Changes in fructooligosaccharide content of yacon (Smallanthus sonchifolius) tuberous roots during storage
2006
Narai Kanayama, A.(Nippon Veterinary and Life Science Univ., Musashino, Tokyo (Japan)) | Tokita, N. | Aso, K.
Yacon (Smallanthus sonchifolius [Poepp. and Endl.] H. Robinson), an Asteraceae originating from the Andes mountains, has the edible tuberous roots which contain a large amount of fructooligosaccharides (FOSs) of the inulin type. FOSs are important for yacon plant as main reserve carbohydrate, and also have been known as prebiotic and health-improving food ingredients for human diet. During storage of yacon tuberous roots at low- or room-temperature, their FOS content significantly decreased whereas the fructose content increased, indicating that the extent of the changes was dependent on temperature. Freezing storage at -20 deg C was able to prevent the FOSs in tuberous roots from reduction. At low- or room-temperature, it was obvious that the FOSs of a low degree of polymerization (DP) decreased in preference to those of high DP. These results suggested that the accumulated FOSs in tuberous roots were broken down and utilized in order to supply the energy necessary to maintain metabolic activities of tissues, and that the intrinsic FOS-exo-hydrolyzing enzymes specific for FOSs of low DP might be involved in both the reduction of FOSs and the increase of fructose during storage of yacon tuberous roots.
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