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Browsing by Author "Santos, Catarina Filipa Cunha"

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  • Development of k-carrageenan films incorporating Cymbopogon winterianus and Lavandula viridis essential oils for food packaging applications
    Publication . Santos, Catarina Filipa Cunha; Amaral, Maria Emilia da Costa Cabral; Luís, Ângelo Filipe Santos
    From the XX century onwards, the innovation of plastics brought a global revolution, playing a fundamental role in improving comfort and practicality and minimizing food waste. However, this breakthrough had substantial drawbacks, most notably widespread pollution. The growing recognition of the damage caused by plastics to the ecosystem has driven scientific research and the exploration of sustainable alternatives, with a particular focus on food packaging. In the context of this complicated and diverse challenge, the purpose of this investigation was to create and characterize k-carrageenan films containing essential oils of Cymbopogon winterianus and Lavandula viridis. The aim is to use these films to produce a biodegradable material that can extend the shelf life of packaged foods. The essential oils were chemically characterized to identify and quantify the total and predominant chemical compounds. The antioxidant and antimicrobial properties of the essential oils have also been studied. The major compound in C. winterianus essential oil is citronellal, which has significant antioxidant activity, as demonstrated by the DPPH• assay and the ß-carotene bleaching test. This essential oil performed well against Listeria monocytogenes LMG 16779, which suggests it has antibacterial properties. The main composition of L. viridis essential oil is 1,8- cineole, which performed well in the DPPH• evaluation and had lower values than the previous essential oil in the ß-carotene bleaching test. This essential oil showed a similar result to the previous one against the same strain for the antibacterial test. The antioxidant, antibacterial, barrier and physical properties were studied for the films produced. Changes in the composition of the films were evaluated using FTIR. Carrying out tensile tests on the samples allowed us to infer that the films incorporated with essential oils lost, in general, part of their resistance when compared to the control film. In terms of antioxidant tests, the results for DPPH• were satisfactory, but the results for C. winterianus were more promising in terms of ß-carotene, as less of it is needed to exert an antioxidant effect. In antibacterial tests, the layer of action by L. monocytogenes LMG 16779 is evident for both films. This result was validated with the anti-biofilm test, through the formation of biofilms on the surface of the films, subsequently visualized in the SEM, showing a clear reduction in the number of bacteria. Finally, a test was carried out in a food model, in which sliced cheese samples were packaged with the films produced, kept at 4ºC for 15 days, and then observed. The results showed that no visible signs of rot or mold were found in the cheese.
    2023-11-28Master thesis Open access Show more