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

• Published in: Food chemistry Vol. 176; pp. 244 - 253
• Main Authors: Singh, Shrawan, Swain, S., Singh, D.R., Salim, K.M., Nayak, Dipak, Roy, S. Dam
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2015
• Subjects: Andaman and Nicobar Islands; Anthocyanins - analysis; Anti-nutrients; Antioxidants - pharmacology; DPPH activity; Flavonoids - analysis; Microwave boiling; Microwaves; Phenols - analysis; Phytochemicals; Phytochemicals - analysis; Plant Leaves - chemistry; Sodium Chloride - pharmacology; Tannins - analysis; Traditional vegetables; Vegetables - chemistry; DPPH activity; Phytochemicals; Microwave boiling; Anti-nutrients; Traditional vegetables; Andaman and Nicobar Islands
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2014.12.068

•Microwave boiling affected the phytochemical constituents in traditional vegetables.•Individual vegetables showed different pattern of phytochemical changes.•Ionic (Na++/Cl−) changes in boiling media influenced phytochemical matrices.•Anti-nutrients (except saponin) reduced by boiling in vegetables. 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 (100g) were rich in polyphenols (58.8–296.9mg), tannin (402.0–519.4mg), flavonoids (148.9–614.4mg), carotenoids (69.0–786.3mg), anthocyanin (11.7–493.7mg) and ascorbic acid (245.0–314.2mg). 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.