Surfactants for the Effective Recovery of Salmonella in Fatty Foods

Abstract

Inhibitory concentrations of 8 surfactants were determined for Salmonella typhimurium and Salmonella enteritidis. Pure culture work resulted in the exclusion of Tween 20, Teepol 610 and Brij 35 and retention of Tergitol-7 (T-7), Tween 80 (TW 80), Triton X-100 (TX), Myrj 52S (M), and Arlacel 80 + Tween 60 (AT) for a study on the quantitative recovery of Salmonella in 45 naturally contaminated fatty foods. Replicate food samples (100 g) were preenriched overnight at 35 C in nutrient broth supplemented with 3%(w/v) surfactant except AT (10%). Serial dilutions of preenrichment cultures were selectively enriched overnight in tetrathionate brilliant green (43 C) and selenite cystine (35 C) broths and streaked on bismuth sulfite and brilliant green sulfa agar media. Recovery with all test surfactants was comparable to that obtained with nutrient broth controls; of 270 preenrichment cultures tested, only 7 false-negative results attributable to TX (3), AT (2), M (1), and nutrient broth control (1) were obtained. None of the surfactants consistently yielded greater populations of Salmonella for given foods or food categories; median counts for preenrichment cultures were 104–105 salmonellae/ml for low and high moisture foods and 106–107 salmonellae/ml for animal feeds. These results suggest that use of surfactants to facilitate detection of Salmonella in fatty foods is not warranted.

Problems associated with traditional hygiene swabbing: the need for in-house standardization

“…aureus colonies recovered by a small but significant amount (0·4 log values) over 24 h. When incubated within nutrient depleted environments, Gram‐positive organisms have been shown to lose their viability faster than Gram‐negative organisms (Liao and Shollenberger 2003; Egwari and Taiwo 2004) and the presence of antimicrobial substances can also reduce microbial numbers by causing injury or death (Mossel and Van Netten 1984). It has been suggested that surfactants, such as Tween 80 can injure certain cells (D’Aoust et al. 1982; Tsukamura 1991).…”

“…aureus colonies recovered by a small but significant amount (0AE4 log values) over 24 h. When incubated within nutrient depleted environments, Gram-positive organisms have been shown to lose their viability faster than Gram-negative organisms (Liao and Shollenberger 2003;Egwari and Taiwo 2004) and the presence of antimicrobial substances can also reduce microbial numbers by causing injury or death (Mossel and Van Netten 1984). It has been suggested that surfactants, such as Tween 80 can injure certain cells (D'Aoust et al 1982;Tsukamura 1991). Similarly, studies have also implied that the chelating agent, ethylenediamine tetraacetic acid (EDTA) and the nonionic detergent, Triton-X-100, both used in swab wetting solutions, can cause cellular damage and affect the growth of Gram-negative bacteria (Wells et al 1998;Helander and Mattila-Sandholm 2000).…”

Development and application of a centrifugation-plating method to study the biodiversity of Bacillus species in rice products

“…Treatment with Tween 80 increased the recovery of B. cereus in raw rice products. Of the available surfactants, Tween 80 has proven to be the most effective in releasing cells from food matrices (D'Aoust et al, 1982;Gnanou Besse & Lafarge, 2001;Hale, Doores, & Walsh, 1990), so it was selected for this study. The food matrix, specifically the starch in cooked rice products, is then hydrolyzed and solubilized to assist the release of bacilli and to facilitate plating after centrifugation.…”

A rapid method for enumerating Salmonella in milk powders

“…Neither trypsin (1%) nor Tween 80 (1 %) alone or in combination adversely affected the viability of the Salmonella serotypes when incubated with pure cultures of the organisms in buffered peptone water, for 45min at 37°C. The non-toxic effects of these agents on microorganisms, including Salmonella, have been reported before (Peterkin & Sharpe 1980;DAoust et al, 1982).…”