Viability of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes in butter, yellow fat spreads, and margarine as affected by temperature and physical abuse

Microbiological Attributes of Turkish Butters Sold Under Market Conditions

“…Salmonella can grow in butter at 25 8C and could not be eliminated by refrigeration or freezing (Sims et al, 1970). Holliday et al (2003) reported that Salmonella and E. coli O157.H7 can grow on the surface of sweet cream whipped salted butter exposed to high relative humidity at 21 8C.…”

“…Since the hygienic conditions of the manufacturing plants are inadequate, pathogen microorganisms can find access to the milk products (Soomro et al, 2002). According to Holliday et al (2003) contamination risk of butter with pathogens increases as portions of products are repeatedly removed from containers over long periods of time. Moisture may condense on the frozen or refrigerated products in warm places like kitchens and this may lead to pathogen growth.…”

Listeria spp. in the raw milk and dairy products in Antakya, Turkey

“…Among dairy products, yogurt received the least attention due to the fact that its high acidity and milk pasteurization are regarded to be effective barriers to the growth of pathogens including L. monocytogenes (Benkerroum et al, 2003). The low pH values (4.5) of sweet cream whipped unsalted butter and salted light butter samples possibly contribute to suppressing the growth of Salmonella, Escherichia coli O157:H7, and L. monocytogenes (Holliday, Adler, & Beuchat, 2003). The absence of Listeria spp.…”

Growth Potential Assessment of Listeria in Milk Fat Products by Challenge Testing

“…We were able to confirm here that droplet size as well as pH and preservative agents are key elements to prevent growth of L. monocytogenes. Previous literature also showed that several other factors, such as the inoculation technique used (Holliday and Beuchat 2003b;Voysey et al 2009b) as well as portion size (Maijala et al 2001), may also affect the behavior of L. monocytogenes.…”

“…The size of water droplets ranges from 5 to 30 μm, limiting the proportion of droplets that can be occupied by microorganisms. Indeed, it is generally reported that emulsions with droplets smaller than 10 μm (Bullock and Kenney 1969;Delamarre and Batt 1999;Holliday and Beuchat 2003b) provide an unfavorable environment for bacterial growth. This reduced bacterial growth may be explained by the fact that most cells are isolated in droplets that are not much larger than the bacterial cells themselves.…”