This study employed response surface methodology to optimize the spray-drying conditions for a microencapsulated oregano extract (Origanum vulgare L.) using a maltodextrin-gum Arabic wall-material system. Feed flow rates of 0.5, 0.6, and 0.7 L h-1 and inlet air temperatures of 130, 140, and 150 °C were evaluated. The oregano leaves were dried, ground, and extracted by maceration with 90% (v/v) ethanol at a 1:10 mass-to-solvent ratio at 60 °C for 24 h under agitation. Process yield, encapsulation efficiency, and moisture content were evaluated. The optimal conditions within the experimental domain were a feed flow rate of 0.5 L h-1 and an inlet air temperature of 150 °C. Independent validation under these conditions resulted in a process yield of 94.97%, encapsulation efficiency of 94.06%, and moisture content of 3.15%, with relative prediction errors of 0.13, 0.60, and 0.73%, respectively. The resulting spray-dried microencapsulated oregano extract showed 92.0% solubility, a bulk density of 0.24 g mL-1, a tapped density of 0.48 g mL-1, a Carr index of 50%, a Hausner ratio of 2.00, an angle of repose of 31.58°, and hygroscopicity of 21.49 g 100 g-1. Its ferric reducing antioxidant power was 402 µmol Fe2+/g sample, and its total polyphenol content was 0.15 mg g-1. Overall, the optimized process produced a spray-dried microencapsulated oregano extract with high process yield and encapsulation efficiency and measurable antioxidant-related activity, supporting its further evaluation as a functional food ingredient. Keywords: microencapsulation; oregano extract; spray drying; antioxidant capacity.
O estudo avaliou os efeitos da substituição do fubá de milho por farinha de melão (Cucumis melo L.) como fonte de carboidrato na alimentação de alevinos de tambaqui (Colossoma macropomum). Foram utilizados 120 alevinos, com peso inicial médio de 3,01 ± 0,13 g, distribuídos em quatro dietas com 0 (controle), 33, 66 e 100% de substituição, em triplicata (10 peixes por tanque), durante 45 dias. Ao final, foram analisados o desempenho de crescimento, os metabólitos e a atividade de enzimas digestivas. Os dados foram submetidos à análise de variância (ANOVA), seguida do teste de Tukey (P<0,05) e análise de regressão. Os maiores valores de ganho de peso e de taxa de crescimento específico, e a menor conversão alimentar, foram observados nos tratamentos com 0 e 33% de substituição. Níveis mais elevados de farinha de melão aumentaram o colesterol plasmático e reduziram os níveis de aminoácidos livres e de glicogênio hepático. Além disso, dietas com substituição de 66 a 100% elevaram a atividade da enzima aspartato aminotransferase hepática. Conclui-se que a farinha de melão pode substituir o fubá de milho em até 33% nas dietas de alevinos de tambaqui, sem comprometer o desempenho produtivo e a eficiência alimentar, o que a apresenta como uma fonte alternativa de carboidratos. Palavras-chave: alimento alternativo; Colossoma macropomum; Cucumis melo L. Evaluation of melon flour in replacing cornmeal in tambaqui: performance and metabolism ABSTRACT: This study evaluated the effects of replacing cornmeal with melon flour (Cucumis melo L.) as a carbohydrate source in the diet of tambaqui (Colossoma macropomum) fingerlings. One hundred and twenty fingerlings, with an average initial weight of 3.01 ± 0.13 g, were used, distributed into four diets containing 0% (control), 33%, 66%, and 100% substitution, in triplicate (10 fish per tank), for 45 days. At the end, growth performance, metabolites, and digestive enzyme activity were analyzed. Data were subjected to analysis of variance (ANOVA), followed by Tukey's test (P<0.05) and regression analysis. The best results for weight gain, daily gain, and feed conversion were observed in the treatments with 0% and 33% substitution. Higher levels of melon flour increased plasma cholesterol and reduced free amino acids and hepatic glycogen. Furthermore, diets with 66 to 100% substitution increased hepatic aspartate aminotransferase enzyme activity. It is concluded that melon flour can replace cornmeal by up to 33% in the diet of tambaqui fingerlings, without compromising growth performance and feed efficiency, representing an alternative source of carbohydrates. Keywords: alternative food; Colossoma macropomum; Cucumis melo L.
Water quality monitoring is essential for understanding and assessing physical, chemical, and microbiological characteristics, while accounting for spatial and temporal variations driven by climate, soil, and land use and land cover. Given this context, the study aimed to evaluate whether surface water quality is affected by land use and land cover in the Renato and Caiabi river basins, located in the southern Amazon region. The Water Quality Index (WQI) and Trophic State Index (TSI) were determined at eight sampling points on the Renato River and five on the Caiabi River across four seasonal transitions (wet, wet-to-dry, dry, and dry-to-wet), following methodologies from Standard Methods for the Examination of Water and Wastewater. The Renato River presented a water quality compliance index exceeding 90%, while the Caiabi River recorded 90.45%, considering Class 2 rivers. For both rivers, parameters such as temperature, acidic pH, low electrical conductivity, turbidity, nitrogen, and chlorophyll a indicated an absence of effluent discharge. Dissolved oxygen, biochemical oxygen demand, total organic carbon, thermotolerant coliforms, and total suspended and dissolved solids exhibited greater seasonal variability but remained within regulatory limits. Both the Renato and Caiabi rivers displayed a "good" WQI and an oligotrophic TSI, indicating low eutrophication potential and an absence of adverse impacts on water usage, despite significant land use and land cover changes within the basins. Keywords: water quality index; LULC; agricultural watersheds; Cerrado-Amazon transition.
Este trabalho apresenta o desenvolvimento e a avaliação preliminar de um sistema embarcado para análise colorimétrica da maturação de frutos de açaí (Euterpe oleracea Mart.). O protótipo integra o sensor TCS34725, o microcontrolador ESP32, processamento local, um modelo de aprendizado de máquina, comunicação Bluetooth, um aplicativo Android e um encapsulamento produzido por impressão 3D. O desenvolvimento foi realizado de forma iterativa, incluindo ajustes no isolamento óptico, no processamento de sinais e na seleção dos atributos de entrada. Uma base inicial composta por 300 registros, distribuídos entre os estágios Verde, Intermediário e Maduro, foi utilizada em uma configuração exploratória de três classes, cuja validação interna apresentou acurácia de 85,7%, com maior dificuldade na discriminação do estágio Intermediário. Em uma etapa posterior, restrita aos estágios Verde e Maduro e utilizando atributos colorimétricos refinados, a validação interna apresentou acurácia de 100%. Os resultados indicam a viabilidade do sistema como plataforma embarcada para aquisição, processamento e classificação colorimétrica, embora sejam necessários estudos com frutos independentes, diferentes lotes, condições experimentais e uma referência independente para avaliar sua capacidade de generalização. Palavras-chave: Euterpe oleracea; TCS34725; ESP32; aprendizado de máquina; sensores ópticos. Development and preliminary evaluation of an embedded system for colorimetric analysis of açaí ripeness ABSTRACT: This study presents the development and preliminary evaluation of an embedded system for colorimetric assessment of açaí fruit (Euterpe oleracea Mart.) ripening. The prototype integrates a TCS34725 color sensor, an ESP32 microcontroller, local processing, a machine-learning model, Bluetooth communication, an Android application, and a 3D-printed enclosure. The system was developed iteratively, including improvements in optical isolation, signal processing, and input-feature selection. An initial dataset containing 300 records distributed among Green, Intermediate, and Ripe stages was used in an exploratory three-class configuration, which achieved 85.7% accuracy in internal validation, with the Intermediate stage showing the greatest classification difficulty. In a subsequent stage restricted to Green and Ripe fruits and using refined colorimetric features, internal validation achieved 100% accuracy. The results indicate the feasibility of the system as an embedded platform for colorimetric acquisition, processing, and classification, although further studies involving independent fruits, different batches, experimental conditions, and an independent reference are required to assess its generalization capability. Keywords: Euterpe oleracea; TCS34725; ESP32; machine learning; optical sensors.
Este trabalho apresenta um estudo geofísico de parte da orla fluvial sujeita à erosão, com o objetivo primordial de avaliar seu uso na deteção de áreas degradadas pela erosão em estágio crítico, antes de seu possível desmoronamento. Esta área está situada ao longo de 600 m à margem do rio Guamá, entre a ponte do rio Tucunduva e o Porto de Canoagem, dentro do campus da Universidade Federal do Pará (UFPA), na cidade de Belém no Estado do Pará (Brasil). Conta, em alguns trechos, com diferentes tipos de contenção da erosão, como muros de concreto e sacos de cimento. A investigação combinou sondagem a análises granulométricas e imageamento elétrico com o método eletrorresistividade ao longo de quatro trechos do perfil da orla, comparando medições nos períodos de maré baixa e maré alta. O método geofísico de eletrorresistividade foi utilizado para investigar a movimentação do terreno. As medidas foram realizadas durante a maré baixa e a maré alta, com o objetivo de mapear os caminhos preferenciais subsuperficiais de entrada de água trazida pela maré alta e, por meio deles, o trabalho erosivo. Os resultados demonstram que o método pode ser uma ferramenta auxiliar na possível previsão de locais onde a queda erosiva do terreno, provocada por ela, está prestes a ocorrer. Palavras-chave: estudo geofísico; erosão de rios; análise granulométrica; geotécnica. Fluvial erosion of the Guamá River using electrical resistivity ABSTRACT: This study presents a geophysical analysis of an erosion-prone section of the riverbank, primarily aiming to evaluate the method's utility in detecting areas suffering from critical erosion before potential collapse. The study area spans a 600-meter stretch along the Guamá River - between the Tucunduva River bridge and the Canoagem Port - within the Federal University of Pará (UFPA) campus in Belém, Pará, Brazil. Certain sections feature various erosion control measures, including concrete walls and cement bags. The investigation combined borehole data and grain-size analysis with electrical resistivity imaging across four segments of the riverbank profile, comparing measurements taken during low and high tides. Electrical resistivity geophysics was employed to investigate ground movement. Measurements were conducted during both low and high tides to map subsurface preferential pathways for tidal water ingress and the associated erosive activity. The results demonstrate that this method can serve as a valuable tool for predicting locations where erosion-induced ground collapse is imminent. Keywords: geophysical study; river erosion; grain-size analysis; geotechnics.
