Plain language summary
Selenium (Se) is a soil-based trace element essential for immune system functionality, hormone regulation and muscular metabolism, however several regions in the world are deficient in Se. The current approach to this global health issue is fortification with Se-enriched flour, but this comes with its trials due to a small range between deficiency and toxicity. The primary aim of this study was to identify whether sourdough fermentation increases the bioavailability of Se in a typical flatbread. Flatbreads were prepared with either control wheat flour or inorganic Se-enriched wheat flour, and both were subject to conventional and sourdough fermentation. The variations were submitted to in vitro simulation human digestion and the biological effect of products were tested using cultured liver cells. This study found the use of Se-enriched flour significantly increased Se content of the flatbread. Sourdough fermentation, compared with conventional fermentation, led to a major conversion of inorganic Se present in the flour into the organic species, which is significantly more available for absorption. Based on these results, the authors conclude sourdough fermentation is a strategy that should be utilised to improve Se deficiency throughout the world.
Abstract
Although selenium is of great importance for the human body, in several world regions the intake of this essential trace element does not meet the dietary reference values. To achieve optimal intake, fortification of bread by using selenium-enriched flour has been put forward. Less is known on the potential effect of sourdough fermentation, which might be worth exploring as the biological effects of selenium strongly depend on its chemical form and sourdough fermentation is known to cause transformations of nutrients and phytochemicals, including the conversion of inorganic selenium into organic selenocompounds. Here we investigated the bio transformation of selenium by sourdough fermentation in a typical Italian flatbread (piadina) made with standard (control) or selenium-enriched flour. The different piadina were submitted to in vitro digestion, and the biological activity of the resulting hydrolysates was tested by means of cultured human liver cells exposed to an exogenous oxidative stress. The use of selenium-enriched flour and sourdough fermentation increased the total content of bioaccessible selenium in organic form, compared to conventional fermentation, and led to protective effects counteracting oxidative damage in cultured cells. The present study suggests that selenium-rich, sourdough-fermented bakery products show promise for improving human selenium nutrition whenever necessary.
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