In this study, the trend of VOCs of dietary fiber samples, coming from three different watermelon cultivars Citrullus lanatus L. (variety Gavina®®, Crimson sweet, and Asahi myiako) was investigated. This foodstuff, obtained as a by-product of residual agri-food production, has gained increasing attention because of its many bioactive components and high dietary fiber content. The result is a fibrous material for specific applications in food manufacturing, such as corrector for some functional and technological properties. In this study, a method based on headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) was used to characterize the aromatic profiles of the dried raw materials. Therefore, the VOCs of the samples of the three cultivars were investigated. Experimental results have shown that watermelon fibers generate VOCs, which can be grouped into six common classes of analytes. The different distributions of the identified compounds made it possible to effectively differentiate the three cultivars studied based on their peculiar aroma profiles. In particular, Gavina®® fiber is distinguished by the high content of terpenes, Asahi myiako by the presence of aldehydes generated as fatty acid metabolites, and Crimson sweet by the higher content of acetyl esters.
Due to the increasing demand for Rare Earth Elements (REE) and the current political scenario, it is essential to recover these elements from industrial or mining waste. Zeolites are microporous materials little investigated for REEs recycle. Here, we propose the use of NH 4 + -exchanged synthetic zeolite L for cerium recovery from a solution mimicking the Ce 3+ concentration of the liquors deriving from the recovery of spent catalysts (0.002 M). A NH 4 + -exchanged sample was used since the presence of only ammonium as exchangeable cation in the zeolite porosities greatly simpli es the Ce recovery once the exchange is accomplished. The aim of this work is twofold, in fact we want to investigate the exploitability of zeolite L as cation exchanger in the Ce recovery and determine the best working conditions. The investigated process consists of a coupled cation exchange: 1) Ce 3+ (solution)+3NH 4 + + (zeolite) ↔ Ce 3+ (zeolite)+3NH 4 + +(solution). In the rst exchange the NH 4 + cations -present in the zeolite porosities-are exchanged with the Ce 3+ of the solution and in the second experiment the Ce 3+ trapped into the zeolite is recovered through a further exchange with the NH 4 + of a rich solution. The best working conditions for Ce 3+ exchange of NH 4 -L are: batch system, liquid/solid ratio equal to 90 mL/g and 180 mL/g, 24 h of contact at 25 °C. The resulting cerium adsorption capacity (q t ) is equal to ~25 mg/g and ~39 mg/g and the removal e ciency 100 % and 77 % for the two tested liquid/solid ratios, respectively. The kinetics was proved to be fast and consistent with industrial timing, no energy cost for temperature setting is required and the acid pH (~4) of the solutions does not affect the zeolite structure stability and its exchange performance. At these conditions, cerium of the solution was rst incorporated into the zeolite porosities and then completely recovered. It has been demonstrated that the zeolite framework is not affected by the exchange so that the same absorbent can be employed many times.
In this study, the trend of Volatile Organic Compounds (VOCs) in dietary fiber samples from the winter melon (Cucumis Melo var. Inodorus, Yellow Canary type) were investigated. This foodstuff, obtained as a by-product of agri-food production, has gained increasing attention and is characterized by many bioactive components and a high dietary-fiber content. As regards fiber, it is poorly colored, but it may be whitened by applying a bleaching treatment with H2O2. The result is a fibrous material for specific applications in food manufacturing, for example, as a corrector for some functional and technological properties. This treatment is healthy and safe for consumers and widely applied in industrial food processes. In this study, a method based on headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC-MS) was applied for the characterization of the aromatic profile of the dried raw materials. Furthermore, VOC variation was investigated as function of the bleaching treatment with H2O2. The bleached samples were also analyzed after a long storage period (24 months), to assess their stability over time. As a result, the VOC fraction of the fresh raw fiber showed nine classes of analytes; these were restricted to seven for the bleached fiber at t0 time, and further reduced to four classes at the age of 24 months. Alcohols were the main group detected in the fresh raw sample (33.8 % of the total chromatogram area), with 2,3-butanediol isomers as the main compounds. These analytes decreased with time. An opposite trend was observed for the acids (9.7% at t0), which increased with time and became the most important class in the 24-month aged and bleached sample (57.3%).
Developing simple and effective chemistry able to convert industrial waste streams into valuable chemicals is a primary contributor to sustainable development. Working in the context of biodiesel production, we found that plain bisulfate on silica (SSANa, 3.0 mmol/g) proved to be an optimal catalyst to convert glycerol into solketal. With the assistance of a proper anhydrification technique, isolated yields of 96% were achieved working in mild conditions, on 100 g scale.
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