Growth and survival of selected pathogens in margarine-style table spreads.
Although margarine-style table spreads can have a pH above 4.6 and a water activity greater than 0.85, there is some question if such products can support the growth of pathogenic bacteria. The objective of this study was to evaluate the growth and survival of Staphylococcus aureus, Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella typhi in 60-percent- and 70-percent-vegetable-oil, margarine-style, water-in-oil-emulsion table spreads stored at different temperatures. Samples of 25 grams of each table spread were inoculated with 1 x 10(3) cells of each bacterial mixture. The samples were stored at 5 degrees C, 7 degrees C, and 21 degrees C, and the microbial population in colony-forming units per gram (CFU/gram) was enumerated over time. In almost all storage conditions, bacterial levels were shown to decrease over time. Inactivation was observed in (listed from fastest to slowest, respectively) S. aureus, L. monocytogenes, E. coli O157:H7, and S. typhi. Growth was observed only for S. typhi in table spreads stored at 21 degrees C, but the rate of growth was extremely slow. Based on these findings, the table spreads evaluated in this study are not potentially hazardous foods, and cold temperature storage is not necessary from a food safety perspective.
Guentert
Ann M
AM
Department of Food Science, Purdue University, 1160 Food Science Building, West Lafayette, Indiana 47907-1160, USA. guentert@foodsci.purdue.edu
Linton
Richard H
RH
D003080:Cold Temperature; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000254:growth & development / Q000302:isolation & purification; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D008089:Listeria monocytogenes / Q000254:growth & development / Q000302:isolation & purification; D008383:Margarine / Q000032:analysis / Q000382:microbiology*; D012485:Salmonella typhi / Q000254:growth & development / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000254:growth & development / Q000302:isolation & purification
D008383:Margarine