Distribution and in vitro availability of selenium in selenium-containing storage protein from selenium-enriched rice utilizing optimized extraction.

Selenium (Se) distribution in Se-enriched rice and optimization of extraction for Se-containing protein were studied. Se availability in Se-containing protein product was simulated using an in vitro gastrointestinal digestion. The results showed that Se was predominately found as organic Se, whereas inorganic Se comprised only 2.85% of the total Se. The glutelin fraction contained the largest amount of Se, approximately 31.3% of the total Se in the rice gain. Utilizing orthogonal analysis, the optimum extraction conditions were selected at a volume to weight of 20:1, 0.08 M NaOH, an extraction time of 3 h, and at a temperature of 35 degrees C. A Se-containing rice protein product with 83.5% protein and 9.09 microg g(-1) Se was sequestered using the optimal extraction method. This rice protein product with high molecular weight Se-containing protein can readily be digested to low molecular weight peptides and selenomethionine (52.3% of total Se in protein extract).