Plant-based beverages supplemented with Se-microparticles: a comprehensive study of absorption and gastrointestinal simulation using static and dynamic in vitro digestion models

Abstract

This study evaluated and compared the physicochemical properties, antioxidant capacity, and Selenium (Se) bioaccessibility and intestinal absorption (bioavailability estimate) of almond, rice, and soy beverages fortified with microencapsulated organic (Selenium-L-cystine) or inorganic (sodium selenate) Se. These were compared against a traditional homemade Brazil nut beverage, naturally rich in this mineral. Supplementation produced matrix-dependent effects, notably slight reductions in L* (lightness) and consistent increases in b* (yellowness). After in vitro digestion, antioxidant activity and total polyphenol content increased, indicating digestion-driven release of bioactive compounds. Se bioaccessibility, assessed via static and dynamic models, varied significantly by food matrix. In the static digestion approach, almond beverages showed high soluble fractions (84–93%), rice lower values (63–70%), soy intermediate levels (67–79%), and Brazil nut beverage reached approximately 97%. In the dynamic system, bioaccessibility was generally higher for all drinks (almonds 89–93%; rice 70–81%; soy 61–97%), with Brazil nut exceeding 100%. Caco-2 assays, used to estimate the intestinal absorption component of Se bioavailability through transepithelial transport cells, indicated the highest Se absorption in rice beverages (~9–10%), while Brazil nut beverage, despite its high Se content, showed the lowest absorption rate (~2%). Findings highlight the dominant influence of matrix composition over Se chemical form on Se bioaccessibility and intestinal absorption, supporting the importance of considering both food matrix and Se species when designing fortified plan-based beverages.