USE OF TWO NATURAL ANTIMICROBIAL ADDITIVES IN THE SOLID FERMENTATION OF APPLE BAGASSE

Abstract

The antimicrobial effect of oregano essential oil and zeolite on solid-state fermentation (FES) of apple bagasse was evaluated. Zeolite 5% clinoptilolite (ZEO), 0.1% oregano essential oil (AEO) and both (ZXA) were used, against the traditional method of molasses broth added with urea, ammonium sulfate and minerals as control (CTL). Three repetitions per treatment were performed in 1 L tanks, with sampling at 0, 6, 12, 24, 48, 72 and 96 h. The variables evaluated were plate microbial count, pH and yeast count with a Neubauer chamber. The data were analyzed with a model of repeated means over time and comparison of multiple means. Maximum yeast growth was obtained at 48 h in ZXA (462 x106 cel/g), while in CTL at 96 h (470.5 x106 cel/g), reducing fermentation time and optimizing the process. The aerobic bacteria count was decreased (P <0.01) at hour 48, from 0.70 x106 CFU/g in CTL to 0.25 x106 CFU/g in ZXA, with AEO having the lowest bacterial count (0.11 x106 CFU/g). pH was higher (P <0.01) in ZEO (4.80) and ZXA (4.62), against CTL (4.06) and AEO (4.03). It is concluded that the use of both additives provides microbiological advantages over the traditional FES process, which reduces the fermentation time and avoids bacterial contamination, guaranteeing a process free of microbiological contaminants.