Antioxidant properties of two varieties of bitter gourd (Momordica charantia) and the effect of blanching and boiling on them

The antioxidant properties of whole fruits and fruits without seeds and pith of two varietiesof Momordica charantia (commonly known as bitter gourd), var. minima and var. maxima were investigated. The antioxidant content was investigated using ascorbic acid and total phenolic contents whereas the antioxidant activity was investigated using 2,2-diphenyl-1-picryl hydrazyl radical scavenging activity and ferrous ion chelating activity. The results showed that the fruits without seeds and pith and whole fruits of the two varieties of Momordica charantia exhibited different antioxidant content and activities. The ascorbic acid content ranged from 8.12 mg/100g to 24.46 mg/100g whereas the total phenolic content ranged from 1.47 mg GAE/100g 27.23 mg GAE/100g. The antiradical power ranged from 4.67 to 5.94 and the ferrous ion chelating activity using the fruit extract concentration of 0.34 g/mL ranged from 10.6 to 89.3 . The effect of blanching and boiling on the antioxidant properties of fruits without seeds and pith of Momordica charantia var. maxima and minima was also investigated. Blanching and boiling of fruits without seeds and pith of M. charantia var. maxima and var. minima induced changes in the antioxidant content differently. The radical scavenging activity of the fruits without the seeds and pith of M. charantia var. maxima and var. minima increased as a result of blanching and boiling but their ferrous ion chelating activity became undetectable. There was no clear correlation between the antioxidant content and the antioxidant activities.