Cartoon highlighting the main molecular features of the IRAS4B1 outflow. The main emission morphology of our reference molecule, CH₃OH, is outlined in grey, including the main outflow lobes (red and blue arrows) and additional arc-like features (black lines) of currently unknown origin. The peaks of the intensity ratios with respect to CH₃OH are highlighted in teal and pink, depending on the species (see Fig. 2). A spectral line analysis was performed towards positions R1 and B1 and yielded rotational temperatures of T_rot = 60-100 K (Sect. 3.3). The position of the protostar is indicated in yellow.