Marcelo M.R. de Melo

Environmentally Benign Supercritical Fluid Extraction

Abstract Supercritical fluid extraction (SFE), and in particular supercritical carbon dioxide (SC-CO2) extraction, is an environmental-friendly high-pressure extraction technology alternative to conventional solid–liquid extraction. The use of SC-CO2 can provide valuable industrial advantages such as intensification and simplification of the processes, with consequent savings on chemicals, utilities and processing time. Moreover, it may preserve the natural character of the products and even act as enhancer of composition and properties such as antioxidant activity, shelf life, cooking time, etc. Prospective novel applications are expected to emerge at industrial scale in the coming years, extending the valences and scope of SFE and SC-CO2 to novel fields. These topics are addressed in this chapter.

Emerging technologies for the recovery of valuable compounds from coffee processing by-products

Abstract Spent coffee grounds (SCG) and coffee silverskins (CSS) are two high-volume industrial by-products rich in valuable components, such as alkaloids, diterpenic, and phenolic compounds, triglycerides (oils), and polysaccharides. Their recovery yield and purity are highly dependent on the selected extraction method and operating conditions. This chapter discusses recent advances on the following separation technologies: solid–liquid extraction (SLE) using conventional solvents and ionic liquids, supercritical fluid extraction (SFE), subcritical water extraction, ultrasound assisted extraction, and microwave assisted extraction. SLE and SFE are the most mature approaches for the extraction of coffee by-products, although promising results have been reported for the other technologies. Solvents like ionic liquids (ILs) and deep eutectic solvents are expected to play an important role in the near future, along with other approaches, such as pervaporation, nanofiltration, sorption (adsorption and ion exchange), hydrothermal liquefaction, pulsed electric fields extraction, and products synthesis under the scope of nanotechnology. Overall, these methods produce oils/extracts rich in phenolic compounds exhibiting valuable antioxidant activity levels, with encouraging extraction yields. The optimization of both operating conditions and unit’s arrangement is crucial to ensure their technological and economic viability. Currently, a considerable number of scientific studies and patents demonstrate or claim their use for various applications, including dermatological formulations, pest control formulations, growth enhancer substrates for bacterial cultures, biodiesel production, among others.