Laboratory of Separation and Reaction Engineering

Funder

Organizational Unit

Publications

Monitoring physicochemical and sensory attributes during debittering of stoned green olives

Publication . Marx, Ítala; Rodrigues, Nuno; Veloso, Ana C.A.; Pereira, J.A.; Casal, Susana; Peres, António M.

Stoned green olives are traditional table olives produced in the Northeast of Portugal. They are highly appreciated due to their organoleptic characteristics and levels of complex phenols endowed with strong antioxidant activity, having a significant agro-economic relevance. During the natural debittering process, stoned olives are immersed in water, which is changed (each 1-2 days), leading to a reduction of the initial bitterness and increase of sweetness, turning these green olive edible [1]. Monitoring total phenols contents, the bitterness index as well as the basic sensorial attributes through this washing stage is very important. In this work, the debittering process of 110 samples of stoned green olives (cvs. Cobrançosa and Negrinha de Freixo), was monitoring during 20 days. After each debittering-washing time-period (water changed each 2-days) bitter, pungent and sweet intensities sensations were assessed by trained panelists. Furthermore, the bitterness index and total phenols contents were also evaluated spectrophotometrically. Figure 1 shows the trends observed for the sensory attributes and chemical parameters along the debittering-washing process. From the boxplots (Figure 1), it is clear that bitterness index and total phenols contents significantly decreased with the time, which could be directly related to the observed decrease of the bitter taste intensity (for both olive cultivars) while the decrease of the pungent sensation could be related with the decrease of the total phenols contents, mainly influenced by the increase of the sweet sensation. Furthermore, as can be inferred, the initial bitterness and pungency intensities of cv. Cobrançosa olives were higher than those from cv. Negrinha de Freixo. Nevertheless, after 16-20 days of debittering-washing steps, the bitter and pungent intensities perceived by the trained panelists, for both olive cultivars, were of the same order of magnitude, showing that the debittering procedure adopted was successful and technologically consistent.

2019Conference object

Open access

Fixed-bed and simulated moving bed chromatography using achiral and chiral adsorbents for the complete preparative separation of a quaternary mixture

Publication . Arafah, Rami; Ribeiro, António E.; Rodrigues, Alírio; Pais, Luís S.

Nadolol is a nonselective beta-adrenergic receptor antagonist (beta-blocker) pharmaceutical drug, widely used in the treatment of cardiovascular diseases, such as hypertension, ischemic heart disease (angina pectoris), congestive heart failure and certain arrhythmias. This drug is still being marketed as a mixture of four stereoisomers in spite of the clear evidences that only one of its four stereoisomers has the desired therapeutic effect. Preparative liquid chromatography is actually an accepted route in industry to obtain enantiomeric pure drugs. Today, the combining of different chromatographic technologies, such as fixed-bed and simulated moving bed together with the use of achiral and/or chiral adsorbents are an important improvement in performance of preparative separation of multicomponent chiral drugs into its single pure stereoisomers. This work confirms this improvement using the referred strategy with mobile phase composition optimization at both normal and reversed-phase mode. Different separation strategies were designed and optimized, enlarging the packing materials possibilities, from fully chiral (Chiralpak) to achiral (C18) combined with chiral separation. For each separation step, the optimization of the solvent composition was carried out with pure alcohol, alcohol-hydrocarbon and alcohol-water mixtures, all with a basic modifier (diethylamine), taking into account the strong basic nature of the nadolol.

2022Conference poster

Open access

Effect of malaxation temperature on olive oil chemical and sensory profiles and their evaluation using an electronic tongue

Publication . Marx, Ítala; Rodrigues, Nuno; Veloso, Ana C.A.; Casal, Susana; Pereira, J.A.; Peres, António M.

Olive oil is highly appreciated due to its nutritional and organoleptic characteristics. Olive oils rich in bioactive compounds can be obtained by optimizing the time and temperature of the malaxation process. In this sense, this study aimed investigating the effect of the malaxation temperature (22 to 34°C) on the olive oil's physicochemical and sensory quality and, in more detail, on the phenolic profile. So, virgin olive oils were produced (November 2018), using olives from cv. Cobrancosa. Furthermore, the possibility of using an electronic tongue, i.e., a multisensor potentiometric device, comprising non-specific lipid polymeric with cross-sensitivity sensor membranes, to monitor the malaxation temperature influence on the olive oil's quality and phenolic composition, was evaluated. For that, multivariate statistical tools were developed for discriminating the olive oils according to the malaxation conditions as well as to predict some key quality parameters, including the extinction coefficients (K232, K268 and |ΔK|), free acidity, oxidative stability, peroxide value, bitterness index, total phenols, phenolic composition and gustatory-retronasal positive attributes. The study aims to determine the best malaxation temperature as well as to assess the versatility of the electronic tongue as a single-run, fast and cost-effective analytical device for olive oils quality evaluation.

2019Conference object

Open access

Amino acids profile for assessing Serra da Estrela cheese producers

Publication . Santos, Andreia O.; Falcão, Soraia; Fontes, Luísa; Veloso, Ana C.A.; Lemos, Edite Teixeira de; Lima, M.J. Reis; Peres, António M.; Dias, L.G.

This work has the purpose to evaluate if the Serra da Estrela cheeses colletcted from 6 producers have typical chemical characteristics, with controlled variability, considering that cheeses were produced during time periods, the raw milk comes from different animals, and that the cheese processing may slightly differ between cheesemaking producers.

2019Conference object

Open access

Assessing Serra da Estrela PDO cheeses’ origin-production date using fatty acids profiles

Publication . Lima, M.J. Reis; Bahri, Hamdi; Morais, Jorge Sá; Veloso, Ana C.A.; Fontes, Luísa; Lemos, Edite Teixeira de; Peres, António M.

Serra da Estrela is a Portuguese traditional cheese produced with raw ewe’s milk from “Churra Mondegueira” and “Bordaleira” autochthonous breeds and the wild thistle flower (Cynara cardunculus L.), which benefits from the status of Protected Designation of Origin. Cheese chemical composition, namely the fatty acids profile, depends on milk composition and on manufacturing practices. Thus, the identification of possible chemical biomarkers capable of classifying Serra da Estrela cheeses according to the dairy manufacturing plant, geographical origin or production date would be of utmost relevance for producers and consumers. A typical fatty acids profile, including 23 saturated and unsaturated fatty acids, was identified for the studied cheeses, being butyric, caproic, caprilic, capric, lauric, miristic, palmitic, stearic, oleic, linoleic and its trans-isomer and α-linolenic acids the most abundant ones (relative mean abundances ranging from 1.4% ± 0.5% to 23.9% ± 1.9%). Linear discriminant models were established based on the most discriminative fatty acids (namely, caproic, caprilic, undecanoic, lauric, pentadecanoic, palmitic, palmitoleic, heptadecanoic, oleic, linoleic trans-isomer, heneicosanoic and arachidonic acids) that included less abundant fatty acids, which were selected using the simulated annealing algorithm. The established models enabled assessing cheeses’ origin (models based on 10–12 fatty acids) and/or production date (model based on 20 fatty acids) with predictive sensitivities of 71–88%. Therefore, fatty acids profiles coupled with chemometric techniques, could be foreseen as a fingerprint of cheese’s genuineness, enhancing the consumers’ confidence when purchasing this high-value cheese.

2019Journal article

Open access