Physiochemical and antimicrobial properties of edible aloe/gelatin composite films

Edible antimicrobial aloe/gelatin composite films with different ratio of freeze–dried aloe leaf gel powder and gelatin (aloe/gelatin = 5/0, 4/1, 3/2, 2/3, 1/4 and 0/5) were fabricated. The thickness of the resulting films was between 0.055 (aloe/gelatin = 0/5) and 0.157 mm (aloe/gelatin = 4/1). The mechanical properties including maximum elongation, tensile strength, elongation at break and break strength were determined. The mechanical properties were increased with the increasing amount of gelatin used in the composite formulation. The tensile strength for composite films with the ratio of 4/1, 3/2, 2/3, 1/4 and 0/5 was 4.12, 5.29, 6.96, 11.47 and 37.76 MPa, respectively. Citrobacter freundii, Escherichia coli, Enterobacter aerogens, Serratia marcescens, Staphylococcus aureus and Bacillus cereus were used in antimicrobial activity test. The results showed that antimicrobial activities of the composite films increased as the amount of aloe gel powder used in the composite films increased. The average area of inhibitory zones for films with composition of aloe/gelatin = 1/4 and aloe/gelatin = 4/1 was 1.63–2.38 and 3.82–4.80 cm², respectively.