Green, environment-friendly and sustainable techniques for extraction of food bioactive compounds and waste valorization

Fruits and vegetables are rich sources of highly beneficial bioactive compounds traditionally used for healing purposes. These bioactives are recently being used for large-scale applications such as nutraceuticals and functional foods. The flesh of the fruit/vegetable and the processing wastes such as peels and seeds have been found to have large amounts of bioactive compounds. The fruit and vegetable processing waste such as pomace, peels, leaves, and seed fractions are potential feedstock for extraction, separation, and recovery of bioactive compounds such as polyphenols, flavonoids, pigments, pectin, essential oils, etc. The untapped potentials (antioxidant, antibacterial, anti-inflammatory, etc.) of these bioactive-rich waste have inspired researchers to carry out studies in an innovative way to extract these valuable compounds. Numerous conventional methods for the extraction of bioactives from waste are in practice. However, greener and eco-friendly techniques are more desirable than conventional ones for extraction process intensification. The emerging green extraction methods provide a potential tool to isolate bioactive molecules from the wastes of fruits and vegetables. However, numerous parameters such as sample, energy and cost requirement, environmental impact, and resultant extract quality decide the suitable extraction technique. The green extraction processes have the potential to permit ease for scaling up to industrial extraction. The reviewed examples in this paper demonstrate the capability of green extractions to conquer the technology readiness level (TRL) of 6–8, with the further expansion toward the scaling up, which looks commercialization as a driving force.