Study On The Changes Of Pectin In The Citrus Peric Arp During Different Storage Conditions

The purpose was to investigate the quality changes of citrus peel in storage, the article ta ke Shimen maidarin, Xiangxi ponkan and Jiangyong shaddock as raw materials and studies th e total pectin content, water soluable pectin content and degree of methylation in peel. The i ndex is measured every30days and the methylesterification in madarin peel pectin is research ed.It shows the madarin peel total pectin contents decrease in general, then change a lot in p rophase and stabilize in anaphasis in normal temperature with dry basis,-18℃and-40℃in f resh (the same below), that fall by8.13%,8.67%and3.12%on the300th day compared be fore storing; the water soluable pectin contents increase in prophase, then decrease slightly an d the growths are21.95%,15.68%and10.07%by the end; the degrees of methylation declin e in general process and the decreases are12.97%,10.59%and6.02%respectively by the en d.The ponkan peel total pectin contents are highest before storing, then decline sharply in t he early months, which increase slowly aferwards and stabilize in anaphasis, decreases are23.18%,17.90%and10.44%; the water soluable pectin content trends are complex, which decli ne in prophase with flat late. Except for the1.11%growth in fresh peel storing at-18℃, the other two fall by0.26%and3.08%by the end; the decreases of degrees of methylation are21.09%,11.95%and3.14%and the changes are inversely related to the water soluable pecti n contents in anaphases.The shaddock peel total pectin contents are increase in prophase, then decline aferwards, t he decreases are10.12%,3.49%and2.54%. The fresh peel water soluable pectin content tren ds are similar:they increase slowly in prophase, stabilize obviously in metaphase and increas e in anaphasis, the growth are10.08%and2.19%, but that the general increasing trends in dr y slowly decline in prophase, obviously increase in metaphase and decline after reaching pea k; the degrees of methylation are inversely related to the water soluable pectin contents with growths in fresh(2.09%and2.39%), and the increase(16.95%) in dry.The methylesterification in madarin peel pectin shows that the optimums respectively are as follows:concentrade sulfuric acid8.0mL, methonal52.5mL, time5.0h, temperature50℃; concentrade sulfuric acid9.0mL, methonal50.0mL, time6.5h, temperature55℃; concentrade sulfuric acid7.0mL, methonal50.0mL, time6.0h, temperature60.0℃, the degrees of methylat ion incline by24.87%,28.03%and31.55%compared with the traditional methods of extracti ng pecion.