Physicochemical composition and antioxidant capacity of zucchini and green beans before and after steaming and boiling

ABSTRACT Different cooking methods can be used to prepare vegetables, therefore, understanding the effect of these techniques on food composition is necessary. The aim of this study was to determine the effect of cooking on the physicochemical composition of zucchini and green beans. Three treatments were considered: raw, steamed and boiled foods. For each treatment, the experiment was performed with six replicates and each sample unit was analyzed in triplicate. The analyses performed were: cooking factor, soluble solids, pH, moisture, ash, phenolic compounds and antioxidant capacity. Significant data of the treatments were analyzed by Tukey's test. The foods showed cooking factor equals to one. Both boiled zucchini and green beans showed the lowest contents of soluble solids, ash and phenolics. The moisture content of both vegetables decreased after cooking. The steamed foods presented the highest antioxidant capacity. Considering pH, the boiled zucchini presented the lowest level and both thermal processes increased the pH of the green beans. We concluded that steaming preserves or improves the composition of the foods analyzed in the present study.