Download Latest Complete Journal - JST Vol. 27 (S1). 2019
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1
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(Downloads: 44)
Abstract (Viewed: 8)Jackfruit straws are normally disposed as waste by food industries and vendors which may lead to serious environmental issue. In order to reduce the wastage and negative effects to the environment, jackfruit straw waste generated by jackfruit (Artocarpus heterophyllus) shows potential as bio-based film incorporated with starch. This work describes the effect of different starch and plasticizer contents on mechanical and thermal properties of jackfruit straw powder (JSP)/starch films. Film-forming solutions were prepared and cast by mixing JSP with tapioca starch at different ratios and for the plasticized films, ca. 15 - 40% of plasticizers including sorbitol and glycerol were incorporated into the JSP/starch films respectively. The tensile strength and modulus of JSP/starch films pronouncedly increased with increasing starch content, accompanied with a slight decreasing in the elongation at break. The result demonstrated that starch interacted with JSP, resulting in the formation of a new network to improve the properties of JSP films. FTIR spectrum analyses demonstrated the presence of hydrogen bonding in the JSP/starch film. The tensile strength of the plasticized JSP/starch films decreased with increasing sorbitol and glycerol content from 15% to 40%. However, the plasticizing effect of sorbitol became more significant than glycerol, particularly on the tensile properties and thermal stability. Thermal analysis by thermogravimetric showed an increment in the decomposition temperature with the addition of plasticizers into JSP/starch films. The results suggest that films containing JSP and starch have the potential for the development of edible food packaging materials.Edible films, jackfruit straw, tapioca starch, tensile properties, thermogravimetric analysis
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(Downloads: 34)
Abstract (Viewed: 18)The current study investigates the phytochemical composition of Malaysian stingless bee honey (Kelulut honey-KH), which consists of total phenolic (TPC) and total flavonoid content (TFC), and antioxidant activity. The honey was collected from five different regions in Malaysia i.e. south, central, eastern, northern and east coast regions. TPC and TFC were quantified by using Folin-Ciocalteu and the aluminum chloride colorimetric techniques, respectively. The antioxidant activity was investigated using two methods: 1) 1,1-diphenyl- 2-picrylhydrazyl (DPPH) radical scavenging assay; 2) ferric reducing/antioxidant power assay (FRAP). The findings indicated that there were significant differences in phytochemical compositions and antioxidant activities of KH between different regions. This implies that geographical location, as well as cultivation and treatment processes, have significant effects on the KH quality.Kelulut honey, stingless bee honey, trigona spp, total phenolic content, total flavonoid content, antioxidant
3
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(Downloads: 21)
Abstract (Viewed: 8)The study was carried out to evaluate the impact of gamma irradiation on the physical parameters, microbial safety and the total polyphenolic content (TPPC) of Ceylon black tea (Camellia sinensis L.). Commercially available Broken Orange Pekoe Fannings (BOPF) black tea samples of 5 distinct brands (n=120) were irradiated at 0, 1, 2, 5, 10 and 30KGy doses using Co-60 gamma irradiator. Samples were analyzed for water activity (aw), color of tea and tea infusion, microbial safety and TPPC. Water activities of samples were within the range of 0.32 to 0.58 and no effect had been observed due to the irradiation. The mean value of L, b and E hunter parameters of tea infusion was increased where the "a" value was decreased with the increment of irradiation dose when compared to the control sample. High irradiation doses resulted in darker color of the tea infusion. Irradiated samples showed a significant reduction of the total plate count. After 5kGy dose, irradiated samples were in sterilized condition. Yeast and mould counts were gradually decreased with the irradiation dose. TPPC of tea leaves of both irradiated and non-irradiated samples ranged from 9.17- 37.98 GAE/240 ml and TPPC values were increased with the irradiation dose. Results conclude that 5kGy is the optimum dose for the effective microbial safety, preserving the physical parameters and TPPC of commercially available Ceylon black tea.Ceylon black tea, color of tea, irradiation, microbial safety, physical parameters, total polyphenolic content
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(Downloads: 15)
Abstract (Viewed: 3)In the present research, microalgae protein hydrolysate of Nannochloropsis gaditana (MPH) was extracted via enzymatic hydrolysis using alcalase enzyme. Hydrolysis conditions like (pH, temperature, enzyme concentration and substrate concentration) were optimized by Response Surface Methodology (RSM) using Central Composite Design (CCD). Four range of independent variables namely; pH (7-9), temperature (45-55°C), substrate concentration (2-6 g/L) and enzyme concentration (0.2-0.4 g/L) were used to study the influence of these parameters on the degree of hydrolysis. The CCD consisted of twenty-four experimental points and six replicates of central points with the optimum conditions obtained from this experiment were at pH 8.14, a temperature 51.4°C, a substrate concentration 5.48 g/L and an enzyme concentration 0.26 g/L with maximum degree hydrolysis of 55.76%. All experiments were fixed at 24 hours reaction time. The degree of hydrolysis of MPH was analysed using O-phthaldehyde (OPA) method to quantify the cleavage of peptide bond. The optimized sample was evaluated for its antioxidant activity using 1,1-Diphenyl-2-picrylhydrazyl (DPPH) assay with 52.19% and 2, 2'- azino-bis (ethylbenzthiazoline-6-sulfonic acid (ABTS) assay with 14.13%. The bioactive peptides contained in Nannochloropsis gaditana have the ability to scavenge free radicals and act as good antioxidantsAntioxidant, bioactive peptide, degree hydrolysis, microalgae, optimization
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(Downloads: 13)
Abstract (Viewed: 4)Pomelo pomace (PP) from Malaysia Tambun White (PO52) variety, dried at different temperature under vacuum condition were evaluated. PP was obtained after extraction process and contained high moisture content (MC). Dried PP can be used as an alternative to livestock feed, hence, dried concentrated form was preferable. Nevertheless, drying process significantly affects the physico-chemical properties of a dried product. Therefore, the present study was carried out to discover the effects of drying temperature on the physico-chemical properties (MC, pH, vitamin C, browning index (BI) and total color change) of PP. The PP was dried at different drying temperature (50, 60, 70, 80 and 90°C) using a vacuum drying (VD) oven for 24 hr. The freeze drying (FD) process was used as a control. The result showed the MC gradually decreased with increasing drying temperature, of which similar trend was also observed for the water activity and total soluble solids (TSS). In contrast, pH showed increment in value with elevated drying temperature. Interestingly, at 90°C, vitamin C of VD (30.38 mg / 100 g DW) was higher than FD pomelo pomace (21.10 mg / 100 g DW). BI significantly increased as temperature increased. However, no significant changes were observed for total color change after VD. In conclusion, VD at 90°C showed the most recommended temperature because the composition of quality properties at this temperature was not significantly varied with control. These fundamentals information of pomelo pomace could be the guideline for postharvest technologist and food processing manufacturers for various applications.Malaysian tambun pomelo, pomelo pomace, quality, temperature, vacuum drying
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(Downloads: 10)
Abstract (Viewed: 3)Modification of tilapia by-products (TB) into fish protein hydrolysate (FPH) using enzymatic treatment is a favorable approach for enhancing their values and applications in the food industry. The TB protein hydrolysate has a wide range of sizes, which is possible to be fractionated using ultrafiltration (UF) membrane for obtaining small sized peptides. Thus, the present study aims to assess the flux reduction behavior of ultrafiltration membrane by varying transmembrane pressure, stirring speed and solution pH. Regenerated cellulose membrane of 10 kDa molecular weight cut-off (MWCO) was used throughout of the study. It was found that the trends for flux behavior of all parameters were reaching steady state within 60 – 70 minutes. At completion of filtration (at 70 minutes), the highest permeate flux for each operating and physicochemical parameters were at 3 bar (13.6 L/m2h), 600 rpm (42.8 L/m2h) and pH 8 (53.4 L/m2h). In term of protein rejections, significant effects were attained for stirring speeds with reduction of 57% from 0 to 600 rpm and lowest protein rejection (9.6%) was obtained at pH 8. Thus, controlling the operating parameters of the UF process could reduce membrane fouling.Fish protein hydrolysate, flux reduction, protein hydrolysate, protein rejection, tilapia by-product, ultrafiltration
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(Downloads: 18)
Abstract (Viewed: 5)One of the most harmful greenhouse insect pests is the Trialeurodes vaporariorum or most commonly known as the greenhouse whitefly. The easiest way to monitor the population of greenhouse whiteflies is by the use of yellow sticky paper traps. The insect count information from the traps can be used for analyzing insect behavior by constructing biological models. In this work, stochastic models describing the effects of temperature and the time of day on the flight behavior of greenhouse whiteflies were developed. Sticky paper images and temperature data were collected from an organic tomato seedling greenhouse by using integrated wireless imaging and environmental sensors. The greenhouse whitefly counts were determined by processing the images using an insect counting algorithm. From the results obtained, differences between the flight rates of the greenhouse whiteflies for different ranges of temperature were observed. The relationship was shown to be best fit using a double Weibull distribution function with an r2 of 0.988 and mean squared error of prediction (MSEP) of 0.001. Using the model, it was found that the optimal temperature for flight of greenhouse whiteflies was around 20-26°C. From the real-time counting data, different daily peak flight times were discovered. The peak flight rates were modeled using multi-peak probability distribution functions where it shows that the multi-peak Gaussian distribution has the best fit with an r2 of 0.961 and MSEP of 0.006. The developed models can be used for developing insect pest control methods such as fuzzy temperature control and pesticide application scheduling.Biological model, insect population, insect flight, integrated pest management, yellow sticky paper
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(Downloads: 14)
Abstract (Viewed: 2)Tapioca starch-based film exhibits poor mechanical properties, thus limiting the application of the film as food packaging material. The present study aims to improve the mechanical properties of tapioca starch-based film by varying the concentration of glycerol (0, 5, 10, 15, 20, 25% w/w). Then, the starch-based films were incorporated with bulk chitosan (CH) and chitosan nanoparticle (CNP) to produce the starch/CH film and starch/CNP film, respectively. The mechanical properties of all the films which are tensile strength (TS), elongation at break (EAB), and Young's modulus (YM) were characterised using texture analyser. The morphological properties of both CH and CNP were observed under scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results revealed that 25% w/w of glycerol was sufficient to overcome the brittleness of film and improve the flexibility of the film. The addition of CH and CNP led to the increment in TS and EAB values of the films, thus confirming the role of the reinforcing agent of both CH and CNP in the films. A comparison study between CH and CNP demonstrated that CNP was more effective to improve the mechanical properties of the starch films compared to CH.Bulk chitosan, chitosan nanoparticles, food packaging, glycerol, ionic gelation, mechanical properties, tapioca starch.
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(Downloads: 8)
Abstract (Viewed: 2)This study focused on the optimization of hydrothermal conditioning conditions for Napier PakChong1 grass to produce press fluid for biogas production. The integrated generation of solid fuel and biogas from biomass (IFBB) process was adopted to separate press fluid from the biomass. Napier PakChong1 grass was hydrothermally pretreated and then mechanically pressed. The press fluid was used for biochemical methane potential (BMP) test while the press cake could be utilized as the solid fuel. The full factorial design of experiment with center points and the Central Composite Design (CCD) were developed to obtain the best possible combination of harvesting time, grass to water ratio, temperature and soaking time for the maximum organic substance (as COD) in press fluid. It was found that the obtained model could satisfactorily predict the mass of COD in press fluid used as the model response. The optimum hydrothermal conditioning conditions were as follows; harvesting time 75 d, ratio of grass to water of 1:6 (by weight), ambient temperature (about 25°C) of the water and the soaking time of 355 min. The mass of COD obtained in these conditions was 226.42 g equating to 71.5% of the value predicted by the model (316.68 g). The microbial kinetic coefficients and biogas yield potential of press fluid at these optimum conditions were properly fitted with the modified Gompertz equation (adjusted R2= 0.995). The methane yield potential (P), the maximum methane production rate (Rm) and lag phase time (λ) were 412.18 mlCH4/gVSadded, 51.47 mlCH4/gVSadded/d and 4.36 days, respectively.BMP, Grass liquor, hydrothermal conditioning, modified gompertz equation, pennisetum purpureum x pennisetum americanum (napier PakChong1 grass)
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(Downloads: 13)
Abstract (Viewed: 3)Oil palm is one of the major crops in Malaysia; it accounts for 47% of the global palm oil supply. Equatorial climate has provided Malaysia with the potential to produce oil palm biomass, which is one of the major contributors to the local economy. The utilisation of oil palm biomass as a source of renewable energy is one of the effective methods to promote green energy. Therefore, there is a need to have sufficient data related to oil palm biomass such as yield estimation, oil palm distributions, and locations. The aim of this study was to produce a land cover map on the distribution of oil palm plantations on three districts located in Selangor. Landsat 8 images of resolutions 15 x 15 m were used and classified via machine learning and non-machine learning algorithms. In this study, three different classifier algorithms were compared using support vector machines, artificial neural networks, and maximum likelihood classifications in which the values obtained for overall accuracy were 98.96%, 99.39%, and 15.30% respectively. The output showed that machine learning algorithms, support vector machines and artificial neural networks gave rise to high accuracies. Hence, the mapping of oil palm distributions via machine learning algorithm was better than that via non-machine learning algorithm.Landsat 8, machine learning, oil palm, remote sensing, support vector machine
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(Downloads: 9)
Abstract (Viewed: 1)This work describes the modification of quality index method (QIM) scheme for de-skinned Nile tilapia (Oreochromis niloticus) fillets, firstly developed for the farmed product in Iceland, and its application in sensory evaluation of the product originated from Vietnam during low temperature storage. Three batches of tilapia fillets were used during modification of the QIM scheme. During the storage study, five stable storage temperature regimes were set at 1, 4, 9, 15 and 19 ± 1°C, three batches of fish were assessed for every temperature. The modified QIM schemed consisted of 6 attributes, including Colour and Mucus of the skin side, Odour, Colour, Texture and Stickiness of the flesh (fillet side), with the total score or quality index (QI) of 13. Changes of some attributes and describing words from the previous scheme were made, due to the fish origin differences, to describe the sensory changes better. All the QI at different temperatures were in a well positive linear correlation with storage time. Furthermore, QI increased faster at higher storage temperatures. Parallel sensory evaluation by other methods like quantitative descriptive analysis (QDA) and Torry gave less clear sample differentiation throughout storage hours compared to QIM results. These supported the advantage of QIM over other methods and the application of QIM during cold chain management.Chilled product, tilapia, quality index method, sensory
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(Downloads: 11)
Abstract (Viewed: 2)This paper describes the properties determined to acquire physical and mechanical properties of unripe Nipah banana. In Malaysia, most of the banana chips processing companies use a variety from Nipah Banana,also known as Musa acuminata balbisiana a triploid hybrid banana cultivar. The physical (diameter, weight and peel thickness on edge and side) and mechanical properties (penetration and compression test) of Nipah Banana variety were determined through five consecutive days to evaluate its behaviour throughout its ripening period. The average diameter is 38.78±5.77 mm x 29.25±4.92 mm. The average thickness of peel at the edge and side are 5.3±0.93 mm and 3.65±1.01 mm respectively. The average weight of the Nipah banana variety is 77.85±28.61 g. Penetration force through 5 ripening days was found to decrease from 7.53N to 6.59 N (top position), 7.59N to 6.40N (middle position) and 8.31N to 6.43N (bottom position). The compressive force decreases through 3 days from 1704 N to 1630 N with the sudden increase in day 4 to 1380 Using the following properties accumulated, the machine components specification can be obtained which are the blade force required to slit the banana peel, the thickness of the blade needed for the slitting of banana peel, the roller force to hold the banana in place and the peeler size.Banana, mechanical properties, peeling machine, physical properties
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(Downloads: 16)
Abstract (Viewed: 1)The objective of this research was to evaluate the performance of a medium concentration-ozone treatment in maintaining the quality of freshness of ''Daw'' longan packed in different types of packaging materials. For fumigation with ozone gas, a batch size of 3 kg of longan fruit was fumigated for 5 minutes at a concentration of 4,000 ppm. The longan was then packed in three different types of packaging- polyethylene (PE), polypropylene (PP) and wrap film (WF), and was then stored at 5C for a shelf life of up to 36 days. Non-ozonated longan was kept as a control. The results showed that as storage time lengthened, the longan became more susceptible to disease incidences, pericarp browning, and weight loss under all treatments. During storage, the longan slightly changed in its firmness although there was no significant difference (p≥0.05) among the three different types of packaging. The ozonated longan stored in PE, PP, WF, and those with no-packaging had more L* and b* values and a longer shelf life, than those of the control. Among the three different types of packaging, the ozone fumigated longan stored in PE yielded the longest storage time with a shelf life of up to 36 days; an extended 140% longer shelf life as compared to the control.Fresh quality, longan, packaging materials, ozone fumigation, shelf life extension
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(Downloads: 10)
Abstract (Viewed: 1)Dried chili is normally contaminated with pesticide residue as a result from the excessive uses of pesticide in the field. The objective of this study was to determine the degradation kinetics of diazinon and triazophos pesticides in dried chili due to the oxidative potential of gaseous ozone fumigation. Both pesticides were spray-coated on dried chili and later fumigated with gaseous ozone at concentration rate of 5.5 g/hr for 30 min. Results showed that the degradation kinetic of diazinon and triazophos pesticides were presented on the first-order kinetic reaction. After 30 min of ozone fumigation, diazinon and triazophos residues were decreased by 69% and 47% with the half-life (t1/2) of 17.9 and 32.1 min, respectively. Scanning electron microscopy (SEM) images indicated that ozonated chili exhibited more rough surface morphology than unozoned chili. Ozone fumigation can be further developed as pesticide scrubber on agri-foods due to it high efficiency in term of shortening of half-life period and rapid pesticide decay rate.Degradation kinetics, diazinon, dried chili, half-life period, ozone, triazophos
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(Downloads: 11)
Abstract (Viewed: 3)The Sumani River is an important water resource used for agriculture and domestic purposes. The river is also the main water supply for Lake Singkarak and used for a power plant. Proper water resource management is required for sustainable water availability for all water users. A hydrological model is a necessary tool to assess water management in the watershed. However, most models require several data sources not readily available in developing countries that describe the internal structure of the watershed. Artificial neural networks (ANN) are biologically inspired computer programs designed to simulate the way in which the human brain processes information and are capable of modeling a nonlinear system. River flow is an indicator of water availability in the watershed. It is greatly influenced by rain, so it has a pattern for its intensity. The objective of this study was to develop an artificial network model to predict river discharge in the Sumani River from rainfall and discharge patterns. Multiple Layer Perceptron with the backpropagation algorithm was applied to predict river flow. Data on rainfall and discharge from the preceding day from 2008 to 2012 were used to train the model, and data from 2013 to 2014 were used to test the model. The Sumani River ANN scheme can be used to predict river flow with correlation coefficients of 0.95 and 0.92 in the training and testing stages.Artificial neural networks, Indonesia, river flow
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(Downloads: 9)
Abstract (Viewed: 2)The potential of fluorescence technology for monitoring Miyauchi Iyokan citrus during post-harvest treatment was investigated in this research. Citrus fruits were harvested when still a greenish-yellow color with a low soluble solids (SS)/acid ratio. Dark storage of fruits at 80-90% of RH and 6-10°C for sixty days is expected to increase the quality of the fruits (becoming reddish orange in color and having a high SS/acid ratio). However, monitoring the quality during the treatment is substantial. In general, farmers monitored the quality by seeing the appearance, however, this way is subjective. Thus, the fluorescence technique was proposed since it was objective, relatively cheap and easy to apply. Two main fluorescence compounds from peel, polymethoxylated flavones (PMFs) (Ex. 370 nm/Em. 540 nm) and tryptophan-like (Ex. 260 nm/Em. 330 nm) compounds were found, and PMFs were used in this research since it is an essential constituent for the fruit quality. This work demonstrated that during treatment bright yellow color (suspected PMF compounds) had appeared when excited under 365 nm with UV-light from the beginning of storage period until day eighty, however, day fifty and sixty showed stronger intensity. Furthermore, SS/acid ratio reached the highest peak in day sixty. In addition, on day sixty an unpleasant odor appeared, which might be related to the off-flavor condition of metabolic excess. These results demonstrate the potential of fluorescence to monitor citrus fruit quality changes during postharvest treatment.Acidity, iyokan, post-harvest treatment, polymethoxylated flavones, soluble solid content, tryptophan-like
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(Downloads: 14)
Abstract (Viewed: 3)The oil palm trunk (OPT) currently represents a massive volume of agricultural waste with great potential to be rapidly developed in the wood composite industry. An improvement in sawing technology has potential to improve the yield of the commercially hard outer core of the OPT by about 27 % thus replacing the present sub-optimal square sawing pattern with a more efficient and higher-yielding polygon sawing pattern. To achieve this, a 'wedge' device was designed to be mounted on the existing sawing carriage. The proper methodology was followed including extraction of the design layout of the machine, development of the schematic drawing and wireframe model, modification of the design in computer-aided design (CAD) environment, the performance of stress, total deformation, and fatigue analysis, and production of a complete drawing for fabrication purpose. Results from the analysis showed that the designed part was safe to be fabricated with a small maximum equivalent stress of 2.546 MPa, maximum total deformation of 0.007935 mm and total life cycle of one million cycles. These evaluation results indicate that the material used for the wedge device (including the base part) satisfies the design requirements of static strength and is safe within its designed fatigue life.Deformation, fatigue analysis, oil palm stems, polygon sawing pattern, sawmill carriage, stress, wedge
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(Downloads: 11)
Abstract (Viewed: 3)This study provides predictable flow behavior of a hybrid biocomposites made from kenaf/coir reinforced unsaturated polyester using the Moldflow software. A medium size electrical part has been chosen as a mold having multi-wall thicknesses and complex surfaces. Three different shapes of charges of the bulk molding materials were used and compressed into the mold part. The shapes of charges would be rectangular, cubic and cylindrical shapes. The results showed that rectangular charge took 0.2 seconds to fill up the part while the cubic and the cylindrical charges took 1.911 and 2.898 seconds respectively. After 70 seconds the conversion at nodes was more than 98% for all charges. On the other hand, the final densities were 1.88 ± 0.08 g/cm3 for all charges. The cubic charges showed a better temperatures distribution at flow front followed by rectangular, the last being the cylindrical charge, and the average shrinkage was 5-7% for the charges. The cubic shape showed good fibers orientation to the flow direction of the bulk materials followed by cylindrical charge while the rectangular charge showed poor orientation of fibers affected on the deflections, weld lines and air traps in the internal part. For the rectangular, the charge showed more critical weld lines and more air traps especially on the surface of the molded part and more deflections on the corner edges. But, the cubic charge showed the lowest deflections rate, air traps and weld lines defects.Coir, compression molding, hybrid biocomposites, kenaf, moldflow simulation
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(Downloads: 15)
Abstract (Viewed: 2)Basal stem rot (BSR) caused by Ganoderma boninense is a major disease attacking the oil palm plantation in Malaysia, and incur big losses in palm oil industries. The disease is spread mostly by root either through spore availability in soil or roots contacts. Soil properties were reported to have significant influence on the growth of fungi. Meanwhile, the value of soil resistivity is influenced by soil properties. This paper presents a new approach of BSR detection by using soil moisture sensor which measures resistivity of soil in unit ohm (Ω) at 15 cm surrounding the basal stem of oil palm trees. The study was conducted on 39 oil palm trees at different healthiness levels. The sensor was embedded approximately 4.7 cm deep in the soil at eight different points for each palm. The results showed that healthy oil palm trees significantly have higher mean (ERMEAN ≥ 400) of electrical resistance (ER) readings compared to infected trees (ERMEAN< 400). More specifically, ER readings at points without symptoms (i.e. fruiting bodies and/or hollow) were significantly higher compared with ER readings at points where symptoms appeared even though the points of measurements were on the same palm. This finding has brought to the introduction of a new index to detect Ganoderma infection, named as K-index. Combination of ERMEAN taken from eight points of measurement and its K-index gave better results of detection and a new model was developed based on these two parameters (i.e. ERMEAN and K-index). The developed model has accuracy rates of 82% and gained 100% successful rate during validation. This research showed that soil resistivity can contribute to Ganoderma-infected detection in oil palms with a high degree of accuracy.Basal stem rot, electrical resistance, ganoderma boninense, soil moisture sensor, soil resistivity

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