Purpose: The aim of this study was to assess the prevalence and diversity of yeasts isolated from FCOJ collected from an industry as well as to assess the resistance profile of the isolates against peracetic acid.
Methods: A total of 1,500 samples of FCOJ were collected between March - July, 2014, from an industry located in the state of Sao Paulo, Brazil. The juices were plated onto Wort Agar (WA), and plates were further incubated at 25°C for 5 days. The isolates were recovered and further subjected to identification through sequencing of D1/D2 major subunity of RNAr. The resistance of isolates to peracetic acid (0, 50, 80, 100, 150 and 200 ppm) was assessed through a microplate method with an exposure time of 3 min, initial level of yeasts of 102-3 CFU/ml, and further plating onto WA, following incubation at 25°C/120 h.
Results: Yeasts were recovered from 17% of FCOJ samples, totaling 280 isolates. Until now, a total of 98 isolates have been identified, belonging to nine different genus, Candida spp., Kluyveromyces spp., Saccharomyces spp., Toluraspora spp., and Zygosaccharomyces spp., being the 5 major genera found. A total of 21 different species have also been identified. From the identified isolates, 36.7% (n = 36) were resistant to up to 200 ppm of peracetic acid.
Significance: Although the prevalence of yeasts in FCOJ could be considered low, the diversity of isolates and their high resistance to peracetic acid, potentially pose a challenge for their elimination of FCOJ processing environment.