Comparative study of the micro-rheological properties and microstructure of edible oil gels prepared by amino acid gelator

Abstract

In the paper, comparative study of the micro-rheological properties and microstructure of edible oil gels prepared by amino acid gelator of N-lauroyl-L-alanine (NLLA) and N-lauroyl-L-alanine dodecylamide (NLLAD). The rheological properties and thermal stability of the edible oil gels were studied by micro-rheology method, and the crystallization of the gel formation process were explored systematically by optical microscopy. Results showed that the rheological properties of the edible oil gels prepared by NLLAD and NLLA considerably changed with the increase in gelator mass concentration at room temperature. At most mass concentrations of the gelator, the four micro-rheological indices of the gel prepared by NLLAD were smaller than those of the gel prepared by NLLA. During the heating process, when the gel prepared by NLLAD reached a stable elastic factor (EI), its equilibrium time and temperature were higher than those of the gel prepared by NLLA. During the cooling process, the time and temperature of the EI that began to rise were less than those of the gel prepared by NLLA. The elasticity, viscosity, and thermal stability of the four edible oil gels were in the following sequence: soybean oil > corn germ oil > olive oil > sesame oil. Microstructures showed that the gel crystallizations differed among different vegetable oils with the two gelators. The crystallization units of soybean oil gel were the smallest, the corn oil gel was irregular fiber, and the crystallization of olive oil and sesame oil was flower like. Moreover, the order of crystallization unit size was opposite to that of the elasticity properties of micro-rheology. The study can provide theoretical data for the viscoelastic and microstructure applications of vegetable oil gels prepared by amino acid gelator.