Flavonoids from bamboo leaves improve the stability of unsaturated fatty acids in the lipids of walnut emulsions

Bamboo leaves are of great economic value and contain several functional components such as flavonoids, lactones and phenolic acids. In this study, the effects of four flavonoids found in bamboo leaves, orientin (OT), isoorientin (IsOT), vitexin (VX) and isovitexin (IsVX), on the oxidative stability and physical stability of walnut emulsions were investigated. These four bamboo leaf flavonoids (BLFs) lowered the peroxide value and MDA (malondialdehyde) value of the emulsions. Adding 0.03% OT decreased the MDA value by 41.54% after 18 d of accelerated oxidation. Adding BLFs maintained the droplet size and microstructure of the walnut emulsions. In an emulsion containing 0.03% IsOT, the unsaturated fatty acid level decreased by only 1.75%. The results on the residual amounts of BLFs in emulsions were consistent with the lipid hydroperoxide and MDA experiments, but their effectiveness levels were different. Adding BLFs significantly enhanced the oxidative stability of the walnut emulsions. Consequently, BLFs have a good potential as natural antioxidative stabilizers in emulsions for industrial products.