Sugar Alcohols (Polyols) - Sweeteners: Nutritional Aspects, Applications, and Production Technology - page 65

Biocatalyst

1. Step sucrose (nonreducing) Isomaltulose (reducing)

Hydrogenation

2. Isomaltulose 6-O-α--glucopyranosyl--sorbitol (1,6-GPS) + 1-O-α--glucopyranosyl-

-mannitoldihydrate(1,1-GMP)

Figure 3.14 Production of isomalt from sucrose.

generally does not react with other components of the formulation. It can usually be processed in
plants designed for sucrose as the raw material. Isomalt is used primarily for its sugar-like physical
properties. It has only a small impact on blood sugar levels and does not promote tooth decay. It has
2 kcal/g, half the calories of sugars (Wohlfarth 2006; Ndindayino et al. 2002).
Due to its properties such as taste, mouthfeel, low calorie content, carcinogenicity, suitability to
diabetics, and low hygroscopicity, it offers several advantages over most polyols when formulated
in pharmaceutical dosage forms, particularly when used as a tablet excipient. Isomalt is typically
blended with a high-intensity sweetener such as sucralose, so that the mixture has approximately the
sweetness of sugar (Strater 1989; Fritzsching 1993).
Although isomalt-containing tablets can be manufactured by direct compression, the drug con-
centration of these tablets was limited to 30% as higher drug loads yielded tablets of unacceptable
quality. However, literature reports indicated that the compression properties of polyols were suc-
cessfully enhanced when these products were melted prior to compression (Kanig 1964; Serpelloni
1990). The melting range of isomalt is between 145°C and 150°C, and no decomposition is detected
when the product is melted (Cammenga and Zielasko 1996); this material can be thermally treated
using the hot stage extrusion technique (melt extrusion). Furthermore, neither browning reactions
nor caramel tasting was observed after melting of isomalt (Strater 1989; Fritzsching 1993).
However, like most sugar alcohols (with the exception of erythritol), it carries a risk of gastric
distress, including latulence and diarrhea, when consumed in large quantities. Therefore, isomalt
is advised not to be consumed in quantities larger than about 50 g per day for adults and 25 g per
day for children. Isomalt may prove upsetting to the stomach because the body treats it as a dietary
iber instead of as a simple carbohydrate. Therefore, like most ibers, it can increase bowel move-
ments, passing through the bowel in virtually undigested form. As with other dietary ibers, regular
consumption of isomalt might eventually lead one to become desensitized to it, decreasing the risk
of stomach upset (Wohlfarth 2006).
Several studies including noninvasive methods in human subjects and methods in animals
(Livesey 1990a,b, 2000) on glycemia and insulinemia suggest that 0% to 14% of isomalt is available
as carbohydrate in man. On the basis of the energy values of isomalt, it is concluded that approxi-
mately 90% isomalt is fermented in the colon, with a stoichiometry in vivo and in vitro indicat-
ing relatively little H 2 gas production (Brooks 1995; Dutch Nutrition Council 1987; Life Sciences
Research Ofice 1994; Livesey 1992; Livesey et al. 1993).

3.4.3 Lactitol

Lactitol (4-O-α-d-galactopyranosyl-d-glucitol; Figure 3.15) is a synthetic disaccharide sugar
alcohol produced by catalytic hydrogenation of the glucose moiety of lactose (Abrahamse et al.
1999; Anonymous 1988; Soontornchai et al. 1999). It has a good solubility in water of 57.1 g/100 g
solution at 20°C, which is roughly in the range of that of sucrose (66.7 g/100 g solution). With
increasing temperature, the solubility of lactitol rises considerably, exceeding the solubility of
sucrose at temperatures above about 50°C. In contrast to that, the solubility in ethanol (0.75 g/100 g