Effects of Eucommia ulmoides leaf powder on the gelatinization, rheology, and gel properties of sweet potato starch

Abstract

This study aimed to explore the feasibility of employing Eucommia ulmoides leaf powder (ELP), which is a novel medicinal and food homologous material, to improve the physicochemical properties of sweet potato starch (SPS) gel. The effects of ELP on the gelatinization, rheology, and gel properties of SPS were investigated. The Brabander viscosity test results showed that ELP could reduce the peak viscosity, trough viscosity, final viscosity, and setback value of SPS. The rheological tests showed that the SPS-ELP gels had shear-thinning behavior, and that the ELP could decrease the apparent viscosity, shear stress, G′, G″ of SPS-ELP gels and make the gels exhibit stronger liquid-like behavior. The X-ray diffraction pattern indicated that the ELP could decrease the relative crystallinity and retard retrogradation of SPS-ELP gels, which was cofirmed by microscopic structure analysis. The ELP had a significant effect on the color difference of the gels, resulting in a yellow-green color. The addition of ELP also reduced the hardness of SPS-ELP gels, and increased the median particle size D50, volume mean diameter D [4,3], and area mean diameter D [3,2] of gel particle size distribution. These findings suggest that ELP has a good potential in improving starch gel properties.