Degradation of exopolysaccharides from lactic acid bacteria by thermal, chemical, enzymatic and ultrasound stresses

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

Abstract

During isolation, exopolysaccharides (EPS) from lactic acid bacteria are subject of thermal, chemical, enzymatic or ultrasound stress of different intensity that may affect macromolecular properties, for instance molecular mass or (intrinsic) viscosity. These parameters are, however, crucial, as they are associated with the technofunctional potential of EPS replacing commercial thickeners in nonfermented products. The aim of this study was to systematically examine treatments EPS are usually exposed to during isolation and to investigate the underlying degradation mechanisms. Solutions (1.0 g/L) of EPS from Streptococcus thermophilus, isolated as gently as possible, and commercial dextran were analyzed for molecular mass distributions as representative measure of molecule alterations. Generally, acid, excessive heat and ultrasonication, intensified by simultaneous application, showed EPS degradation effects. Thus, recommendations are given for isolation protocols. Ultrasonic degradation at 114 W/cm2 fitted into the random chain scission model and followed third-(S. thermophilus EPS) or second-order kinetics (dextran). The degradation rate constant reflects the sensitivity to external stresses and was DGCC7710 EPS > DGCC7919 EPS > dextran > ST143 EPS. Due to their exceptional structural heterogeneity, the differences could not be linked to individual features. The resulting molecular mass showed good correlation (r2 = 0.99) with dynamic viscosity.

Details

Original languageEnglish
Article number396
Pages (from-to)1-15
JournalFoods
Volume10
Publication statusPublished - 11 Feb 2021
Peer-reviewedYes

External IDs

ORCID /0000-0002-1199-3509/work/142248732
PubMed 33670305
Mendeley bcffb9d3-3b90-3394-a5ed-cce17e66480f

Keywords

Keywords

  • Degradation, Dextran, Exopolysaccharides, Lactic acid bacteria, Molecular mass, Random scission model, Shearing, Streptococcus thermophilus, Ultrasound