Química Nova
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Item Functional and technological properties of coffee mucilage (Coffea arabica) and its application in edible films(Sociedade Brasileira de Química, 2023-05-17) Machado, Daiane Bernardi; Oliveira, Rafael Augustus deBrazil is the largest coffee producer in the world, and together with the millions of tons produced, millions of tons of residues are also generated. The generated residues are a source of environmental contamination depending on the chosen processing route. One of the main applications of food industry waste is in the production of raw materials to produce edible films and coatings. Coffee mucilage is a pectin-rich liquid residue from the coffee sector that can be used in the production of value-added products. Given this, the objective of this work was to characterize and evaluate the potential of functional and technological properties of coffee mucilage and your applicability in the production of edible films. The filmogenic mixture was obtained by casting from 10% (w/v) lyophilized coffee mucilage and solvent (water). The films produced from the coffee mucilage presented good homogeneity, continuity (absence of ruptures or fragile regions), flexibility, ease of detachment of the support and handling, without the need to add adjuvant to its formation. In addition, they presented uniformity in thickness, high light barrier and medium water vapor barrier. Thus, it can be concluded that mucilage is a potential product to be used in the cosmetic, pharmaceutical and food industries.Item Café com quimioterapia: uma aplicação do planejamento fatorial fracionário 2|5-1(Sociedade Brasileira de Química, 2023-03-03) Silva, Kaique Carvalho da; Caldeira, Gabriel Rocha Figueira; Nogueira, Kenya Gomes; Canela, Maria Cristina; Filgueiras, Paulo Roberto; Souza, Murilo de OliveiraChemometrics is a subfield of chemistry that emerged from advances in analytical instrumentation and computing. When seeking to solve chemical problems that depend on many concomitants experimental variables, chemometrics can be employed in order to extract as much information as possible in the least possible number of experiments. In addition, it is possible to evaluate the important effects and interactions among the variables to understand the processes being monitored in each system. In this sense, this article aimed to develop a didactic experiment of caffeine extraction using an espresso machine, applying the 25-1 fractional factorial design. The variables studied were temperature (75 and 78 °C), pressure (2 and 15 bar), granulation (bean and ground), type of coffee (special and traditional) and period of the day (morning and afternoon) to obtain maximum extraction of caffeine. The coffee extracts obtained were analyzed using UV-Vis molecular absorption spectrophotometry. The developed experiment showed the potential to spread the application of chemometrics in the academic environment and to facilitate the teaching of fractional factorial design.Item Experimento com abacate, borra de café, licuri e leite de coco para extração de óleo, produção de biodiesel e análise espectral(Sociedade Brasileira de Química, 2018) Cunha, Silvio; Rodrigues, Marina Costa; Mattos, Rosiene Reis; Teixeira, Leonardo Sena Gomes; Santos, Airam Oliveira; Santos, Elaine V.; Souza, Rauan S.; Andrade, Givaldo dos Santos; Paula, Rodrigo De; Jesus, Djane S. deAn undergraduate organic chemistry experiment for oil extraction and biodiesel production using alternative biomass was developed, whereby oils of avocado, coconut and spent coffee grounds were obtained and submitted to transesterification reaction with CH3OH under NaOH catalysis. Avocado and coffee oils were obtained by typical extraction and coconut oil was obtained through water evaporation of coconut milk in a domestic microwave oven. The commercial oil of licuri (Syagrus coronate), a Brazilian native biomass, was also converted to biodiesel. All four oils and four biodiesels were characterized by 1H-NMR and FTIR, and a comparative study of these spectra reveled that FTIR analyses alone provides enough information to discriminate between oil and biodiesel and confirm transesterification reaction. Besides, the unsaturation degree of all oils was determined by 1H-NMR. A mechanistic proposal concerning the role of NaOH catalysis is presented, excluding the sodium methoxide formation.Item Kinetic parameters study for the slow pyrolysis of coffee residues based on thermogravimetric analysis(Sociedade Brasileira de Química, 2020) Tibola, Fernando L.; Oliveira, Tiago J. P. de; Cerqueira, Daniel A.; Ataíde, Carlos H.; Cardoso, Cássia R.Thermal decomposition of coffee husks was investigated by thermogravimetric analyses. The proximate, ultimate and composition analyses were performed. Thermogravimetric tests were realized, the material was heated to 1173 K using five heating rates: 5, 10, 15, 20, 25 K min-1. The kinetic parameters were estimated using the methods of Kissinger-Akahira-Sunose and Friedman, the distributed activation energy model and the independent parallel reactions model. The isoconversional models of Kissinger-Akahira-Sunose and Friedman showed the dependence between determined values of activation energy and mass conversion, the activation energy values varied from 1437.39 to 199.22 kJ mol-1 for Kissinger-Akahira-Sunose and from 127.81 to 230.35 kJ mol-1 for Friedman model. The values of activation energy were determined for Miura-Maki method; varying from 137.39 to 199.22 kJ mol-1. The model of parallel and independent reactions showed the presence of six different reactions (with activation energy values varying from 42.0 to 214.2 kJ mol-1) occurring during coffee husks pyrolysis, indicating a complex reaction. Currently, works regarding the determination of kinetic parameters for coffee husks pyrolysis are not common. The present work is the first report using the model of parallel and independent reactions to estimate kinetic parameters for pyrolysis of coffee husks, a residue widely generated worldwide.