CalB lipase-mediated transesterification using HPA with triolein (Reaction I) or Menhaden fish oil (Reaction II). HPA, 4-hydroxyphenylacetic acid; TON, triolein; HPA-DON, HPA-diolein; FO, Menhaden fish oil; HPA-dFO, HPA-fish oil diglyceride; CalB, Candida antarctica lipase B