Contact
Aðalheiður Ólafsdóttir
Sensory evaluation manager
adalheiduro@matis.is
Chitosan treatments for the fishery industry - Enhancing quality and safety of fishery products
This report is a summary of three shelf life experiments in which seafood was treated with different chitosan solutions, either on board a fishing vessel (with shrimp and cod) or after slaughter and pre-processing of farmed salmon. This is a continuation of Matís 'report 41-12 where chitosan solutions were developed and tested on different fish products at Matís' experimental stage. The purpose of this project was to confirm the possibility of chitosan treatment of seafood in the fishing industry. The results show that the concentration of chitosan solutions and the storage temperature of seafood affect the antimicrobial activity and the deterioration of the quality of the fish products. Solutions A and B had limited activity in whole shrimp (0-1 ° C), but slower color changes occurred as the shell took on a black color. Treatment of salmon (1.4 ° C) and cod (-0.2 ° C) with solutions C and D significantly slowed the growth of erythrocytes during the first 6 days, leading to a prolongation of the freshwater phase. The storage temperature of cod fish affected the effectiveness of the solutions. When cod (2-3 ° C) was stored in worse conditions and filleted 6 days after treatment, there was a slightly lower microbial load on the fillets at the beginning of the storage period, which resulted in a slight improvement in the quality of the products. Better storage conditions are necessary to limit the effectiveness of chitosan treatment.
This report evaluates the efficiency of different chitosan treatments (A, B, C, D) when used by fishery companies, aiming to reduce seafood surface contamination and promote enhanced quality of fishery products: whole cod, shrimp and farmed salmon. The alkaline conditions establishing in chilled raw shrimp during storage (0-1 ° C) is the probable cause for no benefits of chitosan treatments A and B used shortly after catch, except for the slower blackening of head and shell observed compared to the control group . On the other hand, salmon treatments C and D were most effective in significantly reducing skin bacterial load up to 6 days post-treatment (1.4 ° C) which inevitably contributed to the extended freshness period (by 4 days) and shelf life observed. Similarly, freshness extension and delayed bacterial growth on skin was evidenced after 6 days of storage in whole cod (-0.2 ° C) treated with solution D. For cod stored at higher temperature (2-3 ° C) and processed into loins on days 3 and 6 posttreatment, a slower microbial deterioration was observed only during early storage of loins. The contribution of chitosan treatments to sensory quality enhancement was not clearly demonstrated in these products. Based on the findings, better chilling conditions should contribute to an enhanced effect of chitosan skin treatment towards quality maintenance.