Vol. 6, Issue 1, Part G (2017)
Extraction of antioxidant phytoconstituents from onion waste
Author(s): Varinder Singh, Pawan Krishan and Richa Shri
Abstract: Allium cepa L. is valued in traditional as well as modern systems of medicine. It is utilized as a major vegetable crop worldwide. However its use is plagued by generation of large quantities of outer scales discarded as waste. Literature shows that this leftover is rich in phenolic compounds. The present study aimed at establishing the most appropriate solvent for recovery of the antioxidant phenolic compounds. Different polar extracts were prepared and their total phenol content (TPC), total flavonoid content (TFC) and antioxidant activity were used as quality indicators to evaluate the extraction efficiency of the solvents. Distilled water extractive value was the highest (16.76 % w/w); while 70% methanol extract had the maximum TPC, TFC and DPPH scavenging activity (IC50 of 30.1µg/ml). Thus, methanol: water (70:30) may be used at laboratory scale as well as commercially to recover valuable phenolic compounds and flavonoids from onion waste.