In vivo digestion of DHA-enriched egg products: Effect of the food matrix structure on the DHA digestion kinetics and bioavailability.

Over the last decades, many studies have demonstrated the beneficial effects of Docosahexaenoic acid (DHA) on human health. Nevertheless, most of these studies have been performed using DHA as a purified compound rather than as an ingredient of real and complex food matrices. However, the DHA -food matrix interaction could deeply impact on its digestibility and bioaccessibility, and hence, on its bioavailability and effectiveness. The objective of this study was to determine to what extent the food matrix structure impacts the kinetics of DHA during digestion and its final bioavailability under in vivo conditions.Three different DHA-enriched egg products with exactly the same composition but different structure (mousse, omelet and hard-boiled egg) were given to 9 pigs fitted with a T-shaped cannula at duodenal level and a jugular venous catheter. After being fed with each food matrix, blood and duodenal effluents were collected over time. DHA content in plasma and duodenal effluents was measured by GC. Additionally, total and free NH2, the degree of proteolysis and pH evolution in the duodenal samples were also determined The results concluded that the structure of the food matrix had a clear impact on both the kinetics of digestion and the final bioavailability of DHA. The mousse appeared to have been digested significantly faster than the solid omelet and hard-boiled egg. In the two latter, even 7h 30 min after the ingestion, relatively high amounts of DHA were detectable in the duodenal effluents. Proteins had a similar behavior than DHA regarding gastric emptying. The mousse, probably because of its foamy-liquid structure, allowed an easier and faster access of pancreatic and gastric enzymes, leading to a higher degree of proteolysis than the solid matrices. Finally, the bioavailability of DHA was higher after the ingestion of the omelet than for the mousse and the eggs. Acknowledgements: The authors participate in the FP7 EU Project PATHWAY-27 “Pivotal Assessment of the Effects of Bioactives on the Health and Wellbeing, from Human Genome to Food Industry” (grant agreement no. 311876)