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The present study aimed to select the mathematical models that best fit the drying kinetics of maize seeds on the cob. A 50- and 150-cm maize layer was used in the dryer for four airflows: 5. 10, 15 and 20 m 3.min -1.t -1 was used for stationary drying. The ears were dried in four prototypes of stationary perforated false-bottom dryers with a diameter of 0.92 m, height of 1 m and axial fan. The temperature of the drying air was controlled at the base of the dryer chamber using a thermostat. The mathematical models were analyzed via linear regression. The model of Page and Handerson & Pabis was used. The results showed that the Page model was more satisfactory for predicting the data for the 50 cm layer of ears than the Henderson & Pabis model was for predicting the data for the 150 cm layer. However, both models can be used to represent the drying phenomenon of maize seeds on cobs

Pepper is a vegetable of the Solanaceae family, extensively cultivated in Brazil. After the extraction process, pepper seeds have high moisture content and need to go through a drying process. The study of drying kinetics is extremely important for the simulation and development of drying equipment, essential items for maintaining seed longevity. The objective of this work was to determine and model the drying kinetics of sweet pepper seeds (Capsicum chinense) under drying conditions in the shade, at 30 and 40°C. For this, sweet pepper seeds were subjected to the drying process under three conditions: shade, at 30 and 40 °C (forced circulation oven). The pepper seeds, with an initial water content of approximately 70% (wet basis), were weighed at intervals of one hour until reaching the equilibrium moisture content. Eight mathematical models were adjusted to the experimental data to characterize the drying processes, in which statistical criteria were used (determination coefficient (R²), estimated mean error (SE), chi-square test (χ²) and residue distribution) for selection of the best model. The model proposed by Page is the one that best represents the drying kinetics of sweet pepper seeds. [ABSTRACT FROM AUTHOR]

Lulo (Solanum quitoense Lam.) is an exotic fruit with high potential in international markets due to its intense aromatic characteristics and its content of nutritional and bioactive compounds. However, it is highly perishable, which backslashes its potential for international exportation. Despite the drying processes affect the nutritional and sensory characteristics, fruit powders obtained by spray drying are promising products for the food, cosmetic, and pharmaceutical industries. This work was conducted aiming to optimize the spray-drying process of lulo pulp. A Box-Behnken design with response surface methodology was used, in which the factors evaluated were inlet air temperature (160 - 220 °C), maltodextrin concentration (15-35%), and whey protein concentration (WPC) (1-5% w/w). The feed rate and air velocity were kept constant at 4 mL/min and 9 m/s, respectively. The optimization resulted in an inlet air temperature of 205.6 °C, 35% maltodextrin, and 1.96% WPC. Under these conditions, the mathematical model estimated a powder yield of 62.8%, a moisture content of 2.3 %, a bulk density of 0.49 g/mL, a solubility of 91.9 %, and an ascorbic acid content of 120.8 mg/100 g powder. The optimal process conditions and the mixture of encapsulants (MD and WPC) allow for obtaining lulo powder with adequate yield and quality characteristics.

ABSTRACT This study aimed to evaluate, on a real production scale, the management of batches of harvested soybean grains in storage units, which are submitted for different technological processes of drying. The study regions were divided into micro-regions based on structure and static storage capacity. For each micro-region (West, East, North, South, Central), soybeans were dried using a continuous dryer-CD1, a continuous dryer + silo-dryer-CDSD2, and a continuous dryer + aerator-silo-CDAS3. Grain quality losses due to drying management ranged from 0.23 to 3.26% in crude protein, and from 0.15 to 3.05% in crude oil. In regions with large-scale soybean production, adopting storage unit structures at the farm level, ranging from 11 to 19 km, with high drying technology in partial continuous grain flow and final stationary drying in a silo-dryer or silo-aerator is the best alternative for a productive-sustainable system. Managing CDSD2 and CDAS3 soybean drying system is an alternative that ensures low losses and high grain quality, improving protein and crude oil content. In conclusion, the CDSD2 and CDAS3 drying systems reduced crude protein and oil content losses by 94% and 95%, respectively, providing a much better sustainable postharvest system.

ABSTRACT The genus Psidium is recognized for its economic value and the species that produce essential oils with notable biological activities. This study investigated the characteristics of the essential oil from the leaves of Psidium myrtoides and Psidium cattleyanum under different drying temperatures. We aimed to understand how drying temperatures affect the yield and composition of the essential oil, as well as its biological activity. The oils obtained from the leaves of P. myrtoides and P. cattleyanum dried in an oven at 40°C showed the highest yields (0.86% and 1.07%, respectively). β-caryophyllene was the major compound in all essential oils of P. myrtoides and P. cattleyanum, except in the oil extracted from P. myrtoides leaves dried at room temperature, where the major compound was α-bisabolol (14.46%). Different phytotoxic effects were observed using the emulsion of these oils in bioassays with Lactuca sativa and Sorghum bicolor, which were associated with the chemical composition and synergy of the identified compounds. The essential oil emulsion from leaves dried at room temperature of both species showed greater phytotoxic activity in the bioassays. Thus, optimizing drying conditions to maximize yield and synergy of compounds from the essential oils of P. myrtoides and P. cattleyanum is an important step in developing environmentally friendly natural agrochemicals.

ABSTRACT The structural parameters of a grain dryer are directly related to the its energy consumption and quality formation. Therefore, based on the Ergun model, air state parameters and uniformity evaluation method, the effect of changes in the ventilation area on grain airflow resistance, drying energy consumption, drying efficiency and uniformity are theoretically and experimentally studied in this work under the same initial grain weight and air flux. The results show that under the conditions of air temperatures 35℃ and 70℃, the weight of paddy 8.547 kg and the air flux 12.3 m3·h-1, hot air introduced into the drying chamber with cross-sectional areas of S1 and S2 respectively, the ventilation area enlarged by 2.328 times, the grain airflow resistance decreased by 7.17 and 6.99 times. Enlarging the ventilation area effectively improved the drying rate of paddy, especially at 70℃, while the unit energy consumption was the opposite. It also accelerated the moving speed of the saturated humidity line in the drying layer and improved the drying uniformity of the paddy. These experimental results are in agreement with the theoretical analysis, which provides a reference for the design of grain drying equipment and technology.

ABSTRACT This study aimed to evaluate the duplicity and synergism of slow drying and storage processes at low temperatures, using a refrigerated room under suitable conditions for coffee fruit just after harvest. A cold room was prepared to receive and store coffee fruit in bulk directly from the field, perform slow drying, and maintain water content at approximately 12% during three months of storage. The room operated at temperatures between 7 and 14 ºC and relative humidity between 37 and 41%. The coffee variety used was the Conilon Yellow 62. The initial water content reduction period from 54% (wb) to 12% (wb) was two months. For comparison, coffee harvested from the same batch was dried on a covered suspended bed. Results showed that the coffee dried and stored in the cold room received a sensory score of 86.41, while that dried on a suspended bed obtained a sensory score of 84.16. Moreover, the coffee dried and stored in the cold room had a higher energy content. Colorimetric analysis showed that the dried grains stored in the cold room had a reduction in the "a" coordinate, indicating an approximation to the green color. The cold room also allowed for extended storage of the coffee grains.

ABSTRACT Charcoal fines are co-products of the wood carbonization process, unwanted because they reduce the gravimetric yield of the main product, charcoal. It can be produced due to the carbonization process, during the storage and transport of charcoal. Pelletizing charcoal fines increases the energy density of this material, producing a homogeneous fuel with lower moisture content, enabling burning in equipment with high energy efficiency, in addition to desirable properties in energy products such as high fixed carbon content and low moisture content. This study evaluated the effect of moisture content and drying time on the production of black pellets from charcoal fines bound with rice starch (Oryza sativa) on the physicochemical and mechanical characteristics. Black pellets were produced using two proportions of water (10 or 20%) and a drying time of 4 or 6 hours. Black pellets were evaluated for their proximate analysis, elemental composition, moisture content, size, apparent density, calorific value and energy density. The addition of water did not affect the content of volatile matter, ash, and fixed carbon, while the treatment with addition of 20% water and four hours of drying showed a higher moisture content (3.34%). The addition of water allowed for better heat conduction and particle arrangement, producing pellets with a durability greater than 98%. The better arrangement promoted by the addition of 20% water also increased the density of the pellets, resulting in greater energy density. Black pellets can be considered an alternative for residential heating, with T3 treatment (20% - 4h) with a high energy density and better performance in terms of desirable properties for use and commercialization according to the standard EN 14961-6.

ABSTRACT Yacon, a perennial plant from the Andean region, is particularly rich in fructo-oligosaccharides (FOS) and inulin. However, these saccharides are rapidly hydrolyzed after harvest, affecting the functional characteristics of yacon. Therefore, a preservation technology such as drying is warranted to preserve the FOS content of yacon products during the off-season. To this end, we dried yacon slices, either untreated or pretreated with pulsed vacuum osmotic dehydration (PVOD), in a microwave vacuum (MWV). PVOD was performed using a sorbitol solution (38 °Brix, 35 °C, and 681 mmHg during the first 10 min). A three-level experimental design with three initial power densities (PDs) of 3.6, 6.3, and 9.9 W.g−1 and three vacuum pressures (VPs) of 0, 300, and 600 mmHg was employed to perform the MWV drying experiments. FOS content, drying kinetics, diffusivity, shrinkage, yacon temperature, and rehydration were investigated. We observed that during PVOD, as microwave PD increased, the drying time, moisture, and water activity decreased. Moreover, an increase in PD positively affected FOS retention, diffusivity, temperature, and shrinkage. Furthermore, VP significantly affected FOS retention in pretreated samples and facilitated drying. In addition, microwaves with a higher PD increased the effective diffusivity and facilitated FOS retention. VP also affected the drying and FOS retention of pretreated samples. In general, yacon browning was observed under all treatment conditions, independent of pretreatment. For osmotically dehydrated samples, processing conditions with a PD of 9.9 W.g−1 and vacuum pressure of 600 mmHg are ideal for drying yacon slices via microwave vacuum, thereby increasing the FOS content by approximately 40%.

Abstract The influence of various drying characteristics in the experiment was explored in this study. The drying time and moisture content were used to evaluate the experimental outcomes. The drying of bitter gourd slices using a halogen dryer was done at varied thicknesses (3, 5, and 7 mm) and temperatures (60 °C, 65 °C and 70 °C). The results revealed that the drying time and equilibrium moisture content are considerably affected by the material drying thickness and drying temperature. Furthermore, the Generalized Regression Neural Network (GRNN) model is employed in this study to train and predict the moisture content of bitter gourd as an output parameter. The temperature, bitter gourd thickness, and drying time were considered as input parameters for the GRNN model. Three statistic measures as the R-square, the Root mean square error (RMSE) and the Mean relative percent error (P) were used to validate the accuracy of the trained GRNN model. In training with nine experimental condition datasets, the average score values of R-square, RMSE and P were obtained at 0.995197, 1.498966 and 0.091617, respectively. The test of trained GRNN has been conducted with good agreement between experimental data points and predicted points. The result revealed that GRNN was effective in predicting the moisture content of bitter gourd in a halogen dryer.

ABSTRACT Soybean seeds (Glycine max) were dried under real scale conditions to different final moisture content (m.c.) (9.1, 9.7, 10.9 %, and control with 16.2 %) and processed through extruding-expelling. Results indicated that soybean seed m.c. affected the composition of the soybean expeller and, thus, the oil extraction efficiency (OEE), which increased as the seed m.c. decreased. A polynomic model was proposed for predicting OEE as a function of soybean m.c., indicating that drying soybean to 10 % resulted in an OEE of approximately 65 %. A thin layer drying experiment of soybean seeds indicated that the protein dispersibility index (PDI) was not affected as regards drying air temperatures up to approximately 69 °C, and a bi-linear model with a non-pre-established break point was fitted. The real scale drying treatment in a rack type dryer (mixed flow) did not show any effect (p > 0.05) on the PDI at 80 °C, while at 115 °C a reduction (p < 0.05) was observed (PDI reduction was 0.8 and 2.1 percentage points, respectively).

ABSTRACT: The drying agroindustrial products is used to preserve the sensory and nutritional quality and to reduce the biological activity, preventing deterioration and loss of commercial value. The objective was to study the mathematical modeling Guava bark drying to obtain flour and to determine and evaluate the effective diffusion coefficient, get the activation energy and the thermodynamic properties in drying temperatures of 45, 55, 65 and 75 °C. The experiment was conducted Instituto Federal Goiano - Campus Rio Verde, the guava was purchased in local shops in the city of Rio Verde Goiás, in the commercial maturity. Among the analyzed models, Midilli was the best to represent the drying phenomenon. The effective diffusion coefficient increased with increasing temperature and the activation energy for liquid diffusion drying was 37,207kJ mol-1. The enthalpy and entropy increased with increasing drying temperature. While the Gibbs free energy increased with increasing drying temperature.

ABSTRACT High-sugar dehydrated foods have strong hygroscopicity, which can be avoided by using drying aids. One way to assess the hygroscopic behavior is through sorption isotherms. The objective of this work was to evaluate the influence of maltodextrin concentration on sorption isotherms of powdered cajá-manga pulp in spray-dryer, lyophilization and fluidized bed spray drying processes. The dryings were carried out in a spray-dryer, lyophilizer and fluidized bed, with 10%, 20% and 30% of maltodextrin. Adsorption isotherms were determined by the static gravimetric method using salt solutions for a relative humidity range of 21% to 90%. The GAB, BET, Henderson, and Oswin models were adequate to the experimental data. The relative deviation between the experimental values and the estimated values was calculated for each curve, in order to assess which equation best fit the experimental data. The mean relative error value of less than 10% was considered one of the criteria for selecting the models. The BET (A), BET (B) and GAB (C) models had the lowest error means, 3.35%, 3.35% and 5.28%, for cajá-manga powders obtained by spray-dryer, lyophilization and fluidized bed spray drying processes, respectively, and coefficients of determination above 0.99. It is concluded that the type of drying process did not influence the behavior of the adsorption isotherms, and that increases in maltodextrin concentration and temperature are significant in reducing equilibrium moisture contents.

ABSTRACT The Peruvian carrot is a root that is rich in bioactive compounds. However, owing to the short shelf life of these carrots, their consumption is restricted. In the present study, we investigated the microwave vacuum drying (MWVD) of restructured Peruvian carrot chips. Two microwave power levels, namely, constant and two-stage, were considered and evaluated to determine their relationship with drying time, kinetic parameters, energy consumption, and preservation of carotenoids and phenolic compounds. At the constant microwave power level, drying time decreased with increasing drying rate, sample temperature, and energy consumption. However, it did not affect the drying rate at the end of the drying. At the two-stage microwave power level, the drying time was similar to that observed in constant power level experiments. However, sample temperature and energy consumption were decreased when drying at a lower power level. Nutritional compounds were better preserved by using the highest tested power level at the two-stage level and the lowest tested one at the one-stage power level. Page’s and Fick’s models presented an excellent fit of the experimental data. Using the two-stage microwave power level at a higher initial power level (MWVD-5-1) saved energy, decreased the drying duration, and preserved the bioactive molecules in restructured chips.

Abstract The objective of this work was to evaluate biomass accumulation and photosynthesis in mangabeira, in response to water deficit and to successive soil drying and wetting cycles. Seedlings were grown in pots and subjected to the three following water regimes: soil at 35, 70, and 100% of field capacity (FC), followed by a drying-down period until photosynthesis (measured weekly) was close to zero. Then, the seedlings were rewatered until completing four drying-wetting cycles. The control treatment was a permanently well-irrigated soil. There was a decline in biomass accumulation under water deficit conditions. Photosynthesis responded to soil rewatering only at 70 and 100% FC and was null at 35% FC. The elapsed time for photosynthesis to reach a null value after rewatering increases with successive drying-wetting cycles. In soil at 100% FC, for photosynthesis to approach zero, it takes five weeks in the first and eight weeks in the last rewatering cycle. Photosynthesis improves with progressive drying-wetting cycles, particularly in soil at 100% FC. The pre-acclimation of mangabeira to drying-wetting cycles should be considered before transplanting the seedlings in the field, and pre-acclimation should be carried out initially with soil at its FC.

Abstract The objective of this work was to evaluate the use of cellulase and pectinase as pretreatments for the drying of beetroot (Beta vulgaris). The experiment consisted of slices of beetroots subjected to four different treatments before the drying procedure, as follows: no wet pretreatment; wet pretreatment without enzymes; pectinase solution pretreatment; and cellulase solution pretreatment. Treatments were compared for drying rates, color change, content of betalains, and plant tissue structure. A modified Page model was used to describe the drying process. The enzymatic pretreatments did not improve the drying kinetics, although they changed the plant tissue structure. A negative influence on the drying was observed when pectinase was used; however, no effect was observed when cellulase was used. Slices treated with cellulase remained unchanged for color. Slices treated with pectinase showed significant changes of color, in comparison with the control treatments. The enzymatic pretreatments studied did not change the betalain concentrations and showed similar drying performance in the comparison with control treatments. Cellulase pretreatment is promising because it does not change the beetroot color or the betalain concentration.

Whole and halved strawberries were dried by using three methods, which were solar tunnel drying, shade drying, and microwave drying (180W, 540W, and 900W) to determine drying characteristic and modelling. The researchers measured solar irradiation at ambient and drying air temperatures and air velocity at specific intervals in various parts of the dryer. How microwave drying (180, 540, and 900 W) affected the drying time and drying ratio of the whole and halved strawberry samples was investigated. In addition, the data on the drying process were applied to 5 different mathematical models, which were Weibull distribution, Midilli et al., Jena and Das and Aghbashlo et al. Equation Models. The researchers compared the performance levels of the models according to correlation coefficient (R2), chi-square value (x2), besides the root mean square error (RMSE) between moisture ratios that were observed and predicted. Furthermore, the Weibull Distribution and Midilli et al. models were found to reveal the ratio of drying in a satisfactory way for all the methods of drying.

Abstract The objective of this work was to adjust the coefficients of six mathematical models and to identify the one that best represents the drying of flint corn grains in a thin layer. For this purpose, a drying column was developed to obtain experimental data. Nine tests were performed for each model, using the velocities of 0.5, 1.0, and 1.5 m s-1 at 40, 50, and 60°C, respectively, for drying air. The thin-layer drying models of Lewis, Page, Thompson, Overhults, Brooker, and Midilli were tested. All adjusted models represent the phenomenon of flint corn drying at 5% probability (χ2 test). After adjusted, the models of Page, Midilli, and Overhults are the best ones for drying corn, with a coefficient of determination equal to 1.000 for all tests and errors lower than 1.0%. For the drying conditions of this work, the n parameter of the model of Page does not depend on the velocity and temperature of drying air, while the k parameter depends only on air temperature, which is confirmed by the analysis of variance. The adjusted model of Page can be used with precision for the prediction of thin-layer flint corn drying.

ABSTRACT This study aimed to fit mathematical models to whey foam drying processes in different air temperature conditions, to determine the effective diffusion coefficient and to obtain the activation energy. For foam formation, 5.0% Emustab® was added to the serum in mass and subjected to stirring in a domestic shaker for 15 min. After, it was spread onto trays to form a thin layer of about 1 cm in which the drying conditions were: 40, 45, 50, 55 and 60 °C, 5.6 m s-1 and 60%. The Logarithm and Midilli models describe the kinetics of serum foam drying; the effective diffusion coefficient increased with the elevation of drying temperature and activation energy of 50.84 kJ mol-1.

ABSTRACT Radio frequency (RF) drying is a rapid dehydration technique that reduces water activity and extends the shelf life of agricultural products. In this study, the drying characteristics of jujube during HARF and hot air (HA) were investigated, and quality analyses, such as color, vitamin C (VC) and total flavonoid content (TFC), of jujube were performed. The drying curves revealed that the drying time used to reduce the moisture content from 81.7 to 6.0% on a dry basis was 360 and 1320 min using HARF drying and hot air (HA) drying, respectively. The logarithmic model was the best to describe the HARF drying process with R 2, RMSE and SSE values of 0.998, 0.00508 and 0.000306, respectively. Quality analysis demonstrated significant differences in color, VC content and total flavonoid content between the HARF and HA treatments during the drying process and storage periods (P > 0.5), and the HARF-dried jujube product performed much better than that dried by HA. Compared with HA drying, HARF drying showed a shorter drying time, higher drying efficiency and better product quality, indicating that HARF drying was a more promising drying method for jujube with acceptable product quality.

Abstract Drying is a fundamental process in the food industry, especially for highly perishable foods, such as fruits and vegetables, because they tend to have short durability post-harvest, resulting in economic and environmental losses. The Refractance Window (RW) is a suitable technique for fruits and vegetables as it maintains the nutritional quality of the raw material in the dry product. Although RW is more energy-efficient than hot air-based techniques, the equipment traditionally consumes electricity, largely obtained from fossil fuels, emitting polluting gases. As a solution to this problem, hybridization of the heating system can be adopted in the drying process. Hybridization is when two or more heat transfer techniques are used in food dehydration. Renewable alternatives, such as solar energy, represents a clean and abundant energy source. The integration of these technologies (RW with solar energy) represents a technological improvement for the food industry, especially regarding environmental concerns. The present study analyzed the current progress in the integration of renewable energies into traditional RW for the drying of fruits and vegetables, as well as highlighted the existing knowledge gaps.

ABSTRACT The HEC-RAS software reaches its 6.0.0 version in May of 2021, introducing new computational tools to its users. Among these new tools, HEC-RAS is capable of simulating spatially varied rain and evaporation data by grid, constant values or table format. A 2D Sinos river model was created with the intent of testing mainly these two new tools. The Sinos river is located in the state of Rio Grande do Sul, Brazil. The model was calibrated and validated before being used. This article focus mainly in describing floodplain drying, those in which are used for agricultural purpose.

The drying experiments were performed at different temperatures of the drying air (40, 50, and 60°C) and air velocity of 2.5 and 3.5 m/s. Six thin-layer drying models were evaluated and fitted to the experimental moisture data. The fit quality of the models was evaluated using the determination coefficient, chi-square, and root mean square error. Among the selected models, the Midilli et al. model was found to be the best model for describing the drying behaviour of olive pomace. Charcoal is used as a domestic fuel for cooking and heating in many developing countries. It is an important green source for making barbecue, which is obtained from agricultural waste. Due to less CO2 emission, it reduces health risk and deforestation. The coal briquette carbonisation production process consists of a carbonisation stage and a forming stage. During the forming stage, the raw material is mixed with a suitable binder. The final stage of the charcoal process after formation is drying. In this study, the drying parameters of charcoal briquettes made from the olive pomace-making process were evaluated. Three different temperatures and velocities were selected for the drying applications. The low temperature drying process was performed at 60, 50, and 40°C with air velocities of 3 and 2.5. The results were in the range of 3 to 8 hours of drying time. The drying data were applied to six different mathematical models, namely 1Diffusion Approach, 2Henderson and Pabis, 3Two term exponential, 4Midilli et al., 5Page, and 6Wang and Singh Equation Models. The performances of these models were compared according to the coefficient of determination (R2), standard error of estimate (SEE), and residual sum of squares (RSS) between the observed and predicted moisture ratios. The Midilli et al. Diffusion Approach, and Page models described the drying curve satisfactorily in all drying methods.

O processo de secagem por atomização ou spray-drying é uma das operações mais frequentes para a obtenção de extratos secos a partir de plantas medicinais. No entanto, durante o processo de preparação desses insumos farmacêuticos ativos (IFA) de origem vegetal, uma série de fatores podem afetar a qualidade desses produtos intermediários. Por meio de levantamento bibliográfico científico e da legislação brasileira sobre medicamentos fitoterápicos, vivências do grupo em pesquisa e desenvolvimento (P&D) da Fiocruz e da realização de Brainstorming entre os integrantes da equipe, foi elaborado um diagrama de causa e efeito (Diagrama de Ishikawa). Tal pesquisa teve o objetivo de levantar pontos críticos no processo de produção desses IFA de origem vegetal, apontando aspectos do processo de spray-drying de ordem teórica e prática que poderiam afetar a qualidade do produto fitoterápico. Com base nas informações mencionadas no diagrama e na discussão desses pontos acerca de cada etapa até a preparação do extrato seco, foi possível racionalizar o processo de obtenção desse intermediário, com foco em transformá-lo em produto fitoterápico.

Abstract Olive leaf is a residue in olive oil and fruits production, which is considered with bioactive potential due to the high antioxidant activity attributed mainly to the phenolic compounds. The research aimed to investigate the Brazilian olive leaf drying, and also study its influence on the bioactive potential of the leaf. The desorption isotherms of olive leaves were determined and experimental curves were fitted to GAB, BET and Peleg models. Convective drying in a fixed bed dryer was used in different conditions of air temperature (50 ºC and 70 ºC) and air speed (0.9 m s-1 and 1.5 m s-1). Drying curves were obtained for each experimental test. The bioactive potential was reflected in the determination of total phenolic content, antioxidant activity and color parameters. Among the moisture equilibrium predictions between the GAB, BET and Peleg models, the first showed a better predictable capability. The results showed that in the drying operation, the increase in air temperature and speed influenced the increase in the drying rate and the reduction of time. The values of the effective diffusivity of the olive leaves varied between 2.61 x 10- 9 m2 s-1 and 10.12 x 10-9 m2 s-1. The samples dried until 10% of moisture (wet-basis) showed a good antioxidant activity, higher than 85%, and maintenance of the phenolic compounds regarding the fresh leaves around 70%. Bleaching and yellowing of leaves after drying were observed for all studied conditions and a decrease in green color at 70 ºC and 1.5 m s-1, in this condition the L*a*b* color parameters were 35.39, -5.00 and 42.66, respectively. This study demonstrated that the proper drying condition was at 70 ºC and 1.5 m s-1 for olive leaf drying and these conditions were important to maintain the original characteristics of the leaves and to spend less time in operation. Thus, this paper describe a viable drying process to take advantage of the olive leaf for the benefit of the environment and human health.

ABSTRACT This study aimed to evaluate drying kinetics for natural and pulped coffee, using different temperatures and drying airflows. For the conduction of the experiment, coffee fruits (Coffea arabica L. cv. Topázio) were harvested manually, selecting only ripe fruits and subsequent to the hydraulic separation. For drying the coffee, use a mechanical dryer with two temperatures (40 and 45°C) and four drying air streams (24; 60; 96 and 132 m3.min-1.m-2). Twelve models for employees to describe the drying kinetics of coffees. Among the models used to describe the drying process of natural coffee and pulped coffee, according to the results of the coefficient of determination, relative mean error, standard deviation of estimates and distribution of waste distribution, proposed model for the only one that presents fit for all as conditions study. The temperature of 45 ° C and the airflows of 96 and 132 m3.min-1.m-2 provide the shortest drying times regardless of the coffee processing type.

Impact of microwave-grill-drying (MWGD) at different powers (300, 450 and 600 Watts) on functional properties of berry "Russian olive» was investigated. The effect of microwave water and oil holding capacities, gelation, foaming and emulsifying, which will provide novel and applicable knowledge for the food industry, was determined. We specifically focused the kinetics drying by increasing microwave-grill powers (300, 450W and 600W), drying time decreased from 270 to 120s. For dried Russian olive berry at each applied microwave-grill power, water holding capacity values were higher than oil holding capacity values. However, drying at 450W is the best method of retention of functional properties of fresh fruit of E. angustifolia L.

ABSTRACT This work aimed to study the immediate and latent effects of different relative humidities on the quality of dried coffee fruits, describe the drying kinetics of natural immature coffee (Coffea arabica L.), and evaluate the mathematical model that best fits the experimental drying data. The drying was carried out in a fixed layer dryer coupled to a composite air conditioning system in which the drying air was controlled with an air flow of 20 m3.min1.m−2, at a temperature of 40 °C, and at relative humidities of 10%, 17.5% and 32.5%. Manually harvested coffee fruits were used and dried to a mean water content of 0.120 dry basis (d.b). After drying, the kinetic curve and the physical and physiological properties were determined. The coffee was stored in permeable packs for 6 months. The electrical conductivity, potassium leaching, and colour analysis were performed every 2 months. For the modelling adjustment, the models were tested, and the Midilli model had the best fit with the drying kinetics of the immature coffee. No immediate damage was observed in the physical and physiological quality of the coffees, and latent damage was perceived after 120 days of storage for the natural immature coffees.

ABSTRACT: Purple-fleshed sweet potatoes are rich in phenolic compounds, such as anthocyanins, and also exhibit hypoglycemic properties. Anthocyanins are natural antioxidants with the capacity to inhibit or delay injuries caused by free radicals. Drying is one of the most commonly used vegetable preservation methods; although,it has parameters that affect the sensory and physicochemical properties of the final product. The present study assessed the impact of drying temperatures (40, 50, and 60 °C) on the purple-fleshed sweet potato. Cut, unpeeled potato slices of 4 cm in diameter and 3 mm in thickness were dried in an oven with hot air circulation. The effect of the different temperatures on the antioxidant capacity, phenolic compound content, and total and monomeric quantities of anthocyanins in purple sweet potato were measured, and a mathematical model describing the drying kinetics was determined. According to the results observed, the process at 40 °C better preserved the phenolic compounds; however, drying at 50 °C was more efficient for conserving the antioxidant capacity measured by the H + capture method performed by DDPH, and for the total and monomeric quantities of anthocyanins. The mathematical models that best described the kinetic curves were those of Henderson and Pabis, and Page.

ABSTRACT Serapias vomeracea is an economically valuable plant belonging to the Orchidaceae family; particularly, its tubers are consumed as hot drinks. Past studies on S. vomeracea have focused on volatile components only in the aerial parts of this orchid. This study is the first to investigate the volatile compounds present in S. vomeracea tubers, which have a high commercial value. Additionally, we determined the effect of harvest time and drying method on the volatile compound profile. The tubers were harvested on two different days (May 17, 2022, and June 6, 2022) and subjected to four different drying conditions (shade drying, oven drying, shade drying after boiling, and lyophilizer drying). To determine the volatile compound profile, sample extracts were prepared by solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry. Overall, 22 volatile compounds were identified: 3 esters, 3 aldehydes, 3 alcohols, 3 terpenes, 3 alkanes, 3 carboxylic acids, 1 phenol, 1 ketone, 1 lactone, and 1 furan. The results revealed that p-cresol was the main compound. During harvesting and subsequent drying, some compounds were lost, and some new compounds were formed. Moreover, harvest time had quite limited effects on volatile compounds in the lyophilizer method. Cluster analysis revealed that the combination of harvest time and drying was effective in the distribution of volatile compounds in salep powder.

ABSTRACT Analyzing the impact of harvest-time drying data is crucial for successful storage and maintaining regulatory seed quality. This study aimed to assess the performance of fixed and mobile dryers using machine learning techniques. Data were collected from convective dryers, including the total number of dryers used, drying time (in hours), moisture percentages at the product’s entrance and exit, and the humidity difference between them. The study employed the Filtered Clusterer model, which utilizes the Simple K-Means technique and the Resample filter to group data based on similarities. The findings indicated distinct differences between fixed and mobile drying systems, with well-defined variations within each system. The algorithm, combined with the applied filters, proved effective in unsupervised classification by identifying and reducing inter-cluster similarity within the fixed system, thereby creating distinct classes within the dataset. In conclusion, the algorithm successfully clustered the scattered dataset and accurately classified and minimized inter-cluster similarity within the fixed system. Conversely, the mobile system exhibited low drying efficiency.

ABSTRACT This study proposes automating an air conditioning system for drying and storing agricultural products. The main objective is to precisely control key parameters of the air, namely temperature, relative humidity, and air velocity, to optimize the drying process. The framework required for constructing and operating the automated air conditioner is explained in detail. Specifically, we describe the conditioning unit, the automation hardware, the control strategies employed to regulate temperature, relative humidity, and air velocity, and discuss the safety measures and human-machine interfaces of the system. Experimental validation of the proposed system is presented, along with results and discussions demonstrating its successful control of drying air parameters across a wide range of desired conditions.

Abstract Drying is one of the stages of coffee processing and has been considered one of the factors that impact the quality of the final drink. In this sense, the present study developed a phenomenological model for a box-type dryer implementing in C / C ++ programming language. The profile of the exhaust air temperature was obtained over the drying time. The model was verified by comparing data obtained from the literature, thus guaranteeing its functionality to make predictions about the air temperature profile in equipment used by small coffee producers, which may contribute to the increase in product quality.

Abstract Brazil nuts are often used for direct consumption or in the preparation process of water-soluble extract. After obtaining the water-soluble extract, a large amount of Brazil nut residues with good sensory characteristics are generated. Thus, this study aimed to dry Brazil nut processing residues in layers with different thicknesses in a direct solar dryer as well as by direct exposure to the sun, in order to fit different mathematical models to the experimental data of drying kinetics, and calculate the drying rates and effective diffusivity. The drying procedures began at 9 a.m. on a concrete base, for samples dried by direct exposure to the sun, and in a solar dryer constructed with expanded polystyrene foam zinc plated and a glass cover. The mass loss of the samples was monitored by weighing at regular times until the hygroscopic equilibrium was obtained. The direct solar dryer had temperatures about 80% higher than those recorded in the open environmental air temperature. Drying rates were higher in dehydrations performed in the solar dryer compared to the drying by exposure to the sun. The Midilli model was selected as the most adequate for predicting the drying of the samples under all experimental conditions, showing coefficients of determination above 0.99. The effective diffusion coefficients of moisture were higher in samples dehydrated in the solar dryer when compared to those dried by exposure to the sun. Regarding the research conducted under the experimental conditions of this study, the performance of the solar dryer to dry Brazil nut processing residues was satisfactory.

Abstract Apple (Malus Demestica cv. Cortland) is a perishable fruit due to its high moisture content. In this study, apple sticks were dried to increase their shelf life. Osmotic dehydration was used as pretreatment followed by microwave-assisted hot air drying (MAHD) at different temperatures (45 ºC, 55 ºC, 65 ºC) and microwave power densities (0, 0.5, 1 W/g). Optimum process parameters were estimated by the central composite design of response surface methodology (RSM). The results showed that the temperature and power density had a significant effect on response variables. Optimum conditions of moisture content (9.54%), time (100 minutes) and change in color (7.54) were found at 65 ºC and 1 W/g microwave power density (MWPD). Then the samples dried at optimum conditions were stored at ambient temperature and analyzed for color, moisture content, texture and total fungal count at regular intervals for 75 days. The results showed a non-significant change in color and fungal counts from 10.45 to 10.73 and from 0.45 to 0.69 log cfu/g respectively, and a significant decrease in moisture content from 10.11% to 5.69% was observed from 0 to 75 days. While increasing firmness resulted in increased force and energy to the breaking point and micrographs of electron microscope showed shrinkage in cell structure along with storage. The brittleness of apple sticks increased significantly during storage but remained acceptable till the end of 75 storage days.

Abstract Kuini powders were obtained through spray-drying, freeze-drying, vacuum oven drying and convection oven drying. Colour, water activity (Aw), moisture content, hygroscopicity, wettability, flowability, degree of caking, water solubility index (WSI), total colour change, total phenolic content and total carotenoid content of Kuini powders were determined and compared. Convection oven drying resulted in the highest yield (46.97%), moisture content (4.91%), Aw (0.55) and WSI (74.33%) among all the drying methods. However, convection oven-dried Kuini powder had the lowest hygroscopicity and wettability, which were 18.66% and 12.04 s, respectively. Spray drying resulted in poor hygroscopicity (22.41%), degree of caking (22.16%), wettability (275s), WSI (45.67%) and higher colour change (59.81). Least total colour change (19.05) and higher yellowness (57.31) were observed in freeze-drying. In addition, freeze-dried Kuini powder had the highest total phenolic content (24.76 mg/100 g) and total carotenoid content (1.61 mg/100 g). Drying temperature had a negative and significant correlation with the retention of color pigments and antioxidant content. The physicochemical properties and antioxidant content of freeze-dried Kuini powder were preferred over spray-dried, vacuum oven-dried and convection oven-dried powders. Hence, freeze-drying offers potential application in the food products.

Abstract The objective of this work was to develop a drying process using the foam-layer method to obtain the powder from butiá (Butia spp.) pulp, as well as to characterize this powder according to its yield and physicochemical and technological characteristics. The foam was optimized for density and stability by varying whipping times and albumin and xanthan gum concentrations. Foam drying was optimized for vitamin C retention and yield using different foam thicknesses and drying temperatures. The optimized foam showed a density of 0.25 g cm-3 and a high stability, being suitable for subsequent drying. The lowest foam thickness (0.50 cm) and the highest drying temperature (80°C) resulted in the highest retention of vitamin C, whereas the increase in drying temperature improved yield. The butiá pulp powder obtained under the optimized condition presented an acid pH of 3.25, a low humidity of 7.97%, a water activity of 0.206, a water retention capacity of 4.90 g H2O per gram of powder, a solubility of 74.40%, a soluble solids content of 61°Brix, and a predominantly yellow color. The foam-layer drying method can be used to obtain butiá pulp powder.

ABSTRACT The search for the reduction of production costs and for the diversification of the commercialization of agricultural products is necessary when looking to ensure autonomy and increase income for farmers. The use of solar dryers for the dry fruits production provides an excellent alternative for consideration. However, in order to introduce this technology, one must understand the drying kinetics for a given product. This paper’s purpose was to study the intermittent drying kinetics of banana in a hybrid dryer. The drying was performed in a hybrid dryer composed of a solar collector (photothermal energy), a drying chamber containing Banana-Prata cut into cylindrical and disc shapes and a power-driven exhaust system. The process occurred during four sequential days, totaling 78 h of operation and 12 h of intermittence. The effective drying period took 39 h, with a temperature and relative humidity inside the drying chamber of 43.4 °C and 45.3%, respectively, and an air speed of 1.0 m.s-1. In the first few hours of drying, a sharp decrease in the moisture content was verified. During this period, the maximum and minimum drying temperatures were approximately 42 and 28 °C, respectively. A higher reduction in the moisture content of the disc samples was observed when compared to the cylindrical shape. After the intermittence period, a peak of moisture ratio was observed, followed by a marked loss of water in the fruit in both formats. The results have shown that the Page model is the one that better applies to the experimental data for the intermittent solar drying of banana in both shapes.

In order to control the fission, boric acid is added to the water of primary circuit inside a Pressurized Water Reactor (PWR). After used, this solution is treated in evaporator to reduce its volume, generating the evaporator concentrate (EC). This concentrate should be solidify for transported and storage. Cementation is one of available process to incorporate the concentrate. However, when the evaporator concentrate is cemented there is an increase in the volume of the final product. It is proposed to use an additional process, drying prior be to the cementation. This process is applicable to further reduce the waste volume to be solidificated reducing the number of waste packages, consequently decreasing the storage area and all related risks. Two equipment, lab oven and spray dryer were studied to treat the evaporator concentrate. The dried EC was characterized, and the density, the particle size and the surface area were determined. After drying the evaporator concentrates solution, there was more than 80% weight reduction and initially, the dried product of the spray dryer showed better conditions to be incorporated in cementitious matrix.

ABSTRACT: The objective of this research was to determine the proximate composition and kinetics drying of sweet pine nuts compared to typical pine nuts of Araucaria angustifolia. This study is based on the proximate components, color, and duration of pine nuts drying of both types, and the influence of temperature and cutting geometry on the dehydration process. Sweet pine nuts had lower calorific value and carbohydrate content, but higher lipid, dietary fiber, protein, and ash contents when compared to typical pine nuts. Color of sweet pine nuts is light pink whereas the typical pine nut is yellowish-white. Sweet pine nuts were also softer. Drying kinetics of the seeds fit well into the logistic and Thompson models. To accelerate drying rates, we recommend slicing pine nuts into thin cross-sections and drying them at temperatures of 60 °C for typical pine nuts and 70 °C for sweet pine nuts.

ABSTRACT Mechanical properties of agricultural products are essential for a proper project design or processing equipment dimensioning, as well as for establishment of parameters on the supported load. An experiment was set up in a completely randomized design, with five treatments (continuous and intermittent drying under 4, 8, 12, and 16 h of rest period) and four replications, to evaluate the effect of intermittent drying. Corn kernels of the cultivar Cargo TL were harvested with a moisture content of 25.37% wb and submitted to drying in an experimental fixed bed dryer set to a temperature of 100 °C and an airflow of 1.5 m3 min-1 m-2. Drying was performed until the kernels reached a moisture content of 14±0.3% wb. The process was interrupted in the intermittent drying with a moisture content of 18±0.2% wb and continued after rest period until the final moisture content was reached. The analysis consisted of 10 kernels randomly selected per replication and submitted to the uniaxial compression test after determining their dimensions. Rupture force, maximum deformation, energy to rupture point, modulus of toughness, hardness, and drying rate during drying were evaluated. The increase in rest period promoted a linear increase in the rupture force and hardness. Modulus of toughness, energy to rupture point, and maximum deformation were not affected by the rest period. The increase in rest period contributed to increasing the drying rate.

The generation of dust due to the transport and handling of iron ore is a prominent environmental problem today. The reduction of emission levels has been the focus of many companies in the mineral sector, which implement solutions such as the use of suppressive products and the enclosure of transfer points. Dust emission is potentiated by local atmospheric conditions, which cause the evaporation of surface moisture from the wet ore, breaking the liquid bridges that hold the particles together. In addition to mass loss, the moisture gradient between the dried surface and the lower layers initiates and maintains moisture transport by capillarity and diffusion for surface evaporation. To define the sinter feed drying dynamics, an open section drying tunnel with a weighing system and humidity sensor was used to replicate three different atmospheric conditions (1,5m.s-1 e 23°C; 3,0m.s-1 e 26°C; 4,5m.s-1 e 29°C). The experimental curves were fitted with Page's model and showed an initial period of constant rate followed by a period of decreasing rate The drying time for the mildest condition was 90h and the minimum time was 30h for the maximum temperature and speed adopted. The maximum and minimum drying rates obtained were 2,6g.m.-2. h-1 0,3g.m-2. h-1. The results of the study can be used as a basis for strategies to reduce dust emissions, resulting in an improvement in the quality of life of the community impacted by the environmental problem. [ABSTRACT FROM AUTHOR]

ABSTRACT Studies of post-harvest storage and drying in macauba fruit (Acrocomia aculeata (Jacq.) Lodd. Mart) are still in the early stages. The aim of this work was to investigate the effect of drying on the quality of macauba kernel oil during storage. Drying was carried out under three different air temperatures: 40°C, 50°C and 60°C. Four replications were used for each temperature. After drying, the kernels were stored for 0, 60, 120, 240 and 360 days, and the following physico-chemical analyses were carried out for each period: kernel oil content, acidity index, oxidative stability, water activity and oil colour. An increase in storage time resulted in an increase in the acidity index and a reduction in the oxidative stability of the oil in all treatments. The mean value for water activity in the oil ranged from 0.56 to 0.68. The mean values of the L* and b* coordinates did not differ from the control, except for the storage times of 0 and 60 days. There was a difference in the a* coordinate between the drying processes when compared to the control. No significant differences were seen for oil content. It was concluded that drying can be efficient tool in controlling the quality of kernel oil during storage.

ABSTRACT: The influence of drying methods (oven drying at 50 °C, and freeze drying) on the centesimal composition, functional characteristics and rheological properties of mucilage obtained from chia seed and psyllium husk were investigated. Results showed that high temperature of oven drying reduced fiber content, solubility, emulsion activity and emulsion stability of mucilage. All samples showed pseudo plastic behavior, with the best result produced by Heschel-Bulkley and Power Law models of chia and psyllium mucilage, respectively. These results will be helpful in selecting suitable drying methods depending on the functional and rheological properties desired of the chia and psyllium mucilage in a food product.

Abstract Laurus nobilis constitutes one of the usually studied Mediterranean trees due to its therapeutic effects, nutritional properties, and ornamental use. In the current investigation, a comparative study was conducted between two types of drying methods, a microwave-assisted drying (MWD) (from 180 to 900 W) and a conventional method (open-air and oven-drying using temperatures from 40 °C to 120 °C). Drying kinetics were carried out as a function of moisture content according to time. Total Phenolic Content (TPC) as well as reducing power of obtained products were determined. Kinetic results showed that the time required for dried bay leaves became shorter as temperature and microwave power increased; drying with the microwave was much more efficient than conventional methods (open-air and oven-drying). Antioxidants of the Laurus nobilis leaves were better conserved using open-air and microwave drying. Our results underlined a significant correlation between TPC and reducing power. Microwave drying using 300 W during 130 s was the most efficient combination that provided dried bay leaves with the highest content of phenolic compounds and antioxidant activity.

ABSTRACT New, efficient, low-cost techniques for image processing and alternative machine learning for seed processing are of academic and industrial interest. This study aims to identify fissures in bark and peeled rice seeds using X-ray and RGB image processing techniques and machine learning. Samples of three batches of rice seeds were used: a batch of seeds not subjected to drying (peeled seed), and the other two comprised of dried seeds, one containing seeds with husk and another containing huskless seeds; each sample comprised 100 seeds. Images in X-ray and RGB formats were provided in the sequence processed in ImageJ software and introduced in the machine learning software, where they were pre-processed using the appropriate filters and then classified by the J48 and linear discriminant analysis (LDA) classifiers. X-ray images obtained using differentiated equipment allow the identification of cracks in rice seeds using image processing techniques and the LDA classifier. Capturing images using RGB is a viable alternative. Using filters, either individually or in combination, may constitute an adequate alternative for rice seed classification.

ABSTRACT The importance of the functional properties of edible mushrooms as a food product has been increasing and several studies have emerged to address this issue. However, the application of a conservation process is required since this is a product with a high moisture level. The aim of this study was to investigate the drying kinetics of shiitake Lentinula edodes mushrooms by means of the construction of drying curves, the mathematical modeling of the drying curves, and correlating the data obtained with the β-glucan content in order to observe the influence of temperature on its content. The drying temperatures of 35 ºC, 45 ºC and 55 ºC were applied to construct the drying curves and the β-glucan contents of the samples were quantified. Mathematical modeling was performed in order to identify the best model for the representation of the product moisture loss during the drying period. The equilibrium humidity values were 0.346% for 35 ºC, 0.892% for 45 ºC and 0.875% for 55 ºC, and the β-glucan contents showed no significant difference for the three temperatures analyzed, as confirmed by the Tukey test. Of the eight mathematical models fitted to the drying curves, the Page and the Midilli models provided the best results. Therefore, based on the findings, 55 °C appears to be the optimum temperature for the Shiitake mushroom drying process in the studied conditions, as it provides the shortest drying time and the β-glucan content is maintained.

A goiaba (psidium guajava) é uma fonte de vitamina C, licopeno, β-caroteno e fenóis, os quais têm propriedades antioxidantes. Porém, devido a sua alta perecibilidade uma grande parcela da goiaba colhida é perdida antes de chegar ao consumidor. Por isso, alguns métodos de preservação precisam ser utilizados, e o método de desidratação por foam mat drying possui grande potencial para preservação desta fruta. O processo de secagem por foam mat drying para a polpa de goiaba foi avaliado variando diferentes concentrações de lecitina de soja e carboximetilcelulose como agentes estabilizadores de espuma na temperatura de secagem de 80 °C. As análises de caracterização assim como os parâmetros de cor foram avaliados na polpa de goiaba desidratada em todos os ensaios de secagem, no intuito de verificar a melhor condição de secagem. A análise estatística indicou diferença significativa (p < 0,05) para o conteúdo de vitamina C, fenóis totais e capacidade antioxidante pela influência da concentração de carboximetilceululose e lecitina de soja. No entanto, houve aumento significativo para a capacidade antioxidante e fenóis totais na polpa de goiaba desidratada em todas as condições avaliadas em comparação com a polpa in natura. O estudo concluiu que a condição de secagem com a concentração de 0,15 g de Carboximetilcelulose e 0,15 g de Lecitina de Soja / 100 g apresentou menor tempo de secagem e concomitantemente, maiores valores para fenóis totais, capacidade antioxidante e melhor retenção da vitamina C em comparação com as outras condições de secagem avaliadas.