关键词: 甘薯淀粉糊, 触变性, Cross方程, Herschel-Bulkley方程, 动态流变

Abstract: The rheological behaviours of sweet potato starch paste at various concentrations (2%, 5%, 8%, 10% and 20%) and at various temperatures (20℃, 40℃, 60℃ and 80℃) were assayed respectively. The results showed that sweet potato starch paste is a typic non-Newtonian, shear-thinning and thixotropic fluid, whereas the higher the temperature or the lower the concentration, the smaller the hysteresis loopis. The rheological behaviours of sweet potato starch paste are explained better by Cross equation than Power Law equation. Variations of viscosity of Sweet potato starch paste temperature ramp from 20℃ to 90℃ at shear rate of 10s-1 and 100s-1 were also investigated respectively. The results showed that sweet potato starch paste is tempersture-sensitive and suitable for Arrhenius equation. Sweet potato starch paste with low concentration (e.g. 2%), however, exhibits an unique behaviour that the Downlink was above the Uplink, described using Herschel-Bulkley equation. The results exhibits an unique behaviour that the Downlink is above the Uplink, using Herschel-Bulkley equation. The results by dynamic rheological measurement showed that the storage modulus (G’), loss modulus (G") and loss factor(tanδ) of sweet potato starch paste increase sharply from initial gelatinization temperature(ToG’) to maximal gelatinization temperature(TG’max) and decrease sharply over TG’max, that the storage modulus (G’) and loss modulus (G") of sweet potato starch paste increase during cooling, while loss factor(tanδ) decreases during 100～50℃ and increased during 50～20℃.

Key words: sweet potato starch paste, thixotropic property, Cross equation, Hreschel-Bulkley equation, dynamic rheology