A Novel Method for the Reduction of Numbers of Listeria monocytogenes Cells by Freezing in Combination with an Essential Oil in Bacteriological Media

Abstract

The use of multiple freeze (-20 degrees C)-thaw cycles in combination with isoeugenol and polysorbate 80 was investigated as a method for the reduction of numbers of Listeria monocytogenes cells in a bacteriological medium. Three freeze (1 h, -20 degrees C)-thaw cycles in the presence of isoeugenol at concentrations of 0, 100, and 300 ppm resulted in average L. monocytogenes reductions of 0.69, 2.65, and 3.3 log10 MPN (most probable number) per ml, respectively. Increasing the number of freeze-thaw cycles further decreased cell numbers, with reductions of nearly 5 log10 MPN/ml being obtained with six freeze-thaw cycles. Freeze-thaw cycles were effective in reducing cell numbers at isoeugenol concentrations down to 25 ppm. Rapid freezing rates with liquid nitrogen were found to be less effective in reducing numbers of L. monocytogenes cells. Two rapid freeze-thaw cycles in the presence of 100 ppm isoeugenol and polysorbate 80 resulted in a reduction of 1.45 log10 MPN/ml. Two freezing (-20 degrees C) cycles involving slow freezing and thawing rates with samples being held frozen for 6 h for each cycle resulted in reductions larger than those obtained with faster freezing rates. It was found that complete thawing in freeze-thaw cycles was not necessary to achieve bactericidal action. The application of multiple freeze-thaw cycles in combination with low concentrations of isoeugenol could effectively reduce numbers of L. monocytogenes cells in bacteriological media.

Anti-inflammatory and antinociceptive activities A of eugenol essential oil in experimental animal models

“…Traditional uses of clove oil include use in dental care, as an antiseptic and analgesic (Oliveira et al, 2007). It is active against oral bacteria associated with dental caries and periodontal disease (Cai & Wu, 1996) and effective against a large number of other bacteria (Burt & Reinders, 2003;Larhsini et al, 2001;Cressy et al, 2003;Friedman et al, 2002) and virus (Kim et al, 2001). Previous studies have reported biological activities of eugenol including antifungal (Gayoso et al, 2005;Manohar et al, 2001;Chami et al, 2005), anticarcinogenic (Zeng et al, 1992), antiallergic (Kim et al, 1998;Corrêa et al, 2008), antimutagenic activity (Miyazawa & Hisama, 2001), antioxidant (Ogata et al, 2000) and insecticidal (Park et al, 2000) properties.…”

Role of Growth Temperature in Freeze-Thaw Tolerance of Listeria spp

“…After freezing (Ϫ18°C) in laboratory media or in foods and a single thawing cycle, survival depended on strain, freezing medium, and the presence of glycerol as cryoprotectant (13,14). The freezing and thawing of bacteria grown at 30°C, in combination with essential oil, has been explored as one means to reduce the pathogen in foods (8). The possible role of the general stress sigma factor (sigma B) in survival of bacteria grown at 30°C and exposed to repeated freezing and thawing was also investigated (43).…”

Antimicrobial Activity and Chemical Composition of Two Essential Oils and Eugenol from Flower Buds of

“…(0.049 μLmL -1 ). The antimicrobial properties of clove essential oil were tested and showed inhibitory activity to Listeria monocytogenes, Campylobacter jejuni, Salmonella enteritidis, Bacillus cereus, Escherichia coli and Staphylococcus aureus [53,54]. Essential oils of clove possess high antimicrobial properties [16].…”