Efficacy of limon oil essential and sodium hypoclorite or an combined washing in killing natural microbiota on cherry tomatoes

TORRES SOPORSKY, MARÍA; SAGUIR F.M.; SAJUR SA

Córdoba

Congreso; Congreso Argentino de Microbiología General.SAMIGE. 2015; 2015

SAMIGE

EFICACIA DE ACEITE ESENCIAL DE LIMÓN E HIPOCLORITO DE SODIO O DE LAVADOS SIMULTANEOS PARA ELIMINAR LA MICROBIOTA NATURAL DE TOMATES CHERRYEFFICACY OF LIMON ESSENTIAL OIL AND SODIUM HYPOCHLORITE OR SIMULTANEOUS WASHINGS IN KILLING NATURAL MICROBIOTA ON CHERRY TOMATOES Saguir Fabiana M., Torres Soporsky Maria, Sajur Silvia A,Facultad de Bioquímica, Química y Farmacia. Universidad Nacional de Tucumán. Ayacucho 471. Tucumán, Argentina. ssajur@hotmail.comVegetables such as tomato are possible vehicles of pathogenic microorganisms and outbreaks of food-borne illnesses have been linked to their consumption. Chlorine water (50?200 mg/l) is widely used to sanitize fruits and vegetables as well as fresh-cut produces. However, there is an increasing interest in developing alternative sanitizers for washing due to its limited efficacy, the possible carcinogenic chlorinated compounds formation as well as the occurrence of taste and odor defect in treated products. Essential oils, which are considered GRAS substances have been reported to have antimicrobial, antioxidative and food preservative properties. In a previous work demonstrated that lemon essential oil (LEO) added at 100 ppm in tomato puree removed Escherichia coli without adversely affect the organoleptic properties The aim of this study was therefore to evaluate the effectiveness of aqueous solutions of LEO (100 ppm) and sodium hypochlorite 5% (NaCLO) when applied individually and simultaneously as potential antimicrobial surface treatments to eliminate the natural microbiota on tomatoes. Cherry tomatoes were rinsed with sterile distilled water to determine the initial population, and then intact portions were cut into pieces (2 g) using sterile knife and used in experiments. Washing treatments were performed by immersing portions (10 g) in 50 ml of each treatment solution (LEO or NaCLO for 5, 10 and 15 min or LEO:NaCLO in proportions 50:50, 25:75, 75:25 for 5 min) in sterile glass flask with continuous agitation at 120 rpm (22±2ºC). At the end of contact time, the respective treatment solution was drained off and the treated samples were rinsed with sterile peptone water by shaking for 2 min. Serially diluted samples were spread-plated (0.1 ml) in duplicates over plate count agar (PCA); MRS agar with 1.3 µg/ml of Pimaricin, pH 6.5 (MRS-P) and Mc Conkey agar pH 7.1 (MAC) for enumeration of aerobic mesophilic bacteria, lactic acid bacteria (LAB) and Gram negative non-LAB respectively. Treatments were realized by duplicate with respective controls. Tomato surfaces contained average population levels determined on PCA, MRS-P and MAC of 5.58±0.3, 3.69±0.2 and 3.61±0.2 cfu/g respectively. Treatments with LEO alone resulted in log10 reductions up to 3.0 cfu/g after 10 or 15 min washing while treatment with NaClO in complete reductions. However in this last case decolorization of tomatoes was observed. Washing treatments with EOL or NaClO alone for 5 min did not lead to complete log reduction, however the Gram negative counts on MAC decreased by 75 and 100%, respectively. For this washing time simultaneous treatments with ELO:NaClO in proportions 50:50 or 75:25 completely reduced microbial populations but not 25:75 respectively, thereby enhancing NaClO significantly ELO efficacy. In conclusion the washing treatment with EOL(75):NaClO(25) may be an important component of overall contamination reduction process in whole and fresh-cut vegetables.