Green Extraction Processes for Complex Samples from Vegetable Matrices Coupled with On-Line Detection System: A Critical Review.

The detection of analytes in complex organic matrices requires a series of analytical steps to obtain a reliable analysis. Sample preparation can be the most time-consuming, prolonged, and error-prone step, reducing the reliability of the investigation. This review aims to discuss the advantages and limitations of extracting bioactive compounds, sample preparation techniques, automation, and coupling with on-line detection. This review also evaluates all publications on this topic through a longitudinal bibliometric analysis, applying statistical and mathematical methods to analyze the trends, perspectives, and hot topics of this research area. Furthermore, state-of-the-art green extraction techniques for complex samples from vegetable matrices coupled with analysis systems are presented. Among the extraction techniques for liquid samples, solid-phase extraction was the most common for combined systems in the scientific literature. In contrast, for on-line extraction systems applied for solid samples, supercritical fluid extraction, ultrasound-assisted extraction, microwave-assisted extraction, and pressurized liquid extraction were the most frequent green extraction techniques.

Pressurized liquid extraction coupled in-line with SPE and on-line with HPLC (PLE-SPExHPLC) for the recovery and purification of anthocyanins from SC-CO2 semi-defatted Açaí (Euterpe oleracea).

This study aimed to extract anthocyanins from dried and semi-defatted açaí pulp using green technologies based on the coupling of pressurized liquid extraction (PLE) with in-line purification through solid-phase extraction (SPE) and on-line analysis by high-performance liquid chromatography (HPLC). Critical parameters that affect the extraction efficiency and purification were investigated and optimized by response surface methodology (RSM). PLE was performed with acidified water at different pH (2.0, 4.5, and 7.0) and temperatures (40, 80, and 120 °C) at 15 MPa, 2 mL/min, and solvent-to-feed mass ratio equal to 40. SPE was optimized in a column packed with the adsorbent PoraPak™ Rxn. Different ethanol concentrations (50, 75, and 100 %) and temperatures (30, 40, and 50 °C) were evaluated for the anthocyanin's elution. The optimal conditions of the two experimental designs were determined by the RSM, firstly for PLE: 71 °C and pH 2; then using this PLE condition, the optimization of the SPE was obtained: 30 °C and 50 % ethanol. The developed PLE method provided similar anthocyanin yield to other techniques, and the coupling with SPE in-line produced an extract 5-fold more concentrated than PLE alone. Therefore, the system (PLE-SPE × HPLC-PDA) proved to be a powerful tool for monitoring the extraction process in real-time.

A spatially explicit assessment of sugarcane vinasse as a sustainable by-product.

This study evaluates the benefits of mineral fertilizers replacement for biodigested vinasse. Data from experimental anaerobic digestion (AD) of vinasse were applied to support the analysis. Based on previous experiments, this assessment assumed that vinasse production could reach 2.38 × 107 m3/year generating around 66,585 MWh/year of electric energy from biogas burning in the Administrative Region of Campinas (ARC). This amount of energy could supply more than 103,000 inhabitants and avoid 35,892 tCO2eq/year (from electric energy replacement). The biodigested vinasse might also reduce the total N, P, and K mineral fertilizers demand per hectare of sugarcane crop in 30%, 1%, and 46%, respectively, avoiding additional greenhouse gas emissions of 111,877 tCO2eq/year. There is no biodigested vinasse surplus for a moderate fertigation rate of 100 m3/ha, complying with local environmental laws related to nutrients excess side effects in areas destined to sugarcane crop. Notwithstanding, a Geographic Information System analysis for a small adjacent area to ARC indicated nine different fertigation rates, ranging from 50 to 100 m3/ha. Even though the general analysis for ARC shows high NPK replacement levels, the fertigation practices should be subsidized for robust soil analysis and adequate to safe environmental levels. A management tool can be designed using the results here presented to subsidize investments for AD widespread adoption by the sugarcane industry to catch a reasonable practice from the economic and environmental perspectives.

Sustainability assessment of water hyacinth fast pyrolysis in the Upper Paraguay River basin, Brazil.

Fast pyrolysis of naturally produced water hyacinth was assessed through Emergy accounting approach. Two analyses were carried out to evaluate the influence of additional services and externalities on Emergy indicators for a pyrolysis plant unit able to process 1000 kg of dry biomass per hour. The initial approach was a traditional Emergy assessment in which financial fluxes and externalities were not considered. The second approach included taxes and fees of the Brazilian government, interests related to financing operations and assumes a reserve financial fund of 5% of the total investment as externalities cost. For the first evaluation, the renewability of 86% indicates that local and renewable resources mainly support the process and the Emergy Yield Ratio of 3.2 shows that the system has a potential contribution to the regional economy due to the local resources use. The inclusion of financial fluxes and externalities in the second evaluation reduces both renewability and Emergy Yield Ratio, whereas it increases the Emergy Investment Ratio which means a higher dependence on external resources. The second analysis allows portraying significant forces of the industrial and financial systems and the evaluation of the externalities' impact on the general system Emergy behavior. A comparison of the renewability of water hyacinth fast pyrolysis with other biofuels like soybean biodiesel and sugarcane ethanol indicates that the former is less dependent on fossil fuel resources, machinery and fertilizers. To complement the sustainability assessment provided by the Emergy method, a regular financial analysis for the second defined system was done. It shows that the system is financially attractive even with the accounting of additional costs. The results obtained in this study could be used as the maximum and minimum thresholds to subsidize regulatory policies for new economic activities in tropical wetlands involving natural resources exploitation and bio-industrial systems.