Modelling gas–liquid and liquid–gas transfers in vinegar production by genetic algorithms

Abstract

The transfer of oxygen from aeration flow to the fermentation medium and the transfers of ethanol, ethyl acetate, acetoin, acetic acid and water from the fermentation medium to aeration flow were modelled for the industrial production of vinegar. The study was developed in a pilot fermentor, working with continuous processes and industrial fermentation mediums. The cores of the proposed models were the semi-empiric correlations for the volumetric transfer coefficients k L a for oxygen transfer and k A,G a for the liquid–gas transfers. The main novelty was the introduction of the effect of pressure on the fermentation medium, together with the expression proposed for k A,G a, with the same structure as the expression for k L a. A genetic algorithm was developed to calculate the parameters of the models, with a four composed desirability function as the evaluation function. The optimised sets of parameters provided models with good predictive ability. The models can be applied for any fermentor with the same agitation and aeration system design and the same geometry.