Influence of novel fructans produced by selected acetic acid bacteria on the volume and texture of wheat breads

This work presents for the first time the positive functional effects of different fructans produced by acetic acid bacteria on the volume and texture of breads. A total of 21 strains from different genera were screened for their ability to synthesize high amounts of homopolysaccharides from sucrose. Gluconobacter frateurii TMW 2.767, Gluconobacter cerinus DSM 9533, Neoasaia chiangmaiensis NBRC 101099, and Kozakia baliensis DSM 14400 were shown to produce high exopolysaccharide (EPS) yields ranging from 6 to 12 g/L in liquid gluconate media supplemented with 80 g/L sucrose. The isolated, lyophilized polysaccharides of these strains were determined as fructan-like homopolymers via high-performance liquid chromatography analysis and subsequently used as baking ingredients for wheat breads. The addition of each tested fructan in two dosages (1 and 2% w/w flour) caused an increased volume and clear softening effect of fresh wheat breads. Furthermore, a retarded staling of the EPS breads was observed during 1-week storage. The highest values of volume increase were detected for breads baked with 2% fructan of N. chiangmaiensis (6.6%) and K. baliensis (5.5%). The crumb hardness of fresh breads was clearly affected when adding the lowest dosage (1%) of each tested sugar polymer (18-26% softer than control breads). By trend, fructans of N. chiangmaiensis and K. baliensis retarded bread staling more effectively than fructans of G. frateurii and G. cerinus. Remarkably, increased volume, softening, and antistaling of wheat breads were already clearly observed upon addition of each isolated fructan in the lowest tested dosage (1%).