  We present a new perturbative approach to QCD based on the use of quark
composites with hadronic quantum numbers as fundamental variables. We apply it
to the case of the nucleons by performing a nonlinear change of variables in
the Berezin integral which defines the partition function of QCD. The nucleon
composites are thereby assumed as new integration variables. We evaluate the
jacobian and certain transformation functions which appear in the change of
variables. We show that the free action of the nucleon composites is the Dirac
action, and we evaluate the first perturbative contributions to their
electroweak effective action, which turn out to be a pure renormalization. Our
expansion is compatible with a perturbative as well as nonperturbative regime
of the gluons and it has the characteristic feature that the confinement of the
quarks is buit in.
