Burapha Science Journal

Performance of Recirculation Flow Roof in Wastewater Treatment Systems for Temperature Control Modeling in Floating Melon Greenhouses

Rattapol Suksomboon — 2025-02-18

Background and Objectives : This study on hybrid mathematical modeling aims to enhance the sustainability of agricultural practices in the Chi River basin by developing a wastewater treatment system for high-yield greenhouse cultivation. This system is expected to reduce financial risks associated with flooding and mitigate the worsening degradation of the Chi River. The researcher has designed a rooftop wastewater treatment system using mathematical modeling to regulate the temperature in floating melon greenhouses, addressing both flood-related challenges and wastewater issues. The system utilizes the sloped greenhouse roof (tilted at 20 degrees) to remove biochemical oxygen demand (BOD), ammonia (NH3), and nitrate (NO₃) from wastewater. Furthermore, mathematical models were developed to regulate greenhouse temperature, including the Plug-Flow Volume Temperature Reactor (PFVTR) and the Completely-Mixed Stirred Volume Temperature Reactor (CSVTR). These models, based on first-order and second-order reactions (n = 1 and n = 2), control temperature (T) by adjusting the recirculation ratio (QR/Qin = R) and hydraulic retention time (HRT), utilizing the ratio of cross-sectional area to longitudinal area (A_C: A_L)to determine background concentration temperature (T*) and the Coefficient of Temperature (kT) for model validation.

Methodology : The CTFMG system (Control Temperature in Floating Melon Greenhouses) measures 5.0 meters in width, 3.0 meters in height, and 6.0 meters in length with a floating melon density factor (f) of 0.5 and a total volume of 90 cubic meters. The cross-sectional to longitudinal area ratio (A_C: A_L) is less than 1:4. The system's 18-square-meter plastic-sheet rooftop is inclined at 20 degrees. Water recirculation rates were set at 3, 4, 5, 6, and 7 liters per minute, while wastewater inflow (Qin) was maintained at 1 liter per minute. The treated wastewater was analyzed for BOD, NH3, and NO3 levels. The air exchange system operated with an airflow rate (QAin & QAout) of 576 cubic meters per day, utilizing laminar flow with hydraulic retention times (HRT) of 22.33 and 44.66 days. Temperature measurements were taken during April, the hottest month, to assess the impact on melon production. The input temperature (Tin) was controlled at 36 ± 2.5°C, and the output temperature (Tout) was recorded to determine the effect of different recirculation ratios (QR/Qin = R). Data were processed using Microsoft Excel to calculate background concentration temperature (T*), first- and second-order reaction rates (n = 1 and n = 2), and the Coefficient of Temperature (kT) for both PFVTR and CSVTR models. The accuracy of the mathematical models was verified, and the feasibility of floating melon greenhouses was assessed based on Net Present Value (NPV) and Benefit-Cost Ratio (B/C Ratio), with a one-year project lifecycle.

Main Results : Results from the study on the Control Temperature in Floating Melon Greenhouses (CTFMG) utilize a roof area of approximately 18 square meters, inclined at 20 degrees from the horizontal, for wastewater treatment using plastic sheet materials. The recirculation ratio (Recirculation ratio: QR/Qin = R) tested at values of 3, 4, 5, 6, and 7 achieved removal efficiencies for BOD, NH3, NO3 (Removal BOD NH3 NO3 Efficiency) as follows: (5.36 ± 2.59%, 2.83 ± 2.85%, and 10.00 ± 0.031%), (25.07 ± 2.56%, 20.49 ± 2.83%, and 10.75 ± 0.0295%), (30.14 ± 2.52%, 22.07 ± 2.81%, and 14.25 ± 0.0275%), (59.72 ± 2.49%, 31.29 ± 2.8%, and 23.50 ± 0.027%) and (72 ± 2.45%, 34 ± 2.78%, and 32.50 ± 0.0265%). The efficiency of temperature reduction decreased by 6.81 ± 2%, 8.36 ± 2%, 9.86 ± 2%, 11.32 ± 2%, and 12.74 ± 2%, respectively. The Control Temperature in Floating Melon Greenhouses (CTFMG) system, with a cross-sectional area to longitudinal-section area ratio (A_C: A_L) (< 1:4), achieved the highest treatment efficiency at R = 7, with removal rates of 72 ± 2.45% BOD, 34 ± 2.78% NH3, and 32.50 ± 0.0265% NO3, and a maximum temperature reduction efficiency of 12.74 ± 2%. The system controlled the temperature from an inlet temperature (Temperaturein: Tin) of 36 ± 2.5°C to an outlet temperature (Temperatureout: Tout) of 31.00 ± 1.5°C. From the Plug-Flow Volume Temperature Reactor (PFVTR) and Completely-Mixed Stirred Volume Temperature Reactor (CSVTR) models, first-order and second-order reactions (n = 1 and n = 2) were observed. background concentration temperature (T*) was 15.55 ± 2.0°C. The Coefficient of Temperature (kT) values for both models were as follows: 0.008, 0.00004 (1/day) and 0.0009, 0.00006 (1/day). The coefficient of determination (R²) values were 0.8398, 0.8497, 0.9306, and 0.9526. From the economic feasibility analysis of the floating melon greenhouse for agriculture, based on Net Present Value (NPV), the system yielded 1,680 THB per square meter, with a Benefit – Cost Ratio (B/C Ratio) of 1.68 and a payback period of 1 year.

Conclusions : The Control Temperature in Floating Melon Greenhouses (CTFMG) system exhibited a second-order reaction (n = 2) in the Completely-Mixed Stirred Volume Temperature Reactor (CSVTR) model. The Coefficient of Temperature (kT) was determined to be 0.00006 1/day. In terms of economic feasibility, the floating melon greenhouse demonstrated a Net Present Value (NPV) and a Benefit-Cost Ratio (B/C Ratio) that supported its financial viability, with a payback period of 1 year.

Development and Analysis of Growing Media for Lettuce Cultivating from Used Mushroom Culture

Sutthirak Uansiri — 2025-02-18

Background and Objectives : In Chom Bueng District, Ratchaburi Province, there is a large amount of mushroom farming, especially the oyster mushroom (Pleurotus spp.) farm, which is grown using mushroom cultures. At the end of the mushroom harvest process, there will be used mushroom culture. This waste material is managed by using it as fertilizer in fields and as an ingredient for making new mushroom culture. However, this method may cause infestation from other fungi that are contaminated in the used mushroom culture. Therefore, the biological fermentation process is used to help digest mushrooms or various fungi and is a process to reduce the amount of carbon and nitrogen so as not to affect the plants. So that waste materials from mushroom cultivation have the potential to be applied in the production of plant-growing materials, which will help reduce the amount of old mushroom lumps thrown into the environment. This research, therefore, utilizes the used mushroom culture by making plant material by fermenting it with various types of organic materials. The objective is to reduce the amount of agricultural waste from mushroom farms by developing planting materials for lettuce and to analyze the physical and chemical properties of the planting material.

Methodology : Used mushroom cultures were fermented with organic materials, including cow dung, Rain Tree leaves, raw rice husks, and bamboo leaves, in various proportions, totaling 5 formulas. The results of the fermentation were studied after 40, 50, and 60 days of fermentation. The planting materials were analyzed for physical and chemical properties, including pH, organic matter content, total nitrogen content, phosphorus content, and potassium content. All planting materials were then tested for growing 15-day-old green oak lettuce and red oak lettuce, approximately 1–2 centimeters tall, in 8x16-inch planting bags. Each bag contained 1 kilogram of planting material. For each planting material, 30 plants were used. The plants were watered thoroughly and placed in an experimental greenhouse covered with a black shade cloth filtering 50% of the light. Watering was done at least 1–2 times a day. Growth measurements were performed using a simple random sampling method, selecting 3 plants per type of vegetable. The plant height and number of leaves were measured once a week until the planting period reached 6 weeks. After 6 weeks of growth, bush size, root length, and fresh weight were measured. Before the planting material was analyzed, it was sieved to remove non-degraded materials. This study was designed as a completely randomized trial. Each set of planting material was repeated 3 times. The obtained data were analyzed using a One-Way Analysis of Variance (ANOVA) with the F-test, and the means of the data were compared using Duncan's Multiple Range Test (DMRT). Microsoft Excel was used for data analysis at the p < 0.05 level. Data are presented as mean ± standard deviation (S.D.).

Main Results : The results showed that after 60 days of fermentation, all planting materials were well decomposed. The yield was 60-75% by volume, indicating that the used mushroom culture can be utilized as a mixture of planting material and to reduce the amount of the used mushroom culture into the environment. In addition, all planting material formulations showed significantly different analytical values (p < 0.05). The suitable planting material is Formula 1 (T2), which contained a mixture of used mushroom culture : cow dung : Rain Tree leaves : raw rice husk : bamboo leaves in the ratio of 1 : 1 : 1 : 1 : 1. After fermenting the planting media for 60 days in plastic baskets, the results of physical and chemical analysis were revealed as followed: the pH was 6.0±0.06, the EC was 1.6±0.10 dS/m, the OC content was 7.23±0.01%, OM was 12.47±0.01%, total nitrogen was 1.08±0.06%, total phosphorus was 0.22±0.03% and total potassium was 0.57±0.03%.

Conclusions : This research has used agricultural waste from mushroom farms to develop into planting materials for green oak lettuce and red oak lettuce, which are vegetables with high consumption. The used mushroom cultures were fermented with organic materials in different ratios, totaling 5 formulas. After 60 days of fermentation, the results of the study found that all planting materials decompose well and yield 60-75 percent by volume. The most suitable planting material is the T2 formula, which is a mixture of leftover mushroom spawns: cow dung: crab claw leaves: raw rice husks: bamboo leaves in a ratio of 1: 1: 1: 1: 1. In addition, the study of the physical and chemical properties of this formula of planting materials found that it has a higher amount of nutrients that can support plant growth than other formulas. When the T2 formula of planting materials was used to grow lettuce, it was found that the plants grew better overall than the other formulas. The plants could also be harvested within 40 days without the need for additional fertilizers.

Analysis of Spatial and Temporal Patterns of Meteorological Drought Exposure and Its Impact on Economic Crops, Nakhon Ratchasima Province, Thailand

Suwit Ongsomwang — 2025-02-19

Background and Objectives: Drought is one of the most complex influencing factors among all-natural disasters. It is a complex phenomenon because of the unpredictable start and end of its period, the length of the event, as well as the nonspecific spatial extent or geography and uncertain frequency and intensity. Meanwhile, meteorological drought is usually defined based on the degree of dryness and the duration of the dry period. Nakhon Ratchasima province is a drought-prone area since the annual rainfall between 1975 and 2022 was mostly lower than the average annual rainfall in the same period, with a value of 1,223.59 mm for about 24 years. Therefore, this study aims to examine spatial and temporal patterns of meteorological drought exposure and its impact on economic crops in Nakhon Ratchasima province. The objectives of the study were (1) to classify and map meteorological drought frequency, intensity and exposure and (2) to analyze spatial and temporal patterns of meteorological drought exposure and its impact on economic crops. Herein

Methodology: The research methodology comprised four main steps after the Standardized Precipitation Index calculation in 4 periods, including 3m7 (May to July), 3m10 (August to October), 6m10 (May to October), and 12m (January to December): (1) meteorological drought frequency index extraction and classification, (2) meteorological drought intensity index extraction and classification, (3) meteorological drought exposure index extraction and classification, and (4) spatial and temporal patterns analysis of meteorological drought exposure and its impact on economic crops: rice, cassava, sugarcane and corn. Herein, three meteorological drought indices, meteorological drought frequency, meteorological drought intensity, and meteorological drought exposure, were calculated based on a long-term rainfall record (1975-2022) from 37 stations. In the meantime, spatial and temporal patterns of meteorological drought exposure at district and sub-district levels using zonal analysis with majority operation.

Main Results: The most dominant class of meteorological drought exposure classification of the 4 periods (3m7, 3m10, 6m10 and 12m) was a moderate, moderate, moderate, and low covered area of about 33.22%, 35.26%, 42.11% and 35.69%, respectively. The spatial distribution of the meteorological drought exposure classification of the 4 periods displayed a completely different pattern. Still, the meteorological drought exposure severity classification of the 4 periods showed a strong positive linear relationship among them. The correlation coefficient values varied from 0.8100 to 0.8966. These results imply the similarity of meteorological drought exposure patterns among 4 periods. Besides, the majority severity classification of the meteorological drought exposure in the 6m10 period exhibited the highest impacts at district and sub-district levels, with 16 districts and 138 sub-districts. Based on the spatial pattern changes of meteorological drought exposure severity levels among 3-periods (3m7, 3m10 and 6m10), covering the economic crop calendar, the severity classification of the meteorological drought exposure in the 6m10 period exposed the highest meteorological drought compared with other periods (3m7 and 3m10). In the meantime, the potential impact areas of meteorological drought exposure in the 6m10 period (May to October) at moderate, high, and very high severity levels on rice in 2023 was about 3,939.40 sq. km 64.65% of the total area of rice, cassava about 2,918.67 sq. km 75.74% of the total area of cassava, sugarcane, about 1,423.47 sq. km or 69.48% of the total area of sugarcane, and corn, about 441.33 sq. km or 56.38% of the total area of corn. Furthermore, based on Pearson bivariate correlation analysis, the most dominant meteorological drought exposure index that impacts crop yield is the meteorological drought exposure index in the 3m7 period (May to July). This index displayed a negative linear relationship with the average rice, cassava and corn yield between 2011 and 2022. On the contrary, the meteorological drought exposure index showed no linear relationship with sugarcane since a multi-cropping system of about three years is applied for sugarcane by farmers.

Conclusions: Spatial and temporal patterns analysis of meteorological drought exposure were successfully conducted based on a standardized precipitation index for quantifying the severity of drought and its impact on economic crops in different periods (3m7, 3m10, 6m10 and 12m). The presented research workflow can be used as a guideline for the relevant government agencies, such as the Department of Agricultural Extension and the Department of Disaster Prevention and Mitigation, to monitor meteorological drought for mitigation of the potential impact of drought on economic crops in the future. In addition, early warning systems of meteorological drought at the regional level are recommended to be implemented by the Thai Meteorological Department.

Qualities of Mixed Vegetables/Fruit Juice from Fresh-Cut Salad Waste under High-Pressure Processing

Nattavong Fuangpaiboon — 2025-02-20

Background and Objectives : High pressure processing (HPP) is a non-thermal food processing technology that has emerged as innovative methods capable of microbial inactivation and enzyme inhibition while preserving nutritional value, flavor compounds, and bioactive substances. HHP is a favorable application in food industry including juices, jams, and other fruit products. The core benefits of HHP processing are the reduction or significant elimination of heating, avoiding the degradation of the food component from heat. In addition, there is a large amount of fresh-cut salad waste after the cutting process that cannot be sold due to their unappetizing characteristics but have nutrition values and bioactive substances such as antioxidants, etc., with no difference from fresh salad vegetables. Therefore, food processing is required to change this appearance from food waste to juice but still preserve the nutrient value of the bioactive compounds as much as possible. This study aimed to investigate the effects of high-pressure processing (HPP) at various levels of pressure and time on the physical properties, chemical properties, and microbials of a mixed vegetable and fruit juice product.

Methodology : Three types of vegetables (such as Green oak vegetables, red oak vegetables, and mini cos lettuce) from fresh-cut salad waste) and fruits, including red grapes, red apples, and lemons, were extracted using a cold press processor and then mixed. The proportion of mixed vegetables (Green oak vegetables, red oak vegetables, and mini cos lettuce in the proportion 45:45:10 % by weight, respective), red grapes, red apples, and lemons were 59.58, 23.57, 14.85 and 2 % by weight, respectively. Mixed vegetables and fruit juice were packed in polyethylene terephthalate bottle (PET) for 150 ml. Then, mixed vegetables/fruit juice were examined as pressure levels of 300, 400, and 500 MPa applied for durations of 3, 6, and 9 minutes. All Mixed vegetables and fruit juice samples were physical, chemical and microbiology analyzed such as color, turbidity, total soluble solids content, pH value, total phenolic contents, antioxidant activity by DPPH and FRAP assays, total microbial and yeast and mold contents.

Main Results : Results demonstrated that pressure and time had significant interactive effects on redness (a*) and total microbial count (p≤0.05). Furthermore, pressure levels significantly influenced brightness (L*), redness (a*), yellowness (b*), pH, and antioxidant activity as measured by the Ferric Reducing Antioxidant Power (FRAP) assay (p≤0.05). Mixed vegetables and fruit juice under pressure at 500 MPa for 5 min was increased in a* value (a* = -0.50, p≤0.05). However, pressure levels and time did not affect turbidity and total soluble solids content (TSS) of mixed vegetables and fruit juice samples (p>0.05). Notably, increasing pressure levels correlated with decreased FRAP antioxidant activity (p≤0.05). FRAP contents of mixed vegetables and fruit juice under pressure at 500 MPa with duration between 3 and 9 min ranged from 7.45 to 7.93 µg TE/100 g sample. Pressure levels, times and interaction between pressure levels and time (P*T) did not affect total phenolic contents and antioxidant activity by DPPH assays of mixed vegetables and fruit juice (p>0.05). Total phenolic contents and antioxidant activity by DPPH assays of mixed vegetables and fruit juice ranged from 35.94-41.21 µg GAE/100 g samples and 4.26-4.56 µg TE/100 g samples, respectively. Processing time significantly affected only brightness and pH (p≤0.05). The pH values of mixed vegetables and fruit juice samples under HPP process at 300 MPa for 3-6 min were ranged between 3.83 and 3.84. When pressure level and time increased, total plate count decreased (p≤0.05). Total microbial contents of mixed vegetables and fruit juices under pressure level more than 300 MPa for 3-9 min had ranged from 3.33 to 6.00 CFU/ml. While pressure, time, and their interaction did not significantly impact yeast and mold counts in the juice samples (p>0.05). The results exhibited that total yeast and molds of mixed vegetables and fruit juices under HPP were lower than mixed vegetables and fruit juices with untreated HPP. All treated samples exhibited microbial, yeast, and mold counts below the general criteria and limits set for high-pressure pasteurized acidic products (pH ≤ 4.64). These findings align with the Thai Food and Drug Administration’s (2019) guidelines, which recommend pressures of at least 400 MPa for 1-20 minutes for such products.

Conclusions : High-pressure processing of mixed vegetable and fruit juice at 400 MPa for 6 minutes emerges as a promising non-thermal treatment with potential for industrial application. This HPP condition exhibits a higher of total phenolic contents, and antioxidant activity by DPPH and FRAP assays in mixed vegetables and fruit juices from fresh-cut salad waste. Moreover, microbial, yeast, and mold counts align with the Food and Drug Administration’s (2019) guidelines with an appropriate cost. This method not only ensures microbiological safety and quality but also presents an opportunity to add value to by-products from the fresh-cut produce industry or substandard vegetables, transforming them into nutritious health beverages.

Application of Google Earth Engine for Monitoring Mangrove Forest Changes in Satun Province

Jirawat Jantongpoon — 2025-02-20

Background and Objectives : Satun Province has rich and ecologically important mangrove forests that play a vital role in both the ecosystem and the economy. However, a continuous decline in these mangrove forests has been observed over recent years. Challenges within the study area include limited human resources, which impede effective monitoring and management. Furthermore, conventional remote sensing techniques necessitate specialized hardware, software, and data processing capabilities, thereby imposing limitations on accessibility and efficiency for certain organizations. This study aims to propose a methodology for utilizing Google Earth Engine (GEE), a powerful cloud-based platform for online satellite imagery analysis, to monitor changes in mangrove forest areas in Satun Province, covering the districts of Thung Wa, La Ngu, Tha Phae, and Mueang Satun. This study, covering the six-year period from 2018 to 2023, pursues several key objectives: to mitigate conflicts arising from human encroachment on mangrove ecosystems, to minimize hardware and software costs associated with traditional monitoring methods, and to address the critical issue of mangrove forest decline attributed to persistent encroachment and land use change.

Methodology : This study employed Sentinel-2 Multi Spectral Instrument (MSI) Level-1C and Level-2A imagery acquired during periods of minimal cloud cover over the study area within the specified year. Cloud masking procedures were implemented to mitigate cloud contamination, and vegetation indices, including the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index (SAVI), and Enhanced Vegetation Index (EVI), were computed to generate training data for supervised land cover classification. Supervised classification was performed using the Random Forest algorithm, a robust machine learning classifier, with 30 iterations, implemented within the Earth Engine Code Editor on the Google Earth Engine (GEE) platform. Classification accuracy was assessed through field surveys and comparison with reference data derived from Google Earth. Furthermore, land use and land cover (LULC) change analysis was conducted for the period spanning 2018 to 2023 using Geographic Information Systems (GIS). Change detection analysis was performed by overlaying the annual classified datasets to identify areas of both persistence and change. The resulting land cover was categorized into six key classes relevant to the study area: natural water bodies (W1), mangrove forests (F3), aquaculture farms (A9), built-up areas (U2), agricultural areas (A0), and miscellaneous areas (M4). LULC changes were then summarized in a time series format to quantify and visualize the dynamics of land cover change.

Main Results : The integration of Google Earth Engine (GEE) with the Random Forest (RF) algorithm, a powerful machine learning classifier, significantly enhances the efficiency of mangrove forest change detection. Sentinel-2 satellite imagery, accessed through the Earth Engine Data Catalog, was processed using cloud computing resources, facilitating rapid and efficient analysis of extensive datasets. The land use and land cover classification achieved an overall accuracy exceeding 80% and a Kappa coefficient ranging from 0.6 to 0.8, based on 256 independent validation points strategically distributed across the study area. This validation, grounded in binomial probability theory, indicates an acceptable level of reliability for the classification results. The resulting data offer significant potential for effective mangrove resource management. The land use and land cover classification results showed the proportional distribution of land cover types in the study area. In 2018, mangrove forests constituted the largest proportion, covering 73.406% of the total area. This was followed by agricultural areas, which occupied 12.360%, natural water bodies at 1.803%, aquaculture areas at 7.278%, built-up areas at 0.873%, and finally, miscellaneous areas at 4.280%. By 2020, a notable shift in land cover was observed, with mangrove forest cover experiencing a decrease to 71.033%. This decrease was subsequently followed by a recovery, as mangrove forest cover increased to 72.300% by 2023. Analyzing the changes between 2018 and 2020 reveals a net loss of 2.373% in mangrove forest area. This loss was primarily attributed to the conversion of mangrove forest land into agricultural land, indicating a shift in land use practices within the study area. Conversely, the period from 2020 to 2023 witnessed a reversal of this trend, with mangrove forest area exhibiting a net increase of 1.267%. This increase can be primarily explained by the reconversion of agricultural land back into mangrove forests, suggesting a potential recovery or restoration of mangrove ecosystems.

Conclusions : The Google Earth Engine (GEE) platform facilitates the rapid online processing of satellite imagery, mitigating hardware limitations. However, the processing of very large datasets may necessitate segmentation into smaller tiles. For applications in other geographic regions, the definition of context-specific parameters and vegetation indices is crucial for achieving acceptable accuracy in land use and land cover classification. The findings of this study demonstrate the efficacy of GEE for monitoring changes in mangrove forest area over a six-year period. The observed expansion of mangrove forests between 2020 and 2023 can be attributed to the implementation of stricter governmental measures to prevent encroachment. This study represents a significant advancement in the application of satellite technology and geographic information systems (GIS) for mangrove forest conservation, offering a more cost-effective and time-efficient alternative to traditional field-based methods and enabling more efficient resource management. Furthermore, the developed methodology holds potential for future applications, such as estimating the carbon sequestration capacity of mangrove ecosystems.

Plant Community at Thachang Official Community Forest (Chaipattana Foundation) Chanthaburi Province

Benchawon Chiwapreecha — 2025-02-26

Background and Objectives : Chanthaburi is one of the economically significant provinces in the eastern region, particularly in agriculture, gem trading, and tourism. This has led to a large resident and floating population, resulting in urban congestion. However, it has been found that within the city district, which is the center of business and residence, there are community forests interspersed in the area, Thachang Community Forest (The Chaipattana Foundation) is an urban forest that plays an important role in human health and well-being. The problem arises from urban community expansion that is not in harmony with green spaces, which are essential for a high-quality urban life. This forest serves as the lungs of the city for the community, helping to reduce air pollution, sequester carbon, filter PM 2.5 dust, act as a reservoir for excess rainwater during the rainy season, and serve as a source for learning about local plant species. The objectives of this study were to analyze the species composition and forest structure, with the aim of developing a conservation plan and restoring degraded forest areas.

Methodology : This study examine plant communities in the Thachang Community Forest (The Chaipattana Foundation), which was formerly an abandoned rubber plantation, covering an area of approximately 18 rai, located in Tha Chang Subdistrict, Mueang District, Chanthaburi Province. The general characteristics are lowland plains interspersed with small freshwater swamp. Three permanent plots, each 20 x 50 meters, with each plot further divided into 30 sub-plots of 10 x 10 meters, were established in the study area. All trees with circumference of at least 14 cm were tagged, measured, and identified the types of plants found in the plot according to the Flora of Thailand. The scientific name were checked online from The Plant List. (http://www.theplantlist.org/). The importance value index, species diversity index, similarity and plant density were analysed. The implementation period was from November 2022 to September 2023.

Main Results : The results showed a total of 31 families, 35 genera, 45 species, and 4 unknown species. Fifteen species were classified as Restricted Wood type A including Vatica harmandiana Pierre, Garcinia speciosa Wall, Parkia speciosa Hassk, Anisoptera costata Korth, Parinari anamense Hance, Nephelium hypoleucum Kurz, Syzygium thorelii (Gagnep.) Merr. & L.M. Perry, Peltophorum dasyrrhachis (Miq.) Kurz, Cratoxylum formosum (Jack) Dyer, Dalbergia cochinchinensis Pierre, Diospyros ferrea (Willd.) Bakh., Lithocarpus annamensis A. Camus, Vitex pinnata L., Dillenia ovata Wall. ex Hook. f. & Thomson and Diospyros venosa Wall. ex A. DC. The tree layers were divided by height in the vertical direction into three levels: the upper canopy (20-23 meters), which includes Dipterocarpaceae species such as Anisoptera costata Korth. and Dipterocarpus baudii Korth. Below that is the understory (14-18 meters), which includes Vatica harmandiana, Parinari anamense, Artocarpus lakoocha Roxb., Diospyros venosa, Vitex pinnata, Knema globularia (Lam.) Warb., Garcinia cowa Roxb. ex Choisy, Acronychia pedunculata (L.) Mig., Garcinia speciosa Wall., Diospyros ferrea, Elaeocarpus robustus Roxb., Aporosa microstachya (Tul.) Mull.Arg., Peltophorum dasyrrhachis, Family Myrtaceae and Syzygium spp. The lower layer plants include Memecylon pauciflorum Blume, Melientha suavis Pierre and Melodorum fruticosum Lour. The replacement of tree species in the research area is complete at all levels, and the ground has accumulated organic matter from the shedding of leaves of certain deciduous trees (such as Hevea brasiliensis, Dalbergia cochinchinensis, Vatica harmandiana and Lagerstroemia duperreana). Some areas of the forest have characteristics of small freshwater swamps, thus supporting a community of peat swamp plants, including Calophyllum calaba, Syzygium thorelii and Ixora lobbii. Based on the importance value index (IVI), the dominant species were Hevea brasiliensis, Vatica harmandiana, Aporosa microstachya, Nephelium hypoleucum and Anisoptera costata, with IVI values of 79.17%, 42.24%, 21.46%, 20.1% and 13.25%, respectively. The species diversity index (H^/) was 2.84 with 63.62% of similarity value. While the tree density was 216 individual per Rai. The rubber trees have a total basal area of 152.39 square meters, indicating that the rubber trees in the area are large and dense, which slow down forest recovery by competing for growth factors. However, the survey found a small number of rubber tree saplings, possibly due to the lower competitive ability of rubber tree saplings compared to the saplings of local plants such as Vatica harmandiana, Aporosa microstachya, Nephelium hypoleucum, Lagerstroemia duperreana, Cratoxylum formosum, Calophyllum calaba and Melientha suavis, among others.

Conclusions : It was concluded that Thachang Community Forest is undergoing natural regeneration, with a diverse range of local plants thriving. The prominent species is Vatica harmandiana. The variety of plants found, such as Aporosa microstachya, Nephelium hypoleucum, Anisoptera costata, Cratoxylum formosum, Calophyllum calaba, Lithocarpus annamensis, Elaeocarpus robustus, Melodorum fruticosum and Melientha suavis will lead to the selection of species for planting alongside rubber trees, which continue to grow well in the area, to shorten the forest restoration period. This approach also serves as a guideline for managing the area to conserve local plants and improve the surroundings for the community’s recreational benefits.

Effect of Vitamin D3 Supplementary Shrimp Diet on Cuticle Formation of the Pacific White Shrimp (Litopenaeus vannamei)

Boonyarath Pratoomchat — 2025-03-03

Background and Objectives : The requirement of vit D₃ in form of 1,25-Dihydroxy-Vitamin D₃ (Calcitriol) for white shrimp (Litopenaeus vannamei) is still rather lacking in term of cuticular formation and mineralization due to the direct and indirect affect the success of molting, and subsequently affects the growth opportunity and survival rate. The study on effectiveness of vitamin D₃ in form of calcitriol to promote the shrimp exoskeleton in terms of ions content in cuticle and cuticular structure of L. vannamei were investigated to further decide the optimal level of vit D₃ in a practical diet be part of effectiveness to increase the shrimp production of Thailand.

Methodology : The three treatments followed by the concentrations of vitamin D₃ (AcD) at 100 mg (AcD100), 150 mg (AcD150) and 200 mg (AcD200) vit D₃ kg^-1 diet and without AcD (Control) were designed with three replications using completely randomized design (CRD). Three replications were used in the study. The healthy L. vannamei juvenile aged 45 days with 12.50 ± 0.65 g in body weight and 9.90 ± 0.50 cm in total length from intensive pond of private sector were previously acclimated during 10 days in laboratory before sampling to the 500L experimental circular fiberglass tank with 1.05 m in diameter. The experimental shrimps were held in 25 ppt medium at 70 ind./m². Water was exchanged with debris every week and exchanged by 50% of cleaned water. Experimental shrimps were fed the experimental diets which was formulated to satisfy the nutritional requirement of L. vannamei with the isonitrogenous (38.15% crude protein) and isolipidic (7.6% crude lipid which stored in individual bag at 4°C in refrigerator for the whole trial duration. The ration of 5% in total wet weight and four times daily (08.00 am, 01.00 pm, 05.00 pm and 09.00 pm) were operated for 30 cultured days. Water quality parameters as salinity, temperature, dissolved oxygen (DO), alkalinity, nitrite and ammonia were monitored every week at 09.00 am and 03.00 pm. To controlled sunlight and temperature, blue coloured plastic covered the tank. At termination, the experimental shrimps at B (Postmolt) and Do (Early Premolt) stages (10 samples/replication) were individually sampled for examining ions and cuticular structure as cuticle thickness and number of layers within cuticle using carapace near the posterior rostral ridge using scanning electron microscopy (SEM) coupled with energy dispersive x-ray spectroscopy. The combination of SEM and EDS allows for the analysis of both the quantity of X-rays emitted and their energy, enabling the identification and quantification of chemical elements present at detectable concentrations in percentage by weight. Analysis of variance with one-way ANOVA and Duncan’s New multiple range test using SPSS software were used for statistically different the results among treatments. The level of significant difference was set at p< 0.05.

Main Results : The results found that cuticle thickness and number of layers of shrimp cuticle at B (45.2 ± 2.9 m and 25.5 ± 1.9 layers) and Do stage (97.5 ± 8.4 m and 69.4 ± 4.9 layers) of AcD200 group were the most significant highest (p<0.05), followed by AcD150 group with non-significant difference (p>0.05) for Do stage, which corresponded with higher percentage of Ca (11.23 ± 0.42%), Mg (0.65 ± 0.09%), Mn (0.71 ± 0.13%) and P (5.32 ± 0.87%) in cuticle at B molt stage (p<0.05) and Ca (13.23 ± 0.31%), C (56.13 ± 4.35%) and O (34.34 ± 2.15%) in cuticle at Do molt stage (p<0.05). The thickness and number of layers of cuticle at B and Do stages of AcD 150 and AcD100 groups were not significant different (p>0.05) but their values of both groups were significantly higher than that of control (p<0.05). The percentages of Cu, K, Na, O, C and Cl of shrimp cuticle at B molt stage and the percentages of Cu, K, Na, Mg, Mn and Cl of shrimp cuticle at Do molt stage were not significantly different (p>0.05) among groups respectively. All parameters of water quality as salinity, temperature, DO, alkalinity, nitrite and ammonia among the treatments were not significantly different (p> 0.05) and their values were acceptable for shrimp throughout the experimental period.

Conclusions : Finally, the research results demonstrate the supplementation of at levels of 150-200 mg kg^-1 in diet for raising L. vannamei shrimp is the most suitable to contributes the higher mineralization rate of Ca, Mg and Mn in form of phosphate for post molt stage and carbonate form for intermolt stage to faster process of cuticle formation. It is high possibility that vit D₃ can improve the regulation of Ca and P metabolism and absorption to promote the early mineralization of postmolt cuticle led to the suprior nucleation of Ca and CO₃^-to better formation of the intermolt cuticle. These results highlight the benefits of supplementing the suitable concentration of vit D₃ in term of precision nutrition to support the cuticle formation in L. vannamei shrimp results in the higher growth performance and survival rate.

Effects of Heat and Ultra-Sonic Processing on Some Qualities of Ma-Kiang (Cleistocalyx nervosum var. paniala) Juice

Supawat Namkham — 2025-03-03

Background and Objectives : Cleistocalyx nervosum var. paniala, commonly known as “Ma-Kiang” in Thailand, belongs to the family Myrtaceae. This plant is a small to medium-sized tree found in tropical and subtropical regions, particularly in Southeast Asia. It has gained attention for its edible fruits and bioactive compounds, which are associated with various health benefits. Its fruits and extracts hold promise in health applications, particularly as natural antioxidants and anti-inflammatory agents. Ultra-sonic processing involves the use of high-frequency sound waves (20 kHz to several MHz) to generate intense pressure waves within a liquid medium. This technique has found significant applications in food processing, including fruit juice production, due to its ability to improve extraction, enhance flavor, and promote better preservation. The intense shear forces and heat generated during ultrasonication can also inactivate microorganisms (bacteria, yeasts, and molds) in fruit juices, improving the microbiological quality and extending shelf life. This, however, depends on the intensity, duration, and frequency of the ultrasound treatment. Ultra-sonic processing is considered another option for fruit juice processing, as it is a novel technology that can better preserve the bioactive compounds and antioxidant efficiency of the juice compared to heat processing. Therefore, this research aimed to investigate the effects of ultra-sonic processing on various qualities of Ma-Kiang juice compared to heat processing.

Methodology : To prepare Ma-Kiang juice, fresh Ma-Kiang fruits were harvested, washed and drained before refrigeration at 6ºC for 2 h before processing. The extraction of Ma-Kiang juice was done by extracting the Ma-Kiang fruits using a juicer extractor. Total soluble solids of the extracted juice were adjusted to 16ºBrix with fructose. Ma-Kiang juice was processed using a High Intensity Ultra-Sonic Processor with a frequency of 25 kHz and 20–80% amplitude for 30 min and heated at 80ºC for 2 min, then immediately cool it by immersing it in an ice-water bath for 5 min. All processed samples were stored at 4ºC prior to analyzing their qualities. Physico-chemical qualities of the treated samples including color parameter, viz. L (brightness), a* (redness/greenness), b*(yellowness/blueness), C* (chroma) and total different colors (∆E), viscosity, total soluble solids, pH and total titratable acidity (TTA) were investigated. To study the health benefits, total anthocyanin content, total phenolic compounds, and antioxidant capacity, viz. 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activity, ferric-reducing antioxidant power (FRAP), and 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS⁺) radical scavenging activity were also assessed. Polyphenol oxidase (PPO) and peroxidase (POD) activities in the samples were monitored, and the residual of both enzymes were then calculated. According to the Thai Community Product Standard for Ma-Kiang juice (TCPS. 484/2014), some indicator microorganisms, viz. total plate counts, yeasts and molds, coliform bacteria, Escherichia coli, Salmonella, Staphylococcus aureus, Bacillus cereus and Clostridium perfringens, were determined.

Main Results : From the experimental results, it was found that the brightness value (L) of the processed Ma-Kiang juice decreased after being treated with heat and high-frequency sound waves compared to fresh Ma-Kiang juice (control). It was noticed that when the intensity levels of the ultrasonic frequency increased, the L values of the samples significantly decreased. The heated Ma-Kiang juice had the lowest redness (a*) and the highest yellowness (b*). For ultrasonic treated samples, the a* and b* values tended to increase when the frequency intensity levels rose, which correlated with the values of color intensity (C*) and total different colors (∆E) in the samples. The viscosity, total soluble solids, pH, and total titratable acidity of the processed Ma-Kiang juice using heat and ultra-sonic processing at different frequency intensity levels showed no statistically significant differences when compared to the unprocessed samples. Samples processed with ultrasonication still retained high levels of bioactive compounds (total anthocyanins and total phenolic compounds) and antioxidant capacity (DPPH, FRAP, and ABTS^•+ assays) compared to fresh samples, and they contained more than that processed by heat. The activities of polyphenol oxidase and peroxidase in the samples decreased after processing. Additionally, it was found that heat processing at a temperature of 80ºC for 2 min and ultrasonication at an intensity level of 80% could inhibit indicator microorganisms related to the sanitation and safe consumption of Ma-Kiang juice, bringing their numbers below the standards set by the Thai Community Product Standard (TCPS. 484/2014).

Conclusions : From this experimental research, it can be summarized that processing Ma-Kiang juice with ultra-sonication at kHz, with an intensity level of 80% for 20 minutes, was the most optimal condition. This method can better preserve various qualities and bioactive compounds, as well as the antioxidant efficiency of the product, compared to processing under other conditions. Additionally, it can be suggested that ultra-sonic processing was another option for fruit juice processing and can be commercially utilized. For future research, sensory evaluation may be required before the technology is further developed industrially, and the effects of ultra-sonic processing on the shelf life and other bioactive compounds in Ma-Kiang juice should also be studied.

Effects of pH Adjustment in Wastewater on the Efficiency of Local Aquatic Plants in Treating Wastewater from a Household-Scale Rice Noodle (Khanom Jeen) Factory

Angsuma Kanchak — 2025-03-10

Background and Objectives : The wastewater generated from a Khanom Jeen (fermented rice noodles) factory is characterized by its turbid milky white appearance and sour odor, which results from the presence of organic matter derived from the fermentation of starch during noodle processing. As a result, this wastewater exhibits high acidity, with a pH ranging from 3.25 to 3.56, that affect human health including environmental problems. Therefore, the objectives of this study were to investigate the effects of pH adjustment and non-adjustment on the efficiency of three locally available aquatic plants, i.e. water hyacinth, umbrella plant, and canna- in treating wastewater from Khanom Jeen production. The ultimate goal is to explore an effective and cost-efficient wastewater treatment system suitable for household-scale implementation, thereby promoting sustainable wastewater management practices.

Methodology : The study was conducted using experimental wastewater treatment ponds constructed from cement tanks with dimensions of 25 cm in width, 25 cm in height, and 60 cm in length. Each ponds was filled with gravel and planting soil. The plants were pre-cultivated to ensure root stabilization and new shoot (sprout) growth before employing in the experiments. Features of each plant type, i.e., size, height, stem, and 50 cm root length approximately, and 0.5 kg (wet basis) each were considered. The study was divided into two experimental setups. In the first setup, the wastewater pH was adjusted to neutral condition (pH 7) by using lime (Cao), and compared with untreated acidic wastewater. This setup consisting of four treatments, i.e., a control pond (no plant cultivation), a pond with water hyacinth, a pond with umbrella plant, and a pond with canna. Each treatment contained 10 liters of wastewater, and the periods retained at 3, 5, and 7 days. As for the second set, the experiment of a sequential wastewater treatment system was utilized with different aquatic plant species in each treatment, comprising a wastewater holding tank, a pond with umbrella plant, a pond with canna, and a final effluent storage pond. The system was operated continuously for 15 days, treating 20 liters per day of wastewater at a flow rate of 14 mL/min and a retention time of 24 hours per pond. Sampling of influent and effluent wastewater were collected, and were analyzed of key water quality parameters, including pH, total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), and phosphate (PO₄³⁻). Mean values, standard deviation, and F-test (One-way Anova Analysis) comparisons were statistics for analysis. The mean difference of plant remediation efficiency in wastewater treatment conditions was compared by using Least Significant Difference (LSD) at a 0.05 significance level.

Results : For the first experimental set, found that the three local aquatic plant species, i.e. water hyacinth, umbrella plant, and canna were demonstrated significant efficiency in reducing total suspended solids, biochemical oxygen demand, and phosphate across the three retention periods (3, 5, and 7 days). In the pH-adjusted condition, removal efficiencies ranged from 88.66% to 97.34% for TSS, 72.33% to 85.47% for BOD, and 6.23% to 35.48% for phosphate. In the non-adjusted condition, the corresponding removal efficiencies were 82.40% to 96.62% for TSS, 74.31% to 85.47% for BOD, and 8.90% to 69.41% for phosphate. Among the three species, umbrella plant exhibited the highest treatment efficiency under both conditions, with average efficiencies of 66.78% (pH-adjusted) and 71.63% (non-adjusted). A significant difference (p<0.05) in treatment efficiency was observed between pH-adjusted and non-adjusted conditions, with all plant species performing significantly better than the control (no plants). In the second setup, daily variations influent water quality were observed. As wastewater passed through the plant-based treatment system, all measured parameters showed a reduction except for pH, which increased. The treatment efficiencies for TSS, BOD, COD, total nitrogen, and phosphate were 86.96%, 57.33%, 76.24%, 48.98%, and 24.04%, respectively. The system achieved removal efficiencies of 86.96% for SS, 57.33% for BOD, 76.24% for COD, 48.98% for TN, and 24.04% for phosphate.

Conclusions: This study demonstrates the potential of utilizing locally available aquatic plant species, particularly umbrella plant and canna, for effective wastewater treatment. These plants significantly reduced total suspended solids, organic pollutants, including BOD, COD, total nitrogen, and phosphate concentrations in wastewater from a Khanom Jeen factory. Furthermore, a notable increase in pH was observed after treatment in all experiments, suggesting an improvement in wastewater acidity. The initial pH of the influent ranged from 2.93 to 3.31, with an average of 3.05, whereas the treated effluent had an increased pH range of 3.44 to 4.80, with an average of 3.99. The use of these plant species in a low-cost, sustainable treatment system offers a viable solution for managing acidic wastewater in small-scale and household settings, thereby contributing to improved environmental and public health outcomes. Future research should explore long-term performance, the potential for nutrient recovery, and the feasibility of scaling up this treatment approach for larger wastewater volumes.

Quality Changes and Lactobacillus casei 01 Survivability in Milk and Maoberry Mousse Products Supplemented with Inulin during Refrigerated Storage

Jaratsinee Suweeranon — 2025-03-10

Background and Objectives : Mousse is a light and airy dessert made by incorporating air into a mixture of whipped cream, egg whites, or gelatin, creating a smooth and fluffy texture. It can be sweet or savory, with popular variations including chocolate and fruits. Maoberry or Mao-Luang (Antidesma bunius) is a tropical fruit rich in bioactive compounds, including antioxidants, flavonoids, and phenolic acids. Scientifically, it has been shown to exhibit anti-inflammatory, antimicrobial, and cardioprotective properties. The fruit supports digestive health, regulates blood sugar levels, and enhances immune function due to its high vitamin and mineral content. Inulin is a natural prebiotic fiber found in plants like chicory root, garlic, and onions, scientifically recognized for promoting gut health by stimulating beneficial bacteria growth. It aids digestion, improves bowel regularity, and enhances nutrient absorption. Inulin also supports metabolic health by regulating blood sugar levels. Additionally, its ability to increase satiety helps with weight management and appetite control. Probiotics are live microorganisms, primarily bacteria and yeasts, which provide health benefits when consumed in adequate amounts. They mainly belong to genera Lactobacillus and Bifidobacterium. Probiotics offer numerous health benefits by promoting gut health, enhancing digestion, and strengthening the immune system. They play a vital role in preventing gastrointestinal disorders and aiding in weight management. Regular consumption of probiotics through foods or beverages can significantly enhance overall well-being. Thus, this research aimed to investigate the changes in qualities and the survival rate of probiotic Lactobacillus casei 01 in milk and maoberry mousses supplemented with inulin during refrigerated storage at 4ºC for 12 days.

Methodology : Probiotic-mousse formulas, including milk mousse, milk mousse supplemented with inulin, maoberry mousse, and maoberry mousse supplemented with inulin, were produced and were then refrigerated stored at 4ºC for 12 days. The samples were taken every 3 days for quality assessments in various aspects, viz. physical (color parameters and firmness), chemical (total soluble solids, pH, and total titratable acidity), and microbiological qualities. Amounts of bioactive compounds (ascorbic acid, total anthocyanins, and total polyphenolic compounds) and antioxidant activity (DPPH and FRAP assays) were investigated. The survival rates of probiotic L. casei 01 in the samples were also monitored.

Main Results : From the experimental results, it was found that anthocyanins, which were the main pigments found in maoberry, affected the color values (L, a*, and b*) of the mousse samples. However, the addition of inulin did not affect the color values of the samples. It was also found that maoberry mousses had lower firmness and pH values than the milk mousses. The addition of inulin did not affect the texture and pH values of the mousses. Additionally, it was found that maoberry mousses had higher levels of ascorbic acid, total anthocyanins, and total polyphenolic compounds, as well as higher antioxidant activity (DPPH and FRAP assays), than the milk mousses. During storage the samples in a refrigerator at 4ºC for 12 days, it was found that the addition of maoberry pulp had a greater effect on color changes than the addition of inulin. Color changes in maoberry mousses were primarily due to the degradation of anthocyanins. The firmness of the samples increased from the first day of storage, especially in milk mousse supplemented with inulin. It was also found that total soluble solids in all samples remained unchanged, but pH value slightly decreased. Amounts of ascorbic acid, total anthocyanins, and total polyphenolic compounds, as well as antioxidant activity, decreased during the refrigerated storage. However, maoberry mousses maintained higher levels of bioactive compounds and antioxidant activity compared to the other. This research also highlighted the role of inulin in increasing the survival rate of probiotic L. casei 01 during storage. The numbers of L. casei 01 in mousses supplemented with inulin remained above 6 log CFU/g after 12 days of storage. In contrast, the numbers of L. casei 01 in mousses without inulin addition decreased to below 6 log CFU/g within the storage period. It was evident that the numbers of L. casei 01 in both milk and maoberry mousses supplemented with inulin met the probiotic standard, which should have a count of at least 6 - 7 log CFU/g in food before consumption. Furthermore, the analysis of total plate counts, yeasts-molds, coliforms, and various pathogenic microorganisms, viz. Escherichia coli, Listeria monocytogenes, Salmonella, and Staphylococcus aureus, in all samples during storage, found that the numbers of all microbial groups remained below the dairy product standards.

Conclusions : Overall, this research found that t ingredients used in the production of mousses affected various quality aspects of the products during refrigerated storage (4ºC). Maoberry significantly impacted the color parameters, firmness, and pH, as well as the amounts of bioactive compounds and antioxidant capacity of the samples. Inulin affected the texture and helped increase the survival rate of L. casei 01. After 12 days of storage, the numbers of various indicator microorganisms remained within the standards for dairy products, ensuring consumer safety.

Impact of Osmotic Dehydration Techniques on Mass Transfer, Physicochemical and Antioxidant Properties of Osmotically Dehydrated Mango Slices

Kulab Sittisuanjik — 2025-03-12

Background and Objectives : Mango (Mangifera indica L.) is a tropical fruit with a unique color, aroma, and taste. It is rich in nutrients that benefit health, including carbohydrates, proteins, dietary fiber, vitamins, and minerals. Additionally, it contains important bioactive compounds such as phenolic acids, flavonoids, and carotenoids (Gupta et al., 2022). However, mangoes have a high moisture content, making them highly perishable after harvest. Excess mango production beyond market demand impacts production costs. Processing mangoes into dried fruit products is an alternative that adds value and extends shelf life. Nevertheless, hot-air drying methods have the drawback of being time-consuming, which negatively affects the product quality. The pretreatment method of mangoes before drying, such as osmotic dehydration, can reduce drying time. Osmotic dehydration is a method that involves soaking fruits or vegetables in a solution to remove water from them. This process reduces moisture content and water activity (a_w), which inhibits the growth of microorganisms responsible for food spoilage. It also Improve the physicochemical and sensory qualities, as well as extend the shelf life of fruits and vegetables. However, conventional osmotic dehydration methods take a long time. The application of non-thermal and environmentally friendly technologies, such as ultrasound and vacuum impregnation combined with osmotic dehydration, can enhance mass transfer efficiency, allowing water to be removed from the raw material more quickly while also improving the quality of the food material. The ultrasound technique induces cavitation, leading to microstructural changes in fruit tissue, which facilitates the movement of water and solutes (Trusinska et al., 2024). Meanwhile, vacuum conditions help eliminate gases in the intercellular spaces using a hydrodynamic mechanism, allowing solutions to impregnate the pores of the plant structure (Gautam et al., 2024). Thus, this study aims to investigate the effects of ultrasound and vacuum combined with osmotic dehydration on mass transfer, physicochemical properties, and antioxidant activity in mango slices.

Methodology : The preparation of Kaew Kamin mango for the osmotic dehydration study begins with slicing the mango lengthwise into pieces approximately 1 cm thick. The mango slices were soaked in a 0.5% calcium chloride solution to enhance firmness and then blanched in boiling water at 100°C for 30 seconds to help preserve color quality. Mango slices were pretreated using four osmotic dehydration techniques: traditional osmotic dehydration (OD), vacuum-assisted osmotic dehydration (VOD), ultrasound-assisted osmotic dehydration (USOD), and ultrasonic-assisted vacuum osmotic dehydration (USVOD). The mango slices were soaked in 60° Brix sorbitol solution at 1:3 mango to solution ratio for 8 hours. The study was conducted under vacuum conditions in a vacuum chamber with a pump (Gast model DOA-P504-BN Labmodel, Germany) at 150 mbar. For ultrasound pretreatment, a high-intensity ultrasonic processor (Sonics Vibra-Cell VCX-500, USA) with 500 watts and 20 kHz was used. Water loss (WL), solid gain (SG), weight reduction (WR), moisture content, and water activity were measured at various time intervals (2, 4, 6, and 8 hours). At the end of the osmotic dehydration process (after 8 hours), color (L*, a*, b*, and E), total soluble solids, pH, titratable acidity, total carotenoid content, total phenolic content, and antioxidant activity (using the DPPH method) were analyzed. The experiment was conducted using a completely randomized design (CRD). The experimental data were analyzed using analysis of variance (ANOVA), and significant differences between mean value of treatments were determined using Duncan’s Multiple Range Test (DMRT)at a 95% confidence level with SPSS for Windows. All experiments were repeated three times.

Main Results : The osmotic dehydration techniques, including OD, VOD, USOD, and USVOD significantly affected the mass transfer parameters, physicochemical and antioxidant properties of osmotically dehydrated mango slices.The experimental results showed that the USVOD technique effectively accelerated mass transfer in the osmosis process. At the end of the process, the mango slices exhibited the highest water loss and solid gain, reaching 68.09% and 19.56%, respectively. Meanwhile, the moisture content and water activity showed the greatest reduction, with values of 41.70% and 0.8773, respectively, when compared to other techniques. The study on the physicochemical properties of osmotically dehydrated mango after 8 hours revealed that the use of the USVOD technique resulted in the highest total soluble solids and pH values. Whereas the titratable acidity, lightness (L), greenness (-a), yellowness (b*), and color difference (E) were at their lowest. Additionally, the USVOD technique resulted in higher total carotenoid content, total phenolic content, and DPPH radical scavenging activity, compared to all other techniques used in the study.

Conclusions : Osmotic dehydration techniques affect the quality of osmotically dehydrated mango slices in terms of mass transfer, physicochemical and antioxidant properties. The application of the USVOD technique improves mass transfer efficiency by increasing water loss and solid gain, while reducing moisture content and water activity to the maximum. Additionally, mango slices pretreated with the USVOD technique resulted in the highest total soluble solid content, pH values, antioxidant activity, and bioactive compounds, including total carotenoid content and total phenolic compounds, while exhibiting the lowest E value. It can be concluded that the USVOD technique is a non-thermal and environmentally friendly technology that can be applied to raw material preparation to enhance efficiency in commercial drying processes. It reduces energy consumption, processing time, and production costs while preserving the nutritional value of the products.

Microplastic Contamination in Fish and Fermented Fish Paste in the Thale Noi Area: Analysis and Mitigation Approaches

Peeranart Kiddee — 2025-03-26

Background and Objectives: The Thale Noi area is a significant eco-tourism destination in Phatthalung Province, attracting many tourists. Additionally, many households reside around Thale Noi, leading to substantial waste generation from both domestic activities and tourism. This waste can enter nearby water sources, where plastic waste may gradually degrade into microplastics. Microplastics are small plastic particles with a diameter of fewer than 5 millimeters. They can contaminate ecosystems and negatively affect the quality of local community products, particularly traditional food items. Thale Noi is a vital wetland area that serves as a water catchment and supports tourism, fishing, and agriculture. The local community relies on fish from Thale Noi to produce various products, particularly fermented fish paste, locally known as "kapi pla". Since whole fish are used in the production process, there is a potential risk of microplastic contamination. Fermented fish paste is a highly popular product among both locals and tourists. This study investigates microplastic contamination in fish commonly used for fermented fish paste production, microplastic contamination in the fermented fish paste itself, and the production process of fermented fish paste. The objective is to develop guidelines for improving production methods to minimize microplastic contamination, ensuring safer products. This will enhance the safety and quality of fermented fish paste from Thale Noi, adding value to this important local product in the future.

Methodology : The study of microplastic contamination in fish and fermented fish paste, as well as the production process of fermented fish paste in the Thale Noi area, was exploratory research combined with laboratory analysis. Fish samples were collected from five species commonly used by local communities to produce fermented fish paste: Trichogaster trichopterus, Puntius gonionotus, Trichogaster pectoralis, Barbodes schwanenfeldi, and Pristolepis fasciata, with 60 samples per species. For the study of microplastic contamination in fermented fish paste, samples were randomly purchased, and data were obtained from five producers, with three samples per producer. Data collection was conducted every two months for fish and fermented fish paste, resulting in 1,800 fish samples and 90 fermented fish paste samples. Fish and fermented fish paste samples were prepared for further analysis to determine the microplastics' quantity, color, and shape, contaminating both fish and fermented fish paste. Additionally, the production process of fermented fish paste was studied, focusing on key processes such as the main fish species used, equipment for chopping fish, tools for fermenting fish paste, tools for grinding or mincing fish, drying equipment, fermentation duration, drying duration, and containers for storing fermented fish paste. Data analysis was conducted to compare differences in the amount of microplastic contamination between fish species and between microplastic contamination in fermented fish paste and various production methods. The One-Way ANOVA method was used, followed by the Duncan multiple range test to compare differences across fish species and production processes at a significance level of 0.05. Data analysis was performed using Microsoft Excel. The study aimed to identify the fish species with the lowest microplastic contamination as a recommendation for selecting raw materials for fermented fish paste production.

Main Results : The fermented fish paste was found to have an average microplastic contamination of 115.0 ± 119.7 pieces/kg. Among the fish species commonly used as raw materials for fermented fish paste production, Puntius gonionotus exhibited the highest microplastic contamination, averaging 365.5 ± 276.0 pieces/kg, followed by Barbodes schwanenfeldi with an average of 321.8 ± 224.1 pieces/kg. The lowest level of microplastic contamination was observed in Trichogaster pectoralis at an average of 162.2 ± 108.0 pieces/kg. A comparison of microplastic contamination among the five fish species using One-Way ANOVA at a significance level of 0.05 revealed statistically significant differences. Post hoc analysis showed that most fish species exhibited significantly different levels of microplastic contamination at the 0.05 significance level, except for the following pairs, where no significant difference was observed: Trichogaster trichopterus and Trichogaster pectoralis, Puntius gonionotus and Barbodes schwanenfeldi, Puntius gonionotus and Pristolepis fasciata, and Barbodes schwanenfeldi and Pristolepis fasciata. Additionally, smaller fish were found to have higher levels of microplastic contamination compared to larger fish, particularly in Puntius gonionotus, Trichogaster pectoralis, Barbodes schwanenfeldi, and Pristolepis fasciata. Black-colored microplastics and fiber-shaped microplastics were the most prevalent contaminants in both fish and fermented fish paste. Furthermore, the equipment used in the production process of fermented fish paste significantly influenced microplastic contamination levels. Specifically, equipment used for chopping, fermenting, and drying the fermented fish paste contributed to higher microplastic contamination. The use of plastic equipment in these processes resulted in significantly higher microplastic contamination at a confidence level of 0.1.

Conclusions : To reduce microplastic contamination in fish paste and improve processing methods, it is recommended to select fish species used as raw materials carefully. Puntius goionotus, Barbodes schwanenfeldi, and small fish should be avoided. Production equipment should be made from wood or other non-plastic materials to minimize contamination. Avoiding the use of plastic tools in the production process will help reduce microplastic contamination, thereby enhancing the safety and quality of local food products.