Browsing by Subject "oat bran gruel"

Exohomopolysaccharides (HOPS) are polysaccharides that are composed solely of glucose or fructose monomers and which are classified according to the linkage type between the monomers (e.g., dextran ?-[1?6]). Several different lactic acid bacteria (LAB) strains produce HOPS from sucrose. It is known that maltose can influence the synthesis of HOPS which can lead to formation of oligosaccharides. In fermented foods, HOPS and oligosaccharides can have both technological impact and prebiotic properties. The aim of this thesis was to investigate the synthesis of HOPS and oligosaccharides in mMRS broths and in oat bran gruel. Lactobacillus reuteri FUA 3048, Lb. reuteri LTH 5448, Weissella cibaria 10M and W. confusa DSM 20194 were used as starter cultures. HOPS and oligosaccharide yields in mMRS broths were analysed by ethanol precipitation and acid hydrolysis. An enzyme assisted method was used in order to quantify linear dextran content in freeze-dried oat gruels. Oligosaccharide profiles were analysed with high performance anion exchange chromatography with pulsed amperometric detetection. In mMRS broths, which contained 25 g/l sucrose (S-mMRS), LAB strains synthesised exosaccharides at concentrations of 0.9–2.3 g/l. Addition of maltose (34 g/l) significantly increased exosaccharide yield. This can be explained by strong malto-oligosaccharide (e.g., panose) synthesis. W. cibaria 10M produced 0.94 g/l linear dextran in S-mMRS broth and at 0.74 g/l in maltose containing broth and W. confusa DSM 20194 synthesised 1.7 g/l linear dextran in both broths. In oat gruel matrix (34 g/l maltose) W. confusa DSM 20194 synthesised 4.6 g/100 g dextran in freeze-dried gruel. In lower maltose concentrations dextran yield increased. Oligosaccharide profiles indicated that Weissella strains and the Lb. reuteri FUA 3048 strain synthesised gluco-oligosaccharides and Lb. reuteri LTH 5448 strain produced erlose. The results of this thesis give further insight in to role of maltose in HOPS synthesis in food matrices.