The Preparation Of Yeast Extracts Based On The Maillard Reaction

In this thesis, effects of several method on yeast cell wall broken with total amount of amino acids nitrogen in supernatant,in which the Saccharomyces cerevisiae was used as material,and the technology conditions of yeast cell wall broken was optimized;Then the enzymatic process were studied and optimized on supernatant,the physical and chemical properties of yeast extract were also detected.;Then the maillard reaction process was used to improve flavoring of yeast extract.1. The method selected and technology conditions optimizated of yeast cell wall brokenThe best method of yeast cell wall broken was determined through the research on ultrasonic wave,enzyme,autolysis and high pressure homogenization,in which,the Saccharomyces cerevisiae was used as material.The optimum technology conditions was identified by the orthogonal experiment as follows:the temperature was 50℃,autolysis time was 26 h,and pH 5.0.Based on this condition, amino nitrogen content was 0.114 g/100 mL,about 2.27% of the dry yeast.2. Enzymatic process of yeast supernatantBecause of the limited vitality of Endogenous enzymes and declined as the autolysis process,in order to improve the yield of yeast extract and amino nitrogen, effects of Protamex,Trypsin,Papain, β-glucanases and flavourzyme on enzymatic was compared. The results showed that Trypsin was the best enzyme on the basis of amino nitrogen content.Then,optimized the enzymatic conditions through response surface design method to be:enzymatic temperature was 50.8℃,time 4.42hand pH 6.38.Under this condion, amino nitrogen content was 0.172 g/100 mL,about 3.47% of the dry yeast.3. Physical and chemical properties detect of yeast extractAccording to the physical and chemical properties detect of the main ingredient in yeast extract,the result shows that there were 10.3% sodium flavor nucleotides,28.8% free amino acids and various vitamins. In addition,Abundant amino acid content can also be the raw materials for Maillard reaction.4. Research on enriched the flovor of yeast extract by maillard reaction processYeast extract and amino acid from it were used as the maillard reaction raw materials,depend on the response surface design method to optimize the maillard reaction conditions. The optimized conditions of maillard reaction were founded out to be:time 31.30 min, temperature 50.8℃,and pH 7.06. Under this condition,the fragrance, color and browning of the product were the best after Maillard reaction.