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

Spanu, Carlo; Scarano, Christian; Spanu, Vincenzo; Pala, Carlo; Salvo, R. Di; Piga, Claudio A.; Buschettu, L.; Casti, Daniele; Lamon, Sonia; Cossu, F; Ibba, Michela; Santis, E.P.L. De

doi:10.1016/j.foodcont.2014.10.022

Cited by 11 publications

(13 citation statements)

References 20 publications

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“…Among the isolates the most represented serotype was 1/2a (93%) followed by serotype 1/2b (7%). Our results are in compliance with those found in the literature (Spanu and others , ,b,c). …”

Section: Resultssupporting

confidence: 94%

“…Subsequently floating curd is collected through the use of a perforated ladle and transferred into plastic moulds. The curd is then pressed in order to increase the drainage and dry salted (5% w/w) at a controlled temperature (10 to 12 °C) for about 10 d. The final product is individually packed in vacuum bags and stored at refrigeration temperature (Spanu and others , ). Large numbers of viable Listeria cells present in milk are killed by heat treatment applied during cheese‐making and whey protein coagulation (Villani and others ; Spanu and others ).…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have shown that the cheese‐making plants are characterized by areas with conditions that favor the L. monocytogenes growth, such as refrigeration temperature, moisture and high salt concentration (Unnerrstad and others ; Tompkin ; Ibba and others ; Spanu and others ). Several studies have found that L. monocytogenes contamination in Ricotta Salata is present in the surfaces of the product and has originated from the processing environment (Spanu and others , ).…”

Section: Introductionmentioning

confidence: 99%

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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: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…This explains the frequent recovery of L. monocytogenes on ricotta salata cheese rind (Spanu et al ., 2012 , 2015a ; Ibba et al ., 2013 ). Contamination of the inner paste is a rare finding and is generally associated with poor hygienic procedures during manual molding (Spanu et al ., 2015b ). Previous studies reported a prevalence of contamination ranging from 0.0% up to 30.0% of the samples (Pilo et al ., 2007 ; Spanu et al ., 2015a ).…”

Section: Discussionmentioning

confidence: 99%

“…3 kg weight, which is individually packed in vacuum bags as a whole or after cutting into wedges. Ricotta salata cheese is stored at refrigeration temperature and the attributed shelf-life differs from three weeks up to several months, depending on the food business operators (Spanu et al ., 2015b ). Ricotta salata cheese is often used in salads or many other dishes sliced, crumbled or grated without further heating.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the microbiological profile of vacuum-packed ricotta salata cheese during shelf-life

et al. 2016

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Ricotta salata cheese is a salted variety of ricotta traditionally made in Sardinia (Italy) from the whey remaining after the production of Pecorino Romano protected designation of origin or other sheep milk cheeses. Ricotta salata cheese is very critical for the possible growth of pathogenic and spoilage microorganisms. Sporadic cases of listeriosis associated with ricotta salata cheese have been reported over recent years. The objective of the present study was to assess the evolution of spoilage and pathogen microorganism of vacuum-packed ricotta salata cheese during the entire product shelf-life. The durability study was conducted on 18 vacuum-packed ricotta salata cheese samples analysed at the beginning of the shelf-life and after 60 and 90 days of refrigerated storage. Pathogens as Listeria monocytogenes and Bacillus cereus were never detected. During shelf-life total bacterial counts ranged between 7.90±0.64 and 9.19±0.58 CFU g-1 on the rind and between 2.95±0.68 and 4.27±1.10 CFU g-1 in the inner paste, while Enterobacteriaceae ranged between 4.22±0.66 and 5.30±0.73 CFU g-1 on the rind and 3.13±1.80 and 2.80±0.88 CFU g-1 in the inner paste. By considering the technology used, the intrinsic properties and the almost total absence of competing microflora, ricotta salata cheese can support the growth of spoilage and pathogen microorganisms originating from the processing environment. The high level of total bacterial counts and Enterobacteriaceae observed both on the rind and in the inner paste suggests contamination of the product from the processing environment. Therefore, a strict implementation of hygiene during processing is essential in order to reduce the load of environmental contaminants that may grow during refrigerated storage.

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Occurrence and behavior of Bacillus cereus in naturally contaminated ricotta salata cheese during refrigerated storage

et al. 2016

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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

Cited by 11 publications

References 20 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

Evolution of the microbiological profile of vacuum-packed ricotta salata cheese during shelf-life

Occurrence and behavior of Bacillus cereus in naturally contaminated ricotta salata cheese during refrigerated storage

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