Brine Cheese Research Articles

Protease, peptidase and esterase activities by lactobacilli and yeast isolates from Feta cheese brine.

The study of peptidase, esterase and caseinolytic activity of Lactobacillus paracasei subsp. paracasei, Debaryomyces hansenii and Sacchromyces cerevisiae isolates from Feta cheese brine. Cell-free extracts from four strains of Lact. paracasei subsp. paracasei, four strains of D. hansenii and three strains of S. cerevisiae, isolated from Feta cheese brine were tested for their proteolytic and esterase enzyme activities. Lactobacillus paracasei subsp. paracasei strains had intracellular aminopeptidase, dipeptidyl aminopeptidase, dipeptidase, endopeptidase and carboxypeptidase activities. Esterases were detected in three of four strains of lactobacilli and their activities were smaller with higher molecular weight fatty acids. The strains of yeasts did not exhibit endopeptidase as well as dipeptidase activities except on Pro-Leu. Their intracellular proteolytic activity was higher than that of lactobacilli. Esterases from yeasts preferentially degraded short chain fatty acids. Lactobacilli degraded preferentially beta-casein. Caseinolytic activity of yeasts was higher than that of lactobacilli. The results suggest that Lact. paracasei subsp. paracasei and yeasts may contribute to the development of flavour in Feta cheese. Selected strains could be used as adjunct starters to make high quality Feta cheese.

Experimental study and modeling of effective NaCl diffusion coefficients values during Emmental cheese brining

Experimental data concerning NaCl concentration profiles for industrially processed Emmental cheese were determined with cylindrical samples ensuring semi-infinite unidirectional mass transfer with saturated brining aqueous solutions for different temperature conditions in the range between 4 and 18 °C. Considering a binary diffusion system constituted by the cheese water and the NaCl solute, the NaCl diffusion kinetics were analyzed at each investigated temperature by three different approaches: firstly, using the second Fick’s law with a constant NaCl diffusivity, which gave a poor interpretation of the experimental data; secondly, using the Boltzmann’s method with a concentration dependent NaCl diffusion coefficient and thirdly, by numerical identification from the diffusion equation with an empirical variation of the NaCl diffusivity with the salt concentration (2nd order polynomial) and a boundary condition expressing the mass flux continuity at the interface. As a whole, the derived diffusivity values were found to be in good agreement with the previous published data concerning different cheese types. These two last analyses clearly indicated a decrease of the NaCl effective diffusivity with the salt concentration and, secondly, an increase of this diffusivity with the temperature. Finally, the last modelling, based on a quadratic reduction in the salt diffusivity with the salt concentration and on a Dirichlet (type II) limit condition lead to the best fitting between the measured and the predicted NaCl concentration profiles.

Development of salt profiles on Manchego type cheese during brining. Influence of vacuum pressure

Cheese brining is a slow process, consistent with the low values of salt diffusivity through the liquid phase trapped in the protein matrix, especially at low temperatures. The action of hydrodynamic mechanisms (HDM) in the porous protein matrix might accelerate mass transport by introducing brine directly in the pores. Promotion of HDM occurs when pressure gradients are applied to the system (e.g. applying vacuum). The influence of pressure in the system on the developing salt concentration profiles during brining of Manchego type cheese was analysed. Salting was carried out at atmospheric pressure (BI), at vacuum pressure (50 mbar) (VI) and by applying a vacuum pulse at the beginning of the process which then continued at atmospheric conditions (PVI). In VI brining, the developed salt concentration profiles can be better modelled by an advancing disturbance front model than by diffusional equations. Curd porosity and moisture greatly affected salt transport kinetics, in this case.

The antimicrobial effects of long-wave ultra-violet light and furocoumarins on some micro-organisms that occur in cheese brines

Listeria monocytogenes and Escherichia coli O157:H7 have been reported to survive in the brines used to store cheeses like Feta or Teleme, but such brines cannot be heat sterilized as the yeasts and lactic acid bacteria essential for normal cheese maturation are present as well. Long-wave UV light (UVA∼365 nm), acting in conjunction with photosensitizing compounds (e.g. furocoumarins like psoralen) might have more limited microbiocidal properties, so that, perhaps, pathogens could be eliminated from the cheese brine but not the desired yeasts and lactic acid bateria. In laboratory trials, UVA (intensity 45 W m−2, exposure time 60 s) with psoralen (5 mg l−1) was active againstListeria innocua —chosen to mimic the behaviour of L. monocytogenes—Escherichia coli O157:H7 andStaphylococcus aureus in a physiologically neutral solution, but E. coli O157:H7 (99% reduction in viable cell count) and L. innocua (99·8% reduction) were slightly less sensitive than S. aureus (99·99% reduction). Yeasts from Feta cheese brines were less affected by the same UVA/furocoumarin system—Debaryomyces hansenii (97·5% reduction) and Yarrowia lipolytica (82·7% reduction), as were typical lactic acid bacteria, namely Lactobacillus paracasei subsp. paracasei (97·8% reduction) and Lactobacillus plantarum (91·9% reduction). A UVA exposure time of 100 s with psoralen (5 mg l−1) was lethal to the ‘pathogens’ but, against the desirable species, onlyYarrowia lipolytica (97·4% reduction) readily survived the same treatment. It was concluded that the UVA/furocoumarin system was microbicidal but not, at least in the form under test, sufficiently selective in its action for use with cheese brines where certain of the microfloras need to be retained.

Current developments of microfiltration technology in the dairy industry

This paper deals with the most recent developments of cross flow microfiltration (CFMF), some of them just patented, in the dairy industry. Combination of the use of uniform trans- membrane hydraulic pressure concept (UTP) with its different ways of carrying out microfiltrate recirculation, longitudinal porosity gradient and of new ceramic membrane materials allows nowa- days to get a differential separation of each category of milk particles. Pretreatment by CFMF of incoming milk is used for the production of low heated fluid milks having a flavor similar to that of raw milk and a shelf life 3 to 5 times longer than that of classical products. Results observed in the retention by the MF membrane of pathogenic bacterial species allow it to be said that the hygienic safety of cheeses made from raw MF milk is, at least, equal or even higher than that of cheeses made from pasteurized milk. Numerous other applications of CFMF are under development such as removal of residual fat from whey or the clarification and the removal of bacteria from cheese brine but the most promising are undoubtedly the differential separation of micellar casein and of small milk fat globules. With the products obtained on both sides of the MF membrane, dairy technology will have the possibility not only to improve yield and quality of many dairy products but also to create a diversified range of new textures. microfiltration / membrane / liquid milk / native casein / brine / whey / cheese

Hydrocolloid coating of cheeses

Semi-hard and dry white brined cheeses were coated with hydrocolloid films based on κ-carrageenan, alginate and gellan. The cheeses were immersed in the gum solution followed by cross-linking of the gum solution to produce a coated product. A few coating films were then dried by airflow to induce better adherence of the coating to the coated object. The coated cheeses were stored at 4°C and at a relative humidity of 73%. Weight loss, gloss, roughness of surface area, changes in mechanical properties versus time (i.e. stress and strain at failure, stiffness and elastic properties), peel-bond strength of the coating film from the cheese and sensory evaluation were studied for each coated system. For the semi-hard cheese, all kinds of coatings reduced weight loss during 46days of storage. With regard to weight loss, no significant differences between the various coatings were found. The coating contributed to a better color and gloss. The roughness of the coated cheese decreased after coating, since surface ruggedness was filled in by the film. Advantages in the textural properties of the coated cheese were observed. Since the coated cheese lost less water by evaporation, a desirable softer and a less brittle texture was detected. The elastic properties of the cheeses were estimated by calculating the recoverable work (the ratio between recoverable and total compressive deformation) of coated and non-coated cheeses. This parameter appeared to decrease from ∼48 to 34% after 24days of storage; no advantage of the coated cheese was observed. The peel-bond strength of the film based on alginate was ∼1gforce/cm. In the case of the dry white brined cheese, no deliberate drying of the coated film was performed. All coatings reduced weight loss of the cheese with a significant advantage of the κ-carrageenan-based coating. The coatings contributed to a lower reduction in pH, thus a higher-quality cheese was obtained. In addition, the coated cheeses were softer and less brittle when compared to the non-coated cheese. The percentage of recoverable work of cheeses did not change even after 24days of storage. The coatings increased the gloss of the cheese fivefold in comparison to the non-coated cheese. In a sensory evaluation, the coated cheese was found to be advantageous over the non-coated system. In general, cheese coating based on hydrocolloid films improved textural and sensorial properties when compared to non-coated cheeses. The coatings did not influence the taste of white brined cheese, and the technology involved is simple and relatively inexpensive.

Survival of Salmonella typhimurium and Escherichia coli O157:H7 in cheese brines

Survival of Salmonella typhimurium and Escherichia coli O157:H7 was studied in model brines and brine from three cheese plants. Three strain mixtures of S. typhimurium and E. coli O157:H7 (10 6 CFU/ml) were inoculated separately into 23% model brine with or without added pasteurized whey (2%) and as a combined inoculum into the commercial brines. The model brines were incubated at 8 and 15°C for 28 days, and the commercial brines at 4 and 13°C for 35 days. Populations of both pathogens in the model brine+whey decreased slowly over 28 days (1.0–2.0 log CFU/ml) with greater survival at 8°C than at 15°C. Corresponding decreases in model brine without whey were 1.9–3.0 log CFU/ml, with greater survival at 8°C than at 15°C. Both S. typhimurium and E. coli O157:H7 survived significantly better ( P<0.05) at 4°C than at 13°C in two of the commercial brines. The survival of each pathogen in the commercial brines at 13°C was significantly influenced by brine pH. Both pathogen populations decreased most rapidly in commercial brines during the first week of storage (2.5–4.0 and 2.3–2.8 log CFU/ml for S. typhimurium and E. coli O157:H7, respectively) with significant recovery (ca. 0.5 log CFU/ml increase) often occurring in the second week of storage. Counts changed little thereafter. Overall, E. coli O157:H7 survived better than S. typhimurium, with differences of 0.1–1.2 log CFU/ml between the two pathogens. Results of this study show that cheese brine could support the survival of contaminating S. typhimurium and E. coli O157:H7 for several weeks under typical brining conditions.

Influence of milk centrifugation, brining and ripening conditions in preventing gas formation by Clostridium spp. in Gouda cheese

This study examined milk centrifugation, increased salt concentration, and low ripening temperature as potential strategies to prevent late blowing caused by gas-forming Clostridium spp. in Gouda cheese. The survival of clostridia spores in cheese brine and their ability to enter Gouda cheese during brining was also evaluated. Centrifugation (3000× g for 30 s) of contaminated milk resulted in >60% spore reduction, with increased spore reduction at greater centrifugal forces. Low levels of C. tyrobutyricum and C. sporogenes spores survived in saturated (23%, w/v) brine with 2% (v/v) added whey at 15°C for 63 days, while C. beijerinckii and C. butyricum spores were not detectable on days 4 and 35, respectively. Spores of C. tyrobutyricum in brine infiltrated Gouda cheese during 2 h of brining at 13°C resulted in production of small gas holes during ripening. In Gouda cheese slurry stored at 13°C, three C. tyrobutyricum strains plus one of three C. sporogenes strains germinated in the slurry with no added salt. Of three C. tyrobutyricum strains stored at 13°C in slurries with higher water-phase salt concentrations of 2.4 and 3.6%, two strains and one strain germinated, respectively. No germination of spores was detected in any cheese slurry stored at 5 or 8°C. Milk centrifugation, increased percent water-phase salt, absence of spores in brine, and decreased ripening temperature are all potentially important measures against gas production by Clostridium spp. in Gouda cheese.

Survival of Listeria monocytogenes in commercial cheese brines.

The survival of Listeria monocytogenes was determined in commercial cheese brines collected from cheese factories in Wisconsin and northern Illinois. Survival of L. monocytogenes inoculated into commercial cheese brines ranged from < 7 d to over 259 d. Survival did not correlate with pH, salt content, nitrogen content, mineral content, or inherent microbial populations but was negatively associated with addition of sodium hypochlorite at the dairy plant. The L. monocytogenes generally survived longer in brines held at 4 degrees C than at 12 degrees C. Sodium hypochlorite or hydrogen peroxide inactivated L. monocytogenes when added to commercial brines in the lab at 10 to 100 ppm or 0.001% to 0.02%, respectively. Addition of 1% potassium sorbate or 1% sodium benzoate also decreased survival of L. monocytogenes. Laboratory filtration of commercial brines had a negative effect on survival in one of three brines tested. The L. monocytogenes did not grow during incubation in any of the commercial brine samples tested.

Influence of ultrasound on mass transport during cheese brining

The effect of ultrasound on mass transfer during cheese brining has been investigated. The rate of water removal and NaCl gain increased when ultrasound was applied in comparison with brining performed under static or dynamic conditions, suggesting that ultrasound improves both external and internal mass transfer. A simple diffusional model was developed to simulate mass transport during acoustic brining. Model parameters were estimated using experimental data from acoustic brining experiments carried out on cheese cylinders of 1.7×10–2 m radius and 3×10–2 m height at different temperatures (5, 15 and 20 °C). Effective water (DW) and NaCl (DS) diffusivities estimated using the proposed model ranged from 5.0×10–10 m2/s and 8.0×10–10 m2/s at 5 °C to 1.3×10–9 m2/s and 1.2×10–9 m2/s at 20 °C. Both DW and DS varied with temperature according to the Arrhenius equation. Through the proposed model, water losses and NaCl gains of the experiments used in the parameter identification were accurately simulated (average %var=98.2%) and also of two additional acoustic experiments carried out under different conditions of temperature (10 °C) and sample size and geometry [parallelepiped of (6×2.5×1.25)×10–2 m] to those used in the parameter identification (average %var=98.4%).

Transport of sodium chloride and water in Gouda cheese as affected by high-pressure brining

Abstract The possibility of accelerating Gouda cheese brining by high-pressure treatment (100–500 MPa, 15–130 min) was investigated by comparison of the salt uptake of pressure-brined and nonpressure-brined Gouda cheese cylinders (∼8 g). The total amount of salt taken up by the cylinders was proportional to the square root of the brining time and was not influenced by pressure brining. In contrast, the water loss of the cheese cylinders was reduced by pressure brining at pressures above 200–300 MPa. No additional effect of a three-cycle process at 400 MPa was noticed on the salt uptake and water loss of the cheese cylinders. Moreover, the salt and water profiles of cheese (∼1.5 kg) brined for 24 h at 0.1 and 400 MPa were unaffected by high pressure. It was concluded that the salt uptake and salt diffusion cannot be accelerated by high-pressure brining, under the conditions specified.

Análise da difusão durante a salga de queijos por elementos finitos: influência combinada da discretização tempo-espacial

Numerical simulation of solute (sodium chloride) transfer process during salting through a three-dimensional matrix (cheese) was studied applying the finite element method. It was verified that both mesh refinement level and time step length were relevant to control oscillatory behaviors even when unconditional stability schemes as Crank-Nicolson and modified Euler were used. A discussion of the combined influence of time and space adaptation in the context of diffusion problem is also presented, taking in consideration a lumped capacity matrix to overcome the difficulties and determine the minimum length of the time step. Differential mathematical modeling had as theoretical basis the Fick’s second law. The proposed model brought good estimation of salt gain in the soft cheese studied. Choosing the appropriate mesh and a convenient time step length we suggest Crank-Nicolson scheme for the simulation of diffusion during cheese brining.

Halloumi cheese: the product and its characteristics

Halloumi, the traditional cheese of Cyprus, is extremely popular in the Middle East and the Mediterranean regions of Europe and in recent years exports from Cyprus have risen. The basic cheesemaking process places halloumi in the family of white brined cheeses, but some of its characteristics are quite unique. This paper reviews the studies that have been carried out on the chemical composition, manufacturing procedure(s), sensory quality and storage of halloumi, and considers some proposed developments, such as the use of reconstituted milk powders or homogenized milk.

The isolation of salt‐tolerant lactic acid bacteria from ovine and bovine milks for use in the production of nabulsi cheese

Nabulsi cheese is one of the most popular white brined cheeses produced in Jordan and, traditionally, no starter cultures are employed for ripening. However, the resultant high pH means that spoilage problems arise in cheeses stored at ambient temperatures. Direct acidification or the use of commercial starter cultures have an adverse effect on flavour, but cultures derived from lactic acid bacteria isolated from local milks gave rise to cheeses that were as acceptable as the traditional products. In addition, the pHs of the cheese brines were in the range associated with stability during storage (pH 5.1–5.3), and hence it is suggested that these locally derived cultures could be employed by the industry to manufacture a nabulsi cheese from pasteurized milk that should: (a) be free from pathogens; (b) not deteriorate in‐store at ambient temperature; and (c) have a flavour profile similar to traditional nabulsi cheese.

Evaluation of the physico-chemical characteristics of the curd during the ripening of Iranian brine cheese

Abstract Iranian pickled cheese (Feta type) was studied to determine the physico -chemical and biochemical changes that occur at various stages of ripening in brine. The concentration of free amino acids (FAA) decreased between the 30–50th day and increased thereafter. At the end of the 90th day ripening period, arginine, lysine and glutamic acid were predominant. Lipolysis occurred more slowly than proteolysis; palmitic and oleic acids were the principal free fatty acids (FFA) liberated.

Yeasts associated with Cheddar and Gouda making

Sources of yeast contamination which may lead to contamination of the curd during Cheddar and Gouda cheese making, were examined in a single cheese factory. A total of 187 representative yeast isolates present in the factory environment, on working surfaces, the brine and on workers' hands and aprons were identified according to conventional methods and cellular long-chain fatty acid analyses. Product line samples were taken at critical control points in the manufacturing process and analysed after incubation at 25 °C for 96 h. The most prevalent isolates belonged to the genera Debaryomyces and Candida. Other genera encountered were Cryptococcus, Rhodotorula, Yarrowia, Pichia, Trichosporon, Torulaspora, Issatchenkia, Saccharomyces and Zygosaccharomyces. Characterization of the the predominant yeast isolates indicated that the cheese brine was responsible for the largest variety and number of yeast isolates yielding a total of 64 yeast strains belonging to nine different genera.

Effect of various starters on the quality of cheese in brine

White brine cheeses from cow and sheep milk were produced and the effect of three different starter cultures (mesophilic, thermophilic and mixed) on the characteristics of white brine cheese was examined. [The mesophilic culture included Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris, the thermophilic culture included Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus and the mixed culture included Lactobacillus delbrueckii subsp. bulgaricus and Lactococcus lactis subsp. lactis.] The results indicated that adequate acidity was developed with the three cultures. The thermophilic starter culture was found to drop the pH of the product faster than the other two cultures during the first 24 h. However, after 2 months of maturation the pH of the cheeses made with this culture had statistically higher pH than the other two cultures. The moisture and hardness of the product was related to the pH, as expected. The soluble nitrogen as percentage of total nitrogen of samples was higher when the thermophilic starter was used. The higher proteolytic activity of the thermophilic culture was not apparent with the electrophoresis. During sensory evaluation of the cheeses, the cheese with the thermophilic culture received the least values (less preferred than the other cheeses) after the maturation of the samples. The other two cultures received similar marks on the sensory evaluation. The type of milk used was found to affect the characteristics of the cheese produced. After 10 and 60 days of maturation the cheeses from sheep's milk had lower moisture content and higher hardness and fracturability than cheese from cow's milk. In addition, from the electrophoretic patterns obtained, it appeared that the αs- and β-caseins were degraded faster in the cheeses from cow's milk than in the cheese from sheep's milk.

Study of Listeria monocytogenes contamination in a dairy plant and characterization of the strains isolated

From 1988 to 1990, a dairy plant was examined for Listeria contamination. Three hundred and forty samples were collected and analysed for the presence of Listeria. Sixty-one Listeria strains ( L. monocytogenes, 44, and L. Innocua, 17) were isolated from four varieties of cheese, cheese brines, process equipment and plant environment. The L. monocytogenes strains were recovered during the ripening and rind washing stages and not before, so it is likely that cheese contamination occurred at these points in the manufacturing process. The characterization of the isolated L. monocytogenes strains by serotyping and phage typing showed different serovars and phagovars. Some strains with the same serovar and the same phagovar were isolated from cheeses and process equipment (shelves) indicating that cheese contamination occurs during ripening. Only one profile was found from the analysis of the ribosomal ribonucleic acid (rRNA) gene restriction patterns of 38 L. monocytogenes strains with different serovars and phagovars. This suggests that all L. monocytogenes strains isolated in the dairy plant could have been derived from a single ancestral group.

Mathematical Model for Water Diffusion During Brining of Hard and Semi‐hard Cheese

ABSTRACTThe integral method, which is an approximate analytic method, was used to obtain the theoretical profile of moisture changes during brining of cheese. A mass layer was defined in the model where all water variations take place. The model was applied at different times to semi‐hard cheese brining and compared with experimental data. A moisture pseudo diffusion coefficient was obtained from experimental data as part of the proposed model. Agreement was good, which demonstrated the applicability of the model.

The yeasts of cheese brines

A total of 365 yeasts were isolated from the brines of soft, semihard and hard cheeses from different manufacturers. Identification was based on 131 characteristics, primarily employing a method with microtitration plates. Most brines exhibited a characteristic yeast flora. The predominant strains proved to be mainly Debaryomyces hansenii and Candida versatilis. In a few brines Trichosporon beigelii, C. rugosa, C. intermedia, Kluyveromyces marxianus, Saccharomyces sp. and C. tenius/polymorpha were predominant. Also of importance were C. tropicalis, C. parapsilosis, C. zeylanoides, Issatchenkia orientalis and Geotrichum klebahnii. Not all strains could be clearly identified. Lists of characters are provided for subdividing D. hansenii and T. beigelii. The specificity of the yeast flora of brines is assumed to contribute to the sensory variety of cheeses.