DETERMINATION OF LACTIC ACID PRODUCTION BY RHIZOPUS ORYZAE IN SOLID STATE FERMENTATION OF PINEAPPLE WASTE

Abstract

Solid pineapple waste (SPW) is one of the most abundant agricultural wastes found in tropic region. This study is looking into the potential of utilising solid pineapple waste in solid state fermentation for the production of lactic acid by Rhizopus oryzae. A 2-level factorial design was employed to screen the effect of moisture content (60% and 80%), inoculum size (1×104 spores/g and 1×108 spores/g), pH (4.5 and 6.5), temperature (27°C and 40°C) and particle size (<0.5 mm and >3.15 mm) to the production of lactic acid. The predicted maximum production is 0.0221 g lactic acid/g SPW in SSF condition of 80% moisture; pH 6.5; 1×104 spores/g of inoculum; waste particle of 3.15 mm; and temperature 27°C. Analysis of variance (ANOVA) showed that the model is significant with high value of predicted (0.9616) and adjusted (0.9726) R-squared, indicated a good agreement between the predicted and actual values at each point of the experiment. Post-statistical experiment confirmed the ability of lactic acid production by R. oryzae at the predicted conditions with 0.0236 g lactic acid/g SPW being produced.