Xiaomin Chen,Hui Wang,Xiaojun Huang,Shengkun Xia,Chunhua Chen,Qixing Nie,Shaoping Nie
This work established an effective method for kale flavonoids enrichment by resins. Resin screening, adsorption kinetics and isotherms, dynamic adsorption and desorption tests were conducted to optimize the appropriate resins and enrichment conditions. The results showed that NKA-9 was the optimum resin. The best adsorption conditions were 0.2 mg/mL flavonoids concentration, 12.5 bed volume (BV) sample volume and 2 BV/h adsorption rate. The desorption conditions were 3 BV of 80% ethanol at 2 BV/h elution rate. Under these conditions, the product purity was 31.16%. The purified flavonoids extract was mainly comprised of Kaempferol-3-O-sophoroside-7-O-diglucoside, Kaempferol-3,7,4′-O- d -triglucoside, Kaempferol-3-O-feruloyl-sophoroside-7-O- d -glucoside, and Kaempferol-3-O-sinapoyl-sophoroside. Moreover, it presented higher scavenging ability against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl ( OH) radical than crude extract. In conclusion, kale flavonoids can be well concentrated by NKA-9 resin and the purified flavonoids extract has good antioxidant activity which can be potentially applied in food, cosmetic or pharmacy industries.
Walnut kernel pellicle, a by-product of the walnut industry, is rich in polyphenols. However, research on walnut kernel pellicle polyphenols (WPP) remains limited, and the composition and bioactivity of WPP are influenced by extraction methods, gastrointestinal digestion, and colonic fermentation. Therefore, this study aimed to optimize subcritical water extraction (SWE) and NKA-9 resin purification of WPP. Next, the changes in WPP throughout simulated gastrointestinal digestion and colonic fermentation were evaluated. The results demonstrated that SWE achieved higher polyphenol yield compared to ultrasound-assisted extraction, with ellagic acid and ellagitannins as the main components. Although digestion and fermentation reduced WPP contents and antioxidant activities, they facilitated the biotransformation of ellagic acid and ellagitannins into urolithins. Meanwhile, WPP modulated the gut microbiota by promoting beneficial bacteria. Additionally, WPP enhanced beneficial microbial metabolites, including short-chain fatty acids and indole derivatives. These findings highlighted the potential of WPP as a functional ingredient for gut health.