Rheological Effect of Gelatinisation Using Different Temperature-Time Conditions on Potato Starch Dispersions: Mechanical Characterisation of the Obtained Gels

Abstract

Abstract The influence of temperature-time gelatinisation conditions on the gel forming kinetics and final gel mechanical features of commonly used starches as potato starch was studied. The proximate physicochemical properties of potato starch as well as the thermorheological and textural characteristics of the corresponding potato starch gels (native, NPS, and at different GD, PS) were determined. Thermorheological testing at small amplitude oscillatory shear and texture profile analysis were used to evaluate the systems structure evolution and the final gel texture, respectively. High purity (total starch content > 98.5 ± 0.7% dry basis, d.b.), intermediate amylose content (21.2 ± 0.8%), low damaged starch levels (2.7 ± 0.8%), crystallinity (B-pattern) level of 22.9 ± 1.1% and average particle size (60.3 ± 4.3 μm) were the main physicochemical features of tested NPS. Rheological outcomes indicated that only potato starch samples heated at temperatures above 50 °C for tested gelatinisation times were able to form gels. The largest gel strength was identified for NPS, PS70:20 (temperature/time) and PS80 independently of gelatinisation time. Viscoelasticity of PS85 and PS90 gels significantly drop with increasing temperature-time gelatinisation conditions. Temperatures between peak (58 °C) and final (70 °C) gelatinisation temperatures favour the formation of stronger and fully thermal reversible gels, remaining practically invariant until 80 °C. Texture studies indicated that an acceptable linear dependence (R 2 > 0.96) between viscoelastic gel properties determined by rheology and textural parameters can be established.