Rahmayetty, Rahmayetty and Yulvianti, Meri and Hartono, Rudi (2022) Artikel_Synthesis of Lactic Acid from Molasses by Lactobacillus acidophilus Using a Batch Fermentation Process. Jurnal Rekayasa Kimia dan Lingkungan, 17 (2). pp. 104-113. ISSN 1412-5064

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Abstract

Lactic acid is a chemical with widespread applications, mainly in pharmaceutical, cosmetic, chemical as well as food industries. One of the major uses of lactic acid is the precursor of polylactic acid (PLA). PLA is biodegradable and biocompatible material that can be an alternative to conventional plastic derived from fossil fuels. Efforts continue to be made to reduce the high cost of producing PLA in order to compete with conventional petrochemical-based plastics. One of which is the use of molasses as a raw material because it is cheap and contains high quantity of glucose. This study aims to obtain the value of the cell concentrations with various addition of starter volume, that produces high concentrations of lactic acid, and to obtain the growth kinetics of Lactobacillus acidophilus during the fermentation process. This study was conducted in several stages, i.e., the design of bioreactors, inoculation of Lactobacillus acidophilus, and fermentation of molasses. In a batch system, molasses substrate was directly inserted as much as 500 ml into the bioreactor and various amount of starter of Lactobacillus acidophilus (1; 3; 5 dan 10% v/v) were added to the fermentation medium. The fermentation of molasses observed for 72 hours and the product was analysed every 8 hours. The highest concentration of lactic acid produced in batch fermented molasses, 23.1 mg/L, resulted from the addition of 5% (v/v) starter bacteria, that last for 72 hours fermentation time. The value of the carrying�capacity coefficient (k) and the maximum net specific growth rate (µnet) were 0.2379 h-1 and 0.0160 h-1 respectively.

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