Purpose: Evaluation of the antimicrobial effect of distillery ethanol and 'tsipouro' through diffusion and/or evaporation on ground beef stored in commercial packages.
Methods: Different concentrations of ethanol (38, 70, and 100% v/v) and 'tsipouro' (Greek alcoholic distillate) were applied as antimicrobials in packages of ground beef (500g). Antimicrobials were added in absorbent cloths (17x12mm; 17x24mm), which were placed underneath beef and soaked with 20, 30, 40, and 60 ml of antimicrobials. Moreover, cloths (7x10mm) supplemented with 10 ml of the respective antimicrobial were also mounted under the packaging film of each package. Packages were stored under 80%O2:20%CO2 at 7°C. Untreated samples served as controls. TVC, pseudomonads, B. thermosphacta, lactic acid bacteria, pH, color (L*,a*,b*), and odor were evaluated. The migrated ethanol to the ground beef was estimated by GC-FID. Measurements were performed on samples taken from the top and bottom of the package to investigate potential differences regarding the antimicrobial efficacy and migration of antimicrobials through evaporation and/or diffusion.
Results: B. thermosphacta dominated the microbial association of meat. Growth of all studied microorganisms was delayed by increasing the applied volume and concentration of ethanol/'tsipouro'. For instance, on day 3, when TVC on controls reached 7.5 log CFU/g, samples treated with 'tsipouro' followed the order: 6.0 log CFU/g (60 ml) > 6.4 log CFU/g (40 ml) > 6.7 log CFU/g (30 ml) > 7.0-7.3 log CFU/g (20 ml) resulting in 2-5 days shelf-life extension. Ethanol and 'tsipouro' also inhibited pseudomonads (by 1.0-2.0 log CFU/g) compared to controls. Gradual decrease of L* and a* was observed on controls, while samples treated with ethanol (especially 38%) and 'tsipouro' showed more stable, red color. With regards to GC, ethanol (component) was higher (P ≤ 0.05) on the bottom (diffusion) of the ground beef compared to the top (evaporation).
Significance: Such preservation methods may raise new perspectives on mild antimicrobial packaging in order to extend shelf life of perishable food products.