POLYPHENOL OXIDASE CHANGE IN READY-TO-USE MARINATES ANCHOVIES AND SARDINES

Blue-fish is particularly abundant in the Ionian Sea and generally consumed as fresh, canned or salted product. According to the amount of anchovies and sardines available, there is a possibility of developing new products. One possible commercial alternative is the production of marinated ready-to-use blue-fish. Nevertheless, polyphenol oxidase (PPO, EC 1.14.18.1) is an enzyme producing pigments responsible for the undesirable dark colors which spoiled these products. This research aimed at assessing the efficacy as anti-browning agents of citric acid and marination in ready-to-use anchovy and sardine fillets compared to the untreated controls throughout a 5-days chilling storage. The results showed that no significant differences (p≥ 0.05) were noticed in gas concentration (O2 and CO2) inside the bags during storage. Each anti-browning treatment (citric acid or acidification and marination) produced a significant (p≤ 0.05) PPO inhibition. The greatest enzymatic reduction as compared to the untreated control samples was observed in marinated anchovies stored up to 4 days. The effectiveness of the preservation treatment with citric acid was confirmed in terms of color parameters, whereas the addition of sunflower oil in marinated blue-fish ‘masked’ their chromatic changes during storage. Data suggested industrial applications, e.g. the addition of one or more PPO inhibitors into blue-fish packages.