Preparation of water-soluble chitosan by hydrolysis with commercial glucoamylase containing chitosanase activity

Chitooligosaccharides from squid pen prepared using different enzymes: characteristics and the effect on quality of surimi gel during refrigerated storage

Abstract

Chitooligosaccharides (COS) from squid pen produced using amylase, lipase and pepsin were characterized. COS produced by 8% (w/w) lipase (COS-L) showed the maximum FRAP and ABTS radical scavenging activity than those prepared using other two enzymes. COS-L had the average molecular weight (MW) of 79 kDa, intrinsic viscosity of 0.41 dL/g and water solubility of 49%. DPPH, ABTS radical scavenging activities, FRAP and ORAC of COS-L were 5.68, 322.68, 5.66 and 42.20 μmol TE/g sample, respectively. Metal chelating activity was 2.58 μmol EE/g sample. For antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of COS-L against the targeted bacteria were in the range of 0.31–4.91 mg/mL and 0.62–4.91 mg/mL, respectively. Sardine surimi gel added with 1% (w/w) COS-L showed the lower PV, TBARS and microbial growth during 10 days of storage at 4 °C. COS-L from squid pen could inhibit lipid oxidation and extend the shelf-life of refrigerated sardine surimi gel.

Graphical abstract

Fast dissolving oral films for drug delivery prepared from chitosan/pullulan electrospinning nanofibers

In this study, Chitosan/pullulan composite nanofiber fast dissolving oral films (FDOFs) were prepared via electrospinning technology. The ratio of chitosan/pullulan (C/P) had an influence on solution property and nanofiber morphology, with the increase of chitosan, viscosity and conductivity of solutions increased, the morphology obtained by scanning electron microscopy indicated that the diameter of nanofibers decreased initially then increased. The Fourier transform infrared spectra indicated hydrogen bond interactions between chitosan and pullulan molecules. X-ray diffraction analysis proved that electrospinning process decreased the crystallinity of materials. Thermal analysis showed that melting point, degradation temperature and glass transition temperature increased with the addition of chitosan content in the FDOF. Water solubility test proved that the FDOF can dissolve in water completely within 60 s. Finally, in order to prove its practicability in future, a model drug of aspirin was encapsulated in the FDOF successfully.

Preparation of glucosamine by hydrolysis of chitosan with commercial α-amylase and glucoamylase

OBJECTIVE

In order to overcome the defects of chemical hydrolysis approach to prepare glucosamine, an enzymatic hydrolysis method was developed.

METHODS

Glucosamine was prepared by hydrolyzing chitosan, employing α-amylase initially, and subsequently, glucoamylase.

RESULTS

The optimal hydrolyzing conditions were as follows: reaction time, 4 h; pH, 5.0; temperature, 50 °C; and, α-amylase, 80 U/g for the initial reaction. Subsequently, glucoamylase was added in the presence of α-amylase. The optimal reaction conditions were found to be: reaction time, 8 h; pH, 4.5; temperature, 55 °C; and, glucoamylase, 4000 U/g. The hydrolysates were subject to filtrating, concentrating to about 20% (w/w), precipitating with five volumes of ethanol, and drying at 60 °C for 2 h. The content and the yield of glucosamine in the dried precipitate were 91.3% (w/w) and 86.2% (w/w), respectively.

CONCLUSIONS

The method developed in this study is a promising option in the preparation of glucosamine.