Casimir Invariants from Quasi-Hopf (Super)algebras
  We show how to construct, starting from a quasi-Hopf (super)algebra, central elements or Casimir invariants. We show that these central elements are invariant under quasi-Hopf twistings. As a consequence, the elliptic quantum (super)groups, which arise from twisting the normal quantum (super)groups, have the same Casimir invariants as the corresponding quantum (super)groups. 
Mark. D. Gould, Yao-Zhong Zhang and Phillip S. Isaac