Effect of temperature, pH and ionic strength on hydroxyapatite stabilised Pickering emulsions produced in batch and continuous mode

Oil-in-water (O/W) Pickering emulsions are attracting attention as carriers of lipophilic active compounds with clear advantages over traditional systems. Having in view their effective use it is important to study their stability against environmental stresses impacting manufacture, storage, and application conditions. In this work, hydroxyapatite nanoparticles (n-HAp) Pickering emulsions produced in continuous mode using a mesostructured reactor (average size ~ 7, 11 and 18 μm) and in batch mode using a rotor–stator device (average size ~ 18 μm) were studied concerning their behaviour at different temperatures (5–90 ºC), pH (2–10) and ionic strength (0–500 mM), conditions with relevance for food applications. Droplet size, morphology, and zeta-potential were analysed after 1 and 7 days under storage. In general, and despite the droplet size, the n-HAp Pickering emulsions were stable within the tested ionic strength range, at relatively high pH environments (6–10), and at temperatures up to 70 ºC. Pickering emulsions undergo complete phase separation at very low pH (2) due to n-HAp particle's disruption. A clear tendency to aggregation and coalescence was observed for high temperatures (70–90 ºC). Results indicate no significant differences related to the used production method. From an industrial perspective, this work also corroborates that the scale-up to a continuous process using a mesostructured reactor, NETmix, from a batch laboratorial process is feasible without impacting stability.This work was financially supported by LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), and UIDB/00690/2020 (CIMO) funded by national funds through FCT/ MCTES (PIDDAC). Andreia Ribeiro acknowledges her PhD fellowship funded by Project NORTE-08–5369-FSE-000028, supported by N2020, under PT2020, through ESF. Authors thank Fluidinova S.A. for providing samples of nanoXIM-CarePaste.info:eu-repo/semantics/publishedVersio

Continuous production of hydroxyapatite Pickering emulsions using a mesostructured reactor

Emulsions are used in a wide range of applications, including food and cosmetics. Nowadays, the demand for sustainable products has increased with Pickering emulsions emerging as clean alternatives. To achieve the industrial implementation of Pickering emulsions, continuous production and less intensive energy devices are required. In this context, a mesostructured reactor based on an innovative static mixer, NETmix, was tested to produce Pickering emulsions from a previously developed formulation in batch mode. The effect of the number of cycles (2–35) and Reynolds number (200–500), parameters that influence the residence time and the quality of mixing, on the Pickering emulsion properties (average droplet size, droplet morphology, and stability) was studied. The obtained results pointed out the feasibility of using NETmix to produce Pickering emulsions. It is a versatile technique to control in a tailor-made way the droplet size and generate small droplets at short times. Results show a decrease of the droplet size with increasing number of cycles and Reynolds. Under the tested conditions, stable dispersions with droplet size of ∼7 μm were produced using 17 cycles and Re = 400. Microscopy images show an oil core and nano-hydroxyapatite shell morphology.This work was financially supported by: Base Funding - UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC), and Base Funding - UIDB/00690/2020 of CIMO - Centro de Investigação de Montanha - funded by national funds through FCT/MCTES (PIDDAC). Andreia Ribeiro acknowledges her PhD fellowship funded by Project NORTE-08-5369-FSE- 000028, supported by N2020, under PT2020, through ESF. Authors thank Fluidinova S.A. for providing nanoXIM-CarePaste, and the Centro de Materiais da Universidade do Porto (CEMUP) and Instituto de Investigação e Inovação em Saúde (i3S) for the services provided with cryo-SEM and CLSM analysis, respectively.info:eu-repo/semantics/publishedVersio

Development of water-in-oil pickering emulsions from sodium oleate surface-modified nano-hydroxyapatite

The stabilisation of water-in-oil (W/O) Pickering emulsions is still a challenge for the scientific community. In this work, sodium oleate (SO) surface modified nano-hydroxyapatite (n-HAp) particles were produced and tested as W/O stabilisers. The modified n-HAp particles presented a wettability dependent on the used SO content, switching from hydrophilic (initial state) to hydrophobic (one SO layer) and back to hydrophilic (two SO layers). The Pickering emulsions produced with the particles holding one SO layer (contact angle ~90 ◦) showed their tight adsorption at the water-oil interface (confocal analysis), and maintained the stability up to 15 days. Overall this work provides new developments in the field of W/O Pickering emulsions, a topic less studied than O/W, opening new avenues for several applications.This work was financially supported by: Base- UIDB/50020/2020 and Programmatic- UIDP/50020/2020 Funding of LSRE-LCM, funded by national funds through FCT/MCTES (PIDDAC), and Base Funding - UIDB/00690/2020 of CIMO - Centro de Investigação de Montanha - funded by national funds through FCT/MCTES (PIDDAC). Andreia Ribeiro acknowledges her PhD fellowship funded by Project NORTE-08-5369-FSE-000028, supported by N2020, under PT2020, through ESF. Authors thank Fluidinova S.A. for providing samples of nanoXIM-102Paste.info:eu-repo/semantics/publishedVersio

Nanohydroxyapatite (n-HAp) as a pickering stabilizer in oil-in-water (O/W) emulsions: a stability study

Surfactant-free emulsions, such as Pickering emulsions, have been gaining an increased interest. They constitute green alternatives to the current industrial practices in emulsion technology finding diverse technological uses. In this work, nano-hydroxyapatite (n-HAp) was tested as an oil-in-water (O/W) Pickering stabilizer using a chemical system comprising sunflower oil at different O/W ratios (10/90 to 60/40) and n-HAp at concentrations ranging from 0.5 to 15 wt%. The produced emulsions were characterized, and stability evaluated over a two-month period. Based on the results achieved for the 20/80 series, a model to predict the emulsion stability taking into account the O/W ratio, total solids content, droplet diameter, and n-HAp dimensions, was developed. Cryo-SEM evidenced the attachment of n-HAp particles at the oil surface (oil core-n-HAp shell morphology), corroborating their role as Pickering stabilizers. The experimental results, versus the predicted results were compared using a ternary phase diagram, which evidenced the formation of three zones (unstable, stable and gel) depending on the used O/W ratio and n-HAp concentration. Moreover, the comparison of the predicted with the obtained experimental data validated the model predictability.This work was financially supported by: Associate Laboratory LSRELCM - UIDB/50020/2020 - funded by national funds through FCT/ MCTES (PIDDAC). To Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CIMO (UIDB/00690/2020). Andreia Ribeiro acknowledges her PhD fellowship funded by Project NORTE-08-5369-FSE-000028, supported by N2020, under PT2020, through ESF.info:eu-repo/semantics/publishedVersio

Moringa oleifera L. screening: SFE-CO2 optimisation and chemical composition of seed, leaf, and root extracts as potential cosmetic ingredients

Moringa oleifera L. tree (Mo) has emerged as a rich alternative source of bioactive compounds to design cosmetic formulations. Supercritical carbon dioxide fluid extraction (SFE-CO2) was successfully applied on the screening of Mo seed, leaf, and root extracts. The extraction yield was evaluated by response surface methodology (RSM), for pressure and temperature ranges of 117–273 bar and 41–60 C, respectively, using a design of experiments (DOE). The pressure significantly affected the results (a = 0.05), with the highest extraction efficiency obtained at conditions above 195 bar. The extracts’ composition, evaluated by gas chromatography-mass spectrometer (GC-MS), revealed an increasing correlation between the pressure, total extract solubility, and mass of extract at a constant temperature, due to the higher extraction yield. Seed extracts presented more than 80% of oleic acid in relative composition (8.04 mgcompound gplantpart -1). Leaf extracts performed well for the obtainment of linolenic acid (>20%; 3.10 mg g-1), nonacosane (>22%; 0.46 mg g-1), and -tocopherol (>20%; 0.21 mg g-1). Mo root resulted in higher relative composition for sterol molecules, despite its very low affinity with CO2. The most promising bioactive compounds, oleic acid and -tocopherol, were more abundant when operating at 250 bar at 45 C and 195 bar at 55 C, for Mo seed and leaf SFE-CO2 extracts, respectively.This work was financially supported by LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), UIDB/00690/2020 and UIDP/00690/2020 (CIMO) and LA/P/0007/2021 (SusTEC), funded by national funds through the Fundação para a Ciência e Tecnologia FCT/MCTES (PIDDAC). Júlia Cristiê Kessler acknowledges her PhD scholarship (ref. 2020.06656.BD) from FCT.info:eu-repo/semantics/publishedVersio

In vitro digestion and bioaccessibility studies of vitamin E-loaded nanohydroxyapatite pickering emulsions and derived fortified foods

Vitamin E is a lipophilic vitamin playing an essential role in human health. Due to oxidative instability, it presents fast degradation and bioactivity loss. In this study, vitamin E-loaded Pickering emulsions stabilized by nano-hydroxyapatite (n-HAp) were produced using a static mixer (NETmix), a technique enabling continuous production and droplet size tailoring. Thus, oil-in-water (O/W) emulsions containing vitamin E at a content of 1mg/mL were produced with different droplet sizes (7.53, 11.56 and 17.72m) using an O/W ratio of 20/80 (v/v). Their stability during in vitro gastrointestinal digestion and vitamin E bioaccessibility were investigated. It was observed that n-HAp particles disrupt in the stomach and subsequently aggregate as random calcium phosphates in the small intestine, leading to low vitamin E bioaccessibility due to oil entrapment. The emulsion showing the highest vitamin E bioaccessibility (3.29±0.57%, sample with the larger average droplet size) was used to produce fortified gelatine and milk, resulting in an increased bioaccessibility (10.87±1.04% and 18.07±2.90%, respectively). This fact was associated with the presence of macronutrients and the lower n-HAp content. Overall, n-HAp Pickering emulsions offer advantages for vitamin E encapsulation directed to fortified foods development, a process able to be extended to other lipophilic vitamins.This work was financially supported by Base Funding -UIDB/50020/2020 of the Associate Laboratory LSRE-LCM -funded by national funds through FCT/MCTES (PIDDAC), Base Funding -UIDB/00690/2020 of CIMO -funded by national funds through FCT/MCTES (PIDDAC), and Base Funding -UIDB/04469/2020 of the CEB funded by national funds through FCT. Andreia Ribeiro acknowledges her PhD fellowship funded by Project NORTE-08-5369-FSE-000028, supported by N2020, under PT2020, through ESF, and Raquel F. Goncalves acknowledges the Foundation for Science and Technology (FCT) for their fellowship (SFRH/BD/140182/2018). Authors thank Fluidinova S.A. for providing samples of nanoXIM-CarePaste and Instituto de Investigacao e Inovacao em Saude (i3S) for the services provided with CLSM analysis.info:eu-repo/semantics/publishedVersio

Chemical and organoleptic properties of bread enriched with Rosmarinus officinalis L.: the potential of natural extracts obtained through green extraction methodologies as food ingredients

The potential of R. officinalis L. (RO) extracts as a source of aromas was accessed by hydrodistillation (HD) and supercritical fluid extraction using carbon dioxide (SFE-CO2), followed by a series of analysis: quantification by GC-MS, sensory perception and description, and cytotoxicity against Vero cells. The extracts shown abundancy of α-pinene, eucalyptol, S-verbenone and camphor, contributing for the green, fresh, citric, and woody as main sensory notes. The odour threshold (ODT) value (less than 3.0 × 10 3 μg⋅mL 1) and the cytotoxic potential (ca. 220 μg∙mL 1) defined the concentration range for food application. The most promising extract was added to bread doughs and the final volatile profile was characterised by GC-MS through HS-SPME over time. Among the 34 compounds found, furfural showed an evident contribution in the bread crust aroma, which persisted over four hours of storage, contributing to a pleasant bread fragrance according to the evaluators. This study aims to represent a stepping stone for the use of natural aromas as ingredients for the development of innovative food products.This work was funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project Mobilizador Norte-01-0247-FEDER-024479: ValorNatural ®. This work was also supported by LA/P/0045/2020 (ALiCE), UIDB/50020/2020 and UIDP/50020/2020 (LSRE-LCM), and UIDB/ 00690/2020 (CIMO) funded by national funds through FCT/MCTES (PIDDAC). L. Barros and R. Calhelha also thank the national funding by FCT, P.I. through the institutional scientific employment and individual program-contract, and Júlia Cristiˆe Kessler acknowledges her Ph.D scholarship (ref. 2020.06656.BD) by FCT.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

β-Carotene colouring systems based on solid lipid particles produced by hot melt dispersion

In this work, β-carotene was selected to develop a novel study, namely a food colorant system based on beeswax solid lipid particles obtained by hot melt dispersion. The obtained microparticles were characterized by optical microscopy, scanning electron microscopy, particle size analysis and Fourier Transform Infrared spectroscopy. It was observed that the obtained size can be modulated by using different amounts of emulsifier, as well as the dispersing capability. In a final stage, the obtained particles were tested concerning their colorant power by selecting a food matrix widely appreciated and consumed (mayonnaise). Moreover, the formulation providing the best hue and dispersibility (formulation containing 3% of Tween 80, and β-carotene at 5 mg/25 g of commercial mayonnaise) was analysed along a storage period of 15 days concerning colour, nutritional value and chemical composition. The results pointed out for colour stability and nutritional value maintenance, after 15 days under storage at 6 °C.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UIDB/00690/2020), and to UIDB/50020/2020 of the Associate Laboratory LSRE-LCM - funded by national funds through FCT/MCTES (PIDDAC); national funding by FCT, PI, through the institutional scientific employment program-contract for L. Barros’s and I. Fernandes contract; to the project AllNat for the contract of C. Caleja (Project AllNat POCI-01-0145-FEDER-030463), the Valor Natural project for the contract of E. Pereira (Mobilized Project Norte-01-0247- FEDER-024479), and FCT for the PhD research grant SFRH/BD/147326/2019 (S.C. Rezende). This work is also funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project Mobilizador Norte-01- 0247-FEDER-024479: ValorNatural®; and to FEDER-Interreg España- Portugal programme for financial support through the project TRANSCoLAB 0612_TRANS_CO_LAB_2_P.info:eu-repo/semantics/publishedVersio

Obtaining aromatic extracts from portuguese Thymus mastichina L. by hydrodistillation and supercritical fluid extraction with CO2 as potential flavouring additives for food applications

Humans often respond to sensory impulses provided by aromas, and current trends have generated interest in natural sources of fragrances rather than the commonly used synthetic additives. For the first time, the resulting aroma of a selected culture of Thymus mastichina L. was studied as a potential food ingredient. In this context, dried (DR) and fresh (FR) samples were submitted to carbon dioxide (CO2) supercritical extraction (SFE) and hydrodistillation (HD) methods. The extracts were characterised according to their volatile composition by GC-MS, cytotoxicity against a non-tumour cell culture, and sensory attributes (odour threshold and olfactive descriptors). The most abundant aromas were quantified, and the analysis performed by GC-MS revealed an abundance of terpenoids such as thymol chemotype, followed by the precursors -terpinene and p-cymene. DR and FR extracts (EX) obtained from SFE-CO2 show the highest content of thymol, achieving 52.7% and 72.5% of the isolated volatile fraction. The DR essential oil (EO) contained the highest amount of terpenoids, but it was also the most cytotoxic extract. In contrast, SFE-CO2 products showed the lowest cytotoxic potential. Regarding FR-OE, it had the lowest extraction yield and composition in aroma volatiles. Additionally, all samples were described as having green, fresh and floral sensory notes, with no significant statistical differences regarding the odour detection threshold (ODT) values. Finally, FR-EX of T. mastichina obtained by SFE-CO2 presented the most promising results regarding food application.This research was funded by the European Regional Development Fund (ERDF) through the Regional Operational Program North 2020, within the scope of Project Mobilizador Norte- 01-0247-FEDER-024479: ValorNatural. This work was financially supported by: LSRELCM Base- UIDB/50020/2020 and Programmatic- UIDP/50020/2020 and CIMO UIDB/00690/2020, funded by national funds through FCT/MCTES (PIDDAC). L. Barros also thanks the national funding by FCT, P.I. through the institutional scientific employment and individual program contract, and Júlia Cristiê Kessler and Filipa Mandim acknowledges their Ph.D. scholarships by Fundação para a Ciência e a Tecnologia (FCT) (2020.06656.BD and SFRH/BD/146614/2019, respectively).info:eu-repo/semantics/publishedVersio