Effect of different cooking methods on the folate content, organoleptic and functional properties of broccoli and spinach

The effect of boiling, steaming, microwaving, cooking in a combi oven and using the sous-vide method under tested thermal conditions on the various properties of broccoli and spinach was evaluated. It was found that sous-vide reduced the total phenolic content to the lowest level and was the gentlest treatment due to the DPPH scavenging ability of spinach and broccoli extracts. Moreover, for folates, sous-vide cooking preserved these vitamer contents better than boiling for both vegetables but did not retain the green color of broccoli, as determined by C* (color saturation) and h° (hue angle). In broccoli samples, folate losses caused by sous-vide, microwave and cooking in a combi oven did not exceed 30%. The smallest decrease in the color tone parameter (h*) of broccoli and spinach was observed after microwaving. The same processing in spinach resulted in the highest color saturation (C*), and for both vegetables, it ensured the best sensory properties for general appearance, consistency and color.