A dry matter (DM) assay along with a qualitative and quantitative carbohydrate study were conducted on two Jerusalem artichoke (Helianthus tuberosus L.) cultivars-'Kharkov' and 'Violet de Rennes'. In addition to sucrose, glucose, and fructose, some inulin-type glucofructosans were detected at all stages of development of the tubers. The carbohydrate content was found to average from 65 to 80% DM. The tubers lose a fraction of their carbohydrates in winter-27.6% for 'Kharkov' and 35.6% for 'Violet de Rennes'. RésuméUn dosage de matièré sèche (MS) ainsi qu'une étude qualitative et quantitative de glucides ont été effectués sui deux cultivars de Topinambour (Helianthus tuberosus L.), 'Kharkov' et 'Violet de Rennes'. En plus du saccharose, glucose et fructose, des glucofructosanes ont été détectées pendant les differents stades du développement des tubercules H93015 de Topinambour. Les glucides représentent 65 à 80% MS. Les tubercules perdent une fraction de leurs glucides en hiver, 27.6% pour le 'Kharkov' et 35.6% pour le 'Violet de Rennes'.

Improved culture of Jerusalem artichoke (Helianthus tuberosus L.) for the better production of fructose requires better performing cultivars. Analysis involving 37 cultivars originating from France or overseas showed that among the early cultivars studied, 'Grando' appear to be the richest with 193 mg/g fresh wt of dry matter (DM) and 508 mg/g DM of fructose (as fructan). For fructose production, among the late white cultivars analysed, 'Kharkov' gave the best performance with 179 mg/g fresh wt of DM, 531 mg/g DM of fructose, and 710 mg/g DM of total carbohydrates. The French cultivars 'Miello', 'Dub', and 'Rico' are considered in their group as the most productive with 549, 545, and 540 mg/g DM of fructose, respectively. H94079Resume La rentabilisation de la culture de Topinambour (Helianthus tuberosus L.) pour la production de fructose necessite le choix de varietes tres performantes. Pour cela, une analyse realisee sur 37 cultivars d'origine, Francaise ou etrangere a montre que: Parmi les cultivars precoces etudies, 'Grando' s'avereleplusricheavec 193 mg/g matiere fraiche (MF) de matiere seche (MS) et 508 mg/g MS de fructose. Pour la production de fructose, parmi les cultivars blancs tardifs analyses, le 'Kharkov' presente le plus d'interet avec 179 mg/g MF de MS, 531 mg/g MS de fructose et 710 mg/g MS de glucides totaux. Les cultivars Francais 'Meillo', 'Dubo' et 'Rico' sont consideres dans leur groupe comme etant les plus productifs avec respectivement 549, 545 et 540 mg/g MS de fructose.

The Jerusalem artichoke (Helianthus tuberosus L.) represents an interesting source of carbohydrate because of its high fructose content (75 % of total carbohydrates). An experiment on storage of two varieties of the Jerusalem artichoke tubers ("Kharkov' and 'Violet de Rennes') showed that the quality of tubers was preserved during the first 7 weeks of cold storage. Beyond this period, the loss in total carbohydrate content was evaluated at 0.19% for the 'Kharkov' and 0.26% for the 'Violet de Rennes' variety of the fresh matter/week. Between the seventh and the thirteenth week of cold storage the tubers lost about 16.7 % and 19.1 %, respectively, of their initial carbohydrates. From this study we came to the conclusion that storage at 4 C for the two varieties ('Kharkov' and 'Violet de Rennes') beyond 7 weeks would cause a decrease of general reserves in tubers.