Towards more sustainable cooking practices to increase the bioaccessibility of colourless and provitamin A carotenoids in cooked carrots†

The effect of different cooking methods (boiling, baking, steaming and microwaving) on the colour and texture of carrots, as well as on the bioaccessibility of carotenoids, was investigated in order to identify the more “sustainable cooking” methods. Cooking resulted in statistically significant increases in total carotenoid bioaccessibility, both with intensity and duration of treatments. In particular, significant increases in carotenoid bioaccessible content (CBC) were observed, ranging from 6.03-fold (microwave) to 8.90-fold (baking) for the most intense cooking conditions tested. Although the relative concentration of the colourless carotenoids (phytoene and phytofluene) in raw carrots is lower than that of provitamins A α- and β-carotene, the bioaccessible content of the colourless ones is much higher. From an energy consumption standpoint and considering samples with the same tenderness, the highest CBC values per kWh decreased in the order microwaving > baking > water cooking > steaming. Our findings are important to help combat vitamin A deficiency since increases of up to ∼40-fold and ∼70-fold in the CBCs of the vitamin A precursors α- and β-carotene, respectively, were observed. These results provide a basis for defining “sustainable cooking” as “cooking practices that optimize intensity, duration and other parameters leading to a more efficient use of energy to maximize the bioavailability of nutrients and other beneficial food components (such as bioactives) while ensuring food appeal and safety”.