Processing of Low Sugar Jams from Fig Pulp Treated with Pectinesterase

저당성 무화과 잼의 제조

  • Hou, Won-Nyoung (Department of Horticultural Crops Breeding, Mokpo National University) ;
  • Kim, Myoung-Hwa (Department of Horticultural Crops Breeding, Mokpo National University)
  • 허원녕 (국립 목포대학교 원예육종학과) ;
  • 김명화 (국립 목포대학교 원예육종학과)
  • Published : 1998.02.01

Abstract

The change of pectinesterase (PE) activity and pectin substances in fig fruit were investigated and low sugar jams prepared by various methods from fig fruit were compared. Fig fruit PE, which began to show the activity at the harvest time, was not inactivated and had slight activity during frozen storage at $-25^{\circ}C$. The amount of alcohol insoluble solid (AIS) and the degree of esterification (DE) of AIS were reduced by its own PE activity. However the intrinsic PE of fig fruit was not enough to make low-methoxyl pectin below 50% of DE. Fig pulp treated by its own PE and combination of fig PE and orange PE could make low-methoxyl pectin. After PE treatments, fig pulp adjusted below pH 4.0 by addition of citric acid kept red colour. Fig Jams processed by various methods had lower soluble solid $(31{\sim}49^{\circ}Brix)$ compared with conventional fig jam. Five kinds of fig jams out of those showed higher score than others in the sensory evaluation. For preparation of the five jams, the fig pulps with or without 1% pectin were treated at $50^{\circ}C$ for 25 minutes with addition of orange PE (200 units/400 g pulp). The treated pulps were added with 0.25% citric acid, 0.7% calcium and 20% cane sugar. The mixed pulps were prepared for jams containing low sugar by hot plate or microwave or refrigeration (excepting the mixed pulp without pectin).

Keywords

fig fruit;pectinesterase;low-methoxyl pectin;low sugar jam