Comparative study on gelling properties of low methoxyl pectin prepared by high hydrostatic pressure-assisted enzymatic, atmospheric enzymatic, and alkaline de-esterification

The gel behavior of low methoxyl pectin (LMP) de-esterified by high hydrostatic pressure-assisted enzymatic (HHP-pectin, 400 MPa/40 degrees C/12 min), atmospheric enzymatic (E-pectin, 40 degrees C/2 h), and alkaline method (A-pectin, pH = 12/25 degrees C/25 min) was comparatively investigated, with regard to gel strength, water-holding capacity (WHC), rheological properties, and microstructure of pectin gels. Results showed that the de-esterification method had a strong influence on gelling properties of LMPs. The gelation of all LMPs was significantly affected by pectin, Ca2+ concentration and pH of the solution, but enzymatically de-esterified LMPs formed gels with higher gel strength, WHC and better viscoelasticity than those from alkaline de-esterified method. HHP-pectin gels showed even higher gel strength at the same Ca2+ concentrations and better WHC at the same pH, as compared to those from E-pectin. Moreover, the de-esterification time for HHP-pectin was much shorter than that for E-pectin. These findings indicated that HHP could be a potential alternative for high efficient pectin deesterification, preparing LMPs with better gelling property.