Thiesterase that shows a preference for long chain fatty acyl groups. In vitro, cleaves the thioester linkage of palmitoyl-CoA, stearoyl-CoA, lauroyl-CoA and hexanoyl-CoA (PubMed:17524985). Contains low levels of trans-enoyl hydratase activity (PubMed:19136596). a fatty acyl-CoA + H2O = a fatty acid + CoA + H(+) H2O + hexadecanoyl-CoA = CoA + H(+) + hexadecanoate H2O + octadecanoyl-CoA = CoA + H(+) + octadecanoate dodecanoyl-CoA + H2O = CoA + dodecanoate + H(+) H2O + hexanoyl-CoA = CoA + H(+) + hexanoate kcat is 0.037 sec(-1) with palmitoyl-CoA as substrate. kcat is 0.019 sec(-1) with stearoyl-CoA as substrate. kcat is 0.015 sec(-1) with lauroyl-CoA as substrate. kcat is 0.012 sec(-1) with hexanoyl-CoA as substrate. Homohexamer. Trimer of dimers. Belongs to the FcoT family.