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Percorrer por autor "Kirby, Roy"

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  • Changes in the ceIl membrane of Lactobacillus bulgaricus during storage following freeze-drying
    Publication . Castro, Helena P.; Teixeira, Paula; Kirby, Roy
    The mechanism of inactivation of freeze-dried Lactobacillus bulgaricus during storage in maltodextrin under controlled humidity was investigated. Evidence is presented supporting the hypothesis that membrane damage occurs during storage. A study on the lipid composition of the cells by gas chromatography showed a decrease in the unsaturated and saturated fatty acid content of the cell. Further evidence indicating membrane damage includes a decrease in membrane bound proton-translocating ATPase activity.
    1996Artigo científico Acesso aberto Ver mais
  • Low-level heat-treatment to extend shelf-life of fresh fish
    Publication . Vaz-Pires, Paulo; Capell, Christopher; Kirby, Roy
    The application of heat to reduce the microbial load and extend the lag phase was studied on whole fish and with bacterial isolates from fresh fish in mixed culture. Bacterial isolates obtained from fresh horse-mackerel (Trachurus trachurus) were heat treated at 60°C for 20s and stored in nutrient broth on ice. the flora were shown to be heat sensitive and the initial numbers were reduced by over 2.0 log10 cycles. Heating at 60°C extended the lag phase but subsequent growth rates were increased, giving a shelf-life extension of a day and a half. There were no significant effects on visual EC grades of whole fish or on the flavour of cooked fillets.
    1994Artigo científico Acesso restrito Ver mais