Abstract
Effects of various neutralization agents on the lactic acid production from cassava with medium fermentation of trypto-soya by Streptococcus bovis were investigated. A batch fermentation unit with a single stirred fermenter was used for the lactic acid production. The broth fermentation was buffered by three different agents, i.e.: CaCO3, NaOH, and NH4OH. Fermentation experiments were performed at 37°C either with initial adjustment or periodical adjustment, using cassava, tapioca and glucose as substrates. For initial adjustment fermentation, neutralization agent of CaCO3 was used, while for periodical adjustment fermentation agents of NaOH and NH4OH were used to maintain at pH 5.00 ± 0.2. The results showed that buffer agent of CaCO3 can be applied successfully to produce lactic acid. The maximum lactic acid concentrations were 25.7 g l-1, 22.4 g l-1 and 22.3 g l-1 with buffer agents of CaCO3, NaOH and NH4OH respectively at substrate concentration of 30 g l-1. While the maximum productivity was 0.48 g l-1h-1, 0.50 g l-1h-1 and 0.52 g l-1h-1 with buffer agents of CaCO3, NaOH and NH4OH respectively.
