The evolution of mixing torque and temperature during the manufacture of bioplastics containing oregano essential oil is illustrated in Fig. 5. In contrast to formic acid, no significant differences are noticed when the essential oil is added to the WG-based formulations. Mixing torque curves still present three different regions: (a) induction (period over which torque does not increase significantly); and (b) torque exponential increase; and (c) final decay. Thus, biocide addition just seems to slightly shorten the time interval previous to the torque exponential increase. On the other hand, 10 wt.% oregano essential oil is shown to decrease the mixing torque with respect to the reference bioplastic, although the same torque value is eventually reached. Instead, if oregano essential oil concentration is further raised up to 33 wt.% (and no glycerol is added), the resulting mixing operation presents values of torque which remain close to zero and no plasticizing process is noticed.