Air-drying Methods Research Articles

Drying kinetics and quality characteristics of exocarpium citreic grandis slices with hot air, vacuum, and microwave vacuum dryers

The study investigates the impact of different drying methods on the selection of thin-layer drying kinetic models, parameters, and quality for Exocarpium Citreic Grandis. This study investigates the drying characteristics, index constituents content, and microscopic structures of Exocarpium Citreic Grandis slices, subjected to three drying techniques: HAD (at 50, 60, 70∘C), VD (at 50, 60, 70∘C), and MVD (at 1000, 1500, 2000W). A thin-layer drying kinetic model was established. The findings demonstrated that the drying process was primarily dominated by the falling rate phase. When the drying temperature was 70∘C and the microwave power was 2000W, the HAD VD, and MVD took 120, 360, and 20 minutes respectively. By fitting six commonly used thin-layer drying models, it was discovered that the optimal mathematical models for HAD, VD, and MVD were the Page model, the Logarithmic model, and the Page model, respectively. The highest average R2 values were 0.9963, 0.9965, and 0.9964, and the lowest average RMSE values were 0.01782, 0.01704, and 0.0174 respectively. The effective diffusion coefficient increased with the drying temperature and microwave power, with MVD having the maximum coefficient. As the temperature and microwave power increased, the contents of naringin and rhoifolin decreased. However, the naringin content in MVD was 23.05% and 45.71% higher compared to hot air and VD respectively. The cross-section of Exocarpium Citreic Grandis dried via microwave vacuum exhibited a porous honeycomb structure with uniformly distributed spaces and larger pores, reflecting an expansion effect. The HAD process also resulted in a honeycomb-like structure, but with smaller pores. The VD process resulted in a layered structure with significant cell collapse. Microwave vacuum drying demonstrates superior energy efficiency and product quality compared to hot air and vacuum drying methods. The study finds that microwave drying does not have a destructive impact on the active compounds of Exocarpium Citreic Grandis. To facilitate large-scale, continuous production, microwave drying can be practically applied in industrial processing.

Drying of Highland Bamboo (Oldeania alpina) Culms Grown in Ethiopia as Quality Enhancement

Drying is an essential step in the manufacturing process of bamboo culms which enhances its quality. Even though in the case of Ethiopia, effective bamboo culm drying has not been practiced. This is due to limited information/technology regarding bamboo culm drying. Therefore, this study aimed to investigate the effective drying technologies and the effect of site and culm height on the drying characteristics of Oldeania alpina (O. alpina). For this study, matured 3-5 years old samples of O. alpina culms sectioned into three segments were collected from Hagere-Selam and Rebu-Gebeya, Ethiopia. The culms were stacked and dried using kiln and air-drying methods. The mean values of basic density in O. alpina collected from Hagere-Selam and Rebu-Gebeya sites were 0.65 and 0.63 gcm-3, respectively. The average initial moisture content (MC) of Hagere-Selam and Rebu-Gebeya culms were 91.78% and 80.32%, respectively. The Hagere-Selam culm kiln-dried within 6.5 days while air-dried within 75 days to attain the final MC for kiln (10.15%) and air-drying (14.13%). The Rebu-Gebeya culm kiln dried within 5.4 days while they required 61 days for air-drying to attain the final MC for the kiln (10.60%) and air-drying (13.01%). The MC and drying time needed for drying the culms were significantly affected by site, culm height, and drying method. Drying O. alpina culms using kiln and air-drying methods was successful without significant drying defects. Well-seasoned culms of Hagere-Selam and Rebu-Gebeya are recommended for wider utilization in Ethiopia including furniture, flooring, handcrafts, etc.

Assessment of Total Phenolic Compounds, Antioxidant Capacity, β-Carotene Bioaccessibility, HMF Formation, and Color Degradation Kinetics in Pumpkin Pestils

Pestil, often known as fruit leather, is one of the most significant traditional foods manufactured and consumed throughout Türkiye. Due to its practical consumption, the availability of numerous nutrients, and the ability to meet energy requirements, pestil is recognized as a snack food. The aim of this study was to evaluate the bioaccessibility of total phenolic compounds (TPC), antioxidant capacity (AOC), and β-carotene in pumpkin pestils dried by hot air drying (HAD), vacuum drying (VCD), and microwave drying (MD) methods using an in vitro digestion model. Additionally, 5-hydroxymethylfurfural (HMF) formation and color degradation of pestils were evaluated. Changes in TPC and AOC were determined using spectrophotometric methods, whereas the detections of β-carotene and HMF were carried out with high performance liquid chromatography–photodiode array detector (HPLC–PDA). Significantly higher TPC (10.99–105.70%) and AOC (15.30–118.58%, 21.88–401.04% and 89.28–482.14%, in CUPRAC, FRAP, and DPPH assays, respectively) values were observed after drying (p<0.05). Moreover, it was observed that there were statistically significant increases in TPC and AOC values after digestion for all pumpkin pestils compared to undigested samples (p<0.05). Drying process resulted in lower β-carotene content (between 32.15–61.11%) in pumpkin pestils; however, it increased the percentage of bioaccessible β-carotene (max 62.16%) in the pestil samples. Compared to HD and VCD techniques, pumpkin pestils dried with MD exhibited significantly higher TPC, AOC and β-carotene content (p<0.05). All of the pumpkin pestils except those dried by MD at 180 W contain HMF below the Turkish Standards Institute legal limit of 50 mg/kg. L* value of pestils were described adequately to the zero- and first-order kinetic models while a* and b* values were only fitted to zero-order model. In conclusion, the findings obtained in this study pointed out that drying processes (especially by MD method) increased the bioaccessibility of TPC, AOC, and β-carotene.

β-Carotene and Lycopene Degradation Kinetics of Tarhana Dough During Convective Air Drying and Traditional Drying Methods

In this study, tarhana doughs were dried with convective air drying at 30, 40 and 50 oC temperatures and 0.5, 1.25 and 2 m/s air velocities, and with traditional drying (sun-drying method). By this way effects of drying air temperature and velocity on degradation kinetics of β-carotene and lycopene during air drying of tarhana samples were investigated and the results compared with traditional drying method. The degradation reaction of β-carotene and lycopene was found to be following the first-order kinetic model. The reaction rate constant values of the β-carotene degradation were determined in the range of 0.0003-0.0025 min-1, and the activation energy values were determined in the range of 6.15-49.05 kJ/mol. The reaction rate constant values of the lycopene degradation were determined in the range of 0.0001-0.0007 min-1, and the activation energy values were determined in the range of 20.5-34.3 kJ/mol. β-carotene and lycopene content of tarhana samples decreased with the increase in drying temperature, and the rate of degradation reactions of these components increased with the increase in temperature and air velocity. As a result, it was determined that β-carotene and lycopene were better preserved at 1.25 m/s air velocity at 30 oC.

INVESTIGATION INTO THE POTENTIAL USES OF NONI (Morinda citrifolia) LEAVES AND STEM BARK

This paper investigates the potential uses of Noni (Morinda citrifolia) leaves and stem by examining their phytochemical components. The fresh Noni leaves and stems were processed using oven heat and air-drying methods, powdered, and stored to maintain sample integrity. The sample was then extracted with Acetone and tested for various compounds such as steroids, terpenoids, tannins, carbohydrates, alkaloids, flavonoids, saponins, cardiac, and glycosides. The results showed the presence of alkaloids, steroids, tannin, carbohydrates, terpenoids, glycosides, and flavonoids in both the leaves and stem bark. Additionally, various secondary metabolites were detected in different organic solvents, indicating that M. citrifolia contains bioactive compounds with potential medicinal applications. These findings are contributing to the growing global interest in Noni and suggest that it could be a valuable natural resource for treating various diseases.

The influence of different drying methods on bioactive components of Eucommia ulmoides Oliver male flower and the comprehensive assessment for industrial application

This study investigated the impact of different drying methods on Eucommia ulmoides Oliver male flowers (EUOMF), which were separately dried by hot air drying (HAD), microwave drying (MWD), and vacuum freeze drying (VFD) methods under different conditions. The results of HPLC showed that the geniposide (GP), and VB2 in the stamens were higher than those in the whole flowers. The contents of CGA, GPA, and GP in the stamens treated by MWD were 1.68, 1.52, and 5.88 times of those treated by HAD. However, compared with HAD, the destroy degree of free amino acid in MWD is up to 80%. VB2 and VE are the most damaged by VFD. The contents of VB2 and VE in the stamens treated by HAD were 11.5 and 1.85 times of those treated by VFD. Emphatically, principal component analysis indicated that the optimal drying conditions was MWD. Based on the economic efficiency, MWD is more suitable to produce the EUOMF tea than other methods for industrialization process.

Study on the drying condition optimisation of the heating pump and the infrared radiation for the snakehead fish Channa maculata

The paper focused on the drying condition of the infrared radiation combining the heat pump for the snakehead fish basing on the level 1 multi-factor experimental planning model of Box-Wilson. The results showed the mathematical model (Y = 8.92 + 0.44X1 - 0.53X2 - 0.48X3 - 0.098X1X2 - 0.39X1X3 + 0.126X2X3) that expressed the relationship between the drying time (Y) and the impact factors (the sorbitol concentration (X1), the drying temperature (X2), and the wind speed (X3), in which the drying temperature (X2) affected the drying time stronger than other factors. The optimisation condition of drying was the sorbitol concentration of 2.5%, the drying temperature at 57.5oC, the wind speed of 1.6 m/s, and the drying time of 8.27 hours. Dried snakehead fish at the optimum condition got the sensory quality, food hygiene, and safety higher than the air drying and sun drying methods. The results are a scientific basis for completing the technology and widely deploying the drying method in production.

Impact of different drying methods on the drying time, energy, and quality of green peas

The effect of seven drying methods (freeze (FD), hot air (HA), infrared (IR), microwave (MW), hot air‐infrared (HA‐IR), hot air‐microwave (HA‐MW), and sun drying (SD) methods on the drying time, the physical, qualitative and antioxidant properties, and the extraction of phenolic and flavonoid compounds in green peas was studied. Six mathematical models were also utilized to predict the moisture content of dried green peas. The results showed that the shortest and longest drying times were obtained by the HA‐MW and FD methods, respectively. For all drying methods, the Page model had the best ability in predicting the drying curve. The lowest amount of specific energy consumption was achieved by the MW method. The highest color changes and the lowest amount of shrinkage occurred in the FD method. The lowest rehydration ratio was 1.23 in the SD method. The highest pH value of 6.08 was also obtained in the SD method. The amount of antioxidant capacity changes and the total phenol and flavonoid contents varied between 42.47%–88.28%, 4.52–14.59 mg GAE/gDW, and 244.62–322.44 mg QE/gDW for different methods. The FD method was found to be the best way to preserve the product properties. It was further suggested that the HA‐MW method can be a promising technology for drying the green peas due to the relatively lower energy consumption, shorter drying time, and higher quality.

Antioxidant and Antitumor Properties of Wild Blueberry (Sideroxylon mascatense)

Background: Sideroxylon mascatense is a wild blueberry plant that traditionally known as “boot” in Oman. Studies on health beneficial effects of this fruit are very limited. Aims and Objectives: This study aimed to evaluate the antioxidant and antitumor properties of Sideroxylon mascatense under different drying methods. Materials and Methods: Freeze (−20°C) and air drying (60 and 90°C) methods were used. The antioxidant potential properties were evaluated using DPPH and ABTS assay. Moreover, the antitumor activities of blueberry extracts were determined using Alamar blue assay. Results: The results of this study revealed that a blueberry extract at 20 mg powder/mL provided the maximum amount of vitamin C, reaching a value of 19.45 mg/100 g dry-basis in the flesh dried at 60°C and 14.24 mg/100 g dry-basis in seed dried at 90°C. The freeze-dried blueberry exhibited the highest percentage of free radical scavenging activity (DPPH) from both fruit flesh (50.8%) and seeds (39.4%) at a concentration of 20 mg/mL indicating a higher antioxidant activity. There was no significant difference in the ability of blueberry extracts to scavenge radical cations (ABTS+) at various concentrations of extracts. However, there was a 40% reduction of ABTS+ radical formation in blueberry flesh extracts obtained from freeze-dried berry at a concentration of 20 mg/mL. On the other hand, blueberry seeds showed variation in the scavenging activity of the ABTS+ radical of 38% after different processing methods. Breast MCF7 and ovarian Ov2008 tumor cell lines were the most sensitive to the dried blueberry. The 50% growth inhibition (IC50) of the freeze-dried blueberry extract at both cell lines was 64 and 69 μg/mL, respectively. Conclusion: Our findings indicated a potent antioxidant activity of Sideroxylon mascatense, but further research is required to isolate the active compounds in the fruit and test their effects in an experimental animal model.

Nitrogen-Doped Mesoporous Carbon Microspheres by Spray Drying-Vapor Deposition for High-Performance Supercapacitor.

Nitrogen-doped mesoporous carbon microspheres have been successfully synthesized via a spray drying-vapor deposition method for the first time, using commercial Ludox silica nanoparticles as hard templates. Compared to freeze-drying and air-drying methods, mesoporous carbon with a higher packing density can be achieved through the spray drying method. Vapor deposition of polypyrrole followed by carbonization and etching is beneficial for the generation of ultra-thin carbon network. The mesoporous carbon microspheres possess a mesopore-dominate (95%) high surface area of 1528 m2 g−1, a wall thickness of 1.8 nm, and a nitrogen content of 8 at% in the framework. Benefiting from the increased apparent density, high mesopore surface area, and considerable nitrogen doping, the resultant mesoporous carbon microspheres show superior gravimetric/volumetric capacitance of 533.6 F g−1 and 208.1 F cm−3, good rate performance and excellent cycling stability in electric double-layer capacitors.

Stability of β-D-galactosidase immobilized in polysaccharide-based hydrogels

The stability of β-d-galactosidase immobilized in Arabic gum-based and chitosan-based hydrogels was studied during standard lactose hydrolysis reactions. Such studies were conducted considering freeze-drying and air-drying methods of the hydrogels, β-d-galactosidase immobilization capacities, pH values and temperatures of the aqueous enzyme solutions. The freeze-dried hydrogel was more suitable for β-d-galactosidase immobilization than the air-dried hydrogel. It was associated with the exposure of active sites in the porous hydrogel network. Higher β-d-galactosidase immobilization capacity was found using the chitosan-based hydrogel compared to the Arabic gum-based hydrogel. β-d-galactosidase immobilized in both hydrogels was submitted to five consecutive cycles of lactose hydrolysis. β-d-galactosidase activities in the hydrogels increased with the increase in pH and temperature. The exception was the hydrolysis reactions at 50.0 ± 1.0 °C, during which both the free and immobilized β-d-galactosidase exhibited minimal enzymatic activities, likely due to denaturation. Overall, the reaction temperatures for the free and immobilized β-d-galactosidase could be fixed at either 37.0 or 25.0 ± 1.0 °C. β-d-galactosidase immobilized in Arabic gum-based and chitosan-based hydrogels was more stable in acidic media than the free β-d-galactosidase. It is an excellent advantage for the application of β-d-galactosidase immobilized in both hydrogels.

Ultrasonic-Microwave and Infrared Assisted Convective Drying of Carrot: Drying Kinetic, Quality and Energy Consumption

In this study, the drying time, effective moisture diffusivity (Deff), specific energy consumption (SEC), and quality (color, shrinkage, and rehydration) of the ultrasound-pretreated (US) carrot slices were compared when dried by hot air drying (HD), microwave drying (MWD), infrared drying (INFD), and hybrid methods of MW–HD and INF–HD. Five mathematical models were considered to describe the drying kinetics in the carrots. The results show that US+MW–HD and INFD were the fastest and the slowest drying techniques compared to the HD technique with a 73% and 23% drying time reduction, respectively. The Deff ranged from 7.12 × 10−9 to 2.78 × 10−8 m2/s. The highest and lowest SECs were 297.29 ± 11.21 and 23.75 ± 2.22 MJ/kg which were observed in the HD and US+MWD, respectively. The color variation indices indicated that the best sample in terms of color stability was the one dried by US+MW–HD with the color variation of 11.02 ± 0.27. The lowest and highest shrinkage values were also observed in the samples dried by US+MWD and HD (31.8 ± 1.1% and 62.23 ± 1.77%), respectively. Samples dried by US+MWD and HD possessed the highest and lowest rehydration, respectively. Although the carrot slices dried at a higher pace by US+MW–HD (compared to US+MWD), the shrinkage and SEC of the samples dried by US+MWD were significantly lower than the US+MW–HD (p < 0.05). Therefore, it can be concluded that the application of the US+MWD method can be considered as a proper alternative for drying the carrot slices when compared to the HD, MWD, INFD, and hybrid methods.

Effects of drying methods on plant lipid compounds and bulk isotopic compositions.

Plant lipid biomarkers, such as plant waxes and terpenoids, and the stable isotopic composition of bulk leaves are widely used in both modern and paleoclimate studies for tracking vegetation and climate. However, the effects of different drying methods on the preservation of plant lipid biomarkers and the stable isotopic compositions of leaves are less explored. Here, we investigated various drying methods for the measurement of plant lipid concentrations and bulk leaf isotopic compositions. Leaves from four tree species (Acer rubrum, Pinus sylvestris, Platanus occidentalis, and Taxodium distichum) were collected and dried using air, an oven, a freeze-dryer, and a microwave. We compared concentrations of leaf waxes and terpenoids and carbon (δ13 C) and nitrogen (δ15 N) isotopic compositions of leaves by different drying methods. The air, oven, freeze-dryer, and microwave drying methods did not affect lipid concentrations significantly, and only a few homologues differed (38.1% or 41.8 μg/g on average) possibly due to biological variations or enhanced extraction efficiencies. The δ13 C values were not affected by drying methods, whereas the δ15 N values in oven-dried leaves in some species were higher by 0.2-0.7‰ than those obtained by other methods. Though small, we attribute these patterns to loss of leaf compounds with lower isotope ratios during oven-drying. Based on our results, each drying technique yielded equivalent results for all plant wax and terpenoid concentrations and bulk leaf δ13 C values; however, oven-drying modified the δ15 N values.

The Principles of Freeze-Drying and Application of Analytical Technologies.

Freeze-drying is a complex process despite the relatively small number of steps involved, since the freezing, sublimation, desorption, and reconstitution processes all play a part in determining the success or otherwise of the final product qualities, and each stage can impose different stresses on a product. This is particularly the case with many fragile biological samples, which require great care in the selection of formulation additives such as protective agents and other stabilizers. Despite this, the process is widely used, not least because once any such processing stresses can be overcome, the result is typically a significantly more stable product than was the case with the starting material. Indeed, lyophilization may be considered a gentler method than conventional air-drying methods, which tend to apply heat to the product rather than starting by removing heat as is the case here. Additionally, due to the high surface area to volume ratio, freeze-dried materials tend to be drier than their conventionally dried counterparts and also rehydrate more rapidly. This chapter provides an overview of freeze-drying (lyophilization) of biological specimens with particular reference to the importance of formulation development, characterization, and cycle development factors necessary for the commercial exploitation of freeze-dried products, and reviews the recent developments in analytical methods which have come to underpin modern freeze-drying practice.

Physicochemical properties, microstructures, nutritional components, and free amino acids of Pleurotus eryngii as affected by different drying methods

In this study, we determined the influences of different drying techniques such as natural air (ND), hot-air (HD), vacuum (VD), infrared (ID), microwave (MD), and freeze drying (FD) methods on the color, shrinkage ratio (SR), rehydration ratio (RR), firmness, crispness, microstructures, nutritional components, and free amino acids of Pleurotus eryngii. The results showed that these parameters were markedly influenced by different drying techniques. Among them, FD was the most effective drying method which retained the main characteristics of the fresh P. eryngii in above mentioned indexes, followed by ND and HD at 40 °C. Finally, despite the least drying time, MD treatment was not suitable to the drying process of P. eryngii slices since it damaged physicochemical properties and caused massive losses of the main nutrients and free amino acids. The results will provide a theoretical basis for industrial processing of P. eryngii.

New insights into Paeoniaceae used as medicinal plants in China

Paeoniaceae is an abundant germplasm resource with significant medicinal values in China, the principal medicinal components of which include paeoniflorin and paeonol. These compounds are typically obtained from air-dried root samples, which the use of freeze-drying as an alternative method has not been tested. Additionally, the presence of these two compounds in various wild Paeoniaceae species has not been previously explored, nor have the differences between various plant organs been fully evaluated. Here, freeze-drying and air-drying methods were compared to assess the changes in paeoniflorin and paeonol in root samples using ultra-performance liquid chromatography-mass spectrometer. The contents of these compounds in the roots, leaves, stems, and petals were then tested in freeze-dried materials. We also quantitatively detected the paeoniflorin and paeonol contents in the roots of 14 species collected from 20 natural habitats. Results indicated that the paeoniflorin content decreased under air-drying in comparison to freeze-drying, while the opposite trend was observed for paeonol. Our findings also demonstrated that the root xylem of species in Section Moutan, particularly Paeonia ostii, contains considerable paeonol and paeoniflorin and should thus be fully utilized as a medicinal resource. Furthermore, paeonol was mainly detected in the roots, while paeoniflorin was widely distributed in different organs; the highest content was in the leaf at the budding stage, suggesting that the leaves should be developed as a new paeoniflorin resource. Paeoniflorin contents were also found to be higher at earlier development stages. Based on the standards of the Chinese Pharmacopoeia, five species of Section Moutan and six species of Section Paeonia could be used as potential traditional Chinese medicinal resources. These findings of this study enhance our understanding of these two medicinal compounds and provide a foundation for the further development and utilization of Paeoniaceae as medicinal plant resources.

A note on sample drying method and natural moisture content of tropical red soils from the Republic of the Congo

This technical note describes the effects of drying method on the reported moisture content of tropical red soils from a case study site in the Republic of the Congo, Africa. Tropical soils are often considered to exhibit unique geotechnical characteristics which are often ascribed to the chemical compositions and micro-structures of a pedogenic material developed under hot, wet, soil-forming conditions. The applicability of conventional soil index tests for the identification and classification of such soils has therefore been questioned, primarily because of the dependence of such tests on the sample preparation process and the changes to the natural soil conditions which may occur during sampling and preparation. This holds true for determination of moisture content which, expressed as a proportion of the mass of the dry solid particles, can vary markedly, depending on the precise drying procedure undertaken. It is frequently suggested throughout the literature that air-drying methods, as opposed to conventional oven-drying, should be used to determine moisture content values for these soils. The findings of this study however suggest that, whilst such drying methods may be appropriate for certain tropical soils, a variation in the reported natural moisture content results may occur depending on the drying method used.

ADSORPTION ISOTHERMS OF KIWIFRUIT DRIED BY DIFFERENT DRYING METHODS

The aim of this study was to determine the moisture adsorption isotherms of kiwifruit dried by hot air, vacuum and freeze drying methods. Equilibrium moisture contents (EMC) of dried kiwifruits were obtained by using the standard gravimetric method at two different temperatures (25 and 45°C) within a range of water activities from 0.112 to 0.936. The adsorption isotherms of dried kiwifruits decreased with increasing temperature and exhibited type III behavior. Six different isotherm equations (GAB (Guggenheim-Anderson-de Boer), BET (Brunauer-Emmett-Teller), Oswin, Henderson, Halsey and Peleg) were employed to describe the experimental adsorption isotherm data. Adsorption data obtained at both 25 and 45°C for vacuum dried samples and data obtained at 45°C for hot air and freeze dried samples were best represented by Peleg equation. For the samples dried by hot air and freeze drying, GAB equation gave the best description of the experimental data obtained at 25°C.

The effect of different drying methods on the elemental and nutritional composition of Vernonia amygdalina (bitter leaf)

Vernonia amygdalina (VA) popularly known as bitter leaf is a common and popular vegetable in Nigeria used as a spice in many delicacies and as medicine. Most people believe that when vegetable like bitter leaf is preserved by the drying method, most of the essential minerals are lost. In this study, the effect of air, sun, oven and solar drying methods on the organic and dietary elemental composition of its leaves was evaluated using standard analytical procedures. Drying increased significantly the concentration of all the organic constituents evaluated. The ashed content was markedly enhanced by drying and it range from 2.56% in fresh sample to 11.20% in sun-dried sample, the fibre content range from 1.62% in fresh sample to 4.02% in air-dried sample, also the lipid content from 0.62% in fresh sample to 2.64% in air-dried sample. A significant increase in mineral content was observed upon drying except magnesium and copper whose concentrations were found to be high (48.23 and 0.31 mg/100 g) in fresh sample. The lead content also decreases upon drying, showing a way of reducing the quantity of lead intake. The concentrations of calcium and iron increased upon drying. The results of this study suggest that drying improves the concentration of both organic and dietary elemental constituents and oven–solar drying methods could be useful in preserving VA leaves in a more hygienic way and ensure its all-the-year round availability and possibly elimination of most nutrient deficiencies.

Assessment of Rhyzopertha dominica (F.) progeny and feeding damage on rice dried with infrared radiation

Infrared radiation (IR) is a method of drying grains that eliminates insect and microbial pests. It is unknown if IR could cause grains to be more susceptible to insects. Thus, the effects of IR on Rhyzopertha dominica development and feeding damage using long-grain rice varieties, Clearfield XL745 (hybrid) and CL152 (pureline), were examined. Rough rice was dried with three IR intensities: 2.15, 2.83, and 10.84 kW/m2. The number of progeny developed, feeding damage, and frass weight after IR-drying were compared with air-drying methods for rough rice and rice milled to brown rice after drying. Since R. dominica develop internally, X-ray technology was used to examine internal progeny and feeding damage. Progeny development and kernel damage appeared to be more affected by fraction (brown rice) than the cultivar of rice or intensity of IR used, with more progeny produced on brown rice than rough rice. An IR intensity of 10.84 kW/m2 increased the number of overall progeny, the amount of adults, and frass produced on CL152 brown rice. An intensity of 10.84 kW/m2 also increased the amount of larvae observed for both varieties and fractions. The intensity of 10.84 kW/m2, under the conditions of this study, is not recommended for drying rice.