ABSTRACT
This experiment was performed with the aim of optimizing oxalic acid production from ternary feedstock mixture of pineapple pomace, banana peel and orange pomace using Sclerotinia sclerotiorum. Banana peels, pineapple pomace, and orange pomace were collected, washed, dried, and ground to a uniform particle size. The fungus Sclerotinia sclerotiorum was used as the fermenting organism. Fresh cultures were used to prepare a spore suspension with a concentration of 2 x 107 spores/mL. The dried and ground substrate mixtures (15 g total) were sterilized, wetted with a nutrient medium, inoculated with the spore suspension, and incubated for 7 days. After incubation, the fermented substrates were mixed with water, agitated, and filtered. A colorimetric method using sulfuric acid, potassium dichromate, and rhodamine B was used to measure the amount of oxalic acid produced, using absorbance values with reference to oxalic acid standard calibration curve. The optimal substrate mixture contained 2.376 g of pineapple pomace, 9.671 g of banana peels, and 2.953 g of orange pomace. This ternary mixture resulted in an Oxalic Acid yield of 31.6968 g/L and a desirability value of 0.977. A box Behnken design was created with varying amounts of inducers (methanol, ethanol and isopropanol). The optimum yield by the box Behnken design was 0g of methanol, 0g of ethanol and 0g of isopropanol, with oxalic acid yield of 9.906781 g/L and a desirability value of 0.845903.
