Sugar Alcohols (Polyols) - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 67

disaccharides like lactose. The stability of lactitol in the presence of alkali is markedly higher than
that of lactose. The stability of lactitol in the presence of acids is comparable to that of lactose
(Wolfrom et al. 1938). When heated at 100°C for 4 h at pH 1 and 2 (adjusted with HCl), the rates of
hydrolysis of 10% lactitol solutions are 5.6% and 1.4%, respectively. The solutions remain colorless
under these conditions. The comparable hydrolysis of lactose are 5.4% and 1.3%, respectively. Like
other sugar alcohols, lactitol shows only a very slight discoloration, as a result of caramelization
reactions, when heated at temperatures of 150°C-200°C (van Velthuijsen 1979).
It is currently used as a bulk sweetener in calorie-controlled foods. Discovered in 1920, it was
irst used in foods in the 1980s (van Velthuijsen and Blankers 1991). The relative sweetness level of
lactitol is about 35% as compared to sucrose and 110%-140% to lactose (Uyl 1987; van Velthuijsen
1979; Siijonmaa et al. 1978). Lactitol has a clean sweet taste that closely resembles the taste proile
of sucrose. Its mild sweetness makes it an ideal bulk sweetener to partner with low-calorie sweeten-
ers such as acesulfame-K, aspartame, neotame, saccharin, and sucralose (Van Es et al. 1986).
Lactitol offers many interesting applications for the food industry, especially for the ields of
dietetic and low-caloric foods. In many products, lactitol can replace sucrose without drastic changes
in formulations or manufacturing processes. Depending on the speciic application, lactitol can be
used as a solution (e.g., for jams, beverages, hard candies) or as the crystalline, nonhygroscopic
monohydrate (e.g., for chocolate, chewing gum, bakery products; van Velthuijsen 1979).
As a sweetening ingredient, lactitol has a low glycemic index, does not induce an increase
in blood glucose or insulin levels, and contributes half the calories of most other carbohydrates
(2 calories per gram). Foods using lactitol to replace sugar can be used by people with diabetes, giv-
ing them a wider variety of low-calorie and sugar-free choices. Lactitol is not metabolized by oral
bacteria, which break down sugars and starches to release acids that may lead to cavities or erode
tooth enamel (Grenby and Desai 1988).
In a patent application (Hayashibara 1974), it was demonstrated with rats that lactitol inhibits the
absorption of sucrose and also the formation of cholesterol. The increase in the blood glucose con-
tent after consumption of a 1:1 mixture of sucrose and lactitol was about half of the increase after
consumption of sucrose only (the amount of sucrose intake was the same), whereas the formation of
liver glycogen with the 1:1 mixture was only one-ifth of that with only sucrose. Diets with added
cholesterol showed that the inclusion of lactitol in the diets of rats resulted in a reduction to about
50% of the contents of liver cholesterol and of the total serum cholesterol (van Velthuijsen 1979).
Unlike the metabolism of lactose, lactitol is not hydrolyzed by lactase. It is neither hydrolyzed
nor absorbed in the small intestine. Lactitol is metabolized by bacteria in the large intestine, where
it is converted into biomass, organic acids, carbon dioxide, and a small amount of hydrogen. The
organic acids are further metabolized resulting in a caloric contribution of 2 calories per gram (car-
bohydrates generally have about 4 calories per gram; van Velthuijsen and Blankers 1991).
Very little of this disaccharide polyol is absorbed, perhaps 2% as lactitol and its hydrolysis prod-
ucts galactose and sorbitol. This is due to a very low activity of β-galactosidase in the human intes-
tine (Grimble et al. 1988; Nilsson and Jagerstad 1987). The liver readily uses absorbed galactose
and sorbitol in either hepatic glycogen storage or hepatic glucose production. Unabsorbed lactitol
is completely fermented with a stoichiometry giving a generous yield of H 2 gas in vivo and in vitro
(Livesey et al. 1993) and butyric acid in vitro (Clausen et al. 1998).
Lactitol is fermented in the colon and consequently has beneicial effects on the colonic micro-
lora. A reduction in the pH of the colon, along with an increase in probiotic bacteria and a sig-
niicant reduction in potential pathogens, emphasizes the beneicial effects of lactitol. In essence,
lactitol functions as a prebiotic (van Velthuijsen and Blankers 1991).
Lactitol has been shown to be as effective as lactulose for the treatment of chronic stable hepatic
encephalopathy, but it was more acceptable as a medication (Lanthier and Mosgan 1985; Patil et
al. 1987; Scevola et al. 1989). Its laxative effect and other side effects (i.e., osmotic diarrhea, latu-
lence) diminish when administered regularly. The metabolism of lactitol is different from that of