DETERMINAÇÃO DO MOMENTO ÓPTIMO DE COLHEITA DAS CULTIVARES DE OLIVEIRA PERTENCENTES A DENOMINAÇÃO DE ORIGEM PROTEGIDA AZEITE DE TRÁS-OS-MONTES

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Aromatized olive oils: Influence of flavouring in quality, composition, stability, antioxidants, and antiradical potential

Publication . Sousa, Anabela; Casal, Susana; Malheiro, Ricardo; Lamas, Hugo; Bento, Albino; Pereira, J.A.

In the present work different flavourings (garlic, hot chili peppers, laurel, oregano and pepper) commonly used in Mediterranean cuisine were added to olive oils from Cv. Cobrançosa. Flavouring influence in olive oils quality, fatty acids profile, tocopherols and tocotrienols composition, antiradical activity, total phenols content and oxidative stability were evaluated. Garlic addition induced an increase in free acidity values (from 0.6 to 0.8%), but the remaining quality indices weren't negatively affected. Fatty acids profile changed but values remained under the limits of extra-virgin olive oils. Olive oils were nutritionally enriched due to the increase in vitamin E, mainly in oils flavoured with hot chili pepper (198.6 mg/kg). Antioxidant properties were influenced as well. Total phenols content decreased in all flavoured olive oils (control with 345.7 mg CAE/kg; oregano 293.8 mg CAE/kg) but the capability to counteract oxidation was generally improved (control with 9.4 h and oregano with 10.4 h). The addition of flavouring influenced quality, composition and olive oils characteristics being possible to separate them according to the flavouring used by applying chemometrics.

2015Journal article

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Optimal harvesting period for cvs. Madural and Verdeal Transmontana, based on antioxidant potential and phenolic composition of olives

Publication . Sousa, Anabela; Malheiro, Ricardo; Casal, Susana; Bento, Albino; Pereira, J.A.

In the present study we propose to determine an approximate optimum harvesting period for table olives and olive oil of two Portuguese olive cultivars (Madural and Verdeal Transmontana) based on phenolic modifications (HPLC/DAD) and antioxidant activity (scavenging capacity on 2,2-diphenyl-1- picrylhydrazyl and reducing power). Samples were collected from almost edibility to slightly overmature. The sum of polyphenols, as well as its most abundant components oleuropein and hydroxytyrosol, decreased during this maturation period, more intensively in Madural than Verdeal Transmontana. In their green stages an antioxidant potential loss was gradually observed in both olive cultivars, while in the latter purple-black phases a slight increase in the antioxidant activity was observed. Both phenolic profile and antioxidant activity were highly correlated with the maturation process. A principal component analysis showed the particular effect of maturation in both olive cultivars. Based on the acquired knowledge we can advance that, for these cultivars and geographical region, olives harvest for table olives, traditionally collected sooner, can be performed in the middle of September. For olive oil harvesting can occur in the first days of November, giving priority to cv. Madural rather than Verdeal Transmontana, in order to enhance the bioactivity, phenolic composition and stability of olive oils.

2015Journal article

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A maturação como fator determinante na atividade antioxidante e composição fenólica em frutos da Cv. Cobrançosa

Publication . Sousa, Anabela; Malheiro, Ricardo; Casal, Susana; Bento, Albino; Pereira, J.A.

O grau de maturação é um dos principais fatores que influi na composição e bioactividade de azeitonas de mesa, bem como na obtenção de azeites de qualidade. Neste sentido, no presente trabalho foram estudadas as alterações sofridas por frutos da Cv. Cobrançosa ao nível da sua actividade antioxidante e composição fenólica ao longo da maturação do fruto, entre finais de setembro e novembro. A atividade antioxidante foi avaliada pelo efeito bloqueador de radicais livres de DPPH e pelo método do poder redutor e o perfil fenólico foi avaliado por cromatografia líquida de alta resolução com um detector de díodos (HPLC/DAD). Foram identificados e quantificados sete compostos fenólicos que variaram ao longo da maturação do fruto. A oleuropeína foi o composto mais abundante nas fases iniciais, reduzindo o seu teor drasticamente ao longo da maturação até ao seu desaparecimento completo. O hidroxitirosol foi o composto maioritário nas fases de maturação intermédias e avançadas. O teor total em compostos fenólicos variou entre 33856 mg/kg e 960 mg/kg, respectivamente, da primeira para à última data de amostragem. O potencial poder redutor dos frutos da Cv. Cobrançosa foi reduzindo ao longo da maturação, facto que se revelou estar relacionado com a composição fenólica. A aplicação de técnicas quimiométricas ajudou a entender o efeito da maturação ao nível da actividade antioxidante e perfil fenólico. Os dados obtidos poderão também auxiliar na determinação de um momento óptimo de colheita para a Cv. Cobrançosa, de modo a melhorar as propriedades e composição tanto de azeite como de azeitonas de mesa.

2014Conference object

Open access

Antioxidant activity and phenolic composition of Cv. Cobrançosa olives affected through the maturation process

Publication . Sousa, Anabela; Malheiro, Ricardo; Casal, Susana; Bento, Albino; Pereira, J.A.

Maturation stage is a critical feature to obtain high quality olive products, with maximized bioactivity. In this study, phenolic composition and antioxidant activity of Cv. Cobrançosa through the maturation process were evaluated.The phenolic profile was assessed by HPLC/ DAD, and antioxidant activity was studied through its reducing power and free-radical scavenging activity. Total phenols varied from 34 to 1 g/kg, respectively, in the first and last sampling dates. Oleuropein, the main phenolic in the first stages of maturation, decreased drastically during ripening. At intermediate and high maturation stages hydroxytyrosol was the predominant phenol. Globally, the reducing capacity of Cv. Cobrançosa olive fruits decreased during the maturation process but its radical scavenging activity was only slightly altered. A principal components analysis corroborated the characteristic phenolic profile and changes experienced by the olive fruit during the maturation process. These results are important to maximize Cv. Cobrançosa olive products’ quality and biological properties.

2014Journal article

Restricted access