The Key Techniques In Vinegar Fermentation By Immobilized Cells

Vinegar is a common family life brewing spices, which is not only rich in nutrients, but also has the unique pharmacological effects. Many functions of vinegar have been studied. Therefore, the demand for higher quality of vinegar is increased. Currently, vinegar is still produced with the traditional batch fermentation technique, and a lot of vinegar plants were closed down because of the backward technology or poor product quality. Therefore, increasing the yield and quality of vinegar and improving production efficiency can not be ignored. Vinegar brewed by immobilized cells is an effective way to change the status quo. In this paper, the optimum conditions for microorganism immobilization, the stability and storage characteristic of immobilized cells have been studied, and optimization saccharification, fermentation, acetic acid fermentation process parameters were designed with Response surface methodology. An immobilized bioreactor for vinegar was designed. The main research conclusions in this study were showed as following.The optimum conditions for microorganism immobilization with sodium alginate as the carrier was optimized, and the concentration of sodium alginate was at3%, concentration of calcium chloride at1%.The stability of immobilized particles made by sodium alginate was fine. Fermentation performance of immobilized Aspergillus niger was quite good for use of5batches (15d), and the activity was relatively stable in storage even after3months. Fermentation performance of immobilized Saccharomyces cerevisiae was also fine for use of8batches (24d), and the alcohol content was relatively stable but after40days the activity began to decline. There were no significant fluctuations in acid production by immobilized Acetobacter for use of20days. Fermentation performance declined after storage, acid production rate decreased, but the final acid volume could reach the level before storage, and the fermentation time extended.Cells of Aspergillus niger, Saccharomyces cerevisiae and Acetobacter pasteurianus were immobilized with sodium alginate as the carrier. Fermentation conditions were optimized by Response surface methodology (RSM) based on Box-Behnken experimental design. Quadratic polynomial mathematical models with good correlation were constructed and employed in the tests. The results show that the optimum conditions of saccharification were as follows: incubation temperature of34.1℃, initial pH value of6.02and volume of72.6mL the optimum conditions of alcohol fermentation were as follows: pH value of4.25, inoculum amount of9.21%and temperature of29.02℃the optimum conditions of acetic acid fermentation were as follows: inoculum amount of7.88%, initial alcohol concentration of4.63%and temperature of32℃. The experimental data and the predicted value of model were fit well.The design for bioreactor has also been studied, which can be used for expanding the experiment.