Bioactive compounds are extracted from natural sources and they have beneficial effects on human health. Fruits and vegetables are rich in carotenoids, phenolic compounds, Vitamin C, among others. Extraction processes for these compounds depend on several factors such as the technique that is used, the raw material, and the organic solvent. Conventional techniques generally require large amounts of organic solvents, high energy expenditure, and are time consuming, which has generated interest in new technologies that are referred to as clean or green technologies. These can reduce or eliminate the use of toxic solvents, and thus preserve the natural environment and its resources. The aim of this review is to discuss recent techniques used to extract bioactive compounds from natural sources, in order to reduce the economic and ecological impact of these processes. Tecnologías verdes para la extracción de compuestos bioactivos en frutas y verduras RESUMEN Los compuestos bioactivos son extraídos de fuentes naturales y tienen efectos beneficiosos en la salud humana. Las frutas y verduras son ricas en carotenoides, compuestos fenólicos, vitamina C, así como en otras sustancias. Los procesos para extraer estos compuestos dependen de varios factores: la técnica utilizada, la materia prima y el solvente orgánico, entre otros. Además de ocupar mucho tiempo, las técnicas convencionales generalmente requieren grandes cantidades de solventes orgánicos y elevados gastos energéticos: ello ha generado interés en el uso de tecnologías nuevas, llamadas limpias o verdes. En tanto éstas pueden reducir o eliminar el uso de solventes tóxicos, permiten conservar el medio ambiente y sus recursos. El propósito de la presente revisión es examinar las técnicas empleadas recientemente para extraer compuestos bioactivos de fuentes naturales, con el fin de reducir el impacto económico y ecológico que conllevan estos procesos.
Osmotic dehydration and ultrasound are pretreatments used in order to reduce costs and processing time in the drying of food. We investigated the effect of the ultrasonic bath and an ultrasonic probe in osmotic solution, as a pretreatment of the drying process in an oven, for beet snacks. Different conditions of pretreatments (TP: ultrasonic probe treatment; TB: ultrasonic bath treatment) were performed and analyzed for water loss (WL) and solid gain (SG). After the snacks were ready, we evaluated the drying kinetics, aw, Brix, color, texture, and anthocyanin content. No difference was observed between treatments for SG and WL. The pretreatments TP5, TP10 and TB20 decreased by 22.2% the drying time in the oven. Regarding the snacks, there was no difference in texture. The colors of TP5, TP10, and TB10 were similar to the control, as well as the aw value of the TP5 and TP10. The TP5 had the highest anthocyanin content. The use of ultrasound probe in osmotic solution for 5 min, as a predrying treatment, is a viable technology as it reduces pretreatment and drying time without impairing the quality of the final product.
Practical applications
The use of ultrasound as a pretreatment in the drying of fruits reduces the drying time. Drying is an important process in obtaining new products, in addition to increasing shelf‐life.
The aim of this study was to evaluate the use of acid electrolyzed water, basic electrolyzed water, and slightly acidic electrolyzed water (AEW, BEW, and SAEW, respectively) as solvents in ultrasound (US) to extract bioactive compounds from Citrus reticulata. The influence of the intensity (17–85 W/cm2) and pulse cycles (0.5–1.0 dimensionless) was investigated in relation to the extraction of total phenolics (TP), total flavonoids (TF), and antioxidant activity (FRAP). The extract obtained with US + SAEW presented the highest values for TP (4,324.32 mg GAE.100/g of tangerine peel) and FRAP (663.69 µmol TEAC.100/g of tangerine peel). The highest TF content was found for US + AEW (691.76 mg EQ.100/g of tangerine peel). Response surface methodology showed that higher US intensities improved the extraction of phenolic compounds. Regarding the flavonoid compounds, the highest extractions were obtained at the central points (intensity (51 W/cm2) and cycle (0.75). The results showed that US and electrolyzed water successfully extracted bioactive compounds from tangerine peel; the processing time was also reduced by around 87.5%. These results were higher than those in the literature regarding conventional extraction techniques.
Practical applications
The combination of unconventional techniques (ultrasound and electrolyzed water as solvent) is characterized as a new methodology for the extraction of bioactive compounds from tangerine peel. This technique is environmental friendly due to the use of fruit residues, as well as the absence of organic solvents, and lower levels of energy use. The extract provided a higher content of total phenolics and total flavonoids than conventional methods. The extract can be incorporated into foods to provide nutritional quality and antioxidant properties. This technique is easily incorporated at the industrial level and is low cost after the purchase of the relevant equipment.
Antioxidant compounds were produced from submerged fermentation using Botryosphaeria dothidea. Sonication times (1-15 min) and agitations (0-150 rpm) applied to different fermentation phases (2-7 days) were evaluated for their effect on the broth antioxidant activity. In approximately 70% of assays performed with ultrasound, the antioxidant activity of the broth containing exocellular metabolites was higher than the control (without sonication), reaching a maximum value of 96%. The solid fraction (biomass after supernatant removal) corresponding to the best assay of antioxidant activity was submitted to extractions with water, ethanol or ethyl acetate to recover intracellular metabolites. The yields of extracts were 3.7 ± 2.6 wt %, 20.6 ± 3.9 wt % and 32.0 ± 4.2 wt % for ethyl acetate, ethanol and water, respectively. The use of ethanol could provide a larger number of compounds such as pentadecanoic acid, ergosta-5,8,22-trien-3-ol, and 1,4-diaza-2,5-dioxobicyclo [4.3.0] nonane. Both the supernatant and solid fractions revealed some bioactive compounds with promising antioxidant activity with the potential to replace some synthetic antioxidants.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.