Article History

Received 10 November 2019
Received in revised form 25 November 2019
Accepted 20 December 2019
Available online 30 December 2019


Onion, outer skin, quercetin, enzymatic synthesis, HPLC, UV-Vis, FTIR, NMR, DSC, TGA, SEM, antibacterial activity, toxicity..

Enzymatic Synthesis and Characterization of Quercetin Occurring in Onion (Allium cepa L.) Outer Skin

Rosalind Chakraborty1*, Arijit Chakraborty2, Md. Arman Ansari2, Sumanta Bhattacharya2 and Sparsa Moni Chatterjee3

1Department of Basic Science and Humanities, Supreme Knowledge Foundation Group of Institutions, Mankundu - 712139, Hooghly, West Bengal, India.

2Department of Textile Technology, Govt. College of Engineering and Textile Technology, Serampore – 712 201, Hooghly, West Bengal, India.

3Former Vice Chancellor, Indian Institute of Engineering, Science and Technology, Shibpur-711103, Howrah, West Bengal, India, currently Chairman, Board of Academic Affairs, Indian Institute of Handloom Technology, Chowkaghat- 221002, Varanasi, Uttar Pradesh, India.

*Corresponding author

ABSTRACT: The rapidly increasing trend of onion outer skin waste (OOSW) generation from the food industry compelling the scientists to search for possible ways of their utilization as it is not suitable for fodder in high concentrations. The best possible way could be to use these waste as a new and natural source of high value added products related to health benefits owing to the presence of flavonoids especially the powerful antioxidants, anti inflammatory, anti cancerous and colouring compound quercetin. For this, it is very essential to synthesize and characterize the quercetin occuring in OOSW. In this study, the quercetin was synthesized successfully from OOSW by Vacuum Assisted Soxhlet Extraction (VASE) method followed by enzymatic hydrolysis for purification. The purity study and structural characterization of synthesized quercetin were carried out by analyzing HPLC, UV-Visible, Fourior Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) (1H and 13C) spectra. Differential scanning Calorimetry (DSC), Thermo Gavimetric Analyzer (TGA) and Scanning Electron Microscope (SEM) were used for thermal and surface morphology characterization of quercetin. The results not only confirmed the structure of quercetin but also its thermal stability and smooth surface morphology with needle like regular shape profile. The antibacterial activity of quercetin in terms of zone of inhibition (ZOI) and bacterial reduction percentage was investigated against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The investigated quercetin showed good antibacterial activity and are found to be a promising non toxic material for use in food industry as packaging and in medical industry as medical material.


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