Development of water-in-oil emulsions as delivery vehicles and testing with a natural antimicrobial extract

Water-in-oil (W/O) emulsions have high potential for several industrial areas as delivery systems of hydrophilic compounds. In general, they are less studied than oil-in-water (O/W) systems, namely in what concerns the so-called fluid systems, partly due to problems of instability. In this context, this work aimed to produce stable W/O emulsions from a natural oil, sweet almond oil, to be further tested as vehicles of natural hydrophilic extracts, here exemplified with an aqueous cinnamon extract. Firstly, a baseW/O emulsion using a high-water content (40/60, v/v) was developed by testing di erent mixtures of emulsifiers, namely Tween 80 combined with Span 80 or Span 85 at di erent contents. Among the tested systems, the one using a 54/46 (v/v) Span 80/Tween 80 mixture, and subjected to 12 high-pressure homogenizer (HPH) cycles, revealed to be stable up to 6 months, being chosen for the subsequent functionalization tests with cinnamon extract (1.25–5%; w/v; water-basis). The presence of cinnamon extract leaded to changes in the microstructure as well as in the stability. The antimicrobial and antioxidant analysis were evidenced, and a sustained behavior compatible with an extract distribution within the two phases, oil and water, in particular for the higher extract concentration, was observed.Base Funding—UIDB/00690/2020 of CIMO—Mountain Research Center—funded by national funds through FCT/MCTES (PIDDAC). Base Funding—UIDB/50020/2020 of the Associate Laboratory LSRE-LCM—funded by national funds through FCT/MCTES (PIDDAC).info:eu-repo/semantics/publishedVersio

Evaluation of saponin-rich extracts as natural alternative emulsifiers: A comparative study with pure Quillaja Bark saponin

Due to synthetic surfactants' environmental impact, their replacement by natural alternatives has gained relevance, with saponins emerging as sustainable approaches. In this work, three saponin-rich extracts from different sources (Tribulus terrestris (TT), Trigonella foenum-graecum (FG), and Ruscus aculeatus (RA)) were tested as emulsifiers, and their performance compared with Quillaja Bark saponin (PS). Characterisation comprised FTIR, solubility studies, CMC assays, and emulsifying properties (emulsifying capacity (EC) and foaming capacity (FC)). For all samples, solubility assays indicated high solubility in water and low in apolar solvents (e.g., n-hexane), compatible with their O/W emulsifier character. In general, the saponin content ruled extracts' performance (PS > TT > FG > RA). EC values (without pH adjustment) were found to be 82.5, 55.0, 47.5, 36.3%, respectively. When pH changed for 7 and 9, a shift in FG and RA order was observed. The pseudo-ternary diagrams, constructed to map emulsion's composition zones, indicate the formation of single-phase systems in the region of low oil and high extract content. Except for RA extract, gel samples were formed, which are interesting technological solutions for several applications. Among the studied samples, and in alternative to PS, TT extract showed the best performance.This work was financially supported by: Base Funding – UIDB/00690/2020 of CIMO – Centro de Investigação de Montanha – funded by national funds through FCT/MCTES (PIDDAC), Base Funding – UIDB/50020/2020 of the Associate Laboratory LSRE-LCM – funded by national funds through FCT/MCTES (PIDDAC), and project AIProcMat@ N2020 – NORTE-01-0145-FEDER 000006 supported by NORTE 2020 under the Portugal 2020 Partnership Agreement, through ERDF. National funding by FCT, Foundation for Science and Technology, through the individual research Grant 2020.05564. BD of Tatiana La Banca Schreiner. FCT, PI, through the institutional scientific employment program-contract for I.P. Fernandes contract through the celebration of program-contract foreseen in No. 4, 5 and 6 of article 23º of Decree-Law No. 57/2016, of 29th August, amended by Law No. 57/ 2017, of 19th July.info:eu-repo/semantics/publishedVersio

Development of chitosan microspheres through a green dual crosslinking strategy based on tripolyphosphate and vanillin

Microencapsulation procedures have recently focused attention on designing novel mi-crospheres via green synthesis strategies. The use of chitosan (CS) as an encapsulating material has increased interest due to its unique bioactive properties and the various crosslinking possibilities offered by their functional groups. The consolidation of the microspheres by physical crosslinking using sodium tripolyphosphate (TPP) combined with chemical crosslinking using vanillin (VA) open new opportunities in the framework of green dual crosslinking strategies. The developed strategy, a straightforward technique based on an aqueous medium avoiding complex separa-tion/washing steps, offers advantages over the processes based on VA, mostly using water-in-oil emulsion approaches. Thus, in this work, the combination of TPP crosslinking (3, 5, and 10 wt.%) via spray-coagulation technique with two VA crosslinking methods (in situ and post-treatment using 1 wt.% VA) were employed in the preparation of microspheres. The microspheres were characterized concerning morphology, particle size, physicochemical properties, thermal stability, and swelling behavior. Results revealed that the combination of 5 wt.% TPP with in situ VA crosslinking led to microspheres with promising properties, being an attractive alternative for natural bioactives encapsulation due to the green connotations associated with the process.Financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020). National funding by the FCT—Foundation for Science and Technology, through the institutional scientific employment program—contract with I.P.F. Further support was obtained through the Valor Natural project (Mobilized Project Norte-01-0247-FEDER-024479) and the GreenHealth project (Norte-01- 0145-FEDER-000042).info:eu-repo/semantics/publishedVersio

Saponin-based natural nanoemulsions as alpha-tocopherol delivery systems for dermal applications

Nanoemulsions can be produced using simple methods and compounds from natural sources. They can increase water dispersibility and bioavailability and optimise active ingredient dispersion in particular skin layers. Lipophilic compounds of the vitamin E family (tocopherols and tocotrienols) are well-known for their high antioxidant activity and capacity to protect the skin from oxidative stress. In this context, oil-in-water (o/w) nanoemulsions with and without α-tocopherol (Vitamin E, VE) were formulated with two emulsifier alternatives, Quillaja saponin (QS), and a combination of QS with Tribulus terrestris (QSTT) (50/50, w/w). The emulsions were evaluated concerning stability, microstructure, droplet size, colour attributes, encapsulation efficiency, UV photostability, antioxidant activity, and in vitro permeation studies to assess the delivery potential. Results showed highly stable systems, with round-shape droplets of 80–121 nm size. QS and QSTT samples' colours were close to white and light brownish, respectively. The topical nano cream had the capacity to entrap VE, producing a protective effect from UV degradation, and very significant antioxidant activity, with IC50 values around 0.01 %wt. The skin permeation profiles showed the efficiency of the formulations in the delivery of VE, with permeabilities between 64 and 74 µg/cm2, while the control sample showed no VE permeation.info:eu-repo/semantics/publishedVersio

Spirulina (Arthrospira platensis) protein-rich extract as a natural emulsifier for oil-in-water emulsions: optimization through a sequential experimental design strategy

Spirulina (Arthrospira platensis) proteins have been proven to present emulsifying properties. In this work, a Spirulina protein-rich extract obtained by ultrasound extraction (SpE) was tested to stabilize oil-in-water (O/W) emulsions. For this purpose, a sequential experimental design strategy (Fractional Factorial Design (FFD) 24–1 followed by a Central Composite Rotatable Design (CCRD) 22)) was applied. The effect of four variables, SpE concentration, O/W weight ratio, pH and storage time, on emulsions’ zeta potential and number-mean droplet diameter was considered for the FFD 24–1, indicating SpE concentration and storage time as the relevant variables for the CCRD 22. According to zeta potential and number-mean droplet diameter evaluation, for the studied SpE concentration range (2–5 wt%), quite stable emulsions were obtained along the tested 30-days period. Even so, for 5%, visual inspection revealed extract segregation after 20-days. The optimal solution comprised 4 wt% of SpE, for an O/W weight ratio of 30/70 and a pH of 7.0 (number-mean droplet diameter of 55.66 nm and zeta potential of -43.83 mV). Overall, SpE has proven to be an excellent emulsifier, offering the potential to substitute animal-based proteins and synthetic emulsifiers. In addition, no signs of contamination by microorganisms were observed, suggesting that the SpE may also act as an antimicrobial agent.CIMO (Centro de Investigação de Montanha, Portugal) (UIDB/00690/2020), LSRE-LCM (Laboratory of Separation and Reaction Engineering – Laboratory of Catalysis and Materials, Portugal) (UIDB/50020/2020; UIDP/50020/2020), and ALiCE (Associate Laboratory in Chemical Engineering, Portugal) (LA/P/0045/2020), funded by national funds through Fundação para Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Ensino Superior (FCT/MCTES) (PIDDAC). National funding by Fundação para a Ciência e a Tecnologia (FCT) (Portugal), P.I., through the institutional scientific employment program contract with A. Santamaria-Echart, L. Barros, and A. Fernandes. FCT for the PhD research grant of Samara Cristina da Silva (SFRH/BD/148281/2019) and Giovana Colucci (2021. 05215. BD).info:eu-repo/semantics/publishedVersio

New Trends in Natural Emulsifiers and Emulsion Technology for the Food Industry

The food industry depends on using different additives, which increases the search for effective natural or natural-derived solutions, to the detriment of the synthetic counterparts, a priority in a biobased and circular economy scenario. In this context, different natural emulsifiers are being studied to create a new generation of emulsion-based products. Among them, phospholipids, saponins, proteins, polysaccharides, biosurfactants (e.g., compounds derived from microbial fermentation), and organic-based solid particles (Pickering stabilizers) are being used or start to gather interest from the food industry. This chapter includes the basic theoretical fundamentals of emulsions technology, stabilization mechanisms, and stability. The preparation of oil-in-water (O/W) and water-in-oil (W/O) emulsions, the potential of double emulsions, and the re-emerging Pickering emulsions are discussed. Moreover, the most relevant natural-derived emulsifier families (e.g., origin, stabilization mechanism, and applications) focusing food applications are presented. The document is grounded in a bibliographic review mainly centered on the last 10-years, and bibliometric data was rationalized and used to better establish the hot topics in the proposed thematic

Development of functional finishes based on natural products for leather applications

Dupla diplomação com a Universidade Tecnológica e Federal do Paraná - UTFPRNanoemulsions are biphasic systems characterized by having droplets with nanometer size range, which confers them several advantages, such as high hydration capacity and increased bio-efficacy of the functionalities incorporated therein. In this context, the objective of this work was to develop a water-in-oil (W/O) nanoemulsion system based on natural compounds, like sweet almond oil and Cinnamomum zeylanicum aqueous extract, in order to produce a moisturizing and antimicrobial spray for leather application. Firstly, a systematic study was performed by testing different base formulations to establish the procedure for nanoemulsion preparation using a high-pressure homogenizer (HPH). A total of 16 base formulations were prepared by varying the W/O ratio and emulsifier composition. These samples were then analyzed by microscopic and visual analysis in order to evaluate the droplets size and morphology together with stability along the time. Based on these results, the best formulation revealed to be the system S4, corresponding to a W/O ratio of 40/60 (v/v), and Span 80/Tween 80 mixture (54/46 ratio, v/v) as emulsifier. Using this formulation, nanoemulsions functionalized with cinnamon at contents of 1.25%; 2.5%; 3.75%; 5% (w/v; water base) were prepared. Afterwards, these products, together with the base system, were characterized by Confocal Laser Scanning Microscopic (CLSM), color parameters, evaluated concerning the antimicrobial and antioxidant bioactivities, and stability. As results, CLSM confirmed the nature of the water-in-oil system, revealing also a change in the nanoemulsions microstructure due to the increase of cinnamon extract concentration. The color measurement evidenced a luminosity diminishing and a color variation to yellow and red as the extract content was increased. In addition, the formulations containing the cinnamon extract evidenced antimicrobial and antioxidant activity. The absence of bioactivity for the base nanoemulsion corroborated the effect of the cinnamon extract in the detected antimicrobial and antioxidant. Furthermore, for the antimicrobial activity, the formulations containing the extract presented a prolonged effect against E. coli and S. aureus bacteria, being detected similar inhibition zones for all the tested extract concentrations. Regarding the antioxidant activity, the rise in the extract concentration resulted in a relevant increase of this property. Finally, and according to the performed accelerated stability tests, a high stability against centrifugation for the base nanoemulsion was detected, evidencing that the presence of the extract contributes to the formulation instability. Beyond this, all the formulations showed high stability against thermal stress. From a general perspective, the results obtained are of great importance for the product design and development having in view the application as leather preservative and moisturizer, since the formulations presented antioxidant and antimicrobial activity, parameters that contribute to the protection and preservation of the shoes. In addition, their stability points for a good shelf life of these systems, being suitable for storage under commercialization conditions.As nanoemulsões são sistemas bifásicos constituídas por gotículas de tamanho nanométrico que lhe conferem várias vantagens, tais como alta capacidade de hidratação e a promoção de elevada bioeficácia dos princípios ativos incorporados. Neste contexto, o presente trabalho teve como objetivo desenvolver um sistema de nanoemulsões água-em-óleo (A/O) baseado em compostos naturais, óleo de amêndoas doces e extrato aquoso de Cinnamomum zeylanicum (canela), visando a produção de um spray com propriedades hidratantes e antimicrobianas destinado à aplicação no couro. Numa fase inicial deste trabalho procedeu-se a um estudo sistemático das condições de preparação e das formulações base, tendo estas sido produzidas utilizando um homogeneizador de alta pressão (HAP). No total produziram-se 16 sistemas base, onde se testaram diferentes razões A/O e composições de emulsionante. Seguidamente, estes sistemas foram caracterizados por análise microscópica e observação visual tendo por objetivo avaliar o tamanho da gotícula e a estabilidade ao longo do tempo de armazenamento. Com base nos resultados obtidos, verificou-se que o sistema S4 , o qual corresponde à utilização de uma razão A/O de 40/60 (v/v) e uma mistura de emulsionantes composta por Span 80/Tween 80 (razão 54/46, v/v), foi o que apresentou a melhor estabilidade. Na etapa seguinte este sistema base foi utilizado para a preparação de nanoemulsões funcionalizadas com diferentes teores de extrato de canela (1.25%; 2.5%; 3.75%; 5% (m/v; base água)). Posteriormente procedeu-se à sua caracterização, conjuntamente com o sistema base, através de Microscopia Confocal (MC), avaliação da cor e das atividades antimicrobiana e antioxidante e estabilidade. Os resultados obtidos através de MC permitiram confirmar a natureza da tipologia água-em-óleo, revelando também alterações da microestrutura das nanoemulsões à medida que o teor de extrato foi incrementado. A medição da cor evidenciou uma diminuição da luminosidade com o aumento da concentração de extrato, assim como uma variação da cor para amarelo e vermelho. Adicionalmente, as formulações contendo o extrato apresentaram atividade antimicrobiana e antioxidante, permitindo também observar a ausência de atividades para a emulsão base. Estes resultados mostraram assim que a manifestação destas atividades está relacionada com a incorporação do extrato. No caso da atividade antimicrobiana, identificou-se um efeito prolongado da atividade contra as bactérias E. coli e S. aureus, tendo sido detetadas zonas com o mesmo diâmetro de inibição. Em relação à análise antioxidante, o aumento da concentração do extrato resultou num incremento significativo desta atividade. Relativamente aos testes de estabilidade acelerados, a nanoemulsão base apresentou maior estabilidade à centrifugação, indicando que a presença do extrato contribui para a instabilidade das formulações. No que respeita ao stress térmico, verificou-se que todas as formulações apresentaram uma elevada estabilidade. De uma forma geral, considera-se que os resultados obtidos neste trabalho são de grande importância para o desenvolvimento de um produto destinado à aplicação no couro, dado que as formulações apresentaram atividade antioxidante e antimicrobiana, contribuindo para a proteção e preservação do calçado. Adicionalmente, os testes de estabilidade das formulações evidenciaram um produto com boa estabilidade às condições de armazenamento necessárias à sua comercialização.This work was financially supported by Associate Laboratory LSRE-LCM (UID/EQU/50020/2019) funded by national funds through FCT/MCTES (PIDDAC), and Foundation for Science and Technology (FCT, Portugal). CIMO (UID/AGR/00690/2019) through FEDER under Program PT2020. Also, this thesis was done in the context of FAMEST Mobilizer Project (POCI-01-0247-FEDER-024529) co-financed by COMPETE2020 through PT2020 and FEDER

Production of lignin Pickering stabilizers using lignin samples from the acetone fractionation process

Colloidal lignin particles (CLPs) as stabilizers of Pickering emulsions are a sustainable approach to replace synthetic emulsifiers in cosmetic emulsions. In this work, the effect of lignin samples from the acetone fractionation in the production of CLPs for Pickering emulsion stabilization was studied. The original samples and their fractions revealed different structural features, reflected in the CLPs properties, although, in general, all CLPs exhibited high potential as Pickering stabilizers

Ethosomes: an approach for bioactive plant extract preservation envisaging cosmetic applications

The present work is focused on upgrading the commercial potential of berry crop by-products by encapsulating them into liposomes to preserve their bioactivity. The extracts have been obtained with an ethanol-water mixture using ultrasound-assisted extraction, and the most promising ones were encapsulated in ethosome system. To achieve this goal, ethosomes were prepared using the cold method. Ethosomal suspensions were characterized concerning particle size distribution by laser dispersion, differential scanning calorimetry, infrared Fourier-transform spectroscopy, encapsulation efficiency, and morphological analysis using optical, scanning electron, and transmission electron microscopy. These results indicate that ethosomes are an appropriate method to encapsulate hydroethanolic bioactive plant bioresidue extracts and a good option to preserve them for further use in industrial applications, such as cosmetics. Future work will include optimizing the process and proof of concept by developing a cosmetic application.info:eu-repo/semantics/publishedVersio