NQR, and (17)O, (15)N, (13)C, and (1)H nuclear magnetic resonance, NMR, parameters in the cluster model, which are in good agreement with the available experimental data.