Tomato carotenoids processing during simulated digestion: stability and transfer between tomato particles from Hot Break and Cold Break tomato purée, emulsion and mixed micelles

<strong>Introduction</strong>. The process of digestion of plant food matrix could modulate the bioaccessibility of nutritionally relevant lipophilic micronutrients like carotenoids. Different steps are: diffusion of carotenoids into an oil phase, which also depends on food processing, transfer of carotenoids either into emulsion (gastric digestion) or inside micelles (intestinal digestion), possible degradation through oxidation. To better understand the factors limiting the bioaccessibility of carotenoids, we investigated their stability and their kinetics of transfer in experimental models mimicking digestion, i.e. from tomato particles to emulsions and mixed micelles and from emulsions to mixed micelles. <strong>Materials and Methods</strong>. Oil-in-water emulsions, mimicking those in the gastric compartment, were elaborated and characterized. Main carotenoids present in food (i.e. β-carotene, lycopene and lutein) were incorporated into these emulsions and we measured the emulsion droplet size and their stability as well as the stability of carotenoids during 4 hours at 37°C in the dark and room pressure. Transfer of carotenoids to mixed micelles was studied for carotenoid-enriched emulsions and also for tomato particles, prepared from tomato purée produced either by cold break (CB) or hot break (HB) tomato processing. <strong>Results and Discusson</strong>. Carotenoids did not modify neither mode nor size distribution of emulsion lipid droplets. No significant change in the total carotenoid concentration was observed during the transfers but a 3–8% isomerization of the carotenoids. 吀e transfer of carotenoids from emulsion to mixed micelles was time and carotenoid dependent: lutein was significantly more efficiently transferred (23%) than β-carotene (9%) and lycopene (7%). A larger proportion of lycopene was transferred to the oil phase for HB particles (6%), compared to CB particles (3%); the opposite was observed for the β-carotene (29% CB and 21% HB). A very small but significant transfer of carotenoids was observed directly from tomato particles to mixed micelles: 0.09–1.6% for β-carotene and 0.05–0.09% for lycopene. Carotenoids from tomato particles were better transferred to mixed micelles from HB than from CB tomato particles. <strong>Conclusions</strong>. Carotenoids are stable during digestion but their transfer efficiency is a limiting factor for their bioaccessibility. More interestingly, we showed for the first time that processing type of tomato (HB or CB) influences the diffusion of carotenoids into emulsion and mixed micelles. Thus type of tomato processing impact carotenoid bioaccessibility and nutritional value of tomato products. Several hypotheses are under study to explain these results: modification of the structure of tomato particles and/or differences in their biochemical composition.