A two stage fermentation process for production of acetic acid using star fruit juice with Saccaromycescerevisiae and Acetomonasacetii was conducted in a 2 L stirred tank bioreactor. The effect of inoculum size ( 5%,10%,15%) and agitation speed ( 250 rpm, 300 rpm, 350 rpm) on ethanol and acetic acid production of the juice were evaluated. Kinetic parameters on specific growth rate, yield, doubling time (i.e. ì,Yp/s. td,) of the fermentation process were also recorded. The optimum condition obtained from this batch fermentation was at 250 rpm of agitation speed and 5% inoculums sizes with the maximum product yield (Yethanol/glucose) of 0.859 g/g and (Y Acetic acid/Ethanol) of 0.342 g/g. The maximum specific growth rate, ì was 0.097h-1 for Saccharomyces cerevisiae while 0.085h-1 for Acetobacteraceti using initial glucose concentration of 20%. Using Central Composite Design experiment, for optimization of acetic acid production, the R2 value of 0.8372 was achieved and the highest acetic acid production obtained was 2.76 %TA while highest ethanol obtained was 17.8% or equivalent to 140.64 g/L. The above findings can be further utilized in fermentation process to produce vinegar in large amount from our tropical star fruit, Averrhoacarambola juice.
Star fruit vinegar, bioreactor, agitation speed, inoculums size
Share This Article
© The Author(s) 2014. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.