Isolation and Characterization of Acidic Peptides in Soy Sauce

Abstract

A soy sauce sample was fractionated by gel filtration on a Sephadex G-15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A-25 column. The acidic subfractions with various acidities were further fractionated, using a preparative amino acid analyzer and by paper chromatography to separate the acidic peptide components.Four dipeptides and sugar derivatives of ten dipeptides and two tripeptides were isolated and characterized as the major acidic peptides in soy sauce. However, it was difficult to anticipate any direct contribution of these pep tides to the flavor construction in soy sauce on the basis of their contents and taste intensities.In the preceding work,I1 a soy sauce sample was fractionated by gel filtration on a Sephadex G-15 column, then the fractions were subfractionated on the basis of acidity by ion exchange chromatography on a QAE-Sephadex A-25 column. After the preliminary fractionation, the components in the neutral subfractions were converted to copper salts and chromatographed on a DEAE-Sephadex column to separate peptide substances from a large amount of free amino acids. The peptide fractions were further fractionated on a preparative amino acid analyzer and by paper chromatography to separate the peptide substances. Thus, three glycodipeptides and eight dipeptides were isolated and characterized as the major neutral peptide components in soy sauce. However, the practical contributions of these components to the flavor construction in soy sauce were evaluated as negligibly small.The present work deals with the peptide substances in the acidic subfractions obtained by the preliminary fractionation. Major acidic peptide components were isolated from the acidic subfractions and characterized, and their t

Gene Cloning, Purification, and Characterization of a Novel Peptidoglutaminase-Asparaginase from Aspergillus sojae

“…Therefore, since the concentration of glutamate in soy sauce moromi is positively correlated with the cell wall-bound glutaminase activity of Aspergillus species (23), this glutaminase may be involved in glutamate production during the fermentation of soy sauce. Furthermore, several short acidic peptides containing L-Glu or L-Asp residues at the C terminus have been isolated from soy sauce (20). Thus, these peptides might be deamidated by AsGahA during soy sauce fermentation.…”

Identification and Quantitation of New Glutamic Acid Derivatives in Soy Sauce by UPLC/MS/MS

“…Using gel filtration, ion-exchange chromatography, and paper chromatography, coupled with amino acid analysis, they identified many acidic dipeptides (Glu-Glu, Asp-Glu, Glu-Ala, etc.) considered to contribute to the umami taste of soy sauce [1]. More recent studies [4 -7] questioned the contribution of small peptides, and revealed that amino acids and sodium salts were responsible for this umami taste.…”

Isolation and Identification of the Umami Enhancing Compounds in Japanese Soy Sauce

“…It is known that the umami taste of soy sauce is due to acidic amino acids, including glutamic acid and aspartic acid from soy protein and wheat gluten enzymatic hydrolysate. 6) As for the other contributors, acidic peptides exhibiting umami have been isolated from the soy sauce, 7,8) but the contribution of these peptides to the umami taste of soy sauce was negligible due to low concentrations. 8,9) Other reports have suggested that low-molecular-weight compounds in soy sauce contribute to the salty and the umami taste, 10) and that phenylalanine enhanced the umami taste of soy sauce because of its enhancing effect on that of monosodium L-glutamate (MSG), 11) but the key driver of the umami taste of soy sauce on a molecular level is still unclear.…”