*2.1.2 Research design*

The research design is experimental with a 3 x 2 x 2 factorial arrangement with experimental tests carried out with two repetitions. The temperature was considered with three levels: 24 C, 28 C, and 32 C, the pH with two levels: 3.5 and 4.5; and the nutrient concentration with two levels: 1 g/L and 2 g/L. The response variable was the ethanol concentration.

**Table 2** shows the experimental design of the first stage of the alcoholic fermentation process of blue cabuya juice at different conditions: temperature, pH, and DAP nutrient concentration, for a substrate concentration of 60 g/L [20].
