سیده مریم دانشور

The aim of this study was to investigate the effect of chitosan as a natural preservative. Farmed fish were washed and filleted. In this study, 3 types of chitosan were investigated: acid-soluble chitosan, water-soluble chitosan and oligosaccharide chitosan. The fillets were immersed in the above solutions for 30 seconds, and then removed, and after 2 minutes, the immersion was repeated. Control samples were uncovered. The fillets were then placed at room temperature (20 °C) for 2 hours to form a coating on the fillets. 192 pieces of 100 g fish fillets were divided into 4 treatments and each treatment was divided into 4 times: treatment one as a control (without preservative), the second treatment containing 1% acid-soluble chitosan, the third treatment containing 1% water-soluble chitosan and the fourth treatment containing 1% Chitosan oligosaccharides. All samples were stored in refrigerator at 4±1 °C and their chemical parameters (Peroxide, pH, Thiobarbituric acid, Total Volatile Nitrogen) were measured on (0, 4, 8 and 12) days. All the indices of treatments had increasing trend over time. Only in the pH index of 1% acid-soluble chitosan had an irregular trend. 1% acid-soluble chitosan had the most positive effect in all treatments. Due to increase in chemical indices in all treatments, the addition different of chitosans to fish fillets could prevent or reduce them.

The aim of this study was to investigate the effect of a natural additive called chitosan on changes of approximate composition indices (moisture, fat and protein) and pH in defrosted fish fillet (Huso huso). The study consisted of 2 treatments: chitosan-free treatment (control treatment) and 1% acid soluble chitosan treatment. Both treatments were stored at -18 ° C for 4 months. Fillets were freezed and examined on day 0 (10 hour after freezer storage) and the second and fourth months. In terms of approximate composition, the use of acid-soluble chitosan significantly caused delaying the reduction the moisture, fat, and protein content of fish fillets compared to chitosan-free fillets during freezer storage. In addition, 1% acid-soluble chitosan caused keep it low the pH of fish fillet during freezer storage compared to the control group.