RESUMO A aeração é realizada por meio da insuflação do ar externo para dentro do silo, tendo como objetivo manter a temperatura da massa de grãos armazenados em níveis seguros. No presente estudo foi estimada a eficiência energética da aeração de grãos de girassol armazenados, assim como proposto e testado um modelo de estimativa da eficiência energética da aeração, utilizando diferentes algoritmos no aprendizado de máquinas supervisionado e não supervisionado. O objetivo no trabalho foi desenvolver uma aplicação Web a partir da mineração e modelagem dos dados com o aprendizado de máquinas. O banco de dados foi composto pelas informações da temperatura média do nível dos sensores, temperatura média do silo, temperatura ambiente externa, ocorrência de aeração, se houve resfriamento, aquecimento e aquecimento direto durante aeração, e a eficiência energética do processo de aeração. O modelo de estimativa da eficiência energética do processo de aeração demonstrou-se eficiente, identificando que durante a aeração de grãos de girassol armazenados a eficiência energética foi de 97,78%. Dentre os algoritmos classificadores testados na Máquina de Vetores de Suporte (SVM-Poly) apresentou as melhores métricas e indicadores, sendo recomendado para implementação em redes de desenvolvimento de sistemas capaz de predizer o status da aeração de grãos armazenados. silo seguros sensores externa resfriamento demonstrouse demonstrou eficiente 9778 97 78 97,78% SVMPoly SVM Poly (SVM-Poly indicadores 977 9 7 97,78 97,7 97,

ABSTRACT Aeration is carried out by blowing external air into the silo, with the aim to keep the temperature in the mass of stored grains at safe levels. In the present study, the energy efficiency of aeration of stored sunflower grains was estimated, and a model was proposed and tested to estimate the energy efficiency of aeration, using different algorithms in supervised and unsupervised machine learning. The objective of the work was to develop a Web application based on data mining and modeling with machine learning. The database was composed of information on the average temperature at the height of the sensors, average temperature of the silo, external ambient temperature, occurrence of aeration, if there was cooling, heating and direct heating during aeration, and the energy efficiency of the aeration process. The model for estimating the energy efficiency of the aeration process proved to be efficient, identifying that the energy efficiency was 97.78% during the aeration of stored sunflower grains. Among the classifier algorithms tested, Support Vector Machine (SVM-Poly) showed the best metrics and indicators, hence being recommended for implementation in system development networks capable of predicting the aeration status of stored grains. silo levels study estimated learning sensors cooling efficient 9778 97 78 97.78 SVMPoly SVM Poly (SVM-Poly indicators 977 9 7 97.7 97.

RESUMO O uso de sensores de CO2 tem sido reportado como uma medida eficaz na detecção precoce de sinais de deterioração, permitindo uma boa acurácia na tomada de decisão sobre a qualidade de grãos armazenados. Neste estudo objetivou-se quantificar os níveis de CO2 produzidos por grãos de milho armazenados em temperatura ambiente em silo protótipo, com teores de água iniciais de 14, 16 e 18% b.u., bem como avaliar a qualidade do produto ao longo do tempo e a quebra técnica. Foram realizadas análises de teor de água, cinzas, proteínas, lipídeos, Hue Angle (cor), germinação e condutividade elétrica. No interior dos silos foi monitorada a quantidade de CO2, umidade relativa do ar e temperatura a cada uma hora. As avaliações de qualidade dos grãos ocorreram em quatro tempos de armazenamento (0, 30, 60 e 90 dias). Foi usado o delineamento inteiramente casualizado, em esquema fatorial 3 × 4 e seis repetições. Os grãos mais úmidos apresentaram maior quebra técnica e perdas associadas a emissões de CO2. Os teores de água, proteína, lipídeos, germinação, massa específica aparente, L* e croma reduziram ao longo do tempo, enquanto que a condutividade elétrica aumentou, resultando em maior danificação das membranas e perda de qualidade dos grãos de milho. O monitoramento do CO2 na massa de grãos é uma boa ferramenta para avaliar a qualidade dos grãos, e maior teor de umidade inicial causou maior nível de emissão de CO2 e redução na qualidade dos grãos de milho. CO deterioração objetivouse objetivou se protótipo 14 1 18 bu b u b.u. cinzas proteínas lipídeos cor, cor , (cor) hora 0, 0 (0 30 6 9 dias. dias . dias) casualizado repetições proteína aparente L aumentou b.u (cor (

ABSTRACT The use of CO2 sensors has been reported as an effective tool in the early detection of signs of deterioration, allowing good accuracy in decision-making about the quality of stored grains. The objective of this study was to quantify the CO2 levels produced by maize grains stored at ambient temperature in a prototype silo, with initial moisture contents of 14, 16 and 18% w.b., and to evaluate the quality of the product over time and the technical breakage. Analyses of moisture content, ash, proteins, lipids, Hue Angle (color), germination and electrical conductivity were performed. Inside the silos, the amount of CO2, relative air humidity and temperature were monitored every hour. Grain quality evaluations were carried out at four storage times (0, 30, 60 and 90 days). A completely randomized design in a 3 × 4 factorial scheme with six replicates was used. Grains with higher moisture contents showed higher technical breakage and losses associated with CO2 emissions. Moisture content, protein, lipids, germination, bulk density, lightness and chroma decreased over time, while the electrical conductivity increased, resulting in greater damage to membranes and loss of quality of maize grains. Monitoring of CO2 in the grain mass is a good tool to assess the quality of grain, and higher initial moisture content caused greater level of CO2 emission and reduction in quality of maize grains. CO deterioration decisionmaking decision making silo 14 1 18 wb w b w.b. ash proteins lipids color, color , (color) performed silos hour 0, 0 (0 30 6 9 days. days . days) used emissions protein density increased w.b (color (

RESUMO Grãos são materiais higroscópicos, e em seu armazenamento estão sujeitos às trocas de vapor de água de acordo com a temperatura e umidade relativa do ar, sendo importante o monitoramento desses fatores. Os sensores digitais de temperatura e umidade relativa do ar surgem como alternativa para monitoramento da temperatura da massa de grãos no interior de silos, apresentando simplicidade de instalação e utilização. Sensores digitais apresentam destacada precisão nas medições de temperatura. O objetivo deste estudo foi verificar a eficiência e aplicabilidade de sensores de umidade relativa do ar intergranular atrelados a sensores digitais de temperatura no sistema de termometria de silos armazenando grãos de soja. Duas amostragens de grãos de soja no terço superior, médio e inferior do silo foram analisadas para a temperatura da massa de grãos, umidade relativa do ar intergranular, teor de água de equilíbrio estimado conforme dados coletados e teor de água dos grãos amostrados. Realizou-se a comparação do teor de água obtido a partir das medições dos sensores usando a equação do equilíbrio higroscópico e pela determinação através do método da estufa. O teor de água de equilíbrio estimado pelos dados fornecidos pelos sensores não diferenciou pelo teste de Tukey (p ≤ 0.05) do teor de água determinado pela estufa. Os sensores digitais de temperatura e umidade relativa do ar demonstraram-se eficientes, visto que contribuem para estimativa do teor de água de equilíbrio com precisão satisfatória. higroscópicos fatores utilização superior amostrados Realizouse Realizou se estufa p 0.05 005 0 05 demonstraramse demonstraram eficientes satisfatória 0.0 00 0.

ABSTRACT Grains are hygroscopic materials and, during storage, they are subject to exchanging moisture with the environment according to temperature and relative air humidity, making it important to monitor these factors. Digital temperature and relative air humidity sensors appear as an alternative for monitoring the moisture of grain mass inside silos; they are simple to install and use. Digital sensors present outstanding precision in temperature measurements. The objective in this study was to assess the efficiency and applicability of intergranular relative air humidity sensors linked to digital temperature sensors in the thermometry system of silos storing soybeans. Two samples of soybeans were analyzed in the upper, middle and lower thirds of the silo, for grain mass temperature, intergranular relative air humidity, estimated equilibrium moisture content according to collected data, and moisture content of the sampled grains. Moisture contents obtained from sensor measurements using the hygroscopic equilibrium equation and determined using the oven method were compared. The equilibrium moisture content estimated by the data provided by the sensors did not differ by the Tukey test (p ≤ 0.05) from the moisture content determined by the oven method. Digital temperature and relative air humidity sensors have proven to be efficient, as they contribute to estimating the equilibrium moisture content with satisfactory precision. storage factors use upper silo grains compared p 0.05 005 0 05 efficient 0.0 00 0.

RESUMO Neste estudo objetivou-se descrever o estágio de fluxo de secagem constante, bem como obter o teor de água crítico durante a secagem convectiva da pasta de folhas de jambu trituradas em diferentes condições e caracterizar as propriedades físicas do material após a secagem. A secagem foi realizada em estufa de circulação de ar com velocidade de 1,0 m s-1 nas temperaturas de 60, 70 e 80 ºC e espessuras da camada de 0,005 e 0,01 m. Para a determinação do estágio de taxa constante, foram calculados os fluxos de massa e a taxa de secagem. Os polinômios segmentados foram utilizados para estimar o teor de água crítico. Nas condições analisadas houve um comportamento típico de secagem, demonstrando a existência de um expressivo período de taxa constante de secagem para a pasta de folhas de jambu trituradas. Os teores de água críticos em função da espessura e temperatura não apresentaram uma tendência. O material apresentou características físicas favoráveis, como alta solubilidade e coesividade, escoamento livre e boa molhabilidade, características que agregam valor à matéria-prima e para a disponibilização de um novo produto ao mercado em condição de acondicionamento. objetivouse objetivou se 10 1 0 1, s1 s s- 60 7 8 0005 005 0,00 001 01 0,0 tendência favoráveis coesividade molhabilidade matériaprima matéria prima acondicionamento 6 000 00 0,

ABSTRACT The objective of this study was to describe the constant drying flux stage, as well as obtaining the critical moisture content during the convective drying of jambu leaf paste crushed under different conditions and characterizing the physical properties of the material after drying. Drying was carried out in an air circulation oven at a speed of 1.0 m s-1 and temperatures of 60, 70 and 80 ºC and layer thicknesses of 0.005 and 0.01 m. To determine the constant rate stage, the mass fluxes and the drying rate were calculated. Segmented polynomials were used to estimate the critical moisture content. Under the analyzed conditions, a typical drying behavior was found, demonstrating the existence of a significant period of constant drying rate for the mass of ground jambu leaves. Critical moisture content as a function of thickness and temperature did not show a trend. The material showed favorable physical characteristics, such as high solubility and cohesiveness, free flow, and good wettability, characteristics that add value to the raw material and for the availability of a new product to the market in the condition of packaging. stage 10 1 0 1. s1 s s- 60 7 8 0005 005 0.00 001 01 0.0 calculated found leaves trend cohesiveness flow wettability packaging 6 000 00 0.

RESUMO: A secagem de produtos agroindustriais é utilizada visando preservar as qualidades sensoriais e nutricionais, bem como reduzir a atividade biológica que impede a deterioração e a perda do valor comercial. Assim, objetivou-se neste trabalho estudar a modelagem matemática da secagem da casca de goiaba para obtenção de farinha, bem como determinar o coeficiente de difusão efetivo, a energia de ativação e as propriedades termodinâmicas nas temperaturas de secagem de 45, 55, 65 e 75 °C. O experimento foi realizado no Instituto Federal Goiano - Campus Rio Verde, e as goiabas foram adquiridas no comércio local do município de Rio Verde, GO, no estádio de maturação comercial. Dentre os modelos analisados, Midilli foi selecionado para representar a cinética de secagem da casca de goiaba. O coeficiente de difusão efetivo aumentou com a elevação da temperatura e a energia de ativação para a difusão líquida na secagem foi de 37,207 kJ mol-1. A entalpia e a entropia diminuíram com a elevação da temperatura de secagem, enquanto a energia livre de Gibbs aumentou com o incremento da temperatura de secagem. RESUMO nutricionais comercial Assim objetivouse objetivou se farinha 45 55 6 7 C °C Verde GO analisados 37207 37 207 37,20 mol1. mol1 mol 1. 1 mol-1 4 5 3720 3 20 37,2 mol- 372 2 37,

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 activity value 45 55 6 7 C °C Goiás maturity models phenomenon 37207kJ kJ 37 207kJ mol1. mol1 mol 1. 1 mol-1 4 5 3 mol-

ABSTRACT This study aimed to obtain the sorption isotherms of grain sorghum flour, fit mathematical models to experimental data, and recommend safe water levels for preserving the material at different temperatures. Sorghum grains with an initial moisture content of 34% dry basis (db) were subjected to drying at a temperature of 60 °C, reaching moisture contents ranging from 32.20 to 9.8% db. Water activity was obtained using Hygropalm Aw1 equipment placed inside a BOD chamber at temperatures of 10, 20, 30, and 40 °C. The experimental data were fitted to mathematical models frequently used to predict the isotherms of plant products. The modified Oswin model presented the best fit to estimate the sorption isotherms of sorghum flour. Safe moisture content limits for storing sorghum flour are 18.45, 17.3, 16.08, and 15.2% db for temperatures of 10, 20, 30, and 40 °C, respectively. The isosteric heat for the range of equilibrium moisture contents from 9.80 to 32.20% db varied from 2779.49 to 2498.46 kJ kg−1. 34 (db 6 C °C 3220 32 20 32.2 98 9 8 9.8 Aw 10 30 4 products 1845 18 45 18.45 173 17 3 17.3 1608 16 08 16.08 152 15 2 15.2 respectively 980 80 277949 2779 49 2779.4 249846 2498 46 2498.4 kg1 kg 1 kg−1 322 32. 9. 184 18.4 17. 160 0 16.0 15. 27794 277 2779. 24984 249 2498. kg− 18. 16. 27 24

Abstract Thus, the objective of this work was to evaluate the performance of industrial drying and the quality of soybean grains using a direct-fire furnace automatically fed by wood chips. To represent the grains before drying, four samples were collected together with the sampling of the loads in the trucks carried out to classify the product in the storage unit. At drying, performance evaluations and specific energy consumption were carried out. The grains were evaluated for moisture content, germination, electrical conductivity, apparent specific mass, color, acidity index, and PAHs. Drying showed an average efficiency of 75.50%. The average chip consumption was 0.4403 kg of chip/kg of evaporated water. The specific energy consumption was 8,099.50 kJ/kg of evaporated water. The grains showed differences after drying in the characteristics of germination, electrical conductivity, and chroma. Six PAHs were detected in the samples before drying: (B(a)A, Chr, 5 MC, B(j)F, Dib(ai)P, and IcdP). After drying, in addition to the PAHs obtained before drying, five more were detected (B(b)F, B(k)F, B(a)P, Dib(al)P, and Dib(ah)A). Mean PAH concentrations were higher than the maximum values allowed by European Union legislation. Thus directfire direct fire chips unit content germination conductivity mass color index 7550 75 50 75.50% 04403 0 4403 0.440 chipkg water 809950 8 099 8,099.5 kJkg kJ chroma BaA, BaA B A, A (B(a)A Chr MC BjF, BjF j F, F B(j)F DibaiP, DibaiP Dib ai P, P Dib(ai)P IcdP. IcdP . IcdP) BbF, BbF b (B(b)F BkF, BkF k B(k)F BaP, BaP B(a)P DibalP, DibalP al Dib(al)P DibahA. DibahA ah Dib(ah)A) legislation 755 7 75.50 0440 440 0.44 80995 09 8,099. Dib(ah)A 75.5 044 44 0.4 8099 8,099 75. 04 4 0. 809 8,09 80 8,0 8,

ABSTRACT Sorghum ( Sorghum bicolor L. Moench) is a crop of paramount importance for Brazil, used in human and animal food. Considering the reduced number of studies on the influence of using a densimetric table in seed processing and its respective reprocessing to the equipment, this study aimed to evaluate the physiological quality of processed sorghum seeds reprocessed in a densimetric table and stored for three months. The treatments consisted of four collection points in the terminal part of the densimetric table, representing the processing material: upper part (P1), upper middle part (P2), middle part (P3), and lower part (D). Subsequently, the samples that were reprocessed in the table came from P3 and were divided into the upper part, which was followed to bagging (P3R1), and the lower part (P3R2), which followed for disposal, totaling six treatments. Storage was performed in a refrigerated environment, using a completely randomized design, with the means being compared by Tukey’s test at 5%. We concluded that the reprocessing of sorghum seeds in the densimetric table can improve the physical quality of a lot due to its standardization at the end of the stages, contributing to the improvement of the physiological quality and use of the material that would be discarded. The equipment performance allows the removal of seed fractions with lower apparent specific mass and promotes positive stratifications in the physiological quality of sorghum seed lots. L Moench Brazil food months P1, P1 P , (P1) P2, P2 (P2) P3, (P3) D. D . (D) Subsequently P3R1, P3R1 PR R (P3R1) P3R2, P3R2 (P3R2) disposal environment design Tukeys Tukey s 5 5% stages discarded lots (P1 (P2 (P3 (D P3R (P3R1 (P3R2 (P (P3R

RESUMO Chicória é um vegetal tradicionalmente consumido como salada crua ou cozida. É uma fonte de importantes compostos nutricionais e um dos procedimentos para sua industrialização é a secagem, que aumenta a vida útil, preserva seus nutrientes e reduz as perdas por microrganismos. Esta pesquisa avaliou a cinética de secagem de folhas de chicória em diferentes temperaturas e ajustou os dados experimentais de acordo com modelos matemáticos. O delineamento experimental foi inteiramente casualizado, em triplicata, onde cada unidade amostral era uma bandeja de alumínio perfurada, contendo cerca de 100 g de folhas frescas. As folhas de chicória foram secas em estufa, a 50, 60, 70 e 80°C. Os modelos matemáticos foram ajustados de acordo com os dados experimentais e, a partir deles, a análise de regressão não-linear foi realizada pelos métodos de Gauss-Newton e Quasi-Newton. Em todas as condições, os modelos matemáticos que melhor se ajustaram à cinética de secagem das folhas de chicória foram o Midilli, o Logarítmico e o Valcam. O modelo logarítmico, nessas condições de secagem, pode ser descrito com precisão como adequado para prever e simular a cinética de secagem das folhas de chicória, pois apresentou melhores resultados nos parâmetros estatísticos avaliados. cozida útil microrganismos casualizado triplicata perfurada 10 frescas estufa 50 60 7 80C C 80 80°C deles nãolinear não linear GaussNewton Gauss Newton QuasiNewton. QuasiNewton Quasi Newton. Quasi-Newton Midilli Valcam logarítmico avaliados 1 5 6 8

ABSTRACT Endive is a vegetable traditionally eaten as a raw or cooked salad. It is a source of important nutritional compounds and one of the procedures for its industrialization is drying, which increases its shelf life, preserves the nutrients and reduces losses due to microorganisms. This research evaluated the drying kinetic of endive leaves at different temperatures and adjusted the experimental data according to mathematical models. The experimental design was completely randomized in triplicate, with each sample unit being a perforated aluminum tray containing about 100 g fresh leaves. The endive leaves were dried in an oven at 50, 60, 70 and 80°C. The mathematical models were adjusted according to the experimental data; non-linear regression analysis was performed by Gauss-Newton and Quasi-Newton methods. In all conditions, the mathematical models that best fitted the drying kinetics of the endive leaves were Midilli, Logarithmic and Valcam. The Logarithmic model, under these drying conditions, can be accurately described as suitable for predicting and simulating the drying kinetic of endive leaves, as it showed the best results in the statistical parameters evaluated. salad life microorganisms triplicate 10 50 60 7 80C C 80 80°C nonlinear non linear GaussNewton Gauss Newton QuasiNewton Quasi methods conditions Midilli Valcam model 1 5 6 8

Abstract The objective of this study was to evaluate the influence of drying treatment on the characteristics physical, chemical, technological properties and bioactive of turmeric flour. The flour was obtained from the drying of rhizomes in a forced air circulation oven at temperatures of 45, 55, 65 and 75 °C. The analyzes performed were: pH, instrumental color, microstructure, granulometry, water and oil absorption indices, water solubility indices, and antioxidant activity. The characteristics of the flours significantly affected were moisture, protein, lipid and ash contents. The antioxidant capacity with the DPPH radical, for flour at the drying temperature of 45 °C, presented the highest value 36.55 Mmol Trolox g-1, and 7686.32 Mmol FeSO4 g-1 the FRAP radical at 65 °C.The phenolic content varied according to the solvent applied to obtain the extract, the mean values of total phenolic compounds for each temperature were: 0.419, 0.332, 0.316, 0.283 mg GAEa 100 g-1for temperatures 45, 55, 65 and 75°C respectively. Water solubility index (WSI) and oil absorption index ranged from 12.45 g g-1 to 11.78 g g-1 and from 2.54 g g-1 to 2.49 g g-1, respectively, for temperatures of 45 °C and 75 °C. The results of the present study indicated that temperature influences the physicochemical and technological properties of turmeric flour.

Abstract The Croton urucurana Baill species is known in Brazil as “sangra d’água” and is popular due to its medicinal properties. For better processing of herbal medicines, it is essential that efficient drying and storage techniques are developed and that compounds are preserved. Therefore, this study aimed to select models through multivariate cluster analysis applying Akaike (AIC) and Bayesian information criteria (BIC) to describe Croton urucurana leaves drying kinetics at different temperatures (40-70 °C). The initial moisture content in Croton urucurana leaves was 1.791, 1.841, 2.196 and 2.144 kg water kg dry matter-1, and 8.25, 7.75, 4.25 and 2 hours were required to reach hygroscopic equilibrium, with a final moisture content of 0.134, 0.105, 0.065 and 0.0601 kg water kg dry matter-1, at 40, 50, 60 and 70 °C, respectively. The models with the greatest similarity to the experimental data were Diffusion Approximation; Cavalcanti Mata; Two-term; Two-term Exponential; Modified Henderson & Pabis; Logarithmic; Midilli; Page and Verma. The multivariate cluster technique associated with AIC and BIC criteria during model selection is a great applicability tool to help decision-making when evaluating the drying plant leaves. The Cavalcanti Mata mathematical model was selected to represent the drying kinetics.

Abstract Araticum (Annona crassiflora) fruits have relevant characteristics for industrialization, a characteristic aroma and a slightly acidic flavor, with relevant amounts of vitamins A, C, B1 and B2. The objective of this study was to fit different mathematical models to the experimental data, evaluate the effective diffusion coefficient and determine the activation energy for the araticum epicarp subjected to different drying conditions. The epicarps of araticum fruits were dried at temperatures of 40, 50, 60 and 70 °C. Midilli, Logarithmic and Two Terms models can be used to represent the drying of araticum epicarp, and the Two Terms model was selected according to the Akaike Information Criterion (AIC) and Schwarz’s Bayesian Information Criterion (BIC). The linear model satisfactorily represented the effective diffusion coefficient as a function of drying temperature. In the evaluation of enthalpy, entropy and Gibbs free energy, both enthalpy and entropy tend to decrease when temperature increases. The higher the temperature used for drying of araticum epicarp, the lower the value of diffusivity, i.e., the lower the resistance to water removal.

Abstract The objective of this study was to evaluate the drying system using a dryer with furnace automatically fed with eucalyptus chips and another dryer manually fed with eucalyptus firewood, as well as assessing the quality of corn grains. Harvest was mechanically performed and the grains were transported by trucks to the storage unit for drying. Corn grain drying was conducted in mixed-flow dryers with a nominal capacity of 100 tons per hour. For air heating, two direct-fired furnaces were used, one automatically fed with eucalyptus chips and the other manually fed with firewood. Corn grains were evaluated for moisture content, apparent specific mass, thousand-grain weight, polycyclic aromatic hydrocarbons (PAHs), electrical conductivity and color. Drying corn grains with direct fire using firewood or chips as fuel causes contamination by PAHs. In general, the use of firewood or chips did not influence the quality of thousand-grain weight, apparent specific mass and color, while the use of chips increased electrical conductivity. It is essential that research advances in this subject, prioritizing the contamination of food, with proven carcinogenic activity, which should be treated as a high risk to public health.

Abstract The drying is one of the stages of processing Brazil nuts, being an important stage due to the high moisture content and water activity of the product. This study aimed to adjust mathematical models to the drying kinetics data of Brazil nuts, calculating the effective diffusion coefficient and obtaining activation energy for the drying process. Brazil nuts were collected in amazon region, and then the product was homogenized for processing. The nuts were subjected to drying in a forced ventilation oven at temperatures of 40, 50, 60, 70 and 80 °C in 4 replicates, each one consisting of approximately 200 g of samples in aluminum containers. Mathematical models were adjusted to the experimental data of the moisture content ratio. Thompson, Midilli, Logarithmic and Two Terms models are suitable for estimating the drying of Brazil nuts. The Two Terms model was selected to represent the drying phenomenon for presenting better results in the analyzed parameters. The effective diffusion coefficient increased with increasing temperature and the activation energy for the liquid diffusion in the drying was 35.69 kJ mol-1.

ABSTRACT. Drying is an important step in the post-harvest processes as a way of product conservation and quality preservation. In this context, this study aimed to evaluate the effect of continuous and intermittent drying of maize grains with different rest periods on the integrity of their micro- and macroscopic structures. Maize grains were harvested with a moisture content of 0.3399 ± 0.001 dry basis (db) and subjected to continuous and intermittent drying with 4, 8, 12, and 16 hours of rest period. An experimental fixed-bed dryer, with controlled drying air conditions at a temperature of 100 °C and air flow of 1.5 m3 min.−1 m−2 (12 m3 min.−1 m−3), was used. Continuous drying was completed with a moisture content of 0.1628 ± 0.0003 db, whereas intermittent drying was interrupted with 0.2195 ± 0.0002 db and resumed after rest. The drying rate, integrity through grain images, the conformation of particles through scanning electron microscopy, and cell membrane integrity were evaluated. The drying rate increased with an increase in the rest period, the increase in rest period reduced the intensity of cracks, and the reduction in rest period led to higher dispersion and reduction in the size of starch granules and lower integrity of cell membranes.