Freezing effects of raw materials on threadfin bream surimi gel quality

Threadfin bream (Nemipterus spp.) were bought from the landing pier and used as raw materials for frozen surimi production. The fishes were frozen at -36°C until the center of the fish was cooled to -18"C. The frozen fish were kept at -18±1°C for 0, 20, 40 days, then the fish were taken and processed to surimi. The frozen surimi were kept at -18±1°C for 0, 1½ and 3 months. The results showed that surimi made from 40 days cold-stored fish have more yellowness in colour than the zero- day fish. Gel forming ability of surimi was affected by the storage time of both frozen fish and frozen surimi. Gel strength of kamaboko made from prolonged-storage surimi was lower than zero-month-stored surimi. However, the folding test still registered AA after prolonged storage of surimi made from frozen fish of 21 days to 3 months. It is recommended that frozen threadfin bream can be used for surimi processing; this surimi should be directly processed to fish jelly products as soon as possible in order to obtain good gel-forming ability. To improve the gel-forming ability of minced fish, ascorbic acid was added at 0.1 and 0.2% by weight during the mixing process. After production, surimi were kept frozen for 1½ months. It was found that 0.1% by weight of ascorbic acid improved the gel quality of frozen stored surimi. Increasing the amount of ascorbic acid to 0.2% resulted in lowering the pH of surimi. It also lowered the gel strength of prepared kamaboko

Porous hydrogels from shark skin collagen crosslinked under dense carbon dioxide atmosphere

The possibility to fabricate marine collagen porous structures crosslinked with genipin under high pressure carbon dioxide is investigated. Collagen from shark skin is used to prepare prescaffolds by freeze-drying. The poor stability of the structures and low mechanical properties require crosslinking of the structures. Under dense CO2 atmosphere, crosslinking of collagen pre-scaffolds is allowed for 16 h. Additionally, the hydrogels are foamed and the scaffolds obtained present a highly porous structure. In vitro cell culture tests performed with a chondrocyte-like cell line show good cell adherence and proliferation, which is a strong indication of the potential of these scaffolds to be used in tissue cartilage tissue engineering.The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no. KBBE-2010-266033 (project SPECIAL) and from FEDER through POCTEP Project 0330_IBEROMARE_1_P. Portuguese Foundation for Science and Technology is also gratefully acknowledged for post-doc grants of J. Moreira-Silva and T.H. Silva