Variation of total FOS, total IOS, inulin and their related-metabolizing enzymes in burdock roots (Arctium lappa L.) stored under different temperatures

摘要

Burdock roots were stored for six weeks at three temperatures, 0, 15 and 20pC, and activity of sucrose hydrolase (SH), 1-kestose hydrolase (1-KH), inulin hydrolase (InH), sucrose:sucrose 1-fructosyltransferase (1-SST) and fructan:fructan 1-fructoslytransferase (1-FFT) were assessed. Simultaneously, total fructooligosaccharides (FOS), total inulooligosaccharides (IOS) and inulin were also assessed during storage. During storage, SH showed an irregular variation at 15 and 20pC, and was significantly higher at 0pC showing a continuous increase during the storage period. 1-KH decreased progressively at 15 and 20pC, but showed a sharp increase at 0pC after two weeks and decreased afterwards. InH showed a different although more regular pattern by decreasing progressively at 0, 15 and 20pC. However, the decrease was more significant at 15 and 20pC during the first two weeks, while at 0pC the decrease was significant after four weeks storage. 1-SST and 1-FFT activities decreased progressively in a pseudo-linear regression during storage, and showed similar patterns. At 15 and 20pC, total FOS increased during the first three weeks then decreased, while at 0pC FOS increased progressively during storage. Total IOS increased during storage, however, this increase was much higher at 0pC than that observed at 15 and 20pC. Inulin content decreased during storage and final content was lower at 20pC. The inulin to total FOS plus total IOS ratio decreased sharply during the first two weeks of storage, then progressively during the last four weeks, while the ratio of hydrolyzing to synthesizing activities was quite stable at 15 and 20pC, but showed a peak at 0pC after two weeks. The results suggest that carbohydrate metabolism in stored burdock depends partly on temperature and other physiological factors.