Abstract
Changes with aging in the free amino acids, sugars, organic acids, pH, and color of umeshu (Japanese plum liqueur) aged from 1 month to 12 years were studied. The free amino acid content in umeshu markedly increased immediately after mixing with the fruit, sugar crystals and shochu (Japanese distilled sprit), and reached a constant level after approximately one year of storage. Asparagine, the major free amino acid, gradually decreased, while aspartic acid increased during the storage period. The inversion of sucrose was completed within one year of preparing the liqueur. Organic acids increased during the first year of storage and then slowly decreased after that period. No appreciable further change was apparent after 3 years. The pH value of the liqueur remained in the range of 2.8 to 3.0 throughout the storage period. The color of the liqueur gradually deepened with increased storage period. The taste thickened and became stale with increasing storage period. Three-year-old liqueur was most favored by the tasters.
