Abstract
In common Satsuma mandarin trees (Citrus unshiu Marc. cv. Sugiyama) of open center and hedgerow type. compositions of sugars, organic acids and amino acids in fruits at different locations within the canopy were studied during a period from July to December, 1977.
The results are given as follows.
1. Sugar constituents detected in the fruit juice were fructose, glucose, and sucrose, and a greater propotion of the total sugars was fructose in the early stage of the fruit growth, but it was sucrose, instead of fructose, at the end of October, regardless of fruiting locations. Glucose content was kept almost constant throughout the period of observation. There was no difference in the total sugar content among fruiting locations in either type of trees.
2. Organic acid constituents detected in the fruit juice were, whether they may be free or in combined form, glutamic, glucuronic, pyro-glutamic, lactic, acetic, pyruvic, malic, citric, succinic, isocitric and α-ketoglutaric acids regardless of fruiting locations and in either type of trees. Citric acid was the main acid, followed by malic acid and glutamic acid, and these three acids strongly determined the fluctuation of the total organic acid content. No consistent tendency could be observed between fluctuations in the main acids or in the minor acids in fruits juice and fruiting locations within a canopy.
3. At each fruiting location, arginine, glutamine, aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, γ-aminobutyric acid, lysine, histidine, arginine and ammonia were detected in either type of trees. The content of proline increased most remarkably with maturation at each location. There was also a great but inconsistent difference in the amino acid composition among various fruiting locations.
Thus, at least in the Seto Inland Sea area, no consistent difference in the contents and compositions of sugars, organic acids and amino acids of the fruit juice was found among fruiting locations within the tree canopy in either type of trees used.
