Effective change on rheology and structure properties of xanthan gum by industry-scale microfluidization treatment

This study evaluated the ability to change properties of XG by industry-scale microfluidization (ISM). XG was treated by ISM for one pass at 30, 60, 90, 120 MPa and two passes at 120 MPa. Flow behavior of ISM-treated XG((FD)) was investigated, and structural properties were determined by HPSEC-MALLS, SEM, XRD and FITR analysis. Monosaccharide compositions of ISM-treated XG(FD) after dialysis were determined to investigate the way of disrupting chain. ISM treatment significantly reduced apparent viscosity and molecular weight (Mw) of XG. Viscosity of ISM-treated XG((FD)) couldn't be recovered by dissolving in 0.1 M NaCl, implying that treatment induced scission of XG chain in addition to disrupting weak associations between XG. The decrease ratio of Mw reached the maximum (57.19%) after treatment at 120 MPa for one pass, and treatment for two passes did not further reduce Mw of XG, implying that ISM was an effective technology to degrade XG. The change trend of molecular parameters including R-g, PDI, rho and SVg conformed to that of Mw. The alterations of monosaccharide molar ratios for the dialyzed ISM-treated XG((FD)) indicated that ISM treatment broke glycosidic bonds in the main and side chains of XG. Additionally, ISM treatment transformed the morphology from smooth sheet-like into banded even fragmented structure and weakened the organization of XG. Similar characteristic peaks of FTIR spectra demonstrated that ISM treatment had no effect on primary structure of XG. Based on the above results, a model was proposed to illustrate the alterations of XG chain induced by ISM treatment.