Thermal and in vitro digestion stability of folic acid in bread

Abstract

In the literature folic acid (FA) is considered an unstable vitamin. However, it is used for food fortification even though its thermal stability has not been fully elucidated. Hence, the aim of this study was to determine the thermal stability and in vitro digestion of free folic acid. The folic acid thermal stability was determined by physical analyses (thermogravimetric and differential thermal analysis (TG-DTA)), and by the study of folic acid degradation in French-type bread produced with wheat flour fortified with folic acid. Moreover, the FA in vitro digestion from French-type bread was also investigated. The results showed that the free folic acid (FFA) degradation started at 100 °C and was completed at 155 °C/30 min or at 175 °C/5 min, while microencapsulated folic acid was entirely degraded at 100 °C/15 min. The FFA retention was of 85% in wheat flour after homogenization and of 75% in French-type bread production. The results indicated that 100% of the FA in French-type bread is free after the in vitro digestion and may be able to be absorbed by the small intestine. Thus, this study shows that French-type bread produced with fortified wheat flour can be a good vehicle for FA delivery.