Safety Of Cheese Research Articles

Reduced-sodium cheeses: Implications of reducing sodium chloride on cheese quality and safety.

Sodium chloride (NaCl) universally well-known as table salt is an ancient food additive, which is broadly used to increase the storage stability and the palatability of foods. Though, in recent decades, use of table salt in foods is a major concern among the health agencies of the world owing to ill effects of sodium (Na) that are mostly linked to hypertension and cardiovascular diseases. As a result, food scientists are working to decrease the sodium content in food either by decreasing the rate of NaCl addition or by partial or full replacement of NaCl with other suitable salts like potassium chloride (KCl), calcium chloride (CaCl2 ), or magnesium chloride (MgCl2 ). However, in cheese, salt reduction is difficult to accomplish owing to its multifaceted role in cheese making. Considering the significant contribution in dietary salt intake (DSI) from cheese, researchers across the globe are exploring various technical interventions to develop reduced-sodium cheeses (RSCs) without jeopardizing the quality and safety of cheeses. Thus, the purpose of this study is to provide an insight of NaCl reduction on sensory, physicochemical, and technofunctional attributes of RSCs with an aim to explore various strategies for salt reduction without affecting the cheese quality and safety. The relationship between salt reduction and survival of pathogenic and spoilage-causing microorganisms and growth of RSCs microflora is also discussed. Based on the understanding of conceptual and applied information on the complex changes that occur in the development of RSCs, the quality and safety of RSCs can be accomplished effectively in order to reduce the DSI from cheese.

Role of chitosan and some plant parts wraps as alternative interior edible coat surrounding semi-hard cheese in inhibiting fungal growth and mycotoxins migration

Food packaging is a part of food preservation concept. Exposed surfaces of cheese are vulnerable to mold contamination from several sources. Thus, cheese spoilage is generally confined to molds. Two mycotoxigenic fungal isolates were used in this study Penicillium citrinum and Penicillium verrocosum, a new method was applied in this study as a safe alternative composite coat to conventional internal coat (EVOH) in semi-hard cheese (Gouda). The new chitosan composite coat is based on chitosan/potato starch and/or thyme and safflower powders. These new coats are adjusted for thickness homogeneity, using the standard methods of ASTM with certain modification. This study aimed at investigating the effects of these wraps and the conventional coat on fungal growth and mycotoxins migration to cheese. Our results illustrated that the use of chitosan coat alone or enriched with HPPs succeeded in controlling the growth of the tested fungi invading cheese and significantly reducing the mycotoxins migrated amounts to cheese. The addition of this plant material (HPPs) ameliorated the capability of EVOH to reduce fungal growth and the majority of the tested mycotoxins migration amounts. Our results may achieve a significant impact on shelf-life extension and cheese safety during transport and trade when the addition of HPPs is applied.

Application of Bacteriocin-Like Inhibitory Substances (BLIS)-Producing Probiotic Strain of Lactobacillus plantarum in Control of Staphylococcus aureus in White-Brined Cheese Production

The aim of this study was to investigate the antimicrobial activity of an autochthonous probiotic strain of bacteriocin-like inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production. inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production.

Application of Bacteriocin-Like Inhibitory Substances (BLIS)- Producing Probiotic Strain of Lactobacillus plantarum in Control of Staphylococcus aureus in White-Brined Cheese Production

The aim of this study was to investigate the antimicrobial activity of an autochthonous probiotic strain of bacteriocin-like inhibitory substances (BLIS)-producing Lactobacillus plantarum, previously isolated from a Tulum cheese and satisfied technological criteria as adjunct culture in cheese production, in reducing Staphylococcus aureus during production and ripening of white-brined cheeses. Cheeses were manufactured in two trials from pasteurized milk artificially contaminated with S. aureus to the mean level of 6.243 log MPN mL-1. Lb. plantarum BG33 was added at 1% as adjunct to the starter culture. The study was also carried out with control group cheeses produced without the adjunct culture. S. aureus counts were monitored for up to 90 days by BAM’s 5-tube MPN method and each positive tube of MPN (most probable number) method was confirmed by PCR amplification of a 400 bp fragment of the nuc gene, which encodes the thermostable nuclease of S. aureus. The capacity of Lb. plantarum BG33 to reduce S. aureus count was found as 0.9 log unit on the 18th day of ripening. After 39 and 59 days of ripening, Lb. plantarum BG33 lowered S. aureus count by 1.9 and 2.0 log units, respectively, when compared to control group cheeses in which it was lowered by 0.5 and 1.0 log units, respectively. As a result, the BLIS activity of Lb. plantarum BG33 throughout ripening of white-brined cheese could make it useful as bioprotective adjunct culture in white-brined cheese production to prevent S. aureus growth which is an important foodborne pathogen in respect of safe cheese production.

Research of heat treatment influence of milk on quality and safety of hard cheeses

The object of research is raw milk used for the production of hard cheeses by milk processing enterprises of Ukraine. The quality of raw milk is especially important, a key factor determining the effectiveness of the milk processing industry. Without milk, which meets certain requirements, it is impossible to organize the production of high-quality products. Special requirements are placed on the quality of raw milk intended for the cheese production. One of the most problematic places is improving the quality and cheese suitability of raw milk and improving the technological process for the production of natural hard cheesesDuring the study, laboratory (biochemical and microbiological) research methods are used to determine the quality indicators of raw milk and finished products, as well as their microbial contamination. And for processing the results of the study, methods of mathematical statistics are used.The work shows that bacterial contamination of raw milk, which exceeds the normative limit values, poses a threat to both the technological process of cheese making and the quality of the finished product. Methods are proposed for preventing a decrease in the yield of cheese and deterioration in its quality due to prolonged storage of milk at low temperatures. It is proved that the best results are obtained with ultra-high-temperature processing of milk with an exposure of 2–4 s. And also, that high-temperature and, especially, ultra-high-temperature (UHT treatment) is a very effective way to destroy bacterial microflora and improve the quality of raw milk by such an indicator as a «pollution tank». This allows to increase the cheese ability of raw milk. High temperatures of heat treatment of milk lead to changes in the salt and protein composition of milk. These changes should have both negative consequences – a deterioration in the rennet coagulation of milk and the synergistic properties of the clot, and a positive result consisting in an increase in the transfer of milk solids, primarily whey proteins, to clot and cheese.

Transformation of raw ewes' milk applying “Grana” type pressed cheese technology: Development of extra-hard “Gran Ovino” cheese

This work was carried out to pursue a double objective: to improve the hygienic safety of cheeses produced from raw ewes' milk; and to produce a new typology of raw ewes' milk through the application of “Grana” technology for which the name “Gran Ovino” was chosen. With this in mind, raw milk from an individual farm was transformed under controlled conditions at a dairy pilot plant. The production technology included the partial skimming of the evening and morning milk mixture by cream surfacing and the addition of a natural whey starter cultures (NWSC) prepared with four selected Streptococcus thermophilus strains (PON6, PON244, PON261 e PON413). Ten microbial groups were investigated by plate counts from raw milk until ripened cheeses. Lactic acid bacteria (LAB) were in the range 104–105 CFU/ml before NWSC addition. After curdling, this group increased by 3 log cycles and was counted at 106 CFU/g after curd cooking. A rapid pH drop (to 6.05) was registered after almost 3 h from NWSC addition. The levels of members of the Enterobacteriaceae family were at about 103 CFU/ml in raw milk and decreased after curd cooking to 1 log cycle. A similar behavior was shown by the other undesired microbial groups and a complete disappearance of staphylococci was registered. The microbiological counts of 9-month ripened cheeses showed the dominance of LAB and undetectable levels of the undesired bacteria. MiSeq Illumina was applied to better investigate the bacterial composition of ripened cheeses and this technique evidenced that the majority of OTUs belonged to Lactobacillus and Streptococcus genera. The final cheeses were characterized by 67.65% dry matter of which 41.85% of fats and 47.02% of proteins. The main cheese fatty acids were palmitic, oleic and myristic acids and the saturated fatty acids/unsaturated fatty acids ratio was 2.17. Forty-one volatile compounds, including acids, esters, ketones, alcohols, aldehydes, phenols and one terpene were emitted from the cheese. Sensory evaluation showed a general appreciation for the new cheese product by judges.

FDA's Cheese and Cheese Products Compliance Program guideline criteria for non-toxigenic Escherichia coli: A retrospective analysis of impacts on domestic and imported cheeses

The U.S. Food and Drug Administration's (FDA) 2015 Domestic and Imported Cheese and Cheese Products Compliance Program Guidelines (CPG) (U.S. FDA, 2015) consider cheeses to be adulterated if non-toxigenic Escherichia coli levels of greater than 10 most probable number per gram (MPN/g) and less than 100 MPN/g are found in 3 or more of 5 subsamples. It is unclear if, or how, these standards impact food safety, and the extent to which these standards affect domestic and imported cheese commerce. We conducted a retrospective analysis of microbiological data from FDA's Domestic and Imported Cheese Compliance Program for cheese samples collected between January 1, 2004 and December 31, 2006. Out of 3,007 cheese samples tested by the FDA for non-toxigenic E. coli, 76% (2,300) of samples contained E. coli levels that exceeded 10/g. Of these samples, 68% (2,047) exceeded 2009 regulatory guidelines of 100/g. In comparison, only 7.7% (232) of tested cheese samples exceeded European Union (EU) standards (<1,000 E. coli/g) and 170 (5.7%) of samples exceeded the 1998 CPG criteria (<10,000 E. coli/g). Mexican-style soft, semi-soft, and soft ripened cheeses were the cheese types most impacted by application of the 2015 non-toxigenic E. coli standards. At E. coli levels of 10/g and 100/g, there was no statistically significant association with the presence of Listeria monocytogenes or Salmonella. However, associations between S. aureus levels of 10,000 cfu/g and presence of Salmonella and L. monocytogenes were statistically significant, indicating that EU regulations targeting S. aureus as the pathogen of concern may be more appropriate for cheese safety assessment.

Evaluation of Mycobacterium avium subsp. paratuberculosis survival during the manufacturing process of Italian raw milk hard cheeses (Parmigiano Reggiano and Grana Padano)

Mycobacterium avium subsp. paratuberculosis (MAP), the agent of paratuberculosis in ruminants, is suspected to be involved in the aetiology of some human diseases. Notably, the consumption of milk and dairy products is considered to be the main route of human exposure to MAP because of its ability to survive during pasteurization and manufacturing processes. The aim of this study was to investigate, through a microbiological challenge test, the survival of MAP during the manufacturing and ripening period of two Italian hard cheeses, Parmigiano Reggiano and Grana Padano, made from raw bovine milk. The challenge test was performed in two different phases: the creaming phase and the manufacturing phase.The creaming phase, which is the first step of cheese production, was reproduced in the laboratory employing raw cow's milk spiked with a MAP reference strain at a final concentration of 5.58 log10 CFU/mL. After the creaming at 18 °C and 27 °C for 12 h, a decrease of 0.80 log10 and 0.77 log10 was observed in partially skimmed milk, respectively.In the second phase, two batches of raw cow's milk (1000 L each) were inoculated with MAP reference and wild strains, respectively. Then, the entire manufacturing process for Parmigiano Reggiano and Grana Padano, both of Protective Designation of Origin (PDO), was reproduced in an experimental cheese factory, starting from a concentration in milk of 5.19 ± 0.01 and 5.28 ± 0.08 log10 CFU/mL of MAP reference and wild strains, respectively. Heating the curd at 53 °C for 20 min did not affect MAP survival, however a significant decrease (p < 0.05) in MAP viability was observed during the moulding phase and after salting in brine, regarding the wild strains and the reference strain, respectively. In addition, a significant decrease was observed during the ripening period, at which time the MAP concentration dropped below the limit of detection from the second and the third month of ripening, for the wild and reference strains, respectively.Taking into account the poor data availability about MAP survival in hard cheeses, this study may improve the knowledge regarding the effect of the cheese manufacturing process on the MAP dynamics, supporting also the safety of traditional raw milk hard cheeses.

Characteristics of ripened Tronchón cheese from raw goat milk containing legally admissible amounts of antibiotics

The aim of this study was to evaluate the transfer of the most widely used antibiotics in dairy goats from milk to cheese as well as their effect on the cheese-making process and cheese characteristics during ripening. Antibiotic-free milk was spiked individually with 7 veterinary drugs (amoxicillin, benzylpenicillin, cloxacillin, erythromycin, ciprofloxacin, enrofloxacin, and oxytetracycline) at an equivalent concentration of the European Union maximum residue limit. Spiked goat milk was used to make mature Tronchón cheeses, which were analyzed at 0, 30, and 60 d of maturation to determine pH, chemical composition, proteolytic and lipolytic activities, and color and textural properties. A sensory evaluation of 60-d ripened cheeses was carried out. Cheeses from raw antibiotic-free goat milk were made simultaneously to be used as reference. The cheese-making process was unaffected by the presence of most antibiotics evaluated. Only erythromycin and oxytetracycline significantly increased the time required for cheese production (122 ± 29 and 108 ± 25 min, respectively). However, variable amounts of antibiotics, ranging from 7.4 to 68%, were transferred from milk to cheese, with oxytetracycline and quinolones showing the highest retention rates. In general, antibiotic residues present in the cheeses at the beginning of maturation decrease significantly along time. Thus, β-lactams and erythromycin residues were not detectable after 30 d of ripening. However, relatively high concentrations of enrofloxacin (148 ± 12 µg/kg) and ciprofloxacin (253 ± 24 µg/kg) residues were found in the cheeses after 60 d of maturation. The quality characteristics of the Tronchón cheeses were only slightly affected by such substances, with few significant differences in the free fatty acid concentration and color and textural properties of the cheeses. Results herein indicate that the use of goat milk containing antibiotics, such as quinolones, at the European Union maximum residue limit for cheese production could adversely affect the safety of the final products because relatively high concentrations of these substances could be retained in soft and semi-mature cheeses, making it necessary to assess the risk for consumer health. Studies on the partition of the antibiotic substances during cheese-making, using specific technologies, would be convenient to guarantee the safety of cheese and related products.

ВЕТЕРИНАРНО-САНИТАРНАЯ ОЦЕНКА КАЧЕСТВА И БЕЗОПАСНОСТИ МОЛОКА И МОЛОЧНЫХ ПРОДУКТОВ, ИЗГОТОВЛЯЕМЫХ В ИНДИВИДУАЛЬНОМ ФЕРМЕРСКОМ ХОЗЯЙСТВЕ ТВЕРСКОЙ ОБЛАСТИ

The article presents the results of a study of the quality and safety of raw cow's milk, sour cream and cottage cheese, produced in a private farm in the Tver region. In the course of the work, regulatory documents were studied and organoleptic and physico-chemical researches were performed. In order to determine the food safety of dairy products, microbiological studies were conducted: QMAFAnM, the content of somatic cells and inhibitory substances, the number of Salmonella, coliforms, lactic acid microorganisms and S. aureus were determined). On the basis of the obtained results, it was established that the investigated milk can be allowed for sale and is quality raw material for the production of dairy products. Sour cream and cottage cheese from private production are benign, microbiologically pure and safe food.

Caracterización molecular y serológica de Escherichia coli en Quesos artesanales de seis departamentos de Honduras

Un estudio realizado durante el año 2015 donde se evaluó la calidad e inocuidad en quesos artesanales de seis departamentos de Honduras que están dentro de las regiones productoras de quesos del país. Los resultados de este estudio de calidad microbiología en este tipo de alimentos son algo alarmantes ya que el recuento de bacterias totales y coliformes fecales fueron superiores a 1 x 103 UFC/g lo cual supera los límites establecidos en reglamentos para este tipo de productos. Esto debido a malas prácticas de manufactura que puedan tener los pequeños y medianos productores. Escherichia coli es un patógeno que sirve como indicador de contaminación fecal en agua y alimentos. Esta bacteria ha evolucionado a ser un versátil patógeno intestinal que puede albergar varios genes de virulencia que crean lesiones en células intestinales. Objetivos: El objetivo principal fue clasificar molecularmente los patotipos y grupos filogenéticos de E. coli de cepas obtenidas a partir de muestras de quesos. Adicionalmente se logró la clasificación de las cepas en serotipos lo cual brindo más información y coincidencias epidemiológicas con otros estudios de otras fuentes. El estudio comprendió el año 2016 donde se realizó toda la parte experimental y 2017 se concluyó el análisis de todos los datos obtenidos. Resultados: Un total de 48 cepas obtenidas del estudio del 2015 donde un 86% (n=41) fueron obtenidas de queso semiseco, y el resto de ellas de queso fresco y seco. Un 58% (n=28) amplificaron para dos patotipos principales EPEC (en un 54%) y ETEC (46%). El grupo filogenético predominante fue el B1 con un 50% (n=24). Los serogrupos predominantes en las cepas fueron O6, O8, O159. Conclusiones: El saber que existen patotipos que albergan factores de virulencia causantes de patologías intestinales; en alimentos de alto consumo como los quesos artesanales, es un problema de inocuidad alimentaria que debe tomarse en serio. Existen muchas preguntas que responder después de esta descripción de situación de un patógeno que puede causar brotes en cualquier momento.

Microbiological quality and safety of cheeses belonging to “Traditional Agri‐Food Products” (T.A.P.) produced in Southern Italy

AbstractThe aim of this study was to assess the microbiological quality and safety of some cheeses produced in Apulia region, Southern Italy, and classified as “traditional agri‐food products.” A total of 120 samples were collected and analyzed. From results, 82.5% of cheeses analyzed, had a satisfactory microbiological quality according to the European legislation. The coagulase positive Staphylococci (CPS) count was above the limits set by the European legislation in 17.5% of the samples analyzed. Within the 20 strains of Staphylococcus aureus (S. aureus) isolated, 12 were positive for the detection of the enterotoxin genes. Furthermore, nine strains of S. aureus were positive to reverse passive latex agglutination (SET‐RPLA) assay. One of the two samples of Cacioricotta di Vacca Fresco, with a CPS load of 3.02 × 105 cfu/g, showed unsatisfactory microbiological safety because was positive to SET‐RPLA. Based on the findings, it is essential to apply and maintain good hygiene practices throughout the food chain, especially for traditional agri‐food products, which are often produced in small family processing plants using production protocols based on the experience handed down from father to son.Practical applicationsThe traditional agri‐food products are foodstuffs much appreciated by consumers because of their organoleptic qualities and taste that brings back to the genuine flavors of the past. However, the hygienic quality and safety of these products is linked to the personal experience of food business operator and not to the regular checking of microbiological parameters that validate the acceptability of foodstuffs and their manufacturing, handling and distribution processes. The results of this study can contribute to the risk analysis for these particular products, and underline the need to apply and maintain good hygiene practices throughout the production chain.

Prevalence of Foodborne Pathogens on Cheeses Made from Farmstead Milk Processing Plants in Korea

To solve the problem of raw milk surplus, the Korean government encouraged the farmstead milk processing industry. However, the hygiene of farmstead dairy products has not been evaluated. Therefore, the microbiological analysis of farmstead cheeses was performed in this study. Farmstead cheeses (Berg, Colby, Cottage, Gouda, Mozzarella, String, Tilsiter, and Quark) were purchased from 16 dairy farms. In qualitative analysis, the presence of foodborne pathogens (Bacillus cereus, Escherichia coli, Clostridium perfringens, Salmonella, Staphylococcus aureus, Listeria monocytogenes, and Campylobacter spp.) were examined. Also, total aerobic bacteria, Pseudomonas spp., coliform, and E. coli, and yeast/mold were enumerated. Seventeen samples (37.8%) of 45 farmstead cheeses were contaminated with B. cereus and the highest detection rate was observed in String cheese. Two samples (4.4%) were E. coli positive and seven samples (15.6%) were S. aureus positive. Four other foodborne pathogens were not detected in all farmstead cheeses. Also, the mean levels of total aerobic bacteria, coliform, E. coli, and yeast/mold were 4.3 Log CFU/g, 1.4 Log CFU/g, 1.1 Log CFU/g, and 3.8 Log CFU/g, respectively. These results indicate that the food safety of farmstead cheese is extremely poor and, thus, the hygiene management of farmstead cheese should be improved to provide safe farmstead cheese to consumers.

Contribution of natural milk culture to microbiota, safety and hygiene of raw milk cheese produced in alpine malga.

Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes. With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested.. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli, staphylococcal toxins, Listeria monocytogenes, and Salmonella spp, pH and awwere determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga, in any case preserving bacterial biodiversity.

Microbiological criteria and ecology of commercially available processed cheeses according to the product specification and physicochemical characteristics

Although global cheese manufacturers release a variety of products onto the market, research on the microbiological quality and safety of cheese has focused mainly on conventional cheeses made from milk. Here, this study aimed to investigate commercially processed cheese products produced by mixing conventional cheeses after melting. Two approaches were used: a summary and comparison of legal definitions and standards/regulations regarding the microbiological criteria used by major cheese traders in the global market (Australia/New Zealand, China, European Union, Japan, Mexico, Republic of Korea, and the United States) and a comprehensive microbiological analysis of commercial products (n = 800), along with an assessment of salinity, pH, water activity, and heating conditions. The results of the literature search showed that major importing countries (China, Japan, Mexico, and the Republic of Korea) have stricter microbiological criteria for commercially available cheese products than major exporters (Australia/New Zealand, EU, and the USA). The former set limits with respect to the number of total coliforms in the product. Microbiological analyses were designed according to global standards and recommendations. No test sample contained detectable levels of Clostridium perfringens, enterohemorrhagic Escherichia coli, Listeria monocytogenes, Salmonella, or Staphylococcus aureus. In addition, no coliform bacteria (including E. coli) were detected. Overall, 79.9% of the samples contained detectable aerobic plate counts (1.0–7.8 log CFU/g); these levels varied significantly according to product type (grated cheese > chunks; cream cheese > portions or sliced) (p < .05). There was no significant association between microbe levels and salinity, water activity, pH, and heating conditions. The results can be used to develop a comprehensive database about commercially processed cheese products available in the global market and, as such, may be helpful for both national authorities and cheese manufacturers when considering novel strategic management plans for microbiological quality and safety.

Use of starter culture of native lactic acid bacteria for producing an artisanal Mexican cheese safe and sensory acceptable

ABSTRACTUnpasteurized artisanal cheeses are a source of pathogens for humans. We isolated lactic acid bacteria (LAB) from raw milk and from cheeses made with raw milk, and formulate starter cultures for producing an artisanal Mexican cheese known as ‘Queso Bola de Ocosingo’. We evaluated six combinations of strains as starter culture-treatments. The proximate composition of the cheeses, the sensorial evaluation, and the microbiological safety of cheeses made with pasteurized milk was evaluated. The use of starter culture helped to maintain the pathogen microbial total count of pasteurized cheese below the standard limit maximums. The sensory judges did not find differences among the cheese elaborated with unpasteurized milk and that elaborated with pasteurized milk and the starter culture added. The starter culture formulated with LAB derived from unpasteurized cheese can be used for producing ‘Bola de Ocosingo’ cheese which is sensory acceptable and microbiological safe.

Effect of microbial control measures on farmstead cheesemaking and antimicrobial resistance of Staphylococcus aureus and Enterococcus spp. isolates

AbstractThe effect of microbial control measures in farmstead cheese making was evaluated in a small dairy farm in Gyeong‐gi province, Korea. Teat washing and pasteurization significantly (p &lt; .05) reduced the level of indicator bacteria (mesophilic aerobes, total coliforms, and Escherichia coli). However, farmstead cheeses were contaminated with increased levels of mesophilic aerobes, total coliforms, Staphylococcus aureus, and Enterococcus faecium during post‐pasteurization steps, including the cheesemaking process and ripening. S. aureus isolates from cheese samples exhibited antibiotic resistance to penicillin/ampicillin, whereas teat and milk samples showed resistance to erythromycin/ciprofloxacin. Enterococcus spp. isolates had the highest proportion of organisms resistant to erythromycin and tetracycline among multidrug‐resistant strains. To ensure the safety of farmstead cheese, customized management systems and intervention methods should be established by focusing on control measures for not only preprocessing and pasteurization but also post‐pasteurization steps.Practical applicationsOwing to renewed interest in specialty cheeses, small‐scale farmstead cheeses are actively produced worldwide. However, because of various manufacturing steps, including milking, pasteurization, ripening, and storage, farmstead cheese could pose a high risk for the presence of foodborne pathogens. In the current study, teat washing and milk pasteurization effectively reduced microbial contamination loads. However, farmstead cheeses were contaminated post‐pasteurization with increased levels of indicator and pathogenic microorganisms. Comprehensive management systems should be implemented and should focus not only on preprocessing and pasteurization but also on post‐pasteurization steps to ensure the safety of farmstead cheese.

Application of an antimicrobial packaging material from chicken bone gelatine and cinnamon bark oil to mozzarella cheese

SummaryChicken bones are mostly discarded even though they contain a considerable amount of proteins, which would allow them to be applicable as a protein film source. In this study, chicken bone gelatine (CBG) films were prepared and characterised after the addition of cinnamon bark oil (CBO) to confer antimicrobial activity. The incorporation of 1% CBO increased the tensile strength of the CBG film from 18.2 to 23.9 MPa, whereas elongation at break was decreased from 15.6% to 5.91% and water solubility from 88.9% to 62.2%. Antimicrobial activity of the CBG films against foodborne pathogens as well as their antioxidant activity increased with the increase in CBO concentration. When CBG film containing 1% CBO was used for wrapping mozzarella cheese inoculated with Listeria monocytogenes, the population of the bacterium decreased after 20 days in storage, indicating that CBG films can be applied for improving the microbiological safety of mozzarella cheese.

Effect of ‘in situ’ produced bacteriocin thermophilin T on the microbiological and physicochemical characteristics of Myzithra whey cheese

Myzithra whey cheese was made by the addition of ovine milk (10%) to whey, previously fermented by the bacteriocinogenic strain Streptococcus thermophilus ACA‐DC 0040, resulting in production of a bacteriocin (thermophilin T) titre at a concentration 40 960 ± 2560 AU/mL. The final antimicrobial activity in the ready‐to‐eat cheese was sufficient to inhibit the growth of coliforms and restrict the growth of bacteria of the Micrococcus group, thus contributing to and increased shelf life and the safety of cheese. A lower lactose content was observed in the cheese, which would lead to better acceptance by lactase‐deficient consumers. Moreover, the sensory characteristics of the cheese remained unchanged during the whole cold storage period, ensuring an extended shelf life.

Protective effect of reuterin-producing Lactobacillus reuteri against Listeria monocytogenes and Escherichia coli O157:H7 in semi-hard cheese

Bioprotective effect of reuterin-producing Lactobacillus reuteri INIA P572 was assessed in cheeses artificially contaminated with Listeria monocytogenes and Escherichia coli O157:H7 and ripened for 30 days. Reuterin production in cheese made with L. reuteri INIA P572 supplemented with 100 mM glycerol was confirmed up to 7 d of ripening with a maximum of 5.2 μmol/g at 1 day. L. reuteri was able to survive up to 5.37 log cfu/g in 30 d control cheese, although it was reduced to 2.59 log cfu/g when added simultaneously with glycerol. L. monocytogenes counts in control cheese were 4.31 log cfu/g after 30 days of ripening, whereas in cheese made with L. reuteri INIA P572 and 100 mM glycerol, this pathogen was only detectable by enrichment of 25 g samples from day 7 onwards. This antimicrobial strategy also diminished E. coli O157:H7 counts on day 1 by 5.53 log units with respect to control cheese. After 30 d, E. coli O157:H7 counts were 0.85 log cfu/g in control cheese, but the pathogen was not detected in 25 g cheese made with L. reuteri and 100 mM glycerol from day 7 onwards. Reuterin production in situ might be a feasible alternative to improve cheese safety that could also be exploited in the control of other undesirable microorganisms.