  In this work corrections to low energy punctual effective quark couplings up
to the eighth order are calculated by considering vacuum polarization effects
with the scalar quark-antiquark condensate. The departing point is a QCD-based
NJL model. By separating the quark field into two components, one that
condenses and another one for interacting quarks, the former is integrated out
with the help of usual auxiliary fields and an effective action in terms for
interacting quark fields is found. The scalar auxiliary field reduces to the
quark-antiquark condensate in the vacuum and the determinant is expanded in
powers of the quark-antiquark bilinears generating chiral invariant effective
2N-quark interactions (N=2, 3...). The corresponding coupling constants and
effective masses are estimated, and the general trend is that for increasing
the effective gluon mass the values of the effective coupling constants
decrease. All the values are in good agreement with phenomenological fits.
