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Tese de doutoramento em Food Science and Technology and Nutrition, The production of chestnuts has increased in the last years. This fruit has interesting nutritional properties, i.e., low in fat, but rich in starch, and vitamin C. Nonetheless, chestnuts tend to spoil rapidly, which leads to a limited shelf-life. For this reason, it is important to highlight the need of studying post-harvest processing technologies capable of mitigating the decay of chestnuts and extend their shelf-life while maintaining their quality as close as possible to fresh fruits. In this context, ohmic heating (OH) and high-pressure processing (HPP) were evaluated as a post-harvest technology to improve chestnuts' shelf-life (Castanea sativa Mill.) by controlling molds and insect larvae proliferation. Moreover, the properties of HPP-treated chestnut flour and starch were evaluated. Thus, chestnuts were processed by OH at temperatures of 35, 45, and 55 °C and HPP at pressures of 400, 500, 600 MPa, and compared with control samples that were not treated and samples treated hydrothermally (HT, 50 °C for 45 min), as it is currently used by the chestnut industry. Shelf-life studies were carried out at 25 °C and 40% of relative humidity (RH), and 5 °C and 70% RH for 60 days. The results show that the processing times necessary to disinfect chestnuts were reduced by around 91% when compared to the HT. OH conducted at 55 ºC (OH-55ºC) and HPP at 600 MPa (HPP-600MPa), in combination with storage at 5 °C and 70% RH, can extend up to 60 days the chestnut shelf-life, and suppress the sprout and growth of fungi and insect larvae. The OH and HPP treatments did not affect chestnuts' nutritional quality since samples suffered minimum changes in their proximate composition. After HPP-600MPa, the relative crystallinity, amylopectin, size granules, phenols, antioxidants activity, and the pasting parameters of starch increased contrary to the amylose content, which decreased. OH and HPP are emergent technologies in food processing, demonstrates for the first time that has the potential to be used by the chestnut industry for the post-harvest disinfestation of the fruits. Moreover, HPP-600MPa is a promissory processing alternative that induces some starch modifications., A produção de castanha tem aumentado nos últimos anos. Esta fruta tem propriedades nutricionais interessantes, nomeadamente, baixa em gordura, mas rica em amido e vitamina C. No entanto, as castanhas tendem a estragar-se rapidamente, o que leva a uma vida útil limitada. Por esta razão, é importante destacar a necessidade de estudar tecnologias de processamento pós-colheita capazes de mitigar o deterioro da castanha e, ao mesmo tempo, prolongar sua vida útil mantendo a sua qualidade o mais próxima possível das frutas frescas. Nesse contexto, o aquecimento ôhmico (OH) e o processamento em alta pressão (HPP) foram avaliados como tecnologias pós-colheita para melhorar a vida útil da castanha (Castanea sativa Mill.) por meio do controle da proliferação de bolores e larvas de insetos. Além disso, foram avaliadas as propriedades da farinha e do amido de castanha tratada com HPP. Assim, as castanhas foram processadas por OH em temperaturas de 35, 45 e 55 °C e HPP em pressões de 400, 500, 600 MPa, e comparadas com amostras de controle que não foram tratadas e amostras tratadas hidrotermicamente (HT, 50 °C por 45 min), uma vez que HT é utilizado atualmente pela indústria da castanha. O estudo de vida útil foi realizado a 25 °C e 40% de umidade relativa (UR), e 5 °C e 70% UR por 60 dias. Os resultados mostram que os tempos de processamento necessários para desinfetar as castanhas foram reduzidos em cerca de 91% quando comparado com HT. OH conduzido a 55 °C (OH-55ºC) e HPP a 600 MPa (HPP-600MPa), em combinação com armazenamento a 5 °C e 70% UR, pode prolongar a vida útil da castanha em até 60 dias, e suprime o brotamento e o crescimento de fungos e larvas de insetos. Os tratamentos OH e HPP não afetaram a qualidade nutricional das castanhas, uma vez que as amostras sofreram alterações mínimas em sua composição centesimal. Após HPP-600MPa, a cristalinidade relativa, amilopectina, tamanho dos grânulos, fenóis, atividade antioxidante e os parâmetros de pasta do amido aumentaram, enquanto o conteúdo de amilose diminuiu. OH e HPP são tecnologias emergentes no processamento de alimentos, demostrando pela primeira vez que tem potencial para serem utilizadas na indústria da castanha para a desinfestação pós-colheita dos frutos. Além disso, o HPP-600MPa é uma alternativa promissora de processamento que induz algumas modificações no amido., This thesis was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 unit and BioTecNorte operation (NORTE 01 0145 FEDER 000004) funded by the European Regional Development Fund under the scope of Norte2020 Programa Operacional Regional do Norte.

The chestnut (Castanea sativa Mill.) is a seasonal product that needs a post-harvest treatment to control fungal and insect worms development in order to extend its shelf-life. Studies have demonstrated the feasibility of ohmic heating (OH) and the effects of its moderate electric fields during microbiological inactivation treatments for food applications. This emerging thermal technology can be an alternative to chestnut conventional hydrothermal treatment (HT) or to its chemical fumigation. The aim of this study was to evaluate OH capacity to extend shelf-life of chestnuts fruits by eliminating its fungal load. Five treatments were carried out: I) unprocessed chestnuts (control), II) HT (50 ℃, 45 min), III) OH at 35 ºC, IV) OH at 45 ºC and V) OH at 55 °C. The ohmic processing was conducted in a 0.5 M NaCl solution at an electric field of 9 (V/cm) for 2.00, 2.83 and 3.33 min, respectively for each temperature. Then, the chestnuts were stored for 60 days under different atmospheric conditions: i) 25°C with 40% RH, ii) 25 °C with 90% RH, and iii) 5 °C with 70% RH. Once a week the chestnuts were visually inspected for fungal and insect larvae development. Additionally, fungal load of chestnuts (log CFU/g) was determined by plating serial dilutions in RBC agar. The results showed significant differences (p>0.05) in counts of fungi between unprocessed and treated samples, in particular when the storage of chestnuts was done at 5 ºC. The OH treatment conducted at 55 ºC showed the better results; at 5 ºC and 70% RH, no fungi could be detected in samples for 60 days; while at room temperature (25 ºC), no fungi were detected for 24 days. After this period, 3.8 to 5.1 log CFU/g were detected in fruits without any visible formation of molds. The HT performed better then OH at 35 ºC, but fungi could be detected after 24 days of storage at 5 ºC (3.8 to 4.9 log CFU/g). In conclusion, OH showed to be an effective alternative HT, allowing to reduce postharvest decay of chestnuts, increase its shelf-life, and thus meet foodsafety international trade regulations., info:eu-repo/semantics/publishedVersion

This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01- 0145-FEDER-006684) and by BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 – Programa Operacional Regional do Norte. Enrique Pino Hernández is recipient of a fellowship supported by a doctoral advanced training (call NORTE-69-2015-15), funded by the European Social Fund under the scope of Norte2020 – Programa Operacional Regional do Norte., info:eu-repo/semantics/publishedVersion

The myofibrillar proteins utilization from fish processing wastes to produce films has an importance to decrease the environmental impact due to usual inappropriate disposal of these wastes. The aim of this work was to make and characterize biodegradable films developed from myofibrillar proteins of gó whitefish (Macrodon ancylodon) wastes, with anthocyanin addition as a pH change indicator. The material proteic extracted was chacterized presenting high concentration of total proteins (95.01%), important for the development of filmogenic solution. According to the results, there was a significant difference (p < 0.05) between the control and the added with anthocyanin biofilms. The film with lower concentration of anthocyanin presented better barrier property, with water vapor permeability of 3.8 × 1011 g.m1.s1.Pa1. There is a great potential for fish processing wastes utilization to obtain biodegradable films even as the anthocyanin pigment powder is promising to act as pH indicator., This work was financially supported by Project POCI-01–0145-FEDER-007457, funded by FEDER funds through “COMPETE 2020 – Programa Operacional Competitividade e Internacionalização” (POCI) and by national funds through “FCT—Fundação para a Ciência e a Tecnologia”. J.R. Carneiro would also like to thank “FCT” for the research grant SFRH/ BPD/88730/ 2012 (grant supported by POPH/POCH/FSE funding)., info:eu-repo/semantics/publishedVersion