Sustainability, Innovation, and Green Chemistry in the Production and Valorization of Phenolic Extracts from Olea europaea L.

This paper describes a circular economy process based on environmentally and economically sustainable procedures which was applied to the sector of olive oil processing on an industrial scale. Olea europaea L. tissues and by-products represent a renewable and low-cost source of polyphenols, in particular hydroxytyrosol (HTyr), a naturally occurring compound well known for its biological properties. Specifically, green leaves (GL), dried leaves (DL), and pitted olive pulp were treated with water in a pneumatic extractor to obtain the corresponding polyphenolic extracts. Three standardized fractions, named Soft Extract Olea GL, Soft Extract Olea DL, and Soft Extract Olea HTyr resulted after the following two steps: a separation process carried out by membrane technology, and a concentration step performed under reduced pressure and low temperature. The polyphenolic fractions showed antiradical activity and have potential industrial applications in the food, nutraceutical, pharmaceutical, feed, and agronomic fields. Novel functionalized extracts containing hydroxytyrosol methyl carbonate (HTyr-MC) were obtained from Soft Extract Olea HTyr through an innovative approach based on green chemistry procedures, which appear to be a promising tool to increase the applications of the polyphenolic extracts

Structural colour from helicoidal cell-wall architecture in fruits of Margaritaria nobilis

The bright and intense blue-green coloration of the fruits of Margaritaria nobilis (Phyllanthaceae) was investigated using polarization-resolved spectroscopy and transmission electron microscopy. Optical measurements of freshly collected fruits revealed a strong circularly polarized reflection of the fruit that originates from a cellulose helicoidal cell wall structure in the pericarp cells. Hyperspectral microscopy was used to capture the iridescent effect at the single-cell level.This work was supported by the Leverhulme Trust (F/09- 741/G) and a BBSRC David Phillips fellowship (BB/K014617/1). P.V. acknowledges support from the US Air Force Office of Scientific Research under award number FA9550-10-1-0020. U.S. acknowledges support from the Adolphe Merkle foundation and the Swiss National Science Foundation through the National Centre of Competence in Research Bio-Inspired Materials

Ultrafast nonlinear response of gold gyroid three-dimensional metamaterials

We explore the nonlinear optical response of 3D gyroidal metamaterials, which show >10-fold enhancements compared to all other metallic nanomaterials as well as bulk gold. A simple analytical model for this metamaterial response shows how the reflectivity spectrum scales with the metal fill fraction and the refractive index of the material that the metallic nanostructure is embedded in. The ultrafast response arising from the interconnected 3D nanostructure can be separated into electronic and lattice contributions with strong spectral dependences on the dielectric filling of the gyroids, which invert the sign of the nonlinear transient reflectivity changes. These metamaterials thus provide a wide variety of tuneable nonlinear optical properties, which can be utilised for frequency mixing, optical switching, phase modulators, novel emitters, and enhanced sensing.This is the author's accepted manuscript. The final version is available from APS in Physical Review Applied at http://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.2.044002#fulltext#fulltext

A heterogeneous microbial consortium producing short-chain fatty acids from lignocellulose.

Microbial consortia are a promising alternative to monocultures of genetically modified microorganisms for complex biotransformations. We developed a versatile consortium-based strategy for the direct conversion of lignocellulose to short-chain fatty acids, which included the funneling of the lignocellulosic carbohydrates to lactate as a central intermediate in engineered food chains. A spatial niche enabled in situ cellulolytic enzyme production by an aerobic fungus next to facultative anaerobic lactic acid bacteria and the product-forming anaerobes. Clostridium tyrobutyricum, Veillonella criceti, or Megasphaera elsdenii were integrated into the lactate platform to produce 196 kilograms of butyric acid per metric ton of beechwood. The lactate platform demonstrates the benefits of mixed cultures, such as their modularity and their ability to convert complex substrates into valuable biochemicals

Invited Article: Chiral optics of helicoidal cellulose nanocrystal films

Cellulose nanocrystals (CNCs) in water suspensions behave as lyotropic liquid crystals forming a chiral nematic phase above a critical concentration. Such organization can be retained in solid films and give rise to an intense colored appearance. Here, we fully characterize their optical response by applying optical and scanning electron microscopy, imaging scatterometry and angle-resolved reflectance measurements. We show that the experimental results are well explained by computational modeling using the finite-difference time-domain method, but slightly less well by Berremann’s analytical model.This work was supported by the EPSRC Cambridge NanoDTC [No. EP/G037221/1 to R.M.], the National Centre of Competence in Research “Bio-InspiredMaterials”, the Ambizione program of the Swiss National Science Foundation [No. 168223 to B.D.W.], the European Research Council [No. ERC-2014-STG H2020 639088 to S.V. and A.G.D.], and the BBSRC David Phillips fellowship [No. BB/K014617/1 to S.V.]

HPLC/DAD, GC/MS and GC/GC/TOF analysis of Lemon balm (Melissa officinalis L.) sample as standarlized raw material for food and nutraceutical uses

Melissa officinalis L., commonly known as lemon balm, is a perennial herb belonging to Lamiaceae family. Traditionally administered in infusion form, it has therapeutic properties, such as sedative, carminative and antispasmodic, but also it is used for treatment of headache, rheumatism, indigestion and hypersensitivities. Lemon balm has a complex chemical composition. The aim of this work was the comprehensive characterization of secondary metabolites of a dried Lemon balm (Melissa officinalis L.) sample, through HPLC/DAD, GC/MS and GC/GC/TOF analysis, as raw material for the standardized phyto-complexes production useful for food and nutraceutical application. This sample contained rosmarinic acid (caffeic acid dimer) as the main compound of phenolic fraction (32.4 mg g-1). Citronellal was the most abundant compound in the volatile fraction, followed by α-citral and β-caryophyllene. The total citral amount, in terms of sum of α- and β-citral, was 149.4 mgcitral kg-1. Comprehensive two-dimensional GC fingerprint analysis of lemon balm produced rationalized peak patterns for up to 200 volatile compounds

Retrieving the Coassembly Pathway of Composite Cellulose Nanocrystal Photonic Films from their Angular Optical Response.

Aqueous suspensions of cellulose nanocrystals (CNCs) are known to self-assemble into a chiral nematic liquid crystalline phase, leading to solid-state nanostructured colored films upon solvent evaporation, even in the presence of templating agents. The angular optical response of these structures, and therefore their visual appearance, are completely determined by the spatial arrangement of the CNCs when the drying suspension undergoes a transition from a flowing and liquid crystalline state to a kinetically arrested state. Here, it is demonstrated how the angular response of the final film allows for retrieval of key physical properties and the chemical composition of the suspension at the onset of the kinetic arrest, thus capturing a snapshot of the past. To illustrate this methodology, a dynamically evolving sol-gel coassembly process is investigated by adding various amounts of organosilica precursor, namely, 1,2-bis(trimethoxysilyl)ethane. The influence of organosilica condensation on the kinetic arrest can be tracked and thus explains the angular response of the resulting films. The a posteriori and in situ approach is general; it can be applied to a variety of additives in CNC-based films and it allows access to key rheological information of the suspension without using any dedicated rheological technique.M.J.M. thanks NSERC for a Discovery Gran