In vitro assessment of potential intestinal absorption of some phenolic families and carboxylic acids from commercial instant coffee samples

Abstract

Coffee is one of the most consumed beverages in the world, being a source of bioactive compunds as well as flavors. Hydroxycinnamic acids, flavonols, and carboxylic acids have been studied in samples of instant coffee commercialized in Spain, The studies about contents of food components should be complemented with either in vitro or in vivo bioaccessibility studies to know the amount of food components effectively available for functions in the human body. In this sense, a widely used in vitro model has been applied to assess the potential intestinal absorption of phenolic compounds and organic acids. Contents of hydroxycinnamic acids and flavonols were higher in instant regular coffee samples than in decaffeinated ones. Bioaccesible phenolic compounds in most analyzed samples account to 20-25 % of hydroxycinnamic acids and 17-26 % of flavonols. This could mean that a great part of them can remain in the gut, acting as potential in situ antioxidants. Quinic, acetic, pyroglutamic, citric and fumaric acids were identified in commercial instant coffee samples. Succininc acid was found in the coffee blend containing chicory. All carboxylic acids showed a very high bioaccesibility. Particularly, acetic acid and quinic acid were found in higher contents in the samples treated with the in vitro simulation of gastrointestinal process, compared to the original ones, which can be explained by their cleavage from chlorogenic acid during digestion. This is considered as a positive effect, since quinic acid is considered as an antioxidant inducer.