Controlled Release of Fungicidal Antimicrobials on Packaged Foods

Abstract

This paper presents the effect of polymer concentration on the release of fungicidal antimicrobial (AM) agent to prolonging the shelf life of packaged food. This project aimed to produce and test AM films with varying polymer ratio to control the release of fungicidal AM agent. The effects of potassium sorbate (PS) released on peanut and fresh breads was tested for nineteen days to determine the effect of AM agent to inhibit the growth of Aspergillus niger (A. niger). The microbe was cultured on a potato dextrose agar (PDA) medium to obtain the activity of AM film. AM film contains mixtures of CA: acetone in 15% w/w, 13% w/w and 10% w/w ratios. Each ratio was mixed with 8 ml PS (from stock solution containing 20 g PS in 80 ml distilled water). PS was used as the AM agent during film formation. The film was formed in a petri dish at room temperature and the mixture was degassed in a vacuum oven. The A. niger was cultured from the soil and the AM activities of the films gave a clear zone indicated around the film for seven days. PS incorporated into CA based film has the capacity to inhibit the growth of A. niger in peanuts and fresh bread. The release kinetics of PS from the films was obtained by studying the de-swelling properties of PS loaded film at room temperature (24 ̊C) and at 37°C. The diffusion coefficients of PS released through the film network were obtained to be between 1.97 x 10-8 m2s-1 – 5.29 x 10-7 m2s-1 at 24 ̊C and 1.3 x 10-10m2s-1 – 1.80 x 10-8 m2s-1 at 37 ̊C. The fractional release exponent n-values for the film ranges from 0.16 – 0.54 at 24 ̊C and 0.5 - 1.1 at 37 ̊C. The geometrical constant (k) ranges from 0.0063 – 0.19 at 24 ̊C and 0.000041 – 0.0057 at 37 ̊C. The average swelling ratio of the films also ranges from 1.026 - 1.56 at 24 ̊C and 0.71 - 1.51 at 37 ̊C. SEM images were obtained to observe the morphology of the films and UV-Vis spectrophotometer was also used to study the amounts of PS released from the films.