Evaluation of pasting properties and retrogradation kinetic of a low viscosity potato starch

Abstract

Abstract The aim of this study was to characterise a low viscosity potato starch (LVPS) in terms of its pasting properties and the kinetic of retrogradation. The pasting properties of a commercial sample of LVPS were measured by Rapid-Visco-Analysis (RVA), while the kinetics of retrogradation was assessed following changes in gel strength by mechanical tests (after storage 24 h and 168 h, 4°C) and viscoelasticity by dynamic time sweep (4 h, 4°C). These analyses were complemented by measurements of cold-water solubility, thermal properties, infrared spectroscopy (FTIR) and polarised microscopy. A sample of native potato starch (NPS) was used as a control for comparison. LVPS showed significant differences in pasting properties compared to NPS, with much lower pasting parameters in LVPS (e.g. final viscosity 57.9 cP in LVPS and 2991.6 cP in NPS). However, the dynamic time sweep showed that LVPS behaved as a strong gel during retrogradation, which was consistent with the higher gel strength values obtained by LVPS during storage. The mechanical and rheological response could be explained by differences in crystallinity and number of oxygen bonds, as suggested by the FTIR spectra. Our results also showed that LVPS is not soluble in cold water, which was consistent with calorimetric data and polarised microscopy images. Therefore, LVPS could be used in applications requiring a starch capable of good mechanical response, but from starchy suspensions with very low viscosity.