Ethyl propionate (FEMA/GRAS# 2456, CAS# 105-37-3) is a distinctly poor relation. In the discrete category of aroma chemicals that display a dominant fruity rum profile, it is dwarfed in practical use by ethyl acetate. Ethyl acetate is extremely volatile, so volatile in fact that much of it is lost in a great many applications.
Ethyl propionate has a vapor pressure around a third of ethyl acetate and is consequently somewhat more heat stable. The two chemicals have very similar odors, but ethyl propionate can be used successfully at lower levels in many flavor categories. For these two reasons, its status as a poor relation is, in my opinion, more than a little misjudged.
Note that the dose rates given throughout this article are the levels suggested for use in flavors intended to be dosed at 0.05% in ready-to-drink beverages or in a simple bouillon.
For the full article, please check out Perfumer & Flavorist's September 2020 issue.