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- Ultrasound assisted coextraction of Cornicabra olives and thyme to obtain flavored olive oilsPublication . Peres, Maria de Fátima; Marques, Madalena Pinho; Mourato, Miguel; Martins, Luísa; Dias, Suzana FerreiraFlavoring olive oils is a new trend in consumer preferences, and different enrichment techniques can be used. Coextraction of olives with a flavoring agent is an option for obtaining a flavored product without the need for further operations. Moreover, ultrasound (US) assisted extraction is an emergent technology able to increase extractability. Combining US and coextraction, it is possible to obtain new products using different types of olives (e.g., cultivar and ripening stage), ingredient(s) with the greatest flavoring and/or bioactive potential, as well as extraction conditions. In the present study, mastic thyme (Thymus mastichina L.) (TM) and lemon thyme (Thymus x citriodorus) (TC) were used for flavoring Cornicabra oils by coextraction. The coextraction trials were performed by (i) thyme addition to the olives during crushing or malaxation and (ii) US application before malaxation. Several parameters were evaluated in the oil: quality criteria parameters, total phenols, fatty acid composition, chlorophyll pigments, phenolic profile and oxidative stability. US application did not change the phenolic profile of Cornicabra olive oils, while the enrichment of olive oils with phenolic compounds or pigments by coextraction was very dependent on the thyme used. TM enrichment showed an improvement of several new phenolic compounds in the oils, while with TC, fewer new phenols were observed. In turn, in the trials with TC, the extraction of chlorophyll pigments was higher, particularly in crushing coprocessing. Moreover, the oils obtained with US and TM added in the mill or in the malaxator showed lower phenol decrease (59%) than oils flavored with TC (76% decrease) or Cornicabra virgin olive oil (80% decrease) over an 8-month storage period. Multivariate data analysis, considering quality parameters, pigments and phenolic contents, showed that flavored oils were mainly grouped by age.
- How the “Olive Oil Polyphenols” health claim depends on anthracnose and olive fly on fruitsPublication . Peres, Maria de Fátima; Gouveia, Cecília; Vitorino, Conceição; Oliveira, Helena; Dias, Suzana FerreiraOlive anthracnose, caused by Colletotrichum fungi, and the olive fruit fly Bactrocera olea are, respectively, the most important fungal disease and pest affecting olive fruits worldwide, leading to detrimental effects on the yield and quality of fruits and olive oil. This study focuses on the content of hydroxytyrosol (HYT) and its derivatives (the “olive oil polyphenols” health claim) in olive oils extracted from fruits of ‘Galega Vulgar’ and ‘Cobrançosa’ cultivars, naturally affected by olive anthracnose and olive fly. The olives, with different damage levels, were harvested from organic rainfed orchards, located in the center of Portugal, at four harvest times over three years. Galega oils extracted from olives with a higher anthracnose and olive fly incidence showed no conformity for the extra virgin olive oil (EVOO) and virgin olive oil (VOO) categories, presenting high acidity and negative sensory notes accompanied by the disappearance of oleacein. Conversely, no sensory defects were observed in Cobrançosa oils, regardless of disease and pest incidence levels, and quality criteria were still in accordance with the EVOO category. The total HYT and tyrosol (TYR) content (>5 mg/20 g) allows for the use of the “olive oil polyphenols” health claim on the label of all the analyzed Cobrançosa olive oils.
- Bioactive compounds of portuguese virgin olive oils discriminate cultivar and ripening stagePublication . Peres, Maria de Fátima; Martins, Luísa; Mourato, Miguel; Vitorino, Conceição; Dias, Suzana FerreiraThe presence of different bioactive compounds in virgin olive oil affects its nutritional, oxidative and sensorial properties. Phenolic compounds are olive endogenous bioactive compounds highly susceptible to degradation. Olive endogenous oxidoreductases, mainly polyphenol oxidases (PPO) and peroxidases (POD), may play an important role on the profile of bioactive compounds in olive oil by promoting oxidation of phenolic compounds. The aim of this study was to evaluate if changes on PPO and POD activities in olive fruits from two Portuguese cultivars (Olea europaea, cv ‘Cobrançosa’ and cv ‘Galega Vulgar’) are related with the composition of their olive oils, especially phenolic compounds. Pattern recognition techniques [principal component analysis (PCA), cluster analysis(CA), and discriminant analysis (DA)] were used for multivariate data analysis. Olive oils characterized by their FA composition were grouped by cultivar. When olive oils were characterized by their phenolic composition, green pigments, and enzymatic activities in fruits, they could be discriminated by olive ripening stage. Along ripening, PPO activity was only detected in the fruit mesocarp of both cultivars and POD activity was mainly detected in the seeds. The POD activity, as well as vanillin and gamma-tocopherol contents in olive oil increased with the ripening index. Conversely, higher PPO activity in fruits at early ripening stages together with higher levels of total phenols, green pigments, betatocopherol, hydroxytyrosol and p-coumaric acid in olive oils were observed. The ripening stage of fruits showed to be a key factor on the amount and profile of bioactive compounds of olive oil.
- Influence of enzymes and technology on virgin olive oil compositionPublication . Peres, Maria de Fátima; Martins, Luísa; Dias, Suzana FerreiraThis work aims at presenting the state-of-the-art about the influence of the activity of olive endogenous enzymes, as well as of the application of adjuvants in olive oil technology, discussing their influence on the composition of virgin olive oil, especially in phenols and volatile compounds.
- Ácidos fenólicos, alcoóis fenólicos secoiridoides, flavonoides e tocoferóis em azeites virgensPublication . Peres, Maria de Fátima; Martins, Luísa; Mourato, Miguel; Vitorino, Conceição; Dias, Suzana FerreiraAs características excepcionais do azeite virgem extra devem-se não só ao seu perfil em ácidos gordos mas também à presença de compostos de natureza fenólica que contribuem para o seu valor nutricional. Os estudos mais actuais evidenciam diversos benefícios para a saúde destes compostos, o que levou a União Europeia a aprovar uma alegação nutricional em 2012 sobre “polifenóis do azeite”. Os compostos fenólicos do azeite virgem apresentam também propriedades sensoriais, nomeadamente pela sua contribuição para o sabor amargo. Além disso, contribuem para a estabilidade oxidativa do azeite, pelo que, quando presentes em elevada quantidade, aumentam o seu tempo de vida. A sua avaliação nos azeites pode vir a ter uma importância fundamental para a diferenciação de azeites de elevada qualidade nutricional e sensorial. No presente trabalho, estudaram-se os compostos fenólicos de natureza hidrofílica e lipofílica, em azeites provenientes das cultivares ‘Cobrançosa’ e ‘Galega Vulgar’. Por HPLC-FLD, foram quantificados alfa, beta e gama tocoferóis (fenóis lipofílicos). Nos azeites de ambas as cultivares, os teores de alfa-tocoferol foram sempre superiores a 200 mg kg-1, apresentando os azeites ‘Galega Vulgar’ maiores teores de gama tocoferol. Relativamente ao perfil em compostos fenólicos (hidrofílicos), avaliados por HPLCDAD, foi possível quantificar os teores de hidroxitirosol, tirosol, ácido vanílico, vanilina, ácido o-cumárico, luteolina e apigenina. Identificou-se ainda a presença de 3,4-DHPEA-EDA, p-HPEA-EDA, 3,4-DHPEA-EA e p-HPEA-EA. O composto fenólico maioritário nos azeites foi o 3,4-DHPEA-EDA, representando em alguns azeites mais de 50 % do total de compostos fenólicos. Foram encontrados baixos teores de hidroxitirosol e tirosol, como é expectável em azeites recentemente extraídos. Os azeites ‘Cobrançosa’ apresentaram, em geral, teores mais elevados de flavonóides.
- Co-processed olive oils with Thymus mastichina L.: New product optimizationPublication . Peres, Maria de Fátima; Roldão, Marta; Mourato, Miguel; Martins, Luísa; Dias, Suzana FerreiraOlive co-processing consists of the addition of ingredients either in the mill or in the malaxator. This technique allows selecting the type of olives, the ingredients with the greatest flavoring and bioactive potential, and the technological extraction conditions. A new product—a gourmet flavored oil—was developed by co-processing olives with Thymus mastichina L. The trials were performed using overripe fruits with low aroma potential (cv. ‘Galega Vulgar’; ripening index 6.4). Experimental conditions were dictated by a central composite rotatable design (CCRD) as a function of thyme (0.4−4.6%, w/w) and water (8.3−19.7%, w/w) contents used in malaxation. A flavored oil was also obtained by adding 2.5% thyme during milling, followed by 14% water addition in the malaxator (central point conditions of CCRD). The chemical characterization of the raw materials, as well as the analysis of the flavored and unflavored oils, were performed (chemical quality criteria, sensory analysis, major fatty acid composition, and phenolic compounds). Considering chemical quality criteria, the flavored oils have the characteristics of “Virgin Olive Oil” (VOO), but they cannot have this classification due to legislation issues. Flavored oils obtained under optimized co-processing conditions (thyme concentrations > 3.5−4.0% and water contents varying from 14 to 18%) presented higher phenolic contents and biologic value than the non-flavored VOO. In flavored oils, thyme flavor was detected with high intensity, while the defect of “wet wood”, perceived in VOO, was not detected. The flavored oil, obtained by T. mastichina addition in the mill, showed higher oxidative stability (19.03 h) than the VOO and the co-processed oil with thyme addition in the malaxator (14.07 h), even after six-month storage in the dark (16.6 vs. 10.3 h).
- Development of Cobrançosa "functional olive oils" by co-processing techniquesPublication . Marques, Madalena Pinho; Dias, Suzana Ferreira; Gouveia, Cecília; Vitorino, Conceição; Mourato, Miguel; Martins, Luísa; Peres, Maria de FátimaThe aim of this work was to develop "functional olive oils" by co-processing techniques of ‘Cobrançosa’ olives with the addition of Thymus citriodorus (TL, lemon thyme) and T. mastichina L. (TM) from organic agriculture. The “functional olive oils” were prepared by: (i) thyme addition to the olives during the unit operations of crushing or malaxation, and (ii) implementation of ultrasound before the malaxation of the olive paste.
- Avaliação da maturação em azeitona ‘Cobrançosa’ e ‘Galega Vulgar’ com recurso a diferentes metodologias baseadas na cor dos frutosPublication . Peres, Maria de Fátima; Ramos, António Santos; Vitorino, Conceição; Gouveia, Cecília; Dias, Suzana Ferreira; Martins, LuísaNo presente trabalho estudaram-se três métodos de avaliação do estado de Maturação da azeitona, baseados na coloração dos frutos das cultivares ‘Cobrançosa’ e ‘Galega Vulgar’ em estados precoces de maturação, bem como a sua relação com a acumulação de gordura. Os métodos estudados foram: IM – índice de maturação de Jaén (com 8 grupos de cor); IMS – índice de maturação simplificado com apenas três classes de cor; CI – índice de cor (Colour Index) utilizando o Sistema CIE de cor L*a*b*. Os resultados obtidos revelaram que os índices de maturação baseados na cor dos frutos são úteis para caracterizar a evolução do teor em gordura durante a maturação da azeitona. O método simplificado apresentou uma elevada correlação com o índice de Jaén, sendo bastante mais rápido e de mais fácil utilização pelo olivicultor.
- Ensaios experimentais para avaliar a utilização de adjuvantes tecnológicos na extracção de azeite virgemPublication . Peres, Maria de Fátima; Martins, Luísa; Vitorino, Conceição; Gouveia, Cecília; Dias, Suzana FerreiraNo processamento de produtos vegetais, a utilização de adjuvantes tecnológicos para melhorar o rendimento e a qualidade dos alimentos tem uma vasta aplicação industrial. No entanto, no processo de extracção de azeite virgem a utilização de adjuvantes tecnológicos tem ainda uma utilização muito residual. Por sua vez, tal aplicação pode ter uma importância determinante no aumento do rendimento industrial, nomeadamente quando no lagar se apresentam azeitonas com características de pastas de difícil extração. No presente trabalho apresentam-se alguns ensaios realizados no lagar experimental do Laboratório de Tecnologia Alimentar da ESACB, aplicando diferentes sistemas enzimáticos e microtalco natural na operação de termobatedura. Os ensaios realizaram-se com azeitona das cultivares ‘Galega Vulgar’ e ‘Cobrançosa’ colhidas com índices de maturação bem definidos. A extracção de azeite foi efectuada em equipamento constituído por moinho de martelos (3000 rpm), termobatedeira (50 rpm) e centrifugadora (3500 rpm). Apresentam-se ainda resultados de optimização das condições de operação do equipamento utilizando um delineamento Placket-Burman para seleccionar as variáveis significativas, seguido por um delineamento descrito por uma matriz central compósita rotativa (CCRD) em função dessas variáveis. Avaliaram-se o rendimento e o índice de extractabilidade da azeitona; no azeite, avaliaram-se os critérios de qualidade, os fenóis totais e os pigmentos clorofilinos. As respostas relacionadas com o rendimento de extracção podem ser descritas por modelos polinomiais de segundo grau com um elevado ajuste aos dados experimentais (r> 0,8). Em todos os ensaios efectuados com adição de adjuvantes, verificou-se um aumento no rendimento e consequentemente do índice de extractabilidade, relativamente aos ensaios sem qualquer adjuvante de extracção. Os ensaios permitem concluir que a adição de adjuvantes tecnológicos não provocou quaisquer alterações nos teores de compostos fenólicos, nos pigmentos clorofilinos nem nos parâmetros de qualidade dos azeites obtidos.
- Optimization of autohydrolysis of olive pomaces to obtain bioactive oligosaccharides: The effect of cultivar and fruit ripeningPublication . Freitas, Laura; Simões, Rita; Miranda, Isabel; Peres, Maria de Fátima.; Dias, Suzana FerreiraThe valorisation of agro-industrial residues presents a challenge in obtaining economically sustainable and environmentally friendly industrial processes. Olive pomace is a by-product generated in large quantities, from olive oil extraction. This residue mostly consists of lignocellulosic materials. The aim of this study was to evaluate the potential use of extracted olive pomaces (EOP) obtained from olives with different ripening indexes (RI) and from different cultivars (Cobrançosa; RI = 2.5; 3.3 and 4.7; and Galega Vulgar; RI = 1.8; 2.9 and 4.8), to produce bioactive oligosaccharides from hemicelluloses by autohydrolysis. The hydrothermal treatment conditions were optimized by Response Surface Methodology, following a central composite rotatable design (CCRD), as a function of temperature (T: 142–198 °C) and time (t: 48–132 min), corresponding to severity factor (SF) values from 3.2 to 4.9. For all pomace samples, soluble sugar production was described by concave surfaces as a function of temperature and time. Autohydrolysis with SF equal or higher than 4.0 produced higher sugar yields, with maximum values around 180 g glucose equivalent/kg EOP for SF of 4.7 (190 °C/120 min) or 4.9 (198 °C/90 min). These values were similar for both cultivars and were not dependent on the ripening stage of the olives. Maximum oligosaccharide (OS) yields of 98% were obtained by autohydrolysis with SF of 4.0. The increase in SF to 4.9 resulted in a decrease in OS yield to 86–92%, due to the release of monomeric sugars. The monosaccharides were mostly xylose (55.8–67.7% in Galega; 50.4–69.0% in Cobrançosa liquid phases), and glucose, galactose, arabinose and rhamnose, in smaller quantities. Therefore, the production of bioactive xylo-oligosaccharides (XOS) from olive pomaces mainly depends on the hydrothermal conditions used.