Tạp chí của Trường Đại học Công nghiệp Thực phẩm Tp. Hồ Chí Minh (nay là Trường Đại học Công Thương Tp. Hồ Chí Minh)
ẢNH HƯỞNG CỦA SÓNG SIÊU ÂM VÀ VI SÓNG ĐẾN TRÍCH LY SAPONIN, POLYPHENOL TỪ QUẢ CHUỐI HỘT Musa balbisiana VÀ ĐÁNH GIÁ HOẠT TÍNH KHÁNG ENZYME XANTHINE OXIDASE CỦA DỊCH CHIẾT THU ĐƯỢC
Polyphenol và saponin là các hợp chất hoạt tính sinh học quan trọng có nguồn gốc từ thực vật với nhiều lợi ích sức khỏe khác nhau, đã thu hút sự chú ý của các nhà nghiên cứu nhằm khai thác chúng từ nhiều nguồn khác nhau. Trong nghiên cứu này, ảnh hưởng sóng siêu âm và vi sóng đến quá trình trích ly polyphenol và saponin từ quả chuối hột được nghiên cứu. Tiến hành tối ưu điều kiện trích ly bằng phương pháp bề mặt đáp ứng (RSM) và đánh giá hoạt tính kháng enzyme xanthine oxidase của dịch chiết thu nhận được. Kết quả cho thấy phương pháp trích ly có hỗ trợ siêu âm cho hiệu suất trích ly polyphenol và saponin từ trái chuối hột cao hơn so với phương pháp trích ly có hỗ trợ vi sóng. Các điều kiện trích ly tối ưu có hỗ trợ siêu âm qua phương pháp bề mặt đáp ứng (RSM) được xác định là công suất 233,85 W trong 15,78 phút thu được hàm lượng polyphenol và saponin lần lượt là 59,07 mgGAE/mgdm và 48,98 mg/mgdm. Hoạt tính ức chế enzyme xanthine oxidase cao với giá trị IC50 = 281,94 μg/mL, chứng tỏ tiềm năng chống bệnh gút cao của dịch chiết thu được.
SO SÁNH HIỆU QUẢ CHIẾT XUẤT LIPID TỪ RONG Sargassum oligocystum BẰNG PHƯƠNG PHÁP ENZYME VÀ SIÊU ÂM
Nghiên cứu này nhằm khảo sát ảnh hưởng của enzyme và siêu âm đối với việc chiết xuất lipid từ rong Sargassum oligocystum. Các điều kiện chiết xuất enzyme hỗ trợ lipid với enzyme bao gồm: tỷ lệ enzyme (0; 0,5; 1; 1,5 và 2 v/w), pH (3,5; 4; 4,5; 5 và 5,5), nhiệt độ (35; 40; 45; 50 và 55 °C) và thời gian chiết xuất (60, 90, 120, 150, 180 phút). Các thông số nghiên cứu là tỷ lệ dung môi (1/5; 1/10; 1/15; 1/20; 1/25 w/v), thời gian (5, 10, 15, 20, 25 phút). Kết quả cho thấy điều kiện thích hợp để chiết xuất lipid bằng Viscozyme L là nồng độ enzyme 1,5%, pH 4,5, ở 50 °C trong 150 phút. Kết quả cho thấy, hiệu quả thu nhận thu lipid từ rong S. oligocystm bằng phương pháp lắc kết hợp xử lý Viscoenzyme L (48,17 ± 0,91%) cao hơn so với phương pháp sử dụng sóng siêu âm (46,88 ± 1,03%).
NGHIÊN CỨU ỔN ĐỊNH BETACYANIN TỪ CỦ DỀN BẰNG PHƯƠNG PHÁP BAO GÓI TRONG HẠT GEL ALGINATE-CHITOSAN
Betacyanin là hợp chất hữu cơ đóng vai trò tạo màu đỏ trong củ dền; đây cũng là nhóm chất màu tự nhiên có thể dùng làm chất tạo màu thực phẩm. Để việc khai thác và tận dụng chất màu thực phẩm tự nhiên từ nguồn nguyên liệu ổn định tại địa phương được khả thi và bắt kịp xu hướng trong những năm gần đây, các nghiên cứu giúp tăng độ ổn định của chất màu tự nhiên là công việc cần được thực hiện. Trong nghiên cứu này, dịch chiết giàu betacyanin được thu nhận bằng phương pháp ngâm chiết không gia nhiệt với hàm lượng betacyanin thu được là 24,93 ± 0,20 mg/L; sau đó, betacyanin được bao gói trong hạt gel alginate-chitosan hiệu suất bao gói đạt được là 90,85 ± 0,96%. Phương pháp bao gói betacyanin trong hạt gel alginate phủ chitosan phân tử lượng trung bình cho thấy khả năng tăng độ ổn định của betacyanin sau khi trích ly. Nồng độ chitosan phù hợp để phản ứng với alginate được xác định là 1,5% và mô hình động học bậc nhất được sử dụng để mô tả quá trình thoái hóa nhiệt của betacyanin với hằng số tốc độ thoái hóa và chu kỳ bán rã được xác định thông qua phương trình động học
ẢNH HƯỞNG CỦA SÓNG SIÊU ÂM ĐẾN QUÁ TRÌNH THU NHẬN TRITERPENOIDS VÀ HOẠT TÍNH CHỐNG OXY HÓA CỦA RỄ SÂM CAU C. orchioides
Mục tiêu của nghiên cứu này là nghiên cứu ảnh hưởng của sự hỗ trợ sóng siêu âm đến quá trích ly để thu hồi triterpenoids và hoạt tính kháng oxy hóa của rễ sâm cau C. orchioides sử dụng phương pháp bề mặt đáp ứng (RSM). Những thông số của quá trình trích ly có sự hỗ trợ của siêu âm (UAE) trong nghiên cứu đã được khảo sát gồm nhiệt độ trích ly (30 - 60°C), công suất siêu âm (150 - 350 W), và thời gian siêu âm (5 - 45 phút). Mô hình bề mặt bậc hai đã được thiết lập và xử lý thống kê được sử dụng để đánh giá mô hình. Kết quả cho thấy hiệu suất thu nhận triterpenoids và hoạt tính kháng oxy hóa (khả năng bắt gốc tự do ABTS) bị ảnh hưởng đáng kể bởi nhiệt độ và thời gian (p<0.05). Điều kiện tối ưu cho quá trình thu hồi triterpenoids và ABTS là nhiệt độ 50,63oC, công suất 322,5W và thời gian siêu âm 44,9 phút. Tại điều kiện này, kết quả thực nghiệm tương tự với kết quả dự đoán trên mô hình. So với phương pháp trích ly truyền thống thì phương pháp UAE cho giá trị hàm lượng triterpenoid và ABTS cao hơn. Khi phân tích GC-MS, dịch chiết có 6 hợp chất có khả năng kháng oxy hóa. Điều này có thể cho thấy phương pháp UAE là một phương pháp đầy hứa hẹn, hiệu quả và kỹ thuật xanh để trích ly các hợp chất có hoạt tính sinh học từ rễ sâm cau C. orchioides.>
DIFFERENCE BETWEEN STATISTICS MIND AND MATHEMATICS THINKING IN TEACHING MATH
More and more countries are implementing an approach to teaching mathematics in high schools in the direction of developing mathematical competence. Vietnam's 2018 Mathematics general education program has clearly demonstrated an innovative point of view in this approach. In which, forming and developing mathematical thinking and statistical thinking abilities is one of the important goals of teaching mathematics. The article wants to clarify the difference between statistical thinking capacity and mathematical thinking capacity, how to distinguish and choose between them to solve problems. The purpose is to support the construction and organization of teaching activities of teachers.
EXPONENTIAL DECAY OF WEAK SOLUTION OF THE DIRICHLET PROBLEM FOR THE NONLINEAR KIRCHHOFF IN AN ANNULAR MEMBRANE
This paper is devoted to the study of the nonlinear Kirchhoff wave equation in an annual associated with homogeneous Dirichlet boundary conditions. At first, by applying the Faedo[1]Galerkin, we prove existence and uniqueness of the solution of the problem considered. Next, by constructing Lyapunov functional, we establish a sufficient condition such that any global weak solution is general decay as t → +¥
ANOMALY DETECTION METHOD FOR NETWORK ATTACK WARNING
In this study, the authors propose an anomaly detection method to warn of network attacks by using the Elastic Stack toolkit to collect and analyze log data of applications; then apply machine learning and PCA algorithm to detect behaviors, signs, anomalies in log data, thereby predicting user actions on applications that are attacks, invasions unauthorized entry or normal access; also compare the warning results of the proposed method with the Elastic machine learning technique being used in the Elastic Stack toolkit.
A PROPOSAL OF CUT ORDER PLANNING SOLUTION BASED ON MS EXCEL SOFTWARE FOR TEACHING PURPOSES
This study creates an application based on Excel software which proposes appropriate cut order planning from industry garment orders. The implementation process includes starting the application, confirming how many garment sizes, how many fabric colors, and then declaring parameters of the order to consider the cut order planning in the fastest time. The application also supports the preparation of documents/reports for the cut order planning, calculates the fabric consumption and creates statistics reports of the cutting table data. The application was tested on two groups of students from the Faculty of Garment Technology and Fashion (Ho Chi Minh City University of Food Industry), with each group consisting of 112 students. The results show that the application can optimize timing, marker making, cut table and manpower and can be a powerful tool applied to courses for students of the Textile and Garment Faculty, in comparison to manual planning. It is also an effective cut order planning data storage solution in the Garment industry
SIMULATION OF CALCULATING AND DESIGNING COIL AND JACKET HEAT EXCHANGER ON MATLAB SOFTWARE
This article focuses on calculation and design procedure for one of the most popular heat exchangers (the “coil and jacket”) and on simulation of this process using Matlab software. Our research shows that the Hot and cold fluid temperatures, also that the type of fluid, flow rate and heat exchanger type are important factors that have great influence on results. Simulating the problem on Matlab software may help shorten time for calculation and design, and give results very quickly when input parameters change.
MODIFIED CORN STARCH: OPTIMIZATION OF MODIFICATION CONDITIONS BY THE RESPONSE SURFACE METHODOLOGY
This article presents the results of using the response surface methodology with a central composite design (RSM-CCD) to optimize the oxidation process of corn starch with a sodium hypochlorite agent. The model is designed as 18 experiments with six experiments at the center to build for three survey factors inclusive of active chlorine concentration, temperature, and pH. Combined with the single-factor survey, two parameters are starch content and corn starch oxidation time. Optimal conditions were found: temperature 51.85°C; active chlorine concentration 3.74% ; pH 9.06; starch content 40% and oxidation time 90 minutes. The highest degree of oxidation was achieved at 0.719% with carbonyl and carboxyl groups of 0.075% and 0.649%, respectively. The FTIR spectrum of oxidized corn starch appeared absorption peak at 1744 cm-1 correspond to the oscillation of the C=O group, indicating that the oxidation reaction has occurred.
EVALUATION OF ENGINEERING PROPERTIES OF HIGH-VOLUME FLY ASH CONCRETE (HVFC) USING LIME AND SILICA FUME ADDITIVES
High-volume fly ash concrete (HVFC) has been studied recently to solve the ash pollution of thermal power waste and environmental problems caused by the cement manufacturing industry. This study was conducted to produce concrete specimens with 70% ordinary portland cement (OPC) to be replaced by fly ash (FA, in wt.). Adding lime and silica fume additives have significantly improved the engineering properties of the HVFC products. The engineering properties such as compressive strength, flexural strength, split strength, and water absorption were evaluated according to Vietnamese standards (TCVN) being applied to commercial concrete on the market. The research results of HVFC samples were also compared with the control products according to the curing age of 3 days, 7 days, and 28 days.
EFFECT OF TEMPERATURE ON CHEMICAL PROPERTIES OF CASSAVA STARCH
Today's tapioca starch is not only a food but also widely used in industries such as food, pharmaceuticals, chemical cosmetics, and light industries such as confectionery, synthetic fibers, edible film preservation, etc. In these applications, cassava starch gelatinized by heating in water is the commonly used processing method. This process leads to the swelling and disintegration of the granules and the dissolution of amylose molecules from the starch granules. Thus, affecting the gelatinization temperature, solubility, swelling capacity, and viscosity of the starch, are important properties that determine the product features produced. DSC thermal analysis diagram shows that tapioca starch has a temperature transition range (Te – To) with initial temperature (To), peak temperature (Tp), and end temperature (Te) during gelatinization. From there, as a basis to survey and evaluate the change of swelling ability, solubility, and viscosity of tapioca starch at the above temperature ranges (Te - To). These properties were also evaluated for their ability to gel, hydrolyze, form films, and interact with starch granules during processing. From there, select the appropriate temperature to control or modify the physicochemical properties of cassava starch for application in food.
MICROPROPAGATION OF Philodendron ‘Imperial Red'
This study performed the micropropagation procedure of Philodendron 'Imperial Red' derived from in vitro shoot. The results showed that MS medium supplemented with 1.5 mg/L benzyl adenine (BA) was suitable for the shoot multiplication stage; the number of newly formed shoots reached 6.50 shoots/explant after six weeks of culture. In the next stage, in vitro shoots were transferred to MS medium supplemented with 0.5 mg/L indole-3-butyric acids (IBA) for rooting. After eight weeks of culture in in vitro conditions, 100% of plantlets were rooted, with the average number of roots reaching 14.55, the length reaching 4.38 cm and the number of leaves reaching 6.83. The plantlets then adapted well when planted in nursery conditions, with a survival rate of 100%, average plant height of 6.80 cm, leaf length of 5.27 cm, leaf width of 2.90 cm and SPAD index of 11.68 after four weeks of planting. The number of stomata and SPAD index of plants at different growing stages were also collected in this study. The number of stomata increases gradually in the order of stages: plants grown in vitro, plants grown in nursery, and plants grown under natural conditions (mature plants). The SPAD index also changed, in increasing order: plants grown in the nursery, plants grown in vitro, and plants grown under natural conditions (mature plants). The obtained results of the study contribute to the development of a micropropagation process for this plant with high propagation coefficient and good quality seedlings, providing seedlings for the floricultural trade in Vietnam.
INVESTIGATION OF SEVERAL PARAMETERS AFFECTING THE PRODUCTION OF FERMENTED SOYBEAN AND LOTUS SEED SAUCE USING Aspergillus oryzae
Soy sauce, the traditional condiment in many Asian countries, is produced from the fermentation of soybeans using Aspergillus oryzae. In this study, lotus seeds were used to partially replace soybeans in order to diversify the flavor of the traditional product. The two main stages in the soy sauce production process studied were the koji production stage from the fermentation using A. oryzae and the moromi production stage from the mixture of koji and a 10% brine. The results showed that the suitable lotus seed : soybean ratio for soy sauce production was 7:3 (w/w). The temperature and duration time of fermentation for koji-making were 30oC for 72 hours with a protease activity of 1279.46 ± 13.22 (U/g). The koji was then mixed with 35% (v/w) of a 10% brine and fermented at 50oC for 72 hours. The formol nitrogen content in the moromi was determined to be around 6.01 ± 0.10 (g/L). The research results show that lotus seed is the potential additional material for soysauce production while providing some basic information on lotus seed soy sauce production to support further studies in order to improve product quality
ASSESSING THE SITUATION AND SETTING UP THE ONLINE SUBJECT EXAMINATION PROCESS AT THE HO CHI MINH CITY UNIVERSITY OF FOOD INDUSTRY
The COVID-19 pandemic has changed many activities, including teaching, and learning activities. This study aims to set up the protocols for an online, open book, essay-based exam at Ho Chi Minh City University of Food Industry. By the online survey using Google Form, the result showed that more than 90% of learners have either a smartphone and/or a laptop, meeting the basic conditions for the online exam process in general as well as the online essay[1]based exam in particular. The online essay-based exam protocols has been piloted with 23 courses, 352 virtual examination rooms, 7278 entries. The average test submission success rate is 97.28% in the condition that learners have limited access to high-speed connections. Besides, learners also evaluate the implementation process clearly and conveniently. The online essay exam process is generally applicable to the entire University of Food Industry in Ho Chi Minh City as well as to units in need.
MINING TOP-K CORRELATED HIGH UTILITY ITEMSETS ON TRANSACTION DATABASE
In this paper, we propose a new research direction, which is to exploit the top-k Correlated High Utility Itemset (TCHUI) on the transaction database. Combination of mining Correlated High Utility Itemsets and mining Top-K High Utility Itemsets to find the top-k correlated high utility itemsets on the transaction database. To address this issue, we combine the Correlated High Utility Itemset (CoHUI) mining with the threshold raising strategies and propose the TCH algorithm. This algorithm uses the Utility List data structure to store data about the utility of itemsets, uses the Kulc threshold to measure correlation, and applies several pruning strategies such as U-Prune, TWU -Prune, LA-Prune to reduce the search space. Besides that, the threshold raising strategies are applied such as RIU, LIU-E, and RUC to exploit the TCHUI set effectively. Our experiment results on large datasets including Chess, Mushroom, Retail, and Chainstore and compare with the state-of-the-art THUI algorithm. The results show that the proposed algorithm has better performance than the THUI algorithm in terms of execution time and memory usage.
SECURITY IN ENERGY HARVESTING OVERLAY-BASED COGNITIVE RADIO NETWORKS
This paper proposes a security solution for an energy harvesting overlay-based cognitive radio network. The solution applies artificial noise to jam the received signal at the eavesdropper. The security performance of this network is evaluated through the secrecy outage probability. Multiple results are provided to derive insights into the security of this network when artificial noise is applied, thereby determining optimum system parameters for maximum network security. Remarkably, primary/secondary communications can be secured at different levels by dynamically adjusting many system parameters of the proposed solution.
OPTIMIZATION OF DRYING CONDITIONS OF INFRARED RADIATION-ASSISTED THERMAL PUMP ON RAW FISH (Pseudapocryptes elongatus)
Goby fish bought in Ca Mau city was dried by infrared radiation-assisted heat pump technology, based on Box-Wilson's multi-factor optimal experimental design with impact factors (drying temperature (X1), the concentration of sorbitol (X2), wind speed (X3), and the objective function is the hydration ratio (Y, %). The optimal sample was controlled with the dried sample by heat pump technology and sun drying technology, based on the sensory characteristics, impurities, water activity, total nitrogen, total protein, total aerobic microorganisms, E. coli, Coliforms, Samonella, V. cholerae, and S. aureus. The results showed that rehydrate ratio, drying temperature, wind speed, and sorbitol concentration correlated with each other according to the equation Y = 59,9143 + 0,751607*X1 + 1,71339*X2 + 1,24464*X3- 0,62464* X1X2 - 0,668393* X1X3 + 1,09839* X2X3. Drying temperature affects drying time more than other factors. Optimal conditions for drying goby are sorbitol 10.0%, drying temperature 56 oC, wind speed 2.4 m/s, and a drying time of 5.70 hours with the highest rehydration rate of 62.50%, shortest drying time and higher sensory quality and food safety than air drying and sun drying methods.
EFFECTS OF THE RATE OF ENZYME ALCALASE AND PAPAIN ON THE HYDROLYSIS OF SALMON CARTILAGE (Salmon salar)
This paper presents the results of the study on the effect of the ratio between enzyme alcalase and papain on the content of soluble protein, peptide, Naa, NNH3, and chondroitin sulfate formed in hydrolysing salmon cartilage (Salmon salar) by alcalase-papain mixture. The results showed that the suitable ratio of alcalase/papain in the mixture of alcalase-papain enzyme for salmon cartilage hydrolysis is 60/40. After 4 hours of salmon cartilage hydrolysis by alcalase-papain mixture at enzyme concentration of 0.4%, temperature of 55 °C, natural pH (6.8), sample weight of 2 kg and the addition of 2-liter water ratio, the hydrolyzate has the content of protein, peptide, Naa, chondroitin sulfate and NNH3 higher than 1.43 times, 2.81 times, 2.31 times, 12.19 times and 1.22 times higher than the original
EVALUATING CONSUMER BEHAVIOUR FOR GINSENG SUPPLEMENT PRODUCTS BY MULTIFACTORIAL CORRELATION ANALYSIS AND CLUSTERING
The health support food market is growing rapidly, but the consumer’s requirements for this product are also very strict and diverse. This study was conducted to build the image of potential customers based on their survey preferences and habits. Survey data were randomly collected from 306 individuals in Tan Phu District, Ho Chi Minh City and were represented by consumers in the region. The data set was processed by multifactorial correlation analysis and showed the relationship between them by clustering. The obtained results showed that the potential customers have characteristics such as women, office workers, aged 30 years and older with incomes from 10 to 20 million VND per month, buy goods at stores ginseng specializing store, liked the glass bottle, bought product for self use and only used tea with ginseng added. The results of this research can be used to develop new product or further research on the consumer market of ginseng supplements.
STUDY OF SAMPLE PREPARATION OF SEED OILS WITH CONJUGATED FATTY ACIDS FOLLOWED BY HPLC
Conjugated fatty acids have been shown to possess many valuable biological activities, including anticarcinogenic, antiatherogenic, anti-inflammatory, and antidiabetic effects and immune-modulating properties. However, these compounds are susceptible to external factors (temperature, light) and easily decomposed and oxidized during separation, extraction, and sample processing prior to analysis. In this work, a fast and efficient sample preparation procedure for analyzing triacylglycerol compositions containing conjugated fatty acids in seed oils was studied. The sample preparation procedure consists of three stages: the rapid determination of the presence of conjugated double fatty acids in seed oil using UV spectroscopy; solvent extraction of seed oil at room temperature; oil purification using solid phase extraction with silicagel as stationary phase. The results showed that the molecular absorption spectra of seed oil in n-hexanee in the wavelength range of 220-400 nm could be used to quickly detect the presence of fatty acid moieties, containing conjugated double bonds in oil. The seed oil was extracted at room temperature using three different solvents in polarity: n-hexane, dichloromethane, and acetone; and compared with the traditional Soxhlet extraction method. The seed oil was purified by solid phase extraction using silicagel as the stationary phase. The catalytic activity of silica gel with analytical compounds absorbed on the stationary phase of solid phase extraction columns was controlled and discussed.
SYNTHESIS OF EPOXIDATION SOYBEAN OIL RESIN AND ANALYZE MECHANICAL PROPERTIES OF EPOXY ESTER COATING FILM
Epoxy resin DER 671X75 was modified with fatty acids of soybean oil to improve the toughness of epoxy resin. Fatty acids of soybean oil were separated by saponification with sodium hydroxide solution and acidification with acid sulfuric. Extracted fatty acids and the epoxidized soybean oil resin were characterized by Fourier Transform Infrared Spectrometry (FTIR). The results showed the effects of saponification and acidification conditions on the properties of fatty acids. Epoxy ester resin is synthesized from epoxy resin DER 671X75 and fatty acids of soybean oil with a ratio mass of epoxy resin and fatty acids is 1:2 (wt/wt), reaction temperature of 220 oC, and reaction time with 6 hours for the highest reaction level. Epoxy ester resin was able to form coatings film, and mechanical properties of epoxy polymer coatings film were increased
PHOTOCATALYTIC DEGRADATION OF METHYLENE BLUE USING ZINC OXIDE NANOPARTICLES
Zinc oxide nanoparticles were synthesized by a simple sol-gel method with Zinc acetate dihydrate as the precursor. The photocatalyst structure was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The catalyst was synthesized at 400-700 °C calcination conditions, the results show that the zinc oxide nanocrystal size is 22 - 32 nm, highly effective in photocatalysis, the decomposition of methylene blue. Their photocatalytic activities for methylene blue degradation were evaluated in a batch reactor under simulated visible light using a special 26 W compact lamp. The highest photocatalytic activity for methylene blue degradation was observed at 400 °C, resulting in 95.1% photocatalytic degradation yield after 4 h under visible light irradiations
SYNTHESIS OF g-C3N4/CuWO4 COMPOSITE WITH HIGH PHOTOCATALYTIC ACTIVITY UNDER VISIBLE LIGHT
Two-component graphitic carbon nitride and copper tungstate (g-C3N4/CuWO4) composite photocatalyst was successfully synthesized by a sonication-assisted calcination method at various temperatures of 530 oC. The as-prepared samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis-DRS), and Scanning electron microscope (SEM). The absorption of g-C3N4/CuWO4 is enhanced distinctly in the visible light region compared to that of pure g-C3N4 and CuWO4. The tetracycline (TC) degradation evaluated the photocatalytic performance of material. Results show that, the photocatalytic degradation efficiency of TC by g-C3N4/CuWO4 under visible light irradiation reaches 80.57% after 3 hours. The enhanced photocatalytic activity of g-C3N4/CuWO4 composite was predominantly attributed to the synergistic effect, which increased visible-light absorption and facilitated the efficient separation of photoinduced electrons and holes (Z-scheme).
EFFECT OF SPRAY DRYING ON CONCENTRATED JUICE BITTER GOURD
The present study used the spray drying method to produce soluble bitter melon powder from the bitter melon grown in Vietnam. The influence of technological parameters on the spray drying process of soluble bitter melon powder was investigated. The processing conditions were found as follows: bitter melon after concentration at a dry matter content of 10%, addition rate of maltodextrin at 20% w/v (based on the volume of the concentrate dried at 150 °C), inlet flow rate at 300 mL/h, nozzle pressure at 2.5 bar. The received product had a moisture content of 4.38%, ash of 5.07%, water solubility index (WSI) of 87.91% and still retained the characteristic taste and smell of the bitter melon
PRINCIPAL COMPONENT ANALYSIS AND CLUSTER ANALYSIS TO EVALUATE THE SEASONAL VARIATION IN THE CHEMICAL COMPOSITION OF TEA TREE OIL
The tea tree, scientifically known as Melaleuca alterfolia (Maiden & Betche) Cheel, is native to Australia and has strong antibacterial, antifungal, and antiviral properties. The purpose of this study was to evaluate the influence of seasonal variation on the yield and chemical composition of tea tree oil over a 12-month period. Tea tree oil was extracted by the hydrodistillation method in the support of a surfactant solution (650 ppm). During the survey period, the essential oil content ranged from 4.24% to 6.61%. The constituents of TTO were determined using GC-FID and GC-MS, as well as multivariate analysis: principal component analysis (PCA) and cluster analysis. Nine main components in TTO were a-pinene (2.0-2.5%), 1,8-cineole (3.2-5.5%), a-terpinene (8.3-12.1%), p-cymene (1.8-4.3%), limonene (1.0-1.4%), g-terpinene (16.1-21.4%), terpinolene (2.1–3.5%), terpinen-4-ol (40.6–49.6%), and a- terpineol (3.1–6.6%). The results of the analysis showed that the essential oil content was highest during the summer months when there was a lot of rain, while the composition of the main compounds in the essential oil changed almost insignificantly depending on the season. Furthermore, the antibacterial activity of pure tea tree oil and a few main components was evaluated
EFFECT OF ENCAPSULATION TECHNIQUE AND Stevia rebaudiana ON Lactobacillus plantarum VIABILITY UNDER SIMULATED DIGESTIVE FLUID
In this study, the effect of different encapsulation methods extrusion (EM) and internal emulsion (IM) methods (with and without the addition of stevia) on Lactobacillus plantarum LV 11 viability during the encapsulation process, as well as under simulated gastric (SGF) and intestinal juices (SIF) were evaluated. The results showed that the encapsulation efficiency of EM samples was significantly higher than IM samples, in which alginate concentration at 2% (w/v) showed the best results in both methods. In the SGF test, the free cell samples showed sensitivity to low pH conditions and no viable cells were recorded after 2 h of incubation. The sensitivity of L. plantarum to SGF medium was significantly higher than that of SIF medium, in which the encapsulation technique showed a significantly improved protective effect of L. plantarum compared to free cells. The addition of stevia to the encapsulation process was necessary to improve the viability of L. plantarum bacteria under simulated digestive fluid. The extrusion technique improved the survival of L. plantarum under SGF conditions compared to the emulsion technique. The emulsification technique, with the ability to produce small-sized preparation, but still ensures effective protection of probiotic bacteria that shows the potential for application in food products.
ISOLATION AND DETERMINATION OF SOME HARMFUL MOLDS ON POST-HARVESTED DRAGON FRUIT PEELS Hylocereus costaricensis
The dragon fruit is a fruit with high nutritional, economic value for Vietnam but it has a short shelf life. Harmful mold is one of the causes of post-harvest quality loss of dragon fruit. This study was conducted to find out harmful mold strains on the dragon fruit peel Hylocereus costaricensis during post-harvested storage. By inoculating nine damaged peel samples of the dragon fruit H. costaricensis from a dragon fruit garden in Long An province on the selective agar media Czapeck-Dox, five mold strains were isolated and purified. Basing on the macroscopic (colony morphology) and microscopic (cell morphology observed by light microscope) characteristics, strains N1 and N2 could belong to genus Fusarium, strain N3 could belong to genus Neoscytalidium, strain N4 could belong to the genus Rhizopus and strain N5 could belong to the genus Aspergillus. Two mold strains N1 and N3 were further identified as Fusarium fujikuroi (100% similarity) and Neoscytalidium sp. (100% similarity) by sequence analyses of ITS and LSU regions of rRNA gene in combination with morphological characteristics, respectively. The artificial infection examination showed that both F. fujikuroi N1 and Neoscytalidium dimidiatum N3 strains caused the damages on fruits after harvest. The obtained results of this study provided more data of harmful molds, thereby helping to guide the prevention and preservation of post-harvested dragon fruit Hylocereus costaricensis in Viet Nam.
EFFECT OF HYDROLYZATION CONDITIONS ON EXTRACTION CAPACITY OF CATECHIN OF CASHEW NUT TESTA WITH THE SUPPORT OF ENZYME VISCOZYME L AND PECTINEX ULTRA-L PRODUCTS
The objectives of this study are to investigate appropriate hydrolyzation conditions to obtain the highest amount of catechin of the cashew nut testa using the enzyme-assisted extraction method. Two types of enzymes, Viscozyme L and Pectinex ultra-L, were used to study with different conditions including enzyme concentration, sample/buffer ratios, temperature, and incubation time. The results indicated that the highest catechin concentration (16.09 ± 0.73 g CE/100g dried sample) was obtained when Viscozyme L was used to assist the extraction with the concentration of 2%, sample/buffer ratio of 1/30, the temperature of 50oC, and incubation time of 60 min. Regarding the Pectinex ultra-L, the appropriate conditions of enzyme concentration of 2%, sample/buffer ratio of 1/20 (w/v), the temperature of 50oC, and incubation time of 60 min were determined to obtain the highest catechin content of 19.98 ± 0.50 (g CE/100 g dried sample). Moreover, the results also indicated that flavonoid content and DPPH radical scavenging capacity of the extracts from cashew nut testa using Pectinex ultra-L were higher than those of the extracts using Viscozyme L or the control. Thus, the extraction using the Pectinex ultra-L was more effective than that using the Viscozyme L or without enzyme.