Waste orange peel represents a heavy burden for the orange juice industry, estimated in several million tons per year worldwide; nevertheless, this by-product is endowed with valuable bioactive compounds, such as pectin, polyphenols, and terpenes. The potential value of the waste orange peel has stimulated the search for extraction processes, alternative or complementary to landfilling or to the integral energy conversion. This study introduces controlled hydrodynamic cavitation as a new route to the integral valorization of this by-product, based on simple equipment, speed, effectiveness and efficiency, scalability, and compliance with green extraction principles. Waste orange peel, in batches of several kg, was processed in more than 100 L of water, without any other raw materials, in a device comprising a Venturi-shaped cavitation reactor. The extractions of pectin (with a remarkably low degree of esterification), polyphenols (flavanones and hydroxycinnamic acid derivatives), and terpenes (mainly d-limonene) were effective and efficient (high yields within a few min of process time). The biomethane generation potential of the process residues was determined. The achieved results proved the viability of the proposed route to the integral valorization of waste orange peel, though wide margins exist for further improvements.

Chemical extraction, water retting, microbiological and enzymatic methods were applied on entire nettle stalks and/or unretted decorticated fiber of a selected fiber nettle clone. Morphological and mechanical properties and chemical composition were then determined on fiber samples. The first interesting result concerned the good degree of separation between fibers and shives obtained by mechanical scutching applied on stalks stored for 1 year, probably resulting from natural retting processes occurring during the storage. Microbiological retting (anaerobic plus aerobic bacteria) of entire stalks and/or unretted decorticated fiber produced fibers with a higher quality than water retting. Both enzymes used (Viscozyme ^® L and Pectinex^® Ultra SP-L), improved fiber quality if EDTA was added. The enzyme vat retting gave good results on both water-retted fibers and unretted decorticated fibers, while the spray enzyme treated fibers usually displayed thicker diameter, lower cellulose content and, for Viscozyme ^® L, lower strength values, without differences between the two storage methods used after enzyme application.

The prolonged lockdown imposed to contain the COrona VIrus Disease 19 COVID-19 pandemic prevented many people from direct contact with nature and greenspaces, raising alarms for a possible worsening of mental health. This study investigated the effectiveness of a simple and affordable remedy for improving psychological well-being, based on audio-visual stimuli brought by a short computer video showing forest environments, with an urban video as a control. Randomly selected participants were assigned the forest or urban video, to look at and listen to early in the morning, and questionnaires to fill out. In particular, the State-Trait Anxiety Inventory (STAI) Form Y collected in baseline condition and at the end of the study and the Part II of the Sheehan Patient Rated Anxiety Scale (SPRAS) collected every day immediately before and after watching the video. The virtual exposure to forest environments showed effective to reduce perceived anxiety levels in people forced by lockdown in limited spaces and environmental deprivation. Although significant, the effects were observed only in the short term, highlighting the limitation of the virtual experiences. The reported effects might also represent a benchmark to disentangle the determinants of health effects due to real forest experiences, for example, the inhalation of biogenic volatile organic compounds (BVOC).