Effects of neutralizing agents on lactic acid production by Rhizopus oryzae using sweet potato starch

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Title:	Effects of neutralizing agents on lactic acid production by Rhizopus oryzae using sweet potato starch
Authors:	Yen, H.-W.a , Chen, T.-J.a, Pan, W.-C.b, Wu, H.-J.b
Contributors:	Department of Chemical and Materials Engineering, Tunghai University
Keywords:	Calcium carbonate;Neutralizing;Rhizopus oryzae;Starch
Date:	2010
Issue Date:	2013-05-21T09:13:06Z (UTC)
Abstract:	A neutralizing agent is usually employed to counteract the pH reduction during lactic acid fermentation by Rhizopus oryzae. Calcium carbonate (CaCO 3) is used as such a pH controlling agent. The low solubility of CaCO 3 in the fermentation broth could however lead to low efficiency in pH control and cause problems in the subsequent purification process. Therefore, an alternative agent in place of CaCO 3 was examined in this study. The effect of four different neutralizing agents, including CaCO 3, sodium hydroxide (NaOH), ammoniacal solution and sodium bicarbonate (NaHCO 3) on lactic acid production and the morphology of the pellets were investigated. Results indicated that CaCO 3 was still the preferred choice, because of the pellet morphology and the highest lactic acid concentration (43. 3 g/L) obtained in the batch using 60 g/L of sweet potato starch as feedstock. It is noteworthy that the lactic acid purification is relatively easier when using NaHCO 3 instead of CaCO 3, due to the higher solubility of sodium lactate than calcium lactate. Therefore, even the batch with CaCO 3 had a slightly higher productivity (1. 23 g/L/h) than the batch with NaHCO 3 (1. 14 g/L/h), NaHCO 3 might be the first choice for process designers whenever recovery is vital. ? Springer Science+Business Media B.V. 2009.
Relation:	World Journal of Microbiology and Biotechnology Volume 26, Issue 3, March 2010, Pages 437-441
Appears in Collections:	[Department of Chemical and Materials Engineering ] Periodical Articles

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