Pasteurized Milk Cheese Research Articles

Development of volatile sulfur compounds in heat-shocked and pasteurized milk cheese

The development of volatile sulfur compounds in heat-shocked and pasteurized milk cheese was studied over a period of 20 months. The concentration of volatile sulfur compounds was determined using a headspace solid phase microextraction gas chromatography-pulsed flame photometric detection method. The standard curves were prepared in the cheese matrix and two internal standards were used for quantification. The result showed that hydrogen sulfide and, dimethyl disulfide (DMDS) only increased in the initial stage of cheese aging and reached a plateau, whereas methanethiol (MeSH), dimethyl sulfide (DMS) and dimethyl trisulfide (DMTS) continued to develop as the cheese aged. Cheddar cheese made from heat-shock milk developed higher concentrations of MeSH, DMS, DMDS, and DMTS than the cheeses made from pasteurized milk. It was postulated that lower heat treatment would preserve some of the native bacteria in the milk, and enhance volatile sulfur development in cheeses made from heat-shocked milk.

High-Pressure Processing of Turkish White Cheese for Microbial Inactivation

High-pressure processing (HPP) of Turkish white cheese and reduction of Listeria monocytogenes, total Enterobacteriaceae, total aerobic mesophilic bacteria, total molds and yeasts, total Lactococcus spp., and total Lactobacillus spp. were investigated. Cheese samples were produced from raw milk and pasteurized milk and were inoculated with L. monocytogenes after brining. Both inoculated (ca. 107 to 108 CFU/g) and noninoculated samples were subjected to HPP in a high-pressure food processor at 50 to 600 MPa for 5 and 10 min at 25°C. Reductions in L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp., and Lactobacillus spp. in both pasteurized- and raw-milk cheese samples and reductions in total molds and yeasts and total Enterobacteriaceae counts in raw-milk cheese samples increased with increased pressure (P ≤ 0.05). The maximum reduction of the L. monocytogenes count, ca. 4.9 log CFU/g, was obtained at 600 MPa. Because of the highly inhibitory effect of pasteurization, the total molds and yeasts and total Enterobacteriaceae counts for the cheese samples produced from pasteurized milk were below the detection limit both before and after HPP. There was no significant difference in inactivation of L. monocytogenes, total aerobic mesophilic bacteria, Lactococcus spp., and Lactobacillus spp. under the same treatment conditions for the raw milk and pasteurized milk cheeses and for 5- and 10-min treatment times (P > 0.05). No significant change was detected in pH or water activity of the samples before and after HPP. Our findings suggest that HPP can be used effectively to reduce the microbial load in Turkish white cheese.

Utilization of Microfiltration or Lactoperoxidase System or Both for Manufacture of Cheddar Cheese from Raw Milk

The objective of the present study was to determine if application of microfiltration (MF) or raw milk lactoperoxidase system (LP) could reduce the risk of foodborne illness from Escherichia coli in raw milk cheeses, without adversely affecting the overall sensory acceptability of the cheeses. Escherichia coli K12 was added to raw milk to study its survival as a non-pathogenic surrogate organism for pathogenic E. coli. Five replications of 6 treatments of Cheddar cheese were manufactured. The 6 treatments included cheeses made from pasteurized milk (PM), raw milk (RM), raw milk inoculated with E. coli K12 (RME), raw milk inoculated with E. coli K12 + LP activation (RMELP), raw milk inoculated with E. coli K12 + MF (MFE), and raw milk inoculated with E. coli K12 + MF + LP activation (MFELP). The population of E. coli K12 was enumerated in the cheese milks, in whey/curds during cheese manufacture, and in final Cheddar cheeses during ripening. Application of LP, MF, and a combination of MF and LP led to an average percentage reduction of E. coli K12 counts in cheese milk by 72, 88, and 96%, respectively. However, E. coli K12 populations significantly increased during the manufacture of Cheddar cheese for the reasons not related to contamination. The number of E. coli K12, however, decreased by 1.5 to 2 log cycles during 120 d of ripening, irrespective of the treatments. The results suggest that MF with or without LP significantly lowers E. coli count in raw milk. Hence, if reactivation of E. coli during cheese making could be prevented, MF with or without LP would be an effective technique for reducing the counts of E. coli in raw milk cheeses. The cheeses were also analyzed for proteolysis, starter and nonstarter lactic acid bacteria (NSLAB), and sensory characteristics during ripening. The concentration of pH 4.6 soluble nitrogen at 120 d was greater in PM cheese compared with the other treatments. The level of 12% trichloroacetic acid-soluble nitrogen at 120 d was greater in RM, RME, and RMELP cheeses compared with PM, MFE, and MFELP cheeses. This could be related to the fact that cheeses made from raw milk with or without LP (RM, RME, and RMELP) had greater levels of NSLAB compared with PM, MFE, and MFELP cheeses. Cheeses at 60 d, as evaluated by 8 trained panelists, did not differ in bitterness, pastiness, or curdiness attributes. Cheeses at 120 d showed no differences in acid-taste, bitterness, or curdiness attributes. Sensory analysis at 60 d showed that PM and MFELP cheeses had greater overall sensory acceptability than RM and RME cheeses. The overall sensory acceptability of the cheeses at 120 d showed that PM, MFE, and MFELP cheeses were more acceptable than RM and RME cheeses.

Microbiological quality of retail cheeses made from raw, thermized or pasteurized milk in the UK

Two studies of retail fresh, ripened and semi-hard cheeses made from raw, thermized or pasteurized milk were undertaken in the UK during 2004 and 2005 to determine the microbiological quality of these products. Using microbiological criteria in European Commission Recommendations 2004/24/EC and 2005/175/EC, 2% of both raw, thermized (37/1819 samples) and pasteurized (51/2618 samples) milk cheeses were of unsatisfactory quality. Raw or thermized milk cheeses were of unsatisfactory quality due to levels of Staphylococcus aureus at ⩾10 4 cfu g −1, Escherichia coli at ⩾10 5 cfu g −1, and/or Listeria monocytogenes at ⩾10 2 cfu g −1, whereas pasteurized milk cheeses were of unsatisfactory quality due to S. aureus at ⩾10 3 cfu g −1 and/or E. coli at ⩾10 3 cfu g −1. Salmonella was not detected in any samples. Cheeses were of unsatisfactory quality more frequently when sampled from premises rated as having little or no confidence in management and control systems, and stored/displayed at above 8 °C. Raw or thermized milk cheeses were also more likely to be of unsatisfactory quality when they were unripened types, and pasteurized milk cheeses when they were: semi-hard types; from specialist cheese shops or delicatessens; cut to order. These results emphasize the need for applying and maintaining good hygiene practices throughout the food chain to prevent contamination and/or bacterial growth. Labelling of cheeses with clear information on whether the cheese was prepared from raw milk also requires improvement.

Effect of Pretreatment of Milk Quality Characteristics of Jibna-Beida (White Cheese)

The objective of this study was to investigate the effect of heat treatment of milk on the quality characteristics of Jibna-beida (white cheese). The heat treatment methods used included pasteurization of cow milk at 65oC for 30 min, and boiling of cow milk at 102oC for 15 min. The microbiological analysis indicated that raw milk contained high counts of total viable microbes, coliforms, staphylococci, yeast and mould. However, all these microbial groups were highly reduced in pasteurized and boiled milk. Jibna–beida was prepared using the three types of milk: raw, pasteurized and boiled. The raw milk cheese contained: 43.0% moisture, 12.5% ash, 20.16% protein and 56.48% total soluble solids, while the pasteurized milk cheese contained: 50.9% moisture, 10.5% ash, 17.63% protein and 48.76% total soluble solids and the boiled milk cheese contained: 48.5% moisture, 13.4% ash, 15.4% protein and 55.75% total soluble solids. During storage, the pH of all cheese samples decreased and the acidity increased. The microbiological analysis of the three types of cheese indicated that the microbial load of raw milk cheese was higher when compared with those of pasteurized and boiled milk cheeses. The sensory evaluation revealed acceptance of the three types of cheeses with preference to the raw milk cheese than the other two types of cheese.

Volatile composition and sensory properties of industrially produced Idiazabal cheese

The volatile composition and sensory properties of industrially produced Idiazabal cheeses made from ewes’ raw milk (RM) or pasteurised milk (PM) and with addition of different starter cultures were compared. Cheeses were analysed at 90 and 180 d of ripening. Acids were the major volatile compounds in RM cheeses. Methyl ketones were the major volatile compounds in PM cheeses at 90 ripening days. However, the content of acids strongly increased with ripening whereas the content of ketones decreased in PM cheeses. The concentration of esters was higher in RM cheeses than in PM cheeses. No differences were found in the content of alcohols. Most aldehydes, hydrocarbons, terpenes and furans identified were minor volatile compounds in both RM and PM cheeses. In RM cheeses, characteristic sensory attributes for the aroma of Idiazabal cheese were present at 3 months, whereas in PM cheeses those desirable sensory attributes did not appear until 6 months of ripening.

Queso Chihuahua: effects of seasonality of cheesemilk on rheology†

Fresh semihard raw milk (RM) and pasteurized milk (PM) cheeses made by Mennonite communities in Chihuahua, Mexico were sampled in early winter, mid‐spring and late summer and evaluated during storage to determine if rheological properties were affected by the season the cheese was produced. Seasonal effects were observed in the rheology of the RM cheeses, which underwent more extensive proteolysis than the PM cheeses. The rheological properties of the PM cheeses and the composition of all cheeses were consistent throughout the year. The texture of the RM cheese is affected by season, whereas the variability in texture and composition of PM cheese is minimal, allowing for the manufacture of a uniform product.

Mexican Queso Chihuahua: rheology of fresh cheese†

Rheological properties of fresh Queso Chihuahua made from raw milk (RM) or pasteurized milk (PM) were characterized using texture profile, torsion and small amplitude oscillatory shear analyses. Although the rheological properties varied significantly among the different brands with overlapping ranges for the individual RM and PM cheese brands, overall the PM cheeses were harder, chewier and more cohesive but had lower viscoelastic values than the RM cheeses. Establishing the rheological properties of Mexican Queso Chihuahua increases our understanding of the quality traits of Hispanic‐style cheeses and provides a foundation for maintaining the traditional texture of the cheese.

IMPACT OF FROZEN STORAGE ON FLAVOR OF CAPRINE MILK CHEESES

ABSTRACT The impact of freezing and frozen storage on flavor profiles of soft and semisoft caprine milk cheeses was evaluated. Plain soft pasteurized milk cheeses were purchased from a grade A goat dairy and semisoft cheeses were made from pasteurized caprine milk at a university creamery on three separate occasions. Cheeses were assigned to one of four storage regimes: refrigeration (5C) for 30 days; freezing (−20C) for 24 h followed by thawing and refrigeration for 30 days; and frozen storage (−20C) for 3 or 6 months followed by thawing and refrigerated storage. Cheeses were sampled for sensory analysis initially (time 0 and initially after thawing) and subsequently across refrigerated storage. A descriptive sensory panel received 75 h of training on 13 terms for cheese flavor attributes and basic tastes from a previously adopted sensory lexicon for caprine milk cheeses. Cheeses were evaluated by each panelist in duplicate. Freezing and frozen storage had minimal effects on flavor properties of soft or semisoft cheeses (P > 0.05 for most attributes). Concurrent with previous instrumental studies, frozen storage appears to be a viable option for fresh soft caprine milk cheeses to maintain a year‐round supply.

Mexican Chihuahua Cheese: Sensory Profiles of Young Cheese

Sensory profiles of fresh semihard Chihuahua cheese produced in the northern Mexican state of Chihuahua were developed to characterize the flavors and textures of this traditionally made Hispanic-style cheese. Multiple allotments of Chihuahua cheese, 9 brands made with raw milk (RM) and 5 brands made with pasteurized milk (PM), were obtained within 3 d of manufacture from 12 different cheese plants throughout Chihuahua, México. Cheeses were shipped overnight to Wyndmoor, Pennsylvania, and flavor analyses were conducted within 14 to 18 d after manufacture. Four brands (2 RM and 2 PM cheeses) were then selected and multiple allotments were shipped at 3 distinct seasons over a 1-yr period for evaluation of flavor and texture. Microbial analysis was conducted prior to testing to ensure product safety. Descriptive analyses of cheese flavors and textures were conducted with panelists trained to use a universal or product-specific Spectrum intensity scale, respectively. Sensory profiles of cheeses varied among the different manufacturers. The most prominent flavor attributes were salty, sour, diacetyl, cooked, whey, bitter, and milk-fat. The RM cheeses had more intense sour, bitter, and prickle scores than the PM cheeses. Many cheese texture attributes were similar, but RM cheeses were perceived as softer than PM cheeses. As the demand for Hispanic-style cheeses increases, defining and understanding the sensory attributes of traditionally made Mexican cheeses provides guidance to cheese manufacturers as new ways are explored to improve the production and shelf life of the cheeses.

Texture and flavour development in Ras cheese made from raw and pasteurised milk

Texture, proteolysis and flavour development in Ras cheeses made from raw or pasteurised milk with two different thermophilic lactic cultures were monitored during ripening. Results showed that at day 1 of manufacture, the moisture content and pH were lower in raw milk cheese than in pasteurised milk cheeses. Levels of water-soluble nitrogen, casein breakdown, free amino groups and free fatty acids were higher in cheese made from raw milk than in that made from pasteurised milk. Textural characteristics, such as hardness, cohesiveness and chewines, increased in all treatments during the first 60 days of ripening due to the reduction in the moisture level during the second stage of salting (dry salting during the first 60 days of ripening). Cheese made from raw milk received the highest texture and flavour scores by panellists.

Proteolysis during ripening of Manchego cheese made from raw or pasteurized ewes' milk. Seasonal variation

Changes in nitrogen compounds during ripening of 40 batches of Manchego cheese made from raw milk (24 batches) or pasteurized milk (16 batches) at five different dairies throughout the year were investigated. After ripening for six months, degradation of p-kappa- and beta-caseins was more intense in raw milk cheese and degradation of alpha(s2)-casein in pasteurized milk cheese. Milk pasteurization had no significant effect on breakdown of alpha(s1)-casein. Hydrophobic peptide content did not differ between raw and pasteurized milk cheese, whereas hydrophilic peptide content was higher in raw milk cheese. There were no significant differences between seasons for residual caseins, but hydrophobic peptides were at a higher level in cheese made in autumn and winter and hydrophilic peptides in cheese made in winter and spring. Raw milk cheese had a higher content of total free amino acids and of most individual free amino acids than pasteurized milk cheese. The relative percentages of the individual free amino acids were significantly different for raw milk and pasteurized milk cheeses. The relative percentages of Lys and lie increased, while those of Val, Leu and Phe decreased during ripening. There were also seasonal variations within the relative percentages of free amino acids. In raw milk cheeses, Asp and Cys were relatively more abundant in those made in autumn, Glu and Arg in cheeses made in winter, and Lys and Ile in cheeses made in spring and summer. Biogenic amines were detected only in raw milk cheese, with the highest levels of histamine, tryptamine and tyramine in cheeses made in spring, winter and spring, respectively.

Characteristics of “Tetilla” pasteurized milk cheese manufactured with the addition of autochthonous cultures

Fourteen batches of Tetilla, a short-ripening cows-milk cheese produced in Galicia (NW Spain), were prepared from pasteurized milk inoculated with autochthonous cultures isolated from Tetilla raw milk cheeses. Two batches were made with an acid-aromatic starter containing Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. lactis var. diacetylactis strains. Twelve batches were made with the same lactococcal starter plus one of lactobacilli, leuconostoc, enterococci or micrococci strains. The microbiological, chemical, biochemical and sensory characteristics of the different batches were studied. Cheese batches made with micrococci strains showed greatest diversity, while cheese batches made with lactococci strains were the most homogeneous. Mean counts of aerobic mesophilic bacteria, lactic acid bacteria and citrate-fermented bacteria were similar in all cheese batches. Coliforms were only detected in five batches and Escherichia coli, Staphylococcus aureus, Listeria monocytogenes and Salmonella spp. were not detected. pH, total solids and fat contents agreed with the specifications of the Appellation of Origin of Tetilla cheese. Ash and protein contents were lower than those observed in Tetilla raw milk cheese. The mean degradation of β-casein in the cheese batches made with starter including lactobacilli was lower than in the remainder, while the degradation of α s1-casein was higher. These cheese batches and those manufactured with the addition of Leuconostoc showed the highest diacetyl-acetoin content. The most desirable sensorial characteristics were achieved in the batches elaborated with acid-aromatic starter with the addition of selected enterococci or micrococci strains.

Effect of Milk Pretreatment on the Keeping Quality of Domiati Cheese

2 Abstract: This study compared the usage of raw milk, heat treated milk and pasteurized milk in the manufacture of Egyptian soft Domiati cheese. The physico-chemical composition of the manufactured cheese was different. Soluble nitrogen, salt as well as pH values were high in raw milk cheese in comparison with the heat treated and pasteurized milk cheese. Considerable changes had occurred in raw milk cheese during the storage period more than heat treated and pasteurized milk cheese. The obtained results suggest that, pasteurization greatly improves the keeping quality of soft Domiati cheese and increase its shelf life.

Effect of dynamic high pressure on microbiological, rheological and microstructural quality of Cheddar cheese

The effect of high dynamic pressure treatment of milk (200 MPa for five 1-min cycles) on the viability of Listeria innocua and on the microbiological, textural and microstructural attributes of Cheddar cheese was investigated. Cheddar cheeses were made from: (A) pressurized whole milk, (B) pressurized skim milk which was standardized with pasteurized cream, (C) whole milk pasteurized at 72°C/15 s and (D) pressurized 2% fat milk. The fat contents of milk batches subjected to treatments A–C were standardized to 3.4%. All milks were contaminated with L. innocua at levels of 10 5 –10 6 colony forming units (cfu) mL −1 . Pressurization of milk resulted in a three- to four- log cycle reduction of L. innocua cfu and remarkable reductions in casein micelle and fat globule sizes. Cheeses made from pressurized milk retained more moisture and protein and produced higher yield than those from pasteurized milk. Rheological measurements revealed that A- and D-cheese were more firm, elastic and cohesive and less brittle than pasteurized milk cheese. These cheeses developed, as observed by transmission electron microscopy, a very compact protein matrix in which large numbers of very small fat globules were emulsified. Meanwhile, cheese from milk subjected to treatment B exhibited texture, behaviour and structural characteristics close to those of pasteurized milk cheese. The structural characteristics of pressurized milk cheeses reported in this study indicated the possibility of developing a variety of dairy products with varying functional properties.

Effect of Phage on Survival of Salmonella Enteritidis during Manufacture and Storage of Cheddar Cheese Made from Raw and Pasteurized Milk

The ability of Salmonella Enteritidis to survive in the presence of phage, SJ2, during manufacture, ripening, and storage of Cheddar cheese produced from raw and pasteurized milk was investigated. Raw milk and pasteurized milk were inoculated to contain 104 CFU/ml of a luminescent strain of Salmonella Enteritidis (lux) and 108 PFU/ml SJ2 phage. The milks were processed into Cheddar cheese following standard procedures. Cheese samples were examined for Salmonella Enteritidis (lux), lactic acid bacteria, molds and yeasts, coliforms, and total counts, while moisture, fat, salt, and pH values were also measured. Salmonella Enteritidis (lux) was enumerated in duplicate samples by surface plating on MacConkey novobiocin agar. Bioluminescent colonies of Salmonella Enteritidis were identified in the NightOwl molecular imager. Samples were taken over a period of 99 days. Counts of Salmonella Enteritidis (lux) decreased by 1 to 2 log cycles in raw and pasteurized milk cheeses made from milk containing phage. In cheeses made from milks to which phage was not added, there was an increase in Salmonella counts of about 1 log cycle. Lower counts of Salmonella Enteritidis (lux) were observed after 24 h in pasteurized milk cheese containing phage compared to Salmonella counts in raw milk cheese with phage. Salmonella Enteritidis (lux) survived in raw milk and pasteurized milk cheese without phage, reaching a final concentration of 103 CFU/g after 99 days of storage at 8°C. Salmonella did not survive in pasteurized milk cheese after 89 days in the presence of phage. However, Salmonella counts of approximately 50 CFU/g were observed in raw milk cheese containing phage even after 99 days of storage. In conclusion, this study demonstrates that the addition of phage may be a useful adjunct to reduce the ability of Salmonella to survive in Cheddar cheese made from both raw and pasteurized milk.

Effect of technological parameters on the characteristics of kasseri cheese made from raw or pasteurized ewes’ milk

Two groups of kasseri cheese (pasta filata type) were manufactured from raw or pasteurized ewes’ milk, without starter cultures. Cheeses of each group were divided into two subgroups: the first was ripened and stored at 4°C and packaged in plastic film; the second ripened and stored at 15°C and coated with paraffin wax. Milk pasteurization and technological parameters had a significant effect on the pH ( P < 0.05), while only technological parameters had an effect on the total solids content. At day 120, the range of mean cfu/g counts for the mesophilic aerobic flora was 9.5 × 107−1.4 × 108; for the thermophilic streptococci, the range was 2.6 × 107−7.6 × 107; and for the thermophilic bacilli, 9.8 × 106−1.7 × 107. Changes in the N fractions became significant after 30 days of ripening. For mature 120‐day‐old cheeses, the percentage of total N soluble at pH 4.6 was 22.7%–22.9% in raw milk cheeses and 19.0%–21.7% in pasteurized milk cheeses. The percentage of total N soluble at 12% TCA was 10.1%–12.2% in raw milk cheeses and 7.3%–11.5% in pasteurized milk cheeses; the percentages of total N soluble at 5% PTA were 3.1%–4.0% and 2.6%–3.6%, respectively. The residual αs‐casein percentages at day 120 ranged between 63% and 78% of the respective area at day 1; the residual β‐casein ranged between 67% and 75%. There were some characteristic differences in the reverse phase‐HPLC peptide profiles of the four cheeses. In general, the effect of the different ripening conditions was more pronounced in cheeses made from pasteurized milk.

A large outbreak of Shigella sonnei gastroenteritis associated with consumption of fresh pasteurised milk cheese.

A large outbreak of Shigella sonnei gastroenteritis occurred in Murcia Region (Southeast Spain) in the winter of 1995-1996. More than 200 people were affected. Epidemiological investigations implicated a regionally manufactured fresh pasteurised milk cheese as the vehicle of infection. A case-control study showed a statistically significant association between the illness and consumption of the suspect cheese. The dispersed sale of the cheese resulted in a regional dissemination of the organism and people were affected in eight townships. Research suggested that an infected foodhandler at the cheese factory might have been the source of contamination and that the processing method might have allowed cross-contamination to occur. This study emphasises the importance of increasing the control of strict hygiene during the processing of fresh cheese, since legislation does not forbid direct contact by hand that could result in contamination of cheese even when the milk pasteurisation process was correctly performed.

Effect of milk pasteurization on lipolysis during ripening of ovine cheese manufactured at different times of the year

Lipolysis was studied in cheeses manufactured with pasteurized and raw ovine milk with a starter culture added in winter, spring and summer, up to 180 d of ripening. Pasteurized milk cheeses had significantly lower levels of lipolysis than raw milk cheeses in winter after 180 d of ripening and in spring both after 90 and 180 d of ripening. The relative amounts of individual FFA after 180 d of ripening changed from winter to summer, both in pasteurized and in raw milk cheeses. In pasteurized milk cheeses made in winter the predominant FFA were C18:1 (2152 ∠ 386 μmol.kg -1 ), C4 (1 954 ∠ 354 μmol.kg -1 ), C16 (1 541 ∠ 406 μmol.kg -1 ) and C10 (1 452 ∠ 188 μmol.kg -1 ). In con- trast, in pasteurized milk cheeses made in summer C16 (2860 ∠ 1305 μmol.kg -1 ) and C18:1 (2677 ∠ 973 μmol.kg -1 ) were the major FFA. The percent FFA composition of both types of cheeses changed during ripening: short-chain (C4 to C10) FFA increased from approximately 25% to approximately 40 to 45%, whereas long chain (♢ C16:0) FFA decreased from approximately 55% to approximately 40 to 45% in winter and spring. However, in both types of cheese made in summer long chain FFA represented 52% and volatile FFA represented approximately 28 to 32% of the total after 180 ripen- ing days. Milk pasteurization reduced the levels of acetic acid by 99% after 90 ripening days at the three times of the year studied.

Characteristics of Manchego Cheese Manufactured from Raw and Pasteurized Ovine Milk and with Defined-Strain or Commercial Mixed-Strain Starter Cultures

Microbiological, chemical, rheological, and sensory characteristics of Manchego cheese manufactured with raw or pasteurized milk and with a defined-strain starter culture made up of four Lactococcus lactis ssp. lactis isolates from high quality artisanal Manchego cheese have been compared with those of cheese made with a commercial mixed-strain starter culture. Higher total viable counts and lower pH values after 24 h were detected in both raw and pasteurized milk cheeses made with the defined-strain starter culture, which survived better than did the commercial mixed-strain starter culture during ripening of pasteurized milk cheese. Differences in proteolysis of raw milk cheeses were reduced, whereas lower concentrations of residual caseins and higher concentrations of pH 4.6-soluble N and TCA-soluble N were observed in pasteurized milk cheeses made with the commercial mixed-strain starter culture. Elasticity, fracturability, and hardness were higher in raw and pasteurized milk cheeses made with the defined-strain starter culture. Flavor quality and intensity were not apparently affected by the starter culture used, whereas cheese bitterness was lower in raw and in pasteurized milk cheeses made with the defined-strain starter culture.