The Contents and Composition of Sugars, Acids and Pectic Substances in Several Main Varieties of European Pear

Abstract

The contents and composition of sugars, acids and pectic substances were compared between 5 varieties of european pear. Total sugar contents at harvest time are 9 to 11% in “Bartlett”, “La France” and “Passe Crassan”, and those in “Winter Nelis” after 40 days cold storage and in “Doyenne du Cornice” after 60 days cold storage are 12% and 11% respectively. Main sugar components are sucrose, glucose, fructose and sorbitol in all varieties investigated here. Fructose is most dominant sugar, this ratio to total sugar content occupied 60-70% in “Bartlett”, “La France” and 81-85% in other three varieties. Free acid content at harvest time are 0. 3-0. 4% in “Bartlett” and about 0.2-0.3% in other varieties. The dominant acid is citric acid in “Bartlett” alone, and malic acid in other varieties. Total pectic substances content at harvest time were about 400mg per 100 g of fresh fruit in “Bartlett”, 500-600mg in “Passe Crassan” and 470-690mg in “La France” respectively. Water-soluble ratio to total pectin content was about 20%, sodium hexameta-phosphate-soluble ratio about 10%, and NaOH-soluble ratio about 70%. Water soluble ratio increased to more than 60% with after-ripening, NaOH-soluble ratio decreased to 20-30% in the stage of ripeness suitable for eating.