The Effect of Plant Ontogeny on Antioxidant Capacity and Bioaccessibility of Total Phenolic Compounds and...

Broccoli sprouts are rich in some antioxidants compounds, such as: phenolic compounds and sulforaphane (SFN). However, little is known about the optimal maturation stage of sprouts to maximise these benefits and the bioaccessibility of these compounds after gastrointestinal digestion. In this study, the influence of plant ontogeny on the antioxidant capacity and bioaccessibility of total phenolic compounds (TPC) and SFN in 2-, 4- and 6-day-old broccoli sprouts was investigated. The antioxidant capacity was measured with Ferric Reducing Antioxidant Power (FRAP), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays, the TPC content with the Folin-Ciocalteu method and the SFN content with high performance liquid chromatography (HPLC). Analyses were performed on both undigested and digested samples following the in vitro digestion protocol (INFOGEST 2.0). The TPC and the antioxidant capacity measured by the ABTS method were higher in the 4-day-old sprouts, while the antioxidant capacity measured by the FRAP and DPPH methods and the SFN content by HPLC were higher in the 2-day-old sprouts. In the digested samples, both TPC and antioxidant capacity by the FRAP and ABTS methods increased as the sprouts matured. However, SFN content remained higher in 2-day-old sprouts, gradually decreasing as germination progressed. Thus, TPC bioaccessibility increased with germination time, while SFN decreased, probably due to degradation or bioconversion during gastrointestinal digestion.