bluuebunny/crossref_metadata_2025 huggingface dataset:
SURVEY OF THE EFFECTS OF NEEM LEAF EXTRACT ON THE WATER QUALITY AND PHYTOPLANKTON COMMUNITY IN FRESHWATER CATFISH POND IN BINH DUONG PROVINCE
Authors: Binh Nguyen Thanh
Published: April 2018

In Vietnam, the total area of freshwater catfish pond reached 1959 hectares in 2015 to satisfy the national and international markets. The use of synthetic chemicals in fish farms has threatened the environmental ecology and also fish quality so it is really necessary to carry out researches on alternative compounds from plants. The extract of neem Azadirachta indica has been widely applied as an environmental insecticide, especially in fish pond to control fish diseases and parasites in several countries around the world. However, there has not been widely applied in Vietnam. In this study, the effects of neem leaf extract on the water quality and phytoplankton community in freshwater catfish pond in Binh Duong province was investigated. It was shown that at a concentration of 90 mg / L, the extracted from neem leaf have a positive impact on water quality; reduce the concentration of parameters such as COD, N-NO3-, P-PO43-, SD, and SS value. pH value of water was not affected by adding extract at this concentration. In case of plankton community, the result indicated that slightly change in occurrence frequency of phytoplankton community in water was noticed and no change in phytoplankton species composition such as Anisonema sp., Euglena acus, Phacus pleuronectes, Trachelomonas armata and Trachelomonas, which means neem leaf extract might be an environmental friendly to be used in Pangasius hypophthalmus fish pond.
ACCUMULATION OF FLAVONOIDS IN SOYBEAN UNDER EFFECTS OF CYANOBACTERIAL CRUDE EXTRACT AND APHID INFESTATION
Authors: Chung Mai Van
Published: April 2018

The differential accumulation of endogenous flavonoids was recorded in soybean (G. max(L.) Merr. cv. “Nam Dan”) under infestation of cowpea aphid (Aphis craccivora Koch) and/ortreatment of the crude extract of cyanobacterium strain Nostoc calcicola HN9-1a. During A.craccivora infestation, flavonoids in the aphid-infested leaves were strongly induced to highcontents, which were 1.84–2.21 - fold higher than that observed in control. Those bioactivesubstances were suppressed by the single treatment of N. calcicola crude extract, however, wereenhanced by the cross-talk interactions of N. calcicola HN9-1a and A. craccivora. Flavonoids inthe double factors-effected soybean leaves were remarkably increased to high level since 24hours after cowpea aphid attack, having by 2.99 - 3.06-fold higher than that in control. It was theimportant evidences to suggest that flavonoids may function in the defense mechanism ofsoybean “Nam Dan” against A. craccivora; and N. cacicola HN9-1a crude extract improved theaccumulation of flavonoids in soybean response to cowpea aphid infestation.
CHEMICAL CONSTITUENTS FROM ETHYL ACETATE EXTRACT OF SCOPARIA DULCIS LINN.
Authors: Lien Huong Ton Nu
Published: April 2018

This research focuses on the isolation and characterization of eight natural compounds fromthe ethyl acetate extract of Scoparia dulcis L. collected in An Giang province, Vietnam. Sixflavonoid compounds: apigenin (1), luteolin (2), baicalein (3), oroxylin A (4), oroxylin A 7-O-β-D-glucoside (5) and vitexin (6) along with two nitrogen-containing compounds: 2,4-dihydroxy-1,4-benzoxazin-3-one (7) and uracil (8) were successfully isolated via the methods of naturalproduct extraction. The structures of these compounds were elucidated base on 1D-NMR and2D-NMR spectral data as well as MS and compared with those in the authentic reports. Thisstudy contributed new results to the phytochemical examination of Scoparia dulcis Linn.growing in Vietnam with the presence of the first isolated compounds as (3), (4), (5), (7) and (8).
SELECTIVE AND EFFICIENT OXIDATION OF UNSATURATED ALCOHOLS AS CONSTITUENTS IN ESSENTIAL OILS
Authors: Xuan Thi Luu Thi
Published: April 2018

Essential oil unsaturated alcohols have been oxidized efficiently into the correspondingunsaturated aldehydes by potassium permanganate supported copper(II) sulfate pentahydrate.Unsaturated aldehydes such as geranial and cinnamaldehyde being valuable components in food,cosmetic, perfumery and pharmaceutical chemistry, have been obtained in good yields (> 60%)under two activation methods: microwave irradiation and conventional heating.
PREPARATION OF POLYMER COMPOSITES BASED ON UNSATURATED POLYESTER REINFORCED BY NATURAL FIBER AND CELLULOSE MICROFIBER FROM LUNG WASTE IN NGHE AN
Authors: Cuong Cao Xuan
Published: April 2018

Unsaturated polyester composites reinforced by glass fiber and by hybrid reinforcementglass fiber - lung fiber with cellulose microfiber (MFC) were prepared and investigated. Tensileand flexural strengths of material reached the highest value at polymer composite with 48 %wglass fiber mat and 0.3 %w MFC (208.33 MPa and 243.6 0 MPa), while the highest impactstrength reached 212.48 kJ/m2 at composite containing 48 %w glass fiber but 0.5 %w MFC.Especially, with 0.3 %w MFC, the tensile fatigue cycle to failure of composite processed byvacuum bag remarkably increased, 140.28 % at composite with 48 %w glass fiber and 265.63 %at hybrid composite reinforced by glass fiber/lung fiber, compared to samples without MFC.
ẢNH HƯỞNG CỦA MỘT SỐ ĐIỀU KIỆN ĐẾN QUÁ TRÌNH BIẾN TÍNH TẢO SPIRULINA
Authors: Chiên Trương Thị
Published: April 2018

Bài báo này trình bày nghiên cứu về ảnh hưởng của một số điều kiện đến quá trình biếntính tảo Spirulina. Trong nghiên cứu này, chúng tôi đã sử dụng phương pháp vật lí để phá vỡmàng tế bào tảo Spirulina. Sinh khối tảo được lạnh đông ở -15 ºC trong 3 giờ với hàm lượngprotein hòa tan đạt 60,86 %, hiệu suất phá vỡ màng tế bào đạt 94,75 %. Sau đó hỗn hợp tảoSpirulina được xử lí ở nhiệt độ 70 ºC trong 5 - 10 phút để biến tính phycobiliprotein. Cuối cùngtảo biến tính được đông khô ở -49 ºC với áp suất 50 mmTorr. Sản phẩm thu được có màu xanhtự nhiên, mùi dễ chịu, bột tơi xốp và chất lượng giảm không đáng kể so với bột nguyên liệu banđầu.
INITIAL RESEARCH ON CHEMICAL CONSTITUENTS OF CURCUMA SINGULARIS RHIZOMES
Authors: Cuong Nguyen Manh
Published: April 2018

From the rhizomes of Curcuma singularis Gagnep (Zingiberaceae family), six compounds,including three terpenoids, p-menthane-1,2,4-triol (1), amoxantin A (2), rugosic acid B (3); twodiols, 2,3-butanediol (4) [2R,3R-butanediol (4a) and 2S,3S-butanediol (4b)], and meso-2,3-butanediol (5), along with 3-hydroxy-4-methoxy benzoic acid (6) were isolated. All of sixcompounds were obtained for the first time from the Curcuma genus. The structures of thosecompounds were determined by 1D and 2D-NMR spectroscopic data.
BƯỚC ĐẦU THU NHẬN R-PHYCOERYTHRIN TỪ RONG NƯỚC LỢ CHEATOMORPHA SP. ĐỒNG BẰNG SÔNG CỬU LONG
Authors: Ngọc Nhơn Hoàng Thị
Published: April 2018

R-phycoerythrin (R-PE) là một chất màu huỳnh quang đỏ thuộc họ phycobiliprotein, có rấtnhiều ứng dụng quan trọng trong các ngành công nghiệp thực phẩm, chẩn đoán miễn dịch, mỹphẩm, đánh dấu protein và tế bào, phân tích, trị liệu. Đây là sắc tố có mặt chủ yếu trong các loạitảo đỏ, cũng có thể tìm thấy trong một số loại tảo lục. Với mục đích bước đầu thu nhận R-PE từrong Cheatomorpha sp. ở khu vực đồng bằng sông Cửu Long (ĐBSCL), nghiên cứu này đã thựchiện quá trình trích li R-PE với sự xúc tác của enzyme cellulase (nồng độ enzyme 125 UI/g,nồng độ cơ chất 10 %) trong thời gian 3 giờ, nhiệt độ phòng. Tiến hành tủa với các dung môihữu cơ như cồn, giấm gạo, acetone, acid acetic ở các nồng độ và tỉ lệ khác nhau. Tác nhân tủa làacid acetic 50 % cho kết quả về lượng và độ tinh khiết của chế phẩm R-PE là cao nhất, tiếp theolà (NH4)2SO4 60 %.
SYNTHESIS OF BIOTINYLATED FERROCENE, AND ITS APPLICATION AS A REDOX PROBE FOR ELECTROCHEMICAL IMMUNOSENSOR
Authors: Quynh Anh Le Huu
Published: April 2018

The coupling compound of Biotin (Vitamin H) and redox molecule ferrocene throughcovalent bonding was studied. Synthesis and structure identification of Biotinylated 1 - (- 2-aminoethyl) ferrocene were performed by 1H-NMR, 13C-NMR and MS. The ultimate goal of thispaper is to develop derivatives of ferroceneservingas an electrochemical probe that wouldenhance the performance of immunosensor.An immunosensor based on polypyrrole-streptavidinlayer as platform for immobilization of biotinylatedferrocene and antibodies was developed. Themeasurement of redox signal of ferrocene was analyzed by differential pulse voltammetry(DPV) method and underlined a variation of redox properties upon the antigen interaction. Theintroduction of the redox biotinylatedferrocene into streptavidin-polypyrrole layer affords a goodsensitivity of the biosensor with a detection limit of 0.16 pg.mL-1.
RELATIONSHIP BETWEEN BITTERNESS OF BREWER’S YEAST HYDROLYSATE AND HYDROPHOBIC AMINO ACID CONTENT
Authors: Thanh Ngoc Nguyen Thi
Published: April 2018

Brewer’s yeast spent, obtained after the main fermentation stage, is a rich- in-protein source(protein content accounts for 48 - 50 % dry matter). In order to use efficiently this source, it washydrolysed by different methods. Protein hydrolysate products are normally mixtures of peptidesand amino acids. Protein hydrolysates have a wide range of applications in food. It can be usedas emulsifying agents in a number of applications such as salad dressings, spreads, ice cream,coffee whitener, cracker, and meat products like sausages. However, bitterness in hydrolysates isone of the major undesirable aspects for various applications in food processing. In this study,we used enzymatic mixture alcalase and flavourzyme, yeast treatment methods to hydrolysebrewer’s yeast. The hydrolysate and fractions of protein hydrolysate obtained after filtration with10 kDa and 3 kDa filters were used for determination of bitterness and hydrophobic amino acidscontent. The bitter taste of hydrolysate was determined by sensory method (using quininestandard) and amino acid content was analysed by HPLC method. The result showed the closerelationship between bitter taste and hydrophobic amino acid content. The bitter taste of proteinhydrolysate was reduced as the hydrophobic amino acid content decreased. When the bitter taste(equivalent to quinine concentration) decreased from 16.25 μmol/l to 3.59 μmol/l, the totalcontent of hydrophobic amino acids in protein hydrolysate reduced from 1653 μg/ml to 932μg/ml.
SECONDARY METABOLITES PRODUCED BY MARINE BACTERIRUM MICROMONOSPORA SP. (G068)
Authors: Tuan Cao Duc
Published: April 2018

Nine compounds (1-9) were isolated and characterized from the culture broth of the marinebacteria Micromonospora sp. (strain G068), which was isolated from sediment collected at CoTo – Quang Ninh. Their structures were determined by spectroscopic analysis including MS, 1DNMR and 2D NMR, as well as by comparison with reported data in the literature. Allcompounds were evaluated for their antimicrobial activities against a panel of clinicallysignificant microorganisms. Compounds 1, 6, and 9 selectively inhibited Escherichia coli withMIC values of 128, 128 and 64 μg/mL, respectively.
INVESTIGATION OF INENZYME TREATMENTS TO ASSIST EXTRACTION OF ESSENTIAL OIL FROM THE LEAVES AND BRANCHES OF CINNAMOMUM CASSIA COLLECTED IN YEN BAI PROVINCE
Authors: Bich Hoang Thi
Published: April 2018

In order to improve the efficiency of essential oil distillation of the leaves and branchesfrom the cassia plant (Cinnamomum cassia (L.) J. Presl) growing in Yen Bai province, theeffects of enzyme treatments of the plant materials before distillation were investigated usingcrude laccase obtained from culture medium of the fungus Ganoderma lucidum and Cellic Htech2 (Novozymes, Denmark), a multienzyme system consisting of cellulase and xylanase. Theresults showed that enzyme treatments increased oil yield and shorten distillation time. The useof a mixture of both enzyme systems was more effective than using them separately. Underoptimal conditions, an increase in oil yield of 41.7 % was achieved, while distillation time wasshortened from 8 to 5 hours. The enzyme treatments did not change the qualitative compositionof the essential oils. However, significant changes in the percentages of cinnamic aldehyde(69.74 % to 85.6 %) and cinnamyl acetate (17.2 % to 1.34 %) were observed.
RESEARCH OF CHEMICAL COMPONENTS OF SOME SEAWEED SPECIES IN CON CO ISLAND – QUANG TRI PROVINCE
Authors: Thanh Le Tat
Published: April 2018

11 samples of 8 seaweed families were collected at Con Co – Quang Tri and determined ofthe chemical compositions. The analysis results showed that these seaweed samples in Con Cocontain high content of trace elements and low content of heavy metals. Many samples havegood lipid quality to meet the requirements of safe food, as well as being good for the humanhealth (such as CC1, N9, N4, and N6 samples). Especially, some seaweed samples were foundto contain long-chain fatty acids with many double bonds presenting high bioactivity in theirlipid composition, such as C20: 4n-6 (AA) up to 22.35% (Hypnea flagelliformis Grev., sampleN6), C20: 5n-3 (EPA) 16.36 % (Grateloupia lithophila, sample N9), C22: 6n-3 (DHA) 1.07 %(Hypnea esperi, sample N2), C22: 5n-3 (DPA) 1.82% (Liagora spl., samples N4).
SYNTHESIS AND CYTOTOXIC ACTIVITY EVALUATION OF NOVEL DERIVATIVES OF MURRAYAFOLINE A
Authors: Anh Le Duc
Published: April 2018

Two new conjugates of murrayafoline A with zerumbone and artemisinin 3, 11 wereprepared by N-alkylation, in which, compound 3 was synthesized from two consecutive Nalkylationreactions. Their cytotoxicity was evaluated on four human cancer cell lines Hep-G2,LU, RD and Fl. The result showed that both compounds exhibited no activity against the testedcell lines.
PTP1B INHIBITORY CONSISTUENTS FROM VIETNAMESE MEDICINAL PLANT SELAGINELLA TAMARISCINA
Authors: Hung Nguyen Phi
Published: April 2018

Inhibitors of protein tyrosine phosphatase 1B (PTP1B) are promising agents for thetreatment of type 2 diabetes and obesity. From the alcoholic extract of the aerial parts ofSelaginella tamariscina, four compounds including selaginellin (1), amentoflavone (2), β-sitosterol (3), and scoparone (4) have been isolated and structurally elucidated by usingcombined chromatographic and spectroscopic experiments. Among the isolates, selaginellin (1)and amentoflavone (2), exhibited potential PTP1B inhibitory activities with IC50 values of 15.9 ±0.6 and 7.4 ± 0.5 μM, respectively.
CONTRIBUTION TO RESULTS OF THE CHEMICAL CONSTITUENTS OF RICINUS COMMUNIS
Authors: Hoai Van Tran Thi
Published: April 2018

Using combined chromatographic methods, four compounds were isolated from the nhexaneand ethyl acetate extracts of the Ricinus communis in Melinh - Hanoi. Their structureswere determined to be lupeol (1), epialeuritolic acid (2), ergosterol peroxide (3), and ricinine (4)by 1D-, 2D-NMR spectroscopic methods and in comparison with those reported in literature.
MICROENCAPSULATION OF GAC OIL IN CHITOSAN BEAD
Authors: Minh Ngoc Ta Thi
Published: April 2018

Gac oil is a Vietnamese traditional product that contains a high concentration of interestingcarotenoids (beta-carotene and lycopene), which are very useful in cancer treatment and antiagedprotection due to their strong antioxidant activity. However, its hydrophobicity restrains itsuses in food applications which are normally aqueous systems. This problem is possiblyovercome with the help of microencapsulation technology. In this paper, Gac oil wasencapsulated in chitosan beads using dripping method. Gac oil emulsified in chitosan 2 % wasdropped into alkaline solution. The bead’s formation was evaluated through the decrease of beadweight and pH of alkaline solution. Chitosan beads expressed a good protection to Gac oil with acalculated haft-time life of beta-carotene up to 2 years. Encapsulation yield and encapsulationefficiency were also determined.
OFFLOADING LTE DATA TRAFFIC WITH NAMED-DATA NETWORKING INTEGRATION
Authors: Dung Ong Mau
Published: April 2018

Nowadays, mobile Internet becomes increasingly popular and the number of mobile users is growing exponentially. With a traditional clients-server connection, servers are usually in overload state by a huge number of users accessing the service at the same time. Moreover, in a century of “green” Internet technology, it should be more effective in content distribution for a huge number of users. Named-Data Networking (NDN) had been proposed as the promising solution for above problem, which is a content name-oriented approach to disseminate content to edge gateways/routers. In NDN, popular contents are cached at routers for a certain time, and the previously queried one can be reused for multiple times to save bandwidth. In this paper, we propose a solution for Long Term Evolution (LTE) mobile network based on the concept of NDN. By OPNET Modeler simulation, we carry out the evaluation in realistic mobile network with a huge number of mobility LTE mobile stations access to a single server, where content names and content sizes are obtained from real trace of Internet traffic. The obtained results show that Evolved Packet Core (EPC) caching scheme can helps to further increases the quality of service as well as offloads server traffic significantly.
ADAPTIVE-BACKSTEPPING POSITION CONTROL BASED ON RECURRENT-FWNNS FOR MOBILE MANIPULATOR ROBOT
Authors: Long Mai Thang
Published: April 2018

In this paper, we proposed an adaptive-backstepping position control system for mobile manipulator robot (MMR). By applying recurrent fuzzy wavelet neural networks (RFWNNs) in the position-backstepping controller, the unknown-dynamics problems of the MMR control system are relaxed. In addition, an adaptive-robust compensator is proposed to eliminate uncertainties that consist of approximation errors and uncertain disturbances. The design of adaptive-online learning algorithms is obtained by using the Lyapunov stability theorem. The effectiveness of the proposed method is verified by comparative simulation results.
A NOVEL METHOD FOR DESIGNING THE CONTROLLER OF A LCL-FILTER-BASED GRID-CONNECTED INVERTER WITH CONSIDERING VARYING SYSTEM PARAMETERS
Authors: Nhan Nguyen Trung
Published: April 2018

Exactly determining the control coefficients for the controller of a three-phase LCL-filter-based inverter is an important and challenging issue in microgrid systems. However, existing LCL-filter-based inverter systems usually assume that all system parameters are determined accurately and remain constant over time, which is not true in real situations. Variations in the system parameters are known to possibly seriously degrade the performance of LCL-filter-based inverter systems. For efficiency and robustness, this paper proposes a novel method for the generalized controller design of a three-phase LCL-filter-based grid-connected inverter system that can address deviations in system parameters. An optimum way to determine the stability bounds under various system parameters cases is introduced. The assessment of the stability bounds is based on the Routh criterion by solving the characteristic equation of the closed-loop control system. Simulations results are presented to validate the correctness and effectiveness of the proposed design method.
OPTIMAL POWER FLOW WITH TCSC DEVICE USING CUCKOO OPTIMIZATION ALGORITHM
Authors: Long Duong Thanh
Published: April 2018

Optimal Power Flow (OPF) problem is an optimization tool through which secure and economic operating conditions of power system is obtained. In recent years, Flexible AC Transmission System (FACTS) devices, have led to the development of controllers that provide controllability and flexibility for power transmission. Series FACTS devices such as Thyristor controlled series compensators (TCSC), with its ability to directly control the power flow can be very effective to power system security. Thus, integration TCSC in the OPF is one of important current problems and is a suitable method for better utilization of the existing system. This paper is applied Cuckoo Optimization Algorithm (COA) for the solution of the OPF problem of power system equipped with TCSC. The proposed approach has been examined and tested on the IEEE 30-bus system. The results presented in this paper demonstrate the potential of COA algorithm and show its effectiveness for solving the OPF problem with TCSC devices over the other evolutionary optimization techniques.
A FORMULA TO CALCULATE PRUNING THRESHOLD FOR THE PART-OF-SPEECH TAGGING PROBLEM
Authors: Hieu Nguyen Chi
Published: April 2018

The exact tagging of the words in the texts is a very important task in the natural language processing. It can support parsing the text, contribute to the solution of the polysemous word, and help to access a semantic information, etc. One of crucial factors in the POS (Part-of-Speech) tagging approaches based on the statistical method is the processing time. In this paper, we propose an approach to calculate the pruning threshold, which can apply into the Viterbi algorithm of Hidden Markov model for tagging the texts in the natural language processing. Experiment on the 1.000.000 words on the tag of the Wall Street Journal corpus showed that our proposed solution is satisfactory.
GLUCOSE CORRECTION IN HANDHELD DEVICES BY REDUCING THE EFFECT OF HEMATOCRIT
Authors: Hieu Huynh Trung
Published: April 2018

This study presents an approach for glucose correction in handheld devices by reducing the effects of hematocrit. The hematocrit values are estimated from the transduced current curves which are produced during the chemical reactions of glucose measurement process in the handheld devices. The hematocrit estimation is performed by applying the single-hidden layer feedforward neural network which is trained by the non-iterative learning algorithm. The experimental results show that the proposed approach can improve the accuracy of glucose measurement by using the handheld devices.
BIO-BASED SUPERVISORY CONTROL OF A LOWER EXOSKELETON FOR STANCE PHASE
Authors: Toan Tran Huu
Published: April 2018

This paper presents a newly supervisory impedance control strategy of a wearable lower limb exoskeleton in stance phase intended to enhance human performance and support load-carrying using biomechanical analysis. In order to control the coupled human-robot system, the impedance control strategy, previously developed by the authors for swing phase, has been herein expanded up to the stance phase by regulating the desired impedance between the exoskeleton and a wearer's limb according to a specific motion speed. The effect of human behaviours on the change of impedance parameters across variable walking speeds in the stance phase is adopted to design the fuzzy rules for the control strategy. The control performance of the designed exoskeleton is evaluated on a bench-testing over different ranges of walking speeds (about 0.3 m/s to 1.2 m/s). Experimental results show that the resulting interaction torque, the human-exoskeleton tracking error, and electrical power consumption are significantly reduced as compared to a traditional impedance control, especially in the stance phase. Besides that, an average of 72.3 % of the load was transferred to the ground by the exoskeleton during the stance phase of walking. The developed control strategy on the lower exoskeleton has the potential to increase comfort and adaptation to users during daily use.
A STATISTICAL APPROACH FOR PACKER IDENTIFICATION
Authors: Hai Nguyen Minh
Published: April 2018

Most of modern malware are packed by packers which automatically generate a lot of obfuscation techniques to defeat the anti-virus software. To identify packer, most of industry approaches still adopt the well-known technique of signature matching which can be easily evaded. This paper studies the new approach of applying a statistical approach to tackle this problem. We propose a new weight for extracting what obfuscation techniques might be more favourable in packers. We call it obfuscation technique frequency-inverse packer frequency ( ). As the term implies, calculates values for each obfuscation techniques in a packer through an inverse proportion of the frequency of the obfuscation technique in a particular packer to the percentage of packers the obfuscation technique appears in. Obfuscation techniques with high value show a strong relationship with the packer they appear in. Based on this weight, packer is represented by a vector of . Then the used packer is identified by measuring the similarity between vectors of packer and targeted file. For checking the accuracy of our approach, we have performed the experiments of identifying packer on 200 real-world malware for comparing between our approach with the binary signature technique adopted in CFF Explorer. The result shows that our technique produces the better detection.
CHANGES IN VOLATILE COMPOUNDS DURING ORTHODOX BLACK TEA (Camellia sinensis) MANUFACTURING
Authors: Tuan Hoang Quoc
Published: April 2018

The content of volatile compounds in tea leaves at different stages of OTD black tea manufacture was measured. Aroma concentrate was prepared by Brewed Extraction Method (BEM) and analyzed by GC/MS. The results showed that volatile compounds were products of lipid breakdown (groupI) and derivatives from terpenoids, carotenoids and amino acids (group II). During processing the changes of group I and group II were significantly different from each others and effect to the flavour index. A gradual increase of percentage relative content from 16.72 to 18.09 in the group I volatile compounds was noticed during withering. While during fermentation, the sum of group II compounds content was higher than than that of group I compounds therefore the value of flavour index, and the value of FI is higher than 1.
FACTORS AFFECTING THE RECOVERY YIELD AND THE PURITY OF N-ACETYL GLUCOSAMINE FROM CHITIN HYDROLYSATE Dang
Authors: Huong Dang Thi
Published: April 2018

In this study, different ratio of ethanol to hydrolysates obtained by hydrolyzing chitin by chitinase as well as concentration of hydrolysates was investigated to find the optimal value. The result showed that the optimal ratio of absolute ethanol to hydrolysates was 9:1. The further increase of this ratio up to 11:1 resulted only in insignificant increase of N-acetylglucosamine (NAG) recovery yield from 74.47 % to 75.39 % and NAG purity from 93.25 % to 93.44 %. Concentration of hydrolysate also affected the NAG recovery yield and NAG purity. The impurity of crystallization by cooling down the hydrolysates appeared only when hydrolysate was concentrated at a certain level. The mass of crystallization impurity was increased sharply from 0 to 0.082 mg/ml when hydrolysate’s concentration was increased significantly from 1 to 7.9 fold, then slightly from 0.082 to 0.093 mg/ml as its concentration further increased up to 15.7 fold. Higher concentration of hydrolysate resulted in lower recovery yield but purer product. According to HPLC analysis, 93.25 % of NAG purity with recovery yield 74.47% was obtained at optimal ethanol/hydrolysates ratio and optimal concentration of hydrolysate.
OPTIMAL CONDITIONS FOR EXOPOLYSACCHARIDE PRODUCTION BY Lactobacillus plantarum T10
Authors: Khanh Tran Bao
Published: April 2018

Exopolysaccharide (EPS) production ability of Lactobacillus plantarumT10 was studied. The supplement of some sugars (lactose, saccharose, and glucose) gave the positive effects on EPS production of L. plantarum T10, in which the addition of lactose 4 % resulted in the most efficiency for EPS yield (274.83 μg/mL). The addition of 0.4 % of yeast extract into culture medium with 4 % lactose provided the highest EPS yields compared to other nitrogen sources (peptone, beef extract), which were 378.32 mg/mL. The optimal conditions for EPS production of L. plantarum T10 in MRS broth with 4 % of lactose and 0.4 % yeast extract supplement were also studied. The results indicated that the highest EPS yield (417.11 mg/L) was obtained in the conditions of 106 CFU/ml initial cell density, temperature of 35 oC, pH 5.5 and 48 h incubation.
USING CELLULASE TO IMPROVE THE EXTRACTION EFFICIENCY OF THE ANTIOXIDANT COMPOUNDS FROM WHITE RADISH (Raphanus sativus L.) POWDER
Authors: Kim Ngoc Pham Thi
Published: April 2018

White radish (Raphanus sativus L.) is an edible root vegetable of the Brassicaceae family. It is cultivated and consumed all over the world. Nowadays, radishes are used and eaten by many people in their daily meals. Some studies showed that it has a high content of antioxidant compounds. In this study, we used enzyme - assisted extraction (EAE) to produce an antioxidant - rich extract. The antioxidant activity of the extract was determined by the ABTS radical cation scavenging capacity. The optimal extraction conditions of the antioxidant compounds from white radish were: enzyme concentration of 1.75 % (v/w), extraction time of 81 minutes, pH 4.56 and extraction temperature of 48 oC. As a result, the antioxidant activity of the extract was 0.1594 ± 0.033 m Moltrolox equivalent antioxidant capacity (TEAC)/g and 161 % higher than that of the control sample(CE).Furthermore, SEM (scanning electron microscopy) analysis result showed that there was a difference in the surface structure of white radish powder after being extracted by CE and EAE.
STUDY ON THE BIOACTIVITY OF GINGER, GALANGAL EXTRACTS OF DIFFERENT REGIONS IN VIETNAM FOR PRESERVING SEAFOOD
Authors: Tam Phan Thanh
Published: April 2018

Ginger and galangal have long been known as common spices in Vietnam and referred in many reports as antibacterial, anti-inflammatory, well-digestive in traditional medicine. This study assessed the components with biological activities such as antibacterial and antioxidant from ginger, galangal extracts in a number of different regions in the country (Hai Duong, Bac Ninh, Nghe An, Tay Nguyen and Quang Nam).The results showed that the polyphenols components (based on gallic acid) in ginger, galangal extracts in ethanol/water higher than in water: the highest ginger extract in ethanol/water (50 % v/v) of 19.93 mg/g dry matter was Nghe An ginger, the lowest of 17.2 mg/g dry matter was Tay Nguyen ginger. The highest galangal extracts in ethanol/water (60 % v/v) of 11.58 mg/g dry matter was Quang Nam galangalandthelowest of 10.5 mg/g dry matter was Tay Nguyen galangal. The highest extraction in water of 9.27 mg/g dry matter was NgheAnginger, the lowest of 6.6 mg/g dry matter was Tay Nguyen ginger. These extracts werewellanti-bacterialto certain human pathogenic microorganisms,whichare contaminated in food and seafood.The highest antibacterial diameter to V. parahamolyticus ATCC 17802 of the extract in ethanol/ water was 35 mm (Nghe An ginger) and the lowest was 31mm (Tay Nguyen galangal), while for the extracts in water the highest was 33 mm (Nghe An ginger) and the lowest was 25 mm (Tay Nguyen galangal). Antioxidant ability of these extracts was determined by ability of eliminating DDPH free radical, for extracts in ethanol/water, the highest was Bac Ninh galangal with 72.9 %, the lowest was Hai Duong ginger with 62.17 %.Exploiting the components from ginger, galangal with intention to preserve seafood materials, help prolong and ensure safety is very meaningful job, which helps replace the misuse of toxic chemicals as urea, formol, etc., which are currently used widespread, which can severely impact the health of consumers.
RECOVERY OF PECTIC OLIGOSACCHARIDE (POS) FROM PECTIN HYDOLYSATE FOR FUNTIONAL FOODS
Authors: Kim Dung Nguyen Thi
Published: April 2018

Pectic oligosaccharide (POS) obtained bypartial hydrolysis of pectin is proposed as a new class of prebioticwhich has many beneficial propertiesfor the health of humans and animals. Currently only a small number of researcheshave explored the production process of POS products in laboratory-scale and pilot, however the manufacturing process, as well as the product, has not yet been offered for sale on the market. In this study, several parameters of arecovery processofPOS powder from the pectin hydrolysatehave been established: condense(5 times, by tangential filtration with nanofiltration column 0.3 kDa), precipitate (ratio of ethanol / concentrates: 3/1), spray drying (5 % maltodextrin, inlet air temperature 170 oC, liquid flow rate 2.5 L/h). The total yield of the recovery processes is 67.7 %. The POS product is still stable after 12 months of storage in plastic bags and in bags of tin. Food safety analysis indicate that POS products do not contain mycotoxins, heavymetals, pathogenic microorganisms and the lethal dose LD 50 can not be detected.
ĐÁNH GIÁ ẢNH HƯỞNG CỦA CƯỜNG ĐỘ SỤC KHÍ CỦA QUÁ TRÌNH THU HỒI VI TẢO BẰNG KĨ THUẬT LỌC MÀNG
Authors: Uẩn Đỗ Khắc
Published: April 2018

Nghiên cứu này tiến hành áp dụng kĩ thuật lọc màng để thu hoạch vi tảo. Trong quá trình lọc, màng bị tắc do vi tảo bám dính lên bề mặt màng lọc. Kết quả nghiên cứu cho thấy hệ thống sục khí có vai trò quan trọng để hạn chế vi tảo bám lên bề mặt màng. Cường độ sục khí ảnh hưởng lớn đến năng suất lọc và áp suất hút. Cường độ sục khí được xác định tỉ lệ nghịch với diện tích bề mặt được sục khí. Kết quả khảo sát cho thấy khi cường độ sục khí nhỏ hơn 0,189 l/cm2.phút, năng suất lọc giảm và áp suất hút tăng rất nhanh, khi cường độ sục khí lớn hơn 0,189 l/cm2.phút, áp suất hút tăng không đáng kể và ổn định dần. Vì vậy, trong quá trình thiết kế hệ thống cần tính toán hợp lí để diện tích bề mặt bé nhất sao cho cường độ sục khí tối ưu, vừa tiết kiệm năng lượng, vừa giải quyết vấn đề tắc màng hiệu quả nhất.
CHARACTERIZATION OF CELLULASE PREPARATION OF BACILLUS SP.G4 ISOLATED FROM THE TERMITES GUT
Authors: Thanh Xuân Đào Thị
Published: April 2018

The Bacillus sp. strain G4 isolated from termites gut can produce cellulase with high activity in rice bran medium after 72 h of incubation at 37 °C. The crude enzymewas collected by centrifugation at 6,000 rpmfor 15 minutes.  The precipitation of cellulasewith ammonium sulfate 60 – 90 % saturation and acetone at the concentration 60 % – 90 % was studied. Results showed that ammonium sulfate 90 % saturation gave cellulase with highest purification factor 8.87 but the yield was only 59.9 %, whereas acetone at 90 % concentration gave highest yield 83.57 % with purification factor 4.38. CMCase activity of cellulasepreparation obtained by acetone precipitation at 90 % was optimum at pH 7 and 60 °C. Furthermore, CMCase was stable at pH 6.0 - 7.0 and at temperature lower than 50 °C. The CMCase was activated by ion Ca2+ but inhibited by Co2+, Zn2+, Cu2+, Fe2+, and was not affected by Mg2+ and Ba2+. The CMCase was inhibited by high concentration of SDS while EDTA and Tween 80 played activated role.
EFFECT OF ROASTING ON TEXTURE, COLOUR, NUTRIENT CONTENT AND ACCEPTABILITY OF SOYBEANS (GLYCINE MAX)
Authors: Hung Pham Ngoc
Published: April 2018

Effect of roasting on texture, colour, and nutrient content and sensory acceptability of soybean was studied at four temparture (160, 180, 200 and 220 oC) and time (10, 15, 20 and 25 minutes) combinations. In general, hardness and toughness decreased with increased in roasting temperature and time except at 200 and 220 oC for 20 minutes. L* values of roasted soybean decreased at increased temperatures while a* values increased with increasing roasting temperature and time that affected to hue and chroma values of soybean. The highest sensory evaluation including colour, appearance, roasted odour and overall quality were found for soybean roasted at 200 oC for 20 minutes. Lipid and ash content of the roasted soybean was found to have increased following the roasting time and temperature. While the protein content of the soybean roasted decreased as the roasting time and temperature increased.
INFLUENCE OF FACTORS ON THE BITTERNESS AND SENSORY TASTE IN PROTEIN HYDROLYSATE FROM SPENT
Authors: Thanh Ngoc Nguyen Thi
Published: April 2018

Spent brewer’s yeast, obtained after the main fermentation stage, is a rich- in-protein source (protein content accounts for 48 - 50 % dry matter). In order to use efficiently this protein source for using in food industry, it was hydrolysed by different methods into mixtures of peptides and amino acids. So that it has a wide range of applications in food. It can be used as emulsifying agents in a number of applications such as salad dressings, spreads, ice cream, coffee whitener, cracker, and meat products like sausages. However, bitterness in hydrolysates is one of the major undesirable aspects for various applications in food processing. In this study, influences of factors (E/S ratio, pH and temperature) on bitterness of hydrolysate were studied to choose the best hydrolysis conditions by using flavourzyme, alcalase and neutrase. The bitterness of hydrolysate was determined by intensity sensory method (using quinine standard) and amino acid content was analysed by HPLC method. The result showed that bitterness of brewer’s yeast hydrolysate by flavourzyme is the lowest and that by neutrase is the highest. In particular, the bitterness of hydrolysates have reached values of  15.2–40.42 µmol quinine/l (FH - flavourzyme hydrolysate), 21–64.99 µmol quinine/l (AH - alcalase hydrolysate) and 34.62–64.26 µmol quinine/l (NH - neutrase hydrolysate), respectively. The hydrolysis conditions in using flavourzyme were chosen at 50 oC, pH 7, E/S ratio 7.1U/g and in using alcalase - at 55 oC, pH 8, ratio E/S 7.2 U/g, respectively. At this conditions, bitterness reached values 15.44 µmol quinine/l (in FH) and 21.16 µmol quinine/l (in AH).
OPTIMIZATION FOR BATCH PROTEOLYTIC HYDROLYSIS OF SPENT BREWER’S YEAST BY USING PROTEASES
Authors: Thanh Ngoc Nguyen Thi
Published: April 2018

The yield of proteolylic hydrolysis for spent brewer’s yeast by protease and aminoacid contents of hydrolysates (the main  factors influencing in taste of hydrolysed product) depends on factors influencing in catalytic activities of enzymes as temperature, pH value, type of used  enzymes and ratio enzyme/substrate. With the purpose to hydrolyse the spent brewer’s yeast for food application, bitterness of hydrolysate takes the firth consideration, and than the yield of hydrolysing process plays economic role. In this paper, it is dealt with determination of optimal conditions to obtain the highest yield of hydrolysis process and the lowest bitterness of hydrolysate (the bitterness is determined by sensory evaluation, expressed equivalently with concentration of quinine). Response surface methodology (RSM) was used to determine optimum condition for batch proteolytic hydrolysis of spent brewer’s yeast. The influencing factors were investigated as temperature (X1): 40 oC–60 oC; pH (X2): 6.0–9.0, ratio E (flavourzyme)/S (X3): 5–10 U/g and hydrolysis time (X4): 6–9 hours. The experimental responses including degree of hydrolysis (Y1) (%) and bitterness of hydrolysate (Y2) (μmol quinine/ml) are performed in second-degree model. The optimal conditions for obtaining high degree of hydrolysis and low bitterness are determined: Ratio of enzyme mixture (alcalase 7.5 U/g and flavourzyme 8.5 U/g), pH 7.5, hydrolysis temperature at 52oC and hydrolysis time 9 hours. Under the optimal conditions, the actual values obtained for the yield of hydrolysis was 40.81  ± 0.044 % and the bitterness equivalently with concentration of quinine was 16.37 ± 0.03 μmol quinine/ml.
EFFECTS OF FEED ON THE SURVIVAL RATE, GROWTH RATE AND METAMORPHOSIS TIME OF THE WHITE LEG SHRIMP LARVAE (Litopenaeus vannamei Boone, 1931) AT ZOEA STAGE
Authors: Cong Nguyen Van
Published: April 2018

The larvae of white leg shrimp (Litopenaeus vannamei Boone, 1931) at phase nauplii 6 fed with a stocking density of 150 pcs per litre and 3 formula including formula 1 with dry microalgae Spirulina + artemia as main ingredients, formula 2 with microalgae Thalasiosira weissflogii + artemia as main ingredients and formula 3 with microalgae Thalasiosira pseudonana + artemia as main ingredients. Experiments were carried out in 18 tanks fifty-litre composite at Quang Binh branch of C.P Vietnam Corporation. The study results show that, with formula 3, white leg shrimps larvae at zoea stage have the highest growth and survival rates (86.57 %), followed by formula 2 (76.03 %) and finally formula 1 (67.90 %). White leg shrimps larvae at zoea stage in formula 3 have the shortest metamorphosis time (78.61 hours), followed by formula 2 (83.25 hours) and the longest in formula 1 (94.10 hours).
STUDY ON THE GROWTH OF BACILLUS VELEZENSIS M2 AND APPLYING IT FOR TREATMENT OF THE CATTLE SLAUGHTERHOUSE WASTEWATER
Authors: Thu Lan Tran Thi
Published: April 2018

Wastewater from cattle slaughterhouse usually contains high COD and total nitrogen concentration, which required to be treated properly in order to prevent pollution. Strain Bacillus velezensis M2 isolated from Thinh An slaughterhouse, has high ability to degrade organic pollutants rapidly and, therefore, it can be used to produce biological product for slaughterhouse wastewater treatment in large scale, thus reduce setting-up time of operation. In this study, we showed that the best conditions for Bacillus velezensis M2 to grow are NA medium, initial pH of 6.5, inoculum of 3 % (v/v), shaking of 200 rpm. For test in laboratory-scale of 500 ml flask, Bacillus velezensis M2 was induced in the cattle slaughterhouse water containing COD of 1260 mg/L and total nitrogen of 137 mg/L, shaking at 200 rpm, inoculum 3 %, after 12 hours the removal efficiency in COD and total nitrogen were 93.2 % and 83.5 %, respectively.
ANTIBACTERIAL ACTIVITY OF HYDROLYZED VIRGIN COCONUT OIL BY IMMOBILIZED LIPASE
Authors: Ai Van Nguyen Thi
Published: April 2018

The aim of this study was to investigate the hydrolysis conditionsof virgin coconut oil (VCO) by immobilized lipase (Lypozyme TL IM). Then the hydrolyzed products wereevaluated with their antibacterial activityagainst Gram – negative and Gram – positive bacteria (Escherichia coli (ATCC 25922), Salmonella enteritidis (ATCC 13076), Staphylococcus aureus (ATCC 25923) and Bacillus cereus (ATCC 25924)).The effect of four factors on hydrolysis degree of VCO was investigated: the ratio of VCO to buffer, the ratio of enzyme to substrate, pH condition, and temperature.The best reaction conditions in the case of using Lypozyme TL IM as the catalyst was determined: the ratio of VCO to buffer of 1.3 (g/g); the ratio of enzyme to substrate of 0.5 (%),  pH of 8.0 and temperature of 65 oC, VCO was hydrolyzed in 28 hours, acid value achieved to 188.05 (mg/g). The products of hydrolyzed VCO (HVCO) showed activity against Salmonella enteritidis (ATCC 13076) at the concentrations of 5 % and against Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923) and Bacillus cereus (ATCC 25924) at the concentrations of 20 %.
ANTIMICROBIAL ACTIVITIES AND INTERACTION EFFECTS OF VIETNAMESE LITSEA CUBEBA (LOUR.) PERS ESSENTIAL OIL AND ITS ENDOPHYTIC ACTINOBACTERIA
Authors: Van Nguyen Hai
Published: April 2018

The aim of this study was to evaluate the antimicrobial activity of Litsea cubeba (Lour.) Pers (L. cubeba) essential oil and its endophytic actinobacterial crude extracts (EACE) against pathogenic bacteria in individual and in combination. Using the broth micro-dilution assay, the results indicated that both L. cubeba essential oil and its EACE showed inhibition effect against Aeromonas hydrophila ATCC 35654, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 13061, and drug resistant strains such as: Methicillin-resistant Staphylococcus epidermidis (MRSE) ATCC 35984 and Methicillin-resistant Staphylococcus aureus (MRSA) ATCC 33591. The minimal inhibitory concentration (MIC) of L. cubeba essential oil and its AECE were from 3.13 to 6.25 µl ml-1 and 50.0 to 333.3 µl ml-1 respectively. From the indices of fractional inhibitory concentration (FIC) of the combination of L. cubeba essential oil and its EACE, the synergistic effects were found against E. coli, S. aureus, B. cereus and MRSE. The combination treatment of L. cubeba essential oil and its EACE enhance the inhibition effect against food-borne bacteria 16 times comparing with individual treatment.
IMPACTS OF LIQUEFACTION TIME AND ENZYMES ON ETHANOL YIELD OF VERY HIGH GRAVITY PROCESSFOR BEVERAGE ETHANOL PRODUCTION
Authors: Son Chu Ky
Published: April 2018

Most beverageethanol plants in Vietnam have been using the conventional process for ethanol production including liquefaction (95 – 105 oC) of a mash containing less than 200 g/l dry matter, saccharification (60 – 62 oC), fermentation (30 – 32 oC) and distillation. In this work, we developed a simultaneous saccharification and fermentation (SSF) process of rice mash at very high gravity (VHG) and investigated the impacts of liquefaction time and different enzymes on the ethanol yield of SSF-VHG process. Broken ricewas dissolved in tap water to reach 308 g/l dry matter, then the mixture was liquefied at 85 oC for either 60 minor 120 min by using alpha-amylases(Liquozyme and Spezyme Alpha), beta-glucanases(Optimash TBG and Viscozyme). SSF of liquefied mash was performed at 30 oC with the simultaneous addition of glucoamylases(Distillase ASP, Spirizyme and Amigase Mega L)with and without of protease (Fermgen),active dry yeast (Ethanol Red at 1.5 × 107 cells/ml), urea (12 mM) and KH2PO4(4 mM). Under these conditions, SSF-VHG processes finished after 96 h and achieved 15.4 - 16.5 % v/v ethanol, which were equivalent to corresponding to ethanol yield of 83.5 - 89.5 % of the theoretical yield.The increasing liquefaction time and the usage of Liquozyme, Viscozyme showed positive effects on the ethanol yield of the SSF-VHG process. Therefore, these preliminary results could be of importance to optimize the SSF-VHG process.
PHÂN LẬP VÀ ĐÁNH GIÁ ĐẶC TÍNH CHỦNG ASPERGILLUS BRUNNEOVIOLACEUS FEC 156 SINH TỔNG HỢP HỆ ENZYME THỦY PHÂN XYLAN
Authors: Thành Đặng Tất
Published: April 2018

Việt Nam nằm trong vùng khí hậu nhiệt đới với hệ vi sinh vật phong phú và hứa hẹn mang lại những ứng dụng vô cùng đa dạng. Nghiên cứu này tập trung tìm kiếm các chủng nấm mốc mới có khả năng sinh hệ enzyme thủy phân xylan một cách hiệu quả nhằm khai thác ứng dụng trong sản xuất thức ăn chăn nuôi và cồn nhiên liệu. Thông qua việc sàng lọc 164 chủng nấm mốc phân lập từ 82 mẫu đất từ các tỉnh, thành phố khác nhau ở Việt Nam, đã lựa chọn được chủng FEC 156 có khả năng sinh tổng hợp hệ enzyme thủy phân xylan đa dạng với hoạt độ cao (endo-β-1,4-xylanase 187,1 IU/ml; α-glucuronidase 48,5 IU/ml; acetyl esterase 353,4 IU/ml) khi sử dụng 2 % cơ chất cám mì trong quá trình lên men ở 30 ºC, lắc 150 vòng/phút. FEC 156 được định danh là Aspergillus brunneoviolaceus dựa trên đặc điểm hình thái kết hợp với giải trình tự ITS. Động học lên men trên các cơ chất khác nhau cho thấy A. brunneoviolaceus FEC 156 có khả năng tổng hợp xylanase tốt nhất trên cơ chất cám mì (46,1 IU/ml), sau đó là gỗ bạch dương (28,2 IU/ml), và cuối cùng là avicel (4,4 IU/ml). Hoạt tính enzyme xylanase đạt cực đại sau 8 ngày lên men đối với cơ chất cám mì, 9 ngày với cơ chất gỗ bạch dương và 3 ngày với cơ chất avicel. Kết quả nghiên cứu ban đầu cho thấy A. brunneoviolaceus FEC 156 là chủng có tiềm năng và cần được nghiên cứu sâu hơn.
CHEMICAL CONSTITUENTS OF THE RHIZOMES OF Zingiber collinsii Mood &Theilade (ZINGIBERACEAE) GROWING IN VIETNAM
Authors: My Chau Le Thi
Published: April 2018

A chemical investigation of the rhizomes of Zingiber collinsii Mood & Theilade (Zingiberaceae) resulted in the isolation and identification of seven compounds, including a sesquiterpenoid (zerumbone(1)), acoumarin (scopoletin (2)), two flavonoids (quercetin (3), rutin (4)),afurfural derivative (5-(hydroxymethyl)furfural (5)), and two curcuminoids (bisdemethoxycurcumin (6),demethoxycurcumin (7)). The chemical structures of the seven compounds were determined on the basis of NMR and MS analyses.