308066-66-2

contains fructose, glucose and sucrose 15%

A wide variety of health benefits have been associated with FOS. Beside their favorable nutritional properties, FOS also have excellent technological properties. They can be thought of as low molecular weight, nonviscous, highly soluble dietary fibers. Being nonreducing sugars, FOS do not undergo a Maillard reaction. When purified, the sweetness of FOS is about 30 % that of sucrose. Moreover, it has a well-balanced sweetness profile with no off-flavor and can mask the aftertaste of artificial sweeteners. It is stable above pH 3 and under 140 C.
FOS can be synthesized either by hydrolysis of inulin (e.g. from chicory) or by enzymatic transfructosylation from sucrose. FOS formed by hydrolysis contain longer fructo-oligomer chains, and not all of the b-(2-2)-linked fructosyl chains end with a terminal glucose. FOS naturally occur in several biological materials and can be extracted from, for instance, caprine milk [78], onion [79], asparagus [80], and banana peel.
The FOS-producing enzyme is usually classified as b-D-fructofuranosidase (invertase, EC. 3.2.1.26) or fructosyltransferase (EC. 2.4.1.9). The synthesis is a complex process involving a multitude of sequential reactions leading to the final products. The resulting FOS structures are mainly 1-kestose (GF2), nystose (GF3), and fructofuranosyl nystose (GF4), where G and F represent the glucosyl and fructosyl moieties of the sucrose molecule, respectively. The byproduct of the conversion is glucose, which has been reported to be the main factor decreasing yield during FOS synthesis.
The network of reaction mechanisms for FOS synthesis has been studied by several investigators. Depending on the source of enzyme, the proposed networks differ from each other in their individual reactions and the species produced (e.g.). The mechanism of transglycosylation by b-galactosidases has been long known. GOS are derived from lactose through this mechanism. GOS are carbohydrates built up from glucose and galactose, according to the formula Galn–Glc, where n = 2–20; in general, disaccharides with linkages other than Galb1–4Glc (lactose) are considered GOS as well. The Japanese company Yakult has produced GOS since the early 1990s. Together with their activities on probiotics, they are considered pioneers in the ?eld. Gibson and Roberfroid introduced the concept of prebiotics, which, in combination with a growing interest in prebiotics and the recognition of their functionality, boosted the application of GOS. The ef?ciency of the synthesis of GOS by transgalactosidase activity of bgalactosidases depends on the conditions applied as well as on the enzyme of choice. GOS synthesis is a kinetically controlled reaction; therefore, the enzyme characteristics strongly determine the formation of GOS, GOS structures, and the productivity of the enzyme. Lactose, however, only poorly dissolves in water (18.9 g per 100 g at 25°). To achieve high substrate concentrations, elevated temperatures are thus required. Whereas elevated temperatures increase the reaction rate of oligosaccharides formation, these temperatures can be detrimental to the biocatalyst. On the other hand, high sugar concentrations have been shown to have a stabilizing effect on proteins due to preferential hydration of the protein. This enables GOS synthesis at temperatures higher than the optimum in diluted aqueous solutions. A good example is the b-galactosidase derived from Kluyveromyces lactis, which has a optimum temperature of *40°. The enzyme activity rapidly decreases with increasing temperature in aqueous solutions. Padilla et al. and Matinez-Villaluenga et al., however, performed the synthesis of GOS using the same enzyme at 50°C with a lactose concentration of 250 g/L, indicating the stabilization effect of lactose on the enzyme conformation and stability. GOS synthesis at high temperatures using A. oryzae b-galactosidase was studied by Vera et al. and Huerta et al., using supersaturated or partially dissolved lactose solutions.