Filme biopolimérico utilizando extrato de própolis marrom como agente ativo

Abstract

The present work sought to develop a biopolymeric film incorporated with brown propolis extract, which served as an antimicrobial barrier, in addition to having the potential to be used as food packaging. The raw material (propolis) in natura was evaluated in terms of moisture and ash contents, and indicated a percentage of 4,30 and 0,54%, respectively. Propolis extracts were obtained using two techniques. First the maceration technique and later the ultrasound extraction technique, which is performed using two different equipment: ultrasonic bath and ultrasonic tip sonicator. In both cases, two different solvents were used: water and 80% ethanol. The extracts were evaluated for their pH, antioxidant activity and total phenolic compounds, and for the aqueous extract the pH obtained was 5,89, the percentages of antioxidant activity varied between 7,34 ± 0,12 and 37,04 ± 1,19% and the total phenolic compounds varied between 2,40 ± 0,03 and 16,29 ± 0,81 mg GAE.g-1 b.s. For the ethanol extract, the pH was 5,19 and the total antioxidant activity and the total phenolic compounds varied between 93,41 ± 0,09 and 94,28 ± 0,43% and 63,08 ± 2,41 and 147,45 ± 4,23 mg GAE.g-1 b.s., respectively. The extracts were incorporated into the formulated films using the casting technique, using 0,5 g of carrageenan as a biopolymer, 0,3 g of glycerol as a plasticizer, 75 mL of solvent and 15 mL of aqueous extract (obtained by technique D) and ethanolic (obtained by the F technique). To evaluate the films, thickness analyzes were performed, obtaining values of 0,051 ± 0,02 and 0,046 ± 0,01 mm for films containing ethanolic extract and aqueous extract, respectively. The mechanical properties were also analyzed, with a reduction of 56,5% for the ethanol extract and 15,8% for the aqueous extract in terms of tensile strength in relation to the control film, while for elongation and vapor permeability of water, the presence of the extract did not affect the properties of the films. In addition, all films demonstrated a character of total solubility in water. Furthermore, the films containing ethanolic extract were able to form inhibition halos against strains of Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria, which were 8,14 ± 0,31 and 6,81 ± 0,21 mm, respectively, evidencing the antimicrobial character of the propolis used and the respective active potential of the film.