f_D1 and f_D2 ratios toward the isolated protostar sink M048-I for varying temperatures during the prestellar phase. The tracer particles are binned according to the time at which they reach the hot corino, in bins with a width of 50 kyr. The time corresponds to the time after the onset of collapse, t₀. Each bar shows the median values of tracer particles accreted in the time interval, and the error shows the [15.9, 84.1] percentiles.