Effect of high-pressure pre-treatment on the enzymatic activity related to quality loss in frozen hake

• Autor(a) principal: Santos, João Pedro Ferreira dos
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/25529
• topic: High Pressure Processing; Fish preservation; Merluccius merluccius; Enzymatic activity; Frozen Storage

Consumers demand for high quality food stuffs with no preservatives and with extended shelf-life, retaining the quality properties, led to the development of new processing technologies. One of those technologies, studied in this work, is High Pressure Processing (HPP), which has shown good results on fish shelf-life extension, with great importance in fish safety by inactivation of microbial load (mostly pathogenic microorganisms) in refrigerated fish, and inactivation of certain degradative enzymes, mainly in frozen fish. Fish products are usually stored under refrigeration or frozen to maintain their quality and safety patterns. However, there are still several reactions that cause fish degradation. For instance, even under frozen storage, enzymatic activity still occurs. According to the literature, HPP has shown to be a promising pre-treatment to inhibit these enzymes and extend frozen fish-shelf-life. This work aimed to determine the effect of HPP (150 MPa for 2 minutes) and storage temperature (-10, -20 and -30 ºC) on the quality of frozen hake muscle (Merluccius merluccius). It was verified that HPP resulted in a decrease of calpains activity (59 %) after 12 months of storage at -20 ºC and maintained the activity of acid phosphatase, cathepsin B and calpains after 12 months at -30 ºC Furthermore, the quantification of sulfhydryl (SH) groups indicated that the HP treatment results in higher SH content (increase up to 190%), as well as increased storage time (increase up to 120%), being this increase probably related with protein denaturation of fish muscle. This work presents relevant information concerning the employment of HP pre-treatments to reduce enzymatic activity associated to quality loss in frozen European hake (Merluccius merluccius). This type of processing can so be of interest to enhance the quality preservation of frozen hake, as well as of other species.