Improvement of the stabilities and antioxidant activities of polyphenols from the leaves of Chinese star anise (Illicium verum Hook. f.) using β‐cyclodextrin‐based metal–organic frameworks

BACKGROUND Polyphenols extracted from plants are usually highly unstable and rapidly transformed into various reaction products during food and drug processing, thus limiting their applications. To improve the stability and solubility of polyphenols from the leaves of Chinese star anise (Illicium verum Hook. f.), and hence to expand their application to food and medicine, the extracted anise leaf polyphenols (ALPs) were microencapsulated using β‐cyclodextrin (β‐CD) and cyclodextrin‐based metal–organic frameworks (β‐CD‐MOFs). RESULTS The optimum inclusion rate of ALP/β‐CD‐MOFs was 97.80% at a core–wall ratio of 1:10. Meanwhile, the stabilities, solubilities and antioxidant activities of the polyphenols before and after inclusion were compared. The results showed both the stabilities and solubilities of ALP/β‐CD‐MOFs were significantly improved compared with those of ALPs and ALP/β‐CD, suggesting the potential of β‐CD‐MOFs as newer and better carriers than β‐CD for polyphenols in food industry applications. The free radical (including superoxide, hydroxyl and DPPH radicals) scavenging activities were also improved by microencapsulation. Superoxide radical scavenging reaction also showed slow‐release property of ALP/β‐CD‐MOFs. The formation of the inclusion complex was further confirmed using Fourier transform infrared spectral characterization. CONCLUSIONS Microencapsulation with β‐CD‐MOFs could expand the application scope of ALPs, and it is more effective than encapsulation with β‐CD. This is important for a better understanding and application of this useful traditional Chinese plant. As a new material with high efficiency and edibility, β‐CD‐MOFs are not limited to the chemical field, but also have potential in new areas of food, medicine and healthcare products. © 2020 Society of Chemical Industry