Enzymatic Synthesis of Prebiotic Oligosaccharides

Abstract

Prebiotic oligosaccharides are nondigestible carbohydrates that can be obtained by enzymatic synthesis. Glucosyltransferases can be used to produce these carbohydrates through an acceptor reaction synthesis. When maltose is the acceptor a trisaccharide composed of one maltose unit and one glucose unit linked by an alpha-1,6-glycosidic bond (panose) is obtained as the primer product of the dextransucrase acceptor reaction. In this work, panose enzymatic synthesis was evaluated by a central composite experimental design in which maltose and sucrose concentration were varied in a wide range of maltose/sucrose ratios in a batch reactor system. A partially purified enzyme was used in order to reduce the process costs, because enzyme purification is one of the most expensive steps in enzymatic synthesis. Even using high maltose/sucrose ratios, dextran and higher-oligosaccharide formation were not avoided. The results showed that intermediate concentrations of sucrose and high maltose concentration resulted in high panose productivity with low dextran and higher-oligosaccharide productivity.

Cashew juice containing prebiotic oligosaccharides

“…A solution containing NaOH (120 g/L) and sucrose (300 g/L) was fed into the fermentator to control de pH and to avoid total sucrose depletion in the culture medium. The feed flow rate was intermittent and automatically controlled to keep the pH value at 6.5 for 6 h of fermentation (Rabelo et al 2006). After 6 h of fermentation, the feed flow rate was interrupted and the pH was allowed do drop to 5.2 (optimum pH of enzyme activity and stability) when the process was considered finished.…”

“…However, in medium containing an acceptor (maltose, fructose, glucose, etc.) as substrate, besides sucrose as the second substrate, the enzyme produces prebiotic oligosaccharides Rabelo et al 2006). This reaction is called the acceptor reaction and the ratio sucrose:acceptor affects the dextran and oligosaccharides yield and the degree of polymerization (Rabelo et al 2006;Rodrigues et al 2006).…”

“…instead of dextran chain (Rabelo et al 2006;Rodrigues et al 2006). As glucose units are incorporated into oligosaccharides chain, the degree of polymerization increases.…”

“…Degrees of polymerizations up to 10 units of glucose, with glucose being incorporated by enzymatic synthesis through α-1,6 glycosidic bonds are known as prebiotic oligosaccharides. These oligosaccharides, although present relevant technical applications, are considered of difficult synthesis (Heincke et al 1999;Rabelo et al 2006.…”

“…The initial pH of the culture medium was adjusted to 6.5 with H 3 PO 4 and the medium was autoclaved (121°C/15 min). Activation was carried out in an orbital shaker (Tecnal TE 420) at 30°C and 150 rpm (Rabelo et al 2006;Rodrigues et al 2003) for 12 h. This cell culture was used as inoculums to produce dextransucrase in a fed batch fermentation process. The inoculums amount was 3 % (v/v) of the culture media volume.…”