Non-standard time reversal for particle multiplets and the spin-flavor structure of hadrons

We show that a system of quarks interacting with chiral fields provides a physical representation of a "non-standard" time reversal for particle multiplets proposed by Weinberg. As an application, we argue that, if the internal structure of hadrons is described by a chiral lagrangian, the so-called time-reversal-odd quark distribution functions might not be forbidden by time-reversal invariance.