Lactococcus species are used for production of Coalho cheese, a semi-hard, medium-to high-moisture (low-ripened) cheese typical of the northeast region of Brazil ( Queiroga et al., 2013). This cheese possesses good acceptance among consumers (Garcia et al., 2012) and is produced through simple technology following milk coagulation using rennet or proper coagulating enzymes, which are commonly complemented with selected starter culture mainly composed of L. lactis subsp. lactis and L. lactis subsp. cremoris ( Brazil, 1997), and must be consumed in a maximum period of 21 days under cold storage ( Garcia et al., 2012 and Oliveira et al., 2012). Considering these aspects, in the present study, we assessed the effects of TVEO toward the pathogenic bacteria S. aureus and L. monocytogenes and a mesophilic starter co-culture comprising L. lactis subsp. lactis and L. lactis subsp. cremoris. These effects were measured (and compared) through the determination of the minimum inhibitory concentration and the assessment of the bacterial cell viability over time in a (coalho) cheese-based broth and a semi-solid (coalho) cheese model.