LAUSR

Objectives: The main aim of this study was to evaluate the effect of antimicrobial films on the shelf life of pasteurized milk. Methods: A natural antimicrobial agent, cinnamaldehyde, was incorporated in 0.5%, 1.0%, 1.5% and 2% concentrations in the middle layer of low density polyethylene (LDPE) three layer films by an extrusion process. Thickness of the inner layer were adjusted to 30 µm, 45 µm, and 60 µm and 2% PEG were added to some of the inner layer formulations. Active pillow packaging (5 cm × 7 cm) with 16 different formulas were obtained from the fabricated three layered active films by thermo-welding process and filled with pasteurized milk and stored at 4°C for 9 days. In order to see the effect of the active films on pasteurized milk quality, changes in total microbial counts monitored during the storage period. Results: During extrusion process, the mass loss of cinnamaldehyde were six times lowered when it was entrapped in the polymer matrix. All types of fabricated active films contributed to a reduction of total CFU growth rates in the pasteurized milk, when compared to plain (control) PE film, but the films coated with a thinner inner layer and films containing 2% PEG in the inner layers had a more pronounced effect than did the other films in inhibiting bacterial growth. Moreover, considering the five point hedonic scale sensory tests, film formulation number OM2I4 selected as the best one and its physical properties were compared to the control film. Practical Applications Considering the daily high usage of pasteurized milk in most countries and regarding the short shelf life and perishable properties of this food product, using of multi-layer active films containing cinnamaldehyde (a natural antimicrobial) for packaging of pasteurized milk can extend its typical shelf life (4 days) to 6 days at 4°C of storage.