In vitro bioaccessibility and speciation changes of selenium in Pleurotus eryngii during the growing stage

The production of Pleurotus eryngii by selenium (Se) biofortification is an effective way to improve the demand for Se in humans. In order to investigate the Se bioaccessibility and speciation of Se-enriched P. eryngii during the growing stage, the Se distribution in biochemical fractions, and the molecular weight and the Se species of Se-containing compounds derived from in vitro simulated gastrointestinal fluids were analyzed by size exclusion and anion exchange-high performance liquid chromatography and inductively coupled plasma mass spectrometry. The results showed that albumin had the highest Se content among biochemical fractions, approximately 34.40% of total Se, followed by glutelin, globulin and gliadins. Selenomethionine that was proved to be the major Se species would increase with P. eryngii growing from 45.85% to 59.32%, while selenocysteine would decrease from 40.68% to 15.17% of total Se. In conclusion, selenocysteine would gradually convert to selenomethionine, and thus the bioaccessibility of Se was greater in mature P. eryngii than in younger mushrooms.