FERREIRA, J. M.; http://lattes.cnpq.br/1966216398901568; FERREIRA, Joelma Morais.
Abstract:
The acetic fermentation is an oxidation process accomplished by a group of
bacterias of the gender Acetobacter. The acetic acid produced by bacterias of this
gender is the main compound of the vinegar. The production of a good vinegar
depends on a series of factors as concentration of alcohol, temperature, oxygenation,
pH and nutritious. This work had objective to study on bench scale, the optimum
conditions of acetic acid fermentation, a process very much used in small industries of
the state of Paraiba in the production of the vinegar. Initially a kinetic study of the
acetic fermentation was performed with the intention of determining the influence of the
variables: ethanol concentration, phosphorous concentration and concentration of
nitrogen on the process in different intervals of time. For this a study with
concentrations of ethanol of 2%, 4%, 6% and 8%, of phosphorous 0,05g/ml and
0,2g/ml, and of nitrogen of 0,5g/ml and 2,0g/ml, was made. Through the kinetics, it was
not possible to observe conclusively the influence of the variables of the process
studied. The methodology of complete factorial 23 planning was used, where the
entrance variables were initial concentrations of ethanol, phosphorous and nitrogen.
Tests were, accomplished with concentrations of ethanol 3%, 6% and 9%, in volume,
concentrations of phosphorus 0,01 g/ml, 0,03g/ml and 0,05g/ml and concentrations of
nitrogen 0,1 g/ml,0,3g/ml and 0,5g/ml. After the analyses it was necessary to elaborate
another planning, enlarging the range of the variables. This time the planning was of
the type 22 plus star configuration. Through the empirical mathematical models
obtained and analysis of surface response it was verified that the controlled variable
that presented great influence on the yield and productivity of the process was initial
concentration of ethanol which has an optimum value of 4%. The nitrogen presented a
discreet influence at the concentration of 1,7g/ml while the phosphorus didn't show any
perceptible influence. It was also possible to observe, through the data of the variance
analysis, that the empirical model observed is statistically significant.