https://jst.vn/index.php/etsd/issue/feed 2025-07-15T09:21:50+00:00 Open Journal Systems https://jst.vn/index.php/etsd/article/view/966 2025-07-15T09:03:31+00:00 Hai Van Nguyen Ba Thu Uyen Nguyen Hung Tien Luong Xuan Bach Cao Tien Cuong Nguyen cuong.nguyentien1@hust.edu.vn

Germinated brown rice has a higher nutritional value than brown rice due to the germination process, which enhances nutrient content. However, this product is easily contaminated by mold during germination, leading to food safety concerns. The aims of this study were to evaluate the antifungal ability of Lactobacillus plantarum NCDN4 lactic acid bacteria against Aspergillus niger CBS 76997 during the germination of brown rice. The in vitro antifungal activity of L. plantarum NCDN4 was assessed in agar and liquid medium. The effect of the bacterial cell-free supernatant and/or biomass on the growth of A. niger was determined based on the mycelial growth diameter of fungi over time. The research results indicated that the mycelial diameter of A. niger treated with L. plantarum ranged from 15-30 mm, lower than the control sample (85mm) after five days of incubation. L. plantarum also delayed the formation of fungi spores. The preliminary results showed that the antifungal mechanism of L. plantarum related to the lactic acid produced during bacteria metabolism, delayed and reduced spore formation, nutrient competition and damaged mycelium of A. niger. L. plantarum reduced the mould contamination rate during the germination of brown rice without affecting the germination of rice, with a germination ability of 94.7%. The mould contamination rates in the samples non-treated and treated with LAB were 100.0% and 15.7%, respectively. The results demonstrated the potential application of L. plantarum in food technology as a biocontrol agent in inhibiting fungi.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/967 2025-07-15T09:09:00+00:00 Van Hieu Vu Anh Tuan Nguyen Quang Vinh Le Xuan Tuan Le Thi Thu Hang Tran hang.tranthithu@hust.edu.vn

Drying is an area that consumes a lot of energy and degrades the nutritional components of dried products if the right drying mode is not chosen. The drying process in different drying agent environments is being studied to find the right drying mode to increase product quality, reduce drying time, and reduce energy consumption. In this study, the drying processes of common agricultural products, namely pear slice and mango slice are conducted in a lab-scale dryer using hot air and superheated steam. Experimental calculation models are established, and product quality will be studied in several aspects including color change and shrinkage to comprehensively evaluate the applicability and suitable drying conditions for pears. The empirical models are built based on the Newton model which give the good agreement results in compared with the experimental model. For both fruit kinds, color of products obtained from superheated steam drying is darker than that from hot air-drying exception of at 110 oC while the porosity of dried product in superheated steam is higher than dried product in hot air. The research results are the basis for expanding the application ability of modulated gas and superheated steam for post-harvest processing technology.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/968 2025-07-15T09:10:46+00:00 Thu Ha Tran Quoc Tuan Hoang Ngoc Hung Pham Quoc Dat Lại Hoang Dung Nguyen Thi To Quynh Cung quynh.cungthito@hust.edu.vn

This study aims to evaluate several physicochemical indicators of black pepper samples purchased from three growing regions: Quang Tri, Ba Ria-Vung Tau, and Dak Lak. The results of ANOVA analysis at a equal 0.05 reveals significant differences in moisture content, total ash content, piperine content, and essential oil content among the pepper samples from these three regions. The results obtained by Principal Component Analysis (PCA) identify the characteristic physicochemical indicators for Dak Lak pepper samples as moisture content, piperine content, and essential oil content. In contrast, Quang Tri pepper samples are characterized by moisture, total ash, piperine, and essential oil content. These findings not only demonstrate a correlation between the physicochemical index of black pepper and the factors associated with its growing regions, but also highlight their practical implications for the cultivation and quality control of black pepper across different regions.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/969 2025-07-15T09:13:25+00:00 Thi Viet Thanh Nguyen thanh.nguyenthiviet@hust.edu.vn Tien Thang Nguyen

Gnetum montanum Markgr. belongs to the Gnetaceae family. Gnetum montanum Markgr. is distributed in the northern mountainous parts of Vietnam and is used as a Vietnamese herbal medicine for the treatment of rheumatoid arthritis, muscular strain and malaria. Previous phytochemical investigations on Gnetum plants have revealed an abundance of flavonoids and stilbenoids. With the goal of isolating compounds from this species in Vietnam, in the continous phytochemical investigation of stem of Gnetum montanum Markgr., we used extraction methods with increasing polar solvents and modern chromatography methods such as thin-layer chromatography (TLC), column chromatography (CC), and high-performance liquid chromatography (HPLC). They were two dimeric stilbenes gneafricanin F (1), gnetuhainin Q (2) together with a stilbene 2,3', 5'-trihydoxy-trans-stilbene (3) and a flavonoid homoeriodictyol (4). Their structures were elucidated by ESI-MS, 1D-NMR, and 2D-NMR combined with comparison with published spectral data.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/970 2025-07-15T09:17:14+00:00 Hoai Nam Truong Thi Hoa Huyen Doan Thi Thu Hang Nguyen Vo Hong Ngoc Nguyen Huy Trong Tran Kim Thanh Do Huu Tuan Minh Nguyen Quynh Nhu Vu Thi Luyen Tran Quang Tung Tran Thi Thuy Tran thuy.tranthi3@hust.edu.vn

The study aims to evaluate the cross-linking ability of Poly(Vinyl Alcohol) (PVA) membranes with L-glutamic acid through solid-phase esterification reactions to improve water resistance. The cross-linked material exhibits enhanced Pb(II) ion adsorption capacity due to porosity introduced by Poly(Ethylene Glycol) (PEG), which increases surface area and swelling ability. The cross-linking reaction and porosity of the material were demonstrated by the crosslink density of the membrane and the material’s swelling behavior in water. Results show that at 130 °C for 60 minutes, the optimal material was obtained, with a crosslink density of 92.89%. After the addition of PEG, water swelling increased to 131.77%, a 51% increase compared to the system containing only PVA and L-glutamic acid. The PVA-c-glu/PEG membrane exhibited excellent Pb(II) adsorption capacity, with a Qe of 66.29 mg/g at room temperature (30 °C), an initial Pb(II) concentration of 114.08 mg/L, pH 7, and a material mass of 0.05 g in 2 days, compared to untreated PVA, which had a Qe of 11.79 mg/g.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/971 2025-07-15T09:18:20+00:00 Thi Thuong Nghiem Thi Ha Anh Bui Trung Nghia Phan Viet Hung Dang hung.dangviet@hust.edu.vn

In the present work, a preparation of insulating materials based on polyethylene/natural rubber/nanosilica (PE/NR/nanosilica) blend was investigated. The optimal condition and composition for the blends were determined including types of natural rubber (i.e, RSS, SVR3L and deproteinized natural rubber-DPNR), type of nanosilica (silica_M with specific surface area of 340-420 m2 /g and silica_255G with specific surface area 285 m2 /g), blending methods and conditions. The mechanical properties, electrical insulation properties and thermal stability of the blends were characterized by tensile test, dielectric strength and thermal gravimetric analysis for each condition. It was found that the mass ratios of PE (L21 type) and NR of 20/80 and a silica content of 4% will result in a good mechanical and dielectric strength, which was 13.2 MPa and 100 kV/mm, respectively. RSS type and silica_M showed good compatibility with L21 in the blend at optimal conditions for the blend preparation. This result was further approved by SEM analysis and FTIR spectroscopy. The blend sample, L21/RSS@silica_M was exhibited better thermal stability and dielectric strength than L21/SVR3L@silica_M and L21/DPNR@silica_M samples and it demonstrated that L21/RSS@silica_M blend samples may be appropriate for electrical insulation application.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/972 2025-07-15T09:19:43+00:00 Van Cuong Tran trancuong.hhvl@gmail.com Duc Ha Ninh Quoc Khanh Dang

Advanced SiAlON ceramics play a crucial role in high-temperature industries, such as aluminum smelting, due to their superior properties, including high thermal stability, excellent thermal shock resistance, and anticorrosive behavior. In the study, Al₂O₃-Y₂O₃-SiO₂ frits (2A4Y3S and 2A5Y2S) were synthesized via sintering, and the dynamic phase formation of these materials was investigated. To lower the sintering temperature, Y₂O₃ and Al₂O₃ particles were synthesized using a co-precipitation method, employing Al(NO₃)₃·9H₂O and Y(NO₃)₃·6H₂O in an NH₄OH solution. Meanwhile, SiO₂ was prepared via the sol-gel method using Na₂SiO₃ as the precursor and HCl as a catalyst. The effects of synthesis conditions on the formation of 2A4Y3S and 2A5Y2S frits via sintering were systematically analyzed using X-ray diffraction (XRD), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The optimal synthesis conditions for 2A4Y3S were achieved by melting at 1200 °C for 5 hours. At 1000 °C, 2A4Y3S exhibited a fully amorphous structure, with crystallization occurring in the temperature range of 1100 °C to 1200 °C. In contrast, the optimal synthesis conditions for 2A5Y2S were obtained by melting at 1300 °C for 5 hours. This material remained fully amorphous at 1100 °C, with crystallization occurring between 1200 °C and 1300 °C. Notably, the crystallization temperatures observed in this study were significantly lower than those required for conventional solid-state reaction methods used in the preparation of advanced ceramics.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development https://jst.vn/index.php/etsd/article/view/973 2025-07-15T09:21:50+00:00 Hai Vu Pham vuhp@vne.edu.vn Thi Thao Nguyen Khanh Huyen Phan Thu Trang Duong Xuan Bach Ngo

Food loss and waste (FLW) is a pressing issue in many countries. In developed countries, school FLW has received much attention, because it is directly linked to children’s nutrition. But in low-and middle-income countries, FLW has not been considered as a priority yet. In Vietnam, there are no statistics on the issue. In the paper, we present an empirical study which investigates and measures FLW from school meals in urban Hanoi. Loss and waste are understood as portions of distributed food, discarded or unconsumed during school lunches. Surveys have been conducted at 8 school kitchens over a total period of 8 weeks. At each kitchen, the team recorded and measured parameters of food distributions and FLW at different stages. Participants to the study are children at primary and secondary schools, randomly selected by classes from grades 1 to 9. In terms of findings, the FLW quantity is estimated at 118 grams of food per individual at lunch on average, equivalent to 29% of the total cooked and served food-equivalence (excluding added water and/or species). Vegetables had the highest wastage rate, while that of meat was the lowest. We also found that FLW rate is sensitive to whether children are in primary or secondary school, to age, and to the menu’s composition. By developing a protocol of FLW collect and analysis in Hanoi, adapted for Vietnam food, we produced for the first time in Vietnam a dataset and values, which are the basis for policy recommendations.

Copyright (c) 2025 JST: Engineering And Technology For Sustainable Development