Influence mechanism of components and characteristics on structural and oxidative stability of emulsion gel

Abstract

In this study, the effects of κ-carrageenan (KC), emulsion droplet size, and tea polyphenols (TPs) on the oxidative stability and structural properties of emulsion gel were investigated. As expected, the results manifested that the higher the KC addition (0.75 %–1.0 %, w/w), the greater the hardness and storage modulus G′ of the gel. Moreover, as the droplet size of emulsion reduced (0.5–1.0 μm), it interacted more strongly with the gel matrix and the oxidative stability of the oil in emulsion gel was enhanced. However, TPs reduced the gel strength by combining with gel matrix and emulsion. TPs exhibited a preferable synergistic antioxidative effect due to the immobilized protection of gel matrix network structure at 4 °C. The oxidative stability of emulsion gel with 0.75 % (w/w) TPs was improved by 96.17 % at 25 °C for 40 days of storage as compared with those without TPs. Low-field nuclear magnetic resonance (LF-NMR) and fourier transform infrared spectroscopy (FT-IR) analysis suggested that the addition of TPs and lower droplet size promoted the formation of a dense gel network structure, which was more tightly bound to the water, and inhibited the retrogradation. This study provides a theoretical basis and guidance for the development of emulsion gel products with favorable oxidative stability and structural stability.