A taste sensor device for unmasking admixing of rancid or winey-vinegary olive oil to extra virgin olive oil

Electrochemical sensor devices have gathered great attention in food analysis namely for olive oil evaluation. The adulteration of extra-virgin olive oil with lower-grade olive oil is a common worldwide fraudulent practice, which detection is a challenging task. The potentiometric fingerprints recorded by lipid polymeric sensor membranes of an electronic tongue, together with linear discriminant analysis and simulated annealing meta-heuristic algorithm, enabled the detection of extra-virgin olive oil adulterated with olive oil for which an intense sensory defect could be perceived, specifically rancid or winey-vinegary negative sensations. The homemade designed taste device allowed the identification of admixing of extra-virgin olive oil with more than 2.5% or 5% of rancid or winey-vinegary olive oil, respectively. Predictive mean sensitivities of 84±4% or 92±4% and specificities of 79±6% or 93±3% were obtained for rancid or winey-vinegary adulterations, respectively, regarding an internal-validation procedure based on a repeated K-fold cross-validation variant (4 folds×10 repeats, ensuring that the dataset was forty times randomly split into 4 folds, leaving 25% of the data for validation purposes). This performance was satisfactory since, according to the legal physicochemical and sensory analysis, the intentionally adulterated olive oil with percentages of 2.510%, could still be commercialized as virgin olive oil. It could also be concluded that at a 5% significance level, the trained panelists could not distinguish extra-virgin olive oil samples from those adulterated with 2.5% of rancid olive oil or up to 5% of winey-vinegary olive oil. Thus, the electronic tongue proposed in this study can be foreseen as a practical and powerful tool to detect this kind of worldwide common fraudulent practice of high quality olive oil.This work was financially supported by Project POCI-01–0145FEDER-006984 – Associate Laboratory LSRE-LCM, Project UID/QUI/ 00616/2013 – CQ-VR, Project UID/BIO/04469/2013 – CEB and strategic project PEst-OE/AGR/UI0690/2014 – CIMO all funded by FEDER - Fundo Europeu de Desenvolvimento Regional through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI) – and by national funds through FCT - Fundação para a Ciência e a Tecnologia, Portugal. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014). Souheib Oueslati is also grateful for the support of the Tunisian Ministry of Agriculture.info:eu-repo/semantics/publishedVersio

Effect of malaxation temperature on the physicochemical and sensory quality of cv. Cobrançosa olive oil and its evaluation using an electronic tongue

Olive oil is consumed worldwide due to its appreciated sensory attributes and health benefits, which are related with its fatty acid profile and richness in phenolic compounds that support a health claim concerning olive oil protective effects on blood lipids. However, to ensure that oils possess a rich phenolic content, the extraction conditions can be optimised. Therefore, the effects of malaxation temperature (22, 28 and 34 ºC) on the physicochemical and sensory characteristics of cv. Cobrançosa olive oils were evaluated. The oils extracted at 22 ºC had an overall better physicochemical quality (higher total phenols content, greater oxidative stability, lower free acidity and oxidation markers) and more intense positive sensory sensations (higher bitterness and pungency). Additionally, this study showed that a potentiometric electronic tongue could be used to discriminate oils taking into account the effect of malaxation temperature on the overall physicochemical and sensory scores (all samples correctly classified for leave-one-out cross-validation) with a predictive classification similar to that achieved by trained panellists. This finding strengthens the hypothesis that this device could be used as a complementary/alternative taste tool for assessing the impact of the extraction conditions on the oils physicochemical and sensory characteristics.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020), to CEB (UIDB/04469/2020), to REQUIMTE-LAQV (UIDB/50006/2020) units and to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte. ´Itala M.G. Marx also acknowledges the PhD research grant (SFRH/BD/137283/2018) provided by FCT. Nuno Rodrigues thanks to National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Application of electrochemical sensors as an alternative tool for perfume evaluation

Mestrado de dupla diplomação com a Université Libre de TunisThe capability to discriminate perfumes based on their specific aroma profiles is of utmost relevance for the perfume industry considering that, the identification of more than three aromas is a very difficult task even for a trained human nose. Currently, no analytical tool can completely substitute the human nose for aroma evaluation. Also, no analytical system can fully mimic the human perception, being the recognition of perfume aroma patterns usually carried out by gas chromatography coupled with olfactometry or sniffing techniques or even by applying electronic noses, although it still is a difficult analytical task. In this work, the possibility of applying a potentiometric electronic tongue as an analytical sensors tool for perfume analysis, was evaluated for the first time. In fact, the perfume aroma pattern will depend on the composition of the liquid perfume phase and on the diffusion properties of the volatile components, making the proposed strategy feasible from a theoretical point of view. A multi-sensor potentiometric device, comprising a set of 40 lipid sensor membranes with cross-sensitivity, was applied together with chemometric techniques to identify and establish unique chemical perfume fragrances’ fingerprints for discriminating perfumes according to the target consumer (men – women perfumes), the perfume olfactory family (Citric-Aromatic, Floral, Floral-Fruity, Floral-Oriental, Floral-Woody, Woody-Oriental and Woody-Spicy) or the perfume storage time-period (≤ 9 months; 9-24 months; and, ≥ 24 months). Linear discriminant multivariate models were established, based on potentiometric profiles gathered by sub-sets of sensors selected using the simulated annealing algorithm, and allowed correct classification rates of 93-100% (for leave-one-out cross-validation procedure). The satisfactory analytical performance of the electronic tongue demonstrates the versatility of the proposed approach, as a practical device for preliminary perfume classification, which industrial application may be foreseen in a near future, contributing to a green-sustained economic growth of the perfume industry.A capacidade de discriminar perfumes com base em seus perfis de aromas específicos é de extrema relevância para a indústria de perfumes, considerando que a identificação de mais de três aromas é uma tarefa muito difícil, mesmo para um nariz humano treinado. Atualmente, nenhuma ferramenta analítica pode substituir completamente o nariz humano na avaliação do aroma. Além disso, nenhum sistema analítico pode imitar completamente a percepção humana, sendo o reconhecimento de padrões de aroma de perfume geralmente realizados por cromatografia em fase gasosa acoplada a técnicas de olfatometria ou cheirar ou mesmo pela aplicação de narizes eletrónicos, embora ainda seja uma tarefa analítica difícil. Neste trabalho, a possibilidade de aplicar uma língua eletrónica potenciométrica como uma ferramenta analítica de sensores para a análise de perfumes foi avaliada pela primeira vez. De fato, o perfil de aromas do perfume dependerá da composição da fase líquida do perfume e das propriedades de difusão dos componentes voláteis, viabilizando a estratégia proposta do ponto de vista teórico. Um dispositivo potenciométrico de multisensores, com um conjunto de 40 membranas lipídicas com sensibilidade cruzada foi aplicado, em conjunto com técnicas quimiométricas para identificar e estabelecer perfis típicos de fragrâncias químicas para discriminação de perfumes de acordo com o consumidor-alvo (perfumes masculinos - femininos ), a família olfativa do perfume (cítrico-aromático, floral, floral-frutado, floral-oriental, floral-amadeirado, amadeirado-oriental e amadeirado-especiado) ou o período de armazenamento do perfume (≤ 9 meses; 9-24 meses e ≥ 24 meses). Modelos multivariados discriminantes lineares foram estabelecidos, com base em perfis potenciométricos de subconjuntos de sensores selecionados usando o algoritmo de recozimento simulado, e permitiram obter taxas de classificação corretas de 93 a 100% (para a validação cruzada “leave-one-out”). O desempenho analítico satisfatório da língua eletrónica demonstra a versatilidade da abordagem proposta, como um dispositivo prático para a classificação preliminar de perfumes, cuja aplicação industrial pode ser prevista em um futuro próximo, contribuindo para um crescimento económico sustentado da indústria de perfume

Influência do modo de produção, biológico convencional, e do estado de maturação do fruto na composição e qualidade do pimento, Capsicum annuum L.

O pimento, Capsicum annuum L., é um fruto muito consumido e apreciado. A sua composição pode ser afetada pelo modo de produção e pelo estado de maturação dos frutos. O presente trabalho teve como objetivo obter informação acerca da produção em modo de produção biológico de pimento (variedade Entinas) na região de Coimbra, e estudar o efeito do modo de produção, produção biológica e integrada/convencional, na composição em minerais, compostos fenólicos, compostos voláteis, atividade antioxidante e caraterísticas de qualidade do pimento. Os resultados indicam que o cultivo do pimento em modo de produção biológico, em cultura de primavera/verão ao ar livre, apre-senta bom desenvolvimento cultural, produtividades na ordem das 28 t.ha-1, e que os frutos são de qualidade. A comparação dos pimentos produzidos em modo de produção biológico e convencional, em diferentes estados de maturação (verde e vermelho), permitiu constatar que os primeiros, independentemente do estado de maturação, apresentaram maiores concentrações de potássio, fósforo, cálcio e cobre, cloro, ferro e enxofre, e os segundos apresentaram concentrações de manganês e zinco superiores. Foram identifica-dos nove compostos fenólicos: ácido cafeico, ácido clorogénico, ácido m-cumárico, ácido o-cumárico, luteolina-7-O-glucósido, miricetina, resveratrol, rutina e quercetina-3-O-rhamnosideo, e 48 compostos voláteis pertencentes a classes distintas. Os pimentos verdes produzidos de forma convencional foram os mais ricos em compostos fenólicos e com maior atividade antioxidante, bem como os que apresentaram maiores teores de com-postos voláteis. Por outro lado, os pimentos produzidos no modo de produção biológico apresentaram melhor qualidade visual e tátil e menor qualidade química quando avaliados por um painel sensorial. Utilizou-se uma língua eletrónica potenciométrica que permitiu discriminar pimentos de acordo com o modo de produção e estado de maturação dos frutos. No presente trabalho os pimentos provenientes do modo de produção convencional apresentaram, no geral, melhor qualidade e melhores caraterísticas químicas.Sweet pepper, Capsicum annuum L., is a widely consumed and appreciated fruit. Its composition can be affected by the production system and ripeness stage of fruits. This work aims to obtain information about pepper (variety Entinas) in organic production in the region of Coimbra, and to study the effect of production system, organic and integrated / conventional production, in its mineral, phenolic and volatile composition, anti-oxidant activity and quality characteristics. The results indicated that the production of sweet pepper in organic production, in spring / summer open-air conditions, presents good cultural development, productivity around 28 t.ha-1, and that the fruits are of good quality. The comparison of peppers produced in organic and conventional production systems, in different ripening stages (green and red), showed that the first ones, regardless of their ripeness, had higher concentrations of potassium, phosphorus, calcium and copper, chlorine, iron and sulphur, and the seconds showed higher concentrations of manganese and zinc. Nine phenolic compounds were identified: caffeic acid, chlorogenic acid, m-cumaric acid, o-cumaric acid, luteolin-7-O-glucoside, myricetin, resveratrol, rutin and quercetin-3-O-rhamnoside, and 48 volatile compounds belonging to distinct classes. Green peppers produced in the conventional system were the richest in phenolic compounds and had the highest antioxidant activity, as well as those with the highest levels of volatile compounds. On the other hand, peppers produced in organic system showed better visual and tactile quality and lower chemical quality when evaluated by a trained sensory panel. An electronic potentiometric tongue was used, which allowed discriminate peppers according to the system of production and fruits ripeness. In this study, peppers from the conventional production system showed, in general, better quality and better chemical characteristics