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A variation of free sugar and free amino acid contents of apples during the ripening period was determined by HPLC and amino acid analyzer. The research results are as follows: Fructose, glucose and sucrose were present in the apples. The contents of fructose was the highest, followed by the order of sucrose and glucose. The contents of total sugar in Red fuji was relatively higher than that of Fuji. During the ripening period, the contents of fructose increased conspicuously for the harvesting season and then it decreased gradually. The contents of glucose increased gradually for the harvesting season and then it somewhat decreased. The contents of sucrose increased continually, while, the contents of total free sugar reached the maximum for the harvesting season and then it decreased gradually. A variation in the contents of free amino acid and composition during the ripening period didn´t make a significant difference. The major free amino acid of the apples was in the order of aspartic acid, serine, threonine, glutamic acid, histidine, arginine, and alanine. During the ripening period, aspartic acid, threonin, serine, alanine, histidine, and arginine increased gradually. Especially, alanine, histidine, and arginine increased remarkably after the the harvesting season. Glutamic acid, valine, isoleucine, and leucine didn´t show much change. The contents of total amino acid increased little by little as the apples ripened, dranstically increased during the harvesting season and slowly increased or slightly decreased after the harvesting season.
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