Loading...
230 results
Search Results
Now showing 1 - 10 of 230
- Quantifying the Impact of High‐Pressure Processing on the Phenolic Profile, Antioxidant Activity, and Pollen Morphology in HoneyPublication . Scepankova, Hana; Majtan, Juraj; Pospiech, Matej; Moreira, Manuela M.; Pinto, Carlos A.; Dias, Luís G.; Estevinho, Letícia M.; Delerue‐Matos, Cristina; Saraiva, Jorge A.Honey can benefit from non‐thermal processing techniques such as high‐pressure processing (HPP) to improve its quality and bioactivity. This study investigated the impact of HPP (600 MPa for 5, 10, and 15 min) on honey's quality, including the levels of hydroxymethylfurfural (HMF), antioxidant activity, total phenolic content (TPC), and phenolic profile. HPP treatment did not significantly affect HMF or TPC levels but led to selective changes in the phenolic profile. Despite a reduction in certain phenolic compound content, HPP for 5 and 15 min caused a significant increase in the antioxidant activity (2,2‐diphenyl‐1‐picrylhydrazyl [DPPH]) of honey from the mean value of 41.8% to values of 45.4% and 49.6%, respectively. On the other hand, HPP for 10 min did not change the antioxidant activity of tested honey. A 27.5% reduction in the equatorial diameter of pollen grains was observed after HPP combined with temperature at 75°C, suggesting an improved release of bioactive compounds. The content of specific phenolic compounds, including caffeic acid, p‐coumaric acid, sinapic acid, naringin, kaempferol, and the TPC, significantly affected the DPPH activity. The increment in the antioxidant activity of HPP honey may be attributed to selective changes in the content of certain phenolic compounds and improved their extraction from pollen grains.
- Melipona scutellaris geopropolis: chemical composition and bioactivityPublication . Coutinho, Sónia; Matos, Vanessa; Seixas, Natália; Rodrigues, Hellen; Paula, Vanessa B.; Freitas, Lais; Dias, Teresa; Santos, Francisco de A.R.; Dias, L.G.; Estevinho, Leticia M.Geopropolis has been used in traditional medicine for centuries. In this study, the botanical origin, physicochemical profile, and biological activities of geopropolis from Melipona scutellaris harvested during rainy and dry seasons were investigated. Palynological analysis identified over 50 pollen types, with Schinus terebinthifolius and Cecropia being the predominant types. The analytical results were in line with those reported in the literature. Rainy-season geopropolis exhibited higher total phenol and flavonoid content (determined using High Performance Liquid Chromatography-25.13% and 3.92%, respectively) compared to the dry season (19.30% and 2.09%); the major peaks (naringin, gallic acid, and catechin) were similar among samples. Antioxidant capacity was assessed via DPPH, reducing power, and beta-carotene/linoleic acid discoloration assays. Rainy-season samples displayed superior antioxidant activity across methods. Antimicrobial effects were determined using microdilution, while the impact on the cholinesterase enzyme was quantified using 5-thio-2-nitrobenzoic acid accumulation. Anti-inflammatory and antimutagenic activities were assessed through hyaluronidase enzyme inhibition and by utilizing Saccharomyces cerevisiae ATCC-20113 cells. Both samples exhibited anti-inflammatory and antimutagenic properties. Moreover, a significant inhibition of acetylcholinesterase was observed, with IC50 values of 0.35 mu g/mL during the rainy season and 0.28 mu g/mL during the dry season. Additionally, the geopropolis displayed antimicrobial activity, particularly against Staphylococcus aureus. These findings suggest the therapeutic potential of M. scutellaris geopropolis in the context of inflammatory, oxidative, and infectious diseases.
- The Effect of Incorporating Fermented Elderberries (Sambucus nigra) into Bread: Quality, Shelf Life, and Biological EnhancementPublication . Seixas, Natália; Paula, Vanessa B.; Dias, Teresa; Dias, Luís G.; Estevinho, Letícia M.Elderberries, known for their antioxidant, anti-inflammatory, and antiviral properties, have traditionally been used to prevent and treat infections and boost the immune system. By increasing the quantity and quality of certain compounds, fermentation can potentially make them more effective as food additives. The aim of this study was to evaluate the effect of incorporating fermented elderberries on the bioactivity and shelf life of a traditional bread. The elderberry fermentation process was optimised using Saccharomyces cerevisiae, guided by a Plackett–Burman experimental design. The aim was to assess the impact of incorporating fermented elderberries into bread on its bioactive properties and shelf life. The fermentation of the elderberries was found to enhance their bioactive compounds and antioxidant activity. The total phenolic content ranged from 8.63 to 20.56 mg GAE/g (in samples without and with 2% extract, respectively). The antioxidant capacity, measured using the FRAP method, also showed a significant increase with the addition of the extract (from 9.16 to 26.66 mg Fe (II) E/g of the sample). Furthermore, bread enriched with fermented elderberry extracts demonstrated an extended shelf life during the study period.
- Can near-infrared spectroscopy replace a panel of tasters in sensory analysis of dry-cured bísaro loin?Publication . Vasconcelos, Lia; Dias, L.G.; Leite, Ana; Ferreira, Iasmin da Silva; Pereira, Etelvina; Bona, Evandro; Mateo, Javier; Rodrigues, Sandra; Teixeira, AlfredoThis study involved a comprehensive examination of sensory attributes in dry-cured Bísaro loins, including odor, androsterone, scatol, lean color, fat color, hardness, juiciness, chewiness, flavor intensity and flavor persistence. An analysis of 40 samples revealed a wide variation in these attributes, ensuring a robust margin for multivariate calibration purposes. The respective near-infrared (NIR) spectra unveiled distinct peaks associated with significant components, such as proteins, lipids and water. Support vector regression (SVR) models were methodically calibrated for all sensory attributes, with optimal results using multiplicative scattering correction pre-treatment, MinMax normalization and the radial base kernel (non-linear SVR model). This process involved partitioning the data into calibration (67%) and prediction (33%) subsets using the SPXY algorithm. The model parameters were optimized via a hybrid algorithm based on particle swarm optimization (PSO) to effectively minimize the root-mean-square error (RMSECV) derived from five-fold cross-validation and ensure the attainment of optimal model performance and predictive accuracy. The predictive models exhibited acceptable results, characterized by R-squared values close to 1 (0.9616–0.9955) and low RMSE values (0.0400–0.1031). The prediction set’s relative standard deviation (RSD) remained under 5%. Comparisons with prior research revealed significant improvements in prediction accuracy, particularly when considering attributes like pig meat aroma, hardness, fat color and flavor intensity. This research underscores the potential of advanced analytical techniques to improve the precision of sensory evaluations in food quality assessment. Such advancements have the potential to benefit both the research community and the meat industry by closely aligning their practices with consumer preferences and expectations.
- Contribution to Characterizing the Meat Quality of Protected Designation of Origin Serrana and Preta de Montesinho Kids Using the Near-Infrared Reflectance MethodologyPublication . Vasconcelos, Lia; Dias, L.G.; Leite, Ana; Pereira, Etelvina; Silva, Severiano; Ferreira, Iasmin; Mateo, Javier; Rodrigues, Sandra; Teixeira, AlfredoThe aims of this study were to describe and compare the meat quality characteristics of male and female kids from the "Serrana" and "Preta de Montesinho" breeds certified as "Cabrito Transmontano" and reinforce the performance of near-infrared reflectance (NIR) spectra in predicting these quality characteristics and discriminating among breeds. Samples of Longissimus thoracis (n = 32; sixteen per breed; eight males and eight females) were used. Breed significantly affected meat quality characteristics, with only color and fatty acid (FA) (C12:0) being influenced by sex. The meat of the "Serrana" breed proved to be more tender than that of the "Preta de Montesinho". However, the meat from the "Preta de Montesinho" breed showed higher intramuscular fat content and was lighter than that from the "Serrana" breed, which favors its quality of color and juiciness. The use of NIR with the linear support vector machine regression (SVMR) classification model demonstrated its capability to quantify meat quality characteristics such as pH, CIELab color, protein, moisture, ash, fat, texture, water-holding capacity, and lipid profile. Discriminant analysis was performed by dividing the sample spectra into calibration sets (75 percent) and prediction sets (25 percent) and applying the Kennard-Stone algorithm to the spectra. This resulted in 100% correct classifications with the training data and 96.7% accuracy with the test data. The test data showed acceptable estimation models with R2 > 0.99.
- SVM regression to assess meat characteristics of bisaro pig loins using nirs methodologyPublication . Vasconcelos, Lia; Dias, L.G.; Leite, Ana; Ferreira, Iasmin da Silva; Pereira, Etelvina; Silva, Severiano; Rodrigues, Sandra; Teixeira, AlfredoThis study evaluates the ability of the near infrared reflectance spectroscopy (NIRS) to estimate the aW, protein, moisture, ash, fat, collagen, texture, pigments, and WHC in the Longissimus thoracis et lumborum (LTL) of Bisaro pig. Samples (n = 40) of the LTL muscle were minced and scanned in an FT-NIR MasterTM N500 (BuCHI) over a NIR spectral range of 4000-10,000 cm(-1) with a resolution of 4 cm(-1). The PLS and SVM regression models were developed using the spectra's math treatment, DV1, DV2, MSC, SNV, and SMT (n = 40). PLS models showed acceptable fits (estimation models with RMSE <= 0.5% and R-2 >= 0.95) except for the RT variable (RMSE of 0.891% and R-2 of 0.748). The SVM models presented better overall prediction results than those obtained by PLS, where only the variables pigments and WHC presented estimation models (respectively: RMSE of 0.069 and 0.472%; R-2 of 0.993 and 0.996; slope of 0.985 +/- 0.006 and 0.925 +/- 0.006). The results showed NIRs capacity to predict the meat quality traits of Bisaro pig breed in order to guarantee its characterization.
- Phenolic Class Analysis in Honey: Comparison of Classical and Single UV Spectrum MethodologiesPublication . Paula, Vanessa B.; Sousa-Dias, Miguel L.; Seixas, Natália; Combarros-Fuertes, Patricia; Estevinho, Leticia M.; Dias, L.G.The analytical results from a study of 16 honey samples (extra white to dark honey color range) of phenolic compounds obtained using the single UV spectrum methodology and classical spectrophotometric methods (Folin–Ciocalteu and AlCl3 methods) are presented. The first method quantified all classes of phenolic compounds in honey’s SPE-C18 extract: the total hydroxybenzoic acid content (concentrations between 0.37 ± 0.05 and 4.46 ± 0.37 mg of gallic acid/g of honey), total hydroxycinnamic acid content (0.13 ± 0.03 and 2.76 ± 0.13 mg of ferulic acid/g of honey), and total flavonoid content (0.15 ± 0.03 and 1.63 ± 0.17 mg of quercetin/g of honey). The total phenolic contents were, on average, 1.86 ± 0.72 and 1.78 ± 0.79 times higher than the results obtained for raw honey and the SPE-C18 extract, respectively, using the classical Folin–Ciocalteu method. The total flavonoid contents, on average, were 6.02 ± 3.14 times larger and 0.66 ± 0.33 times smaller than the results obtained using the classical AlCl3 method for raw honey and SPE-C18 extract, respectively.
- 10º Encontro Nacional de Cromatografia: livro de resumosPublication . Peres, António M. (Ed.); Barros, Lillian (Ed.); Dias, L.G. (Ed.); Ferreira, Isabel C.F.R. (Ed.)Este livro contém os resumos de todas as comunicações apresentadas no 10º Encontro Nacional de Cromatografia, realizado no Instituto Politécnico de Bragança, de 4 a 6 de Dezembro de 2017
- Comparative study of different Portuguese samples of propolis: pollinic, sensorial, physicochemical, microbiological characterization and antibacterial activityPublication . Dias, L.G.; Pereira, Ana Paula; Estevinho, Leticia M.The aim of this work was to study four propolis samples from Trás-os-Montes region of Portugal. The propolis samples’ color was different, which pollen analysis showed to be due to different botanical sources: Populus sp., Pinus sp., Quercus sp. and Castanea sativa. The data from physicochemical analysis (moisture, soluble and insoluble solids content, pH, conductivity, ash content, wax, total phenolics and flavonoids content) was treated using multivariate statistical tools as cluster heat map, principal components analysis and linear discriminant analysis with the purpose of classifying the sample accordingly to the botanical/geographical origin. The discriminant analysis was applied with stepwise to select the variables that most contribute to sample identification accordingly to pollinic profile. The cross-validation technique was applied, using the leave-one-out procedure, which showed good prediction capabilities of the samples. Microbiologically, the commercial quality was satisfactory, since the samples didn’t contain deterioration or pathogenic microorganisms. All the samples studied presented antimicrobial activity against Methicillin-resistant Staphylococcus aureus, in a dose dependent way. The antimicrobial activity was strictly related to the physicochemical composition. This work will allow connecting a particular chemical propolis type to a specific type of biological activity, what is essential for the use in therapeutic applications.
- Evaluation of an electronic tongue for honey classification according to its pollen analysisPublication . Sousa, Mara E.B.C.; Dias, L.G.; Peres, António M.; Estevinho, Leticia M.; Machado, Adélio A.S.C.Electronic tongues (ET) have attracted great interest due to its potential to obtain global Information from complex samples that could hardly be obtained by traditional instrumental methods of analysis. These multi-sensor arrays provide a huge amount of sample information which, by applying chemometric methods, allows sample identification/ classification, taste evaluation as well as, multicomponent analysis. The method of operation consists In obtaining a signal pattern which corresponds to the overall Information on the sample using chemical sensors with high stability and cross sensitivity to different species in solution. In this work, a potenclometrlc electronic tongue or taste sensor array was used. The device had 20 sensors, based on all-solid-state electrodes with lipid polymeric membranes formed on solid conducting silver supports.