2. Materials and methodsExtraction and purification of essential oils and mucilageFor the extraction of essential oils, dried rosemary plant materials distilled within 24 hours in a steam distiller with an aqueous phase recycling system, using a plant material:water ratio of 2: 1. The distillation time was approximately 2 hours and the oil obtained was separated from the aqueous solution and dried by treating with anhydrous Na2SO4. Each essential oil was transferred to a dark glass vial filled to the brim and kept at a temperature of 4°C until use (Meepagala et al., 2002). Also for mucilage extraction, cactus stems were stripped of their skin and cut into cubes (1 cm3). The samples were homogenized (20% w/v) in distilled water. The slurry was centrifuged for 10 min at 4,500 rpm and the supernatant was precipitated in ethanol and finally dried (Sáenz et al., 1992). Liposomal oil preparation Multilamellar vesicles were prepared according to the thin film hydration method (Gortzi et al., 2006). The lipid solution was prepared by dissolving 5 mg/ml phosphatidylcholine, 1 mg/ml cholesterol, and 0.1 mg/ml essential oil in 3 mg/ml chloroform. Phosphatidylcholine from fresh egg yolk and chloroform were obtained from Sigma Chemicals Company Ltd. (St. Louis, MO, USA). Cholesterol was purchased from Fluka (Buchs, Switzerland). 5.0 ml of the lipid solution was introduced into a 100 ml round bottom flask. The solvent was evaporated in a Heidolph Laborota rotary evaporator (model 4000; Heidolph Laborota, Schwabach, Germany), at 35–40 °C, under reduced pressure (13–14 mm Hg). The obtained dry lipid film was hydrated with 5 ml of distilled water. Mechanical agitation of lipids in aqueous medium was performed with the rotary evaporator apparatus at 37 °C and by manual agitation in the water... in the center of the paper... Shimadzu UV-Vis 1601 spectrophotometer. The curve standard was established using gallic acid. Microbiology For microbiological analysis, banana slices (10 g) were aseptically removed from each package and transferred to a sterile plastic package to which 90 ml of sterile Ringer's solution was added. The sample and Ringer solution were mixed for 60 seconds using a Stomach, 400 Circulator (Seward Ltd, Thetford, UK). Portuguese standard methods, EN ISO 4833 (ISO, 2003), were followed for enumeration of total aerobic plate count (TPC). Statistical analysis The research was established according to a complete randomized design with three replications. All data obtained from the study were analyzed using analysis of variance (ANOVA) and using SPSS computer software, version 15.0 (SPSS Inc., Woking, United Kingdom). Means were compared using the LSD test at the P level<0,05.