Vietnam has diverse and long-established tea plantations but scientific data on the characteristics of Vietnamese teas are still limited. Chemical and biological properties including total polyphenol and flavonoid contents (TPCs and TFCs), antioxidant activities (DPPH, ABTS, FRAP, and CUPRAC), as well as the contents of caffeine, gallic acid, and major catechins, were evaluated for 28 Vietnamese teas from North and South Vietnam. Higher values of TPCs and TFCs were found for green (non-oxidised) and raw Pu’erh (low-oxidised) teas from wild/ancient tea trees in North Vietnam and green teas from cultivated trees in South Vietnam, as compared to oolong teas (partly oxidised) from South Vietnam and black teas (fully oxidised) from North Vietnam. The caffeine, gallic acid, and major catechin contents depended on the processing, geographical origin, and the tea variety. Several good Pearson’s correlations were found (r² > 0.9) between TPCs, TFCs, the four antioxidant capacities, and the content of major catechins such as (–)-epicatechin-3-gallate and (–)-epigallocatechin-3-gallate. Results from principal component analysis showed good discriminations with cumulative variances of the first two principal components varying from 85.3% to 93.7% among non-/low-oxidised and partly/fully oxidised teas, and with respect to the tea origin.

The Japanese mint (Mentha arvensis L.) is known as a culinary and medicinal herb widely cultivated in several countries. The mint essential oil is considered as one main source of menthol. In this study, the Japanese mint collected from the Central Highlands of Lam Dong Province (Vietnam) was extracted the essential oil by hydro-distillation (HD) and microwave-assisted extraction (MAE). Different extraction parameters were investigated, involving mint leaf drying periods (30, 60, and 90 mins) at 50 °C, material to water ratios (1:4, 1:6, 1:8, and 1:10 for HD and 1:1, 1:1.5, 1:2, and 1:2.5 for MAE), extraction durations (60-180 for HD and 10-25 mins for MAE), and microwave energy (230, 380, 540, and 700 W) in order to discover the conditions with the highest yields for both HD and MAE. The GC-MS was used to determine the oil chemical constituents. For dried mint leaves (nearly 40 % moisture), the highest oil yield of 0.0832 mL g⁻¹ (dried weight) was recorded, and the content of menthol was up to 70.60 % extracted by MAE whilst 0.0510 mL g⁻¹ of yield (dried weight) and lower menthol (62.80 %) were obtained from HD. Besides, menthol, trans- and cis-menthone were found at relatively high concentrations for both HD and MAE (20.19-16.30 and 4.62-5.01 %, respectively). Compared to HD, MAE exhibited higher oil yields and menthol contents, but lower distillation time, resulting in more effective extraction performance of MAE.

Ciprofloxacin, being a widely used antibiotic agent, has sparked growing interest in the field of molecularly imprinted polymers (MIP) for its selective recognition and removal. This review provides a comprehensive analysis of the recent advances in the synthesis and applications of ciprofloxacin-imprinted polymers. The examination of synthesis compositions for the preparation of these polymers includes thorough discussions on functional monomers, crosslinkers, initiators, and solid supports. Various imprinting techniques, including bulk, precipitation, co-precipitation, and surface polymerization, have been assessed for the fabrication of the imprinted polymers. Furthermore, the advancing imprinting techniques, encompassing nano-scale imprinting, multi-functional monomers, multi-template imprinting, and electrochemical imprinting, are also highlighted. Additionally, an extensive exploration of the diverse applications of these polymers is also presented. These applications encompass selective separation and removal of ciprofloxacin from environmental samples, visual and electrochemical detection in complex matrices, their use as a stationary phase for HPLC, drug release, and photocatalysis. This review offers valuable insights into the current advancements and potential future directions in the development of ciprofloxacin-imprinted polymers, emphasizing their importance in diverse analytical and environmental applications.

Chitosan, a byproduct of the food industry, has garnered increasing attention due to its advantages in food preservation. This study reports on the preparation of an antibacterial chitosan membrane: 1.0% (w/v) chitosan and 200 rpm stirring at 60oC for 30 minutes, resulting in the highest inhibition zone of E. Coli (21 mm). Regarding its mechanical properties, the membrane exhibited a tensile strength of 21.95 MPa and elongation of 26.42%. The membrane's physical properties included a moisture content of 23.88 ± 1.39%, solubility of 24.05 ± 1.20%, swelling degree of 216.4 ± 5.64%, and transmittance of 86.18 ± 3.79%. The chitosan membrane functions as a barrier covering the surface of jackfruit and maintains its quality, including color and texture, even after seven days of preservation. In contrast, the non-preserved jackfruit exhibited signs of discoloration. Additionally, the non-preserved sample showed a total aerobic microorganism approximately twice as high as the chitosan membrane preserved sample.