Effect of high-pressure treatment of ewe raw milk curd at 200 and 300 MPa on characteristics of Hispánico cheese

Hispánico cheese is a semihard variety made from a mixture of cow and ewe milks. Production of ewe milk declines in summer and autumn. To surmount the seasonal shortage of ewe milk and prevent the inactivation of milk enzymes by pasteurization, curd made in spring from ewe raw milk was pressurized at 200 and 300 MPa and stored frozen for 4 mo. Thawed ewe milk curds were added to fresh curd made from pasteurized cow milk for the manufacture of experimental Hispánico cheeses. Control cheese was made from a mixture of pasteurized cow and ewe milk in the same proportions as those used for experimental cheeses. Experimental cheeses exhibited lower dry matter content, higher aminopeptidase activity and total free amino acid concentration, and higher levels of acetic and propionic acids, aldehydes, alcohols, and esters compared with control cheese. In contrast, the concentration of total free fatty acids and ketones and the levels of textural parameters were significantly higher in control cheese. The use of ewe raw milk curd pressurized at 200 and 300 MPa, stored frozen and thawed for Hispánico cheese manufacture, was generally beneficial for cheese characteristics and increased cheese yield because of the lower dry matter content of experimental cheeses.     

Microbiological,chemical, textural and sensory characteristics of Hispánico cheese manufactured using frozen ovine milk curds scalded at different temperatures

Hispánico cheese is a semi-hard variety, manufactured in Spain from a mixture of pasteurized bovine and ovine milk. To study one strategy for overcoming a seasonal shortage of ovine milk in summer and autumn, curds made from ovine milk, scalded at 32, 35 or 38 °C, were pressed for 30 min and frozen at ?24 °C for 4 months. After thawing, they were added to fresh bovine milk curd for the manufacture of experimental Hispánico cheeses. Control cheese was made from a mixture of pasteurized bovine and ovine milk in the same (80:20) proportion. No significant effect of the addition of frozen ovine milk curd or scalding temperature was found for lactic acid bacteria counts, dry matter content, hydrophilic and hydrophobic peptides, 45 out of 65 volatile compounds, texture, and sensory characteristics throughout a 60-day ripening period. Differences between cheeses, of low magnitude and little practical significance, were found for pH value, aminopeptidase activity, proteolysis, free amino acids, free fatty acids, and the remaining 20 volatile compounds. Thus, the addition of frozen ovine milk curd to fresh bovine milk curd does not alter the main physicochemical and sensory characteristics of Hispánico cheese.     

Effect of high-pressure treatment and a bacteriocin-producing lactic culture on the proteolysis, texture, and taste of Hispánico cheese

The effects of high-pressure treatment, by itself or in combination with a bacteriocin-producing culture added to milk, on the proteolysis, texture, and taste of Hispánico cheese were investigated. Two vats of cheese were manufactured from a mixture of cow and ewe milk. Milk in one vat was inoculated with 0.5% Lactococcus lactis ssp. lactis INIA 415, a nisin Z and lacticin 481 producer; 0.5% L. lactis ssp. lactis INIA 415-2, a bacteriocin-nonproducing mutant; and 2% of a commercial Streptococcus thermophilus culture. Milk in the other vat was inoculated with 1% L. lactis ssp. lactis INIA 415-2 and 2% S. thermophilus culture. After ripening for 15 d at 12°C, half of the cheeses from each vat were treated at 400 MPa for 5 min at 10°C. Ripening of high-pressure-treated and untreated cheeses continued at 12°C until d 50. High-pressure treatment of cheese made from milk without the bacteriocin producer accelerated casein degradation and increased the free AA content, but it did not significantly influence the taste quality or taste intensity of the cheese. Addition of the bacteriocin producer to milk lowered the ratio of hydrophobic peptides to hydrophilic peptides, increased the free AA content, and enhanced the taste intensity. The combination of milk inoculation with the bacteriocin producer and high-pressure treatment of the cheese resulted in higher levels of both hydrophobic and hydrophilic peptides but had no significant effect on the free AA content, taste quality, or taste intensity.     

Short communication: Occurrence of aflatoxin M1 in the Manchego cheese supply chain

The importance of ewe milk lies in the production of high quality cheeses, such as Manchego cheese with a Protected Designation of Origin, whose safety must be guaranteed. In a 2-yr study, 407 bulk tank milk samples from farms and 82 silo milk and curd samples from cheese factories were collected from southeast Spain and tested for aflatoxin M1 (AFM1) using 2 commercial ELISA tests. Of these, 99.3% of the bulk tank samples had AFM1 levels below the European Union (EU) legal limit for milk (50 ng/kg), and well below the limit adopted by the Codex Alimentarius (500 ng/kg). Moreover, 98.8% of the silo milk and curd samples from cheese factories had AFM1 levels below the EU limit for milk. When considering median AFM1 concentrations, an average 4-fold increase was found in the final curd in relation to the corresponding silo milk. Control of AFM1 in Manchega ewe milk would enhance dairy product safety by the possible detection of faults in the manufacture of Manchego cheese.     

High-Pressure Treatment and Freezing of Raw Goat Milk Curd for Cheese Manufacture: Effects on Cheese Characteristics

High-pressure treatment of raw goat milk curd was investigated as an alternative to thermal treatment of milk in cheese manufacture, and curd freezing as a procedure to surmount the seasonality of goat milk production. Experimental cheeses were made by mixing (70:30) fresh cow milk curd with frozen curd from pasteurized goat milk (PGC), frozen curd from raw goat milk (RGC), or frozen pressurized curd from raw goat milk (PRGC). Control cheese was made from a mixture (70:30) of pasteurized cow and goat milk. RGC cheese showed the highest counts of staphylococci, Gram-negative bacteria and coliforms, whereas PRGC cheese had maximum aminopeptidase activity, esterase activity, and overall proteolysis. Control cheese exhibited the highest dry matter content and peptide levels, the lowest concentration of free amino acids, the highest concentration of volatile compounds such as free fatty acids, alcohols and esters, and the firmest texture. Differences in sensory characteristics between experimental and control cheeses were of minor importance. High-pressure treatment of curd allowed the production of cheese of bacteriological quality similar to that of control cheese made using pasteurized milk, while curd freezing did not alter the sensory characteristics of experimental cheeses with respect to control cheese.     

Microbial dynamics during the ripening of a mixed cow and goat milk cheese manufactured using frozen goat milk curd

To overcome the seasonal shortage of goat milk in mixed milk cheese manufacture, pasteurized goat milk curd and high-pressure-treated raw goat milk curd manufactured in the spring were held at −24°C for 4 mo, thawed, and mixed with fresh cow milk curd for the manufacture of experimental cheeses. Control cheeses were made from a mixture of pasteurized cow and goat milk. The microbiota of experimental and control cheeses was studied using culture-dependent and culture-independent techniques. Bacterial enumeration by classical methods showed lactic acid bacteria to be the dominant population in both control and experimental cheeses. In total, 681 isolates were grouped by partial amplified rDNA restriction analysis (ARDRA) into 4 groups and identified by 16S rRNA gene sequencing as Lactococcus lactis ssp. lactis (563 isolates), Leuconostoc pseudomesenteroides (72 isolates), Lactobacillus spp. (34 isolates), and Lc. lactis ssp. cremoris (12 isolates). Temporal temperature gradient gel electrophoresis (TTGE) analysis of cheese showed (1) the predominance of Lc. lactis in all cheeses; (2) the presence of Leu. pseudomesenteroides population in all cheeses from d 15 onward; (3) the presence of a Lactobacillus plantarum population in control cheese until d 15 and in experimental cheeses throughout the ripening period. Due to the most diverse and complete set of peptidases present in the genus Lactobacillus, the prevalence of this population in experimental cheeses could give rise to differences in cheese flavor between experimental and control cheeses.     

Study of the chemical composition,proteolysis, volatile compounds,and textural properties of industrial and traditional Beaten (Bieno sirenje) ewe milk cheese

The objective of this study was to determine the gross composition, proteolysis, and volatile and texture profiles during ripening of industrial (IND) and traditional (TRD) Beaten (Bieno sirenje) cheeses made by using ewe milk. In the course of the analyses, statistical differences were determined in some physicochemical parameters, nitrogen fractions, and total free amino acid levels between TRD and IND types of cheese. Higher levels of proteolysis were observed in IND cheeses than in TRD cheeses during ripening. Levels of residual β- and α_s-caseins were 72.2 and 48.7%, respectively, in 180-d-old TRD cheeses. However, the residual levels were 52.8% for β-casein and 18% for α_s-casein in IND cheeses. Similar differences were noted for the reversed-phase HPLC peptide profiles of 2 types of cheeses. Also, higher concentrations of peptides were eluted in IND cheeses than in TRD cheeses during ripening. A total of 73 volatile compounds, including alcohols (16), esters (17), acids (14), terpenes (7), ketones (5), aldehydes (4), and miscellaneous (10) were identified. The IND cheeses contained higher levels of carboxylic acids, esters, alcohols, and terpenes than the TRD cheeses; however, the same levels of methyl ketones were determined in the 2 types of cheeses at the end of ripening. These may be due to some differences (e.g., pasteurization and scalding temperature, among other factors) in the manufacture of the 2 types of Beaten cheeses. The textural profile of Beaten cheeses showed that TRD production method resulted in firmer, less fracturable, and stiffer cheeses than the IND production method. In conclusion, the results suggest that the use of industrial production method (pasteurization of cheese milk and curd scalding at 70°C) in the manufacture of Beaten ewe milk cheese enriched the volatile profile of the cheese.     

Detection of milk powder and caseinates in Halloumi cheese

Halloumi cheese is traditionally manufactured from fresh milk. Nevertheless, dried dairy ingredients are sometimes illegally added to increase cheese yield. Lysinoalanine and furosine are newly formed molecules generated by heating and drying milk protein components. The levels of these molecular markers in the finished Halloumi have been investigated to verify their suitability to reveal the addition of skim milk powder and calcium caseinate to cheese milk. Because of the severe heating conditions applied in curd cooking, genuine Halloumi cheeses (n = 35), representative of the Cyprus production, were characterized by levels of lysinoalanine (mean value = 8.1 mg/100 g of protein) and furosine (mean value = 123 mg/100 g of protein) unusual for natural cheeses. Despite the variability of the values, a good correlation between the 2 parameters (R = 0.975) has been found in all cheeses, considering both the fresh and mature cheeses as well as those obtained from curd submitted to a prolonged cooking following a traditional practice adopted by a very small number of manufacturers. Experimental cheeses made by adding as low as 5% of skim milk powder, or calcium caseinate, or both, to cheese milk fell outside the prediction limits at ±2 standard deviation of the above-reported correlation regardless of curd cooking conditions or ripening length. This correlation may be adopted as a reliable index of Halloumi cheese genuineness.     

Microstructural, Textural and Colour Characteristics During Ripening of Hispánico Cheese Made Using High-Pressure-Treated Ovine Milk Curd

High-pressure (HP) treatment of curd at low temperatures, on top of efficiently reducing microbial loads while maintaining most of the enzymatic activity, can be useful to overcome the seasonal shortage in ovine milk production. In this work, raw ovine milk curds were subjected to a wide range of HP treatments and, after frozen storage, used in the manufacture of Hispánico cheese. Confocal scanning laser microscopy of HP-treated curds showed increasing denser and more compact protein networks with the pressure applied. Although no differences in overall porosity were recorded between HP-treated and non-pressurised curds, HP treatment lowered pore number and modified pore size and shape. Whereas confocal scanning laser microscopy of control cheese showed open structures with numerous and irregular cavities, additional highly compact protein network areas could be observed in experimental cheeses micrographs. These differences trailed off with time and were no longer observed after 60 days of ripening. Experimental cheeses had significantly lower dry matter values than control cheese, and higher proteolytic indexes. Their texture was less firm than that of control cheese throughout the whole ripening period, requiring less force to be broken and deformed. Experimental cheeses showed lower lightness values than control cheese after 30 days of ripening, but no differences were found after 60 days. Our results indicate that frozen storage of HP-treated curds from ovine milk is a viable option for the production of Hispánico cheese.     

Triacylglycerol composition of protected designation of origin cheeses during ripening. Authenticity of milk fat

Triacylglycerol (TAG) composition by carbon number in 2 protected designation of origin cheeses, Mahón (cheese from cow milk) and Manchego (cheese from ewe milk) that were manufactured by 3 different producers was analyzed during cheese ripening using gas chromatography with a short capillary column. The TAG composition at different times during cheese ripening was also analyzed in cheeses from different batches produced at the same plant. Lipolysis levels in the Mahón and Manchego cheeses during ripening were low; free fatty acid values ranged from 2,500 to 4,000 ppm at the end of ripening. The TAG composition did not change significantly during ripening. The TAG values obtained from each cheese sample were substituted into the multiple regression equations that have been proposed to detect foreign fats in milk fat. The values obtained using the equations for bovine (proposed by the European Union) and ovine milk (proposed by our laboratory) were within the normal range. Accordingly, these equations can be considered useful for detecting foreign fat in these cheeses during the ripening period contemplated during this study.     

Nutritional and sensory characteristics of Minas fresh cheese made with goat milk,cow milk,or a mixture of both

This study aimed to assess and compare the nutritional, technological, and sensory characteristics of Minas fresh cheese made with goat milk, cow milk, or a mixture of the two stored in cold conditions for 21 d. The yield and centesimal composition of the cheeses were not affected by the type of milk used in their preparation. Reductions were observed in the moisture content, pH, proteolysis index, and instrumental hardness; moreover, increases were observed in the syneresis, acidity index, and depth of proteolysis index in all cheeses. The percentages of caprylic, capric, oleic, and linoleic fatty acids were higher in goat milk cheese and cheese made with a mixture of goat and cow milk compared with cow milk cheese, and a sensory evaluation revealed differences in color, flavor, and aroma between the cheeses. The preparation of Minas fresh cheese with a mixture of goat and cow milk can be a viable alternative for dairy products in the market that can be characterized as high-quality products that meet consumer demands.     

Interlaboratory validation of two multiplex quantitative real-time PCR methods to determine species DNA of cow, sheep and goat as a measure of milk proportions in cheese

Milk products like yogurt, flavoured milk-drinks, curd and cheese may be composed of milk different from cow, namely of ruminant species like sheep and goat. Such products experience an increasing demand in Europe and are recognised as healthy and naturally finished specialities. To verify declared milk compositions in these dairy products, two different quantitative multiplex PCR systems have been evaluated in a comparison test with eleven participating laboratories employing two unknown, traditionally manufactured cheeses with different degrees of ripening to determine milk fractions from cow, ewe and goat. Precision and accuracy was investigated by calibration to dilutions of DNA mixtures and to homologous matrix-adapted reference cheeses, respectively. As expected, independent of the particular method, best inter- and intra-laboratory accuracy has been achieved through the use of homologous reference cheese standards. Furthermore, it has been shown that cheese ripening and the concomitant DNA degradation exert an inverse effect on the method’s sensitivity and performance characteristics. Additionally, a broad market survey of different milk products demonstrated its applicability as an efficient analytical tool for food control laboratories to challenge the authenticity of milk and its products from small ruminants.     

Effect of β-lactoglobulin A and B whey protein variants on cheese yield potential of a model milk system

Cheese yield mainly depends on the amount and proportion of milk constituents; however, genetic variants of the proteins present in milk may also have an important effect. The objective of this research was to study the effect of the variants A and B of β-lactoglobulin (LG) on cheese yield using a model system consisting of skim milk powder fortified with different levels of a mixture containing α-lactalbumin and β-LG genetic variants (A, B, or A-B) in a 1:2 ratio. Fortified milk samples were subjected to pasteurization at 65°C for 30 min. Miniature cheeses were made by acidifying (pH = 5.9) fortified milk and incubating with rennet for 1 h at 32°C. The clot formed was cut, centrifuged at 2,600 × g for 30 min at 20°C and drained for determining cheese yield. Cheese-yielding capacity was expressed as actual yield (grams of cheese curd per 100 g of milk) and dry weight yield (grams of dried cheese curd per 100 g of milk). Free-zone capillary electrophoresis was used for determining β-LG A or B recovery in the curd during rennet-induced coagulation. The presence of β-LG variant B resulted in a significantly higher actual and dried weight cheese yield than when A or A-B were present at levels ≤0.675% of whey protein (WP) addition. Results of free-zone capillary electrophoresis allowed us to infer that β-LG B associates with the casein micelles during renneting, as shown by an increase in the recovery of this variant in the curd when β-LG B was added up to a maximum at 0.45% (equivalent to 0.675% WP). In general, actual or dried weight cheese yield increased as WP addition was increased from 0.225 to 0.675%. However, when WP addition ranged from 0.675 to 0.90%, a drastic drop in cheese yield was observed. This behavior may be because an increase in the aggregation of casein micelles with a concomitant inclusion of whey protein in the gel occurs at low levels of WP addition, whereas once the association of WP with the casein micelles reach a saturation point at addition levels higher than 0.675%, rearrangements of the gel network result in larger whey expulsion and syneresis. This knowledge is expected to be useful to maximize cheese yield and optimize processing conditions during cheese and cheese analogs manufacturing.     

Short communication: Norbixin and bixin partitioning in Cheddar cheese and whey

The Cheddar cheese colorant annatto is present in whey and must be removed by bleaching. Chemical bleaching negatively affects the flavor of dried whey ingredients, which has established a need for a better understanding of the primary colorant in annatto, norbixin, along with cheese color alternatives. The objective of this study was to determine norbixin partitioning in cheese and whey from full-fat and fat-free Cheddar cheese and to determine the viability of bixin, the nonpolar form of norbixin, as an alternative Cheddar cheese colorant. Full-fat and fat-free Cheddar cheeses and wheys were manufactured from colored pasteurized milk. Three norbixin (4% wt/vol) levels (7.5, 15, and 30 mL of annatto/454 kg of milk) were used for full-fat Cheddar cheese manufacture, and 1 norbixin level was evaluated in fat-free Cheddar cheese (15 mL of annatto/454 kg of milk). For bixin incorporation, pasteurized whole milk was cooled to 55°C, and then 60 mL of bixin/454 kg of milk (3.8% wt/vol bixin) was added and the milk homogenized (single stage, 8 MPa). Milk with no colorant and milk with norbixin at 15 mL/454 kg of milk were processed analogously as controls. No difference was found between the norbixin partition levels of full-fat and fat-free cheese and whey (cheese mean: 79%, whey: 11.2%). In contrast to norbixin recovery (9.3% in whey, 80% in cheese), 1.3% of added bixin to cheese milk was recovered in the homogenized, unseparated cheese whey, concurrent with higher recoveries of bixin in cheese (94.5%). These results indicate that fat content has no effect on norbixin binding or entrapment in Cheddar cheese and that bixin may be a viable alternative colorant to norbixin in the dairy industry.     

Improving the yield of Mozzarella cheese by phospholipase treatment of milk

Part-skim Mozzarella cheese was manufactured from milk hydrolyzed with fungal phospholipase A₁ prior to renneting. The phospholipase treatment reduced fat losses in whey and cooking water and increased cheese yield as a result of improved fat and moisture retention in the cheese curd. The amount of phospholipids in the whey was reduced because of improved retention of lysophospholipids in the cheese curd. Water binding in the fresh curds and young cheeses up to 3 wk of storage was investigated by a ¹H nuclear magnetic resonance spin-spin relaxation technique. In the fresh curds, 2 dominant water fractions were present, characterized by average spin-spin relaxation times (T₂) of 14 and 86 to 89 ms, respectively. These 2 fractions of low- and high-molecular-mobility water were similar in all cheeses and presumed to represent water associated with the casein matrix and water present in the pores. A few hours after manufacture, cheeses made with phospholipase showed decreased T₂ of the high-mobility fraction, indicating improved water-holding capacity. It is suggested that lysophospholipids released from the fat globule membranes act as surface-active agents in the cheese curd, helping emulsification of water and fat during processing and reducing syneresis. During 3 wk of storage after manufacture, the mobility of both water fractions increased in all cheeses, but was highest in the cheeses made with phospholipase. The increase in mobility during the first weeks of storage has earlier been ascribed to structural changes in the protein matrix, which in principle could be accelerated because of the higher moisture content. However, the microstructure of phospholipase-treated cheese was investigated by confocal laser scanning microscopy and found to be very similar to the control cheese during processing and up to 28 d of storage. In addition, flowability, stretchability, and browning were acceptable and similar in all the manufactured cheeses. Thus, phospholipase hydrolysis of cheese milk improved the cheese yield without changing the cheese microstructure, and resulted in cheese with functional properties that were identical to traditional Mozzarella cheese.     

Yield, composition and rheological characteristics of cheddar cheese made with high pressure processed milk

High Pressure (HP) treatment of milk prior to cheese-making was shown to increase the yield of cheese due to increased protein and moisture retention in cheese. Cheeses were made with raw milk or milk treated with high temperature short-time (HTST) pasteurization, and HP treatments at two levels (483 and 676 MPa) at 10 °C, 483 MPa HP at 30 °C, and 483 MPa HP at 40 °C. Cheese yield, total solids, protein, fat and salt contents were evaluated, and fat and protein recovery indices were calculated. Cheeses from HP treatments of 676 MPa at 10 °C and 483 MPa at 30 °C exhibited wet yields of 11.40% and 11.54%, respectively. Protein recovery was 79.9% for HP treatment of 676 MPa at 10 °C. The use of slightly higher pressurization temperatures increased moisture retention in cheese. Visco-elasticity of cheeses was determined by dynamic oscillatory testing and a creep-recovery test. Rheological parameters such as loss (G″) and storage (G′) moduli were dependent on oscillation frequency. At high (173 rad/s) and low (2.75 rad/s) angular frequencies, cheeses made from milk treated at 483 MPa at 10 °C behaved more solid-like than other treatments. Creep tests indicated that cheeses from milk treated with 483 MPa HP at 10 °C showed the smallest instantaneous compliance (J_o), confirming the more solid-like behavior of cheese from the 483 MPa at 10 °C treatment compared to the behavior of cheeses from other treatments. Cheeses made with pasteurized milk were more deformable, exhibited less solid-like behavior than cheeses made with HP treated milk, as shown by the J_o value. With more research into bacteriological implications, HP treatment of raw milk can augment Cheddar cheese yield with better curd formation properties.     

Improvement in melting and baking properties of low-fat Mozzarella cheese

Low-fat cheeses dehydrate too quickly when baked in a forced air convection oven, preventing proper melting on a pizza. To overcome this problem, low-fat Mozzarella cheese was developed in which fat is released onto the cheese surface during baking to prevent excessive dehydration. Low-fat Mozzarella cheese curd was made with target fat contents of 15, 30, 45, and 60 g/kg using direct acidification of the milk to pH 5.9 before renneting. The 4 portions of cheese curd were comminuted and then mixed with sufficient glucono-δ-lactone and melted butter (45, 30, 15, or 0 g/kg, respectively), then pressed into blocks to produce low-fat Mozzarella cheese with about 6% fat and pH 5.2. The cheeses were analyzed after 15, 30, 60, and 120 d of storage at 5°C for melting characteristics, texture, free oil content, dehydration performance, and stretch when baked on a pizza at 250°C for 6 min in a convection oven. Cheeses made with added butter had higher stretchability compared with the control cheese. Melting characteristics also improved in contrast to the control cheese, which remained in the form of shreds during baking and lacked proper melting. The cheeses made with added butter had higher free oil content, which correlated (R² ≥ 0.92) to the amount of butterfat added, and less hardness and gumminess compared with the control low fat cheese.     

Sensory analysis and species-specific PCR detect bovine milk adulteration of frescal (fresh) goat cheese

The Brazilian market for dairy products made from goat milk is increasing despite the seasonality of production and naturally small milk production per animal, factors that result in high-priced products and encourage fraud. In Brazil, no official analytical method exists for detecting adulteration of goat dairy products with cow milk. The aim of this study was to design a strategy to investigate the adulteration of frescal (fresh) goat cheeses available in the Rio de Janeiro retail market, combining analysis of cheese composition and the perception of adulteration by consumers. Commercial goat cheeses were tested by using a duplex PCR assay previously designed to authenticate cheeses, by targeting the mitochondrial 12S ribosomal RNA genes of both species simultaneously. The PCR test was able to detect 0.5% (vol/vol) cow milk added during goat cheese formulation. The analysis of 20 locally produced goat cheeses (20 lots of 4 brands) showed that all were adulterated with cow milk, even though the labels did not indicate the addition of cow milk. To estimate the ability of consumers to perceive the fraudulent addition of cow milk, a triangle test was performed, in which cheeses formulated with several different proportions of goat and cow milk were offered to 102 regular consumers of cheese. Detection threshold analysis indicated that almost half of the consumers were able to perceive adulteration at 10% (vol/vol) cow milk. Effective actions must be implemented to regulate the market for goat dairy products in Brazil, considering the rights and choices of consumers with respect to their particular requirements for diet and health, preference, and cost.     

Rheology and melt characterization of low-fat and full fat Mozzarella cheese made from microfluidized milk

Microfluidization of cheese milk at different temperatures and pressures altered the meltability and rheological properties of Mozzarella cheese. Pasteurized milks, standardized to 1.0 (low-fat (LF)) or 3.2 (full fat (FF)) g fat/100 g milk, heated to 10, 43, or 54 °C, and then microfluidized at pressures of 34, 103, or 172 MPa, were used to manufacture Mozzarella cheese. Cheeses made from nonmicrofluidized milks served as controls. During the hot water step, only control cheeses and cheeses made with milk microfluidized at 10 °C could be stretched while all others had short curds that did not fuse together. Cheese responses to different stresses (heat, compression, torsion, and oscillatory shear) were measured after 1 and 6 weeks of storage. FF cheeses made with the control milks and milks processed at 10 °C/34 MPa or 10 °C/103 MPa were softer and less rigid, and had the lowest visco-elastic properties and the highest meltabilities of all the cheeses. Microfluidization of the cheese milk did not improve the melt or rheology of LF cheeses. Microfluidization of milk with fat in the liquid state at higher pressures resulted in smaller lipid droplets that altered the component interactions during the formation of the cheese matrix and resulted in LF and FF Mozzarella cheeses with poor melt and altered rheology.