Yeast Extract Preparation from Waste Beer Yeast by Autolysis Coupled with Enzymes Addition & Its Physiochemical Properties Testing

In order to make full use of waste beer yeast, the technique of autolysis coupled with enzyme addition was employed to produce yeast extract. The factors influencing yeast autolysis including added protease varieties, the addition quantity, yeast suspension concentration, autolysis time and enzymolysis time were investigated with solids grain rates and amino nitrogen gain rates as main indicators. Besides, the accelerants related to yeast autolysis were selected by orthogonal experiments. The parameters of evaporation and spray desiccation had been determined. Furthermore, the physiochemical properties of yeast extract including metal ions content, solubility, pH value and total amino acids content were measured. The amino nitrogen gain rate and solids gain rate of the produced yeast extract reached at 3.937 % and 59.24 % respectively. Most of its physiochemical indexes could meet or exceed the Quality Indexes Requirements in Yeast Extract Industry.