In-depth phenolic characterization of iron gall inks by deconstructing representative Iberian recipes

UIDB/50006/2020 PTDC / QUI-OUT / 29925/2017Iron-gall ink is one of the most important inks in the history of western civilization. The deep black colour results from Fe3+ complexes with phenolic compounds available in gall extracts. Unfortunately, it induces the degradation of both ink and support over time. Furthermore, our knowledge of these complex molecular structures is limited. This work aims to overcome this gap, revealing essential information about the complex structures of these pigments and dyes that will create a breakthrough in the next generation of conservation treatments. It presents the first in-depth phenolic identification and quantification of extracts and inks, prepared with and without gum arabic (an essential additive in medieval recipes). Five representative Iberian recipes were selected and prepared. Their phenolic profile was analysed by HPLC–DAD and HPLC–ESI–MS, which revealed that the phenolic compounds present in higher concentration, in the gall extracts, are pentagalloylglucose and hexagalloylglucose (0.15 ± 0.01–32 ± 3 mg/mL), except for one recipe, in which gallic acid is the main phenolic. The influence of the ingredients is also discussed by deconstructing the recipes: extracts of additives as pomegranate peel and solvents used in the extraction of the galls (vinegar and white wine) were characterized.publishersversionpublishe

Valorization of agro-industrial wastes towards the production of rhamnolipids

In this work, oil mill wastewater (OMW), a residue generated during olive oil extraction, was evaluated as an inducer of rhamnolipid production. Using a medium containing as sole ingredients corn steep liquor (10%, v/v), sugarcane molasses (10%, w/v) and OMW (25%, v/v), Pseudomonas aeruginosa #112 produced 4.5 and 5.1 g of rhamnolipid per liter in flasks and reactor, respectively, with critical micelle concentrations as low as 13 mg/l. Furthermore, in the medium supplemented with OMW, a higher proportion of more hydrophobic rhamnolipid congeners was observed comparing with the same medium without OMW. OMW is a hazardous waste which disposal represents a serious environmental problem; therefore, its valorization as a substrate for the production of added-value compounds such as rhamnolipids is of great interest. This is the first report of rhamnolipid production using a mixture of these three agro-industrial by-products, which can be useful for the sustainable production of rhamnolipids.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI- 01-0145-FEDER-006684). The authors also thank the FCT for the financial support under the scope of the Project RECI/BBBEBI/ 0179/2012 (FCOMP-01-0124-FEDER-027462). E.J. Gudiña was supported by the Post-Doctoral fellowship CEB-BPD/01/2015/07 from the project UID/BIO/04469/2013, financed by FCT. A.I. Rodrigues was supported by the doctoral Grant SFRH/BD/111600/2015 provided by FCT

The Triumph of the blue in nature and in Anthropocene

This research was also supported by AgriFood XXI I&D&I project ( NORTE-01-0145-FEDER-000041 ) cofinanced by European Regional Development Fund (ERDF) , through the NORTE 2020 (Programa Operacional Regional do Norte 2014/2020); We thank Miriam Colaço for raising the question of the blue LASERS. Publisher Copyright: © 2022 The Author(s)Blue was the last color to be spread in Nature by the anthocyanins present in angiosperms, and the last color to be managed by Humans in Anthropocene. Blue also appears in a small number of algae, fungi, and bacteria, but these living beings have very little to do with the profusion of a natural blue hue. Humanity took many long years to figure out how to reproduce and use blue - the classic example of which is indigo dye, extracted from plants like the Indigofera tinctoria. However, even simple anthocyanins are not capable of achieving blue. Plants had to develop strategies to fix this color, mainly by intramolecular copigmentation in acylated anthocyanins and complexation with metals, as in metalloanthocyanins. Blue was absent in the first paleolithic cave paintings. Those depictions were made using reds, yellows, and blacks of all hues, but no blue. In addition, blue LEDs and LASERs came later after red and green. It was only at the end of the 20th century that genetic engineering was able to create blue flowers adapted to the markets to meet consumer demands. Food and beverage producers continue to look for a natural blue as an alternative to synthetic colorants. Blue remained a second-rate color in the West for a long time. Despite that fact, in many countries blue is now the preferred color. In this review we track the appearance of blue in Nature and in the Anthropocene.publishersversionpublishe

Polyphenol extraction by deep eutectic solvent for valorisation of portuguese green tea and their impact on chitosan-based films properties

The current demand for antioxidant active packaging, that is achieved by introducing antioxidants into food packaging material, is increasing due to both the unquestionable advantages compared to the addition of antioxidants directly to the food and the tendency to consume healthy and fresh products. When developing active packaging materials, research has been focused on natural and biodegradable polymers (such as polysaccharides like chitosan) containing polyphenol compounds (as bio preservative) in their formulation. Due to their rare solvation properties, the natural deep eutectic solvents (NADES), are considered good solvents to be used as an extraction medium of bioactive products. Moreover, the search for the use of ecological solvents for this field has intensified due to their acceptable toxicity profile and chemical diversity. The use of these inexpensive, non-volatile, and nonaqueous biodegradable solvents, complying with the Green Chemistry principles, could potentially improve the stability of the polyphenolic compounds allowing to retard food spoilage for packaging material, Catechins (components of green tea (GT)), a polyphenolic group known for its high value-added antioxidant properties, have been associated with health-promoting effects. In this sense, the incorporation of GT components for food application purposes and as active ingredient in packaging materials can be expected to improve food functionality and availability, while performing a dual role (antioxidant and antimicrobial agent) and possibly also having low-cost advantages. In this work, for the first time, a ternary deep eutectic solvent (ChCl/glycerol/lactic acid) was used as an environmentally friendly media for the extraction of polyphenolic compounds from green tea. The extraction solution was compared with traditional method and used to improve chitosan film properties. The casting method used to produce films with and without GT/NADES plasticizer. Transparent films were obtained and evaluated in terms of mechanical, water resistance, optical and microstructural properties. The results were compared with those obtained for chitosan films containing binary deep eutectic solvents (ChCl/glycerol and ChCl/lactic acid, with and without GT)) as plasticizers in their formulations.The work was supported through the project UIDB/50006/2020, funded by FCT/MCTES through national funds and by the AgriFood XXI I&D&I project (NORTE-01-0145-FEDER-000041 co-financed by European Regional Development Fund (ERDF), through the NORTE 2020. N Teixeira and Hiléia Souza thanks FCT for CEECIND/00025/2018/CP1545/CT0009 and PTDC/OCE-ETA/31250/2017 project respectively.info:eu-repo/semantics/publishedVersio

Achieving Complexity at the Bottom: Molecular Metamorphosis Generated by Anthocyanins and Related Compounds

Funding Information: This work was supported by the Associated Laboratory for Sustainable Chemistry, Clean Processes and Technologies LAQV through the national funds from UIDB/50006/2020 and UIDP/50006/2020 as well as the European Regional Development Fund within the Operational Programme “Science and Education for Smart Growth 2014–2020” under the Project CoE “National Center of Mechatronics and Clean Technologies” (BG05M2OP001-1.001-0008). N.B. is grateful to FCT for the contract CEECIND/00466/2017, D.S. for the doctoral grant (SFRH/BD/143369/2019), and L.C. for the research contract DL 57/2016/CP1334/CT0008. Publisher Copyright: © 2021 The Authors. Published by American Chemical Society.The concept of molecular metamorphosis is described. A molecule (flavylium cation) generates a sequence of other different molecules by means of external stimuli. The reversibility of the system allows for the flavylium cation to be recovered by other external stimuli, completing one cycle. Differently from supramolecular chemistry, molecular metamorphosis is not a bottom-up approach. All events occur at the bottom. The procedures to characterize the kinetics and thermodynamics of the cycles are summarized. They are based on direct pH jumps (addition of a base to the flavylium cation) and reverse pH jumps (addition of an acid to equilibrated solutions at higher pH values). Stopped flow is an indispensable tool to characterize these systems. The following metamorphic cycles will be described to illustrate the concept: (i) introducing the flavanone in the metamorphic system and illustrating the concept of a timer at the molecular level; (ii) response of the flavylium-based metamorphosis to light inputs and the write-lock-read-unlock-erase molecular system; (iii) a one-way cycle of direct-reverse pH jumps; (iv) interconversion of the flavylium cation with 2,2′-spirobis[chromene] derivatives; (v) 6,8 A-ring substituent rearrangements.publishersversionpublishe

Effects of ohmic heating on extraction of food-grade phytochemicals from of colored potato

The influence of ohmic heating (OH) through the application of moderate electric fields on phytochemical compounds recovery from colored potato (Solanum tuberosum L. var. Vitelotte) was studied. A BoxBehnken design was used to simultaneously assess the effects of operational parameters such as electric field strength, temperature and process time on the yields of anthocyanins and total phenolic recovery on pretreatment of potato samples. From the analysis of the model, electric field, temperature and time were shown to have independent and interactive effects on the values of extraction yields. Aqueous extraction of phytochemical compounds after pretreatments can be described by using a two-step model involving simultaneous washing and diffusion of the solutes from the samples. Results shows that electrical fields of low energy levels and thermal effects can be combined and optimized into a single step treatment on extraction of anthocyanins and phenolic compounds from vegetable tissues providing high recovery yields with a reduced treatment time, less energy consumption and with no utilization of organic solvents (green extraction).This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01- 0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145- FEDER-000004) funded by European Regional Development Fund under the scope of Norte2020 e Programa Operacional Regional do Norte. The authors Ricardo N. Pereira, H elder Oliveira and Rui M. Rodrigues also thank to FCT their financial grants with references SFRH/BPD/81887/2011, PD/BD/106062/2015 and SFRH/BD/110723/ 2015, respectively

Impact of grape pectic polysaccharides on anthocyanins thermostability

The impact of grape pectic polysaccharides on malvidin-3-O-β-d-glucoside thermostability was evaluated in model solutions. Pectic polysaccharides richer in homogalacturonan domains, with less neutral sidechains (chelator fraction) showed higher binding with malvidin-3-O-β-d-glucoside, by 1H NMR (Ka=505 M-1). Binding affinity with water soluble extract was estimated to be 10-fold lower, possibly due to the presence of neutral branched regions and more compacted structure, hampering the binding. Hydrophobic domains, such as rhamnogalacturonans-I domains in acid soluble polysaccharides, may participate in the formation of complexes with malvidin-3-O-β-d-glucoside. The thermostability of anthocyanin-polysaccharides complexes was evaluated at different temperatures, assessing anthocyanins degradation by HPLC-DAD. Polysaccharides showed to improve anthocyanin thermostability, with chelator and acid extract having the highest impact at lowest temperatures. Electrostatic interactions, additionally stabilized by hydrophobic effect contribute to the anthocyanin-polysaccharides binding and to the consequent thermostabilization. The protection provided by grape pectic polysaccharides foresees innovative anthocyanin food products with improved thermostability and colour features.publishe

Autonomous Navigation System for a Delivery Drone

The use of delivery services is an increasing trend worldwide, further enhanced by the COVID pandemic. In this context, drone delivery systems are of great interest as they may allow for faster and cheaper deliveries. This paper presents a navigation system that makes feasible the delivery of parcels with autonomous drones. The system generates a path between a start and a final point and controls the drone to follow this path based on its localization obtained through GPS, 9DoF IMU, and barometer. In the landing phase, information of poses estimated by a marker (ArUco) detection technique using a camera, ultra-wideband (UWB) devices, and the drone's software estimation are merged by utilizing an Extended Kalman Filter algorithm to improve the landing precision. A vector field-based method controls the drone to follow the desired path smoothly, reducing vibrations or harsh movements that could harm the transported parcel. Real experiments validate the delivery strategy and allow to evaluate the performance of the adopted techniques. Preliminary results state the viability of our proposal for autonomous drone delivery.Comment: 12 pages, 15 figures, extended version of an paper published at the XXIII Brazilian Congress of Automatica, entitled "Desenvolvimento de um drone aut\^onomo para tarefas de entrega de carga

Behind the Scenes of Anthocyanins-From the Health Benefits to Potential Applications in Food, Pharmaceutical and Cosmetic Fields

Anthocyanins are widespread and biologically active water-soluble phenolic pigments responsible for a wide range of vivid colours, from red (acidic conditions) to purplish blue (basic conditions), present in fruits, vegetables, and coloured grains. The pigments' stability and colours are influenced mainly by pH but also by structure, temperature, and light. The colour-stabilizing mechanisms of plants are determined by inter- and intramolecular co-pigmentation and metal complexation, driven by van der Waals, π-π stacking, hydrogen bonding, and metal-ligand interactions. This group of flavonoids is well-known to have potent anti-inflammatory and antioxidant effects, which explains the biological effects associated with them. Therefore, this review provides an overview of the role of anthocyanins as natural colorants, showing they are less harmful than conventional colorants, with several technological potential applications in different industrial fields, namely in the textile and food industries, as well as in the development of photosensitizers for dye-sensitized solar cells, as new photosensitizers in photodynamic therapy, pharmaceuticals, and in the cosmetic industry, mainly on the formulation of skin care formulations, sunscreen filters, nail colorants, skin & hair cleansing products, amongst others. In addition, we will unveil some of the latest studies about the health benefits of anthocyanins, mainly focusing on the protection against the most prevalent human diseases mediated by oxidative stress, namely cardiovascular and neurodegenerative diseases, cancer, and diabetes. The contribution of anthocyanins to visual health is also very relevant and will be briefly explored

Catechol versus carboxyl linkage impact on DSSC performance of synthetic pyranoflavylium salts

co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER - 007265). FCT/MCTES is acicnowledged for Project PTDC/QEQ-QFI/1971/2014, grants PD/BD/135087/2017 (ALP), SFRH/BD/136556/2018 (VG) and a research FCT contract (LC).Anthocyanins are the main polyphenolic dyes found in young red wines, which are transformed into more stable structures such as pyranoanthocyanins, during wine ageing and maturation. While anthocyanins practically lose their red color between pH 1 and 5, as a result of the formation of colorless hemiketals, pyranoanthocyanins practically do not change their color intensity. For that they constitute a photosensitizer family with great potential for bio-inspired dye-sensitized solar cells (DSSCs). In this work, a series of pyranoanthocyanin derivatives were designed, synthesized and applied for the first time as dye sensitizers in DSSCs. A relation was established between dye structure and cell efficiency. Specifically, the influence of different linker units, carboxyl and catechol, was studied in terms of their influence in the various parameters related to DSSC efficiency. The presence of the catechol unit was shown to be essential for efficient electron injection of the dye into the TiO2 semiconductor, since carboxylic units showed a deleterious effect in electron injection due to their electron withdrawing character. An overall efficiency of 1.15% was obtained for the best performing compound, 10-catecholpyrano-3′,4’,5,7-tetrahydroxyflavylium, with no further optimization.authorsversionpublishe