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Microencapsulação de KNO₃ com amido de milho nativo e modificado por atomização
(Universidade Federal de São Carlos, 2025-06-03) Jesus, Isabella Mikules de; Santos, Rodrigo Ragazzi dos; https://lattes.cnpq.br/0570139033358988; https://orcid.org/0009-0000-0814-7259; Faez, Roselena; https://lattes.cnpq.br/0654750186618555; https://orcid.org/0000-0001-9501-0794; https://lattes.cnpq.br/6114263827034052; https://orcid.org/0009-0003-5615-9547
The continuous growth of the global population has demanded increased food production, leading to the excessive use of fertilizers and worsening environmental damage. A promising way to mitigate these impacts is the use of enhanced efficiency fertilizers (EEFs), which consist of nutrients encapsulated in polymeric, ceramic, or composite matrices that control the release of nutrients into the soil. In this study, corn starch (modified or not) was evaluated as a matrix for encapsulating nutrients (K and N in the form of KNO₃) using the spray drying technique. The variation in the equimolar ratio of the encapsulated salts was analyzed, and in the case of amphoteric starch (with both positive and negative charges), its net charge and the degree of substitution of the cationic (3-chloro-2-hydroxypropyltrimethylammonium chloride) and anionic (phosphate) functional groups were determined. Before spray drying, citric acid was directly added to the starch/KNO₃ solution, allowing for the formation of microcapsules with and without crosslinking. This approach aimed to promote in situ crosslinking of the biopolymers, with the goal of delaying nutrient release and enhancing the structural resistance of the microcapsules. Additionally, swelling tests were conducted to assess the effects of crosslinking on the physicochemical properties of the materials. The results indicated that crosslinked corn starch showed greater resistance to solubility and better control of nutrient release, proving more effective in simulated agricultural applications. In contrast, amphoteric starch was less efficient due to its high solubility in water, which compromised its controlled release capacity. Besides, the study proposes a pedagogical approach for high school education, based on the theme “The Chemistry of Fertilizers: Environmental Impacts and Polymer-Based Solutions,” using the STS (Science, Technology, and Society) perspective as a didactic resource.
Avaliação do impacto da amostragem, proporção massa/solvente e equipamento de extração na análise de pesticidas em alimentos
(Universidade Federal de São Carlos, 2025-06-03) José, Wesley Felipe de Paula; Fadini, Pedro Sérgio; lattes.cnpq.br/3255060531838427; https://lattes.cnpq.br/6896958965365140
This study aimed to investigate the applicability of miniaturization of conventional analytical methods for the analysis of pesticide residues in foods. With the growing demand for faster, more cost-effective, and environmentally sustainable analytical methods, there is a need to improve the procedures used for pesticide residue analysis. In classical methods employed by the agrochemical industry and private laboratories, the use of advanced instrumental techniques for separation, detection, and quantification of analytes contrasts with the tedious, time consuming and manual methods used for sample preparation, which can delay and increase the cost of the entire analytical process. Therefore, this research project investigated how different variables employed during the extraction of pesticide residues in foods can influence the levels of residues found in these samples, with the aim of automating the analytical methods. For this purpose, results of six active ingredients (mefentrifluconazole, pyraclostrobin, fluxapyroxad, teflubenzuron, boscalid, and dimoxystrobin) were evaluated in four different matrices (tomato, citrus, cotton, and rice). A full factorial design (23) was utilized, considering the extraction techniques (Ultra Turrax and vortex mixer), sample mass (0.20 g and 2.50 g), and mass/sample volume ratio (1:8 and 1:20). The results obtained indicated that, even with small sample masses, comparable standard deviations were achieved compared to conventional methods. Furthermore, the mass/sample volume ratio showed low significance in the variation of results for the tested levels. Although some variables, such as sample mass and equipment, presented significant effects, these effects were within the expected variability for pesticide analyses. Additional experiments were performed to validate the applicability of miniaturization and automation of the analytical methods.