FRUCTOOLIGOSACCHARIDES AND PHENOLICS IN FLESH AND PEEL OF SPRING HARVESTED HELIANTHUS TUBEROSUS

The perennial vegetable plant Helianthus tuberosus (Jerusalem artichoke) is an interesting plant as regards functional food constituents.
The tuber flesh of this plant is a rich source for fructooligosaccharides (e.g., inulin) that act as sweeteners that not affect blood sugar level after ingestion.
In the present study, 10 genetic variants of H. tuberosus collected from different locations in Norway were grown in field trial in southern part of Norway.
Tubers were harvested the following spring after being exposed to frost during winter.
Analysis of fructooligosaccharides, sugars, phenols and antioxidant capacity (DPPH) was carried out.
For the variants tested 30–54% of total carbohydrates were fructooligosaccharides and the rest were sugars (mainly sucrose and low levels of fructose). The level of total fructooligosaccharides varied from 20 mg g^-1 (FW) for the variety ‘Bergly’ to approx. 40 mg g^-1 for ‘Kirkeøy’. Kestose and Nystose was abundant fructooligosaccharides in all cultivars.
Analysis of the peel of tubers showed relatively high levels of total phenolics (39–129 mg GAE 100g^-1 FW) and a high antioxidant capacity (98–296 mg ascorbic acid equivalents 100 g^-1). The level of total phenols was correlated to antioxidant capacity (r=0.81). The flesh of tubers contained very low levels of phenols and antioxidant capacity was not detected for any of the clones.

I International Symposium on Human Health Effects of Fruits and Vegetables

R. Seljåsen, R. Slimestad

Helianthus tuberosus, fructooligosaccharides, inulin, phenolics, storage, frost, spring harvest

https://doi.org/10.17660/ActaHortic.2007.744.53