Organic Acids in Citrus Fruits. II. Seasonal Changes in the Orangea

Abstract

SUMMARYOrganic acids were quantitatively determined by silicic‐acid chromatography in juice of Valencia oranges sampled from trees over a 16‐month period, and in the juice, albedo, and flavedo of Washington Navel oranges sampled over a 12‐month period. Results obtained prior to late maturity generally agreed with existing data, but previously unreported changes occurred during and after late maturity. In the juices, citrate predominated, but declined on a per‐fruit basis in late season; malate appeared at a low level. In the Navel flavedo and albedo, oxalate decreased and malonate increased. Through most of the season, albedo acid composition was comparable to that of diluted flavedo, but in the latest sample, malonate predominated in the flavedo and oxalate predominated in the albedo. Malate appeared in low, decreasing amounts in the peel, with lesser amounts of citrate. These four acids accounted for 30–50% of the total anions in the peel fractions.