ラクチトール

Lactitol (4-o-(|3-D-Galactopyranosyl)-D-glucitol) is a disaccharide sugar alcohol derived from lactose by reduction of its glucose moiety. Lactitol has not been found in nature. It is about 0.4 times as sweet as sucrose.
In vitro studies with galactosidase-containing enzyme preparations have demonstrated that lactitol is hydrolyzed only very slowly. In incubations with human intestinal biopsies, it has been shown that the human intestinal mucosa does not exhibit any significant dis accharidase activity with lactitol as a substrate. The hydrolytic activities towards lactitol and isomalt were only 1.3% of those towards lactose and isomaltulose, respectively. Corresponding exper iments with intestinal preparations of germ-free pigs and convention ally kept minipigs gave similar results. These observations indicate that lactitol is the most slowly digested disaccharide sugar alcohol. However, in vitro investigations with intestinal enzyme prepara tions provide only relative figures on hydrolysis rates. Experiments with humans and 14C-labeled lactitol during jejunal perfusion indi cate that lactitol is virtually not assimilated by the human small intestine. After passage through the small intestine, ingested lac titol reaches the bacterially colonized segments of the gut where intensive fermentation takes place. Short-chain fatty acids (acetate, propionate, butyrate) are the major fermentation end products which are subsequently further metabolized by the host.
Lactitol is slowly fermented in growing cultures by some strepto cocci, actinomyces and lactobacilli. When fed at 25% of the diet to rats that had been inoculated with Streptococcus mutans, lactitol was about equally as cariogenic as sorbitol and significantly less cariogenic than sucrose. Test candies and chocolates sweetened by lactitol are hypoacidogenic in humans tested by plaque pH telemetry. Boiled sweets made with 100% lactitol are rough in texture owing to crystallization, and caused some gastrointestinal upsets in human volunteers. Since lactitol has only one-third the sweetness of sucrose, sweets need an additional sweetening agent for palatability.