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Effect of retort treatment on physicochemical properties of high-amylose rice gel made by high-speed shear treatment

Isaka, Keisuke, Shibata, Mario, Osawa, Marin, Sugiyama, Junichi, Hagiwara, Tomoaki
Journal of cereal science 2018 v.79 pp. 335-340
X-ray diffraction, amylose, crystal structure, differential scanning calorimetry, gelatinization, gels, physicochemical properties, retrogradation, rice, storage temperature, viscoelasticity
The effects of retort treatment on rice gels made from rice of three kinds (Aichi125, Mizuhochikara, Momiroman) prepared using high speed shear treatment (HST) were investigated. The high speed shear rate was 1500 rpm. Prepared rice gel samples were stored at 25 °C for 2 months. The retort treatment was applied to the three rice gels. Viscoelastic properties and retrogradation of rice gels were measured using dynamic viscoelastic measurement, X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The higher the amylose contents became, the faster the retrogradation progressed and the higher the increase of the dynamic viscoelastic moduli of the rice gel samples. Only the rice gel made from Aichi125 showed gelatinization behavior in the DSC and XRD measurements past 30 day storage. The relative crystallinity (Cr) in Aichi 125 and Momiroman decreased just after the retort treatment although their dynamic viscoelastic moduli increased. The results indicated that not only the starch retrogradation but also the other factors such as the change of protein induced by the retort treatment affected the physicochemical properties of HST rice gels.