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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.

The in-line coupling of the pressurized liquid extraction with a solid-phase adsorbent and a UV–Vis detector for the simultaneous extraction and separation of bioactive compounds from yerba mate (PLE-SPE-UV) was carried out in two stages. In the first stage, water was used as a solvent, while in the second stage, ethanol was used. For the optimization of the method, different adsorbents (Sepra C18-E, Isolute C18-EC, and Strata-X C18), temperatures (40–80 °C), solvent flow-rate (1–3 mL/min), and pH (4.0 and 8.0) were evaluated. By using a UV–Vis detector on-line, it is possible to monitor the process in real-time. The developed method allowed obtaining similar or higher recoveries of all the compounds classes than other methods, such as ultrasound-assisted extraction, stirring, maceration, and pressurized liquid extraction alone, in addition to separating them into fractions. The developed method could be used as sample preparation for the analysis of different compounds classes from mate.

Pomegranate (Punica granatum L.) has been used in traditional herbal medicine by several cultures as an anti‐inflammatory, antioxidant, antihyperglycemic, and for treatment and prevention of cancer and other diseases. Different parts of the fruit, extraction methods, and solvents can define the chemical profile of the obtained extracts and their biological activities. This study aimed to characterize the chemical profile of peel extracts collected using different extraction solvents and their biological effects on the cell cycle and apoptosis of THP‐1 leukemic cells. Aqueous extract presented the highest content of punicalagins (α pun = 562.26 ± 47.14 mg/L and β pun = 1,251.13 ± 22.21 mg/L) and the lowest content of ellagic acid (66.38 ± 0.21 mg/L), and it promoted a significant impairment of the cell cycle S phase. In fact, punicalagin‐enriched fraction, but not an ellagic acid‐enriched fraction, caused an S phase cell cycle arrest. All extracts increased the number of apoptotic cells. Punicalagin‐enriched fraction increased the percentage of cells with fragmented DNA, which was intensified by ellagic acid combination. The treatment combining punicalagin and ellagic acid fractions increased the apoptotic cleaved PARP1 protein and reduced the activation of the growth‐related mTOR pathway. Thus, these results evidence that solvent choice is critical for the phenolic compounds profile of pomegranate peel extracts and their biological activities., The main aim of this study was to assess and compare the differences in the chemical profile of pomegranate peel extracts obtained using different extraction solvents and how does it affect their biological properties.

Highlights • Apple by-products are a source of phenolic compounds associated with bioactivities. • Apple processing industries generate by-products that could be better used. • This work provides an up-to-date literature overview on extraction techniques. • Gaps and future trends related to apple by-products are critically presented., 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.

The comprehensive analysis of phenolic compounds from natural products comprises critical steps, including quantitative extraction, extract preparation, and chromatographic procedure. Performing these steps off-line requires a long time to obtain results, besides being laborious and more error-prone. This work discusses the concept and presents the details of assembling and validating a new system to comprehensively analyze phenolic compounds in natural products. The system is based on a bidimensional separation through the combination of pressurized liquid extraction with in-line solid-phase extraction coupled online with HPLC-PDA. The system proved to be able to perform a bidimensional separation to characterize the sample and ensure quantitative extraction of all detected components using the most appropriate extraction solvent gradient depending on the raw sample analyzed. The 1st dimension separation is achieved by PLE-SPE with a solvent gradient and differential interactions of extracted compounds with the adsorbent. The 2nd dimension presents the HPLC-PDA separation. The extraction/separation process can be monitored in real-time, and kinetic extraction curves for individual compounds can also be obtained to ensure quantitative extraction. Thus, the 2D PLE-SPE × HPLC-PDA may provide fast and precise comprehensive analyses of a large plethora of phenolic compounds, finding relevant applications in the chemical, food, pharmaceutical, and agricultural fields.

The objective of this work was the development of an on-line extraction/fractionation method based on the coupling of pressurized liquid extraction and solid-phase extraction for the separation of phenolic compounds from apple pomace. Several variables of the process were evaluated, including the amount of water of the first stage (0–120 mL), temperature (60–80 °C), solid-phase extraction adsorbent (Sepra, Isolute, Strata X and Oasis) and activation/elution solvent (methanol and ethanol). The best results were observed with the adsorbent Sepra. The temperature had a small effect on recovery, but significant differences were observed for phlorizin and a quercetin derivative. Results indicate that ethanol can be used to replace methanol as an activation, extraction/elution solvent. While using mostly green solvents (water, ethanol, and a small amount of methanol that could be reused), the developed method produced higher or similar yields of acids (2.85 ± 0.19 mg/g) and flavonoids (0.97 ± 0.11 mg/g) than conventional methods.

A Camellia sinensis é a planta mais usada para produção de chás nos dias atuais. Suas folhas são matéria-prima complexa, contendo diversos compostos fenólicos, sendo que tais substâncias têm demonstrado potencial para a prevenção e tratamento de doenças cardiovasculares e alguns tipos de câncer. O método de extração utilizado na preparação dos chás exerce grande influência no teor de substâncias extraídas, em especial os teores de compostos fenólicos e cafeína. No presente estudo, amostras de chá preto tiveram processo de extração analisado frente aos solventes água e solução de etanol 50%, às temperaturas de 40°C, 50°C, 60°C e sob as frequências de ultrassom de 37 kHz e 80 kHz. O teor de compostos extraídos foi quantificado pelos métodos FRAP (potencial antioxidante para reduzir sal férrico), TEAC (capacidade antioxidante do equivalente trolox) e fenólicos totais. A condição de extração com maior destaque foi etanol 50%, 60°C e 37 kHz, com FRAP de 1,9x10^4 μM FeSO4, TEAC de 2,0x10^4 μM Trolox e fenólicos totais de 2,1x10^3 μg/mL (ppm), seguida por etanol 50%, 50°C e 37 kHz, com FRAP de 1,8x10^4 μM FeSO4, TEAC de 1,9x10^4 μM Trolox e fenólicos totais de 2,3x10^3 μg/mL (ppm). A análise por cromatografia líquida de alta eficiência (HPLC) revelou que os extratos se constituem majoritariamente de ácido gálico, cafeína e flavonoides como quercetina, mirecetrina e keampferol.

A proposta deste estudo, consiste em analisar o enriquecimento de pães com extrato concentrado de erva mate e assim, produzir um alimento funcional. Através do processo de liofilização, será produzido um extrato seco, para que seja possível substituir a farinha de trigo da formulação tradicional em diferentes níveis (0,5%; 1,0%; 1,5%; 2,0% e 2,5%). Estas quantidades foram propostas com base em testes preliminares. Inicialmente será realizada a análise do extrato seco e posteriormente, será analisado o produto (pão) antes e depois da cocção. São realizados procedimentos que avaliam o teor de fenólicos e a atividade antioxidantes destes. Além disso, são realizadas análises: por cromatografia líquida, centesimal e das propriedades físicas dos pães (cor, volume e textura), além da análise sensorial, buscando identificar os níveis máximos de inclusão do extrato de mate, sem afetar sua aceitação.A proposta deste estudo, consiste em analisar o enriquecimento de pães com extrato concentrado de erva mate e assim, produzir um alimento funcional. Através do processo de liofilização, será produzido um extrato seco, para que seja possível substituir a farinha de trigo da formulação tradicional em diferentes níveis (0,5%; 1,0%; 1,5%; 2,0% e 2,5%). Estas quantidades foram propostas com base em testes preliminares. Inicialmente será realizada a análise do extrato seco e posteriormente, será analisado o produto (pão) antes e depois da cocção. São realizados procedimentos que avaliam o teor de fenólicos e a atividade antioxidantes destes. Além disso, são realizadas análises: por cromatografia líquida, centesimal e das propriedades físicas dos pães (cor, volume e textura), além da análise sensorial, buscando identificar os níveis máximos de inclusão do extrato de mate, sem afetar sua aceitação.Os resultados demostram, que a concentração inicial de fenólicos na massa crua foi de 0,764 mg Ác. Gálico/g de pão, isto em relação ao pão que substituiu 1% da farinha de trigo pelo extrato de mate. Após o cozimento observou-se um aumento na concentração no pão (0,969 mg Ác. Gálico/g de pão), que pode ter sido provocado pela evaporação da água utilizada na formulação. Os resultados sugerem que a maior parte dos compostos presentes resistem ao processamento térmico e que o extrato de mate tem um enorme potencial para o enriquecimento de pães com os consequentes benefícios à saúde.

In this study it is proposed the introduction of an expansion gas in high pressure water to maximize the cavitation caused by the application of ultrasound to improve the extraction of phenolic compounds from pomegranate peel. Different combinations of ultrasound power (US-Pwr), expansion gas initial pressure (N2-Pi), system pressure (SP) and particle size of sample were evaluated using water as solvent. The use of US-Pwr and N2-Pi individually or combined improved the extraction process proving higher yields. SP was an important parameter affecting extraction yield, showing an inverse relation between its increase and extraction yield. Although higher yields were produced with samples with smaller particles, the combination of ultrasound and expansion gas had a positive effect on the process independently of particle size, promoting an increase of 20-26% in yield. These results suggest an enormous potential to be explored with the introduction of an expansion gas in pressurized liquids in processes assisted by ultrasound for the extraction of phenolic compounds from natural products using green solvents.

The objective of this work was to evaluate the on-line coupling of pressurized liquid extraction with an adsorbent for the simultaneous extraction and separation of flavonols of black tea, producing a concentrated extract that could be used as ingredient for the production of functional bakery products. After the evaluation of different adsorbents, extraction temperatures and solvents, a two-stage process was developed which was capable of producing three extracts: one with high concentration of gallic acid (78.97 ± 5.49 mg/L), another one with high concentration of caffeine (109.72 ± 3.15 mg/L) and a highly concentrated flavonol extract (322.0 ± 4.50 mg/L). The developed method uses greener solvents (water and ethanol) and is capable of producing higher flavonol (~50%) yields than conventional methods. The introduction of the flavonol extract in the dough can be used for the development of functional bakery since compounds were stable under processing conditions.

The combination of ultrasound and pressurized liquid extraction (UAPLE) was evaluated for the extraction of phenolic compounds from pomegranate peels (Punica granatum L.). The influence of several variables of the process on extraction yield, including solvent type (water, ethanol + water 30, 50 and 70% v:v), temperature (50–100 °C), ultrasound power (0–800 W at the generator, or 0–38.5 W at the tip of the probe), mean particle size (0.68 and 1.05 mm), and number of cycles (1–5), were analyzed according to the yield of 20 different phenolic compounds. The most suitable temperatures for the extraction of phenolic compounds using water were from 70 to 80 °C. In general, 100 °C was not adequate since the lowest extraction yields were observed. Results suggested that ultrasound had a greater impact on extraction yields using large particles and that intermediate ultrasound power (480–640 W at the generator, or 23.1–30.8 W at the tip of the probe) produced the best results. Using small particles (0.68 mm) or large particles (1.05 mm), extraction with ultrasound was 1 cycle faster. Ultrasound may have offset the negative effect of the use of large particles, however, did not increase the yield of phenolic compounds in any of the cases studied after five cycles. Additionally, the continuous clogging problems observed with small particles were avoided with the use of large particles, which combined with ultrasound allowed consistent operation with good intra and inter-day reproducibility (>95%). Using samples with large particle size, the best extraction conditions were achieved with water extraction solvent, 70 °C extraction temperature, ultrasound power at 480 W, and 3 cycles, yielding 61.72 ± 7.70 mg/g. UAPLE demonstrated to be a clean, efficient and a green alternative for the extraction of phenolic compounds from pomegranate peels. These findings indicate that UAPLE has a great potential to improve the extraction of bioactive compounds from natural products.