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Authors
Abstract(s)
Packaging is a very important tool to prevent food waste and ensure the product desired quality along shelf life. Beyond protecting foodstuff and helping to store it in hygienic conditions, packaging can also be helpful in indicating the overall condition of the contained food. These systems that monitor/communicate food quality and safety are known as smart/intelligent packaging and are increasingly used in food industry. However, a large amount of packaging is derived from synthetic polymers and represents a major obstacle to
the sustainable development of a country, as it causes several negative impacts on nature for being nonbiodegradable. In this context, biodegradable packaging that could also permanently indicate the quality status of a product and share this information with the consumer is a challenger innovation path in food science with great potential to be absorbed in the industry. A possible way to detect food deterioration is through pH changes, which can be caused by various factors as microbial spoilage or oxidation mechanisms, among others. Through the addition of compounds that undergo easily detectable coloration changes
with pH variation, as anthocyanins, biodegradable smart films can be developed, which was the main goal of this project. To obtain the edible films, cassava starch was used together with glycerol, an important plasticizer, and anthocyanin-rich extract obtained from P. spinosa epicarp was also added to act as a pH indicator. The extract, obtained under previously optimized conditions, was tested for its chromatographic and bioactive profile. The most abundant anthocyanin compounds were cyanidin-3-O-rutinoside ([M+H]+ at m/z 595) and peonidin- 3-O-rutinoside ([M+H]+ at m/z 609), presenting a total anthocyanin content of 8.05±0.07
mg/g of extract. The extract also showed great antimicrobial activity, mainly against Salmonella enterica, with a MIC of 2.5 mg/mL, and against Escherichia coli, Staphylococcus aureus, and Aspergillus fumigatus with a MIC of 5 mg/mL. In addition, it showed a strong antioxidant activity against lipid peroxidation (TBARS assay), with an EC50 value thirteen times lower than that presented by the positive control, Trolox (10.4 ± 0.5 and
139 ± 5 μg/mL, respectively). These results support to the potential use of the extract in smart films.
For the films formulation based on cassava starch and glycerol dissolved in water, five studies were selected from the literature. The formulations were reproduced to define the ideal conditions. Two good formulations were achieved: with 0.5 g or 0.8 g of glycerol, in 100 g of water, 3 g of cassava starch, and 1 g of anthocyanins. For control samples, anthocyanin-rich extracts were not added. By testing different formulations, it was possible: to save energy, by choosing the lower temperature tested (70 °C) for gelation process; to save the degassing process by not forming bubbles at this temperature; and to verify the
influence of each condition in the film formation process. The gelation temperature and relative humidity control during the drying process had the most important influence on the success of film manufacturing. Subsequently, the visual effects observed by varying the proportions of the ingredients were supported by FTIR and SEM evaluation. Overall, it was possible to conclude that the formulations presented good homogeneity and cohesion. The increase in glycerol from 16.6 to 26.6 g/100g of starch affected some bands in the FTIR spectra, also being observed by lower surface resistance by SEM. As for the addition of anthocyanins, this factor did not cause a major impact on the FTIR spectra and, despite resulting in rougher surfaces evaluated by SEM, the extract is applicable to films. Furthermore, when tested in different pH solutions, the colour of the films was effectively changed, thus reinforcing the applicability of the anthocyanin extract in films based on cassava starch and glycerol, with potential application for monitoring pH changes
in food products.
Description
Mestrado de dupla diplomação com a Université Libre de Tunis
Keywords
Food waste Hygienic conditions