Oihana Gordobil

Roasted hazelnut skins (RHSs), generated as by-products of industrial hazelnut processing, were extracted by pressurized liquid extraction to yield a hydroalcoholic extract (RHS-H). The extract was rich in polyphenols (308.4 ± 4.6 mg GAE/g) and proanthocyanidins (169.3 ± 10 mg CE/g) and showed strong antioxidant activity (DPPH EC₅₀ = 5.08 ± 1.08 µg/mL; TEAC = 2.82 ± 0.03 mM Trolox/mg) together with antimicrobial effects against Staphylococcus aureus and Staphylococcus epidermidis. RHS-H also enhanced the UV absorbance of synthetic UV filters. When incorporated into oil-in-water (O/W) cosmetic emulsions at low concentrations (0.2–2% w/w), RHS-H did not affect physicochemical stability: formulations maintained acceptable organoleptic properties, dermocompatible pH (4.7–5.5), electrostatic stability (ζ-potential ranging from –57 to –60 mV), and rheological behavior. Functionally, RHS-H increased the antioxidant activity of emulsions (radical scavenging > 80% vs. 52% in the blank), ensured microbial protection in challenge tests, and enhanced SPF by 9.4% at 0.2% w/w, with further improvements at higher concentrations, reaching broad-spectrum photoprotection (critical wavelength > 370 nm). Overall, RHS-H represents a natural multifunctional ingredient with antioxidant, preservative, and photoprotective properties, providing a sustainable strategy to upcycle hazelnut processing waste and reduce reliance on synthetic additives in cosmetic formulations.

Lignin nanoparticles (LNPs) are gaining increasing interest for applications in various fields, where the particle homogeneity, morphology, and surface properties are critical for performance. In this study, lignin obtained via kraft process from spruce and eucalyptus was employed as precursor for the fabrication of lignin nanoparticles with tunable physicochemical properties. Linear ester groups with varying chain lengths were introduced to systematically investigate the effects of the hydrophobic moiety distribution on lignin nanoparticle formation via solvent-shifting self-assembly. Results demonstrated that esterification-induced structural changes altered the balance of key noncovalent interactions (hydrogen bonding, π-π stacking, and hydrophobic interactions), which collectively governed the self-assembly process, with longer ester chains promoting compact particles with hydrophobic surfaces. By directly linking molecular-level modification of lignin to alterations in the inter- and intramolecular interactions driving the self-assembly of nanoparticles, this study provides a mechanistic framework for the rational design of lignin nanoparticles through controlled chemical modification, thereby expanding their application flexibility.

The goal of this study is to comprehensively evaluate the natural weathering performance of three wood species representing hardwood and softwood modified with the acetylation process. Alder (Alnus glutinosa L.), beech (Fagus sylvatica L.), and radiata pine (Pinus radiata D. Don) were characterised by various techniques to determine the aesthetical, chemical, and physical changes. The overall aesthetic performance of the investigated species was similar, with all showing a change in appearance after 9 months of exposure. However, the multi-sensor approach used for characterisation revealed differences in weathering behaviour related to surface erosion, wettability, and changes in chemical composition between the investigated species. An increase in the surface roughness observed for both hardwoods was associated with the erosion of the wood surface and the leaching of photodegraded chemical components. On the contrary, values of Sa remained relatively constant for acetylated radiata pine. Acetylated pine wood exhibited lower susceptibility to bleaching at the initial stage of the weathering process (3 months) and represented a more constant CIE L* compared to the investigated hardwood species. The contact angle measured with water gradually decreased in the case of acetylated radiata pine for up to six months, then it plateaued with a slight oscillation around 15°. For both hardwood species, the big drop was observed already after three months, followed by rather similar values. The PCA of IR spectra highlighted different mechanisms in the weathering of acetylated softwood and hardwood. The acetylated hardwood samples showed higher thermal stability than acetylated radiata pine. Experimental findings provide a comprehensive understanding of the long-term performance of acetylated wood, which directly influences its practical applications by enhancing design strategies, maintenance planning, product development, market acceptance, and overall sustainability. Performed tests have demonstrated the potential of underutilised hardwood species, enhanced through the acetylation process, to serve as alternative cladding materials to commonly used acetylated radiata pine.

Recent advancements in wood modification aim to enhance the inherent qualities of this versatile biological material, which includes renewability, ease of processing, and thermal insulation. This study focuses on evaluating the effectiveness of lignin as a protective agent for less durable wood species, namely, Pinus nigra and Fagus sylvatica L. The impregnation of wood with three various forms of lignin, such as kraft lignin, acetylated kraft lignin, and lignin nanoparticles, was carried out using the vacuum technique at room conditions. The results showed that the treatments significantly improve the hydrophobicity of wood surfaces, particularly in pine wood, and provide protection against UV ageing. Additionally, the treatments contributed to the stabilisation of moisture content at different humidity levels. Although slight colour variations were observed, their impact on the visual appearance was minimal, and the thermal analysis confirmed enhanced thermal properties. Additionally, plasma treatment further enhanced hydrophobicity after treatments, offering potential benefits in terms of moisture resistance and durability. The findings of this study highlight the promising effects of lignin-based treatments on wood properties, providing sustainable solutions for wood protection in various sectors. However, further optimisation is needed to fully explore the potential of lignin and lignin nanoparticles.

Heterogeneity of kraft lignin is one of the main limitations for the development of high-performance applications. Therefore, refining lignin using organic solvents is a promising strategy to obtain homogenous fractions with controlled quality in terms of structure and properties. In this work, one-step refining processes for hardwood kraft lignin using nine organic solvents of different chemical nature and polarity were carried out with the aim of investigating and understanding the effect of the type of organic solvent on the quality of resulting fractions. Structural features of both soluble and insoluble lignin fractions were assessed by GPC, Py-GC-MS, and FTIR linked to PCA analysis. Moreover, functional properties such as physical appearance, hygroscopicity, antioxidant capacity, and thermal properties were evaluated. The results evidenced the relationship between the nature and polarity of the solvents and the properties of the obtained soluble and insoluble fractions.

Daily consumption of synthetic sunscreens is harmful to the environment and consumers’ health, so greener alternatives need to be produced. Lignin is a multifunctional and widely available biopolymer that can replace several ingredients, but its dark color and low sun protection limit its perceived usefulness. With a survey made for this study, we explored the knowledge and attitudes of 230 consumers towards lignin-based sunscreen, their motives and barriers to purchase it, and how it relates to their environmental and health consciousness. Participants were also asked about their sunscreen habits, their familiarity with the environmental and health impacts of skincare, their perceptions of bio-based ingredients in general, and their skincare product purchasing decisions. Those who are more familiar with environmental issues have a positive attitude towards bio-based ingredients, are accustomed to purchasing more environmentally friendly skincare, and are likelier to be interested in a lignin product. Consumers are welcoming towards a natural, healthy, and environmentally friendly sunscreen alternative but are worried about the lower SPF. Because organic is perceived as luxurious, they are concerned about its price, and some are apprehensive about its pigmentation. While a lignin-based sunscreen at this stage of development is unlikely to take on the role of primary sunscreen on warm, sunny days, it may be more useful as a general-purpose, everyday product that can offer some protection, moisture, and coverage.