Study On The Taste Regularity Of Umami Peptide And The Preparation Of Flavor Condiments From Wheat Gluten

Umami peptide is a new kind tasty agent. With its rich taste, good aftertaste and synergy with other agents, umami peptide shows to be a potential market tasty agent. However, the taste regularity of umami peptides still stays unclear and the production of umami peptides relies on the experiences. The researches on the regularity of umami peptides were rare. In this paper we hydrolyzed wheat gluten by enzyme to produce umami peptides and analyzed the taste regularity of umami peptides from its relative molecular weight amino, entire and terminal acid composition and also tried to enhance umami taste by beta-cyclodextrin to lay the foundation of the researches and production of umami peptides.We studied the relationship between the umami taste of peptides and its relative molecular weight. Used centrifugation ultrafiltration to separate different wheat gluten hydrolysates and got three componentswith the Mw>3000 Da, 1000 Da<Mw<3000 Da and Mw<1000 Da. From the umami sensory evaluation, the component with Mw<1000 Da had the strongest umami taste. We controlled the peptides relative molecular weight by limiting the hydrolysis time. Results showed that with the degree of hydrolysis increased the umami got stronger.The relationship between peptide amino acid composition and umami taste was analyzed. The anion exchange resin and cation exchange resin were used to separate umami peptides. The optimal sample pH and quantity were selected by adsorption rate. As for anion exchange resin, the sample pH was 8.0, the sample quantity was 40 mg and the highest adsorption rate was 26.8%. As for cation exchange resin, the sample pH was 5.0, the sample quantity was 40 mg and the highest adsorption was 6.1%. We concluded that the umami taste was not in direct proportion to the Glu content of peptide while the basic amino acidswere important to the umami of peptides.The relationship between the umami of peptides and the terminal amino acid composition was explored. Hydrolyzed the peptides with Mw<1000 Da by Peptidase R and Accelerzyme CPG to have the terminal amino acids changed. Taking the degree of hydrolysis as criterion, the optimal Peptidase Raddition was 100 U/g and the hydrolysis time was 2 hours. The optimal Accelerzyme CPG addition was 200 U/g and the hydrolysis time was 5 hours. From the umami evalution and amino analysis, with terminal hydrophobic amino acid decreases, especially with Glu as N terminal the peptide umami increase. Synthesized 10 peptides and used electronic tongue to evaluate the umami taste and got the consistent results.We optimized composite enzymatic hydrolysis condition to produce umami flavor condiments. The reaction conditions were optimized by orthogonal experiment by taking DH and the yield of protein as criterions. The substrate concentration was 5 g/100 g water, Neutrase 1.5MG: Flavouezyme=1.5:1, total enzyme addition was 2.5 g/100 g protein, hydrolysis time was 7 hours. The resulted DH was 40.4%, the umami score was 4.9 and the umami diluted multiples was 512 which was four times as DH 13.3%.Beta-cyclodextrin was found could increase the umami taste of the wheat gluten hydrolysate. Preliminary study showedthat beta-cyclodextrin could promote the hydrolysis.The reasons may be explained by theimproved solubility of wheat gluten, the embedding of hydrolysate to promote the hydrolysis and the increase of peptides with relative molecular weight between 150 Da and 500 Da.