1. SCREENING AND PROFILING OF ONTARIO GROWN ONION VARIETIES FOR ITS ANTIOXIDANT PROPERTIES
Cynthya Maria Manohar, Jun Xue, Abdul Murayyan, Suresh Neethirajan*, John Shi
BioNano Lab, School of Engineering
INTRODUCTION
Diabetes, Cardiovascular diseases and Cancer especially breast cancer in women (leading cause of cancer death) – major health concern in North America [1].
Naturally occurring plant compounds such as phenolics scavenges free radicals and inhibit reactive oxygen species, thereby preventing the damage to lipids, proteins and nucleic acids.
Onions are rich source of flavonoids and possess high level of antioxidant activity.
Low polarity water technology and solvent extraction are two techniques involved to isolate flavonoids from onions.
Identification and analyzation of the extracted flavonoids is performed by High-performance liquid chromatography (HPLC).
Antioxidant assays such as DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid), Oxygen radical absorbance capacity (ORAC), hydrogen peroxide scavenging activity are few assays which measures the total antioxidant activity.
RESULTS
HIGH PERFORMANCE LIQUID CHROMATOGRAPHY (HPLC) CURVE PLOTTED IN TIME Vs NORMALIZED AREA CURVES
HPLC showing peaks of quercetin, quercetin 7, 4'-diglucoside, kaempferol, isohamnetin and anthocyanins such as cyanidin 3-(6"-malonylglycoside) delphinidin 3- glucosude, delphindin aglycon and petunidin (glucosylglucoside)
OBJECTIVES
The overall goal of this project is to screen Ontario grown onion varieties for its antioxidant properties and use the correct variety to develop functional food traits.
Experimental workflow
TOTAL POLYPHENOLIC CONTENT
TOTAL FLAVONOID CONTENT
Ruby Ring onion variety found to have the highest phenolic content (p<0.05) at 1.95± followed by Stanley at 1.69 ±0.13.
Stanley onion variety found to have the highest flavonoid content (p<0.05) at 1.02±0.011 followed by Ruby Ring at 0.897±
ANTIOXIDANT ASSAY
DPPH (2,2-diphenyl-1-picrylhydrazyl)
The highest DPPH radical scavenging activity was observed from Ruby Ring (21.52±1.3%) followed by Lasalle (15.46±3.88%).
CONCLUSIONS
Total phenolic and flavonoid contents showed significant variation among the 5 varieties.
Ruby Ring red onion variety showed the best DPPH scavenging activity.
Identification, enhancement and development of market quality traits such as antioxidants properties of Ontario-grown onions will enhance their marketability as nutraceutical products, as natural antibiofilm coating agents for improved shelf life of packaged food and as a preservative in processed food.
REFERENCES
[1] Hui, C., Qi, X., Qianyong, Z., Xiaoli, P., Jundong, Z., & Mantian, M. (2013). Flavonoids, flavonoid subclasses and breast cancer risk: a meta-analysis of epidemiologic studies. PLoS One, 8(1), e54318.
[2] Yang, J., Meyers, K. J., van der Heide, J., & Liu, R. H. (2004). Varietal differences in phenolic content and antioxidant and antiproliferative activities of onions. Journal of agricultural and food chemistry, 52(22),
[3] Do Thi, N., & Hwang, E. S. (2014). Bioactive Compound Contents and Antioxidant Activity in Aronia (Aronia melanocarpa) Leaves Collected at Different Growth Stages. Preventive nutrition and food science, 19(3), 204.
ACKNOWLEDGMENTS
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