Structural and rheological properties of weakly deacetylated glucomannan gels after high-pressure treatment

Abstract

Native glucomannan (Lot A; pH = 5.3) and weakly deacetylated glucomannan (Lot L; pH = 9.1) gels were subjected to high hydrostatic pressure (HHP): 100, 200, 400, and 600 MPa and studied the influence of HHP on the structural and rheological properties of glucomannan gels. HHP improved the conformational stability, reticular deformability and the energy stability of hydrogen bonds in junction zones of the glucomannan matrix for lot A gels. For lot L gels, 600 MPa was needed to increase the energy content of physical bonds enhancing the solid-like character of the glucomannan matrix. Thermal profiles of pressurized lot A gels exhibited thermophobic behaviour and increased the gel-like character up to 90°C as compared with its unpressurized control. For Lot L gels, the rubber-like response was also shown at T > 70°C for the unpressurized sample, and was maintained at 100, 200, and 600 MPa.