Filmes de acetato de celulose incorporados com compostos antociânicos do extrato das flores de Clitoria ternatea

Abstract

The flower of Clitoria ternatea is rich in bioactive compounds, mainly non-anthocyanin phenolics and anthocyanin phenolics. The objective of this study was to evaluate the flowers of Clitoria ternatea cultivated in the South Region of Rio Grande do Sul, to extract the anthocyanin compounds using an environmentally friendly extraction method, to apply them in cellulose acetate films and to investigate the potential for application of the extract and the films in the food sector. For the optimization of the extraction, the variables time, temperature and volume of extracting solution (acidified water at 1%) were evaluated through a 23 factorial design, with central and axial points, on the total anthocyanin content. The extract obtained in the optimal extraction condition was evaluated for chemical composition, non-anthocyanin and anthocyanin phenolic content, reducing capacity, antioxidant activity, in vivo toxicity and activity against gram-positive and gram-negative food pathogens. The cellulose acetate films were produced by the casting technique incorporated with the extract of the flowers of Clitoria ternatea, as well as with the lyophilized flowers, in different concentrations, with the purpose of being an indicator of color change, against the change of pHs . The optimal extraction condition was 22.5 mL, 16 min of reaction at 45 ºC. The total monomeric anthocyanin contents in the liquid extract were between 450.29 and 554.63 mg/100 g of dry flower. The lyophilized extract was characterized by presenting: reducing capacity of 806.92 mg GAE/100 g, high antioxidant potential, low in vivo toxicity and promising results in relation to minimum inhibitory concentration and minimum bactericidal concentration, against food pathogens. In this, thirteen anthocyanins and nine non-anthocyanic phenolic compounds were quantified by UHPLC/MS, which may be associated with the observed effects. Films obtained with cellulose acetate (20% and 30% lyophilized extract; 20% and 30% lyophilized flower) did not change color at different pHs. However, a color change occurred in the extract, in the lyophilized flower and in the films when exposed to the culture of gram-negative bacterium (S. Typhimurium and E. coli). The results suggest a high potential of the extract and the films for future studies of application in active food packaging, especially as a marker of microbiological contamination by gram-negative bacterium.