Acyl-ACP thioesterase involved in the production of fatty acids and beta-keto fatty acids. Can produce beta-keto fatty acids of medium chain (8:0 and 10:0) and small amounts of 8:0 fatty acid when expressed in a heterologous organism (E.coli). May play a role in suberin biosynthesis. Expressed in endodermal and peridermal cells in young and mature roots, in boundaries of stem lateral organs and developing seeds. Belongs to the 4-hydroxybenzoyl-CoA thioesterase family.