Unlike most vegetable crops, asparagus, a hardy perennial plant, is commonly consumed and appreciated because it is low in calories and provides substantial amounts of reducing sugars and a very low amount of fructooligosaccharides (FOS), and these fructosyl polymers are well known for their health benefits.1) The chemical characteristics of the spears are markedly affected by temperature, 2) growth conditions 3) and harvest date. 4) Carbohydrates are major constituents of asparagus spears and contribute considerably to their quality.1) The main carbohydrates in asparagus spears are glucose, fructose and sucrose, 2,4) while the presence of FOS has never been reported. In asparagus carbohydrates are translocated from storage roots to spears, where they are hydrolyzed into hexoses and used during the catabolic activities of the spears.4) Thus, soluble carbohydrate levels decline particularly during the first hours after harvest, and this decline triggers deterioration in the spears. 5,6) While little FOS are detected in aerial parts of asparagus, it remains still unclear the reason for the difference of FOS content between the top and the bottom parts of the spears. On the other hand, the role of FOS in spears tissues is also unknown. It is not clear if their presence results from simple translocation from roots to spears to provide energetic substrates, or whether they are translocated to play specific roles such as osmoregulation, or to partially compensate for the rapid decline of sucrose in tips. Numerous investigations have been carried out on the structures, 7 11) enzymology 12) and molecular biology 13) of FOS in roots of asparagus and such research works were recently reviewed by Shiomi et al.,14) but there have been no reports on their presence in aerial tissues. Although many studies have focused on the carbohydrate content of edible spears after harvesting, few studies have focused on soluble and reducing sugars, including soluble invertase, while no investigations have been carried out on FOS and their metabolizing enzymes in asparagus spears.From the technological point of view, freshly harvested spears deteriorate rapidly at ambient temperatures, 1) and have a short shelf life, which is strongly related to respiratory activity.15) This postharvest deterioration is accompanied by biochemical changes, particularly in spear tips J. Appl. Glycosci., 54, 187 194 (2007) Abstract: Fresh spears of asparagus were stored in the dark at 4, 10 or 20 C for 2 weeks. During storage contents of glucose, fructose, sucrose, 1-kestose, neokestose and nystose, and activities of invertase, 1-kestose hydrolyzing enzyme (1-KHE), sucrose: sucrose 1-fructosyltransferase (1-SST), fructan: fructan 1-fructosyltransferase (1-FFT) and fructan: fructan 6 G -fructosyltransferase (6G-FFT) were determined in the top, middle and bottom portions of the spears. A gradient was observed, from the bottom to the top, for glucose, fructose and sucrose which constitute the major proportion of carbohydrates, while fructooligosaccharides, ne...

Fructooligosaccharides (FOSs) are short and medium chains of fructose in which two to nine fructosyl units are bound by β 2,1 glycosidic linkages and a glucose molecule is present at the end of the chain joined by an α 1,2 glycosidic bond. Fructooligosaccharides occur in various plants such as onions, asparagus, artichokes and garlic. 1)Short chain FOSs (sc FOSs), such as 1 kestose, nystose and 1F β fructofuranosylnystose can also be enzymatically synthesized from sucrose. 2,3) Fructooligosaccharides are prebiotics that have been studied in detail and they are widely used as a food ingredient. 4 6) A commercially available FOS product comprises a mixture of sc FOSs.4) The primary physiological function of FOSs is the preferential stimulation of colonic Bifidobacteria. The effect has been confirmed in experimental animal models and in humans.7 10) Other physiological functions of FOSs include the improvement of calcium bioavailability, the modulation of lipid metabolism and the inhibition of potential pathogen metabolism. 5,11,12) These functions are mainly due to the indigestibility 13) and selective fermentability of FOSs in the gastrointestinal system. 14)Studies have recently focused more on the immunomodulating effect of oligosaccharides.15,16) Nakamura et al . 17) reported that FOSs enhance the IgA response in the intestine of infant mice and Hosono et al . 18) also showed that the amounts of fecal IgA and of IgA secretion by Peyer s Patch cells are increased in FOS treated mice. Furthermore, Nicole et al . 19) and Pierre et al . 20) demonstrated that dietary FOSs influence gut associated lymphoid tissue.Although beneficial colonic bacteria proliferation and short chain fatty acid production in the gut are thought to be involved in the action mechanism of FOSs on the immune system, details have not been fully established. Furthermore, whether the prebiotic and immunomodulating activities differ among FOSs in vivo and in vitro remains obscure.We investigated the effects of 1 kestose and nystose, which are major components of a dietary FOS product, on intestinal microorganisms and on the splenocyte response to mitogenic stimulation in mice. MATERIALS AND METHODS Animals.Female 6 week old BALB c mice obtained from Charles River Japan (Yokohama, Japan) were maintained at 22 24 C and around 50% relative humidity under a 12 h light dark cycle. A commercial diet (CE 2, Clea Japan, Tokyo, Japan) and water were available ad libitum. The mice were separated by body weight into three experimental groups consisting of five animals. The experimental protocol was approved by the Animal Experiment Committee of Rakuno Gakuen University and the animals were managed in accordance with the Guide for the Care and Use of Laboratory Animals of the same institution. Bacterial strains. Lactobacillus reuteri JCM 1081, Lactobacillus murinus JCM 1717 T and Lactobacillus intestinalis JCM 7548T purchased from the Japan Collection of Microorganisms were cultured at 37 C in MRS medium for DNA extraction.Preparation and administration o...