Scientists from Korea and Denmark have reported the synthesis of novel oligosaccharides with a relative sweetness of about 80 per cent that of sucrose, potentially offering formulators with an alternative sweetener source.
The oligosaccharides, produced by an enzyme isolated from a mutant strain of bacteria called Leuconostoc mesenteroides B-512FMCM, also had the desirable properties of inhibiting carie-forming bacteria, as well as being prebiotic and promoting the growth of friendly gut-bacteria.
"Thermo-, acid-stable oligosaccharides (TASO) potentially can be used as sweeteners for the food and beverages where thermo- and acid-stable properties are required and as potential inhibitors of dental caries," wrote lead author Eun-Seong Seo from the Jeonnam National University.
A number of sweeteners, both natural and artificial, are available to food formulators. Indeed, the sweetener industry is enjoying considerable growth above the industry average as consumers with growing health and weight concerns turn away from sugar-heavy foods and beverages to 'lite' versions.
According to market analysts Freedonia, the sweetener market is set to grow at around 8.3 per cent year on year until 2008: considerably higher than growth in the ingredients industry currently at about 3 to 4 per cent.
"It is well known that [commercially produced oligosaccharides] maltooligosaccharides and isomaltooligosaccharides are acid- and heat-stable carbohydrates. They are less sweet than fructooligosaccharides, susceptible to acid and heat treatment," said Seo.
"As a result, both types have restricted use as additives or sweeteners in foods that require heat treatment or acidic pH during process."
The researchers present their method for synthesizing the novel oligosaccharides in the journal Enzyme and Microbial Technology. Using the enzyme dextransucrase prepared from L. mesenteroides the oligosaccharides were prepared from sucrose.
"Overall, the optimum conditions for the synthesis of oligosaccharides would be obtained at 34 M sucrose concentrations, 2.55.0 U/ml dextransucrase activities at 2845 C until all of sucrose was consumed (around 24 h)," they said.
Stability tests showed that the novel oligosaccharides were resistant to hydrolysis of the glycosidic linkages at 140 degrees Celsius and pH 6.0. The researchers also report that the polysaccharides were stable from pH 2 to 4 at 120 degrees Celsius.
. Over 16 different oligosaccharides were identified and found to effectively inhibit the formation of insoluble glucan, the growth and acid production of the carie-forming bacteria Streptococcus sobrinus. The oligosaccharides were also found to have prebiotic activity by stimulating the growth of probiotic bacteria Bifidobaterium sp.
No information regarding potential further development and industrial interest in the oligosaccharides was available prior to publication, but research is on-going, said the researchers.
"Studies of the physical properties and specific role of each purified oligosaccharide as a prebiotic for the inhibition of type II diabetes and/or an anti-cariogenic sucrose substitute, especially for various oral pathogens, are in progress," they said.
Source: Enzyme and Microbial Technology Published on-line ahead of print. doi:10.1016/j.enzmictec.2006.08.017 "Synthesis of thermo- and acid-stable novel oligosaccharides by using dextransucrase with high concentration of sucrose"
Authors: E-S. Seo, S-H. Nam, H-K. Kang, J-Y. Cho, H-S. Lee, H-W. Ryu and D. Kim