There are three typical studies about the general bitterant prediction with the machine-learning approach based on the relatively large dataset (Rodgers et al., 2006; Huang et al., 2016; Dagan-Wiener et al., 2017), although there are several studies about the congeneric systems with the comparatively small dataset (Takahashi et al., 1982; Spillane et al., 2002; Cravotto et al., 2005; Scotti et al., 2007). In addition, all these studies focus on the prediction of small-molecule bitterant, which is our current main research interest, thus the prediction of bitter peptide explored in the other studies (Ney, 1979; Soltani et al., 2013) will not be reviewed here.