Vegetable sources and agro-industrial residues represent an important source of phenolic compounds that are useful in a wide range of applications, especially those with biological activities. Conventional techniques of phytochemical extraction have been associated with a high consumption of organic solvents that limits the application of bioactive extracts, leading to the implementation of novel extraction technologies using mechanisms such as Ultrasound Assisted Extraction (UAE). In the present review, an analysis of the involved variables in the extraction yield of phenolic compounds through UAE is presented, highlighting the advantages of this technology based on the results obtained in various optimized studies. A comparison with other technologies and a proposal of its possible application for agro industrial residues as raw material of phenolic compounds is also indicated. Finally, it is concluded that UAE is a technology that is placed within the area of Sustainable Chemistry since it promotes the use of renewable raw materials through the extraction of phenolic compounds, implementing the substitution of organic solvents with solvents that do not present toxic effects, lowering the energy consumption when compared to conventional methods and minimizing process times and temperatures, which is useful for the extraction of thermo-labile compounds.

Ultrasound assisted extraction for the recovery of phenolic compounds from vegetable sources

Phenolic compounds are broadly represented in plant kingdom, and their occurrence in easily accessible low-cost sources like wastes from agri-food processing have led in the last decade to an increase of interest in their recovery and further exploitation. Indeed, most of these compounds are endowed with beneficial properties to human health (e.g., in the prevention of cancer and cardiovascular diseases), that may be largely ascribed to their potent antioxidant and scavenging activity against reactive oxygen species generated in settings of oxidative stress and responsible for the onset of several inflammatory and degenerative diseases. Apart from their use as food supplements or as additives in functional foods, natural phenolic compounds have become increasingly attractive also from a technological point of view, due to their possible exploitation in materials science. Several extraction methodologies have been reported for the recovery of phenolic compounds from agri-food wastes mostly based on the use of organic solvents such as methanol, ethanol, or acetone. However, there is an increasing need for green and sustainable approaches leading to phenolic-rich extracts with low environmental impact. This review addresses the most promising and innovative methodologies for the recovery of functional phenolic compounds from waste materials that have appeared in the recent literature. In particular, extraction procedures based on the use of green technologies (supercritical fluid, microwaves, ultrasounds) as well as of green solvents such as deep eutectic solvents (DES) are surveyed.

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Bioactive Phenolic Compounds From Agri-Food Wastes: An Update on Green and Sustainable Extraction Methodologies.

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.

https://www.tandfonline.com/doi/pdf/10.1080/19476337.2017.1411978

Green technologies for the extraction of bioactive compounds in fruits and vegetables

Background Emulsion systems are widely applied in food industry. Several methods have been used for emulsion preparation. Among these methods, high intensity ultrasound (HIU) has attracted much attention because it is considered as an eco-friendly and cost-effective method. The acoustic cavitation phenomenon induced by HIU devices can boost the disruption of oil droplets, facilitating the formation of stable emulsions. Scope and approach This review briefly discusses the major differences between different emulsification devices and the mechanism of ultrasound emulsification process. In addition, emulsion preparation using different emulsifiers such as proteins, polysaccharides and surfactants has been covered in this review. The challenges and future trends of ultrasonic emulsification have also been discussed. Key findings and conclusions HIU could be used to improve the emulsifying properties of food emulsifiers such as proteins and polysaccharides and enhance the stability of their emulsions. Protein-polysaccharide complex stabilized emulsions produced by HIU showed better stability against environmental stresses than the emulsions stabilized by individual components. Moreover, several studies showed that HIU homogenizers were more energy efficient than high pressure homogenizers and microfluidizers. However, research cooperation between academic institutes and food companies is recommended to develop effective large scale ultrasonic devices.

Renata S. Rabelo

Papers

Sodium caseinate-corn starch hydrolysates conjugates obtained through the Maillard reaction as stabilizing agents in resveratrol-loaded emulsions

High internal phase emulsions (HIPE) using pea protein and different polysaccharides as stabilizers

Ultrasound assisted extraction and nanofiltration of phenolic compounds from artichoke solid wastes

Chitosan coated nanostructured lipid carriers (NLCs) for loading Vitamin D: A physical stability study.

Complexation of chitosan with gum Arabic, sodium alginate and κ-carrageenan: Effects of pH, polymer ratio and salt concentration