Retrospective Study on the Hygienic Quality of Fresh Ricotta Cheeses
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Italian Journal of Food Safety 2018; volume 7:6911 Retrospective study on the hygienic quality of fresh ricotta Introduction Correspondence: Maria Luisa Scatassa, cheeses produced in Sicily, Italy Recently, the new trends of life style of Istituto Zooprofilattico Sperimentale della the consumer showed an increasing demand Sicilia “A. Mirri”, Via Gino Marinuzzi 3, 90129 Palermo, Italy. of traditional dairy products manufactured Tel.: +39.091.6565300 - Fax +39.091.6565332. Maria Luisa Scatassa,1 at the small dairy level (Gaglio et al., E-mail: [email protected] Isabella Mancuso,1 Sonia Sciortino,1 2014b). Furthermore, the consumers require Giusi Macaluso,1 Marisa Palmeri,1 foods processed without chemical preserva- Key words: Ricotta cheese; Microbial com- Luigi Arcuri,2 Massimo Todaro,3 tives and characterized by low-fat and high- munity; Lactic acid bacteria; hygienic quality; Cinzia Cardamone1 nutritional values. Ricotta could respond to food safety. the demands of consumers because it is 1Institute for Experimental Veterinary characterized by high quantity of proteins, Medicine of Sicily “A. Mirri”, Palermo; Acknowledgments: The Authors thanks V. low fat and salt content and other important 2Local Health Unit, Palermo; Alio, A. Carrozzo, B. Ducato and G. Oliveri 3 components, which give this product a high for their precious collaboration. Department of Agricultural, Food and nutritional value (Guatemim et al., 2016). Forest Sciences, University of Palermo, Ricotta is a fresh dairy product that has Contributions: the authors contributed equally. Italy soft, grainy, thick, lightly sour taste and pre- sents a white colour. Usually, it can be eaten Conflict of interests: the authors declare no as a soft cheese but in Sicily is more fre- potential conflict of interests quently used as an ingredient in dishes and Abstract Received for publication: 19 July 2017. desserts. The name derived from the Latin Revision received: 12 October 2017. The present work was carried out to word re-cocta, literally recooked or cooked Accepted for publication: 14 October 2017. investigate the microbiological profile of twice. In Sicily it is generally manufactured Sicilian ewes’ ricotta cheeses during fifteen from the ewes’ whey remaining after the This work is licensed under a Creative years of investigations (2002-2016). The production of hard semi-cooked cheese Commons Attribution-NonCommercial 4.0 samples were collected between those con- (Pecorino Siciliano PDO) and fresh cheese International License (CC BY-NC 4.0). ferred to the Istituto Zooprofilattico (Vastedda della valle del Belìce PDO) but Sperimentale della Sicilia (IZSSi) Adelmo ©Copyright M.L. Scatassa et al., 2018 can be produced also with goat, cow and Licensee PAGEPress, Italy Mirri, Palermo (Italy), by the competent buffalo whey milk. Ricotta production tech- Italian Journal of Food Safety 2018; 7:6911 authority during official control, by food nology uses the principle of coagulation and doi:10.4081/ijfs.2018.6911 business operator in HACCP systems and in precipitation of the whey proteins such as research projects. Enterobacteriaceae, globulin and albumin favoured by whey Escherichia coli and coagulase-positive acidification at pH<5.6 and by heating at staphylococci (CPS) were found only in 80-90°C. During the production of Sicilian some samples. Bacillus cereus was detected ewes’ ricotta cheese, the whey is enriched Materials and Methods in c.a. 16% of samples but the level of con- with whole raw ewes’ milk (5-15%) and salt taminations did not reach the threshold that (0.5-1.5%) to increase the yield and Sample collections leads to significant toxin production. improve the organoleptic characteristics. A total of 1295 samples of ewes’ ricotta Pathogenic bacteria such as Listeria mono- Fresh ricotta is characterized by a short cheeses were collected between those con- cytogenes, Salmonella spp. and Brucella shelflife because of its high moisture level, ferred to the Istituto Zooprofilattico spp. were never detected. Furthermore, a high concentration of residual sugars and an Sperimentale della Sicilia (IZSSi) Adelmo total of 47 of lactic acid bacteria (LAB) initial pH above 6.0 which make this prod- Mirri, Palermo (Italy), by the competent strains were identified at species level by uct an excellent growth medium for a wide authority during official control, by food sequencing the 16S rRNA gene, resulting in range of microorganisms (Mancuso et al., business operator in HACCP systems and in the identification of 10 species belonging to 2014). The attributed shelflife of ricotta research projects. The samples were collect- four genera Enterococcus, Lactobacillus, cheese is generally comprised between 7-11 ed from 36 bakeries and pastry shops; from Lactococcus and Leuconostoc, commonly days under refrigerated storage (4°C). 233 markets and large-scale retail trade and employed as starter and non starter cultures Some of the microorganisms that grow from 365 dairy factories. The samples were in different traditional cheese. Results of in dairy products are able to produce unde- collected during fifteen years of investiga- this study highlighted an improvement of sirable reactions that deteriorate the tion (2002-2016). All samples to be micro- the hygienic conditions of the Sicilian organoleptic characteristics of cheese, while biologically investigated were transported ewes’ ricotta cheeses during the last ten other can potentially cause food-borne dis- under refrigeration at the laboratories of the years of investigation. This observation was eases (Lu et al., 2013). above-mentioned institute. confirmed from reduction of undesired The presence of these microorganisms microorganisms such as in dairy productions depends in some fac- Microbiological analysis and pH Enterobacteriaceae, E.coli and CPS, used tors such as the quality of raw material, the measurement to define the process hygiene criteria. respect of good practices of production and All samples were analyzed in accor- However, in order to improve the final qual- storage conditions (Ledenbach and dance with international standard or validat- ity of this product are needed further strate- Marshall, 2009). ed method: Total mesophilic count (ISO gy such as the dairy makers training, with In this context the present work was 4833), sulphite reducing anaerobes (ISO the aim to apply a good hygienic practices aimed to evaluate the microbiological qual- 15213), Enterobacteriaceace (ISO 4832), during the production. ity of several samples of Sicilian ewes’ Escherichia coli (ISO 16649-2); coagulase- ricotta cheese collected from dairy factories positive staphylococci (CPS, ISO 6888-2); and small and large distribution. Bacillus cereus (ISO 7932); yeasts and [page 68] [Italian Journal of Food Safety 2018; 7:6911] Article moulds (ISO 21527-1), Pseudomonas (ISO sequencing. The DNA from ricotta LAB tigation are reported in Table 1. The results 11059), enterococci on Kanamycin isolates was extracted using the InstaGene reported in this table are referred only to the Aesculin Azide aerobically incubated at Matrix kit (Bio-Rad laboratories, Hercules, microbial group that showed a microbiolog- 37°C for 24-48 h, rod-shaped lactic acid CA) according to the manufacturer’s ical grow (positive samples). bacteria (LAB) on de Man-Rogosa-Sharpe instructions. Crude cell extracts were used The total microbial count (TMC) and (MRS) agar, acidified to pH 5.4 with lactic as templates for the polymerase chain reac- LAB concentrations detected in this study acid (5 mol.L−1) and incubated anaerobical- tions (PCRs). PCRs were performed as were, on average, 1 Log cycle higher than ly for 48 h at 37°C; and mesophilic and described by Weisburg et al. (1991) using those reported in our previous work thermophilic coccus-shaped LAB on M17 the primers rD1 (5′-AAGGAGGT- (Mancuso et al., 2014), who studied the agar and incubated aerobically for 48 h at GATCCAGCC-3′) and fD1 (5′- sensory and microbiological evaluation of 30 and 44°C, respectively. Salmonella spp. AGAGTTTGATCCTGGCTCAG-3′). DNA traditional ovine ricotta cheese in modified was detected using ISO 6579 or AFNOR sequences were determined by using an atmosphere packaging (MAP). BIO 12/23-05/07 and Listeria monocyto- ABI PRISM 3130 Genetic Analyzer Furthermore, Spanu and coworkers (2017) genes using ISO 11290-1 or AFNOR BIO (Applied Biosystems, Carlsbad, CA, USA) always in a study conducted in MAP packed 12/11-03/04. Brucella spp. using Manual of and compared using a BLAST search in the ricotta cheese previously inoculated with Diagnostic Tests and Vaccines for GenBank/ EMBL/DDBJ database commercial biopreservatives and analyzed Terrestrial Animals, cap. 2.4.3.:2009. (http://www.ncbi.nlm. nih.gov). at different time of refrigerated storage The pH value of ricotta samples was found at t0 (after 5 h from the production) a monitored electrometrically using a lower concentration of TMC and LAB. This portable food and dairy pH meter HI3220- Statistical analysis may be due to different conditions of pack- Microbiological data of ricotta cheeses 02 (Hanna Instruments, Woonsocket, Rhode aging and refrigerated storage used in the divided in three 5-year periods of investiga- Island, USA). studies. Enterobacteriaceae and E. coli tion (2002-2006; 2007-2011; 2012-2016) were found in c.a. 21% and 13% of sam- were subjected to statistical analysis. The ples, respectively as reported by Fadda et Isolation, phenotypic characteriza- logarithm values of microbiological param- al. (2012) with an average values