Quality and shelf-life of sous-vide King crab as product in E-commerce
Bachelor thesis
Permanent lenke
https://hdl.handle.net/11250/2839542Utgivelsesdato
2021Metadata
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Sammendrag
Red king crab (RKC) is a gourmet product of economic importance, and increased distribution and sales are expected. RKC has a relatively short shelf-life after cooking and new processing and packaging solutions are requested to reach new markets. The aim of this thesis was therefore to examine processing technologies to extended shelf-life of the RKC muscle (merus) and evaluate quality and safety aspects for the chosen shelf-lives. This was done by following the sous-vide method using three different heat treatments (95 °C for 11 min, 80 °C for 4 min and 15 sec and 60 °C for 10 min and 30 sec). The heat treatments were chosen in order to inactivate 6-log of non-proteolytic Clostridium botulinum, Listeria monocytogenes and Vibrio parahaemolyticus. It was expected that treatment at 95 °C gave shelf-life of 30 days, 80 °C shelf-life of 21 days and 60 °C shelf-life of 7 days when stored at 4 °C. The microbiological quality of merus were analyzed using total viable counts (TVC) on Iron agar and Long & Hammer agar, and the presence of Bacillus colonies was detected on Pemba agar. Other quality analyses were water holding capacity (WHC), dry matter, color, drip loss and cook loss.The results showed differences in analyzed quality parameters between the treatments. Heat treatments at 60 °C and 95 °C led to a significantly (p= 0.002) higher drip. There was not detected a significantly difference in and cook loss between the different heat treatments. Drip loss did not change (p > 0.05) with time of storage. The result from WHC showed that treatment at 60 °C and 80 °C led to a significantly (p = 0.002) higher WHC than at 95 °C, and WHC increased significantly (p = 0.001) with time of storage equivalently for all treatments. Treatment at 95 °C led to a significantly (p < 0.001) higher dry matter content than treatment at 60 °C and 80 °C. Dry matter also increased significantly (p = 0.045) with time of storage equivalently for all treatments. Treatment at 95 °C led to a significantly (p = 0.002) lighter color than in merus treated at 60 °C, while merus treated at 80 °C were not significantly lighter or darker than merus treated at 60 °C or 95 °C.
Prior to the present thesis, it was not known if it was possible to remove the muscles from the exoskeleton in raw, frozen, and thawed clusters. This was examined in a preliminary experiment by using high pressure process (HPP) technology (250 MPa) to shuck the muscles from the exoskeleton. The results showed that the muscle could be removed in one piece, although it was more difficult than removal from fresh crab legs. It was therefor decided to use frozen legs in the experiments, to show that frozen legs can be used in industrial production independent of harvesting seasons of RKC.
The analyses from the storage experiment indicate that all heat treatments extended the shelf-life to the expected storage periods. The products were evaluated to be of satisfactory quality, and with further optimization of processing, this can become useful methods for industrial use. Red king crab (RKC) is a gourmet product of economic importance, and increased distribution and sales are expected. RKC has a relatively short shelf-life after cooking and new processing and packaging solutions are requested to reach new markets. The aim of this thesis was therefore to examine processing technologies to extended shelf-life of the RKC muscle (merus) and evaluate quality and safety aspects for the chosen shelf-lives. This was done by following the sous-vide method using three different heat treatments (95 °C for 11 min, 80 °C for 4 min and 15 sec and 60 °C for 10 min and 30 sec). The heat treatments were chosen in order to inactivate 6-log of non-proteolytic Clostridium botulinum, Listeria monocytogenes and Vibrio parahaemolyticus. It was expected that treatment at 95 °C gave shelf-life of 30 days, 80 °C shelf-life of 21 days and 60 °C shelf-life of 7 days when stored at 4 °C. The microbiological quality of merus were analyzed using total viable counts (TVC) on Iron agar and Long & Hammer agar, and the presence of Bacillus colonies was detected on Pemba agar. Other quality analyses were water holding capacity (WHC), dry matter, color, drip loss and cook loss.The results showed differences in analyzed quality parameters between the treatments. Heat treatments at 60 °C and 95 °C led to a significantly (p= 0.002) higher drip. There was not detected a significantly difference in and cook loss between the different heat treatments. Drip loss did not change (p > 0.05) with time of storage. The result from WHC showed that treatment at 60 °C and 80 °C led to a significantly (p = 0.002) higher WHC than at 95 °C, and WHC increased significantly (p = 0.001) with time of storage equivalently for all treatments. Treatment at 95 °C led to a significantly (p < 0.001) higher dry matter content than treatment at 60 °C and 80 °C. Dry matter also increased significantly (p = 0.045) with time of storage equivalently for all treatments. Treatment at 95 °C led to a significantly (p = 0.002) lighter color than in merus treated at 60 °C, while merus treated at 80 °C were not significantly lighter or darker than merus treated at 60 °C or 95 °C.
Prior to the present thesis, it was not known if it was possible to remove the muscles from the exoskeleton in raw, frozen, and thawed clusters. This was examined in a preliminary experiment by using high pressure process (HPP) technology (250 MPa) to shuck the muscles from the exoskeleton. The results showed that the muscle could be removed in one piece, although it was more difficult than removal from fresh crab legs. It was therefor decided to use frozen legs in the experiments, to show that frozen legs can be used in industrial production independent of harvesting seasons of RKC.
The analyses from the storage experiment indicate that all heat treatments extended the shelf-life to the expected storage periods. The products were evaluated to be of satisfactory quality, and with further optimization of processing, this can become useful methods for industrial use.