Physicochemical and microbiological changes during tapping of palm sap to produce an alcoholic beverage called “taberna”, which is produced in the south east of Mexico

The aim of this study was to determine the physicochemical and microbiological changes that occur during “taberna” production. “Taberna” is a traditional alcoholic drink produced by natural fermentation of the sap of “coyol” palm. Samples of the fermentation from three palm trees were collected for fifteen days of tapping and these were chemically and microbiologically analysed. The main microbiota recovered in the samples were yeasts, lactic acid bacteria (LAB) and acetic acid bacteria (AAB), aerobic mesophilic bacteria (AMB) and total coliforms were also found. The initial amount of yeasts was about 3.67 log10 CFU/mL, whereas the initial bacterial population was approximately 7 log10 CFU/mL. The total counts of microorganism (yeast, LAB, AAB, AMB and total coliforms bacteria) rose in subsequent samples until the ethanol and lactic acid concentrations increased at 4.25 and 0.32% w/v, respectively, from these samples the microbial population decreased, even the total coliforms bacteria population was not detected. High-Performance Liquid Chromatographic (HPLC) was used to determine sugars, ethanol, and organic acids. Sucrose was the main sugar in the “coyol” palm sap (11.36% w/v), whereas glucose and fructose were found in low concentrations. In general, the sugar content during tapping decreased and the organic acids and ethanol content increased. The maximum ethanol concentration was 4.78% w/v and lactic acid reached 0.48% w/v in the final sample (sample 15). The pH values of the sap in the first samples were nearly neutral (7.25), however during the fermentation this value dropped due to the production of organic acids.