<p>Dry matter (%) of raw and cooked vegetables.</p>

Flavonoid levels declined mainly under high-water boiling but remained stable in purslane. Tannin-associated phenolic compounds decreased in nettle and sorrel during boiling, whereas purslane exhibited increases across several treatments. Antioxidant capacities generally decreased with high-water boiling, while steaming and microwaving preserved or enhanced DPPH and CUPRAC activity in purslane.

Strong correlations were observed between total phenolic content and antioxidant assays (r = 0.853–0.956). Overall, steaming and microwaving were identified as the most effective techniques for retaining phenolic compounds and antioxidant capacity, whereas high-water boiling caused the greatest losses. These findings highlight the importance of selecting appropriate cooking methods to preserve the nutritional quality of leafy vegetables.</p></div>