Assessment of fresh Alpinia galanga (A. galanga) drying techniques for the chemical composition of essential oil and its antioxidant and biological activity

Evaluating How Different Drying Techniques Change the Structure and Physicochemical and Flavor Properties of Gastrodia elata

We evaluated the drying characteristics and structure, as well as the physicochemical and flavor properties, of G. elata treated by hot-air drying (HAD), vacuum drying (VD), freeze drying (FD), microwave drying (MD), and microwave vacuum drying (MVD). We found that MD and MVD showed the shortest drying times, while FD and MVD were able to better retain the active ingredients and color of the samples. However, the different drying methods did not change the internal structure of G. elata, and its main components did not fundamentally change. In addition, E-nose and HS-SPME-GC-MS effectively differentiated the volatile components, and 36 compounds were detected by HS-SPME-GC-MS. Of these samples, alcohols and aldehydes were the main substances identified. In particular, MVD samples possessed the most species of organic volatiles, but the FD method effectively eliminated pungent odors from the G. elata. Overall, MVD shows the most obvious advantages, improving drying rate while maintaining the original shape, color, and active components in G. elata. Ultimately, MVD is the preferred method to obtain high-quality dried G. elata, and our drying-method characterizations can be used to investigate similar structural and chemical changes to similar herbs in the future.

Ternary composite degradable plastics based on Alpinia galanga essential oil Pickering emulsion templates: A potential multifunctional active packaging

To reduce the use of petroleum-based plastics and explore multifunctional plastics, this study was conducted to prepare ternary composite plastics by doping Pickering emulsions containing Alpinia galanga essential oil into a polymer network consisting of poly(vinyl alcohol)-acetylated pullulan polysaccharides. Scanning electron microscopy results showed that although incompatible components were present in the composite plastic, compatibility improved with the addition of pullulan polysaccharides, resulting in smooth surfaces and cross-sections, which was consistent with the observation of continuous dark zones and low relative roughness (Ra = 5.51) in Atomic force microscopy. Further, Fourier transform spectroscopy and X-ray diffraction characterization revealed that the composite plastic disrupted the molecular and crystalline structures of the pure PVA, causing the stretching vibration of -OH and the decrease of relative crystallinity. Moreover, this plastic performed optimally at a PVA to pullulan polysaccharide ratio of 75:25, exhibiting good thermal (13.12 J/g) and mechanical properties, low water absorption (70.71 %) and water vapor transmission (1.80 × 10-3 g/m2 s), as well as excellent degradability. In addition, Alpinia galanga essential oil components in the composite plastic provided favorable antioxidant scavenging of DPPH and ABTS and inhibitory effects against Escherichia coli and Staphylococcus aureus. Chicken meat packaging revealed that the plastic maintained sensory parameters such as pH and color by inhibiting the oxidation of proteins and lipids during shelf-life. The findings provide insights into developing innovative, green, multifunctional packaging and broaden the in-depth application of Alpinia galanga essential oil.

Microextraction of essential oils: A review

Liquid phase microextraction (LPME) and solid phase microextraction (SPME) are popular extraction techniques for sample preparation due to their green and highly efficient single-step extraction efficiency. With the increasing attention to essential oils, their evaluation and analysis are significant in analytical sciences. In this review, starting from a brief description of the recent advances in the last decade, the attention has been focused on the up-to-date research works and applications based on liquid and solid phase microextraction for essential oil analyses. Particular attention has been given to the approaches using ionic liquids, eutectic solvents, gas flow assisted, and novel composite materials. In the end, the technological convergence of novel microextraction of essential oils in the future has been prospected.

Fingerprint Analysis of Volatile Flavor Compounds in Crassostrea gigas of Different Ploidy and Gender under High-Temperature Incubation

In this study, diploid, triploid, and tetraploid Crassostrea gigas samples were subjected to gas chromatography and ion mobility (GC-IMS) to identify and analyze volatile compounds and flavor fingerprints under conditions of high-temperature incubation. The GC-IMS technology identified a total of 54 volatile components in C. gigas. The contents of 1-octen-3-ol, butyl pentanoate, p-methyl anisole, and 2-methyl-2-hepten-6-one in male oysters were significantly higher than in females, while the contents of phenylacetaldehyde, benzaldehyde, 2-ethyl-3-methylpyrazine, 2-ethylfuran, and 2,4-hexadienal in female oysters were significantly higher than in males. The contents of non-3-en-2-one-M and 1-pentanol in diploids were significantly higher than in triploids and tetraploids, while the content of 2,4-hexadienal in tetraploids was significantly higher than in diploids and tetraploids. The contents of ethyl acetate, ethyl-2-butenoate, and butanal in tetraploids were significantly higher than those in diploids and triploids. The results of a principal components analysis showed that different samples were relatively independently clustered, allowing the ability to distinguish different oyster samples. The chemical fingerprints of volatile compounds of C. gigas with different ploidy and gender under high-temperature incubation were established, and the volatile substance contours of C. gigas were visualized. The results provide a reference for distinguishing the ploidy and gender of C. gigas under conditions of high-temperature incubation.

Pheophorbide-a as a Light-Triggered Liposomal Switch: For the Controlled Release of Alpinia galanga (A. galanga) Essential Oil and Its Stability, Antioxidant, and Antibacterial Activity Assessment

In this study, Alpinia galanga essential oil liposomes (EO-Lip) were prepared with soybean lecithin and cholesterol as wall materials. A light-responsive liposome (EO-PLip) was designed for the controlled release of A. galanga oil based on the light-responsive properties of Pheophorbide-a. The dependence of Pheophorbide-a on illumination time was proved by UV spectroscopy. Characterization techniques such as UV spectroscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy demonstrated that the essential oils were successfully encapsulated in liposomes. Moreover, the particle size of EO-PLip was 166.30 nm, the polydispersity index was 0.22, the zeta potential was -49.50 mV, and the encapsulation efficiency was 30.83%. Both EO-Lip and EO-Plip have high sustained-release effects on essential oil and showed light-responsive release characteristics under infrared stimulation. The prepared liposomes had good storage stability at 4 °C for 28 d. EO-PLip showed excellent transient antioxidant and bacteriostatic properties based on the ability to respond to light and slow release. This EO-PLip provided a platform for essential oils and might be used as a potent and controllable solution.