Potential of pineapple peel in the alternative composition of culture media for biosurfactant production.

The large pineapple's consumption and processing have generated a massive amount of waste yearly, which requires adequate treatment measures to avoid damages to the environment. Pineapple peel is one of the main residues obtained from this fruit and a promising strategy to take advantage of its potential is using it for biosurfactant production due to the peel's rich composition in fermentable sugars and nutrients, such as potassium and magnesium that favor the Bacillus subtilis growth and biosurfactant excretion as well. The current research performed a central composite design (CCD) with four independent variables (glucose, pineapple peel, potassium, and magnesium), evaluating substrates' influence on the surface tension reduction rate (STRR) and the emulsification index (EI24). The results indicated that pineapple peel has the necessary potential to act as a partial substitute for glucose and salt nutrients, minimizing the costs of supplementing with exogenous minerals. The highest surface tension reduction rate (57.744%) was obtained at 2.18% glucose (w/v); 14.67% pineapple peel (v/v); 2.38 g/L KH2PO4; and 0.15 g/L MgSO4.7H2O; whereas to obtain the maximum predicted value for EI24 (61.92%) the medium was composed by 2.24% glucose (w/v); 12.63% pineapple peel (v/v); 2.53 g/L KH2PO4; and 0.29 g/L MgSO4.7H2O.