Carbohydrate changes in olive during fruit ripening

Abstract

Changes in carbohydrate content in olive during fruit ripening in on and off years showed that contents of fruit soluble sugars during fruit development increased up to 90 days after fruit set and then decreased during fruit ripening up to 120 days. A marked temporary increase was evident at the beginning of fruit color changes. The content of reducing sugars in fruit were considerably higher than that of non-reducing ones. In leaves the amount of non-reducing sugars was higher than that of reducing ones. During on-year, content of soluble sugars decreased after a primary increase whereas during off-year a different pattern was observed. Glucose, fructose and mannitol, main sugars of soluble fraction of fruits were in decreasing order. Changes of glucose and fructose content were contrary to each other up to 135 days after fruit set, thereafter concomitant to decrease of glucose and fructose, mannitol content increased. In leaves, mannitol, glucose and fructose are the major components of soluble sugars, with different pattern during on-and off-years where the content of mannitol in off-year was lower than that of on-year. Insoluble sugars of fruit and leaf in off-year were higher than that of on-year. The main constituents of this fraction after hydrolysis were glucose, rhamnose, arabinose, fructose, galactose, ribose, xylose and mannitol, in different amounts. Glucose was the major sugar of fruits in most cases.