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Projeto de investigação
Mediterranean Institute for Agriculture, Environment and Development
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Dcmc as a promising alternative to bentonite in white wine stabilization. Impact on protein stability and wine aromatic fraction
Publication . Saracino, Francesco; Brinco, João; Gago, Diana; Gomes da Silva, Marco; Boavida Ferreira, Ricardo; Ricardo-Da-silva, Jorge; Chagas, Ricardo; Ferreira, Luísa Maria; CENSE - Centro de Investigação em Ambiente e Sustentabilidade; DQ - Departamento de Química; LAQV@REQUIMTE; MDPI - Multidisciplinary Digital Publishing Institute
Protein haze in white wine is one of the most common non-microbial defects of commercial wines, with bentonite being the main solution utilized by the winemaking industry to tackle this problem. Bentonite presents some serious disadvantages, and several alternatives have been pro-posed. Here, an alternative based on a new cellulose derivative (dicarboxymethyl cellulose, DCMC) is proposed. To determine the efficiency of DCMC as a bentonite alternative, three monovarietal wines were characterized, and their protein instability and content determined by a heat stability test (HST) and the Bradford method, respectively. The wines were treated with DCMC to achieve stable wines, as shown by the HST, and the efficacy of the treatments was assessed by determining, before and after treatment, the wine content in protein, phenolic compounds, sodium, calcium, and volatile organic compounds (VOCs) as well as the wine pH. DCMC applied at dosages such as those commonly employed for bentonite was able to reduce the protein content in all tested wines and to stabilize all but the Moscatel de Setúbal varietal wine. In general, DCMC was shown to induce lower changes in the wine pH and phenolic content than bentonite, reducing the wine calcium content. Regarding which VOCs are concerned, DCMC produced a general impact similar to that of bentonite, with differences depending on wine variety. The results obtained suggest that DCMC can be a sustainable alternative to bentonite in protein white wine stabilization.
Unveiling Chemical Cues of Insect-Tree and Insect-Insect Interactions for the Eucalyptus Weevil and Its Egg Parasitoid by Multidimensional Gas Chromatographic Methods
Publication . Mendes, Davide; Branco, Sofia; Paiva, Maria Rosa; Schütz, Stefan; Mateus, Eduardo P.; Silva, Marco Gomes da; LAQV@REQUIMTE; DQ - Departamento de Química; CENSE - Centro de Investigação em Ambiente e Sustentabilidade; DCEA - Departamento de Ciências e Engenharia do Ambiente; MDPI - Multidisciplinary Digital Publishing Institute
Multidimensional gas chromatography is, presently, an established and powerful analytical tool, due to higher resolving power than the classical 1D chromatographic approaches. Applied to multiple areas, it allows to isolate, detect and identify a larger number of compounds present in complex matrices, even in trace amounts. Research was conducted to determine which compounds, emitted by host plants of the eucalyptus weevil, Gonipterus platensis, might mediate host selection behavior. The identification of a pheromone blend of G. platensis is presented, revealing to be more attractive to weevils of both sexes, than the individual compounds. The volatile organic compounds (VOCs) were collected by headspace solid phase microextraction (HS-SPME), MonoTrap™ disks, and simultaneous distillation-extraction (SDE). Combining one dimensional (1D) and two-dimensional (2D) chromatographic systems—comprehensive and heart-cut two-dimensional gas chromatography (GC×GC and H/C-MD-GC, respectively) with mass spectrometry (MS) and electroantennographic (EAD) detection, enabled the selection and identification of pertinent semiochemicals which were detected by the insect antennal olfactory system. The behavioral effect of a selected blend of compounds was assessed in a two-arm olfactometer with ten parallel walking chambers, coupled to video tracking and data analysis software. An active blend, composed by cis and trans-verbenol, verbenene, myrtenol and trans-pinocarveol was achieved.
Novel Machine Learning-Based Approach for Determining Milk Clotting Time Using Sheep Milk
Publication . Dias, João; Gomes, Sandra; Silvério, Karina S.; Freitas, Daniela; Fernandes, Jaime; Martins, João; Jasnau Caeiro, José; Lageiro, Manuela; Alvarenga, Nuno; GeoBioTec - Geobiociências, Geoengenharias e Geotecnologias; Faculdade de Ciências e Tecnologia (FCT); DCT - Departamento de Ciências da Terra; MDPI - Multidisciplinary Digital Publishing Institute
The enzymatic coagulation of milk, crucial in cheese production, entails the hydrolysis of κ-casein and subsequent micelle aggregation. Conventional assessment standards, such as the Berridge method, depend on visual inspection and are susceptible to operator bias. Recent methods for the identification of milk-clotting time rely on optical, ultrasonic, and image-based technologies. In the present work, the composition of milk was evaluated through standard methods from ISO and AOAC. Milk coagulation time (MCT) was measured through viscosimetry, Berridge’s operator-driven technique, and a machine learning approach employing computer vision. Coagulation was additionally observed using the Optigraph, which measures micellar aggregation through near-infrared light attenuation for immediate analysis. Sheep milk samples were analysed for their composition and coagulation characteristics. Coagulation times, assessed via Berridge (BOB), demonstrated high correlation (R2 = 0.9888) with viscosimetry (Visc) and machine learning (ML). Increased levels of protein and casein were linked to extended MCT, whereas lower pH levels sped up coagulation. The calcium content did not have a notable impact. Optigraph assessments validated variations in firmness and aggregation rate. Principal Component Analysis (PCA) identified significant correlations between total solids, casein, and MCT techniques. Estimates from ML-based MCT closely align with those from operator-based methods, confirming its dependability. This research emphasises ML as a powerful, automated method for evaluating milk coagulation, presenting a compelling substitute for conventional approaches.
Impact of temperature during beer storage on beer chemical profile
Publication . Ferreira, Inês M.; Freitas, Flávia; Pinheiro, Sara; Mourão, Maria Filipa; Guido, Luís Ferreira; Gomes da Silva, Marco; LAQV@REQUIMTE; DQ - Departamento de Química; Elsevier Science B.V., Amsterdam.
Aiming to gain insights into the impact of storage conditions on the chemical profile of beer samples, changes on the relative amount of several chemical classes of compounds was monitored. The influence of storage conditions was statistically discerned using the hierarchical cluster analysis complemented by heatmap date visualization. Aldehydes, furanic compounds and esters showed a clear role in beers stored at 37 ± 1 °C (contribution >1, as obtained in the heatmap data visualization). The reaction rate constant and temperature dependence was well described by the Arrhenius equation for these compound classes, for which the reaction rate increased with increasing temperatures. The rate of development of furanic compounds, aldehydes and esters showed to be almost 140, 90 and 20 times higher in beers stored at higher temperatures (37 ± 1 °C) when compared to beers stored at 4 ± 1 °C, respectively. These results indicate that temperature was the main parameter contributing to the major changes in beer chemical profile. Through olfactometric analysis, the major difference was found in aged beers, both naturally and forced aged, where the prevalence of sweet and papery aroma notes were noticed, linked to the development of β-damascenone and E-2-nonenal, respectively.
Modified Atmosphere Packaging (MAP) for Seaweed Conservation
Publication . Moreira-Leite, Bruno; Antunes, Rafael; Cotas, João; Martins, Nuno; Costa, Nuno; Noronha, João P.; Mata, Paulina; Diniz, Mário; DQ - Departamento de Química; LAQV@REQUIMTE; UCIBIO - Applied Molecular Biosciences Unit; MDPI - Multidisciplinary Digital Publishing Institute
Conventional conservation techniques such as drying, salting or freezing do not allow for preserving the original characteristics of seaweeds. The present work aims to study the impact of minimal processing, in particular “Modified Atmosphere Packaging” (MAP), on the physicochemical characteristics and food safety of two seaweed species, “laver” (Porphyra umbilicalis) and “sea-lettuce” (Ulva lactuca), stored at 6 °C for 15 days. Different parameters were evaluated using analytical methods, namely the composition of headspace gases, color, texture, microorganisms, and volatile organic compounds (VOCs). The main findings of this study were that the MAP treatment was able to inhibit the respiration rate of minimally processed seaweeds, also preserving their color and texture. There was a remarkable reduction in the microbial load for P. umbilicalis treated under modified and vacuum atmospheres, and U. lactuca exhibited relatively steady values with no notable differences between the treatments and the control. Therefore, during the 15-day study period, both seaweeds met the requirements for food safety. GC–TOF-MS allowed to conclude that both MAP and vacuum treatments were more efficient in maintaining the odor characteristics of U. lactuca compared to P. umbilicalis with no significant differences throughout the storage days. Metabolic responses to diverse sources of abiotic stress seemed to account for most of the changes observed.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/05183/2020