Food wastes phenolic compounds (PCs): overview of contemporary greener extraction technologies, industrial potential, and its integration into circular bioeconomy

Phenolic compounds (PCs) are abundant throughout the plant kingdom, which occurs in inexpensive resources, such as waste from food processing industries and agriculture activities. This has increased their extraction and subsequent utilization during the past few years. Natural phenolic compounds (Flavonoids and non-flavonoids) have grown more appealing from a technical standpoint, in addition to their usage in pharmaceuticals or as an additive in nutraceuticals, they also have potential in polymer technology. PCs have health-promoting qualities that can be attributed to their strong antioxidant activity and free radicals scavenging activity. These antioxidant properties protect against the action of oxidative species and are linked to the lower incidence of chronic non-communicable diseases such as diabetes mellitus, cardiovascular diseases, cancer, and neurodegenerative conditions. The extraction of phenols from food processing wastes has been studied using a variety of extraction procedures, most of which rely on the usage of organic solvents. Furthermore, there is currently a growing demand for environmentally friendly and affordable methods that produce polyphenol extracts with slightly harmful impacts on the environment. The employment of greener technologies like microwave-assisted extraction (MAE), deep eutectic solvent (DES) extraction, ultrasound-assisted extraction (UAE), supercritical fluid extraction (SFE), subcritical water extraction (SBWE), pressurized liquid extraction (PLE) and enzymatic extraction processes are examined in detail in this review which focuses on contemporary novel and feasible techniques for recovering useful PCs from food processing wastes. Further, how the greener extraction of PCs from food waste and its application in different industries can be integrated into a circular bioeconomy is also summarized.