Seasonal changes of carbohydrates composition in the tubers of Jerusalem artichoke

Abstract

The data on the composition of carbohydrates in Jerusalem artichoke tubers harvested at the end of March after being exposed to frost during winter in soil were presented. The analysis of carbohydrates was also performed during the following period of vegetative growth and intensive photosynthetic activity in summer. Moreover, the composition of carbohydrates in spring tubers was compared with the one in autumn tubers. The tubers of three cultivars Sauliai, Albik and Rubik were applied for the analysis. The amount of fructooligosaccharides in the spring tubers of all cultivars was equal approximately to 80 % of dry matter. The similar amount of fructooligosaccharides was determined in the autumn tubers of both Sauliai and Albik. In Rubik tubers, their amount was about 10 % higher. The average degree of fructooligosaccharides polymerization differed. In the spring tubers of all cultivars, it was equal to three. In the autumn tubers of Sauliai, Albik and Rubik it was equal to 6, 9 and 10, respectively. The highest amount of sucrose equal to 14–18 % depending on the cultivar was found in the spring tubers. The autumn tubers had the low amount of sucrose (1.4–4.3 %), glucose (0.07–0.18 %) and fructose (0.35–0.5 %). The data on the composition of carbohydrates showed that the tubers of Jerusalem artichoke can be harvested in autumn or left in soil for overwintering. However, they should be used for different purposes due to different carbohydrates composition.