Microbial analysis of the films is presented in Fig. 3b. The films without antimicrobials (CF and CNANI) allowed the growth of yeast on its surface; therefore, these films are not suitable to act as a barrier against an external contamination of a mixed culture of S. cerevisiae and L. innocua. On the other hand, the film containing natamycin and nisin (NANI) had fungicidal effect from the first 24 h and until the end of storage. Other authors have previously reported the ability of films based on different hydrocolloids and containing natamycin for acting as a barrier to external mycotic contaminations. Olle Resa et al. (2013), studied a tapioca starch based film containing natamycin and observed that the preservative was available to prevent an external contamination of S. cerevisiae and that the antimycotic effect exerted by the films depended on the natamycin content. Also Ramos et al. (2012) studied the efficacy of films produced from whey protein isolate containing natamycin as antimicrobial agent and observed that the natamycin incorporated in the film led Y. lipolytica to depletion within 3 h of storage at 30 C.