Viscoelastic behavior of reconstituted Aloe vera hydrogels as a function of concentration and temperature

Abstract

Viscoelastic properties for reconstituted A. vera hydrogels were evaluated in different ranges of concentration (0.2–1.6%, w/v) and temperature (30–60°C). The storage (G′) and loss (G″) moduli were well described by power function of the frequency (R2 > 0.92). The combined effect of concentration and temperature was optimized for reconstituted gel formation, targeting maximum viscoelastic moduli (G0′ and G′′0) and minimum slope (n′ and n″) values using response surface methodology. The optimum condition selected was 1.6%, w/v at 30°C having higher gel strength [G′0 (47.8 Pa.sn′) and G″0 (27.4 Pa.sn′)], as well as minimum slope values [n′ (0.24) and n″ (0.08)]. Further, the effect of initial aging time on the viscoelastic moduli of optimized sample (1.6%, w/v at 30 ± 1°C) was noticed by fitting the intermediate creep ringing data to rheological models. The viscoelastic moduli (G′J and G′K) increased with aging time (0–180 min) for optimized A. vera hydrogel, as confirmed by Jeffrey’s and Kelvin-Voigt models. The obtained results suggested that optimized conditions for reconstituted A. vera gel formation could be useful to improve the gel strength which could be useful for various food applications.