Citric Acid Production Optimation from Toba Banana Peel Through Submerged Fermentation by Aspergillus niger Using Central Composite Design

Abstract

Toba Banana (Musa acuminata Colla) is a local banana in Toba region, North Sumatera, Indonesia. People only utilize its pulp fruit, then its peels can cause environmental problems. Carbohydrate in banana peel can be utilized as substrate to produce citric acid through fermentation. Citric acid is an organic compound that is widely used in several industries. This research aims to find the optimum condition of Toba banana peel as substrate to produce citric acid through submerged fermentation by Aspergillus niger. Parameters observed were substrate concentration 15-30% v/v, sucrose concentration 0-5% w/v, methanol concentration 0-4% v/v, and working volume 100-1000 mL. Sampling was conducted every 24 h during 5 days fermentation to measure its pH and citric acid concentration. The highest citric acid concentration was achieved on day 3 of the fermentation with concentration 15.31 g/L in pH condition 2.12, banana peel concentration of 222.3 g/L (22.23% w/v), sucrose concentration of 26.3 g/L (2.63% w/v), methanol concentration of 21.4 mL/L (2.14% v/v), and working volume 1000 mL. From this result, it can be concluded that Toba banana peel is a potential substrate for producing citric acid by Aspergillus niger through submerged fermentation in those optimum conditions.