Chemical and biological modification of cynaropicrin and grosheimin: a structure–bitterness relationship study

This work is part of a plan to investigate the structure–bitterness relationship in sesquiterpene lactones of dietary origin. The major guaianolides from artichoke (Cynara scolimus L) were chosen for this study because of their exceedingly bitter taste and well‐proven safety at concentrations currently employed in alcoholic beverages. Moreover they are available from horticultural left‐overs and amenable to a wide range of chemical modifications. We isolated cynaropicrin and grosheimin from artichoke leaves and used either chemical modification or bioconversion by basidiomycetes to prepare a number of derivatives which were submitted to a panel test for sensory evaluation. Bitterness variations appeared to be related to changes in molecule polarity. Bitter taste was markedly abated by either the loss of exomethylenes or the opening of the lactone ring.