Kinetic-thermodynamic study of the oxidative stability of Arbequina olive oils flavored with lemon verbena essential oil

Arbequina extra-virgin olive oils were flavored with lemon verbena (Aloysia citrodora) essential oil (0.10.4%, 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 (110150 °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 (0.0550.06492 h1), more negative temperature coefficient (0.0268°C1), higher temperature acceleration factor (1.852), greater activation energy (82.7 kJ mol1) and frequency factor (10.9 × 109 h1), higher positive enthalpy of activation (79.4 kJmol-1), lower negative entropy of activation (131.8 J mol1K1) and greater positive Gibbs free energy of activation (129.95135.23 kJ mol1), 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.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) and to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. Nuno Rodrigues thanks the National funding by FCT- Foundation for Science and Technology, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

A kinetic-thermodynamic study of the effect of the cultivar/total phenols on the oxidative stability of olive oils

Physicochemical parameters, total phenols contents (TPC), and oxidative stabilities at 120160 °C were evaluated for two monovarietal (Arbequina and Cobrançosa cultivars, cvs.) and one blend extravirgin olive oil, confirming the label quality grade and allowing grouping them according to the different TPC (TPC = 88±7, 112±6 and 144±4mg 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. Kineticthermodynamic parameters were determined using the activated complex/transitionstate 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 superArrhenius 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 160 °C the most powerful discriminating parameters.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support to CIMO (UIDB/00690/2020) and to CEB (UIDB/04469/2020) units and to BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte). 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

Recovery of anthocyanins from passion fruit epicarp for food colorants: Extraction process optimization and evaluation of bioactive properties

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.This research was funded by the European Regional Development Fund (FEDER) through the Regional Operational Program North 2020, within the scope of Project NORTE-01-0145-FEDER-023289: DeCodE, and project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural®, and also by the Interreg España-Portugal through the project 0377_Iberphenol_6_E. National funding by the Portuguese Foundation for Science and Technology (FCT, P.I., through the institutional scientific employment program-contract for J. Pinela, R.C. Calhelha and L. Barros. Funding by the Ministry of Education, Science and Technological Development, Republic of Serbia, grant No. 173032. Financial support (P.P. 0000 421S 140.08) from GAIN (Xunta de Galicia) to M.A. Prieto through a post-doctoral (modality B) grant. To the Portuguese Foundation for Science and Technology (FCT) and European Regional Development Fund (ERDF – FEDER) under Program PT2020 for financial support to CIMO (UIDB/00690/2020).info:eu-repo/semantics/publishedVersio

Optimisation de l’extraction des caroténoïdes à partir du persimmon (Diospyros kaki L.), de l’abricot (Prunus armeniaca L.) et de la pêche (Prunus persica L.) : étude photophysique en vue d’une application en thérapie photodynamique (PDT)

Photodynamic therapy (PDT) is a clinically used technique for treating skin diseases, age-relatedmacular degeneration but mainly some types of cancer. PDT involves three components: a photosensitive molecule named photosensitizer (PS), light and oxygen. After administration of the PS, this one will be located more or less selectively in tumoral regions where it is activated by light irradiation at appropriate wavelength and power. This leads to the formation of highly reactive and cytotoxic reactive oxygen species (ROS), especially singlet oxygen, resulting in the destruction of the tumor by necrosis or apoptosis. To improve the treatment selectivity, different strategies are being exploited, one of which is the development of "photodynamic molecular beacons" (PMB). In PMB the photosensitizer is linked via a peptide to an inhibitor of 1O2 (quencher). This quencher inhibits the formation of 1O2 as long as the compound has not reached its target, namely cancer cells. In order to inhibit the toxicity of the PS in non-target cells and restore toxicity only close to the biological target, it is necessary to find an adequate PS/quencher couple. This remains a challenge for PDT. Carotenoids are interesting candidates due to their specific photophysical properties and ability to inhibit 1O2, which makes them potential quenchers for building PMBs. In plants, carotenoids (carotenes and xanthophylls) are pigments involved in the photosynthesis, in which they play two main roles: a light collecting role and a protecting role by preserving the photosynthetic systems against photoxydative damages induced by a too intense light exposure. This protection can for instance occur via the well-known xanthophylls cycle. This capacity to catch energy presents a potential interest that should not be neglected in the framework of the design of PMBs usable in photodynamic therapy. Within the framework as part of this PhD thesis in Cotutelle with the Faculty of Sciences of Bizerte, we focused on carotenoids from three fruits produced in Tunisia: persimmon (Diospyros kaki L.), apricot (Prunus armeniaca L.) and peache (Prunus persica L.), known for their global richness in these natural pigments. Three extraction processes were investigated: (i) the Soxhlet extraction based on the use of organic solvent at atmospheric pressure and used as reference, (ii) the accelerated solvent extraction (ASE) using organic solvent under high pressure, and (iii) the supercritical fluid extraction (SFE) using supercritical CO2 and ethanol as cosolvent. For these two last processes, a design of experiments (Surface Response Design) was used to identify the key factors and optimal extraction conditions of various carotenoids (pressure, temperature, flow, % cosolvent, time, number of cycles). Then, HPLC-PDA coupled with mass spectrometry (MS) enabled the identification and quantification of carotenoids from the extracts. Thus it was possible to compare the profiles in carotenoids content from each fruit as well as the performances of each extraction process. This study showed that the carotenoidic profile in the persimmon was the most interesting as compared to the profiles in the two other fruits. Extraction and purification of the carotenoids from persimmon by preparative high pressure liquid chromatography were then performed in order to have a sufficient amount of each carotenoid and sometimes of their conformational isomers. We finally performed a study of their photophysical properties (absorption, fluorescence emission, 1O2 inhibition) in order to evaluate their potential as 1O2 quencher in molecular construction such as a PMBLa thérapie photodynamique (PDT) est une technique utilisée cliniquement pour traiter certaines maladies de la peau, la dégénérescence maculaire liée à l’âge et certains types de cancer. Elle fait intervenir trois composants : une molécule photosensible ou photosensibilisateur (PS), la lumière et l’oxygène. Après administration du PS, celui-ci va se localiser plus ou moins sélectivement dans les zones tumorales où il est alors activé par irradiation lumineuse à une longueur d’onde et une puissance données. Ceci engendre la formation d’espèces réactives de l’oxygène (ROS) très réactives, dont l'oxygène singulet1 O2, qui entraînent la destruction des tissus tumoraux par nécrose ou apoptose. Afin d’améliorer la sélectivité du traitement, différentes pistes sont actuellement exploitées dont l’élaboration de « photodynamic molecular beacons » (PMB). Dans un PMB, le photosensibilisateur (PS) est associé via un peptide à un inhibiteur 1O2, appelé quencher. Ce quencher inhibe la formation d’1O2 tant que le composé n’a pas atteint sa cible. Une fois la zone cancéreuse atteinte, des enzymes spécifiques clivent le peptide, libérant ainsi le PS qui retrouve alors sa capacité à former de l’1O2. Trouver un couple PS/quencher adéquat reste un challenge en PDT. Les propriétés photophysiques particulières des caroténoïdes et leur aptitude à inhiber la production d’1O2 font de ces derniers des quenchers potentiellement utilisables pour l’élaboration de PMBs. Chez les plantes, les caroténoïdes (carotènes et xanthophylles) sont des pigments associés à la photosynthèse, qui ont deux rôles principaux : un rôle de collecteur de lumière et un rôle photoprotecteur en protégeant le(s) système(s) photosynthétique(s) contre les dommages photooxydatifs liés à une exposition trop intense à la lumière. Ceci s’opère, entre autre, via le cycle des xanthophylles. Cette aptitude à capter de l’énergie présente un intérêt potentiel à ne pas négliger dans la perspective de la conception de PMB utilisables en thérapie photodynamique. Dans le cadre de cette thèse en co-tutelle avec la Faculté des Sciences de Bizerte nous avons ciblé les caroténoïdes présents dans trois fruits produits en Tunisie à savoir les kakis (Diospyros kaki L.), les abricots (Prunus armeniaca L.) et les pêches (Prunus persica L.) connus pour leur richesse globale en ces pigments. Divers procédés d’extractions ont été étudiés : (i) L’extraction de type Soxhlet par solvants organiques à pression atmosphérique, utilisée comme référence, (ii) l'extraction accélérée par solvant organique (ASE : Accelerated solvent Extraction) effectuée sous pression, enfin (iii) l'extraction par CO2 supercritique avec l’éthanol comme cosolvant. Pour ces deux derniers procédés, une approche par plan d’expériences (surfaces de réponses) a été utilisée pour identifier les facteurs clé et les conditions optimales d’extractions de divers caroténoïdes (pression, température, débit, % de cosolvant, temps, nombre de cycles). L'analyse par chromatographie liquide à haute performance couplée à la détection UV-Visible et à la spectrométrie de masse a ensuite permis l'identification et la quantification des caroténoïdes présents dans les extraits obtenus, permettant ainsi de comparer les profils caroténoïdiques propres à chaque fruit et les performances de chaque procédé d’extraction. Cette étude ayant révélé un profil caroténoïdique particulièrement intéressant chez le kaki par rapport aux autres fruits, une extraction et une purification des caroténoïdes de ce fruit par chromatographie liquide haute pression préparative a ensuite été effectuée afin de disposer d’une quantité suffisante de chaque caroténoïde, et parfois de leurs isomères conformationnels, en vue de l’étude de leurs propriétés photophysiques (absorption, émission de fluorescence, inhibition d’1O2) et de l’évaluation de leur intérêt potentiel en tant que quencher d’1O2 dans un édifice de type PM

Extraction, Identification and Photo-Physical Characterization of Persimmon (Diospyros kaki L.) Carotenoids

Carotenoid pigments were extracted and purified from persimmon fruits using accelerated solvent extraction (ASE). Eleven pigments were isolated and five of them were clearly identified as all-trans-violaxanthine, all-trans-lutein, all-trans-zeaxanthin all-trans-cryptoxanthin and all-trans-β-carotene. Absorption and fluorescence spectra were recorded. To evaluate the potential of 1O2 quenching of the purified carotenoids, we used a monocarboxylic porphyrin (P1COOH) as the photosensitizer to produce 1O2. The rate constants of singlet oxygen quenching (Kq) were determined by monitoring the near-infrared (1270 nm) luminescence of 1O2 produced by photosensitizer excitation. The lifetime of singlet oxygen was measured in the presence of increasing concentrations of carotenoids in hexane. Recorded Kq values show that all-trans-β-cryptoxanthin, all-trans-β-carotene, all-trans-lycopene and all-trans-zeaxanthin quench singlet oxygen in hexane efficiently (associated Kq values of 1.6 × 109, 1.3 × 109, 1.1 × 109 and 1.1 × 109 M−1·s−1, respectively). The efficiency of singlet oxygen quenching of β-cryptoxanthin can thus change the consideration that β-carotene and lycopene are the most efficient singlet oxygen quenchers acting as catalysts for deactivation of the harmful 1O2

Optimization of carotenoids extraction from persimmon (Diospyros kaki L.), apricot (Prunus armeniaca L.) and peach (Prunus persica L.) : Photophysical study for photodynamic therapy (PDT) application

La thérapie photodynamique (PDT) est une technique utilisée cliniquement pour traiter certaines maladies de la peau, la dégénérescence maculaire liée à l’âge et certains types de cancer. Elle fait intervenir trois composants : une molécule photosensible ou photosensibilisateur (PS), la lumière et l’oxygène. Après administration du PS, celui-ci va se localiser plus ou moins sélectivement dans les zones tumorales où il est alors activé par irradiation lumineuse à une longueur d’onde et une puissance données. Ceci engendre la formation d’espèces réactives de l’oxygène (ROS) très réactives, dont l'oxygène singulet1 O2, qui entraînent la destruction des tissus tumoraux par nécrose ou apoptose. Afin d’améliorer la sélectivité du traitement, différentes pistes sont actuellement exploitées dont l’élaboration de « photodynamic molecular beacons » (PMB). Dans un PMB, le photosensibilisateur (PS) est associé via un peptide à un inhibiteur 1O2, appelé quencher. Ce quencher inhibe la formation d’1O2 tant que le composé n’a pas atteint sa cible. Une fois la zone cancéreuse atteinte, des enzymes spécifiques clivent le peptide, libérant ainsi le PS qui retrouve alors sa capacité à former de l’1O2. Trouver un couple PS/quencher adéquat reste un challenge en PDT. Les propriétés photophysiques particulières des caroténoïdes et leur aptitude à inhiber la production d’1O2 font de ces derniers des quenchers potentiellement utilisables pour l’élaboration de PMBs. Chez les plantes, les caroténoïdes (carotènes et xanthophylles) sont des pigments associés à la photosynthèse, qui ont deux rôles principaux : un rôle de collecteur de lumière et un rôle photoprotecteur en protégeant le(s) système(s) photosynthétique(s) contre les dommages photooxydatifs liés à une exposition trop intense à la lumière. Ceci s’opère, entre autre, via le cycle des xanthophylles. Cette aptitude à capter de l’énergie présente un intérêt potentiel à ne pas négliger dans la perspective de la conception de PMB utilisables en thérapie photodynamique. Dans le cadre de cette thèse en co-tutelle avec la Faculté des Sciences de Bizerte nous avons ciblé les caroténoïdes présents dans trois fruits produits en Tunisie à savoir les kakis (Diospyros kaki L.), les abricots (Prunus armeniaca L.) et les pêches (Prunus persica L.) connus pour leur richesse globale en ces pigments. Divers procédés d’extractions ont été étudiés : (i) L’extraction de type Soxhlet par solvants organiques à pression atmosphérique, utilisée comme référence, (ii) l'extraction accélérée par solvant organique (ASE : Accelerated solvent Extraction) effectuée sous pression, enfin (iii) l'extraction par CO2 supercritique avec l’éthanol comme cosolvant. Pour ces deux derniers procédés, une approche par plan d’expériences (surfaces de réponses) a été utilisée pour identifier les facteurs clé et les conditions optimales d’extractions de divers caroténoïdes (pression, température, débit, % de cosolvant, temps, nombre de cycles). L'analyse par chromatographie liquide à haute performance couplée à la détection UV-Visible et à la spectrométrie de masse a ensuite permis l'identification et la quantification des caroténoïdes présents dans les extraits obtenus, permettant ainsi de comparer les profils caroténoïdiques propres à chaque fruit et les performances de chaque procédé d’extraction. Cette étude ayant révélé un profil caroténoïdique particulièrement intéressant chez le kaki par rapport aux autres fruits, une extraction et une purification des caroténoïdes de ce fruit par chromatographie liquide haute pression préparative a ensuite été effectuée afin de disposer d’une quantité suffisante de chaque caroténoïde, et parfois de leurs isomères conformationnels, en vue de l’étude de leurs propriétés photophysiques (absorption, émission de fluorescence, inhibition d’1O2) et de l’évaluation de leur intérêt potentiel en tant que quencher d’1O2 dans un édifice de type PMBPhotodynamic therapy (PDT) is a clinically used technique for treating skin diseases, age-relatedmacular degeneration but mainly some types of cancer. PDT involves three components: a photosensitive molecule named photosensitizer (PS), light and oxygen. After administration of the PS, this one will be located more or less selectively in tumoral regions where it is activated by light irradiation at appropriate wavelength and power. This leads to the formation of highly reactive and cytotoxic reactive oxygen species (ROS), especially singlet oxygen, resulting in the destruction of the tumor by necrosis or apoptosis. To improve the treatment selectivity, different strategies are being exploited, one of which is the development of "photodynamic molecular beacons" (PMB). In PMB the photosensitizer is linked via a peptide to an inhibitor of 1O2 (quencher). This quencher inhibits the formation of 1O2 as long as the compound has not reached its target, namely cancer cells. In order to inhibit the toxicity of the PS in non-target cells and restore toxicity only close to the biological target, it is necessary to find an adequate PS/quencher couple. This remains a challenge for PDT. Carotenoids are interesting candidates due to their specific photophysical properties and ability to inhibit 1O2, which makes them potential quenchers for building PMBs. In plants, carotenoids (carotenes and xanthophylls) are pigments involved in the photosynthesis, in which they play two main roles: a light collecting role and a protecting role by preserving the photosynthetic systems against photoxydative damages induced by a too intense light exposure. This protection can for instance occur via the well-known xanthophylls cycle. This capacity to catch energy presents a potential interest that should not be neglected in the framework of the design of PMBs usable in photodynamic therapy. Within the framework as part of this PhD thesis in Cotutelle with the Faculty of Sciences of Bizerte, we focused on carotenoids from three fruits produced in Tunisia: persimmon (Diospyros kaki L.), apricot (Prunus armeniaca L.) and peache (Prunus persica L.), known for their global richness in these natural pigments. Three extraction processes were investigated: (i) the Soxhlet extraction based on the use of organic solvent at atmospheric pressure and used as reference, (ii) the accelerated solvent extraction (ASE) using organic solvent under high pressure, and (iii) the supercritical fluid extraction (SFE) using supercritical CO2 and ethanol as cosolvent. For these two last processes, a design of experiments (Surface Response Design) was used to identify the key factors and optimal extraction conditions of various carotenoids (pressure, temperature, flow, % cosolvent, time, number of cycles). Then, HPLC-PDA coupled with mass spectrometry (MS) enabled the identification and quantification of carotenoids from the extracts. Thus it was possible to compare the profiles in carotenoids content from each fruit as well as the performances of each extraction process. This study showed that the carotenoidic profile in the persimmon was the most interesting as compared to the profiles in the two other fruits. Extraction and purification of the carotenoids from persimmon by preparative high pressure liquid chromatography were then performed in order to have a sufficient amount of each carotenoid and sometimes of their conformational isomers. We finally performed a study of their photophysical properties (absorption, fluorescence emission, 1O2 inhibition) in order to evaluate their potential as 1O2 quencher in molecular construction such as a PM

Extraction, Identification and Photo-Physical Characterization of Persimmon (Diospyros kaki L.) Carotenoids

International audienceCarotenoid pigments were extracted and purified from persimmon fruits using accelerated solvent extraction (ASE). Eleven pigments were isolated and five of them were clearly identified as all-trans-violaxanthine, all-trans-lutein, all-trans-zeaxanthin all-trans-cryptoxanthin and all-trans-β-carotene. Absorption and fluorescence spectra were recorded. To evaluate the potential of ¹O₂ quenching of the purified carotenoids, we used a monocarboxylic porphyrin (P1COOH) as the photosensitizer to produce ¹O₂. The rate constants of singlet oxygen quenching (Kq) were determined by monitoring the near-infrared (1270 nm) luminescence of ¹O₂ produced by photosensitizer excitation. The lifetime of singlet oxygen was measured in the presence of increasing concentrations of carotenoids in hexane. Recorded Kq values show that all-trans-β-cryptoxanthin, all-trans-β-carotene, all-trans-lycopene and all-trans-zeaxanthin quench singlet oxygen in hexane efficiently (associated Kq values of 1.6 × 10⁸, 1.3 × 10⁸, 1.1 × 10⁸ and 1.1 × 10⁸ M-1·s-1, respectively). The efficiency of singlet oxygen quenching of β-cryptoxanthin can thus change the consideration that β-carotene and lycopene are the most efficient singlet oxygen quenchers acting as catalysts for deactivation of the harmful ¹O₂

Response surface methodology applied to Supercritical Fluid Extraction (SFE) of carotenoids from Persimmon (Diospyros kaki L.)

International audienceSupercritical carbon dioxide with ethanol as co-solvent was used to extract carotenoids from persimmon fruits (Diospyros kaki L.). Based on a response surface methodology (RSM), a predicting model describing the effects of CO2 temperature, pressure, flow rate, ethanol percentage and extraction time was set up for each of the four carotenoids of interest. The best extraction yields in our experimental domain were found at 300 bars, 60 degrees C, 25% (w/w) ethanol, 3 mL/min flow rate and 30 min for xanthophylls (alltrans- lutein, all-trans-zeaxanthin and all-trans-beta-cryptoxanthin). The yields were 15.46 +/- 0.56, 16.81 +/- 1.74 and 33.23 +/- 2.91 mu g/g of persimmon powder for all-trans-lutein, all-trans-zeaxanthin and all-trans-beta-cryptoxanthin, respectively. As a non-oxygenated carotenoid, all-trans-beta-carotene was better extracted using 100 bars, 40 degrees C, 25% (w/w) ethanol, 1 mL/min flow rate and 30 min extraction time, with an extraction yield of 11.19 +/- 0.47 mu g/g of persimmon powder

Recovery of anthocyanins from passion fruit epicarp for food colorants: extraction process optimization and evaluation of bioactive properties

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.Fundação para a Ciência e a Tecnologia | UIDB/00690/202

A Lab-Made E-Nose-MOS Device for Assessing the Bacterial Growth in a Solid Culture Medium

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