ABSTRACT
An innovative method combining frontal filtration with ultraviolet (UV) curing has been implemented to design cellulosic nanocomposite films with controlled anisotropic textures from nanometric to micrometric length scales. Namely, an aqueous suspension containing poly (ethylene glycol) diacrylate polymer (PEGDA) as a photocurable polymer and cellulose nanocrystals (CNCs) at a 70/30 mass ratio was processed by frontal filtration, followed by in-situ UV-curing in a dedicated cell. This procedure allowed designing nanocomposite films with highly oriented and densely-packed CNCs, homogeneously distributed in a PEGDA matrix over a thickness of ca. 500 µm. The nanocomposite films were investigated with small-angle X-ray scattering (SAXS), by raster-scanning along their height with a 25 µm vertically-collimated X-ray beam. The CNCs exhibited a high degree of orientation, with their director aligned parallel to the membrane surface, combined with an increase in the degree of alignment as concentration increased towards the membrane surface. Scanning electron microscopy images of fractured films showed the presence of regularly spaced bands lying perpendicular to the applied transmembrane pressure, highlighting the presence of a chiral nematic (cholesteric) organization of the CNCs with a pitch gradient that increased from the membrane surface to the bulk.
ABSTRACT
Chocolate is a complex soft material characterized by solid particles (cocoa powder, milk solid particles and sugar crystals) dispersed in a crystallized fat matrix mostly composed of cocoa butter (CB). Important chocolate properties such as snap, and visual appearance are strongly dependent on the internal molecular arrangement (polymorph), size and shape, as well as the spatial distribution of CB crystals within the chocolate mix. In recent years confectionary companies have put increasing effort in developing novel chocolate recipes to improve the nutritional profile of chocolate products (e.g., by reducing the amount of high saturated fat and sugar content) and to counteract the increasing price of cocoa butter as well as sustainability issues related to some chocolate ingredients. Different reformulation strategies can dramatically affect the crystallization thermodynamic and kinetic behaviour of cocoa butter; therefore, affecting the structural and sensorial properties of chocolate. In this review we analyse how different reformulation strategies affect the crystallization behaviour of cocoa butter and, hence, the structural and sensorial properties of chocolate. In particular, this work discusses the effect of: (1) CB replacement with emulsions, hydrogels, oleogels and oleofoams; (2) CB dilution with limonene or cocoa butter equivalents; (3) replacement or reduction of the amount of sugar and milk in chocolate. We found that there is certainly potential for successful novel alternative chocolate products with controlled crystalline properties; however, further research is still needed to ensure sensory acceptance and reasonable shelf-life of these novel products.
