Types Of Cheese Research Articles

A Pre-Trial Study to Identify Species of Origin in Halloumi Cheese Utilising Chemometrics with Near-Infrared and Hyperspectral Imaging Technologies

Halloumi cheese has recently gained a Protected Designation of Origin (PDO) indicator, which is related to the place (Cyprus) in which halloumi cheese is made. The PDO label is linked with several requirements, e.g., milk species, quantities, etc.; thus, it is important to study this product regarding authenticity. The utility of using two spectroscopic techniques, hyperspectral imaging (HSI) (400–1000 nm) and conventional near-infrared spectroscopy (NIR) (800–2500 nm) were assessed for the discrimination of 17 Cypriot halloumi cheese types, which could be categorized as of cow or goat–sheep origin. The aim of this study was to obtain spectral information for halloumi cheese using other promising infrared and imaging spectroscopic techniques as a comparison to a previously acquired mid-infrared (MIR) spectroscopy dataset. NIR and HSI are both fast and easy techniques in application, both of which provide significant information in food analysis. Chemometric analysis was crucial for interpreting the spectroscopic data by applying the unsupervised methods: principal component analysis (PCA) and hierarchical cluster analysis (HCA). The HSI model was found to be based intuitively on the appearance of cheese samples after freeze-drying (e.g., color; yellow/white, and texture; oily/dry), while the NIR grouping of samples was determined to be based on composition, mainly fat, protein and lactose content of the cheese samples. The HSI model returned distinct clusters of the two halloumi cheese types, cow and goat–sheep origin, with one outlier (16/17 accuracy; 94%), while the NIR model proved less accurate (13/17; 76%).

Comparison between antibacterial effect of nanoparticles and non-nanoparticles of chitosan on Listeria monocytogenes isolated from different types of Egyptian cheese

The objectives of this paper were to investigate the existence of Listeria monocytogenes (L. monocytogenes) in different types of cheese (Mozzarella, Thalaga, and Romy cheeses, 40 samples each) sold in Assiut dairy shops and to evalute antibacterial properties of chitosan and its nanoparticles against isolated strains. L. monocytogenes was isolated in higher percentage from Mozzarella cheese (25%) followed by Thalaga and Romy cheese samples. L. monocytogenes isolates were validated by PCR utilising the 16S rRNA gene. Zeta-sizer and TEM were used to characterise nano-chitosan. The minimum inhibitory concentrations of chitosan and nano-chitosan on L. monocytogenes were detected by MIC test. Nano-chitosan (3.125%) could prevent organism growth in cheese as early as the third week. The findings revealed that 3.125% nano-chitosan had a sufficient effect on L. monocytogenes while also providing good consumer satisfaction; therefore, nano-chitosan should be utilised as a natural food additive in Egyptian dairy products.

Chemometrics-driven monitoring of cheese ripening: a multimodal spectroscopic and scanning electron microscopy investigation.

The integration of spectroscopic techniques with chemometrics offers a means to monitor quality changes in dairy products throughout processing and storage. This study employed Attenuated Total Reflectance-Mid-Infrared Spectroscopy (ATR-MIR) coupled with Independent Components Analysis (ICA), and 3D Front-Face Fluorescence Spectroscopy (FFFS) paired with Common Components and Specific Weight Analysis (CCSWA). The research focused on Cheddar cheeses aged for 1, 2, 3, and 5 years, alongside Comté cheeses aged for 6, 9, and 12 months. The adopted approach offered valuable insights into the intricate cheese aging process within the food matrix. The ICA proportions and CCSWA scores highlighted the significant impact of biochemical transformations during maturation on the aging process. The extracted independent components (ICs) revealed variations in the vibration modes of amides, lipids, amino acids, and organic acids, facilitating the distinction between different cheese age categories. Additionally, CCSWA outcomes identified age-related differences through shifts in tryptophan fluorescence characteristics as the cheeses aged. These results were consistent with the observed alterations in the microstructure of cheese samples over time, corroborated by Scanning Electron Microscopy (SEM) imagery. The introduced multimodal methodology serves as a significant asset for determining the ripening stage of various types of cheese, offering a detailed perspective of cheese maturation beneficial to the dairy industry and researchers.

Assessment of some chemical residues in Egyptian raw milk and traditional cheese.

The assessment of risks related to food safety is becoming a challenge in developing countries with its consequent health hazards. Chemical risk assessment in dairy products is important to maintain consumer health locally and internationally. Since milk and dairy products are essential foods for a wide range of customers, mostly children, patients, and pregnant women, it is very important to estimate the risks of some chemical residues, such as pesticides, some heavy metals, and aflatoxins. This work aims to determine the levels of chemical contamination in milk and traditional Egyptian cheese. Heavy metals were determined in samples by atomic absorption spectrometry. GC-mass spectrometry (MS)/MS and LC-MS/MS were also used for measuring pesticide residues. The Aflatoxin M1 was determined by enzyme-linked immune-sorbent assay. Raw milk samples were tested and showed elevated concentrations of lead and cadmium, (46% and 4%, respectively). The heavy metals detected in the Egyptian cheese samples were variable depending on the type of cheese. Moreover, p.p.-DDE phenofose was present in 45% and 29% of raw milk and Ras cheese samples, respectively. For Aflatoxin M1, only 7% of milk samples and 2.9% of Ras cheese samples exceeded the acceptable limits. More surveying and risk assessment of chemical residues in milk and milk products are essential for controlling health risks to consumers.

Characterization of the key flavor compounds in cream cheese by GC-MS, GC-IMS, sensory analysis and multivariable statistics

The aroma types of cream cheese affect its commercial value and consumer acceptability. However, the types of volatile substances and sensory characteristics of cream cheese at different fermentation stages are still unclear. Therefore, in this study, headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS) were used to analyze the volatile substances in cream cheese fermentation. Orthogonal partial least squares discriminant analysis (OPLS-DA), odor activity value (OAV), relative odor activity value (ROAV) and variable projection importance (VIP) were used to identify the characteristic flavor substances in cream cheese fermentation. Finally, the relationship between key flavor substances and sensory characteristics was determined by partial least squares (PLS) analysis. A total of 34 and 36 volatile organic compounds were identified by HS-SPME-GC-MS and HS-GC-MS, respectively, and 14 characteristic flavor substances were found, based on VIP, ROAV and OAV models. Combined with sensory analysis and flavor substance changes, it was found that the cream cheese fermented for 15 d had the best flavor and taste. This study reveals the characteristics and contribution of volatile substances in cream cheese at different fermentation stages, which provides new insights into improving flavor and quality control.

Development of camel milk cheese technology and research of qualitative characteristics

Recently, interest in the production of camel milk and products from it has increased due to its nutritional and medicinal properties, including camel milk cheeses.In this study, the technology of cheese from non-pasteurized camel milk using mesophilic and thermophilic starter cultures was developed. The composition of camel milk and its microbiological safety indicators were studied. Next, three experimental types of camel milk cheese were prepared, where the physico-chemical composition, cheese yield, mineral composition and organoleptic parameters were determined. Thus, the content of the mass fraction of fat in the studied samples ranged from 25.45 to 22.13%. The mass fraction of solids for all samples was in the range of 50.50-62.30%; ash content was 3.05-3.65%; and the mass fraction of proteins was 17.49, 22.19%, respectively, in the control sample, cheese using mesophilic and thermophilic starter cultures. The cheese yield ranged from 115.20g/l to 137.98 g/l. The mineral composition of camel milk cheese showed that macronutrients such as Na, Mg, Ca, K, P. predominate in all samples. Also, all experimental samples of camel milk cheese had high organoleptic characteristics.

Влияние белкового концентрата на качественные показатели козьих сыров

Purpose. To determine the effect of sunflower protein concentrate on the amino acid composition of cheeses made on the basis of goat's milk. Materials and Methods. In the conditions of the complex analytical laboratory of VRIMMP, 3 samples of semi-hard cheese were produced, one of which was a control without additives and 2 – experimental (No. 1 and No. 2) with a percentage of protein concentrate of 1.0 and 2.5% of the total weight of the cheese. Cheese samples were produced using traditional technology in accordance with GOST R 52686-2006. The active acidity of the samples was monitored using a portable pH meter testo 206-pH2 with the function of determining pH and temperature. The protein content was studied using an analyzer based on the Kjeldahl method. Indicators of the mass fraction of fat were determined using glass butyrometers type 1-6 according to GOST 5867-90. The mass fraction of moisture was determined by drying the sample in calcined sand at a temperature of 103°C. Analysis of the amino acid composition of the finished samples was carried out on a Kapel 105M analyzer (Lumex LLC, St. Petersburg, Russia). Results. The protein content in cheese sample No. 1 is 1.4% higher than in the control, and the content of this indicator in sample No. 2 exceeds the control by 2.8%. The amino acid composition in the samples in which protein concentrate was introduced into the recipe exceeds the content of this indicator in the control sample, which indicates a beneficial effect of the introduced component on the nutritional value of the finished product. The moisture content in the experimental samples decreased compared to the control due to the introduction of the additive and an increase in dry matter: in sample No. 1 – by 1.42%, and in sample No. 2 – by 2.86%. A slight increase in fat was found in cheese samples No. 1 and No. 2, but the indicator was within the normal range, which corresponds to this type of product. Conclusion. The use of goat milk as a raw material for the production of various types of cheeses is a promising direction for dairy producers food products. Rich composition makes goat's milk an indispensable food product for both children and adults. Compared to the milk of other animals, goat's milk is easily digestible, has hypoallergenic properties, due to which it is in high demand among people watching their diet or suffering from various types of food allergies. The conducted research and obtained data indicate the prospect of using this type of raw material as a complete base, and the use of protein concentrate in the production formulation will allow to obtain an enriched product with increased protein content.

Cows’ and buffalo milk for cooked fresh cheese: preliminary comparison of the cheese-making efficiency and quality of griddled acid/heat-coagulated Paneer and rennet-coagulated Tosella/Schiz

Milk from cows and buffaloes represents the major source of dairy products worldwide. Cheese is consumed fresh, ripened, cooked, or as recipe ingredient in many different types. Using Paneer and Tosella/Schiz model cheeses as a case study of cooked cheeses, in this short communication we evaluated the cheese yield and quality of fresh cheese before and after cooking comparing the two major dairy species (cows and buffaloes). A total of 75 model cheeses (37 Paneer and 38 Tosella/Schiz) were made. Slices of all the cheeses were cooked on a griddle at 130 °C. Milk, whey, and cheese composition traits, cheese-making efficiency traits, and cooked cheese quality traits were evaluated using a mixed model that included the fixed effects of cheese type and animal species, and their interaction, and the random effects of session, animal within species, and the residual. Higher cheese yields are obtained from the buffalo milk not only because more concentrated in nutrients, but also for the greater recovery of nutrients in cheese. There was a greater recovery of protein with the acid/heat Paneer procedure than the rennet Tosella/Schiz procedure, but we found a species × cheese type interaction for fresh cheese yield. The interaction was related mainly to the higher water retained in the Tosella/Schiz curd rather than to total solids. This led also to greater cooking weight-loss compared with Paneer. The qualitative traits of cheese were highly affected by griddling. Future research on the sensorial perception of cooked cheeses from the two major dairy species is needed to predict consumer response.

PROCESSING OPTIMIZATION OF CRAFT CHEESE CAMEMBERT TYPE

The article substantiates the technology of craft cheese Camembert type with the use of goat milk and dried plant products for restaurants implementation. Differences in the biological value and technological properties of goat and cow milk were analyzed. It is shown that goat milk contains more protein, fat, lactose, potassium, calcium, magnesium and iodine in comparison to cow milk. The density of goat milk is about 1.033 g∕cm3, while for cow milk this indicator varies within 1.024 and 1.037 g∕cm3. Goat milk compared to cow milk contains more retinol, thiamine, ascorbic acid and less such an allergens as αs1-casein and α-lactoalbumin, that proofs an increased biological value of goat milk. Using the methods of experimental and statistical planning, a quadratic model was obtained that adequately describes the dependence of the cheese hardness parameter on the the milk fermentation temperature and the dosage of goat milk in the recipe of Camembert type cheese. As a result of the minimization of the cheese hardness parameter according to the obtained model, it was determined that the of goat milk should be added in the recipe of craft cheese Camembert type in an amount of 35.6% of cow milk content, and the fermentation of milk should be carried out at a temperature of 36°C. These parameters allow to obtain cheese with the hardness of 13.2%. A technological scheme for the production of craft cheese Camembert type was developed, that attaches mixing of goat milk and cow milk, fermentation of milk at a temperature of 36°C, as well as the addition of dried plant products, such as thyme, rosemary and tomatoes at the stage of a clot processing . Based on the results of the evaluation of the organoleptic quality indicators of the cheese, it was found that it has the correct shape, rich and balanced taste, as well as a soft and delicate consistency, which allows to recommend it for implementation into restaurants production.

Metabarcoding analysis reveals a differential bacterial community profile associated with ‘Torta del Casar’ and ‘Queso de la Serena’ PDO cheeses

A detailed understanding of the microbial ecology of artisanal cheeses is a crucial factor for implementation practices that can help to update their quality. In this study, the bacterial communities of Protected Designation of Origin (PDO) ‘Queso de la Serena’ and ‘Torta del Casar’ cheeses were characterised by 16S rRNA gene metabarcoding sequencing over 60 days of ripening at three dairies for each cheese variety. Both PDO cheeses presented a distinctive and unique bacterial community, suggesting that the manufacturing practices of each PDO shaped the microbiota. Lactococcus lactis and, to a lesser extent, Leuconostoc mesenteroides were the key lactic acid bacteria (LAB) species that drove the ripening process of PDO ‘Torta del Casar’, whereas in PDO ‘Queso de la Serena’, Leu. mesenteroides was the main LAB species, followed by Lactococcus raffinolactis and Lc. lactis, depending on the dairy. Furthermore, a wide range of non-starter LAB, Gram-negative bacteria and Gram-positive catalase-positive cocci were found, with a variable presence and abundance between dairies. In this regard, the dairy was a strong contributing factor to the variability in the composition of the bacterial community in each cheese type. In contrast, the impact of the ripening process was limited. Overall, this study enhances the understanding of the bacterial dynamics that occur during the ripening of these traditional PDO cheeses, highlighting the need to improve the standardisation of the raw materials and manufacturing practices to minimise inter-dairy variability, ensuring final quality and their unique sensory traits.

Influence of Salting and Ripening Conditions on the Characteristics of a Reduced-Fat, Semi-Hard, Sheep Milk Cheese.

This study aimed to assess the effect of salting and ripening conditions on the features of sheep milk, reduced-fat, semi-hard cheese. Eight groups of cheese, with an average fat content of ≅10.5%, moisture on non-fat substances (MNFS) ≅ 56%, a protein-to-fat ratio of 2.9 and pH 5.1, were manufactured and analyzed throughout ripening. The experimental factors were the salting method (brine- or dry-salting), the salt content (control- and reduced-salt) and the ripening temperature sequence (11 or 18 °C at the 3rd and 4th week). Brine-salted cheese exhibited significantly more adequate (p < 0.05) textural and organoleptic characteristics compared to its dry-salted counterpart, i.e., lower hardness, gumminess and adhesiveness, with higher lightness and flavor scores. The mean salt reduction from 2.1 to 1.6% exhibited significant effects (p < 0.05), i.e., increased moisture and MNFS, decreased hardness, gumminess, chewiness and adhesiveness, and increased lightness and meltability of cheese without affecting the microbiological stability or impairing the organoleptic parameters. Ripening at 18 °C at weeks 3-4 significantly increased (p < 0.05) proteolysis and concentrations of lactic and citric acid without affecting meltability, textural or organoleptic features. In conclusion, brine-salting, salt reduction by 20% and the elevation of temperature at a particular ripening period improved the characteristics of this type of reduced-fat sheep milk cheese.

Bottom-up proteomics to investigate the X-ray irradiation effects on soft cheese

Food irradiation is an alternative technological process employed to preserve the hygienic quality of food and to extend its shelf life. In this work, three different types of soft cheese, mozzarella, robiola and primosale, were treated with X-rays at 1.0, 2.0 and 3.0 kGy to evaluate their effect on proteins and peptides using a bottom-up proteomic approach. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-ToF-MS) and liquid chromatography coupled with MS through electrospray interface (LC-ESI-MS) were employed to analyse the peptide mixtures coming from the proteolytic digestion of soft cheese using both trypsin and chymotrypsin enzymes. We discovered 15 peptides most affected by X-rays that were sequenced by tandem MS and identified; ten of these discriminant peptides, generated from the cleavage of β-casein and α-casein (B. taurus), were localized on the proteins' secondary structure, highlighting a heightened susceptibility of random coils to X-ray irradiation. No additional post-translational modifications were found to be induced or emphasized by irradiation. For all studied cheese samples, the major spectral differences were encountered at 1.0 kGy, suggesting that such a dose was the most effective in promoting peptide bond cleavage. Some non-enzymatic and/or half-enzymatic peptides belonging to α-S1-, α-S2- and β-casein were also produced when varying X-ray doses.

Влияние термизации натуральных сыров на их функциональные свойства

The research featured the effect of thermal treatment on various types of natural cheeses and their functional properties, i.e., grating and shredding, melting, fat-release, browning, blistering, and elasticity. Natural and preheated samples underwent a point-scale assessment developed specifically for pizza cheeses by the All-Russian Scientific Research Institute of Butter- and Cheese-Making (Uglich, Russia). Thermal treatment improved the functional properties of natural cheese. In addition, preheated cheese proved to be a more effective and economical pizza ingredient.

Биотехнология производства мягких сыров из смеси коровьего и козьего молока с функциональными ингредиентами

The aim of this research is to develop a biotechnology of soft cheeses with func-tional ingredients based on a mixture of cow’s and goat’s milk taken in a ratio of 60:40, subjected to acoustic cavitation at 75 kHz and an exposure time of 17 min. To achieve the research aim, the tasks of selecting and determining the number of functional ingredients, determining the technological parameters of the production of soft cheeses with their use were solved. As a result, the biotechnology of two types of soft cheeses «Dieticheskij» and «Funkcionalnyj» has been developed. In the biotechnology of soft cheese «Dieticheskij», a complex preparation «Bivestin-lacto» containing cultures of probiotics Bifidobacterium longum MS-42, Lactoba-cillus plantarum 8PA-3 and dietary fiber «Citri-Fi» of medium grinding was used as a functional ingredient. Soft cheese «Funkcionalnyj» is enriched with a biocomponent containing probiotic cultures of Lactobacillus acidophilus La-5, Lactobacillus delbrueckii subsp. Bulgaricus, Bifidobacterium lactis, Streptococcus thermophilus, as well as «Selexen» – a source of selenium, «Curcumin» in micellar form and dietary fiber «Citri-Fi». Their organoleptic, chemical, microbiological parameters, as well as nutritional, energy value and shelf life have been determined.

Assessment of Rheological and Sensory Attributes of Queso Blanco Cheese Coated with Aloe Vera Gel

The study carried out to coat Queso Blanco cheese with Aloe Vera gel (AVG) and evaluate its physicochemical and sensory characteristics. The acid method was used to manufacture the cheese from skimmed milk (Al-Mudhish) QM1 and full-fat milk (Anchor) QA1 for control treatments. Whereas the cheese was coated with AVG for QM2 and QA2, respectively. An increase in the yield in QA1 (14.33 %) and QA2 (14.30%) in comparison to QM1 and QM2, which were 13.47 and 13.53%, respectively. Evaporation during the storage period was reduced in chess coating AVG. Consequently, the moisture content during the third week was 54.70 and 49.70% in QM2 and QA2, respectively, compared with 51.57 and 48.20% in QM1 and QA1, respectively. As a result, during the first week after manufacturing, the composition of the various coated cheese types remained relatively constant. Furthermore, after three weeks of storage, the AVG-coated QM2 and QA2 treatments had the highest evaluator acceptability, as they recorded 87.92, 86.15, respectively, compared with the control QM1, QA1, which were 74.23, 68.92 respectively. This specifies that coating the cheese with AVG assisted in maintaining its natural state during the storage period.

Compositional Characteristics, Fatty Acid Profile, Phenolic Content and Volatile Organic Compounds (VOCs) of Feta Cheese Made in Mountainous Grasslands and Plains of Greece

The study aimed to compare the physicochemical composition, fatty acid profile, phenolic content and volatile organic compounds (VOCs) of feta cheese produced in two regions in Greece (mountainous grasslands and plains). The VOC profiles of forage in the mountainous grasslands were also investigated in order to detect any relationship between the two profiles. Forbs were found to be the major functional group in the mountainous area and the most abundant VOCs were aldehydes, alcohols, and terpenes. Significant variations were observed between the main compositional features of the two types of cheeses, with the cheese produced from the milk of ewes and goats grazing in the mountainous region having a higher moisture content, lower fat content, and higher protein content. A total of 34 VOCs were identified and the most abundant groups in the cheese samples were esters, hydrocarbons, and alcohols. The fatty acid profile, phenolic content, and terpene profile of the cheese were also affected by the type of pasture. The cheese produced from the milk of ewes and goats grazing in the mountainous region also had a higher content of conjugated linoleic acid (CLA) and a lower content of saturated fatty acids (SFAs). These findings suggest that the grasslands grazed by ewes and goats in the mountainous region have a positive impact on the nutritional quality of feta cheese.

An Overview of the Occurrence of Bioactive Peptides in Different Types of Cheeses.

The search for improvements in quality of life has increasingly involved changes in the diet, especially the consumption of foods which, in addition to having good nutritional value, are characterized by offering health benefits. Among the molecules that trigger several beneficial responses are peptides, which are specific fragments of proteins known to produce positive effects on the human body. This review aimed to discuss the bioactive potential of peptides from cheeses. Studies show that the protein composition of some cheese varieties exhibits a potential for the release of bioactive peptides. The production of these peptides can be promoted by some technological procedures that affect the milk structure and constituents. The cheese maturation process stands out for producing bioactive peptides due to the action of enzymes produced by lactic acid bacteria. Thus, in addition to being proteins with high biological value due to their excellent amino acid profile, peptides from some types of cheeses are endowed with functional properties such as anti-hypertensive, antimicrobial, antioxidant, anticarcinogenic, opioid, and zinc-binding activities.

The Impact of Goat Milk Pretreatment with Pulsed Electric Fields on Cheese Quality.

To reduce the microbial load in goat's milk, which is less thermally stable than cow's milk, an alternative processing method was used in this study. This involved treating the milk with pulsed electric fields (PEFs) (at 10 kV·cm-1, with 50 µs pulses for 3 Hz) and then heat-treating it at 63 °C for 6.0 s, as well as using heat treatment alone at 75 °C for 3.4 s. Cheeses were made using both types of milk treatment, and samples were collected after 5, 15, and 25 days of ripening for DNA extraction and purification, followed by high-throughput sequencing on the MiSeq Illumina sequencing platform. Analysis of the bacterial populations in the two types of cheese using various diversity indices revealed no significant differences in species richness and abundance, although there was a trend for the PEF-treated cheese to have a less diverse set of species with an uneven distribution of relative abundance. However, when examining the composition of the microbial communities in the two types of cheese using Weighted UniFrac analysis and Analysis of Similarities, there were significant differences in the presence and abundance of various species, which could have implications for the development of starter cultures. Concerning physicochemical properties (pH, aw, moisture content, total acidity and L, and a and b color parameters), the results also reveal that, generally, no significant differences were found, except for the color parameter, where cheeses treated with PEF demonstrated more whiteness (L) and yellowness (b) during ripening. Sensory scores for typicity (caprylic, goaty, and acetic) increased over time, but between treatments, only small differences were perceived by panellists in cheese with 5 days of ripening. Concerning texture firmness and cohesiveness, the PEF+HT samples presented lower values than the HT samples, even over storage time. In general, concerning quality parameters, similar behavior was observed between the treatments during the ripening period.

Interrelationships among physical and chemical traits of cheese: Explanatory latent factors and clustering of 37 categories of cheeses

Cheese presents extensive variability in physical, chemical, and sensory characteristics according to the variety of processing methods and conditions used to create it. Relationships between the many characteristics of cheeses are known for single cheese types or by comparing a few of them, but not for a large number of cheese types. This case study used the properties recorded on 1,050 different cheeses from 107 producers grouped into 37 categories to analyze and quantify the interrelationships among the chemical and physical properties of many cheese types. The 15 cheese traits considered were ripening length, weight, firmness, adhesiveness, 6 different chemical characteristics, and 5 different color traits. As the 105 correlations between the 15 cheese traits were highly variable, a multivariate analysis was carried out. Four latent explanatory factors were extracted, representing 86% of the covariance matrix: the first factor (38% of covariance) was named Solids because it is mainly linked positively to fat, protein, water-soluble nitrogen, ash, firmness, adhesiveness, and ripening length, and negatively to moisture and lightness; the second factor (24%) was named Hue because it is linked positively to redness/blueness, yellowness/greenness, and chroma, and negatively to hue; the third factor (17%) was named Size because it is linked positively to weight, ripening length, firmness, and protein; and the fourth factor (7%) was named Basicity because it is linked positively to pH. The 37 cheese categories were grouped into 8 clusters and described using the latent factors: the Grana Padano cluster (characterized mainly by high Size scores); hard mountain cheeses (mainly high Solids scores); very soft cheeses (low Solids scores); blue cheeses (high Basicity scores), yellowish cheeses (high Hue scores), and 3 other clusters (soft cheeses, pasta filata and treated rind, and firm mountain cheeses) according to specific combinations of intermediate latent factors and cheese traits. In this case study, the high variability and interdependence of 15 major cheese traits can be substantially explained by only 4 latent factors, allowing us to identify and characterize 8 cheese type clusters.

Inactivation of Listeria monocytogenes by Hydrogen Peroxide Addition in Commercial Cheese Brines

Commercial cheese brines are used repeatedly over extended periods, potentially for years, and can be a reservoir for salt-tolerant pathogens, such as Listeria monocytogenes. The objective of this study was to determine the inactivation of L. monocytogenes in cheese brines treated with hydrogen peroxide (H2O2) (0, 50, and 100 ppm) at holding temperatures representing manufacturing conditions. In experiment one, four fresh cheese brines were prepared with 10 or 20% salt and pH 4.6 or 5.4 (2x2 design; duplicate trials). Brines were inoculated with L. monocytogenes, treated with H2O2, and stored at 10 and 15.6°C. For experiment two, seven used commercial brines (representing five cheese types, 15–30% NaCl, pH 4.5–5.5; three seasonal trials) were inoculated with L. monocytogenes or S. aureus, treated with H2O2, and stored at 12.8°C (both L. monocytogenes and S. aureus), 7.2 and 0°C (L. monocytogenes only). Each treatment was assayed on Days 0, 1, and 7 for microbial populations and residual H2O2. Data revealed that pathogen populations decreased ≤1 log in cheese brines with no hydrogen peroxide stored for 7 days, regardless of the storage temperature. In fresh brine treated with 50 or 100 ppm of H2O2, populations of L. monocytogenes were reduced to less than the detectable limit by 7 days at 10 and 15.6°C (>4 log reduction). For unfiltered used brines, H2O2 had no effect on L. monocytogenes populations in Brick J (pH 5.4, 15% NaCl) due to rapid inactivation of H2O2, likely by indigenous yeasts (∼3-log CFU/ml). For the remaining brines, the addition of 100 ppm H2O2 killed >4 log L. monocytogenes when stored at 7.2 or 12.8°C for 1 week, but only 3–4 log reduction when stored at 0°C. The addition of 50 ppm H2O2 had similar lethal effects at 12.8°C but was less effective at 7.2 or 0°C. Inactivation rates of S. aureus were similar to that of L. monocytogenes. This study confirmed that high salt, warmer temperature, and 100-ppm H2O2 accelerated the inactivation of L. monocytogenes in cheese brines. Data also suggest that the presence of catalase-positive indigenous microorganisms may neutralize the effect of H2O2.