Dados do Trabalho

Título

THICKNESS AND WETTABILITY OF CASSAVA STARCH FILMS WITH RED ONION SKIN EXTRACT RICH IN FLAVONOIDS

Introdução

Conventional packaging poses a significant environmental issue, underscoring the urgent need for sustainable alternatives. In this context, biodegradable packaging is becoming indispensable. Additionally, there is growing interest in intelligent packaging capable of monitoring food quality. Flavonoids extracted from red onion skins are promising for this purpose due to their pH-responsive color-changing ability. This study aimed to develop films from cassava starch, a biodegradable polymer enriched with red onion skin extract (ROSE).

Material e Métodos

To prepare the ROSE, dried and ground skins were mixed with 70% ethanol (v/v, in distilled water) and heated in a water bath at 60 ºC for 3 h. The extract was then filtered, the solvent was evaporated under vacuum at 60 ºC, and the extract was lyophilized. The films were produced by casting, using a filmogenic solution prepared with 4% (w/v) cassava starch in distilled water and 30% glycerin (w/w, relative to starch), heated to 90 ºC for 30 min. After cooling to 40 ºC, ROSE was added at concentrations of 0, 2 and 4% (w/w) and homogenized in an ultra-turrax at 11,000 rpm for 5 min. The polymeric solutions (20 g, individually) were dried at 35 ºC for 24 h. The ROSE was characterized by its total flavonoid content, while the films were evaluated for thickness and contact wettability.

Resultados e Discussão

The ROSE proved to be rich in flavonoids, with a total content of 455.6 mg quercetin equivalents/g. The thickness of the films was 0.100, 0.106, and 0.131 mm for films with 0, 2, and 4% ROSE, respectively. The contact angles were 81.3° for films with 0% ROSE, 75.5° for 2% ROSE, and 76.1° for 4% ROSE.

Conclusão

All films exhibited hydrophilic characteristics, with contact angles measured at less than 90º. Incorporating ROSE into the films increased thickness due to the higher amount of solids and decreased hydrophobicity due to the presence of free OH groups in ROSE. Although other parameters still need to be evaluated, the films have the potential for application as active packaging. They are recommended for food products with low water activity or applied with no direct contact with the food due to their hydrophilic nature.