Researchers at the University of Seville's Food Colour and Quality Laboratory have studied the effects of different cooking methods used for tomatoes and carrots (in the oven, microwave or air fryer, amongst others) on the amount of carotenoids that are potentially available for absorption by the body following the digestion of these foods. According to the study, the bioavailability index varies significantly depending on how these foods are cooked. Carotenoids are compounds of great importance due to their positive health effects.
In the case of carrots, the bioavailability of total carotenoids increased ninefold when cooked in the oven. For tomatoes, the highest bioavailability values were obtained by cooking them in either an air fryer (190 °C for 10 minutes) or a conventional oven (180 °C for 20 minutes). There was no significant differences between the two methods. Although the increase in bioavailability was more modest (a 1.5-fold increase), it was also significant compared to raw tomatoes.
The researchers also highlight that the increases in the bioavailability of the vitamin A precursor carotenoids in tomatoes (α-carotene and β-carotene) ranged from 26 to 38 times and 46 to 71 times, respectively, compared with those in raw carrots. Cooking is, therefore, a sometimes-overlooked strategy for combating vitamin A deficiency, one of the world's most serious nutritional problems.
Energy efficiency
The main innovation of these studies lay in identifying the cooking methods that led to the greatest increase in bioavailability per unit of electricity consumption. In the case of carrots, microwave cooking was found to be the most efficient technique, with a 96% reduction in electricity consumption compared to cooking in a conventional oven. In the case of tomatoes, cooking in an air fryer led to the highest bioavailability values, whilst also allowing an 80% reduction in energy consumption.
The results have recently been published in the journals Food & Function (2024) and Food Chemistry (2026) and provide experimental evidence to define the concept of 'sustainable cooking' from a nutritional and energy perspective. According to the researchers, if the concept were adopted and applied in millions of households and establishments on a daily basis, it could contribute significantly to a more sustainable food system.
Impact on public health and nutricosmetics
Carotenoids are compounds of great importance for promoting health. Some, such as α- and β-carotene, are precursors of vitamin A, an essential nutrient involved in a multitude of processes. Furthermore, both carrots and tomatoes are good sources of the colourless carotenoids phytoene and phytofluene. These have been attracting considerable interest due to their biological activities. They accumulate in the skin, where they can provide protection by absorbing ultraviolet radiation.
Source:
Journal reference:
Benítez-González, A. M., et al. (2026). Thermal processing of tomatoes by air frying and baking: effects on coloured and colourless carotenoid bioaccessibility. Food Chemistry. DOI: 10.1016/j.foodchem.2026.148311. https://www.sciencedirect.com/science/article/pii/S0308814626004693?via%3Dihub