Chitooligosaccharides suppress the freeze-denaturation of actomyosin in Aristichthys nobilis surimi protein.

Effect of chitooligosaccharides on the denaturation of bighead carp (Aristichthys nobilis) surimi protein during frozen storage at -18 °C was investigated. The addition of 4 g of chitooligosaccharides to 100 g of the bighead carp (A. nobilis) surimi effectively inhibited the inactivation of the Ca(2+)-ATPase during frozen storage at -18 °C for 15 days compared to the control group (p<0.05), while excessive chitooligosaccharides decreased the inhibition effect. The Ca(2+)-ATPase activity of actomyosin for the treatment group decreased gradually during frozen storage at -18 °C, while that of the control dropped drastically and could not be detected after 30 days of storage. On the other hand, the addition of chitooligosaccharides also significantly increased the solubility of actomyosin compared to the control group (p<0.05) during frozen storage at -18 °C up to 120 days.

Preparation of chitooligosaccharides from cicada slough and their antibacterial activity.

In this study, chitooligosaccharides were prepared from cicada slough of Cryptotympana atrata Fabricius by hydrolysis using hydrogen peroxide (H2O2). Factors affecting the hydrolysis of chitosan were investigated and the optimum hydrolysis conditions were as follows: time, 4 h; temperature, 65 °C; amount of H2O2, 2% (v/v); and pH, 5. Under these conditions, the average degree of polymerisation decreased to ~4.5. The Fourier transform infrared spectra and product sugar composition indicate that there were no significant chemical changes in the backbones of the chitosan treated with H2O2.The chitooligosaccharides had high antibacterial activity against Bacillus subtilis, Staphylococcus aureus, and Escherichia coli at the concentration of 100mg/mL.

Preparation of peach gum polysaccharides using hydrogen peroxide.

Most polysaccharides cannot dissolve in water but can be hydrolysed using hydrogen peroxide (H2O2) to yield a water-soluble product. This study presents a method of preparing water-soluble polysaccharides from peach gum by hydrolysis using H2O2. Extraction was monitored by the recovery rate. Factors affecting the hydrolysis of peach gum were investigated, and the optimum hydrolysis conditions were determined as follows: time, 8 h; temperature, 55°C; H2O2 concentration, 4% (v/v); and NaOH concentration, 2.0 M. The hydrolysates were filtered, neutralised with HCl, concentrated to ∼20% (w/v), precipitated with 5 volumes of ethanol, freeze-dried, and ground to yield a water soluble and white powder. The polysaccharide content of the product was 97.8%, and the yield was 83.6% (w/w).

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.