Formation of Antioxidant Multilayered Coatings for the Prevention of Lipid and Protein Oxidation in Oil-in-Water Emulsions: Lycium barbarum Polysaccharides and Whey Proteins

The impact of Lycium barbarum polysaccharides (LBPs) on the physical and chemical stability of oil-in-water emulsions coated by a whey protein isolate (WPI) was investigated. At pH 3.0, the anionic LBP (0.2-0.6 wt %) molecules were electrostatically deposited onto the cationic surfaces of the WPI-coated oil droplets, leading to the formation of stable multilayered emulsions containing WPI-/LBP-coated oil droplets. However, increasing the LBP concentration to 0.8 wt % led to oil droplet aggregation, which was attributed to charge neutralization, bridging flocculation, and/or depletion flocculation. For subsequent experiments, a low (0.2%) and an intermediate (0.6%) LBP dose was used to prepare the secondary emulsions, and then their physical and oxidative stability was studied during 8 days of storage at 37 degrees C. The presence of the multilayer WPI/LBP coatings around the oil droplets inhibited lipid oxidation (reduced levels of lipid hydroperoxides and 2-thiobarbituric acid-reactive substances), as well as protein oxidation (reduced levels of carbonyl formation, sulfhydryl consumption, molecular weight modifications, intrinsic fluorescence loss, and Schiff-base fluorescence gain). The antioxidant effects of the multilayer coatings were greater at the higher LBP concentration. These results suggest that LBP, a natural plant-based polysaccharide isolated from a traditional Chinese medicine, can be used to improve the quality of emulsion-based foods. However, the level used should be optimized to ensure good physical and oxidative stability of the emulsions.

Automated summary

The study showed that Lycium barbarum polysaccharides can improve the quality of emulsion-based foods by enhancing physical and oxidative stability, with a higher LBP concentration leading to greater antioxidant effects. Optimization of the LBP level is necessary to ensure good stability of the emulsions.