A fast and simplified method to estimate bioaccessibility of carotenoids from plant tissues

Carotenoids are lipophilic isoprenoids with roles in photosynthesis and signaling. Dietary carotenoids are nutritionally relevant as precursors of retinoids (including vitamin A). These pigments also provide health benefits as anti-oxidative, anti-inflammatory or anti-tumor agents, among other biological functions. Such health-related advantages have spurred a strong interest in the biofortification of food products with carotenoids. Most biotechnological approaches have been carried out in plants because dietary carotenoids are primarily obtained from fruits and vegetables. Successful examples abound in the literature but in most cases a critical aspect is neglected: bioaccessibility. A higher content of carotenoids in a given plant product does not necessarily mean an improved dietary intake because these lipophilic compounds must be released from the food and incorporated into intestinal micelles to reach the sites of action in the human body. Bioaccessibility refers to the percentage of the carotenoid that is released from the food matrix during digestion and incorporated into micelles in the gastrointestinal tract. Bioaccessibility substantially changes depending on the physicochemical context and subcellular environment where carotenoids accumulate within plant cells. Here, we present a fast, simplified, inexpensive and efficient in vitro method to estimate bioaccessibility that has been adapted to the requirements and equipment of typical plant molecular biology labs. The availability of this protocol should improve biotechnological efforts aimed at carotenoid biofortification by complementing compositional improvements with bioaccessibility data to better estimate the nutritional value of the newly generated functional food.