Paddy Grain Research Articles

Comparative examination of leaching kinetics of soluble solids and effluent characteristics in different soaking processes of paddy parboiling

ABSTRACT Paddy was soaked with up to 30% moisture, and hot water soaking (35, 40, 45, 50, 55, 60 °C) was compared to cold soaking (CS) and submerged aerated soaking (SAS) in terms of the parameters of the paddy grain and the effluent. The investigation demonstrated that hot water soaking yielded the highest total solids (TS) (1.946 ± 0.045 g/L), total dissolved solids (TDS) (1.724 ± 0.013 g/L), and electrical conductivity (EC) (2.651 ± 0.039 mS/cm) values. Elevated dissolved oxygen (DO) (3.72 ± 0.04 mg/L) was observed in the hot water soaking (60 °C) due to the reduction of soaking duration of up to 2 h. By contrast, the SAS maintained a nearly neutral pH (7.35 ± 0.01) and lower turbidity (510.0 ± 1.4 NTU) level compared to the hot water soaking process. The leaching rates and moisture absorption were computed using pseudo-second-order leaching kinetics and Peleg model absorption kinetics, and a higher leaching rate (0.081 g/L min) was detected at 60 °C. The SAS produced higher efficiency with less resource consumption and an environmentally advantageous approach by reducing effluent strength and maintaining total solids in paddy grains. The new knowledge created by the comprehensive evaluation CS, SAS, and hot water soaking of paddy parboiling using leaching models and paddy hydration adds new insights to the development of efficient paddy parboiling methods.

Techno-economic Analysis Conversion of Empty and Partially Filled Paddy Grain Waste into Glucose through Bioconversion Route

Waste generated from Malaysia’s paddy milling factories, known as empty and partially filled paddy grain (EPFG), has been improperly managed as it can be further utilized for sustainable resources such as feedstock via biorefinery. However, the critical driver for a biorefinery is whether the proposed design is profitable. In this study, the conversion of EPFG into glucose as an alternative to sustainable management was analysed in terms of their economic performance as feedstock. The process design involved the production of non-concentrated glucose from EPFG using hydrothermal pre-treatment and enzymatic process, which led to the 76% conversion yield. The economic performance for the plant is at 1.04 million USD, 46.9%, and 34.3% for net present value (NPV), return on investment (ROI), and internal rate return (IRR), respectively. The minimum sugar selling price (MSSP), when zero NPV, is at 0.42 $/kg when the co-product revenue is considered. Sensitivity analysis results indicate that the MSSP is highly sensitive to plant size. This economic evaluation serves as an introductory guide to assess the economic performance of paddy milling waste to glucose via enzymatic hydrolysis. The results of the present study could provide insight for the Malaysian paddy industry in managing the EPFG, hence increasing their market potential.

Electrochemical evaluation of fenitrothion organophosphate pesticide in food samples: Novel tetra trifluoromethyl carboxamide zinc (II) macrocyclic complex composite with multiwalled carbon nanotubes

This study presents the development of a groundbreaking electrochemical sensor for detecting fenitrothion (FNT) using a multi-walled carbon nanotubes (MWCNTs) and a newly synthesized zinc (II) tetra trifluoromethyl carboxamide phthalocyanine (ZnTFMPCAPc). The ZnTFMPCAPc was synthesized concluding a two-step mechanical and magnetic stirring method, and the ensuing ZnTFMPCAPc@MWCNTs underwent comprehensive characterization employing X-ray diffraction (XRD), Ultraviolet visible spectroscopy (UV–Vis), mass spectrum, Fourier transform infrared spectroscopy (FT-IR), Thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Mass, Raman spectra, Transmission Electron Microscopy (TEM) and scanning electron microscope (SEM). Cyclic voltammetry (CV) analysis demonstrated a remarkable seven-fold improvement in electrochemical signals with ZnTFMPCAPc@MWCNTs on modified glassy carbon electrode (GCE) compared to a bare and modified GCE. The correlation between peak current and FNT concentration (in the range of 10–310 μmol) was established. The estimated limits of detection (LOD) and quantification (LOQ) were determined to be 1.358 nmol and 4.075 nmol respectively. The ZnTFMPCAPc@MWCNTs/GCE sensor was successfully evaluated by quantifying FNT in tomatoes, grapes, paddy grains, and potato extracts, resulting in satisfactory results. Detecting fenitrothion is crucial due to its widespread use as a pesticide, which can result in environmental contamination and pose health risks. Regular monitoring is essential for protecting food and water supplies, preserving ecosystems, and ensuring compliance with regulations to prevent long-term environmental damage.

Evaluation of airflow, temperature, and RH in the deep bed dryer for paddy grain with several combinations of floors and air distribution pipes using CFD

Evaluation of airflow, temperature, and RH in the deep bed dryer for paddy grain with several combinations of floors and air distribution pipes using CFD

Mechanized wet direct seeding for increased rice production efficiency and reduced carbon footprint

Crop establishment is one of the major rice production operations that strongly affects rice production, productivity, and environmental impacts. This research introduced a new technology and provided scientific evidence for the benefits of mechanized wet direct seeding (mDSR) of rice as compared with the other crop establishment practices commonly applied by farmers for wet direct seeded rice in Mekong River Delta in Vietnam, such as seeding in line using drum-seeder (dDSR) and broadcast seeding (bDSR). The experiment was implemented across two consecutive rice cropping seasons that are Winter-Spring season and Summer-Autumn season in 2020–2021. Treatments included (1–3) mDSR with seeding rates of 30, 50, and 70 kg ha− 1, (4) dDSR with 80 kg ha− 1 seed rate, and (5) bDSR as current farmer practice with seeding rate of 180 kg ha− 1. The fertilizer application was adjusted as per seeding rate with 80:40:30 kg ha− 1 N: P2O5: K2O with lower seed rate 30 and 50 kg ha− 1 in mDSR; 90:40:30 kg ha− 1 N: P2O5: K2O with medium seed rate of 70 to 80 kg ha− 1; and 115:55:40 kg ha− 1 N: P2O5: K2O with high seed rate of 180 kg ha− 1 in bDSR. Mechanized wet direct seeding rice with a lower seed rate of 30 to 70 kg ha− 1 and fertilizer rate by 22–30% reduced variation in seedling density by 40–80% and in yield by 0.1 to 0.3 t ha− 1 and had similar yield to bDSR. In consequence, N productivity was 27 and 32% higher in mDSR as compared to bDSR during the Winter-Spring season and Summer-Autumn seasons, respectively. The use of lower seed rate and fertilizer in mDSR also led to higher income and lower carbon footprint (GHGe per kg of paddy grains) of rice production than the currently used practices of bDSR. Net income of mDSR was comparable to that of dDSR and higher by 145–220 and 171–248 $US than that of bDSR in Winter-Spring season and Summer-Autumn, respectively. The carbon footprint of mDSR rice production compared to bDSR was lower by 22–25% and 12–20% during the Winter-Spring and Summer-Autumn seasons, respectively. Given the above benefits of farming efficiency, higher income, and low emission, mDSR would be a technology package that strongly supports sustainable rice cultivation transformation for the Mekong River Delta of Vietnam.

Biofortifying drought-tolerant rice: enhancing growth and nutritional quality with foliar iron and zinc applications in Eastern India

Micronutrient deficiencies in staple food crops pose a significant global health concern, especially in regions prone to drought. Agronomic biofortification offers a promising solution by enhancing the content of essential micronutrients. This study aims to identify efficient rice varieties for iron (Fe) and zinc (Zn) biofortification through foliar applications. A field experiment was carried out during kharif season in 2019 and 2020 with four drought-tolerant rice varieties (Swarna Shreya, Swarna Shakti Dhan, Sahbhagi Dhan, and DRR Dhan 42) were assessed under four foliar applications of Fe and Zn (control, 1% of Fe, 1% of Zn and combined 1% of Fe + 1% of Zn) at Indian Council of Agricultural Research-Research Complex for Eastern Region (ICAR-RCER), Patna. The highest grain yield of 5.65 t/ha was attained with the main plot treatment, Swarna Shreya variety, and in the subplot treatment, Fe + Zn foliar application resulted in a yield of 5.50 t/ha. The combined foliar application of Fe + Zn demonstrates the highest chlorophyll content and starch synthesis. Foliar application of combined Fe and Zn increased paddy grain Fe and Zn concentration by up to 30 and 16%, respectively, compared to the control. This finding is important for addressing micronutrient deficiencies in regions where rice is a dietary staple. Thus, Swarna Shreya, in combination with iron and zinc foliar application is a promising option for enhancing yield and fortifying grains in rainfed areas of eastern India.

Efficient Paddy Grain Quality Assessment Approach Utilizing Affordable Sensors

Efficient Paddy Grain Quality Assessment Approach Utilizing Affordable Sensors

Identification of Paddy Stages from Images using Deep Learning

Rice, a crucial global staple, is integral to food security. Precise identification of paddy growth stages, booting, heading, anthesis, grain filling, and grain maturity is vital for agricultural decisions. However, a gap exists in recognizing these stages using red-green-blue (RGB) images. This study uses state-of-the-art computer vision and deep learning classification (Convolutional Neural Networks) algorithms to address this gap. Among the studied algorithms, EfficientNet_B0 achieved an impressive 82.8% overall accuracy. Notably, increasing image size from 64X64 pixels to 128X128 pixels significantly enhanced accuracy. A detailed assessment of growth stages revealed varying accuracy levels, with boot leaf being the most accurately detected (95.1%) and anthesis being the most challenging (72.28%). This work significantly advances automated monitoring, empowering researchers in real-time decision-making.

Illuminating the path to sustainable rice harvesting: A solar-based paddy harvester

Paddy is the most important agricultural crop product in Bangladesh since it is widely used in daily life as a main meal intake. Currently, traditional manual harvesting process is widely used to harvest paddy grains in Bangladesh. However, manual harvesting is laborious, time-consuming, and costly. Utilization of modern machineries such as combined paddy harvester machines can increase grain productivity while reducing significantly the number of labour-hours. Combine rice harvesters possess traditional diesel engine that burns gasoline fuels i.e. diesel. The overriding concern of this diesel oil combustion is the production of greenhouse gases that adversely affect the environment. In addition, reports suggest that oil reserve might be depleted to zero in next 40 years. This manuscript presents a comprehensive review on the paddy grain production statistics, the pros and cons of traditional rice crop harvesting processes, and the historical development of mechanization in the agricultural sectors of Bangladesh. It also presents a novel design route to convert commercial diesel-driven combine paddy harvester machine to solar energy-operated combine rice harvester machine with its required accessories. In particular, a new design concept with a remarkable cost estimation process of solar-powered harvesters is proposed. A field study has been conducted in Sonagazi Upazilla under Feni district of Bangladesh to evaluate the potential use of the proposed solar-powered harvester machine. Our study suggests that solar-driven rice harvester is a promising concept in the paddy crop harvesting process and it will reduce the overall costs for short and long-term uses compared to estimated costs of commercial diesel-driven harvesters. To combat the scarcity of gasoline in the future, it is an obvious choice to bring a paradigm shift in solar energy harvesting and its utilization in the agricultural sectors of Bangladesh. It is expected that the proposed solar-driven rice harvester concepts with their in-depth analysis (including costs) would be able to draw attention to business entrepreneurs and investors who will be excited to initiate a program to manufacture solar-powered rice harvester machines in practice.

Effect of different storage conditions on grain quality of paddy

The present investigation was carried out to study the physiological and biochemical changes of paddy grain (Oryza sativa L. var. Ranjit) throughout the course of a 12-month storage period, in an effort to determine the ideal storage conditions with the highest potential for storage under climacteric condition of Assam. Freshly harvested seeds of paddy grain (Ranjit) were stored under different storage conditions for a period of twelve months beginning in January. Based on the results of the study, it was found that the easily moisture permeable structures (T2, T3, T6) showed the maximum change in the physiological and biochemical parameters followed by permeable (T1 and T4) and impermeable (T5 and T7). The rate of change in the values of parameters in paddy stored in the prototype of a Grain safe™ in-store dryer (T7) was found slowest and sluggish, and maintained highest mean values amongst all the storage receptacles in respect of germination percentage, seed vigour index, head rice recovery, moisture content, total soluble protein content, starch content, total soluble sugar content, reducing sugar, non-reducing sugar and amylose content. Significant superiority of hermetic storages (T5 and T7) over traditional storage structures (T1, T2, T3, T4 and T6) in Assam irrespective of all the parameters studied was noticed. Hermetic storage was effective at blocking the effects of external humidity fluctuations as well as the spread of fungi and insects. The solar in-store drier was found to be best amongst all storage structures, in all quality aspects of the long-term storage of paddy.

Effects of Bipolaris yamadae strain HXDC-1-2 as a bioherbicide against Echinochloa crus-galli in rice and dry fields.

Barnyardgrass (Weed Science Society of America recommended) or Barnyard grass (Britannica recommended) (Echinochloa crus-galli (L.) P. Beauv.) is one of the most problematic and dominant weeds in world agricultural systems, especially in paddy fields, where tillering and grain yield can be reduced by 50-70% because of its competitive pressure. The frequent use of chemical herbicides to control E. crus-galli has led to the evolution of herbicide resistance. Developing bioherbicides using pathogenic fungi to control E. crus-galli could be an alternative option. In a previous study we showed that a strain of Bipolaris yamadae (HXDC-1-2) was promising in controlling gramineous weeds. Here we present a study that evaluated this fungus as a mycoherbicide against E. crus-galli in greenhouse and paddy fields, characterized mycelium growth and conidial production, and examined the infection development. The median effective dose (ED50) and 90% effective dose (ED90) values of microcapsulated B. yamadae strain HXDC-1-2 on E. crus-galli in the greenhouse were 7.17 × 102 and 9.35 × 103 conidia mL-1, respectively. Conidial germination, mycelial growth, and attachment formation occurred on E. crus-galli leaves within 1 to 6 h. The hyphae directly invaded cells and stomata, primarily from the appressorium on the epidermis, and necrotic lesions were observed on the leaf surface within 20 to 24 h. Applied to E. crus-galli plants at 1 × 105 conidia mL-1, the fungus reduced the weed's fresh weight of 75%. B. yamadae strain HXDC-1-2 has the potential to be developed as a bioherbicide against E. crus-galli plants, especially in rice fields. © 2024 Society of Chemical Industry.

MEASUREMENT OF RICE MOISTURE CONTENT BASED ON QUANTITATIVE ANALYSIS FROM RADIO TOMOGRAPHY IMAGES

Inefficient storage of paddy and rice grains can lead to grain deterioration, resulting in post-harvest losses ranging from 10% to 30%. The quality of grains cannot be improved throughout the storage period. Therefore, following the mechanisation of agricultural industries, air dryers have been developed to control the crops’ moisture level by blowing ambient or heated air into the silo to improve the aeration and allow the grains to be preserved with minimal loss of quality until the appropriate time for managing and marketing processes. However, the conventional sampling method used to measure the moisture level is inefficient because it is very localised and only represents part of the moisture distribution inside the bulk grains. Additionally, incorporating advanced technologies can be a significant cost limitation for small-scale industries. Thus, to address the issue, this research study developed a radio tomographic imaging (RTI) system in a silo-scale prototype using 20 sensor nodes operating at 2.4 GHz to localise and monitor the moisture level constructively. The RTI system reconstructs the cross-sectional images across the rice silo by measuring radio frequency attenuation, in terms of received signal strength (RSS) quality, caused by the rice moisture phantoms within the wireless sensor network (WSN) area. A total of five phantoms’ profiles having a percentage of moisture content (MC) of 15%, 20% and 25% were reconstructed using four image reconstruction algorithms, Linear Back Projection (LBP), Filtered Back Projection (FBP), Newton’s One-step Error Reconstruction (NOSER) and Tikhonov Regularisation.

Evaluation of the efficacy of cinnamon oil on Aspergillus flavus and Fusarium proliferatum growth and mycotoxin production on paddy and polished rice: Towards a mitigation strategy

In the present investigation, the effect of cinnamon oil (CO) (10, 30, 50 and 70 %) on the growth rate (mm/day) and aflatoxin B1 (AFB1) and fumonisin B1 (FB1) production of Aspergillus flavus (AF01) and Fusarium proliferatum (FP01) isolates, respectively was determined at optimum water activities (0.95 and 0.99 aw) and temperatures (25, 30 and 35 °C) on paddy and polished rice grains. The results showed that the growth rate, AFB1 and FB1 production of all the fungal isolates decreased with an increase in CO concentrations on both matrices. AF01 and FP01 failed to grow under all conditions on paddy at 50 % of CO concentration whereas both fungi were completely inhibited (No Growth-NG) at 70 % of CO on polished rice. Regarding mycotoxin production, 30 % of CO concentrations could inhibit AFB1 and FB1 production in both matrices (No Detection-ND). In this study, the production of mycotoxins was significantly influenced by cinnamon oil compared to the growth of both fungi. These results indicated the promising potential of CO in improving the quality of rice preservation in post-harvest; however, further investigations should be evaluated on the effects on the qualitative characteristics of grains. Especially, the prospective application of CO in rice storage in industry scales to mitigate mycotoxin contamination need also to be further researched. Moreover, collaboration between researchers, agricultural experts, and food industry should be set up to achieve effective and sustainable strategies for preserving rice.

Foliar spraying of Zn/Si affects Cd accumulation in paddy grains by regulating the remobilization and transport of Cd in vegetative organs

The reduction of cadmium (Cd) accumulation in rice grains through biofortification of essential nutrients like zinc (Zn) and silicon (Si) is an area of study that has gained significant attention. However, there is limited understanding of the mechanism of Zn/Si interaction on Cd accumulation and remobilization in rice plants. This work used a pot experiment to examine the effects of Zn and Si applied singly or in combination on the physiological metabolism of Cd in different rice organs under Cd stress. The results revealed that: Zn/Si application led to a significant decrease in root Cd concentration and reduce the value of Tf Soil-Root in filling stage. The content of phytochelatin (PCs, particularly PC2) and glutathione (GSH) in roots, top and basal nodes were increased with Zn/Si treatment application. Furthermore, Zn/Si treatment promoted the distribution of Cd in cell wall during Cd stress. These findings suggest that Zn/Si application facilitates the compartmentalization of Cd within subcellular structures and enhances PCs production in vegetative organs, thereby reducing Cd remobilization. Zn/Si treatment upregulated the metabolism of amino acid components involved in osmotic regulation, secondary metabolite synthesis, and plant chelating peptide synthesis in vegetative organs. Additionally, it significantly decreased the accumulation of Cd in globulin, albumin, and glutelin, resulting in an average reduction of 50.87% in Cd concentration in milled rice. These results indicate that Zn/Si nutrition plays a crucial role in mitigating heavy metal stress and improving the nutritional quality of rice by regulating protein composition and coordinating amino acid metabolism balance.

Few-shot learning convolutional neural network for primitive indian paddy grain identification using 2D-DWT injection and grey wolf optimizer algorithm

Rice (Oryza sativa) is extensively taken and sold throughout the world. The most common primitive paddy are Goswami, Jamuna, Jamut, Mamata, Pooja, Rambanbas, Sanghmitra, Sanjeevani, Sadhana, and Sannasriya. The primary objective of this study is to enhance the classification accuracy of few-shot learning datasets via the development of a reliable feature extraction approach and the Optimization of convolutional neural network (CNN) hyperparameters. Here, the 2D-DWT features were injected before the fully connected layer and added to the deep features of the CNN. Furthermore, the hyperparameters of the CNN layer were optimized using the Grey Wolf Optimizer (GWO). This optimization strategy enhances the recognition rate on a limited training dataset, and the injection of 2D-DWT increases the dimension of the feature vector, which further elevates the performance of the model. The performance of proposed model is examined with our own dataset, which is shared in mendely (sethy, PRABIRA (2023), “PRIMITIVE PADDY VARITIES OF ODISHA, INDIA”, Mendeley Data, V1, https://doi.org/10.17632/67zv95bzt8.1) and achieved accuracy of 98.50 %, sensitivity of 98.50 %, specificity of 99.83 %, precosion of 98.56 %, FPR of 0.17 %, F1score of 98.50 %, MCC of 98.35 % and kappa of 91.67 %.

Effects of selenium on biogeochemical cycles of cadmium in rice from flooded paddy soil systems in the alluvial Indus Valley of Pakistan

This study delves into the pollution status, assesses the effects of Se on Cd biogeochemical pathways, and explores their interactions in nutrient-rich paddy soil-rice ecosystems through 500 soil-rice samples in Pakistan. The results showed that 99.6 % and 12.8 % of soil samples exceeded the World Health Organization (WHO) allowable Se and Cd levels (7 and 0.35 mg/kg). In comparison, 23 % and 6 % of the grain samples exceeded WHO's allowable Se and Cd levels (0.3 and 0.2 mg/kg), respectively. Geographically Weighted Regression (GWR) model results further revealed spatial nonstationarity, confirming diverse associations between dependent variables (Se and Cd in rice grain) and independent variables from paddy soil and plant tissues (root and shoot), such as Soil Organic Matter (SOM), pH, Se, and Cd concentrations. High Se:Cd molar ratios (>1) and a negative correlation (r = −0.16, p < 0.01) between the Cd translocation factor (Cd in rice grain/Cd in root) and Se in roots suggest that increased root Se levels inhibit the transfer of Cd from roots to grains. The inverse correlation between Se and Cd in paddy grains was further characterized as Se deficiency, no risk, high Cd risk, Se risk, Cd risk, and Se–Cd co-exposure risk. There was no apparent risk for human co-consumption in 42.6 % of grain samples with moderate Se and low Cd. The remaining categories indicate differing degrees of risk. In the study area, 31 % and 20 % of grain samples with low Se and Cd indicate Se deficiency and risk, respectively. High Se and low Cd levels in rice samples suggest a potential hazard for severe Se exposure due to frequent rice consumption. This study not only systematically evaluates the pollution status of paddy-soil systems in Pakistan but also provides a reference to thoroughly contemplate the development of a scientific approach for evaluating human risks and the potential dangers associated with paddy soils and rice, specifically in regions characterized by low Se and low Cd concentrations, as well as those with moderate Se and high Cd concentrations. SynopsisThis study is significant for understanding the effects of Se on Cd geochemical cycles and their interactions in paddy soil systems in Pakistan.

State-of-the-art Overview of Biological Treatment of Polluted Water from Rice Mills and Imminent Technologies with Green Energy Retrieval

Rice milling involves shelling and polishing paddy grains to produce rice- both raw and parboiled. Parboiled rice production requires a massive quantity of freshwater for soaking, which, in turn, generates a large amount of wastewater. If this wastewater is not properly ameliorated, it can cause tremendous troubles of surface water pollution, land pollution, and, ultimately, groundwater pollution. Therefore, proper treatment of polluted water from rice mills (PWRM) as per the effluent discharge norms is necessary to protect the surface and subsurface water resources for sustainable development. There are two methods for remediating rice mill wastewater- physicochemical and biological. The biological methods produce comparatively less sludge and are cost-effective. Moreover, these processes are capable of retrieving green energy in the form of biomethane, biohydrogen, and bioelectricity to augment bio-fuel production, aiming to meet the ever-increasing fuel demands caused by rapid industrialization, motorization, and urbanization. The focus on green energy production is gaining momentum day by day due to the adverse effects of conventional energy derived from fossil fuel combustion in terms of enhanced Air Pollution Index (API) in the ambient atmosphere. In this paper, anaerobic biodegradation, phytoremediation, phyco-remediation, and microbial fuel cell techniques adopted by various researchers for remediating the polluted water from rice mills have been well addressed and critically discussed. The pros and cons of these biological methods have been well addressed to assess the socio-technoeconomic feasibility of each method.

Assessment of Heavy Metal Content and Consumption Risks At Selected Paddy Field in Malaysia: A Review

As the Malaysian population grows, there is a high demand for rice, the main staple food in this region. This has caused the overuse of agrochemicals that contain heavy metals and the utilization of contaminated groundwater to increase paddy yield, posing a risk to humans. This study reviewed the accumulated heavy metals in paddy fields of Malaysia's Selangor, Kedah and Sabah states and further calculated the consumption risks of rice grains from the selected areas. The study revealed that paddy soil in Ranau Valley (Sabah), Kota Marudu (Sabah) and Tanjung Karang (Selangor) showed presences of Cu and Cd in high concentration, respectively, creating higher potential to be uptake by paddy roots. These findings also revealed that Ranau Valley (Sabah) paddy grains contained high Cu and Cd concentrations, while Sabak Bernam (Selangor) contained high Pb concentrations. Further, a higher Cd concentration was reported from the Ranau Valley (Sabah), while the higher Pb concentrations were reported from the samples collected from Sabak Bernam (Selangor), Tanjung Karang (Selangor) and Kubang Pasu (Kedah). Based on the health risk indices calculation in this study, carcinogenic and non-carcinogenic health risks in all study areas except in Kubang Pasu (Kedah) and Langkawi (Kedah) are likely to occur due to Cu mining activities, ultrabasic soil contamination, utilization of contaminated groundwater and rock phosphate fertilizer and vehicular emission. Regular assessment of heavy metal content and consumption risks of paddy is essential to ensure the paddy field is free from contamination and will help protect the ecosystem and human health.

Characterization of secondary metabolites from the leaves of curry leaf (Murraya koenigii L.) essential oils with insecticidal activities against stored product insects

Curry leaf, a significant aromatic shrub belonging to the Rutaceae family, is indigenous to the Indian subcontinent and is widely renowned for its application as a flavor enhancer. Due to specific flavor and fragrance, the leaves of M. koenigii have been recognized for their potential contributions to human health. Curry leaf essential oils have recently received much attention due to their numerous benefits and minimal risk to non-target organisms. This work focused on the comprehensive characterization of secondary metabolites present in the essential oil extracted from curry leaves and aims to evaluate its insecticidal potential in terms of contact, fumigant, and repellent activities against red flour beetle (Tribolium castaneum) and pulse beetle (Callasobruchus maculatus) for first time. Chemical characterization through GC-MS/MS showed that the main chemical compounds within curry leaf essential oil were caryophyllene (28.47%), α-guaiene (13.35%), and α-phellandrene (12.26%). Notably, results from various insecticidal bioassays showed substantial effects upon contact (LC50 at 24 h, 10.56 mg/cm2 for T. castaneum, 20.80 mg/cm2 for C. maculatus) and fumigant toxicities (LC50 at 24 h, 23.93 mg/L air for T. castaneum, 12.96 mg/L air for C. chinensis), alongside repellent activities (at 5 mg/cm2, a mean PR of 90% to T. castaneum and at 5 mg/cm2, C. maculatus demonstrated 80% PR, targeting both insects. Furthermore, a phytotoxicity assessment was performed on stored paddy grains, and neither seedling development nor germination rates were negatively affected. The essential oils extracted from curry leaves exhibit considerable potential as botanical insecticides that are effective against stored-product insects and environmentally benign.

Multi-frequency microwave dielectric properties-based method coupled with SPA-PLSDA algorithm for rapid discrimination of grain mildew

To achieve in-situ monitoring of the occurrence of grain mildew and ensure food safety, this study took paddy grains as the object and carried out the discrimination of paddy mildew based on microwave dielectric properties. The multi-frequency swept measurement technique was used to acquire the dielectric constant (DC) and dielectric loss factor (DLF) spectra (2.00–10.00 GHz) of healthy samples and samples with different moldy paddy content. To choose the most effective frequencies, 20 frequency subsets (DC subset 1–10, DLF subset 1–10) were generated by an algorithm coupled with the successive projections algorithm and partial least-squares discriminant analysis. Afterward, four key frequencies were determined from the 100 pairwise combinations of the two types of frequency subsets by exhaustive method. Dielectric properties at key frequencies and sample thickness were used as the input variables to establish the discriminating model for paddy mildew. The established microwave dielectric properties-based model achieved 100% accuracy in distinguishing healthy and moldy samples, showing perfect discriminant validity. Moreover, only 4.4% of those samples whose MPC was at a low level (≤30%) were misclassified by the model, and the discrimination model achieved 97.29% overall accuracy. The results of this study should encourage future research on dielectric-based mildew detection in food processing and agriculture-related industries.