Cacao pod husk for citric acid production under solid state fermentation using response surface method

Indonesia is one of the biggest cocoa producers in the world with total production 240,000 tons by 2019. Meanwhile, we have about 400,000 tons cocoa pod husk (CPH). CPH biomass is a serious problem in Indonesia, but at the same time, it is also an important, challenging, and environmental renewable source for bioproduction. Therefore, it becomes a focus of interest in this research aiming to utilize of CPH as renewable substrate for citric acid production. The solid-state fermentation (SSF) approach was applied to CPH using Aspergillus niger Tiegh F359 for produce citric acid. Response surface methodology (RSM) was used to optimize the citric acid production with water concentration, nitrogen concentration, and fermentation time as variable factors. Around 7530 ppm citric acid was produced from 1 g CPH as a carbon source. Entirely, this study has succeeded in optimizing citric acid production by using SSF using A. niger Tiegh F359 and providing a fundamental study for CPH as low-cost renewable substrate for bioproduct production and future endeavors.