Exploring the Response and Composition of Polyphenols from Juglans sigillata By-Product

Green husk, meal and shell of Juglans sigillata were used as the material to analyze the polyphenol response change of the by-products under different solid to liquid ratio, treatment time, ethanol concentration, treatment temperature and ultrasound power; the types of polyphenols of the 3 walnut by-products were identified and quantified using HPLC(High Performance Liquid Chromatography); the microstructure of the by-products was observed using SEM(Scanning Electron Microscope). The results showed that the polyphenol yield of the three by-products peaked at 60 ℃, and the polyphenol yield response change was different under other influencing factors, but relatively similar. The polyphenol yield of walnut green husk was 41.22 ± 1.35 mg·g⁻¹, the polyphenol yield walnut meal was 36.75 ± 2.01 mg·g⁻¹, the polyphenol yield of walnut shell was 22.68 ± 1.87 mg·g⁻¹ under better extraction conditions; 5 kinds of monomeric phenol identified in 3 by-products were gallic acid, syringate, p-coumaric acid, quercetin and vanillic acid, 4 kinds of monomeric phenol in green husk were gallic acid, syringate, p-coumaric acid, quercetin, 2 kinds of monomeric phenol in shell were gallic acid and vanillic acid, only 1 kind of monomeric phenol in meal was gallic acid. The gallic acid was detected in all by-products. Treatment time and ethanol concentration interaction were positively correlation at the polyphenols content change of walnut by-products, the solid to liquid ratio and treatment temperature were significantly positive correlation(meal), ethanol concentration was significantly positive correlation(shell), and the treatment temperature and ultrasound power were also significantly positive correlation(green husk). After treatment with the same ethanol solution, the polyphenol yield of 70 ℃ green husk > meal > shell The SEM showed that ultrasound treatment could greatly enhance the extraction effect, prompt more and faster exudation of polyphenols.