Raw Milk Cheese Production Research Articles

Staphylococcus aureus Isolated From Traditional Artisanal Raw Milk Cheese from Southern Brazil: Diversity, Virulence, and Antimicrobial Resistance Profile

Staphylococcus aureus is one of the primary pathogenic agents found in cheeses produced with raw milk. Some strains of S. aureus are enterotoxigenic, possessing the ability to produce toxins responsible for staphylococcal food poisoning when present in contaminated foods. This study aimed to genotypically characterize, assess the antimicrobial resistance profile, and examine the enterotoxigenic potential of strains of S. aureus isolated from artisanal colonial cheese. Additionally, a bacterial diversity assessment in the cheeses was conducted by sequencing the 16S rRNA gene. The metataxomic profile revealed the presence of 68 distinct species in the cheese samples. Fifty-seven isolates of S. aureus were identified, with highlighted resistance to penicillin in 33% of the isolates, followed by clindamycin (28%), erythromycin (26%), and tetracycline (23%). The evaluated strains also exhibited inducible resistance to clindamycin, with nine isolates considered multidrug-resistant (MDR). The agr type I was the most prevalent (62%) among the isolates, followed by agr type II (24%). Additionally, ten spa types were identified. Although no enterotoxins and their associated genes were detected in the samples and isolates, respectively, the Panton-Valentine leukocidin gene (lukS-lukF) was found in 39% of the isolates. The presence of MDR pathogens in the artisanal raw milk cheese production chain underscores the need for quality management to prevent the contamination and dissemination of S. aureus strains.

Phenotypic and genotypic characterization of antimicrobial resistances reveals the effect of the production chain in reducing resistant lactic acid bacteria in an artisanal raw ewe milk PDO cheese

Antimicrobial resistance (AMR) is a significant public health threat, with the food production chain, and, specifically, fermented products, as a potential vehicle for dissemination. However, information about dairy products, especially raw ewe milk cheeses, is limited. The present study analysed, for the first time, the occurrence of AMRs related to lactic acid bacteria (LAB) along a raw ewe milk cheese production chain for the most common antimicrobial agents used on farms (dihydrostreptomycin, benzylpenicillin, amoxicillin and polymyxin B). More than 200 LAB isolates were obtained and identified by Sanger sequencing (V1-V3 16S rRNA regions); these isolates included 8 LAB genera and 21 species. Significant differences in LAB composition were observed throughout the production chain (P ≤ 0.001), with Enterococcus (e.g., E. hirae and E. faecalis) and Bacillus (e.g., B. thuringiensis and B. cereus) predominating in ovine faeces and raw ewe milk, respectively, along with Lactococcus (L. lactis) in whey and fresh cheeses, while Lactobacillus and Lacticaseibacillus species (e.g., Lactobacillus sp. and L. paracasei) prevailed in ripened cheeses. Phenotypically, by broth microdilution, Lactococcus, Enterococcus and Bacillus species presented the greatest resistance rates (on average, 78.2 %, 56.8 % and 53.4 %, respectively), specifically against polymyxin B, and were more susceptible to dihydrostreptomycin. Conversely, Lacticaseibacillus and Lactobacillus were more susceptible to all antimicrobials tested (31.4 % and 39.1 %, respectively). Thus, resistance patterns and multidrug resistance were reduced along the production chain (P ≤ 0.05). Genotypically, through HT-qPCR, 31 antimicrobial resistance genes (ARGs) and 6 mobile genetic elements (MGEs) were detected, predominating Str, StrB and aadA-01, related to aminoglycoside resistance, and the transposons tnpA-02 and tnpA-01. In general, a significant reduction in ARGs and MGEs abundances was also observed throughout the production chain (P ≤ 0.001). The current findings indicate that LAB dynamics throughout the raw ewe milk cheese production chain facilitated a reduction in AMRs, which has not been reported to date.

Cross-sectional, commercial testing, and chromatographic study of the occurrence of antibiotic residues throughout an artisanal raw milk cheese production chain

This study investigated antibiotic utilization in artisanal dairies and residue occurrence throughout the raw milk cheese production chain using commercial testing (Charm KIS and Eclipse Farm3G) and UHPLC-QqQ-MS/MS and LC-QqQ-MS/MS. The cross-sectional survey results revealed gaps in the producers’ knowledge of antibiotic use. Commercial testing detected antibiotic levels close to the LOD in 12.5 % of the samples, mainly in raw milk and whey, with 10.0 % testing positive, specifically in fresh and ripened cheeses, indicating that antibiotics are concentrated during cheese-making. Chromatographically, several antibiotics were identified in the faeces of healthy animals, with chlortetracycline (15.7 ± 34.5 µg/kg) and sulfamethazine (7.69 ± 16.5 µg/kg) predominating. However, only tylosin was identified in raw milk (3.28 ± 7.44 µg/kg) and whey (2.91 ± 6.55 µg/kg), and none were found in fresh or ripened cheeses. The discrepancy between commercial and analytical approaches is attributed to compounds or metabolites not covered chromatographically.

Growth of methicillin-resistant Staphylococcus aureus during raw milk soft cheese-production and the inhibitory effect of starter cultures

The consumption of raw milk or raw milk products might be a potential risk factor for the transmission of methicillin-resistant Staphylococcus aureus (MRSA). Therefore, we studied MRSA growth during raw milk soft cheese-production. Furthermore, we investigated the inhibitory effect of four starter cultures (Lactococcus lactis, Lacticaseibacillus rhamnosus, Lactiplantibacillus plantarum, Lactobacillus helveticus) on the growth of MRSA in a spot-agar-assay and in raw milk co-culture following a cheesemaking temperature profile. During the initial phases of raw milk cheese-production, MRSA counts increased by 2 log units. In the ripening phase, MRSA counts only dropped slightly and remained high up to the end of the storage. Comparable MRSA counts were found in the rind and core and strain-specific differences in survival were observed. In the spot-agar-assay, all four starter cultures showed strong or intermediate inhibition of MRSA growth. In contrast, in raw milk, only Lactococcus lactis strongly inhibited MRSA, whereas all other starter cultures only had minor inhibitory effects on MRSA growth. Our results indicate that MRSA follow a similar growth pattern as described for other S. aureus during raw milk soft cheese-production and illustrate the potential use of appropriate starter cultures to inhibit MRSA growth during the production of raw milk cheese.

Optimization of Raw Ewes' Milk High-Pressure Pre-Treatment for Improved Production of Raw Milk Cheese.

Serra da Estrela protected designation of origin (PDO) cheese is manufactured with raw milk from Bordaleira and/or Churra Mondegueira da Serra da Estrela sheep breeds. Several socio-environmental shortcomings have reduced production capacity; hence, treatments that may contribute to its efficient transformation into cheese are welcome. High-pressure processing (HPP) milk pre-treatment may contribute to a cheese yield increment, yet optimization of processing conditions is warranted. An initial wide-scope screening experiment allowed for pinpointing pressure intensity, holding time under pressure and time after HPP as the most important factors influencing curd yield. Based on this, a more targeted screening experiment allowed for selecting the range of experimental conditions to be used for an experimental design study that revealed an HPP treatment at 121 MPa for 30 min as the optimum for milk processing to improve curd yield (>9%) and effectively maintain the beneficial cheese microbiota; the optimum was validated in a final experimental framework.

Cultures of Fermentation

Cultures of Fermentation

Effectiveness of a bacteriophage cocktail in reducing cheese early blowing caused by Escherichia coli

Gas production and subsequent food spoilage from the appearance of fissures, cracks or holes are undesirable consequences of saprophytic E. coli growth in cheese. Hence, the development of E. coli growth inhibitors is of special interest in soft and raw milk cheese production. This study investigates the inhibitory effect of a cocktail of four selected coliphages on the growth of E. coli in cheese and its ability to inhibit cheese early blowing. The microbiological analysis showed that the evolution of total bacterial counts during cheese-making and ripening was comparable among control and phage inoculated cheeses. Nevertheless these results also revealed a reduction in E. coli growth at the beginning of fermentation with phage treatment. Additionally, image analysis of cheese slices showed a noteworthy reduction in the number of cheese eyes and the area occupied by gas holes throughout cheese ripening. Thus, the use of bacteriophages as biocontrol agents provides an effective approach to combat cheese early blowing without noticeably altering the microbiological or physicochemical parameters of these fermented foods.

Raw Milk Microbiota Modifications as Affected by Chlorine Usage for Cleaning Procedures: The Trentingrana PDO Case.

Milk microbiota represents a key point in raw milk cheese production and contributes to the development of typical flavor and texture for each type of cheese. The aim of the present study was to evaluate the influence of chlorine products usage for cleaning and sanitizing the milking equipment on (i) raw milk microbiota; (ii) the deriving whey-starter microbiota; and (iii) Trentingrana Protected Designation of Origin (PDO) cheese microbiota and volatilome. Milk samples from three farms affiliated to a Trentingrana PDO cheese factory were collected three times per week during a 6-weeks period in which a sodium hypochlorite detergent (period C) was used and during a subsequent 6-weeks period of non-chlorine detergent usage (period NC). Samples were subjected to microbiological [Standard Plate Count; coliforms; coagulase-positive staphylococci; and lactic acid bacteria (LAB)] and metagenomic analysis (amplification of V3-V4 regions of 16S rRNA gene performed on Illumina MiSeq platform). In addition, cheese volatilome was determined by SPME-GC-MS. In the transition from period C to period NC, higher SPC and LAB counts in milk were recorded. Milk metagenomic analysis showed a peculiar distinctive microbiota composition for the three farms during the whole experimental period. Moreover, differences were highlighted comparing C and NC periods in each farm. A difference in microbial population related to chlorine usage in bulk milk and vat samples was evidenced. Moreover, chlorine utilization at farm level was found to affect the whey-starter population: the usually predominant Lactobacillus helveticus was significantly reduced during NC period, whereas Lactobacillus delbrueckii had the exact opposite trend. Alpha- and beta-diversity revealed a separation between the two treatment periods with a higher presence of L. helveticus, L. delbrueckii, and Streptococcus thermophilus in cheese samples after NC detergent period. Cheese volatilome analysis showed a slight decrease in lipolysis during C period in the inner part of the cheese wheel. Although preliminary, these results suggest a profound influence on milk and cheese microbiota, as well as on raw milk cheese production and quality, due to the use of chlorine. However, further studies will be needed to better understand the complex relationship between chlorine and microbiota along all the cheese production steps.

CalcPEFDairy: A Product Environmental Footprint compliant tool for a tailored assessment of raw milk and dairy products

A compliant tool (CalcPEFDairy) to determine the Product Environmental Footprint (PEF) of Dairy products has been developed following the Product Environmental Footprint Category Rules (PEFCR) v.6.3 guidance and the 2018 approved PEFCR for Dairy products. CalcPEFDairy is a new tool that simplifies and reduces the work for LCA practitioners when implementing the PEFCR for Dairy products. On contrary to traditional LCA software, CalcPEFDairy includes all the emission models needed to calculate farm and crop cultivation direct emissions and it also implements the specific calculation formulas stated in the PEFCR such as the Circular Footprint and Data Quality Requirement formulas. Moreover, the PEF compliant datasets provided by the Life Cycle Data Network are incorporated in the tool as source of secondary data. To demonstrate the accuracy of the tool a traditional dairy farm in Catalonia (Northwest of Spain) was assessed and the results compared with the European representative PEF compliant datasets for the production of raw milk, cheese and yoghurt. In addition to the environmental profile, CalcPEFDairy has determined the case study's environmental single score (ESS) for the production of raw milk (1.0 × 10−4) cheese (9.7 × 10−6) and yoghurt (1.4 × 10−5); these ESS results are within the range of the ESS obtained from the analysed EF-datasets. The data sets' average ESS for raw milk is 9.9 × 10−5 ± 1.1 × 10−5, while for cheese and yoghurt are 1.5 × 10−5 ± 3.1 × 10−6 and 1.9 × 10−5 ± 3.4 × 10−6 respectively. A 78% of the raw milk production ESS is attributed to the dairy farm activities while, the raw milk production stage affects in a 87.4% and 80.1% to the ESS for cheese and yoghurt respectively.

Non-thermal approach to Listeria monocytogenes inactivation in milk: The combined effect of high pressure, pediocin PA-1 and bacteriophage P100

Non-thermal food processing and replacement of chemical additives by natural antimicrobials are promising trends in the food industry. The objective of the present work was to evaluate the effect of a process which combines mild high hydrostatic pressure – HHP (200 and 300 MPa, 5 min, 10 °C), phage Listex™ P100 and the bacteriocin pediocin PA-1 as a new non-thermal process for destruction of Listeria monocytogenes (104 CFU mL−1 or 107 CFU mL−1) in milk. For inoculum levels of 104 CFU mL−1, HHP combined with phage P100 eliminated L. monocytogenes immediately after pressurization. When L. monocytogenes was inoculated at levels of 107 CFU mL−1, a synergistic effect between phage P100, pediocin PA-1 and HHP (300 MPa) on the inactivation of L. monocytogenes was observed during storage of milk at 4 °C. For non-pressure treated samples inoculated with phage or pediocin or both, L. monocytogenes counts decreased immediately after biocontrol application, but regrowth was observed in a few samples during storage. Phage particles were stable during refrigerated storage for seven days while pediocin PA-1 remained stable only during three days. Further studies will have to be performed to validate the findings of this work in specific applications (e.g. production of raw milk cheese).

Retroinnovación y sustentabilidad socioecológica: el caso de quesos campesinos de leche cruda en el Golfo de Arauco, Chile

Con métodos cualititativos analizamos los procesos de resistencia y (retro) innovación construidos y defendidos por una comunidad de productores de quesos crudos en el Golfo de Arauco (Chile); territorio marcado por el monocultivo forestal. Su existencia y viabilidad económica, desafía la industria forestal y el marco regulatorio existente, particularmente las normas higienistas de pausterización. Confirmamos la hipótesis que el pastoreo local y la producción de quesos con base en leche cruda involucran conocimientos y prácticas antiguas y nuevas, permite la reproducción socioecológica territorial, y responde a la complejidad temporal de las economías campesinas, articulando una red de productores, intermediarios y consumidores.

Control of Staphylococcus aureus in dairy herds in a region with raw milk cheese production: farmers\u2019 attitudes, knowledge, behaviour and belief in self-efficacy

BackgroundContagious mastitis is an important disease in dairy cattle, and the causative agent S. aureus can also impair raw milk cheese quality. In a confined region in eastern Switzerland attitude, knowledge and behaviour towards S. aureus und S. aureus control was assessed in 90 dairy farmers with communal alpine pasturing including raw milk cheese production with the aid of a questionnaire.ResultsForty-three out of 90 questionnaires were returned (48% return rate). Farmers perceived reproductive problems as most important in their dairy herds followed by respiratory disease and diarrhoea in young stock. Most frequently stated as important motivating factors to participate in S. aureus control were “avoiding negative news about cheese quality in the press” followed by “I want to be proud of my somatic cell counts again”. Most frequently chosen and identified as important constraining factors were “I fear that the authorities dictate and the farmers are not heard” followed by “costs to control S. aureus are too high because of premature culling” and “I am afraid to be forced to cull genetically valuable cows”. Farmers with an experience of a S. aureus problem in their dairy herds had a significantly better knowledge about contagiosity and clinical manifestation of different S. aureus genotypes than farmers with no self-reported experience of a S. aureus problem. Veterinarians were indicated as the most important experts, farmers seek advice in case of mastitis and most farmers suggested subsidising bacteriological milk analysis as an incentive to motivate farmers towards S. aureus control.ConclusionAccording to the results an improved knowledge transfer on S. aureus to dairy producers and an integrative approach to a S. aureus control program with subsidising milk analysis will be most promising to improve the S. aureus situation in this confinded region of eastern Switzerland. Veterinarians should cover a key role in consulting farmers during the control program.

Short communication: Characterization of Staphylococcus aureus isolated along the raw milk cheese production process in artisan dairies in Italy

Staphylococcus aureus is a common cause of food-borne intoxications. Several staphylococcal food poisoning outbreaks have been linked to consumption of raw milk cheeses and artisanal cheese production. However, information on Staph. aureus isolated from artisanal raw milk cheeses and small-scale dairy production environments is very limited. Therefore, we aimed to characterize Staph. aureus isolated along the artisanal raw milk production chain by determining (1) the population structure, and (2) the presence/absence of enterotoxin genes, mecA/C, and pvl. We collected 276 samples from different production stages (raw milk, whey, curd, brine, drying worktops, and cheese) at 36 artisan dairies in Italy. A total of 102 samples from 25 dairies tested positive for Staph. aureus, with 80% positive samples among the tested artisan cheeses. All isolates were further characterized by spa typing and PCR screening for staphylococcal enterotoxin genes, the mecA/mecC genes characteristic for methicillin-resistant Staph. aureus, and the pvl gene encoding Panton-Valentine leukocidin. The 102 isolates represented 15 different spa types and were assigned to 32 different Staph. aureus strains. The spa type most frequently detected was t2953 (30%), which is associated with genotype B strains causing high within-herd levels of bovine mastitis. In addition, 3 novel spa types (t13269, t13277, and t13278) were identified. Although none of the strains harbored mecA/mecC or pvl, 55% of the isolates exhibited at least one enterotoxin gene. Many strains were present in samples from multiple dairies from different regions and years, highlighting the spread of Staph. aureus in small-scale cheese production plants. Our findings demonstrate that enterotoxigenic Staph. aureus and in particular t2953 (genotype B) isolates commonly occur in artisanal dairies and raw milk cheeses in Italy. It is particularly alarming that 80% of the artisan cheeses sampled in our study were positive for Staph. aureus. These findings stress the need for effective measures preventing staphylococcal food poisoning by limiting Staph. aureus growth and enterotoxin formation along the production chain and in the final product.

Real Deal or No Deal? A Comparative Analysis of Raw Milk Cheese Regulation in Australia and France

Australia’s regulatory framework has resulted in the standardisation of cheese production based on pasteurisation. Up until early 2015, regulations effectively prohibited raw milk cheese-making in Australia and thus stifled artisanal on-farm production. Although the introduction of Food Standards Australia New Zealand Standard 4.2.4 has allowed the production of certain hard, low-moisture raw milk cheeses, the new standard is rigid and does not encourage new entrants into the emerging raw milk cheese consumer market. This article compares the Australian system with the French raw milk cheese regulation and production system, and argues that its approach in encouraging and supporting small farmhouse artisanal traditional raw milk cheese is beneficial to both producer and consumer, and has not resulted in any significant health risks. The Australian approach amounts to a missed opportunity to encourage the emergence of a value-added industry with local and export potential, and is at odds with important movements in food policy, such as recognition of the value of localism and terroir.

A PRODUÇÃO DE QUEIJO COLONIAL ARTESANAL NO MUNICÍPIO DE SEARA, ESTADO DE SANTA CATARINA, FRENTE À LEGISLAÇÃO BRASILEIRA

O objetivo deste trabalho foi investigar a situação da produção do queijo Colonial artesanal (QCA), um produto típico da região sul do Brasil, produzido e comercializado no município de Seara, oeste do Estado de Santa Catarina, sob o ponto de vista da adequação das condições de trabalho perante a Instrução Normativa nº 30 de 2013 do Ministério da Agricultura, Pecuária e Abastecimento, legislação vigente no Brasil que regulamenta o uso de leite cru para a fabricação de queijos com tempos de maturação inferiores a 60 dias. Para a realização do trabalho foram entrevistados 12 produtores, aplicando uma pesquisa qualitativa a campo para o diagnóstico situacional, utilizando como instrumento um formulário semi-estruturado. Os resultados obtidos indicaram que a situação da produção do QCA na área investigada não estava adequada no que diz respeito à legislação vigente, pois os produtores não têm acesso às condições necessárias para realizar análises (do leite, água e queijo), garantir a qualidade dos produtos com implantação das Boas Práticas de Ordenha e Fabricação ou certificar a propriedade como livre de zoonoses, como estabelecido pela Normativa.

Consensus categorization of cheese based on water activity and pH—A rational approach to systemizing cheese diversity

Development of science-based interventions in raw milk cheese production is challenging due to the large diversity of production procedures and final products. Without an agreed upon categorization scheme, science-based food safety evaluations and validation of preventive controls would have to be completed separately on each individual cheese product, which is not feasible considering the large diversity of products and the typically small scale of production. Thus, a need exists to systematically group raw milk cheeses into logically agreed upon categories to be used for food safety evaluations. This paper proposes and outlines one such categorization scheme that provides for 30 general categories of cheese. As a base for this systematization and categorization of raw milk cheese, we used Table B of the US Food and Drug Administration’s 2013 Food Code, which represents the interaction of pH and water activity for control of vegetative cells and spores in non-heat-treated food. Building on this table, we defined a set of more granular pH and water activity categories to better represent the pH and water activity range of different raw milk cheeses. The resulting categorization scheme was effectively validated using pH and water activity values determined for 273 different cheese samples collected in the marketplace throughout New York State, indicating the distribution of commercially available cheeses among the categories proposed here. This consensus categorization of cheese provides a foundation for a feasible approach to developing science-based solutions to assure compliance of the cheese processors with food safety regulations, such as those required by the US Food Safety Modernization Act. The key purpose of the cheese categorization proposed here is to facilitate product assessment for food safety risks and provide scientifically validated guidance on effective interventions for general cheese categories. Once preventive controls for a given category have been defined, these categories would represent safe havens for cheesemakers, which would allow cheesemakers to safely and legally produce raw milk cheeses that meet appropriate science-based safety requirements (e.g., risk to human health equivalent to pasteurized milk cheeses).

Short communication: Heat-resistant Escherichia coli as potential persistent reservoir of extended-spectrum β-lactamases and Shiga toxin-encoding phages in dairy.

Here we report the isolation of heat-resistant Escherichia coli from raw milk cheeses. Detection of the heat-resistance markers clpK and orfI by PCR was followed by phenotypical confirmation of increased heat-resistance. These strains were Shiga toxin-negative and, although several were found to be multidrug resistant, no plasmids encoding extended-spectrum β-lactamases (ESBL) were found in any of the isolates. The aim of this study was to assess the potential of these strains to acquire ESBL plasmids and a modified Shiga toxin-encoding phage. Only 4 ESBL-encoding, heat-sensitive E. coli strains were isolated from 1,251 dairy samples (2/455 raw milk and 2/796 raw milk cheese samples). One incompatibility group FII plasmid (CTX-M-14, 79.0 kb) and 3 incompatibility group I1 plasmids (CTX-M-15, 95.2, 96.1, and 97.8 kb) were fully sequenced and de novo assembled. All 4 plasmids are readily transferred to heat-resistant E. coli isolates in plate matings (9.7×10-5 to 3.7×10-1 exconjugants per recipient) and, to a lesser extent, in milk (up to 7.4×10-5 exconjugants per recipient). Importantly, the plasmids are stably maintained during passaging in liquid media without antimicrobial pressure. The heat-resistant isolate FAM21805 was also shown to be capable of acting as donor of all 4 ESBL plasmids. In addition, 3 of 11 tested ESBL exconjugants of heat-resistant strains were lysogenized by the modified Shiga toxin-encoding phage 933W ∆stx::gfp::cat. The higher fraction of heat-resistant E. coli (93 of 256 isolates) compared with the estimated 2% previously predicted based on genomic prevalence of heat resistance genes seems to indicate a selection advantage in the raw milk cheese production environment. The combination of 2 factors may lead to said advantage: increased survival during thermization of raw milk (heating to subpasteurization temperatures) and increased survival rates during cheese ripening. Should these strains acquire ESBL-encoding plasmids, Shiga toxin-encoding phages, or both, these genetic elements would profit from the selection advantage of their host and become more abundant in this particular environment, which in turn could lead to an increased threat to consumers of raw milk products.

Staphylococcus aureus reservoirs during traditional Austrian raw milk cheese production.

Sampling approaches following the dairy chain, including microbiological hygiene status of critical processing steps and physicochemical parameters, contribute to our understanding of how Staphylococcus aureus contamination risks can be minimised. Such a sampling approach was adopted in this study, together with rapid culture-independent quantification of Staph. aureus to supplement standard microbiological methods. A regional cheese production chain, involving 18 farms, was sampled on two separate occasions. Overall, 51·4% of bulk milk samples were found to be Staph. aureus positive, most of them (34·3%) at the limit of culture-based detection. Staph. aureus positive samples >100cfu/ml were recorded in 17·1% of bulk milk samples collected mainly during the sampling in November. A higher number of Staph. aureus positive bulk milk samples (94·3%) were detected after applying the culture-independent approach. A concentration effect of Staph. aureus was observed during curd processing. Staph. aureus were not consistently detectable with cultural methods during the late ripening phase, but >100 Staph. aureus cell equivalents (CE)/ml or g were quantifiable by the culture-independent approach until the end of ripening. Enterotoxin gene PCR and pulsed-field gel electrophoresis (PFGE) typing provided evidence that livestock adapted strains of Staph. aureus mostly dominate the post processing level and substantiates the belief that animal hygiene plays a pivotal role in minimising the risk of Staph. aureus associated contamination in cheese making. Therefore, the actual data strongly support the need for additional sampling activities and recording of physicochemical parameters during semi-hard cheese-making and cheese ripening, to estimate the risk of Staph. aureus contamination before consumption.

Awareness and perceptions of food safety of artisan cheese makers in Southwestern Ontario: A qualitative study

The purpose of this research is to assess the food safety awareness and perceptions of artisan cheese makers using semi-structured interviews based on the Risk Analysis Framework. Seventeen in-depth interviews were conducted with managers and workers from 11 different cheese companies. The interviews were audio taped and transcribed verbatim. Common themes in the interview transcripts were identified. Listeria monocytogenes was perceived to be the most concerning biological hazard due to its potential impact on human health and business. Overall, the impact on food safety from chemical and physical hazards was perceived to be limited, and to be more of an occupational health and safety risk. More than half of the respondents supported the production of safe raw milk cheese, although they acknowledged the inherent bacterial hazards associated with it. Current food safety management systems such as HACCP were perceived to be excessively complicated due to the over-emphasis on documentation and the need for additional resources. Cheese safety education was valued, but participation was limited due to the lack of financial resources and available programs in the region.

Behaviour of Escherichia coli strains during semi-hard and hard raw milk cheese production

The behaviour of two Escherichia coli strains, one with a high and the other with a low thermotolerance phenotype, was investigated during production and ripening of Swiss semi-hard and hard raw milk cheese. In semi-hard cheese, counts of E. coli increased during production, before a log-linear decrease occurred during ripening, with a faster rate of reduction in core than in rind samples, and faster reduction of the more heat-sensitive strain in rind samples. Nevertheless, at the end of semi-hard cheese ripening, E. coli were present at least at 1.3 log10 cfu g−1 in rind samples and remained detectable by enrichment of core samples. During the first day of hard cheese production, both E. coli strains were almost completely inactivated. Detection by enrichment was possible in one of twelve spiked cheeses after 16 weeks, indicating the potential of a thermotolerant E. coli strain to survive until the end of ripening.