Reserch On Bread Yeast Extracts Of Production Technique

With high-activity and instant bread dry yeast for raw materials, processing technology ofyeast autolysis was studied.，the influences of autolysis of yeast cell were also discussed. Thefactors influencing yeast autolysis including added varieties protease, the addition quantity, yeastsuspension concentration, enzymolysis time and autolysis time were investigated with aminonitrogen gain rates as main indicators. Rised the dehydration of high-activity bread dry yeast,through3degradation methods including yeast autolysis, hydrolysis by papain, hydrolysis byneutral proteinase and hydrolysis by high-pressure homogeneity. The main results are asfollows：1. Used sucrose-solution for dry yeast activity medium, through the comparison of theeffects of different dehydration temperature, sucrose solution concentration, solid-liquid ratioand time on yeast activity. Contrasted the different the dehydration and activation of yeast byorthogonal experiment, conditions of yeast activity were optimized, the results show that: thebest dehydration temperature was at35℃, sucrose solution concentration was4%,solid-liquid ratio was1:15, and the activation time was1h. The dehydration and activation ofhigh-activity bread dry yeast could directly influence yeast activity and yeast autolysis.2. Processing technology of yeast autolysis was studied.，the influences of autolysis ofyeast cell were also discussed. Orthogonal experiments showed that45℃，pH=6.5, the ratioof baker’s yeast water was1:10and addition of2%NaCl and0.5%alcohol for36h autolysiswas the best optimizing autolytic environment. Then obtained4.16%amino nitrogen forbaker’s yeast cell (dry basis), which owns strong palatable taste and flavour enhancement.3.Studied on the effect of yeast autolysis and product flavor of6kinds of enzyme(β-glucanase, papain, neutral proteinase A, neutral proteinase B, alkaline protease A, alkalineprotease B) and the compound enzymolysis (β-glucanase-alkaline protease) on yeast autolysis.Optimization of every kind of enzymolysis process showed that various proteinases could rise2.5%~20%amino nitrogen on yeast autolysis, and produce different of aroma or tastecharacteristics of yeast extract. And the best choice was the compound enzymolysis(β-glucanase-alkaline protease), the yield of amino acid reached5.5%.4. After dealing with high-pressure homogeneity under the optimum condition, therates of amino nitrogen of yeast extract rose to5.45%，which owns strong palatable taste andflavour enhancement. The results show that, under the40Mpa, had twice high pressurehomogenization before autolysis of yeast extract, could rise amino acid nitrogen to4.80%,improve by15%.5. Considering the many factors of yeast extract, such as quality, economy, productionand operation, have some suggestions as follow:(1) the production of the general quality of yeast extract could make capital of autolysis process, with adding NaCl and ethanol;(2)Dealed with high-pressure homogeneity before autolysis processing, can effectively improvethe quality of yeast extract, which would be more suitable for mass production. But during theprocess, manufacturers should control the homogenizing process strictly, for avoiding thepollution source;(3) For producting sme kinds of high-end or some special requirementproducts, we could cho0se the way of enzyme hydrolysis of yeast.