Browsing by Author "Zaghdoudi, Khalil"
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- Aesculus hippocastanum L.: a simple ornamental plant or a source of compelling molecules for industry?Publication . Dridi, Asma; Reis, Filipa S.; Pires, Tânia C.S.P.; Calhelha, Ricardo C.; Pereira, Carla; Zaghdoudi, Khalil; Ferreira, Isabel C.F.R.; Barros, Lillian; Barreira, João C.M.Aesculus hippocastanum L., also known as horse chestnut, is an ornamental tree whose seeds are mostly discarded in landfills in the regions where they are grown. However, recent studies have shown that these seeds can be a source of interesting compounds for several industries. This work aimed to chemically characterize horse chestnut seeds at the level of compounds recognized for their wide bioactivity, i.e., organic acids, including phenolic compounds, using chromatographic methodologies (UFLC-DAD and LC-DAD-ESI/MSn). In addition, the bioactivity of these seeds was evaluated by in vitro methodologies, seeking to relate the respective (bio)activity to the compounds present in the endocarp (husk), seed coat (skin), and peeled seed (pulp). The antioxidant activity (lipid peroxidation inhibition and oxidative haemolysis inhibition), antibacterial potential (against Gram-positive and Gram-negative bacteria) and cytotoxicity (in human tumour cell lines and porcine liver primary cells) were evaluated. Kaempferol-O-pentoside-O-hexoside-O-hexoside was the main phenolic identified in the pulp. At the same time, (-)-epicatechin and beta-type (epi)catechin dimer were the major phenolics present in husk and skin, respectively. In general, A. hippocastanum extracts presented antioxidant and antibacterial potential, without toxicity up to the maximal tested dose. Overall, these findings anticipate potential applications of A. hippocastanum seeds in food- or pharmaceutical-related uses.
- A kinetic-thermodynamic study of the effect of the cultivar/total phenols on the oxidative stability of olive oilsPublication . Veloso, Ana C.A.; Rodrigues, Nuno; Ouarouer, Yosra; Zaghdoudi, Khalil; Pereira, J.A.; Peres, António M.Physicochemical parameters, total phenols contents (TPC), and oxidative stabilities at 120–160 C were evaluated for two monovarietal (Arbequina and Cobrançosa cultivars, cvs.) and one blend extra-virgin olive oil, confirming the label quality grade and allowing grouping them according to the different TPC (TPC = 88 7, 112 6 and 144 4 mg CAE/kg, for cv. Arbequina, blend and cv. Cobrançosa oils, respectively). The lipid oxidation rate increased with the decrease of the TPC, being Cobrançosa oils (higher TPC) more thermally stable. Kinetic-thermodynamic parameters were determined using the activated complex/transition- state theory and the values did not significantly differ for Cobrançosa and blend oils, which had the highest TPC, suggesting a hypothetically threshold saturation of the beneficial effect. Cobrançosa oils had a significant more negative temperature coefficient, higher temperature acceleration factor, greater activation energy and frequency factor, higher positive enthalpy of activation, lower negative entropy of activation, and greater positive Gibbs free energy of activation, probably due to the higher TPC. The results confirmed that lipid oxidation was a nonspontaneous, endothermic, and endergonic process with activated formed complexes structurally more ordered than the reactants. A negative deviation from the Arrhenius behavior was observed for all oils being the super-Arrhenius behavior more marked for Arbequina oils that had the lowest TPC. Finally, the kineticthermodynamic parameters allowed classifying oils according to the binomial olive cultivar/total phenols level, being the temperature acceleration factor and the Gibbs free energy of activation at 160º C the most powerful discriminating parameters.
- Kinetic-thermodynamic study of the oxidative stability of Arbequina olive oils flavored with lemon verbena essential oilPublication . Cherif, Marwa; Rodrigues, Nuno; Veloso, Ana C.A.; Zaghdoudi, Khalil; Pereira, J.A.; Peres, António M.Arbequina extra-virgin olive oils were flavored with lemon verbena (Aloysia citrodora) essential oil (0.1–0.4%, w/w), being evaluated quality parameters (free acidity, peroxide value, UV-extinction coefficients), oxidative stability, antioxidant and total reducing capacity. The kinetic-thermodynamic nature of the lipid oxidation was evaluated by Rancimat (110–150 °C). The essential oil addition promoted the antioxidant and total reducing capacities but, unfortunately, increased primary and secondary related quality parameters. Moreover, flavoring decreased the oils' oxidative stability. The kinetic-thermodynamic data showed that unflavored oils had significantly lower oxidation reaction rates (0.055–0.06492 h−1), more negative temperature coefficient (−0.0268°C−1), higher temperature acceleration factor (1.852), greater activation energy (82.7 kJ mol−1) and frequency factor (10.9 × 109 h−1), higher positive enthalpy of activation (79.4 kJmol-1), lower negative entropy of activation (−131.8 J mol−1K−1) and greater positive Gibbs free energy of activation (129.95–135.23 kJ mol−1), showing that oils’ oxidation was negatively influenced by the essential oil incorporation. Overall, oxidation had a non-spontaneous, endothermic and endergonic nature. Finally, olive oils could be satisfactorily classified (principal component and linear discriminant analysis) according to the flavoring level, using quality-antioxidant-stability or kinetic-thermodynamic datasets. The latter showed a less predictive performance, although ensuring the full discrimination of unflavored from flavored oils.
- A lab-made e-nose-MOS device for assessing the bacterial growth in a solid culture mediumPublication . Dias, Teresa; Santos, Vitor S.; Zorgani, Tarek; Ferreiro, Nuno Manuel; Rodrigues, Ana Isabel; Zaghdoudi, Khalil; Veloso, Ana C.A.; Peres, António M.The detection and level assessment of microorganisms is a practical quality/contamination indicator of food and water samples. Conventional analytical procedures (e.g., culture methods, immunological techniques, and polymerase chain reactions), while accurate and widely used, are time-consuming, costly, and generate a large amount of waste. Electronic noses (E-noses), combined with chemometrics, provide a direct, green, and non-invasive assessment of the volatile fraction without the need for sample pre-treatments. The unique olfactory fingerprint generated during each microorganism’s growth can be a vehicle for its detection using gas sensors. A lab-made E-nose, comprising metal oxide semiconductor sensors was applied, to analyze solid medium containing Gram-positive (Enterococcus faecalis and Staphylococcus aureus) or Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. The electrical-resistance signals generated by the E-nose coupled with linear discriminant analysis allowed the discrimination of the four bacteria (90% of correct classifications for leave-one-out cross-validation). Furthermore, multiple linear regression models were also established allowing quantifying the number of colony-forming units (CFU) (0.9428 ≤ R2 ≤ 0.9946), with maximum root mean square errors lower than 4 CFU. Overall, the E-nose showed to be a powerful qualitative–quantitative device for bacteria preliminary analysis, being envisaged its possible application in solid food matrices.
- Recovery of anthocyanins from passion fruit epicarp for food colorants: Extraction process optimization and evaluation of bioactive propertiesPublication . Ghada, Bejaoui; Pereira, Eliana; Pinela, José; Prieto Lage, Miguel A.; Pereira, Carla; Calhelha, Ricardo C.; Stojković, Dejan; Soković, Marina; Zaghdoudi, Khalil; Barros, Lillian; Ferreira, Isabel C.F.R.The potential of passion fruit (Passiflora edulis Sims) epicarp to produce anthocyanin-based colorants with bioactive properties was evaluated. First, a five-level three-factor factorial design coupled with response surface methodology was implemented to optimize the extraction of anthocyanins from dark purple epicarps. The extraction yield and cyanidin-3-O-glucoside content were used as response criteria. The constructed models were fitted to the experimental data and used to calculate the optimal processing conditions (t = 38 min, T = 20 °C, S = 0% ethanol/water (v/v) acidified with citric acid to pH 3, and RS/L = 50 g/L) that lead to maximum responses (3.4 mg/g dried epicarp and 9 mg/g extract). Then, the antioxidant, antimicrobial, and cytotoxic activities of anthocyanin extracts obtained using the optimized method and a conventional extraction method were evaluated in vitro. The extract obtained by the optimized method revealed a higher bioactivity, in agreement with the higher cyanidin-3-O-glucoside content. This study highlighted the coloring and bioactive potential of a bio-based ingredient recycled from a bio-waste, which promotes a sustainable bioeconomy in the agri-food sector.
- Tools to develop dairy ingredients: bioactive and preservative purposesPublication . Khouja, Dora; Fernandes, Filipa Alexandra; Carocho, Márcio; Calhelha, Ricardo C.; Rodrigues, Paula; Zaghdoudi, Khalil; Barros, Lillian; Heleno, Sandrina A.; Ferreira, Isabel C.F.R.Phytosterols can be ingested and consequently absorbed by the human body, leading to a direct absorption competition with cholesterol, thus reducing its absorption [1]. Mushrooms are described as having several bioactive components, such as mycosterols (ergosterol), which, similarly to phytosterols, exhibit a strong hypocholesterolemic potential [2]. Thus, the objective of this work was to obtain mycosterol enriched extracts from A. bisporus L. bio-waste for further incorporation in sheep cottage cheese, in order to develop a functional food with hypocholesterolemic effects. Sheep cottage cheeses with pure ergosterol, and a control cheese with no incorporation were prepared. The extracts were obtained by ultrasound assisted extraction (UAE) and the identification and quantification of their compounds was achieved through HPLC-UV. The toxicity and hypocholesterolemic activity were sought through a CaCo2 cell line. In terms of analysis, the nutritional value was analyzed according to AOAC procedures, the physical parameters included texture, external colour and water activity, and the microbial load (total aerobic mesophiles, enterobacteria, Psychrotrophic bacteria, yeasts, molds and Staphylococcus aureus) was also analyzed along a shelf life of 9 days according to the International Organization for Standardization (ISO) 6887-1:2003 [3,4]. No significant differences were verified for the nutritional parameters. The color of the cheeses incorporated with the extract hinted towards a browner tone when compared to the other two samples (cottage cheese with ergosterol and control cottage cheese). A dominance of palmitic acid followed by oleic and capric acids was detected, being the saturated fatty acids the predominant ones. Lactose and glucose were the two detected soluble sugars; being glucose only observed in cheese incorporated with A. bisporus, probably present in the extract. Also, the incorporations did not cause any significant alterations to normal microbial growth. Despite an increase of enterobacteria in the cheeses with the incorporation of the two agents, this increase was also verified for the control cottage cheese. CaCo2 cells absorbed 43.89% of cholesterol from the control cheese, while the cheese with pure ergosterol reduced cholesterol absorption by approximately 21.1%, and cheese with A. bisporus by approximately 30.24%. These results highlight the capacity of ergosterol to reduce the absorption of cholesterol, being an interesting candidate for the development of functional foods.