Screening of short-day onion cultivars of India for vitamin-C content

Abstract

Onion has been used to cure various health problems and has many functional and therapeutic values. Its bulbs are a rich source of sulphur-containing organic compounds, minerals, vitamins, etc. However, value of onion bulbs as a source of vitamin C specifically is undervalued. Vitamin C or ascorbic acid is an indispensable constituent of all living cells and tissues for various metabolic functions and as a strong antioxidant to mitigate oxidative stress. For quantification of ascorbic acid, forty-five short-day Indian commercial varieties representing white to red bulb colour were used for the present study. A highly significant variation in the concentration of ascorbic acid among genotypes was observed. The ascorbic acid concentration in raw bulbs ranged from 4.94 to 45.05 mg/100 g on a fresh weight (FW) basis, whereas, it varied from 59.51 to 173.56 mg/100 g on a dry weight (DW) basis. Variations in ascorbic acid amount were noted among bulb colour. White onion exhibited lower concentration compared to red coloured varieties. As per the recommendation of ICMR, one hundred grams of raw onion bulb of variety containing the highest ascorbic acid could supply 85-90% of the recommended daily allowance (RDA) of vitamin C to adults per day. This information would also be of great help for future breeding programs to develop new cultivars possessing higher amounts of ascorbic acid to ensure nutritional security in India.