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- The effect of essential oils on the post-harvest quality of sweet cherry, Prunus avium L. cv. SummitPublication . Silva, Kevin; Lamas, Sandra; Ferreiro, Nuno Manuel; Ramalhosa, Elsa; Pereira, J.A.; Rodrigues, NunoSweet cherry (Prunus avium L.) is a very well appreciated and consumed fruit, not only for its sweetness, smell, and fruity taste, but also for its visual attractiveness and recognized nutritional value. Sweet cherries are rich in sugars, phenolics, anthocyanins and melatonin. Its consumption prevents the appearance of vascular diseases, cancer, diabetes and inflammatory diseases. In 2019, the national production was 19130 ton. The production is concentrated in two producing regions, one in the interior centre of the country, Fundão region, and the other in the north interior land, in the regions of Lamego-Resende and Alfandega da Fé. Sweet cherry is a non-climacteric fruit with a reduced post-harvest period that requires low temperature around 0.5 °C and relative humidity around 90%. The fruits are generally consumed in fresh as raw fruit. Nevertheless, the modern style of life looks for practical ways to present the fruits, generally in individual packages. Furthermore, in some cases, in the local market, there are no availability of cold storage, being the fruits preserved at room temperature, causing high percentages of decay in few days. Essential oils are recognized as possessing antioxidant and antimicrobial activities and could be used as food preservative among other applications in food industry. In this context, with this work we intended to study the effect of two essential oils, from sweet orange (Citrus sinensis cv. Late) and lavender (Lavanda angustifolia Mill.), on the post-harvest quality of sweet cherry, P. avium Cv. Summit. Plastic individual packages with 100 g of fruits were prepared, and in the top of the recipient, a filter paper of 1 cm2 of diameter was put. In each paper filter, 10 microliters of essential oil were added, being the control treated with distilled water. The packages were stored at room temperature. On each day, during seven consecutive days, the following parameters were evaluated for each treatment: colour, rupture force, elasticity, loss of weight, total soluble solids (TSS), titratable acidity, pH, and sensory evaluation. For each treatment and each day, three independent assays were made. In general, the results indicated that the treatments caused different effects on the cherries. The colour of the cherries changed along storage, acquiring brownish colour after 7 days. This effect was mainly observed in the fruits of the control and those submitted to the lavender essential oil. It was also with this essential oil, that the highest loss on the texture, measured by the rupture force, was observed. When comparing the rupture force measured after 7 days with the beginning, a decrease of 39, 53 and 36% were determined for the control (without essential oil), lavender and orange essential oils, respectively. Similar trend was observed for elasticity, suggesting a softening effect by the lavender essential oil. Almost all situations, the loss of weight increased after 4 days. Concerning the TSS, the values oscillated along the storage time, without a definite trend, ranging the means between 11.3 and 13.4 ºBrix. The titratable acidity was not affected by the treatments and the storage time, varying between 0.4 and 0.6 g malic acid/100 g fresh weight. Similar trend was observed for the pH (3.5 to 4.1). Concerning the sensory evaluation, the essential oils were detected by the panellists as a strange odour; however, the orange essential oil was more acceptable than the lavender. Furthermore, after 7 days, the damage intensity was higher in the control and lavender essential oil. In conclusion, the present work indicated that after four days at room temperature, the quality of the cherries was quite affected; however, the orange essential oil seems to delay these effects.
- FTIR-chemometric analytical methodology as a tool for clustering oils from centenarian olive trees grown in the Côa Valley regionPublication . Pascoal-Ferreira, P.; Peres, António M.; Silva, Kevin; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Pereira, J.A.; Baptista, Paula; Rodrigues, NunoThe centenarian olive trees are part of the historical and cultural heritage of the Côa Valley region where a significant number of these specimens can be found. They have high importance in olive grove heritage; however, their genetic and phenotypic diversity is still poorly studied. The identification of olive tree varieties is not an easy task, being required a morphological characterisation complemented with genetics, making this identification a time-consuming and expensive procedure. Recently, Fourier Transform Infrared (FTIR) spectroscopy start to be widely used in several studies in the food field, becoming a powerful analytical tool for the analysis of edible oils and fats1. This technique has numerous advantages, allowing a fast and non-destructive analysis, and requiring minimal sample preparation. In this context, FTIR has been applied to classify and identify different fats2, detection of virgin olive oils adulteration3, determination of trans fatty acids4 and evaluation of oil mixtures' composition in foods5, all this based on the spectral profiles 6. Considering that there is a great diversity of centenarian olive trees in which the varieties are unknown, the objective of this work was to use the FTIR technique to identify groups of olive oils with similar chemical characteristics, thus reducing the time and required amount of samples for analysis. Therefore, FTIR was applied to 99 olive oils from centenarian olive trees in the Côa Valley region. FTIR analysis was carried out using an MB300 FTIR from ABB (Zurich, Switzerland) operating in attenuated total reflectance (ATR) mode using a horizontal cell equipped with a diamond crystal. The spectra acquisition was done using 32 scans/min at a resolution of 4 cm-1, being the reading range comprised between 4000 and 500 cm-1. Spectra were acquired and treated using the software Horizon MB version 3.4. The background was acquired every two consecutive assays. Finally, raw transmittance data (in %) of the different olive oils were used for the statistical analysis. A hierarchical clustering dendogram was applied to evaluate the possibility of grouping the 99 olive oils studied according to the full FTIR spectra by computing the distance (dissimilarity) among the olive oils, using the Euclidean distance Ward method for matrix computation. The dendogram (Figure 1) allowed identifying dissimilarities based on the olive oils’ FTIR spectra, enabling to establish 4 main clusters, for a 2nd node cut establishing responding to a distance around 35. Since FTIR spectroscopy is sensitive to different aspects including the olive variety and considering that all the olive oils were extracted under similar conditions and from olives harvested in the same geographical regions, the observed variations can be tentatively attributed to the olive variety or to a similarity of the oils’ chemical composition. The clustering analysis allowed partitioning a large dataset of olive oils into smaller groups based on similar spectra characteristics, enabling the future practical and feasible evaluation of selected oils belonging to each of the 4 established clusters, avoiding the need to evaluate each one of the 99 olive oils.
- The use of electronic nose as alternative non-destructive technique to discriminate flavored and unflavored olive oilsPublication . Rodrigues, Nuno; Silva, Kevin; Veloso, Ana C.A.; Pereira, J.A.; Peres, António M.Cv. Arbequina extra virgin olive oils (EVOO) were flavored with cinnamon, garlic, and rosemary and characterized. Although flavoring significantly affected the physicochemical quality parameters, all oils fulfilled the legal thresholds for EVOO classification. Flavoring increased (20 to 40%) the total phenolic contents, whereas oxidative stability was dependent on the flavoring agent (a slight increase for rosemary and a decrease for cinnamon and garlic). Flavoring also had a significant impact on the sensory profiles. Unflavored oils, cinnamon, and garlic flavored oils had a fruity-ripe sensation while rosemary flavored oils were fruity-green oils. Fruit-related sensations, perceived in unflavored oils, disappeared with flavoring. Flavoring decreased the sweetness, enhanced the bitterness, and did not influence the pungency of the oils. According to the EU regulations, flavored oils cannot be commercialized as EVOO. Thus, to guarantee the legal labelling requirement and to meet the expectations of the market-specific consumers for differentiated olive oils, a lab-made electronic nose was applied. The device successfully discriminated unflavored from flavored oils and identified the type of flavoring agent (90 ± 10% of correct classifications for the repeated K-fold cross-validation method). Thus, the electronic nose could be used as a practical non-destructive preliminary classification tool for recognizing olive oils’ flavoring practice.
- Aplicação de óleos essenciais na conservação de cerejas cv. SummitPublication . Lamas, Sandra; Ferreiro, Nuno Manuel; Silva, Kevin; Ramalhosa, Elsa; Pereira, J.A.; Rodrigues, NunoA cereja (Prunus avium L.) é um fruto com teores elevados em açúcares, compostos fenólicos, antocianina, etc. Em Portugal, a produção está maioritariamente concentrada nas regiões do Fundão, Resende e Alfandega da Fé. Contudo, o fruto é muito perecível, e necessita de ser conservado a baixas temperaturas. A utilização de óleos essenciais (OE), pela sua reconhecida ação antimicrobiana, tem sido proposta como agentes capazes de aumentar o período de pós-colheita de frutos. Nesse sentido, este trabalho teve como objetivo estudar o efeito da aplicação de 2 OE, de laranja (Citrus sinesis cv. Late) e de lavanda (Lavanda angustifolia Mill), em pós-colheita de cereja Cv. Summit. Para tal, foram colocadas 100g de cerejas em caixas de plástico individuais, nas quais na parte superior se colocou um papel de filtro de 1 cm2 humedecido com 10 μl de OE. As cerejas foram armazenadas sob refrigeração (5 ºC) e a cada 5 dias, durante 30 dias, foi avaliada a qualidade dos frutos (acidez, pH, brix, textura, cor, força de rutura do pedúnculo, número de frutos impróprios para consumo e perdas de massa). Para cada observação, foram avaliadas 3 amostras independentes. Os resultados obtidos demonstraram uma degradação dos parâmetros ao longo do ensaio, verificando, que o tratamento com OE de laranja reduziu, em T30 dias, o número de frutos impróprios para consumo (8,3 % ± 7,2), quando comparado com o controlo (36,6% ± 9,5) e o tratamento com OE de lavanda (37,7 % ± 7,4). Os restantes parâmetros avaliados não apresentaram diferenças significativas entre tratamentos.
- Biocontrol ability and production of volatile organic compounds as a potential mechanism of action of olive endophytes against Colletotrichum acutatumPublication . Sdiri, Yosra; Lopes, Teresa; Rodrigues, Nuno; Silva, Kevin; Rodrigues, Isabel; Pereira, J.A.; Baptista, PaulaOlive anthracnose, mainly caused by Colletotrichum acutatum, is considered a key biotic constraint of the olive crop worldwide. This work aimed to evaluate the ability of the endophytes Aureobasidium pullulans and Sarocladium summerbellii isolated from olive trees to reduce C. acutatum growth and anthracnose symptoms, and to assess A. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences on anthracnose development. Among the endophytes tested, only A. pullulans significantly reduced the incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose in detached fruits, as well as the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and germination (up to 3.5-fold) of C. acutatum in dual culture assays. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans + C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or Tween) led to the identification of 37 VOCs, with alcohols being the most diversified and abundant class. The volatile profile of A. pullulans + C. acutatum revealed qualitative and quantitative differences from the controls and varied over the time course of microbial interactions. The most significant differences among treatments were observed at a maximal reduction in anthracnose development. At this stage, a set of VOCs, particularly Z-3-hexen-1-ol, benzyl alcohol and nonanal, were highly positively correlated with the A. pullulans + C. acutatum treatment, suggesting they play a critical role in anthracnose reduction. 6-Methyl-5-hepten-2-one and 2-nonanone were positively associated with the C. acutatum treatment and thus likely have a role in pathogen infection.
- Compostos voláteis em azeites virgens: caracterização e importância no perfil sensorialPublication . Silva, Kevin; Rodrigues, Nuno; Pereira, J.A.; Ramalhosa, ElsaOs compostos voláteis são determinantes dos atributos sensoriais e da sua perceção por parte do consumidor. Nos azeites, o perfil sensorial, em grande parte relacionado com os compostos voláteis, é um dos aspetos distintivos dos azeites de elevada qualidade. No presente trabalho dão-se a conhecer os principais compostos voláteis presentes em azeites e o seu papel no perfil sensória. Adicionalmente, descreve--se uma das principais vias da formação destes compostos, a via da lipoxigenase, e referem-se os trabalhos realizados até ao momento e em curso em Portugal ao nível do perfil volátil de azeites.
- Caracterização dos azeites do vale do Douro: estudo da fração volátilPublication . Silva, Kevin; Ramalhosa, Elsa; Rodrigues, NunoA oliveira é uma cultura que se encontra distribuída um pouco por toda a região do Douro. Até há poucos anos, esta cultura não tinha muita importância económica para a região. Contudo, nos últimos anos a procura pelos seus azeites diferenciados tem aumentado. Dessa forma, é essencial caracterizar os azeites produzidos nesta região de modo a valorizá-los. Os compostos voláteis estão associados aos aromas dos azeites, sendo estes um dos principais responsáveis pela sua aceitação por parte dos consumidores. Assim sendo, o trabalho realizado teve como objetivo caracterizar o perfil sensorial e o perfil em compostos voláteis dos azeites produzidos na região do Douro. Foram colhidas 135 amostras, as quais foram analisadas em termos olfativos e gustativos, e em termos dos compostos voláteis presentes avaliados por Headspace Microextração em Fase Sólida - Cromatografia Gasosa/Espectrometria de Massa (HS/SPME - GC/MS). De entre as amostras recolhidas, 78 apresentavam defeitos sensoriais, maioritariamente “tulha/borra” e “mofo/húmido/terra”. Os azeites sensorialmente considerados virgem extra foram identificados na sua maioria (aproximadamente 64%) como frutados maduros. De entre as sensações olfativas e gustativas, destacaram-se os atributos de frutos secos, tomate, maçã, rama de tomateiro, banana e alfazema. Em relação aos compostos voláteis, destacaram-se em todas as amostras os seguintes compostos: (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol acetato, 1-hexanol e 2-metil-4-pentanal. Não foi possível separar os azeites por concelhos ou sub-regiões tendo em conta os resultados obtidos na análise sensorial, tendo as amostras sido classificadas em quatro grupos que apresentaram perfis voláteis distintos. Os compostos voláteis comuns a todas as amostras foram ainda correlacionados com os atributos sensoriais, tendo sido possível identificar quatro atributos característicos dos azeites do Douro, designadamente os atributos a frutos secos, banana, rosmaninho e alfazema. Em conclusão, o estudo da fração volátil dos azeites desta região, bem como da sua relação com os atributos sensoriais são essenciais para garantir a genuinidade e identidade destes azeites com vista à sua futura valorização.
- Characterisation of olive oils from the Douro Valley, Portugal: study of the volatile fraction and its relationship with sensory characteristicsPublication . Silva, Kevin; Rodrigues, Nuno; Pereira, J.A.; Ramalhosa, ElsaIn recent years, the demand for olive oils from the Douro region (Portugal) has increased in line with wine. Thus, it is essential to characterise these olive oils to evaluate them. Therefore, this work describes the sensory and volatile profiles of olive oils produced in the Douro region. These were mainly identified as ripe fruity. Among the olfactory and gustatory sensations, the attributes of dried fruits, tomato, apple, tomato leaves, banana, and lavender stood out. Regarding volatile compounds, the following were detected in all samples: (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, (Z)-3-hexen-1-ol acetate, 1-hexanol, and 2-methyl-4-pentanal. Moreover, it was impossible to separate the olive oils by sub-regions. In conclusion, studying the volatile fraction and their relationship with sensory attributes are essential to guarantee the genuineness and identity of these olive oils with a view to their future appreciation.
- Compostos voláteis maioritários responsáveis pelos aromas dos azeites da região do DouroPublication . Silva, Kevin; Rodrigues, Nuno; Pereira, J.A.; Ramalhosa, ElsaOs compostos voláteis têm como principal origem uma cadeia de reações enzimáticas, denominada via da lipoxigenase (LOX). Os compostos sintetizados pela LOX, principalmente aldeídos, álcoois e ésteres, são produzidos na sua grande maioria na moenda da azeitona, quando a ruptura da película permite o contacto das enzimas com a polpa das azeitonas. No entanto, o perfil em compostos voláteis pode ser influenciado ao longo de todo o processo até à obtenção do azeite e consequente armazenamento, tanto por fatores agronómicos, como pelas condições de extração e armazenamento do azeite. Os compostos voláteis são os responsáveis pelos aromas dos azeites. Os compostos com origem na LOX estão associados a aromas agradáveis, enquanto compostos com origem nas vias secundárias, como atividade enzimática de fungos, fermentações e processos oxidativos, estão associados a defeitos sensoriais (Kalua et al., 2007).Os azeites da região do Douro têm ganho interesse por parte dos consumidores por se diferenciarem sensorialmente. No entanto, ainda não foram realizados estudos com vista a determinar o seu perfil em compostos voláteis. Desse modo, no presente trabalho pretendeu-se identificar os compostos maioritários responsáveis pelos aromas dos azeites do Douro.
- FTIR-chemometric analytical methodology as a tool for clustering oils from centenarian olive trees grown in the Côa Valley regionPublication . Pascoal-Ferreira, P.; Peres, António M.; Silva, Kevin; Santamaria-Echart, Arantzazu; Barreiro, M.F.; Pereira, J.A.; Baptista, Paula; Rodrigues, NunoThe centenarian olive trees are part of the historical and cultural heritage of the Côa Valley region where a significant number of these specimens can be found. They have high importance in olive grove heritage; however, their genetic and phenotypic diversity is still poorly studied. Recently, Fourier Transform Infrared (FTIR) spectroscopy start to be widely used in several studies in the food field, becoming a powerful analytical tool for the analysis of edible oils and fats. This technique has numerous advantages, allowing a fast and non-destructive analysis, and requiring minimal sample preparation. In this context, FTIR has been applied to classify and identify different fats, detection of virgin olive oils adulteration, determination of trans fatty acids and evaluation of oil mixtures' composition in foods, all this based on the spectral profiles. Considering that there is a great diversity of centenarian olive trees in which the varieties are unknown, the objective of this work was to use the FTIR technique to identify groups of olive oils with similar chemical characteristics, thus reducing the time and required amount of samples for analysis.