Analytical methods for food-contact materials additives in olive oil simulant at sub-mg kg-1 level.

Methods of analysis for four additives (two antioxidants, IRGANOX 245 and 1035; an ultraviolet absorber, CHIMMASORB 81; and an optical brightening agent, UVITEX OB) in olive oil are reported. These additives have the potential to migrate from food-contact materials into the European Union fatty food simulant olive oil, which is the most difficult matrix for analysis. The additives were chosen because they differed in their chemically active groups, had different functions within the polymer, have low proposed specific migration limits and are commonly used in food-contact materials such as polystyrenes and polyolefins. The proposed analytical methods for the additives are simple, rapid, inexpensive and also broadly applicable to the aqueous food simulants. All methods were evaluated by constructing calibration curves, measurement of recovery and precision, and determining the limits of detection. Most of the methods involve direct injection of an olive oil solution for high-performance liquid chromatography analysis with ultraviolet-visible or fluorescence detection. The methods allowed establishment of additive stability and measurement of migration of the selected additives into olive oil at different time-temperature conditions used in migration studies into food simulants.

Susceptibilities of Listeria species isolated from food to nine antimicrobial agents.

The agar dilution method was used to determine the activities of gentamicin, erythromycin, streptomycin, chloramphenicol, ampicillin, sulfamethazine, cephalothin, penicillin G, and tetracycline against 73 strains belonging to the genus Listeria (L. innocua, L. seeligeri, and L. monocytogenes). All strains were isolated from raw milk, cheese, the dairy processing plant, poultry, and the poultry slaughterhouse. Gentamicin, ampicillin, and erythromycin, of which the MICs for 90% of the strains tested for all three species were < or = 5.96 micrograms/ml, were found to be the most active agents studied. Most of the L. innocua strains isolated from poultry and the poultry slaughterhouse were resistant to tetracycline.