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.

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