A yeast extract containing a peptide, such as γ-Glu-X and γ-Glu-X-Gly, wherein X can represent an amino acid or an amino acid derivative other than Cys and derivatives thereof, is prepared by culturing a yeast in a medium containing a peptide such as γ-Glu-X, γ-Glu-X-Gly and X-Gly, and preparing a yeast extract from the obtained cells.same
