Organic Acids, Free Amino Acids and Sugars Compositions in Ume (Prunus mume) Extract, and Change of Their Component during Preparation Process of Ume Extract

Abstract

Ume extract is a dark brown and very sour paste which is produced by boiling down fresh ume (young fruits of Prunus mume) juice. The composition of homemade ume extract was analysed with regard to free amino acids, organic acids, sugars and sugar alcohols. Fifty grams of ume extract was made from 1 kg of fresh ume. In all samples the major components were found to be malic acid and citric acid, which amounted to 40-53%. However, the molar ratio of malic acid to citric acid differed according to the time of harvest and the variety of ume. Content of free amino acids was 0.6-1% by weight, the major part of which was asparagine. The major sugars found in fresh juice were fructose, glucose and sucrose. The browning and rapid decrease in both free amino acids and sugars at the final stage of the concentration process suggested the progress of the Maillard reaction. The presence of pheophytin a was also suggested.