Tuber Yield Formation and Sugar Composition of Yacon Genotypes Grown in Central Europe

Abstract

Yacon (Smallanthus sonchifolius) is a tuberous root crop native to the Andean region. The eatable tubers contain up to 70% fructooligosaccharides (FOS) on a dry matter (DM) basis. These FOS are not digestible by the human intestinal tract and do not cause an increase of blood glucose level. Therefore, the consumption of yacon tubers offers health promoting benefits. With regard to cultivation, little to no information about yield potential and FOS content as well as sugar composition of diverse genotypes is known. However, this information is crucial for the development of new health beneficial food products out of different genotypes of yacon. In the present study nine different genotypes were studied in a field experiment in 2017 and 2018 regarding their tuber yield formation, sugar yield, and sugar composition. The genotypes red-shelled (‘RG’), brown-shelled (‘BG’), and ‘Morado’ reached the highest tuber yields of 46.6, 43.5, and 41.6 t ha−1 FM, respectively. These three genotypes also had the highest sugar yields in the same order (2.2, 2.0, and 1.9 t ha−1). Considering the sugar composition and sugar content, these three genotypes were outstanding, with a sugar content up to 66% of DM (‘RG’, 2018). With regards to the development of possible food products, cv. ‘Peru’ can be considered as favorable for the fresh market due to high amounts of both monosaccharides and FOS. Genotypes ‘BG’, ‘RG’, and ‘Morado’ seem to offer various options for the food processing industry, due to their high amounts of FOS.