Rong Li

Lavender ( Lavandula angustifolia ) is an important medicinal and aromatic plant. However, the application of lavender essential oil (LEO) is limited by its instability, low solubility and high volatility. Therefore, to improve the stabilities and antioxidant activities of LEO and thereby expand...

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

The chemical components of an edible spice, sweet ginger (Alpinia coriandriodora D. Fang) essential oil (AEO) were identified by an ultra‐fast gas chromatography electronic nose (E‐nose) and the main components were β‐pinene (27.9%), 1,8‐cineole (17.3%), p ‐cymene (13.5%), camphene (7.3%), myrcene (5.4%), and pseudolimonene (4.3%). The antioxidant activity of each component was evaluated and the mechanisms of scavenging free radical were studied by E‐nose combined with chemical methodology. Decanal and α‐copaene in AEO showed strong scavenging activities against DPPH radical, and the scavenging rates were over 85%. Decanal had a strong scavenging activity for ABTS radical and the scavenging rate was more than 60%. Similarly, terpinen‐4‐ol and eugenol had strong scavenging abilities to OH radical and the scavenging rates were more than 50%. Gas chromatography‐mass spectrography results showed that it was feasible to identify the chemical components of essential oil by E‐nose, and the similarity reached 88.9%. Practical applications Many essential oils have antioxidant activities and can be used in functional foods. In the present work, the antioxidant active components in AEO were identified and screened by ultra‐fast GC E‐nose. We aimed to target the components with strong antioxidant activity quickly and efficiently through the analysis of the reaction process of DPPH, ABTS and OH radicals with a high scavenging rate in a short time. These results indicate that ultra‐fast GC E‐nose can be used to screen the antioxidant active components in the essential oil.

BACKGROUND: Traditional chemical methods were mainly used to evaluate the total antioxidant activity of essential oils. How to determine the bioactivity of each compound in mixtures is an interesting research topic. Nowadays, an ultra‐fast gas chromatography electronic nose (E‐nose) has been gradually used in the detection of volatile compounds, but the screening of the active components of essential oils has not been reported. E‐nose coupled with chemical methodology was established using the essential oil from rosemary (EOR) as a specific application example. The proposed method can both identify the chemical constituents of EOR and quickly screen the antioxidant by comparing the change of chromatographic peak area of every component in EOR before and after reaction with free radicals.RESULTS: Among all chemical constituents in EOR, verbenone, eucalyptol and o‐cymene showed the strongest scavenging abilities in 1,1′‐diphenyl‐2‐picrylhydrazine (DPPH·), 2,2′‐azino‐bis(3‐ethyl‐benzothiazoline‐6‐sulphonate) (ABTS·⁺) and hydroxyl (·OH) radicals, respectively, with scavenging rates of 67.9%, 39.5%, and 69.9%. The reliability and feasibility of using E‐nose to identify chemical constituents of EOR were verified by gas chromatography‐tandem mass spectrometry (GC–MS/MS). The GC–MS/MS results showed that the main components of EOR were α‐pinene (422.2 μg g⁻¹), p‐cymene (208.4 μg g⁻¹), camphor (203.5 μg g⁻¹), verbenone (160.2 μg g⁻¹), and eucalyptol (129.1 μg g⁻¹).CONCLUSIONS: The E‐nose methods can be used as a complementary method to traditional spectrophotometric techniques. Furthermore, this study will be of great significance for the rapid screening of antioxidant active components in essential oils from natural products. © 2020 Society of Chemical Industry