Transglycosylation of Rebaudioside А by β-fructofuranosidase

Rebaudioside A (RebaA) was subjected to β-2.6 transglycosylation with β-fructofuranosidase from Arthrobacter sp. K-1 and sucrose as a source of fructose units. The yield of transglycosylation depends significantly on the concentration of the acceptor, the donor and the enzyme, as well as the reaction time. At the weight ratio of RebА to sucrose of 1: 1, the degree of transfructosylation in 24 hours was only 5.4%, while at a ratio of 1 : 5, it reaches to more than 23%. It was revealed that transfructosylation proceeds more efficiently in the concentrated solutions, the higher the total concentration of sucrose and RebaA, the greater the yield of fructosylated RebA. To determine the effect of рН on transfructosylation, β-fructofuranosidase was incubated with a solution of 1% RebА and 10% sucrose at 40°C for 15 hours at various pH values. It was also revealed that with an increase in the amount of the enzyme, the reaction accelerates. The most optimal were quantities of 50-100 units per 1 g of sucrose. The reaction of transfructosylation of stevioside is examined, and an organoleptic evaluation of fructosylated derivatives of fructosyl-RebА, fructosyl-stevioside and fructosyl-rubuzoside is also shown. Isolation and purification of fructosylated Reba was carried out by ethanol precipitation and purification on the columns filled with macroporous Diaion HP-20 resin. The resulting product is possessing improved sensory characteristics and can be used as low-calorie sweetener.