Final Moisture Content Research Articles

Improving a technique for producing a polycomponent semi-finished product with high degree of readiness for 3-D printing of functional food

The object of this study is the process of producing polycomponent semi-finished products of a high degree of readiness using a model structure of functional equipment, in particular, based on apple, Jerusalem artichoke, table beet, and sea buckthorn. A feature of the improved technique is the implementation of preliminary heat treatment with hot steam of raw materials: apple – 1.0...2.0 min, Jerusalem artichoke – 3...6 min, and table beet – 6...12 min, respectively. Sea buckthorn was not processed, only technological rinsing was used. Grinding of raw materials was carried out on a double grinding machine (apple, Jerusalem artichoke, and table beet – 0.2...0.5 10-3 m, and sea buckthorn – 0.5...1 mm). The combined production of polycomponent semi-finished products of a high degree of readiness (pastes/fractional powder) was implemented using a model structure of functional equipment. The boiling process in a rotary-film evaporator was carried out at a temperature of 55 °C for 65 seconds to a dry matter content of 25 %. Drying of the cooked multicomponent mass was carried out in a single-drum cylindrical IR dryer at a temperature of 50 °C to a final moisture content of 3...6 % and fractional grinding (0.3...0.6 mm). The rheological properties of the paste-like multicomponent semi-finished product were determined by the change in dynamic viscosity for composition 2, which is 485 Pa∙s, and in the control sample of applesauce, this indicator is 50 Pa∙s. When boiling in a rotary-film evaporator at a temperature of 55 °C to a content of 30 % of dry substances, there is an increase in the strength of dynamic viscosity by 3.2 times (600 Pa∙s), and in the control (apple paste) this indicator is 178 Pa∙s with a dry matter content of 25 %

Potential Utilisation of Solar-Assisted Kiln Dryer in Bamboo Drying

Bamboo is increasingly used as an alternative material for producing renewable and environmentally friendly products. Bamboo should be dried before use to increase its stability and improve its resistance against biodeterioration agents. The most common drying method for bamboo is through air-drying. Alternatively, artificial drying, such as solar drying, can produce optimum drying results regarding the drying rate and quality of bamboo throughput. This study investigated the potential utilisation of solar drying methods for processing local bamboo. The drying characteristics and physical and mechanical properties of solar-dried Gigantochloa levis bamboo culms’ bottom, middle, and top sections were determined. The drying time of G. levis culm has been reduced to about 40 days compared to the conventional air drying of 70 days using the solar-assisted kiln dryer. Solar-dried culms have a lower final moisture content of 20% than air-dried ones. The average circumference and diameter shrinkage values of solar-dried G. levis culms from green to approximately 12% moisture content were 3.22% and 4.29%, respectively, and the wall thickness shrinkage was 8.12%. The mean values of modulus of rupture and modulus of elasticity of solar-dried G. levis culm were 63.75 and 12567.99 N mm-2, respectively, while its mean values of compression and shear parallel to fibre were 45.87 and 10.01 N mm-2, respectively. The quality of solar-dried G. levis culms produced in this study showed the viability of using a solar-assisted kiln-dryer as a potential alternative processing method for drying local bamboo species in Malaysia.

Mathematical modelling, energy consumption, and quality evaluation of wheat seeds subjected to intermittent drying

AbstractThis work aims to evaluate the kinetic profile of intermittent drying of wheat seeds using traditional models from the literature and the fractional calculus technique. Furthermore, it aims to verify the application of the intermittent drying process on the amount of antioxidant compounds, protein, and lipid content of the grain, in addition to energy consumption to obtain the desired final moisture content of the wheat. It was verified that the prediction of drying kinetics by Page and fraction order models were similar (modelling efficiency varying between the range of 0.917–0.995, varying the drying condition and wheat cultivar). Regarding antioxidant compounds for the three wheat cultivars, it can be seen that the higher fraction of ethanol (74.0% and 90.36%) used for extraction had greater process efficiency. Regarding the protein content in the three wheat cultivars, lower drying temperatures and intermittency periods result in lower quality losses of material (12.3% for BRS‐Atobá wheat, 9.89% for BRS‐Jacana wheat, and 18.71% for BRS‐Sanhaço wheat). In terms of lipids, it was found that the influence of temperature was greater on the lipid content than on the protein content of the material (for the best drying condition, there were percentage decreases for the best condition of 36.16% for the BRS‐Atobá wheat, 34.9% for BRS‐Jacana, and 52.2% for BRS‐Sanhaço). Regarding energy consumption during the drying process, it can be seen that the conditions used for intermittency and drying time, in addition to the sample conditions, directly impact energy consumption.

Unlocking the potential of pequi (caryocar brasiliense camb.): Stability of phenolic compounds, carotenoid profile and vitamin a after drying

Among the fruit species of the Brazilian cerrado is pequi (Caryocar brasiliense Camb.), recognized for its nutritional properties and profile of bioactive compounds. However, it is necessary to evaluate techniques that promote its stability, reducing the moisture content without degrading the content of natural antioxidants. Therefore, this study aimed to evaluate the drying of pequi pulp in an oven at different temperatures (40 °C and 55 °C), as well as determine its kinetics and influence on the content of bioactive compounds and antioxidant capacity. The increase in temperature showed a reduction (∼50 %) of the drying time, from 720 min (40 °C) to 360 min (55 °C), with a final moisture content of approximately 39 %, which is the optimized condition of the process. (360 min – 55 °C). Drying at 55 °C showed better retention of carotenoids (β-carotene, α-carotene, and β-cryptoxanthin), especially β-carotene, an important precursor of vitamin A, with retention of approximately 57 %. The results for antioxidant capacity (ABTS and DPPH), total phenolic compounds, total phenolic acids and total flavonoids confirmed that a longer drying time resulted in greater degradation of bioactive compounds, even at lower temperatures. The profile of phenolic compounds of the sample subjected to drying under optimized conditions was identified by HPLC-DAD-ESI-MSn, which showed the presence of six phenolic acids, one isoprenoid plant hormone, nine flavonols, and one flavonoid. Optimizing pequi pulp drying in ovens, and controlling time and temperature, can significantly reduce energy expenditure. This practice not only meets the demands of the food industry but also increases the use of fruits from the cerrado, promoting the diversification and valorization of these products.

Model Development and Experimental Application on Rewetting Characteristics of Cured Tobacco Leaves

Accurately predicting the moisture rewetting process of cured tobacco leaves is crucial for maintaining tobacco quality, storage stability, and preventing damage. In this study, a rewetting model for cured tobacco leaves was developed based on the two-component heterogeneity of leaf blades and main veins. The established model was compared with the model based on one-component homogeneity. The impact of different temperature and relative humidity (RH) conditions on the rewetting process of cured tobacco leaves was investigated, and predictions are made for the rewetting process on sunny and rainy days. In the results, the simulated value by the two-component heterogeneity model exhibited a highly consistent with the corresponding experimental data, with a maximum deviation of less than 9.74%. The rewetting rate increased with increasing temperature and RH, but the increased temperature also reduced the final moisture content. Compared to 20 °C and 80% RH, the rewetting time at 40 °C and 80% RH was reduced by 80.95%. The rewetting time at 20 °C and 90% RH was reduced by 81.25% compared to that at 20 °C and 70% RH. The rewetting rate of cured tobacco leaves was higher at night compared to daytime. In addition, the rewetting was faster on rainy days than sunny days. On rainy days (11.4–21.8 °C, 76.5%–95.4% RH), it took 13 h for cured tobacco leaves to reach the target moisture content (16% dry basis, d.b.) during rewetting, while on sunny days (20.3–29.5 °C, 46.1%–66.5% RH), it took more than 24 h. The findings of this study provided a helpful information for accurately predicting the moisture rewetting process of cured tobacco leaves.

Thermo-economic analysis of sun drying patio coffee in the Sierra Mariscal, Chiapas-México

This study shows a thermo-economic analysis of patio coffee drying in the Sierra Mariscal Chiapas-México to optimize bed thickness. The drying time, specific energy, thermal efficiency, water-effective diffusivity, and drying batch costs were correlated with bed thickness and solar irradiation. The initial and final coffee moisture contents were 53 % and 11–12 % (w.b). The bed thickness was in terms of kilograms of coffee uniformly spread on a square meter (2.0, 5.0, 10.0, 15.0, and 20.0 kg/m2). The five experimental campaigns involved five tests over a harvest season. The water-effective diffusion coefficient increases with bed thickness (0.38–91.2 × 10−10 m2/s). The solar irradiation requirement and the efficiency of the patio drying linearly increase with bed thickness while specific energy exponentially decreases. The lower specific energy was (7.1–10.4 MJ/kg) for the higher bed thickness (20.0 kg/m2), with (24.0–38.0 h) of drying time and (0.22–0.32) of efficiency. The optimized coffee bed thickness was 10 kg/m2, with a specific energy of 8.8–9.6 MJ/kg. When bed thickness increases, the thermal efficiency increases almost linearly 5.5 times, exponentially reducing the drying cost per batch five times. However, increasing drying times shall lessen the quality of physical-chemical and sensorial coffee.

Exergy and Energy Analysis of Forced Convective Thin-layer Solar Drying of Tiger Nuts (Cyperus esculantus L.)

Aims: To study the exergy and energy analysis for thin-layer solar drying of tiger nuts; and also to determine the drying kinetics for the thin-layer solar drying of tiger nuts. Study Design: Yellow variety of tiger nuts were dried in a forced convection solar dryer to determine the exergy and energy indices. Place and Duration of Study: Federal University of Technology, Owerri, Nigeria between October, 2022 to March, 2023. Methodology: The experiment was conducted at three different air velocities of 1.5, 2.5, and 3.5 m s-1 and two different loads of 70 and 140 g. The tiger nuts were dried from average initial moisture content of 52% (wb) to final moisture content of 10.2% (wb), at an average temperature range of 50.5 to 51.2 ºC. Energy utilization, exergy loss rate, exergy efficiency, improvement potential, and sustainability index were determined. Results: The results of energy utilization, exergy loss rate and improvement potential ranged from 2.1 to 5.09 W, 0.25 to 0.93 W and 0.08 to 0.54 W respectively; however, these values increased with increasing air velocities and loads. The results of exergy efficiency and sustainability index ranged from 41.8 to 68.49% and 1.72 to 3.17 respectively; these values increased with decreasing air velocities and loads. Graphical plots of moisture content with drying time showed that the moisture content of the tiger nuts decreased with increasing drying time. The characteristic nature of the curve is indicative of the fact that there was an initial higher rate of drying, which gradually declined with drying time. The results also showed that the drying rates of the tiger nuts ranged from 6.03 to 8.44 %MC/hr; and these values varied with the different air velocities and loads. Conclusion: The results from this research will serve as a guide in reduction of energy costs for the optimum design of convective dryers.

Dewatering promoting of carbon-rich coal gasification coarse slag by size reduction with surface modification

ABSTRACT Coal gasification coarse slag (CGCS) has become a bulk coal-based solid waste that threatens the ecological environment. The high moisture content of carbon-rich coal coarse gasification slag (CR-CGCS) seriously limits its utilization. In this study, a pore water releasing method was proposed to promote the dewatering of CR-CGCS through size reduction with surface modification. Hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and kerosene were added during the grinding process, respectively. The results showed that kerosene can significantly improve the dewatering efficiency of CR-CGCS more than CTAB and SDS. The final moisture content of the CR-CGCS could be reduced from 47.50% to 33.01%. The SEM and FTIR results illustrated that kerosene could effectively reduce the content of oxygen-containing functional groups on the surface of CR-CGCS more than CTAB and SDS. Meanwhile, the PVM results showed that CR-CGCS modified by kerosene tended to form hydrophobic agglomerates. The LF-NMR results indicated that only the water in the macropores of CR-CGCS could be released in grinding process, but the water in micropores could be reduced when kerosene, CTAB, or SDS was added in grinding. This study provides new insight into enhancing the dewatering of CR-CGCS and theoretical support for the efficient utilization of CR-CGCS.

Assessment of a beeswax-packed domestic solar dryer for sustainable bitter gourd drying: An experimental study

Solar dryers present a clean and affordable solution to food wastage which is one of the biggest concerns of the world. The highest contribution of domestic sector to the global food waste and lack of researches on small-scale solar dryers have created a need to develop sustainable and low cost domestic solar dryers. The present research aims to develop and analyse the output behaviour of a beeswax-packed domestic solar dryer (BDSD) for intermittent bitter gourd drying. The drying kinetics of bitter gourd slices and thermal, economic, environmental and exergetic performances of the BDSD have been evaluated with varying sample masses for passive and active drying conditions. The average final moisture content of the bitter gourd slices for passive and active conditions were found to be 3.26 and 3.93 % (wb), respectively. Midilli-Kucuk model exhibited the strongest fit to the bitter gourd drying behaviour under both the drying conditions. The total moisture evaporation, heat transfer coefficients, thermal efficiency, specific moisture extraction rate, savings for dried bitter gourd slices drying, CO2 mitigation, carbon credit earned and exergy efficiency were found to increase while the drying rate, effective moisture diffusivity, specific energy consumption, costs for bitter gourd slices drying, payback period and energy payback time decreased as the sample mass increased under both drying conditions. The performance of the BDSD was found to be a linear function of sample mass under both drying conditions.

Optimizing the secondary drying phase of a continuous Spin-Freeze Drying process: A semi-mechanistic modelling approach

Over the past decade, continuous spin freeze-drying technology has emerged as a promising alternative to conventional batch freeze-drying, effectively addressing many of the latter’s inherent disadvantages. Much of the focus during this period has been on controlling and optimizing the primary drying phase of this process. However, optimizing the secondary drying step is equally critical for the overall efficiency of the process. The primary aim of this study was to develop a comprehensive semi-mechanistic model for the secondary drying phase in continuous spin freeze-drying, accounting for the effects of process settings such as freezing rate and product temperature on desorption kinetics. Additionally, the study aimed to address discrepancies between conventional desorption models, typically applied in batch freeze-drying, and the observed data in this research. To achieve this, a residual moisture-dependent activation energy was introduced to improve the accuracy of the desorption model. Using NIR spectroscopy and IR-thermography, unknown model parameters could reliably be estimated using a simple and fast procedure. The calibrated model successfully predicted the final moisture content with an accuracy within 0.11% of the measured value under previously untested process conditions. Ultimately, the proposed semi-mechanistic model demonstrated its reliability in predicting the impact of new process conditions on both product temperature and residual moisture over time, enabling the development of a practical design space.

Prediction model of moisture content in spray drying of ceramic slurry based on IMFO-BPNN

The final particle moisture content of ceramic slurry spray drying affects the processing, product quality, and process energy consumption. While the real-time moisture content determination is very difficult for spray drying process due to nonlinear, severe lag, interference factors, and complexity of the systems, the high temperature, high humidity drying environment and short drying process. In current work, an improved moth optimization (IMFO) algorithm combined with backpropagation neural network (BPNN) was proposed to predict the moisture content of ceramic slurry particles during spray drying. The performance of the model is trained and tested. Results demonstrate that IMFO has better convergence ability and speed compared to other algorithms such as particle swarm optimization (PSO) and gravitational search algorithm (GSA). The IMFO-BPNN model achieves a MAE of 0.0293, RMSE of 0.0383, and R2 value of 0.9113, outperforming the prediction performance of BPNN and MFO-BPNN models. The absolute error rate of the IMFO-BPNN model (0–5%) is lower compared to BPNN (5–10%) and MFO-BPNN model (>10%), showcasing superior accuracy in predicting moisture content. This mathematical model established in the study provides an efficient, accurate, and nondestructive method for predicting the drying endpoint of ceramic slurry spray drying.

Investigating drying behavior and quality of Neem leaves using a novel biomass gasification-powered climate control unit with built-in humidity control

Traditional food drying methods, such as open sun drying (OSD) and hot air convective drying (HAC), are widely employed due to their simplicity. However, these methods are inefficient and often yield lower-quality and contaminated products. To address these limitations, we utilize a novel Climate Control Unit (CCU) powered by biomass gasification. The CCU allows independent control of temperature ranging from 0−70°C as well as humidity 10−90%. Our primary objective was to investigate the various drying methods to preserve essential nutrients, reduce power-consumption, and promote environmental-sustainability. In this study, we focused on Neem leaves, a valuable medicinal ingredient, and investigated their drying behaviour and quality using the CCU as a dryer. We implemented diverse control strategies, including temperature control, humidity control, and combined temperature and humidity control. The drying experiments were conducted across different temperature ranges: moderate 45−55°C15−30%, low 25−35°C15−30%, and high 65−75°C15−30%. For comparison, we evaluated the results against OSD and HAC. Next, we assessed various thin-layer drying models to describe the optimal drying kinetics of Neem leaves. Furthermore, we focus on quality aspects, including chlorophyll, phenolic, and tannin content and the thermal performance of the system. Overall, our study elucidates the need to balance drying time and product quality while selecting drying methods. Moderate temperature with humidity control drying appeared to be optimal with a slight compromise on drying time (final moisture content ≈13%drybasisin7hours, and preserving chlorophyll (≈95%) and phenolic content (≈55%)); however, high-temperature drying seemed optimal with a slight compromise on product quality (final moisture content ≈6%in3hours, and preserving chlorophyll (≈70%) and phenolic content (≈45%)). The peak drying efficiency of ≈21%, ≈28%, and ≈38% was obtained during temperature, humidity, and combined temperature and humidity control at moderate temperature drying respectively. The drying cost (≈0.29 $/kg) was observed minimal in case of combined temperature and humidity control. We believe the diverse control strategies reported in this study are expected to find viable applications in drying technology for various perishables, such as wood, tea seasoning, and processing in leather industries, among others.

Effect of Oats and Millet composition in Gluten-free Nutrient wafer

Pearl Millet [Pennisetum glaucum (L.)] is a widely cultivated staple crop and nutritionally rich cereal grain. The cultivar can tolerate drought and high temperatures, making it suitable for arid and semi-arid regions, especially in Africa and Asia. Millet-based products have numerous health benefits like lowering cholesterol, managing blood sugar, and many others. It is rich in antioxidants, fiber, and various micronutrients. Millet is gluten-free, suitable alternative for individuals with gluten intolerance or celiac disease. Methods: Low-sugar-gluten-free Pearl millet wafer is a low-moisture baked food prepared from a mixed batter of millet powder, and oats. A waffle iron toaster (1000W) is used to prepare the wafer The nutritional components were analyzed and calorie calculation was done following the Atwater system. The total energy from a 100 gm wafer serving was found to be around 289 calories. Results and Discussions: The product was typically shaped in a square-grooved sheet, with a density around 0.2gm/cc, the matrix is aerated and fluffy. Total final moisture, ash and extracted fat content was also estimated. The average thickness of the wafer was around 5mm. Sensory parameters like crispiness, chewiness and mouthfeel were evaluated on a hedonic scale while the crispiness is correlated to the final moisture content. Product cost was calculated including the energy cost calculation. The cost of the final product was Rs 45/100gm which is at per the marketed wafers. Conclusion: The improved quality was targeted to achieve in a model of low-emission process to reduce the energy cost and increase production efficiency with better nutritional component retention.

Improvement of Antioxidant Activity and Sensory Properties of Functional Cookies by Fortification with Ultrasound-Assisted Hot-Air-Drying Blackberry Powders.

In response to the global challenge of food wastage and high perishability of blackberries, this study evaluated the use of ultrasound-assisted hot air drying (US-HAD) to convert downgraded blackberries into powders, comparing it with traditional hot air drying (HAD). US-HAD reduced the drying time and achieved a final moisture content of 12%. Physicochemical analyses (colourimetry, total soluble solids, titratable acidity, and total phenolic content) were conducted on fresh fruit, powders, and fortified cookies. US-HAD cookies exhibited promising antioxidant activity, with ABTS values ranging from 8.049 to 8.536 mmol TEAC/100 g and DPPH values from 8.792 to 9.232 mmol TEAC/100 g, significantly higher than control cookies. The TPC was 13.033 mgGAE/g in HAD cookies and 13.882 mgGAE/g in US-HAD cookies. UHPLC-ESI-MS analysis showed an increase in phenolic compounds content in fortified cookies compared to the control. Sensory analysis highlighted a superior blackberry flavour and overall acceptability in US-HAD cookies, with statistical analysis confirming their superior nutritional and sensory qualities. Integrating US-HAD blackberry powder into cookies helps reduce food waste and enhances the nutritional profiles of baked goods, offering functional foods with health benefits. This work provides a scientific basis for developing enriched functional cookies, offering a healthy and sustainable alternative for utilising damaged fruits.

Air-drying performance of three genotypes of teak wood

The clonal materials of Tectona grandis L. f. in fast-growing plantations exhibit faster growth than the seminal materials. Therefore, it is necessary to investigate the differences in wood drying to ensure the quality and yield of the final product. This study evaluated the outdoor drying behavior of three genotypes of teak lumber. Two clonal genotypes (G1 and G2) and one of seminal origin (G3) were assessed. Boards measuring 30 × 150 × 1000 mm (thickness × width × length) were produced from the basal logs. The average moisture content (79.3, 64.9, and 60,1%), final moisture content (10.8, 9.8, and 11.6%), and mean drying rate (1.2, 0.97, and 0.85%.day-1) were observed in the wood from genotypes G1, G2 and G3, respectively. The clonal material crooked and bowed below 5 mm.m-1, which is considered the tolerance limit for both warpings. The seminal material had a greater incidence of splitting. The clonal genotypes G1 and G2 had similar qualities and presented higher drying rates, final moisture contents below 11% and a lower incidence of defects, especially splitting, compared to the naturally seeded material.

Drying behavior and nutritional quality of bitter‐gourd slices dried in a solar dryer with tray and skewer arrangement

AbstractIn this investigation, we assessed the efficacy of an indirect‐type solar drying system that utilized skewers and rack arrangements, comparing it to a conventional drying cabinet equipped with trays for dehydrating bitter gourd slices. We examined the influence of pretreatment methods and loading quantities on the solar drying process for bitter gourd slices in both configurations. The drying behavior of various combinations was scrutinized, and the physicochemical attributes of the dried bitter gourd samples, including total phenolic content, total flavonoid content, total chlorophyll content, antioxidant capacity, ascorbic acid content, and color, were analyzed. Rehydration characteristics, such as rehydration ratio, coefficient of rehydration, percent water in the rehydrated sample, and hardness of the rehydrated sample, were also determined. The bitter gourd slices achieved a final moisture content of 6.84%–8.27% wb after drying from an initial range of 88%–90% wb, within a total elapsed time of 28–55 h. The solar drying cabinet utilizing skewers exhibited enhanced efficiency, featuring reduced drying time and superior product quality compared to the tray‐equipped drying cabinet. This improved performance is ascribed to enhanced hot air circulation over the produce surface, facilitated by the uniform spacing between skewers on racks within the drying chamber.

Effect of combined dialysis method on dewatering of coagulant pretreated sludge

The unique composition and condition of sludge pose significant challenges in water removal. Therefore, it is crucial to investigate a cost-effective and highly efficient approach for dehydrating sludge. In this paper, the domestic sludge was respectively pretreated with ferric chloride, polyaluminum chloride, and cationic polyacrylamide. Then the pretreated sludge was performed on gravity dehydration, centrifugal dehydration, dialysis dehydration and mixed method. The effect mechanism of coagulant and dewatering method on sludge dehydration was analyzed from micro perspective. Finally, the influence range of the dialytic solution was tested by model experiment. The results indicate that the dehydration efficiency of the pretreated sludge with PAC is slightly better than that pretreated with FeCl3 and CPAM, and the optimal dosage of PAC is 8 %. The effect of dialysis dehydration is the best, which can significantly change the final moisture content of sludge (much less than 60 %), effectively achieving the requirements of subsequent processing. The water content of the sludge treated by gravity dehydration, centrifugal dehydration and dialysis dehydration can reach 38 %, which is much smaller than that of the sludge treated by a single dehydration method. The free water, occlusion, coating water, and bounding water are dehydrated by gravity, centrifugal force, and dialysis. The influence range of dialysis dehydration is less than 10 cm. When the distance is more than 10 cm, the difference of sludge moisture content at different relative heights is larger. The study has certain theoretical guidance significance for improving the performance of sludge concentration and dewatering.

Sorption Drying of Wheat Seeds Using Kieserite as a Solid Desiccant

The moisture content (MC) of wheat seeds must be reduced before storage using appropriate dehydration processes. Desiccant drying is a promising alternative to conventional drying methods because it improves seed quality while providing overall energy efficiency. This study explores the sorption drying of wheat seeds using granulated kieserite MgSO4·H2O as a solid desiccant, which has a high water capacity and is regenerated at low temperatures <100 °C. Desiccant characterization was conducted using SEM-EDS, XRD, DSC-TG, and particle size analysis. Wheat seeds mixed directly with kieserite in various mass ratios were dried under uniform stirring and controlled temperature conditions. A 240-min drying time was required to reduce the initial MC of wheat from 21.5% to 15.1% at a desiccant-to-grain ratio of 1:1. After 360 min, a final MC of 14.4% was achieved. The germination energy and seed capacity after sorption drying were 91 ± 1% and 97 ± 2%, respectively. Due to the available water capacity of kieserite, several batches of seeds can be dried without intermediate desiccant regeneration. This study is useful for developing low-cost, non-thermal, and sustainable drying technology for various agricultural products.

Effects of hydrothermal–microwave treatment on bending properties of teak in plantation

In order to study the bending properties of tropical tree species rich in organic extracts, the effects of temperature and time on the bending performance of hydrothermal treatment were investigated. The effects of power and time on bending performance under microwave heating conditions were investigated. It is found that the chemical composition does not undergo obvious degradation at 80°C–100°C, and the bending performance gradually becomes better with the increase in heating time; when the hydrothermal time exceeds 4 h, the bending performance varies with heating time. The growth is better than the difference, reaching the maximum at 4 h. When the water temperature is 140°C, the bending performance is negatively correlated with the heating time. When the hydrothermal treatment time is the same, the bending property becomes better as the temperature increases. The most reasonable process for microwave softening heating is with a power of 480 W and a heating time of 4 min. A softening treatment method combining water heat and microwave can achieve a better softening effect. When the final moisture content is controlled to 8%, the bending setting effect is the best. The optimum drying time is 6 h, and the optimum drying temperature is 50°C.

Microwave-assisted hot air drying of Cannabis sativa: Effect of vacuum and pre-freezing on drying kinetics and quality

Drying is an important postharvest step preceding long term storage of medicinal plants, and optimized drying conditions are critical for secondary metabolite preservation. The objective of this research was to determine the effect of pre-freezing, vacuum, drying temperature, and microwave power on cannabis, including drying kinetics, color retention, and moisture diffusivity, and cannabinoid and terpene concentrations. Harvested inflorescence was dried under four drying conditions, namely untreated, dried without vacuum, untreated, dried with vacuum, pre-frozen, dried without vacuum, and pre-frozen, dried with vacuum. The untreated groups were dried and analysed immediately after harvest and the pre-frozen group was frozen at −20°C for 24 h prior to drying and analysis. Results showed that moisture diffusion was significantly affected by the temperature, vacuum and microwave power and reduced exponentially with time. For untreated samples dried at a microwave power of 2 W g−1, it took only 61 min (with no vacuum) and 57.3 min (under vacuum) at 65°C to reach the desired final moisture content of 11 % dry basis. Increasing drying temperature from 35°C to 50°C at 1 W g−1 under vacuum reduced the drying time by 60.1 % and 68 % for pre-frozen and untreated samples, respectively and reduced by 68 % and 65.5 % for pre-frozen and untreated cannabis samples, respectively for samples dried without vacuum. Pre-freezing prior to hot air drying with and without vacuum can be used to preserve the color of biomass and cannabinoids. The effect was prominent in the acidic cannabinoids where pre-freezing prior to hot air drying at 50°C without vacuum increased tetrahydrocannabinolic acid and cannabigerolic acid concentrations from 20.6 to 23.6 g 100 g dry matter−1 and 0.47–0.61 g 100 g dry matter−1. Results presented add important knowledge for the optimization of postharvest steps for cannabis.