Adult and older adult in vitro dynamic digestions of α-tocopherol fortified yogurt using DIDGI®

International audience

English. Age-related losses of physiological functions in older adults are of utmost importance since they directly impact their metabolism, decreasing their ability to digest and adsorb food nutrients. Fortified and functional foods have been regarded as novel alternatives to improve nutraceuticals and bioactive compounds’ delivery extent, increasing foods nutritional properties. the development of tailored foods for older adults aims at providing compounds that are expected to decrease the risk of diet-related diseases., it is critical to understand how these food products interact with other food components, what is their behavior in the gastrointestinal tract and if the formulation modulated, in fact, their bioaccessibility and bioavailability. In vitro gastrointestinal models have become very relevant to evaluate food behavior and must be adapted to the physiological stage targeted. The objectives of this work wera to simulate the digestive conditions of the older adults as mentioned in Menard et al; 2023 by the INFOGEST network using the dynamic system (DIDGI®) and to evaluate the influence of the digestive conditions (adult vs older adult) in the digestibility and on the kinetic release of α-tocopherol from fortified yogurts. Natural fat and sugar free stirred yogurts were supplemented with oil-in-water nanoemulsions containing 15 mg of α-tocopherol. For the adult, the dynamic in vitro digestive parameters were used as described in Menard et al 2018 on yogurt digestions, and for the older adult, parameters were fixed in order to simulate a longer gastric emptying time, a slower gastric acidification profile and a reduction of 30 to 40% of enzymatic level as compared to the adult. During the gastric phase, particle size profiles were measured and in the intestinal phase, the α-tocopherol, either total or soluble, to simulate the bioaccessibility, was analyzed to monitor release kinetics.Despite the lower enzymatic activity and slower acidification profile applied in the gastric phase of the older adult, particle size distribution analysis demonstrated that the initial degradation of the fortified yogurt was similar at earlier stages of digestion, due to longer gastric half-life. Conversely, at the end of the gastric phase, the adult protocol was substantially more effective in degrading and homogenizing the gastric content. The α-tocopherol kinetics reached during the intestinal phase were more important at the adult stage. with 97.3 ± 5.9 % of recovery whereas for the older adult 79.8 ± 5.2 % was obtained. Bioaccessibility was identical in both stages (ranged from 60 to 80 %), being statistically significantly higher at 3 hours in the older adult.Globally, α-tocopherol release kinetics were greatly affected by the physiological stage thus leading to relevant differences in its release extent and profile.