Optimization of glucose yield from potato and sweet lime peel waste through different pre-treatment techniques along with enzyme assisted hydrolysis towards liquid biofuel

Abstract

In this work, potato and sweet lime peels otherwise considered as waste were used as substrates for producing glucose. Different pre-treatment processes were carried out and the best conditions yielding higher amount of glucose concentration were further hydrolysed by enzyme. The pre-treated extract at 80 min in case of dilute acid hydrolysis with autoclaving conditions gave higher glucose concentration amongst all the pre-treatment processes for both the peels and hence considered for further analysis. Rationale for the next step of the experiment was designed based on a central composite statistical design (CCD). To obtain high glucose yield, response surface methodology (RSM) was used to optimize the hydrolysis conditions. The three parameters chosen for the study were; time (h), temperature (oC) and the rotation frequency of the incubator (revolutions per minute i.e. RPM). The optimum conditions in case of potato peel were found to be 56 h, 68 °C and 144 RPM and in case of sweet lime peel, 56 h, 68 °C and 167 RPM. Under these conditions, 46.17 (±0.77) gL−1 and 35.90 (±0.43) gL−1 of glucose were obtained for potato and sweet lime peels respectively. The optimum factors acquired from the statistical model were further confirmed using the experimental results.