Volatile organic compounds in sugarcane silage treated with chemical and microbial additives

This study aimed to evaluate the production of volatile organic compounds in sugarcane silage treated with different additives. The treatments were sugarcane silage without additive (control) and sugarcane silage with Lactobacillus buchneri (LB), Lactobacillus plantarum and Pediococcus pentosaceus (LPPA), L. plantarum and Propionibacterium acidipropionici (LPPA), 5 g kg-L CaO (SS5CaO), 10 g kg-L CaO (SS10CaO), 5 g kg-L urea (SS5urea), and 10 g kg-Lurea (SS10urea). The contents of ethyl acetate, ethyl lactate, ethanol, and other organic acids were determined at the University of Berlin, Germany. Fifty grams of silage were weighed into glass beakers and 200 mL of distilled water and 1 mL of toluene were added to each beaker and mixed with a glass stirrer in a chemical fume hood. The beakers were immediately sealed with Parafilm and stored in a refrigerator (4°C) overnight. The next day, the solution was carefully mixed by swirling each beaker and the silage extract was obtained by filtration through a Whatman No. 54 filter paper. The extract was further filtered through a microfilter and analyzed for fermentation end products using HPLC and special GC techniques. A lower acetone concentration was verified (P = 0.001) for the treatment SS10urea, which did not differ for treatments LB, SS5CaO, SS10CaO, and SS5urea. In relation to methanol (P = 0.001), a lower concentration was also verified for the treatment SS10urea but did not differ for treatments SS, LPPP, LPPA, and SS5CaO. The propanol (P = 0.001) presented lower concentrations for the treatments SS5urea and SS10urea but did not differ for the treatments LPPP and LPPA. Butanol was only detected in the treatment SS10CaO (P = 0.001), whereas only for the treatments SS5CaO, SS10CaO, and LB was the presence of 1,2-propanediol (P = 0.001) observed, with the lowest concentration associated with LB. A lower concentration of ethanol was observed for the treatment SS5CaO and SS10CaO and a greater concentration was observed for LB, but the values did not differ among LPPA, LPPP, and SS treatments. The silages treated with CaO presented lower ethyl esters and ethanol and there was a correlation between ethyl acetate + ethyl lactate and ethanol contents. The ensilage conditions strongly affect the concentrations of acids that are produced during the fermentation process, although in the present experiment, low concentrations of these acids were obtained, thereby indicating that the ensilage was satisfactorily perform