Biochemical and colour changes of watercress (Nasturtium officinale R. Br.) during freezing and frozen storage

• Autor(a) principal: Gonçalves, E.M.
• Data de Publicação: 2009
• Outros Autores: Cruz, R.M.S., Abreu, M., Brandão, Teresa R. S., Silva, Cristina L.M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.14/2678
• topic: Frozen watercress; Quality parameters; Peroxidase activity; Kinetics

The effects of water blanching, freezing, and frozen storage during 400 days at three different temperatures ( 7, 15 and 30 C), on watercress (Nasturtium officinale R. Br.) colour Hunter Lab parameters,chlorophyll degradation, vitamin C content loss and peroxidase (POD) activity were evaluated. The blanching induced significant changes on colour values and chlorophylls and vitamin C contents. POD activity was reduced 85% from its initial value. Freezing did not affect chlorophylls and vitamin C levels, however, promoted significant differences in colour values and POD residual activity. During frozen storage, ascorbic acid (AA) and POD activity Degradations followed first-order kinetics, and colour parameters (LH aH bH, aH/bH, LH aH/bH, LH/aH bH and hue (h0 H)) were successfully described by zero-order kinetics. The storage temperature effect was successfully described by the Arrhenius law. Chlorophylls and dehydroascorbic acid (DHAA) contents were kept constant during frozen storage.