Interest in phenolic compounds has recently increased due to their potential as antioxidant agents. Moringa leaves (Moringa oleifera) have a high content of phenolic compounds, which presents them as a promising source for the extraction of these compounds. However, it is necessary to use analytical techniques to identify and quantify their actual compound content to determine the quality of the raw material and the potential of the final product. Ultrasound assisted extraction is a green, rapid and environmentally friendly extraction technique that produces high quality extracts from natural products. Hence, the aim of this research is to optimize the variables of the ultrasound-assisted extraction (UAE) process for the extraction of moringa leaves using response surface methodology (RSM) to extract the main flavonoids using methanol as the extraction solvent. A Box–Behnken design (BBD) has been used to evaluate the effect of the ultrasound extraction process variables. Finally, the optimal extraction time in the range between 2 and 30 min was determined. The results revealed that the methanol concentration was the most influential variable. The optimal extraction time was established at 15 min. Six of the main flavonoids were quantified by UHPLC-DAD and identified by UHPLC-QToF-MS. The results confirmed that UAE is an efficient method for the extraction and subsequent analysis and quality control of the flavonoids that can be found in moringa leaves.

Supercritical fluid extraction (SFE), using CO₂, is a novel, sustainable and very efficient technique for the recovery of highly apolar compounds. However, the recovery of phenolic compounds requires the use of different co-solvent combinations such as water and ethanol to enhance the recovery of these compounds through the optimization of a number of variables. In this sense, the effect of pressure (100, 150 and 200 bar), temperature (50, 65 and 80 °C), extraction time (30, 60, 90, 120, 150 and 180 min) and the effect of the different percentages of ethanol and water as co-solvents on the composition and phenolic content of moringa leaf extracts were evaluated. Six major flavonoids were identified by ultra-high-performance liquid chromatography coupled to a quadrupole-time-of-flight mass spectrometer (UHPLC-Q-ToF-MS). Pressure and temperature had a significant effect on the phenolic composition of the extracts, as well as on their concentrations. The highest concentration of total flavonoids compounds (TFCs) was obtained by using a mixture of CO₂ and water of 50:50 (v/v) at 100 bar, at 65 °C after a 120 min extraction time that produced a concentration of 11.66 mg ± 0.02 mg TFC g⁻¹ sample, which corresponds to 89.0% of the total flavonoids of the sample, obtained by exhaustive extraction.

The goal of this study is to optimize a UAE method for the extraction of the main bioactive compounds present in the ginger rhizome (gingerols and shogaols). Ginger rhizome (Zingiber officinale) has a considerable content of bioactive compounds, in particular gingerols and shogaols, with interesting pharmacological activities such as anti-inflammatory, antioxidant, anti-cancer, and antimicrobial properties, among others. The isolation of these compounds requires an efficient extraction process with short extraction times and the employment of specific non-toxic solvents for humans. In this work, the optimization of an ultrasound-assisted extraction (UAE) method for the extraction of the main pungent compounds in the ginger rhizome, i.e., gingerols and shogaols, has been carried out. For this purpose, a Box–Behnken design (BBD) has been used to optimize the experimental design through a response surface methodology (RSM). The percentage of ethanol in the extraction solvent, the temperature, the amplitude, and the cycle of the ultrasounds, as well as the sample-to-solvent ratio, were the variables to be studied. Thus, the percentage of ethanol in the extraction solvent was identified as the most influential factor. Once the compounds were extracted, the identification of gingerols and shogaols was performed by ultra-high-performance liquid chromatography (UHPLC) coupled to a quadrupole-time-of-flight mass spectrometer (Q-ToF-MS), and the quantification by UHPLC coupled to a diode array detector (DAD) detector. Finally, the optimized UAE method required only 10 min of extraction time, presenting good repeatability and intermediate precision levels (<5%). The method was applied to extract gingerols and shogaols from diverse sources, thereby demonstrating its applicability and highlighting the potential variations in compound concentrations across different samples based on factors such as origin, and growing conditions, among others.

Ginger (Zingiber officinale Rosc.) is a plant recognized for its pungent taste and aromatic qualities, primarily derived from its underground rhizome. Apart from its widespread culinary applications, ginger is valued for its potential health benefits attributed to the presence of gingerols and shogaols. For this reason, this work proposes the development of a microwave-assisted extraction (MAE) method for the extraction of gingerols and shogaols present in ginger rhizomes. The influence of the extraction temperature (50–100 °C), the solvent composition (50–100% ethanol in water), and the sample-to-solvent ratio (0.3–0.7 g sample: 20 mL) on the extraction of these bioactive compounds has been studied. To this end, a Box–Behnken experimental design (BBD) in combination with a response surface methodology (RSM) has been applied. The optimum conditions for the total extraction of gingerols and shogaols were: 87% ethanol in water, 100 °C, and 0.431 g of ginger sample in 20 mL solvent. The developed method required short extraction times (5 min) and demonstrated favorable levels of repeatability and intermediate precision (CV < 5%). Finally, the MAE method was successfully used for the extraction of gingerols and shogaols from a variety of ginger samples.

In this study, we performed supercritical CO₂ extraction of oleoresin from Peruvian ginger, focusing on the extraction yield, total polyphenol content, antioxidant capacity, and contents of gingerol and shogaol. The temperature (40 to 50 °C), pressure (80 to 250 bar), CO₂ flow rate (2 and 8 ft³/h) and extraction time (10 to 360 min) were evaluated in three steps. The extraction yield was influenced by the temperature, pressure, flow rate and extraction time. Oleoresin extracts were obtained from 150 to 250 bar. The supercritical extraction conditions selected for the recovery of the oleoresin extract were 50 °C, 250 bar, 8 ft³/h and 360 min, resulting in an extraction yield of 25.99 ± 0.13 mg extracts/g dry basis, a total polyphenol content of 171.65 ± 2.12 mg of gallic acid equivalent (GAE)/g extract, an antioxidant capacity expressed as a half-maximal inhibitory concentration (IC₅₀) of 1.02 ± 0.01 mg extract/mL methanol and a Ferric Reducing Antioxidant Power (FRAP) value of 368.14 ± 60.95 mg Trolox/g extract. The contents of gingerols and shogaols in the supercritical extract were 254.71 ± 33.79 mg of 6-gingerol/g extract, 24.46 ± 3.41 mg of 6-shogaol/g extract, 9.63 ± 2.51 mg of 8-gingerol/g extract, 51.01 ± 9.39 mg of 8-shogaol/g extract, 27.47 ± 5.06 mg of 10-gingerol/g extract and 20.11 ± 4.62 mg of 10-shogaol/g extract. There was no reduction in the total polyphenol content or antioxidant capacity according to the IC₅₀ and FRAP assays, under storage conditions of 0 °C, 20 °C and 40 °C after 180 days; this indicates that the oleoresin obtained using supercritical CO₂ extraction could be used as an additive in food products.