Browsing by Author "Ramos, Oscar L."
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- Cellulose from sugarcane bagasse as a potential prebiotic agentPublication . Freixo, Ricardo; Bastos, Francisca; Costa, Eduardo; Ribeiro, Alessandra B.; Pereira, Carla F.; Pintado, Manuela E.; Ramos, Oscar L.
- Design of green routes for cellulose extraction from a sugarcane by-productPublication . Casanova, Francisca; Pereira, Carla F.; Freixo, Ricardo; Ribeiro, Alessandra A.; Costa, Eduardo; Pintado, Manuela E.; Fernandes, João C.; Ramos, Oscar L.
- Design of β-lactoglobulin micro- and nanostructures by controlling gelation through physical variablesPublication . Simões, Lívia S.; Araújo, João F.; Vicente, António A.; Ramos, Oscar L.β-lactoglobulin (β-Lg) is the major protein fraction of bovine whey serum and its principal gelling agent. Its gelation capacity enables conformational changes associated with protein-protein interactions that allow the design of structures with different properties and morphologies. Thus, the aim of this work was to successfully use β-Lg, purified from a commercial whey protein isolate, to develop food-grade micro- (with diameters between 200 and 300 nm) and nano- (with diameters ≤ 100 nm) structures. For this purpose, the phenomena involved in β-Lg gelation were studied under combined effects of concentrations (from 5 to 15 mg mL−1), heating temperature (from 60 to 80 °C) and heating time (from 5 to 25 min) for pH values of 3, 4, 6 and 7. The effects of such conditions on β-Lg structures were evaluated and the protein was fully characterized in terms of size, polydispersity index (PDI) and surface charge (by dynamic light scattering – DLS), morphology (by transmission electron microscopy - TEM) and conformational structure (circular dichroism, intrinsic and extrinsic fluorescence). Results have shown that β-Lg nanostructures were formed at pH 3 (with diameters between 12.1 and 22.3 nm) and at 7 (with diameters between 8.9 and 35.3 nm). At pH 4 structures were obtained at macroscale (i.e., ≥ 6 μm) for all β-Lg concentrations when heated at 70 and 80 °C, independent of the time of heating. For pH 6, it was possible to obtain β-Lg structures either at micro- (245.0 – 266.4 nm) or nanoscale (≤ 100 nm) with the lowest polydispersity (PDI) values (≤ 0.25), in accordance with TEM analyses, for heating at 80 °C for 15 min. Intrinsic and extrinsic fluorescence data and far-UV circular dichroism spectra measurements revealed conformational changes on β-Lg structure that support these evidences. A strict control of the physical and environmental conditions is crucial for developing β-Lg structures with the desired characteristics, thus calling for the understanding of the mechanisms of protein aggregation and intermolecular interaction when designing β-Lg structures with novel functionalities.
- Elevating skincare science: grape seed extract encapsulation for dermatological carePublication . Castro, Maria Leonor; Azevedo-Silva, João; Valente, Diana; Machado, Adriana; Ribeiro, Tânia; Ferreira, João Paulo; Pintado, Manuela; Ramos, Oscar L.; Borges, Sandra; Baptista-Silva, SaraThe skin is the largest organ in the human body and serves multiple functions such as barrier protection and thermoregulation. The maintenance of its integrity and healthy structure is of paramount importance. Accordingly, technological advances in cosmetic sciences have been directed towards optimizing these factors. Plant-derived ingredients have been explored for their bioactivity profiles and sustainable sources. Grape by-products contain a group of bioactive molecules that display important biological activities. Nonetheless, many of these molecules (e.g., phenolic compounds) are unstable and susceptible to degradation. So, their encapsulation using nano/microsystems (i.e., microdispersions) has been explored as a promising solution. In this work, two grape seed extracts were obtained, one from a single grape variety (GSE-Ov) and another from a mix of five grape varieties (GSE-Sv). These extracts were analysed for their antioxidant and antimicrobial activities, as well as their chemical composition and molecular structure. The extract that showed the most promising properties was GSE-Ov with a DPPH IC50 of 0.079 mg mL−1. This extract was encapsulated in soy lecithin microdispersions coated with pectin, with an encapsulation efficiency of 88.8%. They showed an in vitro release of polyphenols of 59.4% during 24 h. The particles displayed a zeta potential of −20.3 mV and an average diameter of 13.6 µm. Microdispersions proved to be safe under 5 and 2.5 mg mL−1 in HaCaT and HDF cell models, respectively. Additionally, they demonstrated anti-inflammatory activity against IL-1α when tested at 2 mg mL−1. This work enabled the valorisation of a by-product from the wine industry by using natural extracts in skincare products.
- Grape by-products in sustainable cosmetics: nanoencapsulation and market trendsPublication . Castro, Maria Leonor; Ferreira, João Paulo; Pintado, Manuela; Ramos, Oscar L.; Borges, Sandra; Baptista-Silva, SaraThe largest human organ, the skin, serves a variety of essential functions including protection, preservation of water and electrolytes, regulation of body temperature, and fat storage. Its maintenance and preservation are supported by cosmetic products, whose functions include cleaning, protection, and modulation. The market for these products is predicted to increase from 100.13 billion USD in 2021 to 145.82 billion USD in 2028. Recently, it has been suggested that grape by-products (totalling 14.5 million tons per year just in Europe) has a great potential to be used in the creation of new cosmetic products. In this regard, this article aims to provide a comprehensive overview of the current state of knowledge regarding the bioactive compounds in grape pomace, the advantages of applying them to the skin, and the main cosmetic products already on the market incorporating these bioactives. Most of these compounds are derived from the Vitis vinifera L. species, and exhibit several biological properties, such as antioxidant, antimicrobial, anti-inflammatory, inhibition of skin degrading enzymes, protection from UVA damage, increased cell viability, and skin whitening effect. On the other hand, nanoencapsulation techniques can provide a significant improvement in the stability of grape-derived bioactive compounds, in particular of resveratrol, and this issue is also addressed in a critical manner in this review.
- Nanostructures of whey proteins for encapsulation of food ingredientsPublication . Ramos, Oscar L.; Pereira, Ricardo N.; Simões, Lívia S.; Madalena, Daniel A.; Rodrigues, Rui M.; Teixeira, José A.; Vicente, António A.The most current and high-level research is being taken on the use of nanoscience and nanotechnology due to its varied application in numerous fields of science. Food nanotechnology, and in particular, the development and application of bio-based nanostructures are an emerging area having a high potential to engender new products and processes in the food industry. This chapter intends to discuss whey protein-based nanostructured systems (i.e., whey protein isolate, whey protein concentrate, β-lactoglobulin, and α-lactalbumin) for encapsulation of food ingredients. These protein nanostructures have unique properties, such as a high nutritional value, GRAS nature, gelling capability, and can be easily prepared and controlled. They have also the ability to conjugate a large variety of food ingredients (e.g., antioxidants, vitamins, minerals, flavors, and odors) via amino groups or ionic and hydrophobic interactions. This behavior will prevent the degradation of sensitive bioactives, while permitting a site-specific action and controlled delivery rate due to the swelling behavior of the gel in reaction to external and physical stimuli such as temperature, enzymes, pH, or ionic strength), thus contributing to an improved bioavailability of such ingredients. The potential of whey protein nanostructures for encapsulation and controlled delivery of food ingredients will be addressed in a critical manner in this chapter. Moreover, various techniques used for their nanoencapsulation and evaluation of their stability during storage will also be discussed. The behavior and bioavailability of whey nanostructures and their associated/encapsulated food ingredients will be discussed using insights from in vitro and in vivo gastrointestinal systems together with potential cytotoxicity, cellular uptake, and allergenicity via in vitro cell lines. Finally, examples of such nanostructures applied in food matrices will be described, as well as the main challenges for their commercial use.
- Porphyridium cruentum: a factory for the production of a new polysaccharide-based biomaterial for tissue regenerationPublication . Duarte, Marta M.; Suprinovych, Artem; Silva, Inês V.; Ramos, Oscar L.; Costa, Joana R.; Rojo, Luis; Oliveira, Ana L.Marine algae and their metabolites have been widely recognized for their bioactive properties with applications in various industries, such as nutraceutical, cosmetical, and pharmaceutical. In this study, the best strategy for the extraction and processing of the exopolysaccharides (EPS) from Poryphydium cruentum for a laboratory scale was discussed, and the collected, purified EPS fraction was extensively characterized. The results show that impurities and other co-precipitants can be significantly reduced via trichloroacetic acid (TCA) treatment, followed by dialysis, resulting in a more purified EPS fraction with a higher carbohydrate content and solubility ability, at the cost of lower mass yield. The obtained EPS fraction was of a high molecular weight, presented a high crystallinity index, was thermally stable and cytocompatible within the range of tested concentrations. These results show its potential to be used as a new platform for healing and regeneration of chronic wounds.
- Sugarcane as a sustainable source of biologically active carboxymethyl cellulosePublication . Casanova, Francisca; F. Pereira, Carla; Freixo, Ricardo; Costa, Eduardo; Ribeiro, Alessandra A.; Pintado, Manuela E.; Fernandes, João C.; Ramos, Oscar L.
- Sugarcane bagasse cello-oligosaccharides as prebiotic agentsPublication . Freixo, Ricardo; Ribeiro, Alessandra; Bastos, Francisca; F. Pereira, Carla; Costa, Eduardo; Pintado, Manuela E.; Ramos, Oscar L.
- Suitability of β-lactoglobulin micro- and nanostructures for loading and release of bioactive compoundsPublication . Simões, Lívia S.; Abrunhosa, Luís; Vicente, António A.; Ramos, Oscar L.β-lactoglobulin (β-Lg) has the ability to form three-dimensional networks when heated above denaturation temperature (ca. 76 °C), since it undergoes conformational changes followed by subsequent protein-protein interactions, which allows designing stable micro- and nanostructures with affinity to bind to a wide range of molecules. In this sense, β-Lg micro (with particle size from 200 to 300 nm) and nano (with particle size ≤ 100 nm) structures were developed as a delivery system for the controlled release of hydrophilic and hydrophobic model compounds. Several concentrations of bioactive compounds were incorporated into β-Lg micro- and nanostructures and their association efficiency (AE) and loading capacity (LC) were determined. β-Lg structures were characterized in terms of structural properties, morphology, binding mechanisms, conformational changes and secondary structure. The impact of several conditions (e.g., pH, thermal processing, ionic strength and storage temperature) on the stability of β-Lg structures was also investigated. The release profile of bioactive compounds from β-Lg structures was determined in vitro using two food simulants with different hydrophobicities under different temperature conditions (at 4 °C and 25 °C). Data recorded showed that β-Lg nanostructures had the highest AE and LC comparing with β-Lg microstructures, for both bioactive compounds tested. β-Lg micro- and nanostructures with or without association of bioactive compounds showed to be stable under acidic (pH 2 to 3), neutral (pH 6) or alkaline (pH 10) conditions, thermal treatments up to 70 °C and during storage for 50 and 90 days at 25 °C and 4 °C, maintaining their particle size, PDI and surface charge (p > 0.05). The release kinetics of bioactive compounds from micro- and nanostructures fitted well the Linear Superimposition Model, being the relaxation the main release mechanism. Both compounds showed an initial burst effect followed by a slow release. All these findings provide new insights on which conditions the β-Lg micro- and nanostructures are more stable, and therefore more suitable to act as potential delivery systems for hydrophilic and hydrophobic bioactive compounds.