RESUMO
The kinetic release of phenolic compounds from biodegradable films with Clitoria ternatea flower extract (ECT) in different food-simulant fluids and compostability were evaluated for the first time. This work aimed to incorporate ECT in starch-PVA-based film formulations, and the antioxidant capacity, total phenolic compounds, opacity, color, mechanical properties, compostability, and polyphenol release in different fluid simulants were determined. The results obtained showed that antioxidant activity and the total phenolic compounds were ECT dose dependent. Due to its antioxidant properties, ECT interfered with the film's composting process, reaching an average weight loss of 70 %. Additionally, the addition of ECT interfered with the mechanical properties, reducing the tensile strength, probably due to the plasticizer effect. The type of simulating fluid influenced the release of polyphenols from the films, and the presence of water favored the release because it hydrated and swelled the starch-PVA matrix, facilitating diffusion. The classic zero- and first-order models were the most effective in describing the release kinetics of polyphenols from the films. The results of this study demonstrate that the antioxidant potential and the release of polyphenols from starch-PVA-based films in different simulated fluids allow their application in active packaging, making them a sustainable alternative for food preservation.
Assuntos
Antioxidantes , Clitoria , Antioxidantes/farmacologia , Amido , Fenóis , Polifenóis , Flores , Embalagem de AlimentosRESUMO
The open burning of municipal solid waste (MSW) -frequently observed in developing countries- emits harmful pollutants, including fine particulate matter (PM2.5) and black carbon (BC), and deteriorates the air quality in urban areas. This work reports on PM2.5 and BC measurements (fixed and mobile) conducted in a residential neighborhood on the outskirts of a Brazilian city (Londrina), complemented by a public opinion survey to understand the open burning in the context of waste management. Mean (± standard deviation) BC concentration (1.48 ± 1.40 µg m-3) at the fixed sites of the neighborhood was lower than downtown, while PM2.5 (9.68 ± 8.40 µg m-3) concentration was higher. The mobile monitoring showed higher mean PM2.5 concentrations but lower BC/PM2.5 ratios than downtown, with sharp and fast spikes (up to 317.87 and 565.21 µg m-3 for BC and PM2.5, respectively). The large spatial heterogeneity of particulate concentrations was associated with the occurrence of MSW burning events. Our observations were verified by the survey respondents who identified poor waste management practices: garbage in streets, waste burning, and illegal dump sites. Even though the area has a municipal waste collection service, the majority of the respondents (87%) had seen waste burning close to their homes on a weekly basis, and think that people burn waste out of habit (54%) and because they are not patient to wait for the collection services (67%). To combat this illegal practice, we suggest raising the public awareness through campaigns at local level, adopting education initiatives and economic incentives for correct waste segregation, and enforcing regular inspection of burning events by the authorities. Our research method proved to be a time- and cost-effective approach for mapping particulate concentrations and for identifying undesirable waste practices, and could be effectively applied to other global cities.
Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Brasil , Cidades , Monitoramento Ambiental , Humanos , Material Particulado/análise , Resíduos SólidosRESUMO
One of the main analytical variable to indicate the evolution and the phases of the composting process is temperature, whose constant monitoring is fundamental for decision making. However, studies usually perform collection of temperature data with a daily frequency due to the operational difficulty in obtaining this information from manually collected samples. Thus, the aim of this study was to determine the ideal frequency of temperature data collection in composting layers. Eight composting layers containing tree prunings + domestic organic residues were installed and four temperature sensors were installed in each layer. The temperature data were collected and recorded from minute to minute by means of a datalogger developed with an Arduino board during 70 days of composting. Thus, the collected temperatures were used as a pilot sample, and therefore the ideal temperature collection rate was estimated for different estimation error limits. No significant difference was found between the different collection times according to the Kruskal-Wallis test at a significance level of 5%. Therefore, the ideal collection frequency can be determined from the error limit of temperature estimation that is acceptable to the researcher.