Listeria monocytogenes growth potential in Ricotta salata cheese

Spanu, Carlo; Scarano, Christian; Spanu, Vincenzo; Penna, Claudio; Virdis, S.; Santis, E.P.L. De

doi:10.1016/j.idairyj.2011.09.006

Cited by 20 publications

(18 citation statements)

References 7 publications

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“…Our experimental data indicated that all Ricotta Salata analyzed was able to support the growth of L. monocytogenes because estimated growth potential (δ) was >0.5 log 10 cfu/g. These results are in compliance with previous studies that have shown a listeria growth potential in samples of cottage cheese contaminated by about 5 log 10 /g (Spanu and others ). The greater mean increase of L. monocytogenes was observed between T 0 and T 6 in the ricotta sample that was vacuum packed and stored at a temperature of thermal abuse (8 °C).…”

Section: Resultssupporting

confidence: 93%

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Coroneo

Carraro

Aissani

et al. 2015

Journal of Food Science

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Ricotta Salata is a traditional ripened and salted whey cheese made in Sardinia (Italy) from sheep's milk. This product is catalogued as ready-to-eat food (RTE) since it is not submitted to any further treatment before consumption. Thus, foodborne pathogens, such as Listeria monocytogenes, can represent a health risk for consumers. In September 2012, the FDA ordered the recall of several batches of Ricotta Salata imported from Italy linked to 22 cases of Listeriosis in the United States. This study was aimed at evaluating the presence and virulence properties of L. monocytogenes in 87 samples of Ricotta Salata produced in Sardinia. The ability of this product to support its growth under foreseen packing and storing conditions was also evaluated in 252 samples. Of the 87 samples 17.2% were positive for the presence of L. monocytogenes with an average concentration of 2.2 log10 cfu/g. All virulence-associated genes (prfA, rrn, hlyA, actA, inlA, inlB, iap, plcA, and plcB) were detected in only one isolated strain. The Ricotta Salata samples were artificially inoculated and growth potential (δ) was assessed over a period of 3 mo. The value of the growth potential was always >0.5 log10 cfu/g under foreseen packing and storing conditions. This study indicates that Ricotta Salata supports the L. monocytogenes growth to levels that may present a serious risk to public health, even while stored at refrigeration temperatures.

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Section: Resultssupporting

confidence: 93%

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Coroneo

Carraro

Aissani

et al. 2015

Journal of Food Science

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“…The prevalence of contamination of ricotta salata produced in Sardinia is estimated around 20% (Ibba et al, 2013;Spanu et al, 2015). This level can result, when ricotta is stored at refrigeration temperatures for up to two months, in concentration of the pathogens of approximately 10 7 log 10 cfu g À1 , potentially harmful to human health (Spanu et al, 2012). The present study was aimed to validate the temperature-time combinations able to reduce L. monocytogenes concentration of 5 log cfu g À1 , considered sufficient to comply with the food safety objective of <100 cfu g À1 for the products placed on the market during their shelf-life (EC, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…The manufacturing process result in cheese wheels weighing approximately 3 kg with a pH of 6.1e6.9, a W of 0.940e0.970, moisture of 50e60% (<50% if intended for grating), fat of 28e33% and protein of 14e23% (Spanu et al, 2012. The final product is individually packed in vacuum bags and stored at refrigeration temperature with a set shelflife which differs from three weeks up to several months, depending on the food business operators.…”

Section: Introductionmentioning

confidence: 99%

“…Contamination of whey cheeses with L. monocytogenes origins from the processing environment and is localized almost exclusively on the rind, with a reported prevalence in ricotta salata of approximately 20% (Ibba et al, 2013;Lioliou, Litopoulou-Tzanetaki, Tzanetakis, & Robinson, 2001;Pintado & Malcata, 2000;Spanu, Scarano, Ibba, Spanu, & De Santis, 2015). The intrinsic properties of ricotta salata support the growth of L. monocytogenes, once onto the product, to level as high as 7.0 log 10 cfu g À1 of rind, potentially harmful to human health (Spanu et al, 2012). Ricotta salata produced in Sardinia is mainly exported in North America and in other European countries.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of post-lethality thermal treatment conditions on the reduction of Listeria monocytogenes and sensory properties of vacuum packed ricotta salata cheese

et al. 2015

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“…Several recent studies have focused on the growth potential of L. monocytogenes in different RTE food products (Awaiwanont, Smulders, & Paulsen, 2015;Coroneo et al, 2016;Dalzini et al, 2014;Grassi, Nucera, Lomonaco, & Civera, 2013;Jesus et al, 2016;Lahou & Uyttendaele, 2017;Michellon et al, 2016;Sahu, Kim, Ferguson, Zink, & Datta, 2017;Sant'Ana, Barbosa, Destro, Landgraf, & Franco, 2012;Skalina & Nikolajeva, 2010;Spanu et al, 2012;Uyttendaele et al, 2009). These studies intended the classification of foods in the appropriate food category specified in Reg.…”

Section: Resultsmentioning

confidence: 99%

Growth potential of Listeria monocytogenes in ready‐to‐eat Feta cheese‐based sauce stored at 4°C

Andritsos

Kallitsis²,

Roukas

2018

Journal of Food Safety

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Listeria monocytogenes is now a well‐known foodborne pathogen of particular importance in ready‐to‐eat (RTE) refrigerated foods given the psychrotrophic character and ubiquitous nature of the bacterium. The objective of the current research was to assess the growth potential of L. monocytogenes in RTE cheese‐based (Feta) sauce. For this to occur, samples of Feta cheese‐based sauce (ca. 1% NaCl, pH = 4.6, 900 ppm sorbic acid) were artificially contaminated with a mixture of two L. monocytogenes strains and were stored aerobically at 4°C for 30 days. Growth potential (δ) of L. monocytogenes in Feta cheese‐based sauce was calculated at −1.2 log CFU/g for the 30‐day shelf‐life (i.e., δ < 0.5 log CFU/g). Findings of this study indicate that Feta cheese‐based sauce containing 900 ppm of sorbic acid as preservative is unable to support the growth of L. monocytogenes, thus the food safety criterion for pathogen enumeration not exceeding the limit of 100 CFU/g should apply during the shelf‐life of the product, as stated by Commission Regulation (EC) No. 2073/2005. Practical applications Contamination of acidic cheese‐based spreadable products, with pH ≤ 4.6 and/or water activity (i.e., Aw) > 0.94, with different bacterial species during the manufacturing process, could limit considerably the shelf‐life of these RTE products. Moreover, among other possible contaminants, the ubiquitous psychrotrophic pathogen L. monocytogenes may pose a serious threat for the microbiological safety of such products, like a Feta cheese‐based sauce with the aforementioned characteristics. Challenge testing for assessing the risk from L. monocytogenes presence during shelf‐life of this product is, therefore, deemed necessary and can provide us with useful information regarding possible pathogen containment due to product's composition and characteristics. Conclusively, even if the Feta cheese‐based sauce described in this study is contaminated with low numbers of L. monocytogenes at levels below the limit of detection (i.e., absence in 25 g), then the organism will not exceed 100 CFU/g by the end of product's shelf‐life.

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Listeria monocytogenes growth potential in Ricotta salata cheese

Cited by 20 publications

References 7 publications

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Detection of Virulence Genes and Growth Potential in Listeria monocytogenes Strains Isolated from Ricotta Salata Cheese

Comparison of post-lethality thermal treatment conditions on the reduction of Listeria monocytogenes and sensory properties of vacuum packed ricotta salata cheese

Growth potential of Listeria monocytogenes in ready‐to‐eat Feta cheese‐based sauce stored at 4°C

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