In short, different ECFPs won't statistically affect the performance of our bitterant/non-bitterant classification in the context of the same machine-learning method with the full features. From this view, the default choice of 1024bit-ECFP4 or 2048bit-ECFP6 is generally acceptable in the bitterant/non-bitterant classification. In our case, four ECFPs are still adopted, since their combination with the feature selection, multiple machine-learning methods and consensus strategy may offer a better solution, which will be discussed as follows.