Percorrer por autor "Isidoro, Nélson"
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- Antioxidant extracts from natural sources as potential enzymatic browning inhibitors in fruitsPublication . Dias, Cindy; Amaro, Ana; Salvador, Ângelo C.; Rocha, Sílvia M.; Silvestre, Armando J. D.; Isidoro, Nélson; Pintado, Manuela
- Atmosfera controlada dinâmica na prevenção do acastanhamento interno em pera rocha: eficácia dos sensores de etanol e de fluorescência de clorofilasPublication . Deuchande, Teresa; Carvalho, Susana M. P.; Larrigaudière, Christian; Fidalgo, Fernanda; Guterres, Umbelina; Isidoro, Nélson; Vasconcelos, MartaA pera ‘Rocha’ é suscetível ao desenvolvimento de acastanhamento interno (AI) durante o armazenamento prolongado em atmosfera controlada estática (ACE). Este estudo teve como objetivo avaliar o potencial da atmosfera controlada dinâmica (ACD) monitorizada por dois tipos de sensor (etanol e fluorescência de clorofilas) na prevenção do AI em pera ‘Rocha’, com enfase no metabolismo fermentativo e sistema antioxidante. Neste estudo, peras de um pomar foram armazenadas em três câmaras comerciais de atmosfera controlada durante 145 dias, com as seguintes condições de armazenamento: 1) ACD monitorizada por um sensor de etanol (ACD-EtOH); 2) ACD monitorizada por um sensor de fluorescência de clorofilas (ACD-FC); 3) ACE. No final do armazenamento os frutos em ACD-FC e ACE não foram afetados por AI, ao contrário dos frutos armazenados em ACD-EtOH, os quais apresentaram uma incidência de 15% após 125 dias e 20% após 145 dias de armazenamento. A elevada incidência de AI nos frutos armazenados em ACD-EtOH após 125 dias pareceu estar maioritariamente relacionada com os elevados níveis de etanol observado nestes frutos, comparativamente com os níveis detetados nos frutos da ACD-FC e ACE. Embora, após 125 dias, tenha ocorrido uma diminuição dos níveis de ácido ascórbico nos frutos da ACD-EtOH, após 145 dias os frutos superaram este decréscimo e os valores foram superiores aos registados nos frutos das outras condições de armazenamento. Estes resultados sugerem que a utilização do sensor de fluorescência de clorofilas para ajustar os níveis de oxigénio durante o armazenamento em ACD é uma estratégia eficaz na prevenção do AI em pera "Rocha". Pelo contrário, a informação dada pelo sensor de etanol parece ser insuficiente para evitar a indução do metabolismo fermentativo. Os resultados sugerem ainda, que a principal causa do AI em pera ‘Rocha’ poderá estar, primariamente relacionada com o metabolismo fermentativo.
- Evaluation of natural extracts as potential enzymatic browning inhibitorsPublication . Dias, Cindy; Amaro, Ana; Salvador, Ângelo; Rocha, Sílvia; Silvestre, Armando; Isidoro, Nélson; Pintado, ManuelaEnzymatic browning in fruits represents a difficult problem for Food Industry, especially with recent restrictions in the use of synthetic antioxidants. It is often associated with undesirable off-flavors and negative effects on taste and nutritional value. This physiological disorder is mainly due to the oxidation of natural phenolic compounds into quinones that are polymerized to brown pigments by polyphenol oxidase (PPO). Peroxidase (POX) is also alleged to be related to browning development, by inducing H2O2 oxidation of phenolic compounds. Prevention of browning reactions, catalyzed by these enzymes, has traditionally been accomplished by various chemicals, as ascorbic and citric acids. Partial control of this disorder can be obtained with the application of antioxidants, which compete with common substracts for the enzymatic activity. This study assessed the potential of natural extracts, with antioxidant properties (such as soy protein concentrate, extracts of apple byproduct and olive leaves) as novel enzymatic browning inhibitors. The antioxidant capacity was assessed by the radical scavenging assay using ABTS+ radical. The natural extracts inhibitory effect on PPO and POX activity was evaluated using a spectrophotometric assay by reaction of the natural extracts with the pure enzymes, using catechol and guaiacol as substrates, respectively. The present study demonstrated that olive leaves had the highest antioxidant capacity (2.688 ± 0.006 mg/mL TEAC equivalent), however, apple byproduct was the most effective on PPO and POX activity inhibition. The study has practical implications in generating novel natural extracts with potential application as anti-browning agents.
- Natural-based antioxidant extracts as potential mitigators of fruit browningPublication . Dias, Cindy; Fonseca, Alexandre M. A.; Amaro, Ana L.; Vilas-Boas, Ana A.; Oliveira, Ana; Santos, Sónia A. O.; Silvestre, Armando J. D.; Rocha, Sílvia M.; Isidoro, Nélson; Pintado, ManuelaFruit enzymatic browning (EB) inhibition continues to be a challenge in the Food Industry. This physiological disorder results mainly from the oxidation of natural phenolic compounds by polyphenoloxidase (PPO) and peroxidase (POX) leading to the formation of brown pigments. EB can be controlled with the application of antioxidants, reducing/inhibiting the activity of these oxidative enzymes. In this study, strawberry tree (leaves and branches) and apple byproduct were the natural-based extracts (NES) selected, as potential tissue browning inhibitors, within a first screening of fifteen natural-based extracts with antioxidant properties. Phenolic profile, total phenolic content and antioxidant activity of the selected extracts were also performed as well as their depletion effect on the oxidative enzyme’s activity and browning inhibiton in fresh-cut pears. Strawberry tree extracts (leaves and branches) revealed higher total phenolic content (207.97 ± 0.01 mg GAE.gNES−1 and 104.07 ± 16.38 mg GAE.gNES−1, respectively), confirmed by the plethora of phenolic compounds identified by LC-ESI-UHR-QqTOF-HRMS and quantified by HPLC. This phytochemical composition was reflected in the low IC50 against PPO and POX obtained. Despite the lower phenolic content (6.76 ± 0.11 mg GAE.gNES−1) and antioxidant activity (IC50 = 45.59 ± 1.34 mg mL−1), apple byproduct extract showed potential in delaying browning. This study highlights the opportunity of byproducts and agricultural wastes extracts as novel anti-browning agents.
- ReStoragePear: development of strategies to the prevention of superficial scald and internal browning in the Rocha pear and quality assurance in long-term storagePublication . Dias, Cindy; Amaro, Ana; Salvador, Ângelo; Rocha, Sílvia M.; Silvestre, Armando; Isidoro, Nélson; Pintado, Manuela
- ß-Farnesene exogenous application as a novel damage induction model to fast explore the effectiveness of postharvest strategies: the case study of the ‘Rocha’ pear DOPPublication . Dias, Cindy; Amaro, Ana; Fonseca, Alexandre; Ferrante, António; Silvestre, Armando; Rocha, Sílvia M.; Isidoro, Nélson; Pintado, ManuelaSince the prohibition of diphenylamine, replacement strategies have been needed for long-term disorder prevention, namely superficial scald (SC), in fruit. However, as this disorder only appears after months under cold storage, the assessment of effective strategies to prevent this disorder requires long periods. To tackle this challenge, we report in this paper a rapid and reliable system to induce symptoms, such as SC, based on storage under a β-farnesene-enriched atmosphere. Using this model, SC symptoms in ‘Rocha’ pear were induced after 15 d at 20◦ C. As proof of concept, this model system allowed the study of the efficiency of antioxidant natural-based coatings on ‘Rocha’ pear quality maintenance. Pears treated with the coatings were submitted to 4 months of commercial storage under normal atmosphere conditions and the results were compared with those obtained using the induction model system. A PCA of chemical data allowed us to conclude that the model developed simulates the potential of certain strategies to prevent disorders.
- Strategies to preserve postharvest quality of horticultural crops and superficial scald control: from diphenylamine antioxidant usage to more recent approachesPublication . Dias, Cindy; Amaro, A. L.; Salvador, Ângelo C.; Silvestre, Armando J.D.; Rocha, Sílvia M.; Isidoro, Nélson; Pintado, ManuelaHorticultural crops are vulnerable to several disorders, which affect their physiological and organoleptic quality. For about forty years, the control of physiological disorders (such as superficial scald) in horticultural crops, particularly in fruit, was achieved through the application of the antioxidant diphenylamine (DPA), usually combined with controlled atmosphere (CA) conditions. However, identification of DPA residues and metabolites in treated fruits, associated with thei toxicity, banned the use of this antioxidant in Europe. This triggered the urgent need for novel and, ideally, natural and sustainable alternatives, combined with adequate storage conditions to protect cultivars from harmful agents. This review systematizes the state-of-the-art DPA application on several fresh cultivars, such as apples, pears, and vegetables (potatoes, spinach, etc.), as well as the possible mechanisms of the action and effects of DPA, emphasizing its antioxidant properties. Alternative methods to DPA are also discussed, as well as respective effects and limitations. Recent research on scald development molecular pathways are highlighted to open new non-chemical strategies opportunities. This appraisal shows that most of the current solutions have not lead to satisfactory commercial results; thus, further research aimed to understand the mechanisms underlying postharvest disorders and to design sustainable and safe solutions to improve horticultural products storage is needed.
- The impact of plant-based coatings in “ROCHA” pear preservation during cold storage: a metabolomic approachPublication . Fonseca, Alexandre M. A.; Dias, Cindy; Amaro, Ana L.; Isidoro, Nélson; Pintado, Manuela; Silvestre, Armando J. D.; Rocha, Sílvia M.Although new storage technologies have been emerging in recent years, preservation of pear (Pyrus communis L.) remains a challenge for suppliers. Maintenance of desired organoleptic properties throughout cold storage using non-chemical strategies has been investigated and the use of edible coatings has shown potential to delay fruit quality deterioration during cold storage. Thus, the objective of this study is to evaluate the impact of pectin coatings including plant extracts, in “Rocha” pear (Pyrus communis L. cv. Rocha) preservation. A four-month pilot scale assay was performed in both dynamic controlled atmosphere (DCA) (−0.5 °C, 0.5% O2, and 0.4% CO2) and normal atmospheric (NA) conditions (2 °C). For each storage condition, the following three coatings were tested: pectin (3% w/v) (PCT), pectin (3% w/v) + strawberry tree leaves extract (9.5 mg/mL) (CT1), and pectin (3% w/v) + apple pomace extract (16 mg/mL) (CT2). Volatile compounds, potentially related to aroma or ripening status of “Rocha” pear, were monitored alongside with conjugated trienols (CTs) and maturity parameters. The combination of DCA conditions and the application of pectin coatings were able to reduce the release of Rocha pear volatiles associated with ripening status, (particularly esters and sesquiterpenes), as well as reduce CTs, which could contribute to the preservation of Rocha pear for longer periods.