Milk Cheese Research Articles

Occurrence and diversity of Shiga toxin-producing Escherichia coli (STEC) in Italian Alpine raw milk cheeses and their development in the earlier stages of different cheese-making processes

Shiga toxin-producing Escherichia coli (STEC) are foodborne pathogens implicated in diseases including hemorrhagic colitis and hemolytic uremic syndrome. In the last years, an increasing number of STEC infections associated with the consumption of raw milk cheeses have been reported, contributing to raise the public awareness. The aim of this study was to assess the occurrence of STEC biotypes in raw milk cheeses from Italian Alpine region and evaluate the influence of different scalding temperatures on their development. Six out 82 (7.3%) cheeses led to the isolation of E. coli biotypes with different virulence traits (stx1, stx2 and eae genes). To evaluate the impact of scalding temperatures on STEC growth, three E. coli biotypes were spiked into milk (< 50 CFU/mL) according to the FAO and WHO recommendation. An increase in STEC counts of 3 log occurred in uncooked and semi-cooked cheeses (scalding temperature of 38 and 45 °C) while in the cooked-cheeses (54 and 56 °C) E. coli content does not exceed the 2.5 log10 CFU/g. These findings showed that raw milk cheese safety is strictly related to their production technology, highlighting the importance of the control measures at farm and dairy level to preserve the safety of these products.

Determining the influence of raw milk β-casein polymorphism on the efficiency of making soft cheese

One of the ways to increase the profitability of the cheese industry is the genetic selection of dairy cows to obtain milk with excellent cheese-capacity characteristics. The object of this study is the technology of fresh soft cheeses made by the acid-rennet and thermo-acid method from the milk of cows with different β-casein genotypes (A1A1, A1A2, A2A2). The subjects of research are the physicochemical indicators of raw milk from cows with different genotypes for β-casein (A1A1, A1A2, A2A2); as well as the yield of soft cheeses. The study has established that the physicochemical parameters of milk from cows with different β-casein genotypes are typical for fresh cow's milk. The study showed that with the acid-rennet method, the composition of cheeses from A1A1 milk was 51.60 %, 21.63 %, and 23.62 % of moisture, protein, and fat, respectively. A1A2 milk cheeses contained 50.70 % moisture, 20.96 % protein, and 25.12 % fat. A2A2 milk cheeses consisted of 52.50 % moisture, 20.70 % protein, and 23.71 % fat. With the thermo-acid method, cheeses from A1A1 milk were characterized by the moisture content of 55.13 %, proteins – 23.31 %, and fat – 20.21 %. A1A2 milk cheeses contained 58.13 %, 22.62 %, and 17.98 % of moisture, protein, and fat, respectively. A2A2 milk cheeses consisted of 54.03 % moisture, 22.33 % protein, and 22.25 % fat. The calculation of the production efficiency of soft cheeses from the milk of cows with different genotypes according to β-casein with the acid-rennet method of production is 119.3 % on average, which is more compared to milk A1A2 (by 4 %) and A2A2 (by 7 %). With the thermo-acidic method, the efficiency of cheese production from A2A2 milk is 107.5 %, which is higher compared to A1A2 milk (by 9 %) and A1A1 (by 5 %). The conclusions show that changes in the β-casein genotype in raw milk can affect the yield and quality of cheese, and therefore, the profitability of production

Protein fractionation by microfiltration of goat milk: Influence on proteolysis, metabolites and sensory characteristics of cheeses produced throughout lactation

This study addresses seasonal variations in goat milk by examining the effects of microfiltration (MF) and micro- and diafiltration (MDF) in standardising goat milk composition for cheese production. The research focuses on MF and MDF treatments at two lactation stages, analysing their impact on the quality of a hard goat milk cheese. Key parameters such as total solids, pH, organic acids, free amino acids, protein profiles, and sensory properties during cheese ripening were evaluated. Sensory attributes were assessed using Quantitative Descriptive Analysis (QDA), revealing different profiles between treatments. The MF cheeses showed a balanced profile, while MDF cheeses varied more in sourness, acidity, and texture, also influenced by lactation stage.

Analysis of the zoonotic tick-borne encephalitis virus (TBEV) in raw milk and dairy products in mountain pastures of the Lombardy region, Italy.

Over the last few decades, tick-borne encephalitis (TBE) has become a growing public health problem in Europe. The tick-borne encephalitis virus (TBEV) is a zoonotic virus that affects the central nervous system (CNS). TBEV has been detected in 27 European countries, and the rise in TBE cases is mainly due to environmental and ecological factors, and factors that increase the risk of human exposure to infected ticks. The infection via the alimentary route is the second most common means of TBEV transmission to humans. Raw milk from infected goats, sheep, or cows has been identified as a source of human food-borne infections. This study aims to gather new information on the prevalence of tick-borne encephalitis virus (TBEV) in raw goat's and cow's milk and related raw products in the Lombard Alps (Italy). This is important due to the close proximity of Lombardy to the Triveneto region, where TBE is endemic, and southern Switzerland, where numerous TBEV-positive mammals have been found. Throughout 2023, a passive monitoring plan was implemented on samples delivered for TBEV analyses from the Alpine pastures. In total, 248 specimens including raw milk, raw milk cheese, and butter were tested. This is the first monitoring of food at risk of TBEV transmission in a non-endemic region with evidence of TBEV circulation. Despite testing a wide range of dairy products, no sample tested positive for RNA-TBEV by real-time RT-PCR. Preliminary results suggest that raw milk and raw dairy products do not pose a significant risk of TBEV transmission to humans in the territory of Lombardy.

Impact of preacidification on the functionality and insoluble calcium levels of Low-Moisture Part-Skim Mozzarella made from high-casein milk

The use of low-concentration factor ultrafiltered (LCF-UF) milk for cheesemaking has become popular in recent years. Research on using LCF-UF milk to make low-moisture part-skim (LMPS) Mozzarella manufacture is limited due to concerns about the negative impact of the higher casein content on functional properties, such as melt and stretch. Pre-acidification (PA) (reflects acid added to milk before the addition of the starter culture) has been used in low-fat and nonfat Mozzarella cheeses to lower calcium levels and improve their texture and melting properties. We explored the use of PA to reduce the insoluble calcium content of cheese (calcium that is a crosslinking material for the casein proteins) and its impact on the functionality of LMPS Mozzarella made from high casein (4.2%) milk. Seven vats of LMPS Mozzarella, with a control (no PA), 2 pH values for PA (6.40 and 6.00) and 3 different acidification methods (use of acetic, citric, or carbonic acid from carbon dioxide) were evaluated for their impact on solubilization of colloidal calcium phosphate during LMPS manufacture. Composition, proteolysis, microstructural and functional changes in the LMPS cheeses were monitored during 90 d of refrigerated storage. All cheeses had similar composition except for the cheese made with milk PA with carbonic acid, which had a lower fat-in-dry matter probably due to foaming observed in this sample during the gas sparging. The cheese made with milk PA with citric acid to pH 6.00 had the lowest amount of total and insoluble calcium compared with other cheeses at all steps during cheese manufacture and storage, likely due to the calcium chelating ability of citric acid. The cheese that was made with milk PA with citric acid to pH 6.40 had a trend of slightly lower (not significant) total and insoluble calcium during cheese manufacture compared with other cheeses that were made with milk PA to pH 6.40. The pH value in all the cheeses remained similar throughout 90 d of storage, whereas the cheese that was made with milk PA with citric acid to pH 6.00 had the lowest pH values during storage. Treatment significantly (P < 0.05) impacted instrumental hardness, the maximum loss tangent during heating, the melting temperature and the storage modulus values measured at 70°C. Proteolysis was not impacted by treatment suggesting that typical aging should occur. Cheese that was PA with citric acid to pH 6.00 initially had lower maximum loss tangent values and higher hardness, possibly due to the lower pH value of this cheese. The performance of cheeses on pizza was assessed using Sensory Spectrum® method and quantitative descriptive analysis. The PA of cheese milk with citric acid helped to reduce the insoluble Ca level and at 30 and 90 d of storage, these cheeses had lower first chew hardness, lower chewiness, and lower strand thickness values compared with other cheeses. The use of PA could help improve the functionality of LMPS Mozzarella made from milk high in casein with citric acid being the most efficient in dissolving the insoluble calcium from casein.

Proximate and fatty acid analysis of goat and goat-cow mixed milk cheeses

Proximate and fatty acid analysis of goat and goat-cow mixed milk cheeses

Study on the Inhibitory Effect of Bioactive Peptides Derived from Yak Milk Cheese on Cholesterol Esterase.

The bioactive peptides derived from yak milk cheese exhibited cholesterol-lowering properties. However, there was limited research on their inhibitory effects on cholesterol esterase (CE) and elucidation of their potential inhibitory mechanisms. In this study, we identified CE-inhibiting peptides through virtual screening and in vitro assays. Additionally, molecular docking and molecular dynamics studies were conducted to explore the mechanisms. The results indicated that peptides RK7 (RPKHPIK), KQ7 (KVLPVPQ), QP13 (QEPVLGPVRGPFP), TL9 (TPVVVPPFL), VN10 (VYPFPGPIPN), LQ10 (LPPTVMFPPQ), and SN12 (SLVYPFPGPIPN) possessed molecular weights of less than 1.5 kDa and a high proportion of hydrophobic amino acids, demonstrating notable inhibitory effects on CE. Molecular docking and dynamics revealed that peptides RK7, KQ7, QP13, and VN10 bound to key amino acid residues Arg423, His435, and Ser422 of CE through hydrogen bonds, hydrophobic interactions, salt bridges, and π-π stacking, occupying the substrate-binding site and exerting inhibitory effects on CE. The four peptides were further synthesized to verify their CE-inhibitory effects in vitro. RK7, KQ7, QP13, and VN10 exhibited inhibitory activity on CE with IC50 values of 8.16 × 10-7 mol/L, 8.10 × 10-7 mol/L, 4.63 × 10-7 mol/L, and 7.97 × 10-7 mol/L; RK7, KQ7, QP13, and VN10 were effective in inhibiting CE after simulated gastrointestinal digestion, especially with a significant increase in the inhibitory activity of KQ7 and RK7, respectively. Our findings suggested that bioactive peptides from yak milk cheese represented a novel class of potential CE inhibitors.

Investigation of physico-chemical and microbiological parameters of traditional mongolian cheese

The traditional technology of Mongolian cheese is almost the same in different parts of the country, it differs from other types of cheeses, there is no microbiological process in it. Within the framework of this study, physico-chemical and microbiological parameters were determined in order to assess the quality and safety of Mongolian cheese sold on the market in Ulanbaatar. The article is devoted to the traditional Mongolian cheese, which belongs to the group of fresh fermented milk cheeses produced by thermal acid coagulation of milk. The main stages of its production include pasteurization of milk, coagulation, molding and pressing of cheese mass. Unlike other types of cheese, the production process of Mongolian cheese does not include clot processing, salting and maturation, which limits its shelf life. However, this cheese is an important source of casein and whey proteins for the Mongolian population. The method of cheese production is based on thermic acid coagulation, which uses high temperature. Mongolian cheese, like other cheeses of this group, is absorbed by the body by 96-98%, being an important source of calcium, phosphorus and amino acids. Milk proteins in such cheeses are not decomposed by microorganisms, which reduces the content of soluble proteins. Studies of the microflora of Mongolian cheese have shown the presence of various microorganisms, mainly lactic acid bacteria, and the absence of pathogenic bacteria when properly stored. The addition of preservatives such as nisin and natamycin can extend the shelf life of cheese up to 15 days.

From raw milk cheese to the gut: investigating the colonization strategies of Bifidobacterium mongoliense.

The microbial ecology of raw milk cheeses is determined by bacteria originating from milk and milk-producing animals. Recently, it has been shown that members of the Bifidobacterium mongoliense species may become transmitted along the Parmigiano Reggiano cheese production chain and ultimately may colonize the consumer intestine. However, there is a lack of knowledge regarding the molecular mechanisms that mediate the interaction between B. mongoliense and the human gut. Based on 128 raw milk cheeses collected from different Italian regions, we isolated and characterized 10 B. mongoliense strains. Comparative genomics allowed us to unveil the presence of enzymes required for the degradation of sialylated host-glycans in B. mongoliense, corroborating the appreciable growth on de Man-Rogosa-Sharpe (MRS) medium supplemented with 3'-sialyllactose (3'-SL) or 6'-sialyllactose (6'-SL). The B. mongoliense BMONG18 was chosen, due to its superior ability to utilize 3'-SL and mucin as representative strain, to investigate its behavior when co-inoculated with other bifidobacterial species. Conversely, members of other bifidobacterial species did not appear to benefit from the presence of BMONG18, highlighting a competitive scenario for nutrient acquisition. Transcriptomic data of BMONG18 reveal no significant differences in gene expression when cultivated in a gut simulating medium (GSM), regardless of whether cheese was included or not. Furthermore, BMONG18 was shown to exhibit high adhesion capabilities to HT29-MTX human cells, in line with its colonization ability of a human host.IMPORTANCEFermented foods are nourishments produced through controlled microbial growth that play an essential role in worldwide human nutrition. Research interest in fermented foods has increased since the 80s, driven by growing awareness of their potential health benefits beyond mere nutritional content. Bifidobacterium mongoliense, previously identified throughout the production process of Parmigiano Reggiano cheese, was found to be capable of establishing itself in the intestines of its consumers. Our study underscores molecular mechanisms through which this bifidobacterial species, derived from food, interacts with the host and other gut microbiota members.

Optimisation of soft camel cheese production coagulated with green carob extract using response surface methodology: Yield, physicochemical, microbial, sensorial, and rheological properties

This study addresses the processing limitations of camel milk for production of textured camel milk cheese by utilising the green carob extract (GCE) as a novel coagulant. The response surface methodology was employed to assess the impact of GCE on the cheese quality parameters. Maximal soft camel cheese yield (24.1%) was achieved using 12% (v/v) of GCE, coagulation at 53.6°C, and incubation time of 9 h 52 min. Compositional analysis revealed the richness of soft camel cheese in dry matter (33.8 ± 81.61%), carbohydrates (3.66 ± 0.45%), and calcium (632.83 ± 68.43 mg/100 g). The addition of GCE enhanced the cheese's flavour and texture.

Experimental Studies on the Siirt Herby Tulum Cheese: II. Evaluation of a New Industrial Process Model

This study was conducted to test a process that we had previously developed in parallel to the traditional Siirt Herby Cheese production method. Both raw and pasteurized Eve's milk were used parallelly in the study. Pasteurized milk was inoculated with an autochthonous starter culture which we have developed. After clot formation, breaking the clot, straining and acidification of curd by using acid whey, first pressing, adding herb and salt, and applying the second pressing stages were followed. Then, the cheese samples were packaged. No air gap was presented in the cheese containers. The entire production was completed within 24 hours. During the 120-d ripening period of the samples at 4 °C, pH was observed to be 5 and acidity was 0.7% (lactic acid). In raw milk cheese, pH was 6.8 and acidity was 1.12% at the end of the ripening period. It was determined that the method tested in this study was not recommendable for making raw milk cheese. The pasteurized milk cheese samples had at least 0.7 acidity, 5 pH, 20% fat and 20% protein; It was observed that at least 45% dry matter values could be obtained. However, the pasteurized milk cheese samples did not fully meet our expectations. The crumbling property of the cheese samples was not ideal just seen in the tradiditonal Tulum Cheeses of Türkiye. The slightly sticky and melted appearance was considered a negative property of the cheese and should be eliminated with more detailed work. Traditional production takes at least 10 d. This period may be long for industrial production. Raw milk is used in traditional production, and excessive salt is added to the cheese for hygiene purposes. Also, it is not easy to make a standard production. More research is needed to eliminate such negativities, and to recommend a valuable industrial process.

Cheddar cheese production, structure and in-vitro semi-dynamic gastric digestion: The role of β-casein phenotype

The objective of this study was to establish the impact of β-casein A1/A1, A1/A2 and A2/A2 phenotypes on the cheese-making process, cheese structure and on the subsequent in vitro gastric digestion properties of the cheese samples. The time required for curd cutting in cheese milk containing β-casein A2/A2 was significantly delayed, compared to milks containing β-caseins A1/A1 and A1/A2. After 180 days of ripening no differences were observed in the level of soluble nitrogen at pH 4.6 between any of the cheese samples, with a decrease in the level of aggregated β-sheets and increase in the level of β-turns and random coils observed in all cheese over the ripening period. During simulated gastric digestion, cheese samples took between 15 and 20 min to form the initial digesta coagulum, which occurred between pH 4.3 and 4.0. The rate of protein breakdown was slower in A2/A2 cheese, with less cheese structure degradation occurring, compared to β-casein A1 containing cheeses. This study has shown that rennet coagulation takes significantly longer in cheese milk containing only β-casein A2/A2, and that there was less protein breakdown during its simulated gastric digestion.

Bioconservation of hard rent cheese using bacteriophages

Several technological approaches are used to increase the safety of perishable food products during their production and realization. In particular, it is the use of temperature, high pressure, ultraviolet radiation and added preservatives. One of the generally recognized and common disadvantages of all these methods is that they have an influence on the microorganisms indiscriminately, that is, they inhibit both pathogenic and potentially beneficial autochthonous lactic acid bacteria of the "normal" microflora of fermented products. The purpose of this investigation was to monitor hard rennet cheeses for the content of Staphylococcus aureus and to develop a technology for its preservation using a lytic staphylococcal bacteriophage. Contamination of milk-raw material and Dutch cheese with Staphylococcus aureus was determined by inoculating the selected samples and carrying out tenfold dilutions on a selective hemoagar medium with 5% sodium chloride, followed by thermostating for +37-48 hours. Isolation of bacteriophages from milk raw materials was carried out by filtering through bacterial filters with pores of 0.45 μm. During the improvement of the technology of Dutch cheese with staphylococcal bacteriophage, two samples of cheese were produced - one experimental with bacteriophage, and the second control - without bacteriophage. It was set up that in milk-raw material, which is processed for the production of hard cheeses, Staphylococcus aureus was not detected in 25 to 40% of the samples, on average 45% of the milk samples were contaminated with this pathogen up to 5×102 CFU/ml and from 18 to 30% samples had a staphylococci content of more than 5×102 CFU/ml. In hard cheeses which are realized in the retail network, Staphylococcus aureus was not isolated in an average of 25% of the samples, while approximately 30% of the samples were contaminated with this microorganism in the amount of more than 5×102 CFU/g, which exceeds the requirements of the standard. Two bacteriophages were selected that showed 75.0-80.0% lytic activity against cultures of Staphylococcus aureus from milk and hard cheeses. These bacteriophages were used in the technology of preserving hard Dutch cheese. The technology of Dutch cheese with staphylococcal bacteriophage has been developed to increase its safety during implementation. The use of lytic bacteriophages for the biocontrol of Staphylococcus aureus in rennet cheese makes it possible to almost completely neutralize them in the technology of production. Therefore, the use of lytic bacteriophages to increase the safety of dairy products is an environmentally clean way of restraining the development of pathogenic bacteria, thereby not influencing on the fermentation microflora of the product.

Epidemiology, Virulence and Antimicrobial Resistance of Escherichia coli Isolated from Small Brazilian Farms Producers of Raw Milk Fresh Cheese.

This study aimed to identify contamination sources in raw milk and cheese on small farms in Brazil by isolating Escherichia coli at various stages of milk production and cheese manufacturing. The study targeted EAEC, EIEC, ETEC, EPEC, STEC, and ExPEC pathotypes, characterizing isolates for the presence of virulence genes, phylogroups, antimicrobial susceptibility, and phylogenetic relationships using PFGE and MLST. The presence of antimicrobial resistance genes and serogroups was also determined. Three categories of E. coli were identified: pathogenic, commensal, and ceftriaxone-resistant (ESBL) strains. Pathogenic EPEC, STEC, and ExPEC isolates were detected in milk and cheese samples. Most isolates belonged to phylogroups A and B1 and were resistant to antimicrobials such as nalidixic acid, ampicillin, kanamycin, streptomycin, sulfisoxazole, and tetracycline. Genetic analysis revealed that E. coli with identical virulence genes were present at different stages within the same farm. The most frequently identified serogroup was O18, and MLST identified ST131 associated with pathogenic isolates. The study concluded that E. coli was present at multiple points in milk collection and cheese production, with significant phylogroups and high antimicrobial resistance. These findings highlight the public health risk posed by contamination in raw milk and fresh cheese, emphasizing the need to adopt hygienic practices to control these microorganisms.

Evaluating Source Complexity in Blended Milk Cheese: Integrated Strontium Isotope and Multi-Elemental Approach to PDO Graviera Naxos.

Graviera Naxos, a renowned cheese with Protected Designation of Origin status, is crafted from a blend of cow, goat, and sheep milk. This study focused on assessing the Sr isotopic and multi-elemental composition of both the processed cheese and its ingredients, as well as the environmental context of Naxos Island, including samples of milk, water, soil, and feed. The objective was to delineate the geochemical signature of Graviera Naxos cheese and to explore the utility of Sr isotopes as indicators of geographic origin. The 87Sr/86Sr values for Graviera Naxos samples ranged from 0.70891 to 0.70952, indicating a relatively narrow range. However, the Sr isotopic signature of milk, heavily influenced by the feed, which originates from geologically distinct areas, does not always accurately reflect the local breeding environment. Multi-elemental analysis revealed variations in milk composition based on type and season; yet, no notable differences were found between raw and pasteurized milk. A mixing model evaluating the contributions of milk, sea salt, and rennet to the cheese's Sr isotopic signature suggested a significant average contribution of 73.1% from sea salt. This study highlights the complexities of linking dairy products with their geographical origins and emphasizes the need for sophisticated geochemical authentication methods.

Chemometric characterization of the fatty acid and trace element profiles of organic and conventional Galician cheeses

The aim of this study was to evaluate the fatty acid profile and trace element content in three different Galician cow's milk cheeses (organic made from pasteurized milk, industrial made from pasteurized milk and artisanal made with raw milk). Twenty-five fatty acids and thirteen elements were determined by respectively gas liquid chromatography and inductively coupled plasma mass spectrometry, in thirty representative samples of the cheeses. The organic cheeses had significantly lower palmitic acid contents and significantly higher contents of odd and branched fatty acids, oleic acid, vaccenic acid, α-linolenic acid and conjugated linoleic acid than the other cheeses. The organic cheeses also had lower concentrations of trace and toxic element residues. Moreover, an association between medium chain fatty acids and palmitic acid and the presence of several mineral elements was detected by chemometric techniques. The nutritional evaluation of the organic cheeses was more favorable than for the other cheeses, as confirmed by the values of health-related indices.

Prospective life cycle assessment of an integrated biorefinery for production of lactic acid from dairy side streams

In Ireland, the world's first-of-a-kind integrated dairy biorefinery has been developed to address waste disposal challenges in the dairy industry by converting dairy side streams into high-value biochemicals, specifically lactic acid (LA). This study aims to assess the environmental impacts of this innovative technology at a commercial scale through a comprehensive life cycle assessment (LCA) study. Experimental data from a pilot-plant facility was scaled up to a production capacity of 20,000 tons of LA per year using SuperPro Designer®. This data was combined with information from upstream processes such as milk production, cheese production, and transport, using OpenLCA. The cradle-to-gate LCA revealed that milk production had the greatest overall impact across all categories. Enteric fermentation has the most significant impact on climate change, while fertilizer and concentrate feed production primarily contributed to non-renewable energy demand, ozone formation, human toxicity, water consumption and fossil depletion. Fertilizer application substantially influenced eutrophication, acidification and ecotoxicity indicators. However, scenario analysis showed that implementing strategies like substituting biorefinery byproducts with fossil-based products, increasing renewable energy penetration, and integrating dairy beef production could result in significant environmental savings across all impact categories. Moreover, the findings highlighted that the handling of co-products would determine the magnitude of the system's impact. This study concludes that combining process design analysis with accessible data at a higher Technology readiness level (TRL) 7 offers an opportunity to identify hotspots and recommend alternative strategies to improve the environmental sustainability of the whole system at the design stage. Additionally, this study provides valuable guidance for minimizing environmental impacts during the design phase, enabling informed investment decisions before construction. Ultimately, it plays a crucial role in establishing a circular bioeconomy within the dairy industry by effectively utilizing the side streams to produce sustainable biobased chemicals, specifically LA.

Development of a cell culture-based method for detecting infectious tick-borne encephalitis virus (TBEV) in milk products

Tick-borne encephalitis outbreaks have been reported in Europe after consumption of raw milk products from infected animals. While molecular methods are commonly used in viral foodborne outbreak investigations due to their sensitivity, specificity and rapidity, there are very few methods to detect infectious tick-borne encephalitis virus (TBEV) in milk products for routine use/analyses. To address this gap, we developed a cell culture-based method to detect infectious TBEV in artificially contaminated raw goat milk and raw goat cheese, and evaluated the sensitivity of TBEV infectivity assays. Raw goat milk samples were spiked with TBEV to achieve inoculation levels ranging from 106 to 100 TCID50/mL, and Faisselle and Tomme cheese samples were spiked so their TBEV concentrations ranged from 9.28 × 105 to 9.28 × 101 TCID50 per 2.5g. To detect infectious TBEV, Vero cells were infected by raw goat milk. For cheese samples, after homogenisation and membrane filtration, Vero cells were infected with samples adsorbed on the filter (method A) or with samples eluted from the filter (method B). After 5 days, cytopathic effects (CPEs) were observed and TBEV replication in Vero cells was confirmed by an increase in the number of genome copies/mL that were detected in cell supernatant. Infected Vero cells exhibited CPEs for both milk and cheese samples. Infectious TBEV was detected to 103 TCID50/mL in raw milk samples and to 9.28 × 101 TCID50 from Faisselle samples using both methods A and B. For Tomme samples, method A was able to detect TBEV to 9.28 × 102 TCID50/2.5g and method B to 9.28 × 103 TCID50/2.5g. The number of positive samples detected was slightly higher with method A than with method B. To conclude, this qualitative cell culture-based method can detect infectious TBEV artificially inoculated into raw milk and cheese; it should be further evaluated during foodborne outbreak investigations to detect infectious TBEV from naturally contaminated milk and cheese.

A hurdle strategy based on the combination of non-thermal treatments to control diarrheagenic E. coli in cheese

This study aimed to assess the efficacy of a multi-hurdle process combining mild High Hydrostatic Pressure (HHP) treatments and Thyme Oil (TO) edible films as a non-thermal method to combat pathogenic E. coli (aEPEC and STEC) in raw cow's-milk cheese stored at 7 °C and packaged under modified atmosphere. Changes in headspace atmosphere of cheese packs and treatment effects on Lactic Acid Bacteria (LAB) counts and diarrheagenic E. coli strains (aEPEC and STEC) were evaluated over a 28 d storage period. The results demonstrated that the combined treatment exhibited the most significant antimicrobial effect against both strains compared to individual treatments, achieving reductions of 4.30 and 4.80 log cfu/g after 28 d of storage for aEPEC and STEC, respectively. Notably, the synergistic effect of the combination treatment resulted in the complete inactivation of intact cells for STEC and nearly completed inactivation for aEPEC by the end of the storage period. These findings suggest that the combination of HHP with selected hurdles could effectively enhance microbial inactivation capacity, offering promising alternatives for improving cheese safety without affecting the starter microbiota.

Utilization of retentates for white brined cheese production: comparative evaluation of physico-chemical and sensory properties

The aim of the present study is (1) to enhance the protein fraction in cheese milk through membrane filtration and consequently (2) to separate the majority of whey as ‘ideal whey’ prior to the production of white brined cheese, and (3) to explore the potential utilization of retentates in the production of white brined cheese. The chemical, physical, textural and sensory properties of cheeses produced from microfiltration (MF) retentates were characterized to investigate the effects of cross-flow MF on white brined cheese. Polyether sulfone (MP005) membranes featuring a pore diameter of 0.05 μm and polyvinylidene fluoride (MV020) membranes with a pore diameter of 0.20 μm were utilized. The assessed quality parameters of cheeses derived from polyethersulfone membrane (MP005) retentates were similar to the control (p > 0.05), whereas the cheese obtained from polyvinylidene fluoride membrane (MV020) retentates exhibited notable differences (p < 0.05) from the control. The traditional whey generated after cheese-making, which typically requires substantial on-site processing and/or treatment, was reduced by 3.5–6.7 times using the MP005 retentates. Simultaneously, 58–70% of the cheese milk (w/w) was separated as ideal whey before the cheese-making process. MF shows potential as an eco-friendly technology suitable for use in cheese production processes. The potential utilization of MP005 for enriching the protein content in cheese milk holds promise for white cheese production.