Extraction and characterization of polyphenols from fruits and vegetable waste through green extraction technologies with special reference to antioxidant profile

Food insecurity is deemed as one of the biggest challenges faced by the developing economies and Pakistan is no more exception. Moreover, the food waste further amplified the scarcity. The utilization of food waste is considered as one of the prime strategies to support the circular economy and food security. The mandate of the current investigation was to extract and characterize the polyphenols from selected fruits and vegetable waste via green extraction technologies. Purposely, banana, orange, apple, onion, and garlic processing industry by-products (peel& husk) were collected and subjected to compositional analysis followed by nutritional profiling with special reference to minerals. Later, the antioxidants from the studied peel were extracted by adapting the supercritical and ultrasound added extraction techniques alongside conventional extraction. The results indicated that the tested peels exhibited a promising amount of fiber and protein alongside K, Mg, iron, sodium, and calcium. Among the extraction modules, supercritical at 3000 psi elucidated the highest total phenolic contents (TPC), total flavonoids (TF), DPPH, FRAP, ABTS activities as 473.73 +/- 23.6 mg GAE/100 g, 126.39 +/- 9.54 mg CE/100 g, 53.81 +/- 3.82 (%), 22.24 +/- 0.25 mu M Fe+2/g, and 12.14 +/- 0.15 mu M TE/g, respectively followed by ultrasound and conventional extraction. Among the peels, onion peel showed the highest antioxidant activity as 914.44 +/- 39.4 mg GAE/100 g) 178.19 +/- 14.5 mg CE/100 g, 82.47 +/- 5.48%, 30.22 +/- 0.19 mu M Fe+2/g, and 17.33 +/- 0.26 mu M TE/g for TPC, TF, DPPH, FRAP, and ABTS, respectively. Novelty impact statement The current investigation is a unique effort to valorize the fruits and vegetable waste through green extraction technologies in Pakistan. No doubt, fruits and vegetable waste are explored earlier; however, the application of different novel/green technologies for the extraction of biomolecules from waste is limited. Outcomes delineated that the fruits and vegetable peels exhibited promising nutritional and antioxidant profiles. The extraction module and processing parameters significantly (p <= 0.05) affected the extraction yield and antioxidant indices. It is also worth mentioning that the supercritical fluid extraction caused a pronounced effect followed by ultrasound added extraction as compared with conventional extraction.