Hydrolyzes acetyl esters in homogalacturonan regions of pectin. In type I primary cell wall, galacturonic acid residues of pectin can be acetylated at the O-2 and O-3 positions. Decreasing the degree of acetylation of pectin gels in vitro alters their physical properties. Reduced inflorescence stem growth and increased levels of acetate in rosette leaves. Belongs to the pectinacetylesterase family.