Hue University Journal of Science: Natural Science

Effect of extraction conditions and vacuum evaporation temperature on recovering phenolic compounds from germinated adzuki beans (Vigna angularis)

2026-05-07T14:27:27+07:00

This study investigates the factors affecting the extraction of polyphenolic compounds from germinated adzuki beans (Vigna angularis) via ultrasound-assisted extraction and to evaluate the antioxidant activity of the quality of obtained extracts. The parameters included ethanol concentration (60–80%), extraction time (30–60 min), solid-to-solvent ratio (1:5–1:20, w/v), and vacuum evaporation temperature (55–75 °C). The results indicate that the most suitable extraction conditions were 70% ethanol and 50 min extraction with a solid-to-solvent ratio of 1:15 (w/v). Under these conditions, the total phenolic content reached 13.76 mg GAE/g DW, and the total flavonoid content reached 2.38 mg CAE/g DW. In addition, the antioxidant activity of the extract reached 34.18 µmol TE/g DW as determined with the DPPH assay and 39.52 µmol TE/g DW with the ABTS assay. The vacuum evaporation at 60 °C effectively preserved both the phenolic compounds and the antioxidant activity of the extract. The findings of this study provide a scientific basis for utilising germinated adzuki beans as a promising source of natural antioxidant compounds in food and functional food applications.

Effects of harvest maturity, steaming time and heat pump drying on phenolic content and antioxidant activity of Black ginger (Distichochlamys orlowii) powder

2026-05-20T10:06:09+07:00

This study focused on the effects of harvest maturity, steaming time and heat pump drying temperature on the total phenolic content (TPC) and antioxidant activity (IC₅₀) of Black ginger powder (Distichochlamys orlowii). The results indicated that the physiological ripening stage plays a decisive role in raw material quality; specifically, the 11-month post-planting harvest time was optimal with high total soluble solids (TSS) and high reducing sugar content, while there was an increase in TPC combined with a decrease in IC₅₀ values compared with earlier stages. In the pre-treatment stage, saturated steaming for 2 minutes significantly enhanced TPC and improved antioxidant capacity (achieving the lowest IC₅₀). Regarding the dehydration process, a heat pump drying temperature of 55 °C was the best for preserving heat-sensitive bioactive compounds, resulting in a Black ginger powder product with a TPC of 3.44 mg GAE/g DW, the lowest IC₅₀ value (451.56 µg/mL), and a solubility of 25.75%. The research results are an important scientific basis for standardising the processing of a Black ginger powder, which is rich in bioactive compounds and has high antioxidant activity.

Removal of tetracycline from water environment using electrophoretic deposition method

2026-05-08T09:20:08+07:00

The paper presents the results of a study using the electrophoretic deposition method to remove tetracycline from the water environment. Factors, namely pH (pH 2), applied voltage (8.0 V), deposition time (15 minutes), NaCl electrolyte concentration (1.0 g/L), and the initial iron (III) oxide /graphene oxide concentration (50 mg/L), were investigated and optimised. Under optimal conditions, the tetracycline removal efficiency reached 64.71%. The adsorption kinetics followed the first-order model, and the adsorption process was in accordance with the Freundlich isotherm model.

Extraction and in vitro antioxidant activity of polysaccharides from Rubus cochinchinensis

2025-08-28T02:05:04+07:00

Rubus cochinchinensis Tratt. is a traditional medicinal plant in Vietnam and has long been used in folk medicine to treat rheumatism, hematoma, hepatitis, and jaundice. However, studies on this plant’s antioxidant activity and polysaccharide extraction procedures remain limited. This study aims to determine the optimal conditions for polysaccharide extraction from R. cochinchinensis and evaluate its antioxidant potential. The optimal extraction conditions were found to be as follows: a temperature of 100 °C, an extraction time of 3 hours, water as the extraction solvent at a solvent-to-material ratio of 50:1 (v/w), three extraction cycles, and an ethanol-to-extract ratio of 4:1 (v/v) for polysaccharide precipitation. The structural characterisation of the extracted polysaccharides was conducted by using Fourier-transform infrared spectroscopy (FT-IR) and gel permeation chromatography. The polysaccharides exhibited an average molecular weight of approximately 510.87 kDa, with a polydispersity index (Mw/Mn) of 27.66. FT-IR analysis revealed characteristic absorption bands corresponding to glucose and galactose residues. In vitro antioxidant assays demonstrated significant activity, with a total antioxidant capacity reaching 0.2793 ± 0.0019 mg GAE/g or 0.1811 ± 0.0009 mg ASE/g. The IC₅₀ values for DPPH and ABTS radical scavenging were 0.87 mg/mL and 3.26 mg/mL, respectively. These findings suggest that polysaccharides extracted from R. cochinchinensis possess promising antioxidant properties and warrant further investigation for potential applications.

Chemical composition, enantiomeric distribution and larvicidal activity against Aedes aegypti and Aedes albopictus of Piper chaudocanum C. DC. essential oil

2026-06-11T14:20:54+07:00

The essential oil of Piper chaudocanum C. DC. was obtained with a yield of 0.15% (w/w). Identified constituents accounted for 96.0% of the total oil composition, with caryophyllene oxide (28.2%), β-pinene (13.8%), and α-pinene (10.6%) as the major components. Chiral GC-MS analysis, reported for the first time for P. chaudocanum essential oil, revealed that (–)-α-pinene (92.1%), (–)-β-pinene (93.1%), and (–)-limonene (80.2%) were the predominant enantiomers. The essential oil exhibited significant larvicidal activity against Aedes aegypti and Aedes albopictus, with 24-h LC₅₀ values of 37.58 and 38.50 µg/mL, respectively.

Synthesis of CuxS/Ni-MOF/NF composite material for hydrogen evolution reaction

2026-01-27T07:01:21+07:00

In this study, Cu_xS was successfully dispersed on the Ni-MOF/NF substrate via the potentiostatic electrodeposition method. The obtained composite material was characterised with X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The Cu_xS/Ni-MOF/NF composites were employed as catalysts for the hydrogen evolution reaction (HER) in alkaline solutions. Compared with the single Cu_xS/NF and Ni-MOF/NF materials, the Cu_xS/Ni-MOF/NF composite exhibited significantly higher catalytic activity for HER. The influence of synthesis conditions of Cu_xS/Ni-MOF/NF on its catalytic activity was studied. Experimental results show that the Cu_xS/Ni-MOF/NF materials synthesised by potentiostatic electrodeposition at E (vs. Ag/AgCl) = –1 V for 30 min in 0.02 M CuSO₄ + 0.06 M thiourea solution demonstrated high catalytic activity for the HER with a low overpotential of 130 mV at 10 mA/cm² in an alkaline electrolyte. In addition, the Cu_xS/Ni-MOF/NF catalyst exhibited excellent catalytic durability and stability, as evidenced by its stable catalytic performance after 20 h of operation.

Taxonomic identification and chlorophyll content variation of dominant green macroalgae belonging to genus Ulva in Huong Phong area, Tam Giang Lagoon, Hue City

2026-06-01T09:22:37+07:00

Species of the genus Ulva are widely distributed worldwide, play an important role in aquatic ecosystems, and have high potential for applications in various fields; however, they can also cause “green tide” events under nutrient-enriched conditions. This study aimed to identify the dominant Ulva species in aquaculture ponds in Huong Phong, Tam Giang Lagoon, and to investigate temporal variation in chlorophyll a and b contents. The samples were collected from March to September 2025 and identified by using a combination of morphological characteristics and two molecular markers, tufA and rbcL. The DNA sequence analysis revealed that the samples exhibited 99–100% similarity to Ulva limnetica and clustered within the same clade in the phylogenetic trees based on both markers. Morphological characteristics were also consistent with the descriptions of this species. The chlorophyll a and b contents showed significant seasonal variation (p < 0.05). The chlorophyll a and b content ranged from 0.23 to 1.20 and 0.20 to 0.61 mg·gww⁻¹, respectively, from March to September, except for a sharp decline in June to 0.01 mg·gww⁻¹ for both pigments (p < 0.05). These findings provide a scientific basis for the occurrence of Ulva limnetica in Tam Giang Lagoon, contributing to the prediction and control of green tide events and supporting the sustainable utilisation and potential applications of this species in the future.

A V/UiO-66 metal-organic framework-modified glassy carbon electrode for electrochemical determination of ethambutol

2026-06-04T13:36:41+07:00

A sensitive electrochemical sensor based on a vanadium-incorporated UiO-66 metal-organic framework-modified glassy carbon electrode (V/UiO-66/GCE) was developed for determining ethambutol in pharmaceutical formulations. The V/UiO-66 material was synthesised via a hydrothermal method and comprehensively characterised with X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy with elemental mapping. Under optimal conditions, the V/UiO-66/GCE exhibited a well-defined oxidation peak, enabling the quantification of ethambutol with a limit of detection of 0.81 μmol.L⁻¹. The proposed method was successfully applied to the analysis of commercial tablets, yielding an acceptable recovery of 95.50%. These results indicate that the V/UiO-66/GCE provides a simple, reliable, and efficient electrochemical approach for the determination of ethambutol.

Optimisation of polyphenol extraction from An xoa stems (Helicteres Hirsuta Lour.)

2026-06-11T12:14:01+07:00

This study optimised the extraction process of polyphenols from the stems of Helicteres hirsuta Lour. with the Response Surface method. Key factors affecting the extraction efficiency, namely ethanol concentration, solvent-to-material ratio, temperature, and extraction time, were investigated through single-factor experiments and a Box-Behnken design. The results indicate that the total polyphenol content (TPC) was significantly influenced by ethanol concentration, temperature, and especially extraction time. A quadratic regression model was developed and found to be statistically significant (p < 0.0001) with good predictive ability (adjusted R² = 0.9357). The optimal conditions were determined as 76.10% ethanol, a 19.36 mL/g solvent-to-material ratio, an extraction temperature of 62.28 °C, and an extraction time of 89.50 minutes, yielding a predicted TPC of 45.10 mg GAE/g extract. The experimental validation showed good agreement with the predicted values, confirming the reliability of the model. This study highlights the potential of H. hirsuta stems as a valuable source of polyphenols for pharmaceutical and functional food applications.

Antifungal activity of Piper betle L. leaf essential oil against Botrytis cinerea and the application of a biodegradable starch-based coating system for strawberry preservation

2026-06-11T11:59:59+07:00

This study was conducted to evaluate the antifungal efficacy of Betel leaf essential oil against Botrytis cinerea and to investigate its potential application in postharvest preservation of strawberries through starch-based edible coatings enriched with essential oil. The results demonstrated that Betel leaf essential oil exhibited pronounced antifungal activity, as evidenced by an inhibition zone diameter of 20.0 ± 1.8 mm, a minimum inhibitory concentration of 1/8% and a minimum fungicidal concentration of 0.5%. In the preservation experiments, strawberries were coated with the starch-based films containing essential oil at concentrations of 0, 0.5, 1.0, and 1.5% and stored at ambient temperature for 8 days. By day 8, the treatments containing 1.0 and 1.5% essential oil showed significantly lower mould incidence than the control (7.1 and 6.4 vs. 46.5%), a weight loss reduction to 11.23 and 10.27% (control 17.61%), while fruit firmness and total soluble solids were maintained at 13.85–14.23 N and 10.01–10.31%, respectively. The findings revealed that the bioactive starch-based coat containing 1.0–1.5% essential oil established a dual-barrier preservation system, effectively suppressing mould development and therefore providing better preservation than the control and the starch-based coat without essential oil. In terms of microbiological, physicochemical, sensory, and surface quality attributes, the starch-based film containing 1.0% Betel leaf essential oil represented the optimal formulation for comprehensive postharvest preservation of strawberries.

Effect of sintering temperature on structure, microstructure and some physical properties of Pb(Zr0.52Ti0.48)0.970Nb0.024Sb0.006O₃ piezoelectric ceramics

2026-04-15T15:43:50+07:00

Pb(Zr_0.52Ti_0.48)_0.970Nb_0.024Sb_0.006O₃ (PZTNS) piezoelectric ceramics were fabricated with the conventional solid-state reaction method. In this paper, the effects of sintering temperatures on the structure, microstructure, and physical properties of PZTNS ceramics were investigated. Crystal structure and microstructure were analysed by means of X-ray diffraction and scanning electron microscopy. Dielectric and piezoelectric properties were measured with a Hioki 3532 RLC meter and an HP 4193A impedance analyser, while ferroelectric properties were characterised with the Sawyer-Tower method. The ceramics were sintered at 1050, 1100, 1150, and 1200 °C for 2 h. The results show that all samples exhibited a typical perovskite structure. At the optimal sintering temperature of 1100 °C and sintering time of 2 h, the ceramics displayed a relatively uniform microstructure with densely packed grains and achieved optimal properties: a density of 7.82 g/cm³, a piezoelectric coefficient d₃₃ of 508 pC/N, electromechanical coupling factors k_p and k_t of 0.64 and 0.53, respectively, and a mechanical quality factor Q_m of 85. With these characteristic parameters, PZTNS ceramics are promising candidates for future ultrasonic and hydroacoustic device applications.