High-pressure homogenization for the recovery of value-added compounds from vegetable matrices

High-pressure homogenization (HPH) has been recently reported to be an effective mechanical cell disruption technology to unlock the intracellular compounds, tightly entrapped in vegetable tissues, using only water as an extraction medium. In this work, HPH was used to promote the recovery of the bioactive compounds contained in white and black sesame seeds (Sesamum indicum). Aqueous suspensions (10% w/w) of the seeds, obtained by high-shear mixing (HSM) for 5 min at 20000 rpm, were treated by HPH at 100 MPa or 140 MPa for up to 10 passes and different temperatures (25 and 50 °C). The HPH treatment caused a considerable cell deagglomeration and fragmentation effect, as shown by the decrease in the size distribution of the suspended particles. At the same time, the HPH treatment also significantly increased, more than twofold, the polyphenolic content and antioxidant activity of the aqueous extracts, in comparison to HSH. Remarkably, a significant decrease (-20%) in antioxidant activity was observed during HPH processing at a higher temperature, likely due to the degradation of thermolabile compounds. Higher operating pressures increased the antioxidant activity of the aqueous extracts but caused also the increased release of polyphenol oxidases, which induced a higher degradation of the antioxidant activity of the extracts over time in comparison with samples processed at lower pressure. However, spray drying of the HPH-treated suspensions, without any further treatment or additive, resulted in the efficient stabilization of the extracts

Changing the vision in smart food design utilizing the next generation of nanometric delivery systems for bioactive compounds

In modern foods, the delivery systems for bioactive compounds play a fundamental role in health promotion, wellbeing, and disease prevention through diet. Nanotechnology has secured a fundamental role in the fabrication of delivery systems with the capability of modulating the in-product and in-body behavior for augmenting bioavailability and activity of bioactive compounds. Structured nanoemulsions and nanoparticles, liposomes, and niosomes can be designed to improve bioactives preservation after ingestion, mucoadhesion, as well as of their release and pathophysiological relevance. In the future, it is expected that the delivery systems will also contribute to augment the effcacy of the bioactive compounds, for example by improving the intestinal absorption and delivery in the bloodstream, as well as promoting the formation of additional bioactive metabolites by regulating the transformations taking place during digestion and the interaction with the intestinal microbiota

Distribution of gas pressure inside a hopper discharging fine powders

In this paper the mechanism of discharge of fine powders from hoppers is examined. Gas pressure measurements were taken in the proximity of the hopper outlet, mainly along the axis, while discharging fine powders. Different types of pressure traces were detected depending on the solid properties. A simple model was developed to account for the main features of pressure profiles. The main hypothesis relies on the presence of a surface near the hopper outlet which defines a discontinuous change in the voidage of the discharging solids. From the fluid dynamic point of view, the solid above this surface bl:haves as a permeable compact; the solid below, instead, can be considered as a moving suspension of solids in gas. This region appears to be the major responsible of the pressure gradients inside the hopper. A good agreement between model and results indicates that, in spite of its simplicity, the models accounts for the main phenomena involved. (C) 1997 Elsevier Science Ltd