Modelling of the acid hydrolysis of potato (Solanum tuberosum) for fermentative purposes

The hydrolysis of non-commercial potatoes to obtain glucose solutions has a double consequence, the elimination of a waste and the generation of a value-added product. Potato hydrolysates can be used to prepare growth media for fermentative processes. This work deals with the modelling of the acid hydrolysis of potato using sulphuric acid. The effect of temperature, time, acid concentration and liquid/solid ratio were evaluated. Considering the important effect and interactions of the variable involved, a statistical Box-Behnken design was conducted including the cited variables as operational variables and concentrations of glucose, fructose, arabinose, acetic acid, furfural and 5-(hydroxymethyl)-2-furaldehyde (HMF) released as dependent variables. Significant models were obtained. The maximum glucose concentration predicted was 85 kg m−3. The conditions selected as optimal were: Temperature, 120 °C; time, 60 min; acid concentration, 2.4 kg m−3 and liquid/solid ratio, 9.8 g g−1. The acid hydrolysis of dried potatoes gave solutions with 58 kg m−3 of glucose and only 0.47 kg m−3 of HMF. These solutions are adequate for further fermentation process.