Effect of superheated steam and conventional steam roasting on nutraceutical quality of several vegetables

The superheated steam technology (SHST) is a heat treatment that involves a heated saturated steam. To date, the use as cooking technology has not been evaluated in depth in terms of retention of phytochemicals. In this study, the use of SHST was compared with a conventional saturated steam (CS) oven in order to evaluate their impact on different vegetables (tomato fruits, spinach leaves and artichoke inflorescences). At biochemical level, phenolic compounds, total ascorbic acid content, some specific antioxidant compounds and, consequently, the antioxidant activity have been evaluated. Results reported a decrease of bioactivity in the tomato cooked samples (in both the heat treatments) when compared with the fresh sample. Instead, spinach leaves and artichoke inflorescences reported an increase of phytochemicals and antioxidant activity in CS or SHS samples when compared with fresh ones. Few differences in the content of bioactive compounds were observed after the use of the CS or SHS technology. Further analyses are required to verify the differences between the use of superheated or conventional steam on vegetables.