Changes in phytochemicals, anti-nutrients and antioxidant activity in leafy vegetables by microwave boiling with normal and 5% NaCl solution

The present study investigated the changes in phytochemicals and antioxidant activities in 25 leafy vegetables with two common boiling practices viz., with 5% NaCl solution (BSW) and normal water (BNW) in a domestic microwave oven. Fresh samples (100 g) were rich in polyphenols (58.8-296.9 mg), tannin (402.0-519.4 mg), flavonoids (148.9-614.4 mg), carotenoids (69.0-786.3 mg), anthocyanin (11.7-493.7 mg) and ascorbic acid (245.0-314.2 mg). Microwave boiling significantly (p < 0.05) decreased/increased phytochemicals but none of the compounds followed same trend in all vegetables. Boiling process reduced anti-nutrients from fresh samples (FS) as observed for nitrate (4.5-73.6% by BSW and 22.5-98.8% by BNW); phytate (6.2-69.7% by BSW and 10.6-57.3% by BNW) and oxalate (14.7-88.9% by BSW and 14.5-87.3% by BNW) but saponin increased in 18 vegetables by BNW while 8 vegetables by BSW. The study revealed differential pattern of change in phytochemical matrix and anti-nutrients in vegetables by microwave boiling which will help in devising efficient cooking practices and contribute in health and nutritional security.