CHANGES IN CHEMICAL, SENSORY AND RHEOLOGICAL CHARACTERISTICS OF MANCHEGO CHEESES DURING RIPENING

Manchego cheese is a high-fat pressed ewe's-milk cheese made in Castilla-La Mancha (Spain) and produced by enzymatic coagulation. The minimum ripening time before marketing required by the Regulatory Board of the Manchego Cheese Appellation of Origin is 60 days.
This paper describes the physicochemical, proteolysis, sensory and texture characteristics of Manchego cheese, and the degree of homogeneity of cheeses made under the Manchego Appellation of Origin. The data gathered in this study indicate that sensory and instrumental analysis are useful tools for detecting changes in Manchego cheese during ripening. These changes were first detected by the instrumental analysis (2 months). The panelists detected differences after 4 months' ripening in all the factories. With physicochemical analysis, on the other hand, longer ripening times (6–8 months) are required before such changes become appreciated.     

Winter feeding systems and dairy cow breed have an impact on milk composition and flavour of two Protected Designation of Origin French cheeses

This study investigates the effects of two feeding systems and two dairy cow breeds on milk yield and composition, physical and sensorial properties of Camembert and Pont-l’Evêque cheeses. The experiment consisted of a 2 × 2 factorial arrangement of treatments. A low energy grass diet with only 15% of concentrate (LowGS) was compared with a high-energy maize silage diet with 30% concentrate (HighMS). Thirty-four Holstein (Ho) and 34 Normande (No) cows in early lactation were assigned to one of two feeding systems for a 6-week period. Cows on the LowGS feeding system had lower milk yield, fat and protein content. In both feeding systems, No cows had lower milk yields but higher milk protein contents than Ho cows. The LowGS feeding system altered milk fatty acid (FA) composition by reducing saturated FA. Breed had only a small impact on milk FA. Concerning milk coagulating properties, only the firmness was reduced by the LowGS feeding and the Ho breed. The effects of breed and feeding system on the protein content of cheeses were more marked in Camembert cheese than in Pont-l’Evêque cheese. However, the Camembert cheese from Ho-LowGS was, in fact, characterized especially by lower protein content. LowGS feeding system and No breed produced more yellow cheeses. Feeding systems had limited effects on the firmness of Camembert and Pont-l’Evêque cheeses measured by penetrometry. In sensory analysis, Ho breed and LowGS feeding produced a Camembert cheese with a more melting texture in the mouth due to the increase of spreadability index and of proteolysis. The type of cheese also had an influence: the effects were more important on Camembert cheese than on Pont-l’Evêque cheese. Only the Ho-LowGS treatment produced a very specific Camembert cheese different from the others. The feeding systems and breed of dairy cow have no determinant effect on PDO (protected designation of origin) Camembert and Pont-l’Evêque cheeses, especially regarding taste. In this kind of trial, despite the effects of feeding systems and breed on milk composition, the role of cheese ripening and microbiology appears to be of considerable importance.     

The effect of a commercial starter culture addition on the ripening of an artisanal goat's cheese (Cameros cheese)

The evolution of physicochemical parameters, and the most important microbial groups, were determined for the following three batches of 'Cameros' goat's milk cheese during ripening: Batch R elaborated with raw milk, Batch RS elaborated with raw milk and with the addition of a starter culture, and Batch PS elaborated with pasteurized milk and with the addition of the same culture. No differences in total solids (TS) or in the content of NaCl, fat and total nitrogen (expressed as percentages of TS) were found during the ripening. The pH, fat acidity and non-protein nitrogen (NPN, expressed as a percentage of TN) showed significant differences between the batches. The inoculated batches showed the fastest drop in pH at the beginning of the ripening period, but the cheeses of Batch R showed a higher degree of lipolysis and proteolysis. The addition of a starter influenced the microbiological quality of the cheeses. Differences in the counts of Enterobacteriaceae and faecal coliforms were found between Batches R and RS after 15 days. Staphylococcus aureus increased in number during the early period of ripening and attained a population above 6 log cfu g-1 in Batch R in the period from 5 to 10 days. However, enterotoxins were not detected in this Batch. Batch R showed lower values of lactic acid bacteria at the beginning of the ripening period, but no significant differences were found between batches in the period from 5 to 15 days of ripening. At the beginning of the ripening, Lactococcus was the main lactic acid bacteria, with L. lactis lactis being predominant. After 15 days, the lactic acid bacteria counts decreased in the three batches, especially in the cheeses of Batch PS (only 2.2 log cfu g-1 was found at 60 days), as lactococci (the only lactic acid bacteria present in Batch PS) are incapable of growing under the conditions found in cheeses at the end of their ripening period. At this time, Lactobacillus was the predominant genus in Batches R and RS, with L. plantarum predominant. No lactococci were found from day 30 in Batch R and from day 40 in Batch RS. The cheeses of Batch RS received the most favourable scores from the tasting panel for all attributes judged: cut appearance, colour, aroma, taste, texture and general acceptance.     

1H HRMAS-NMR based metabolic fingerprints for discrimination of cheeses based on sensory qualities

In this study, the ¹H HRMAS-NMR (High-resolution Magic Angle Spinning-Nuclear Magnetic Resonance) spectra of 52 cheese samples obtained from the South Korean dairy farms were evaluated for their metabolic profiling and intensities associating with the sensory qualities. The NMR profiles displayed a broad range of compounds comprising amino acids, carbohydrates, organic acids, and phospholipids. Afterwards, the cheese samples were categorized into three groups (more likeness - G1, moderate likeness - G2, less likeness - G3), in relating to their sensory scores. The NMR data of the samples were later investigated through multivariate statistical tools to define the variations in metabolic fingerprints of every cheese sample and their intensities hailing in individual sensory groups. The unsupervised PCA employing all cheese samples unveiled the uniqueness in metabolite profiles of the brown and cheddar type cheeses (outliers). Moreover, Gouda and other types of cheeses displayed samples positioning in respective of their metabolite profiles. The pairwise comparison of sensory groups in the supervised models perceived better separation in OPLS-DA than PLS-DA. The corresponding VIP (PLS-DA) and loading (OPLS-DA) plots revealed amino acids and organic acids (lactate, citrate) as significant variables. The discrimination of G 1 Gouda type of cheeses against G 2 and G 3 was highly associated with their citrate levels. Further investigation using heatmaps displayed clear differentiation between each sensory group in terms of the levels of amino acids, lactate, citrate, phospholipids, and glycerol, conveying these variations are likely due to proteolytic and metabolic processes in cheese ripening. This study concluded that ¹H HRMAS-NMR metabolite profile of the Korean cheeses is consistence with their sensory qualities. Further, the candidate metabolites identified in this study confers their potential application as biomarkers in cheese industries for faster and effective validation of sensory characteristics.     

ABILITY OF HAND EVALUATION VERSUS MOUTH EVALUATION TO DIFFERENTIATE TEXTURE OF CHEESE

Hand evaluation and mouth evaluation were compared for texture of cheese. Panelists (n = 11) identified seven mouth terms and five hand terms and developed definitions and standard procedures for evaluation during the course of training. The terms were used to evaluate texture properties of fourteen different types of natural and processed full fat and reduced fat cheeses. Hand and mouth evaluation were able to discriminate cheese texture (P≦0.05). Principal component analysis of data revealed that hand and mouth evaluation differentiated the cheeses in a similar manner. Correlation analysis, factor analysis, and canonical analysis revealed that mouth and hand terms were highly correlated (P≦0.05). Either hand or mouth evaluation can be used to discriminate cheese texture.     

Spatial Distribution of Lactococcus lactis Colonies Modulates the Production of Major Metabolites during the Ripening of a Model Cheese

In cheese, lactic acid bacteria are immobilized at the coagulation step and grow as colonies. The spatial distribution of bacterial colonies is characterized by the size and number of colonies for a given bacterial population within cheese. Our objective was to demonstrate that different spatial distributions, which lead to differences in the exchange surface between the colonies and the cheese matrix, can influence the ripening process. The strategy was to generate cheeses with the same growth and acidification of a Lactococcus lactis strain with two different spatial distributions, big and small colonies, to monitor the production of the major ripening metabolites, including sugars, organic acids, peptides, free amino acids, and volatile metabolites, over 1 month of ripening. The monitored metabolites were qualitatively the same for both cheeses, but many of them were more abundant in the small-colony cheeses than in the big-colony cheeses over 1 month of ripening. Therefore, the results obtained showed that two different spatial distributions of L. lactis modulated the ripening time course by generating moderate but significant differences in the rates of production or consumption for many of the metabolites commonly monitored throughout ripening. The present work further explores the immobilization of bacteria as colonies within cheese and highlights the consequences of this immobilization on cheese ripening.     

Effect of several MAP compositions on the microbiological and sensory properties of Graviera cheese

The shelf life of Graviera cheese, a full fat cheese produced in Heraklion (Crete Greece), was investigated. Graviera cheese was stored at 4 °C for up to 90 days in polyamide packages under three different modified atmosphere compositions. Control cheeses were packaged in air whereas MAP mixtures were MAP₁: 40% CO₂/55% N₂/5% O₂, MAP₂: 60% CO₂/40% N₂ and MAP₃: 50% CO₂/50% N₂. Sampling of product was carried out every 10 days to investigate its sensory quality and microbiological characteristics. Ten trained panelists participated in the sensory panel to evaluate the cheeses for external appearance (color, texture), taste, and flavor in a scale from 1 to 10 (1 very poor, 10 very good). The microbiological analysis revealed that there were no colonies of Staphylococcus aureus and Listeria monocytogenes whereas both Escherichia coli and Total Viable Counts (TVC) increased strongly in control samples but were inhibited under all MAP compositions.     

Persistence of Mycobacterium paratuberculosis during manufacture and ripening of cheddar cheese

Model Cheddar cheeses were prepared from pasteurized milk artificially contaminated with high 10(4) to 10(5) CFU/ml) and low (10(1) to 10(2) CFU/ml) inocula of three different Mycobacterium paratuberculosis strains. A reference strain, NCTC 8578, and two strains (806PSS and 796PSS) previously isolated from pasteurized milk for retail sale were investigated in this study. The manufactured Cheddar cheeses were similar in pH, salt, moisture, and fat composition to commercial Cheddar. The survival of M. paratuberculosis cells was monitored over a 27-week ripening period by plating homogenized cheese samples onto HEYM agar medium supplemented with the antibiotics vancomycin, amphotericin B, and nalidixic acid without a decontamination step. A concentration effect was observed in M. paratuberculosis numbers between the inoculated milk and the 1-day old cheeses for each strain. For all manufactured cheeses, a slow gradual decrease in M. paratuberculosis CFU in cheese was observed over the ripening period. In all cases where high levels (>3.6 log(10)) of M. paratuberculosis were present in 1-day cheeses, the organism was culturable after the 27-week ripening period. The D values calculated for strains 806PSS, 796PSS, and NCTC 8578 were 107, 96, and 90 days, respectively. At low levels of contamination, M. paratuberculosis was only culturable from 27-week-old cheese spiked with strain 806PSS. M. paratuberculosis was recovered from the whey fraction in 10 of the 12 manufactured cheeses. Up to 4% of the initial M. paratuberculosis load was recovered in the culture-positive whey fractions at either the high or low initial inoculum.     

Influence of ripening container on the lactic acid bacteria population in Tulum cheese

The objective of the present study was to investigate the influence of container material (plastic or goat-skin bag) on the growth of lactic acid bacteria in Tulum cheese during 9 months of ripening. The lactic acid bacteria in Tulum cheeses were periodically counted on MRS and M17 agars throughout ripening. Results showed that the highest counts of lactic acid bacteria on MRS or M17 were observed at the beginning of ripening and their counts decreased during later stages of ripening. The cheese samples ripened in plastic bags exhibited higher numbers of LAB on MRS and M-17 agars than those ripened in goat-skin bags. A total of 112 strains of lactic acid bacteria were isolated from Tulum cheeses ripened in plastic or goat-skin bags during ripening. The lactic acid bacteria present in the cheese were classified by Microbial Identification System (MIS) based on a comparison of the fatty acid methyl ester profiles. Different species including Enteroccocus, Lactobacillus, Streptococcus, Lactococcus and Pediococcus genera were found in unripened cheese. As ripening proceeded, the species Streptococcus and Lactococcus disappeared and the percentages of the species Enterococcus was unchanged in both containers. There were slight differences between the cheeses ripened in plastic or goat-skin bags in terms of the profiles of lactic acid bacteria isolated. Some species including L. brevis, L. mesenteroides subsp. dextranicum, P. damnosus and E. mundtii were isolated only in the cheeses ripened in plastic bags; however, L. coryniformis and L. malafermentans were isolated only in the cheeses ripened in goat-skin bags at 6 or 9 months of ripening. Also the numbers of E. faecalis isolates were higher in the cheeses ripened in plastic containers than cheeses ripened goat-skin bags at the 6 or 9 months of ripening. The results showed that Lactobacillus and Enterococcus were the predominant species in matured Tulum cheeses in both ripening containers. It seemed possible to produce Tulum cheese with similar characteristics from both the containers used.     

Manufacture of Cheddar cheese using probiotic Lactobacillus plantarum K25 and its cholesterol-lowering effects in a mice model

The probiotic adjunct Lactobacillus plantarum K25 was inoculated into milk to produce probiotic cheese. The effect of Lb. plantarum K25 on cheese composition, microbiological growth and survival during the manufacturing and ripening period, primary and secondary proteolysis during cheese ripening, and the in vivo cholesterol-lowering ability of the probiotic cheese were investigated. The results showed that the use of adjunct Lb. plantarum K25 in Cheddar cheese did not affect the cheese components including moisture, protein, fat, salt content and the pH value of cheese. During the whole ripening period, the probiotic adjunct maintained its viability, suggesting the effectiveness of Cheddar cheese as a vehicle for delivery of probiotic bacteria. No significant differences were observed in water-soluble nitrogen, 70?% ethanol-soluble nitrogen, 5?% phosphotungstic acid-soluble nitrogen, free amino acids and urea-PAGE patterns between the control and probiotic cheeses. Assessment of the in vivo cholesterol-lowering property of cheese with Lb. plantarum K25 showed that the levels of serum total cholesterol, low-density lipoprotein cholesterol and triglycerides decreased significantly, and the level of serum high-density lipoprotein cholesterol increased in mice fed with the probiotic cheese. The results indicated the potential function as a dietary item of the probiotic cheese with Lb. plantarum K25 to reduce the risk of cardiovascular diseases.     

Fate of Mycobacterium avium subsp. paratuberculosis in Swiss hard and semihard cheese manufactured from raw milk

Raw milk was artificially contaminated with declumped cells of Mycobacterium avium subsp. paratuberculosis at a concentration of 10(4) to 10(5) CFU/ml and was used to manufacture model hard (Swiss Emmentaler) and semihard (Swiss Tisliter) cheese. Two different strains of M. avium subsp. paratuberculosis were tested, and for each strain, two model hard and semihard cheeses were produced. The survival of M. avium subsp. paratuberculosis cells was monitored over a ripening period of 120 days by plating out homogenized cheese samples onto 7H10-PANTA agar. In both the hard and the semihard cheeses, counts decreased steadily but slowly during cheese ripening. Nevertheless, viable cells could still be detected in 120-day cheese. D values were calculated at 27.8 days for hard and 45.5 days for semihard cheese. The most important factors responsible for the death of M. avium subsp. paratuberculosis in cheese were the temperatures applied during cheese manufacture and the low pH at the early stages of cheese ripening. Since the ripening period for these raw milk cheeses lasts at least 90 to 120 days, the D values found indicate that 10(3) to 10(4) cells of M. avium subsp. paratuberculosis per g will be inactivated.     

Effect of enterocin CCM 4231 on Listeria monocytogenes in Saint-Paulin cheese

The bacteriocin production byEnterococcus faecium strain in cheese milk and cheese was demonstrated. Purified enterocin CCM 4231 exhibited an anti-listerial effect during Saint-Paulin cheese manufacture. During cheese production the strain grew to a final concentration of 10.1±0.01 log CFU per mL per g in cheese. Then only a slight decrease of the cell concentration was noticed during ripening and was almost stable for 8 weeks. No significant differences in pH were observed between the experimental and reference cheeses. Bacteriocin production during cheese manufacture was detected only in milk samples and curd, reaching a level of 100 AU/mL. After addition of purified enterocin CCM 4231 (concentration 3200 AU/mL) into the experimental cheese, the initial concentration of 6.7±0.06 log CFU per mL ofListeria monocytogenes Ohio was reduced up to 1.9±0.01 log CFU per mL per g. After 6 weeks and at the end of the experiment the difference of surviving cells ofL. monocytogenes Ohio in ECH was only one or 0.7 log cycle compared to the control cheese. Although enterocin CCM 4231 partially inhibitedL. monocytogenes in Saint-Paulin cheese manufacture, an inhibitory effect of enterocin added was shown in 1-week cheese; however, it was not possible to detect bacteriocin activity by the agar spot test. The traditional fermentation and ripening process was not disturbed, resulting in acceptable end-products, including sensory aspects.     

Evaluation of amino acid-decarboxylative microbiota throughout the ripening of an Italian PDO cheese produced using different manufacturing practices

Aim:  To investigate the presence of biogenic amines (BAs) in Montasio cheese produced by using different cheese manufacturing practices.
Methods and Results:  Three batches of Montasio cheese were made in the following way: batch A using raw milk and natural milk culture, batch B with thermized milk and natural milk culture and batch C with thermized milk and natural milk culture added of a commercial starter culture. During 120 days of ripening analyses were performed for microbial counts and BA content; indeed, the potential to produce BAs was screened in lactic acid bacteria and Enterobacteriaceae isolates. At the end of ripening, the total BA contents of cheeses from batches A, B and C were 166·3, 207·3 and 29·8 mg kg⁻¹, respectively. Amino acid decarboxylase activity was widespread among isolates.
Conclusions:  The BA content of Montasio cheese from the three batches was below the threshold proposed as potentially toxic. The highest BA content was found in cheese produced using thermized milk and natural milk culture; therefore, the thermal treatment of milk was not enough by itself to reduce the counts of decarboxylase-positive bacteria in cheese. The use of selected starters guaranteed a low BA content in Montasio cheese.
Significance and Impact of the Study:  The study of the effects of some technological processes on the incidence of decarboxylative microbiota in 'protected denomination of origin' cheeses could provide useful information on the hygienic risk related to their production.     

Microbiological,physical–chemical and sensory evaluation of a traditional Brazilian cheese during the ripening process

The ripening process of the traditional Serra do Salitre cheese, a Brazilian Minas cheese variety, was studied on five farms during 60 days. Faecal coliforms decreased and were not detected after ripening for this period. The contamination by coagulase-negative Staphylococcus was reduced at the end of the ripening period only on farms 3 and 4. Staphylococcus aureus was detected only in fresh cheese on farm 5 and decreased in number until it disappeared. No S. aureus was observed in the fresh cheeses from farms 2 and 4, but these were contaminated, probably by the hands of the manipulators, during the ripening process. The humidity decreased and the proteolysis increased during ripening. No correlation of the salt content and the humidity with the degree of proteolysis was observed. The degree of acceptance in the sensory evaluation was higher for cheese that had ripened for 1 and 15 days.     

Reducing Biogenic-Amine-Producing Bacteria,Decarboxylase Activity,and Biogenic Amines in Raw Milk Cheese by High-Pressure Treatments

Biogenic amines may reach concentrations of public health concern in some cheeses. To minimize biogenic amine buildup in raw milk cheese, high-pressure treatments of 400 or 600 MPa for 5 min were applied on days 21 and 35 of ripening. On day 60, counts of lactic acid bacteria, enterococci, and lactobacilli were 1 to 2 log units lower in cheeses treated at 400 MPa and 4 to 6 log units lower in cheeses treated at 600 MPa than in control cheese. At that time, aminopeptidase activity was 16 to 75% lower in cheeses treated at 400 MPa and 56 to 81% lower in cheeses treated at 600 MPa than in control cheese, while the total free amino acid concentration was 35 to 53% higher in cheeses treated at 400 MPa and 3 to 15% higher in cheeses treated at 600 MPa, and decarboxylase activity was 86 to 96% lower in cheeses treated at 400 MPa and 93 to 100% lower in cheeses treated at 600 MPa. Tyramine, putrescine, and cadaverine were the most abundant amines in control cheese. The total biogenic amine concentration on day 60, which reached a maximum of 1.089 mg/g dry matter in control cheese, was 27 to 33% lower in cheeses treated at 400 MPa and 40 to 65% lower in cheeses treated at 600 MPa. On day 240, total biogenic amines attained a concentration of 3.690 mg/g dry matter in control cheese and contents 11 to 45% lower in cheeses treated at 400 MPa and 73 to 76% lower in cheeses treated at 600 MPa. Over 80% of the histidine and 95% of the tyrosine had been converted into histamine and tyramine in control cheese by day 60. Substrate depletion played an important role in the rate of biogenic amine buildup, becoming a limiting factor in the case of some amino acids.     

Presence of halophilic and alkaliphilic lactic acid bacteria in various cheeses

AIM: We sought to confirm the presence of halophilic and alkaliphilic lactic acid bacteria (HALAB) of marine origin in cheeses and thus contribute to the understanding of the roles of LAB flora in cheese ripening. METHODS AND RESULTS: We used 7% NaCl glucose-yeast extract-peptone-fish extract broth and agar media (pH 9.5) for pour-plating and enrichment culture for 16 cheese samples produced in six European countries. HALAB were present in 9 of the 16 samples at < 20 --> 10(7) CFU g(-1). In three mould-ripened soft cheeses, HALAB counts ranged from 10(6) to 10(7) CFU g(-1) and were one order (two samples) and six orders (one sample) of magnitude greater than that of nonhaloalkaliphilic, common LAB, as enumerated on lactobacilli MRS agar. The 16S rRNA gene sequences (500 bp) of 51 of the 55 isolates examined were identical or similar to that of Marinilactibacillus psychrotolerans or Alkalibacterium olivapovliticus and related species, all of which are HALAB. CONCLUSIONS: HALAB of possible marine origin were present in various soft, semi-hard and semi-soft cheeses and were highly predominant in some mould-ripened cheeses. Significance AND IMPACT OF THE STUDY: HALAB of possible marine origin are members of the microflora of various cheeses and, when dominant, may play a role in the ripening of cheeses. Microbial analysis of LAB flora in cheeses should take into consideration the presence of HALAB.