Bound phenolics release from dried bamboo shoots prepared by different processes during in vitro gastrointestinal digestion: bioaccessibility and bioactivity

In this work, the release pattern of bound phenolics in salt-dried bamboo shoots (SDBS), steamed dried bamboo shoots (TDBS), fumigation dried bamboo shoots (UDBS) and fermentation dried bamboo shoots (FDBS) during simulated in vitro digestion was studied. The result exhibited that polyphenols in dried bamboo shoots (DBS) mainly existed in the form of bound phenolics, amongst them the content of FDBS was the highest, followed by SDBS and TDBS, and UDBS was the lowest. In addition, release amounts of bound phenolics in SDBS, TDBS, UDBS and FDBS after gastrointestinal digestion were significantly higher than that after gastric digestion, accounting for 19.61%, 19.40%, 45.64% and 19.66% of the total, respectively. Moreover, IC50 values for scavenging ability of DPPH and ABTS radicals by gastric and gastrointestinal digestion supernatant for DBS were in a descending order: FDBS, UDBS, SDBS and TDBS. Rutin, p-coumaric and ferulic acid were discovered to be the predominant compounds in digestion supernatant. Trustworthy, fluorescence microscope pictures of DBS at different digestion stages further confirmed the release regularity of bound phenolics. Therefore, these findings could provide a theoretical support for the optimal processing of DBS.