Pressurized liquid extraction assisted by high-intensity ultrasound to obtain hesperidin from lime waste: Integration of in-line purification and on-line chromatographic analysis.

Hesperidin is a phenolic compound usually found in citrus fruits, which is known for its anti-inflammatory and antioxidant properties. This bioactive compound has already been used to formulate medications to treat chronic venous insufficiency. In this work, through a system which allows the in-line coupling of the pressurized liquid extraction (PLE) and high-intensity ultrasound (HIUS) with solid phase extraction (SPE), and analysis by high-performance liquid chromatography with UV-Vis detector (HPLC-UV) in on-line mode, a method was developed to obtain, separate, and quantify hesperidin from the industrial waste of lime. An eco-friendly approach with water and ethanol as extraction solvents was used. Parameters such as temperature (80, 100, and 120 °C) and HIUS power (0, 200, and 400 W) were evaluated regarding hesperidin yield. In this context, the higher hesperidin yield (18.25 ± 1.52 mg/g) was achieved using water at a subcritical state (120 °C and 15 MPa). The adsorbent SepraTM C-18-E isolated hesperidin from the other extracted compounds employing 50% ethanol in the SPE elution. The possibility ofon-lineanalysis coupling a high-performance liquid chromatograph to an ultraviolet detector (HPLC-UV) system was studied and shown to be a feasible approach for developing integrated technologies. Conventional extractions and their antioxidant capacities were evaluated, highlighting the advantages of the HIUS-PLE-SPE extractive method. Furthermore, the on-linechromatographic analysis showed the potential of the HIUS-PLE-SPE- HPLC-UV system to quantify the extracted compounds in real time.

New selective and sustainable ultrasound-assisted extraction procedure to recover carnosic and rosmarinic acids from Rosmarinus officinalis by sequential use of bio-based solvents.

Carnosic (CA) and rosmarinic (RA) acids are the primary phenolic acids in hydrophilic rosemary extracts. Their combination exhibits high antioxidant activity and can be explored in several applications. This study aimed to develop an extraction procedure using bio-based solvents to recover two rosemary extracts, one rich in CA and the other in RA. By using ultrasound-assisted extraction (UAE) and a pool of 34 solvents, we evaluated nominal power (W), extraction time (min), and solvent water percentage (% H2O) regarding yield and selectivity. The authors propose a sequential UAE procedure validated by applying ethanol 99.5 % (v/v), 240 W, and 5 min to recover a rich fraction of 24.0 mgCA.gbiomass-1; followed by a second step using AmAc:LA (1:2 M ratio), 20 % H2O (m/m), 320 W, and 5 min that resulted in 8.4 mgRA.gbiomass-1. Our results indicate that modulating the solvent composition and process temperature is critical to increasing extraction yields and selectivity.

Application of an integrative system (2D PLE×HPLC-PDA) for bioactive compound extraction and online quantification: Advantages, validation, and considerations.

Analyzing compounds such as polyphenols in solid samples frequently uses a solid-liquid extraction step. The solid-liquid extraction and analysis integration in a single equipment is not commercially available since several challenges are inherent to this hybridization. In the context of developing more sustainable analytical procedures, innovative techniques are demanded. Given that, this work proposes a new integrative system (2D PLE × HPLC-PDA) and presents its validation for bioactive compound extraction and online quantification, discussing the main advantages and cares that need to be taken. Two food byproducts - passion fruit bagasse and coffee husks - were chosen as solid model samples. The system was configured to perform pressurized liquid extraction (PLE) with periodical automated extract injection in the HPLC, consequently obtaining the online quantification of target compounds from the solid samples. In parallel with the online injections, extract fractions were collected and submitted to offline analysis in which the extraction yield of piceatannol and chlorogenic acid and caffeine were evaluated, respectively, for passion fruit bagasse and coffee husks. The extraction yields obtained by online and offline injections were compared and were significantly equal (p > 0.05). Thus, the 2D PLE × HPLC-PDA system represents a feasible tool to integrate solid sample preparation and chemical analysis of biocompounds in a single and online step.

Hybrid flexible (HyFlex) teaching and learning: climbing the mountain of implementation challenges for synchronous online and face-to-face seminars during a pandemic.

In 2020, King's College London introduced HyFlex teaching as a means to supplement online and face-to-face teaching and to respond to Covid-19 restrictions. This enabled teaching to a mixed cohort of students (both online and on campus). This article provides an outline of how such an approach was conceptualized and implemented in a higher-education institution during an intense three-month period over that summer and prior to the limited re-opening of the university campus. This was a new approach that offers a number of pointers for reflection and provides key insights in on this novel learning environment and the physical and pedagogical contexts in which learning can occur. Technical implementation factors are detailed, along with both reflections on challenges and solutions. Pedagogical issues such as cognitive load, social presence, and resolving the issues of a cohort spread across two locations are discussed. While we should be mindful of the limitations of this relatively-specific research, and shouldn't therefore over-extrapolate our findings, one key finding is that delivering Hyflex is associated with a higher cognitive load. Further, the audio quality of our implementation enhanced the feeling of presence in the learning environment. We recommend providing appropriate technical and pedagogical training, as well as audio-visual and digital education support.

Simultaneous extraction and analysis of apple pomace by gradient pressurized liquid extraction coupled in-line with solid-phase extraction and on-line with HPLC.

Due to the complex characteristics and variable composition of apple pomace, sample preparation for chromatographic analysis is a great challenge. To solve this problem, we proposed using a solvent gradient using Pressurized Liquid Extraction (PLE), where the solvent gradually changes from water to ethanol during the extraction. Different dynamic gradients, static time, and temperatures were evaluated and showed relevant effects on the yields of target analytes. It was possible to improve extraction yields of compounds with different characteristics using the extraction solvent gradient. By coupling solid-phase extraction in-line, it was possible to separate compounds into fractions, where furfural, HMF, and chlorogenic acid gradually eluted from the adsorbent. At the same time, flavonoids were retained and eluted in the later fractions. On-line analysis by HPLC provided real-time information about the process and permitted the creation of a 3D chromatogram of the sample.

Insights on the Extraction and Analysis of Phenolic Compounds from Citrus Fruits: Green Perspectives and Current Status.

Citrus fruits (CF) are highly consumed worldwide, fresh, processed, or prepared as juices and pies. To illustrate the high economic importance of CF, the global production of these commodities in 2021 was around 98 million tons. CF's composition is considered an excellent source of phenolic compounds (PC) as they have a large amount and variety. Since ancient times, PC has been highlighted to promote several benefits related to oxidative stress disorders, such as chronic diseases and cancer. Recent studies suggest that consuming citrus fruits can prevent some of these diseases. However, due to the complexity of citrus matrices, extracting compounds of interest from these types of samples, and identifying and quantifying them effectively, is not a simple task. In this context, several extractive and analytical proposals have been used. This review discusses current research involving CF, focusing mainly on PC extraction and analysis methods, regarding advantages and disadvantages from the perspective of Green Chemistry.

Recent advances and trends in extraction techniques to recover polyphenols compounds from apple by-products.

Apple is one of the most consumed fruits worldwide and has recognized nutritional properties. Besides being consumed fresh, it is the raw material for several food products, whose production chain generates a considerable amount of by-products that currently have an underestimated use. These by-products are a rich source of chemical compounds with several potential applications. Therefore, new ambitious platforms focused on reusing are needed, targeting a process chain that achieves well-defined products and mitigates waste generation. This review covers an essential part of the apple by-products reuse chain. The apple composition regarding phenolic compounds subclasses is addressed and related to biological activities. The extraction processes to recover apple biocompounds have been revised, and an up-to-date overview of the scientific literature on conventional and emerging extraction techniques adopted over the past decade is reported. Finally, gaps and future trends related to the management of apple by-products are critically presented.