Abstract: TDF (total dietary fiber), IDF (insoluble dietary fiber), SDF (soluble dietary fiber), CEL (cellulose), HC (hemicellulose), TP (total pectin), Protopectin, WSP (water soluble pectin) and PG, Cx enzymes activities were determined in the peel and pulp of Cara Cara, Newhall navel orange and Tarocco Sanguine at different development stages. The results showed that TDF contents in the peel and pulp of three sweet oranges decreased gradually during the whole developmental period and the change tendency were identical in three varieties. Tarocco Sanguine orange TDF contents were least, Newhall were next, Cara cara most. The change tendency of TDF contents was accord with IDF, but against with SDF. Pectin contents decreased in fruit especially in pulp. WSP contents increased slighty during the later stage. Following the growth of the fruit, the lignin and HC in fruit decreased rapidly. Lignin and HC contents were opposite correlated with Cx activity markedly. PG activity was lower in the early growth period, along with the fruit mature increased quickly, and decreased rapidly after the maximization at the beginning of November.

Key words: Sweet orange, Dietary fibre, Polygalacturonase (PG), Cellulase (Cx)