Low-moisture part-skim mozzarella cheese made from blends of camel and bovine milk: Gross composition,proteolysis, functionality,microstructure, and rheological properties

Camel (CM) milk is used in variety of ways; however, it has inferior gelling properties compared with bovine milk (BM). In this study, we aimed to investigate the physicochemical, functional, microstructural, and rheological properties of low-moisture part-skim (LMPS) mozzarella cheese, made from BM, or BM mixed with 15% CM (CM15%) or 30% CM (CM30%), at various time points (up to 60 d) of storage at 4°C after manufacture. Low-moisture part-skim mozzarella cheeses using CM15% and CM30% had high moisture and total Ca contents, but lower soluble Ca content. Compared with BM cheese, CM15% and CM30% LMPS mozzarella cheese exhibited higher proteolysis rates during storage. Adding CM affected the color properties of LMPS mozzarella cheese manufactured from mixed milk. Scanning electron microscopy images showed that the microstructure of CM15% and CM30% cheeses had smooth surfaces, whereas the BM cheese microstructures were rough with granulated surfaces. Low-moisture part-skim mozzarella cheeses using CM15% and CM30% showed significantly lower hardness and chewiness, but higher stringiness than BM cheese. Compared with BM cheese, CM15% and CM30% cheeses showed lower tan δ levels during temperature surges, suggesting that the addition of CM increased the meltability of LMPS mozzarella cheese during temperature increases. Camel milk addition affected the physicochemical, microstructural, and rheological properties of LMPS mozzarella cheese.     

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.     

Effect of camel chymosin on the texture,functionality, and sensory properties of low-moisture,part-skim Mozzarella cheese

The objective of this study was to compare the effect of coagulant (bovine calf chymosin, BCC, or camel chymosin, CC), on the functional and sensory properties and performance shelf-life of low-moisture, part-skim (LMPS) Mozzarella. Both chymosins were used at 2 levels [0.05 and 0.037 international milk clotting units (IMCU)/mL], and clotting temperature was varied to achieve similar gelation times for each treatment (as this also affects cheese properties). Functionality was assessed at various cheese ages using dynamic low-amplitude oscillatory rheology and performance of baked cheese on pizza. Cheese composition was not significantly different between treatments. The level of total calcium or insoluble (INSOL) calcium did not differ significantly among the cheeses initially or during ripening. Proteolysis in cheese made with BCC was higher than in cheeses made with CC. At 84 d of ripening, maximum loss tangent values were not significantly different in the cheeses, suggesting that these cheeses had similar melt characteristics. After 14 d of cheese ripening, the crossover temperature (loss tangent = 1 or melting temperature) was higher when CC was used as coagulant. This was due to lower proteolysis in the CC cheeses compared with those made with BCC because the pH and INSOL calcium levels were similar in all cheeses. Cheeses made with CC maintained higher hardness values over 84 d of ripening compared with BCC and maintained higher sensory firmness values and adhesiveness of mass scores during ripening. When melted on pizzas, cheese made with CC had lower blister quantity and the cheeses were firmer and chewier. Because the 2 types of cheeses had similar moisture contents, pH values, and INSOL Ca levels, differences in proteolysis were responsible for the firmer and chewier texture of CC cheeses. When cheese performance on baked pizza was analyzed, properties such as blister quantity, strand thickness, hardness, and chewiness were maintained for a longer ripening time than cheeses made with BCC, indicating that use of CC could help to extend the performance shelf-life of LMPS Mozzarella.     

Pressing technique and its effect on the quality of Dhaka cheese

Dhaka cheese is a semihard artisanal variety made mainly from bovine milk, using very simple pressing methods. Experimental cheeses were pressed at gauge pressures up to 31 kPa for 12 h at 24 °C and 70% RH. These cheeses were subsequently examined for their compositional, textural and rheological properties plus their microstructures investigated by confocal laser microscopy. The cheese pressed at 15.6 kPa was found to have the best compositional and structural properties.     

Linear Viscoelastic Properties of Regular- and Reduced-Fat Pasteurized Process Cheese During Heating and Cooling

The rheology of process cheese during heating and cooling was examined by measuring the transient and dynamic linear viscoelastic properties of regular fat, lower moisture and an 80% reduced-fat, higher moisture pasteurized process cheese from 10 to 50°C. The dynamic (stress and frequency sweep) and transient (creep and recovery) rheological properties of the reduced-fat process cheese were found to be higher than that of regular-fat process cheese, indicating that fat content changed rheological properties more than moisture content. The temperature-dependent frequency dispersions of storage and loss moduli (dynamic mechanical spectra) were fitted with a power-law model, and master curves (at a reference temperature of 30°C) and shift factors were obtained by shifting the temperature-dependent frequency dispersion of dynamic mechanical spectra. The relaxation spectra (moduli, viscosities and relaxation times) of both cheeses were obtained from the master curves using the generalized Maxwell model and nonlinear regression. The viscosity distribution of corresponding Maxwell model elements were higher for the reduced-fat cheese by a factor of 1.6–4.7 compared to the regular-fat cheese, indicating that the higher moisture content in the reduced-fat process cheese did not loosen the protein matrix or soften the cheese even though higher moisture is recommended to cheese manufacturers in order to compensate for some textural defects in reduced-fat cheeses.     

Biological activities of the bioaccessible compounds after in vitro digestion of low-fat Akawi cheese made from blends of bovine and camel milk

The objective of this study was to assess protein degradation and biological activities of the water-soluble extract (WSE) and the 10 kDa permeable and nonpermeable fractions of in vitro digesta of low-fat Akawi cheese made from blends (100:0, 85:15, or 70:30) of bovine milk and camel milk and ripened for 28 d. Biological activities, such as antioxidant activities, amylase and glucosidase inhibition, angiotensin-converting enzyme inhibition, and antiproliferative of the WSE, and the 10 kDa permeable and nonpermeable fraction of the digesta were assessed. To identify the nature of the bioaccessible compounds, untargeted metabolomic analysis was carried out by ultra-high performance liquid chromatography–quadrupole time-of-flight mass spectrometry. Higher o-phthaldialdehyde absorbances were observed in cheeses made of bovine-camel milk blends compared with cheese from bovine milk only. The WSE from these blends also exhibited higher angiotensin-converting enzyme inhibitory effects and higher antiproliferative effects than from bovine milk. The results from this study suggest that the use of blends of camel milk and bovine milk can modulate biological activities of low-fat Akawi cheese.     

拉伸温度对纤丝干酪流变学特性及微观结构的影响

用小型单螺杆拉伸机制作纤丝干酪,研究拉伸温度对纤丝干酪流变学性质和微观结构的影响。扫描电镜观察结果表明,干酪凝块经过拉伸过程后由无定型的三维结构转变为近乎平行排列的线性纤维状结构,拉伸温度越高蛋白质网络结构越致密。这一结果与通过离心法测定纤丝干酪可榨乳清含量结果一致,说明经过热烫拉伸处理后酪蛋白矩阵持水力增大,且拉伸温度越高酪蛋白矩阵持水力越大。干酪从25 ℃升温至80 ℃的动态流变学温度扫描结果表明,拉伸温度低于50 ℃时制作的纤丝干酪加热后流变学性质不稳定。干酪从0.1-10 Hz动态流变学频率扫描结果表明,纤丝干酪表现出较强的粘弹性以及剪切稀化特性,且随着拉伸温度的升高,这种特性表现的愈加明显。TPA分析结果表明,拉伸温度对纤丝干酪硬度影响最显著。     

Effect of substituting whey cream for sweet cream on the textural and rheological properties of cream cheese

In the manufacture of cream cheese, sweet cream and milk are blended to prepare the cream cheese mix, although other ingredients such as condensed skim milk and skim milk powder may also be included. Whey cream (WC) is an underutilized fat source, which has smaller fat droplets and slightly different chemical composition than sweet cream. This study investigated the rheological and textural properties of cream cheeses manufactured by substituting sweet cream with various levels of WC. Three different cream cheese mixes were prepared: control mix (CC; 0% WC), cream cheese mixes containing 25% WC (25WC; i.e., 75% sweet cream), and cream cheese mixes with 75% WC (75WC; i.e., 25% sweet cream). The CC, 25WC, and 75WC mixes were then used to manufacture cream cheeses. We also studied the effect of WC on the initial step in cream cheese manufacture (i.e., the acid gelation process monitored using dynamic small amplitude rheology). Acid gels were also prepared with added denatured whey proteins or membrane proteins/phospholipids (PL) to evaluate how these components affected gel properties. The rheological, textural, and sensory properties of cream cheeses were also measured. The WC samples had significantly higher levels of PL and insoluble protein compared with sweet cream. An increase in the level of WC reduced the rate of acid gel development, similar to the effect of whey phospholipid concentrate added to mixes. In cream cheese, an increase in the level of added WC resulted in significantly lower storage modulus values at temperatures <20°C. Texture results, obtained from instrumental and sensory analyses, showed that high level of WC resulted in significantly lower firmness or hardness values and higher stickiness compared with cream cheeses made with 25WC or CC cream cheeses. The softer, less elastic gels or cheeses resulting from the use of high levels of WC are likely due to the presence of components such as PL and proteins from the native milk fat globule membrane. The use of low levels of WC in cream cheese did not alter the texture, whereas high levels of WC could be used if manufacturers want to produce more spreadable products.     

Effects of the concentration of insoluble calcium phosphate associated with casein micelles on the functionality of directly acidified cheese

Directly acidified cheeses with different insoluble Ca (INS Ca) contents were made to test the hypothesis that the removal of INS Ca from casein micelles (CM) would directly contribute to the softening and flow behavior of cheese at high temperature. Skim milk was directly acidified with dilute lactic acid to pH values of 6.0, 5.8, 5.6, or 5.4 to remove INS Ca (pH trial). Lowering milk pH also reduced protein charge repulsion, which could influence melt. In a second treatment, EDTA (0, 2, 4, or 6 mM) was added to skim milk that was subsequently acidified to pH 6.0 (EDTA trial). Both types of milks were then made into directly acidified cheese. Cheese properties were determined at approximately 10 h after pressing to reduce possible confounding effects of proteolysis. The INS Ca content was determined by the acid-base titration method. Dynamic low-amplitude oscillatory rheology was used to measure the viscoelastic properties of cheese during heating from 5 to 80°C. The composition of all cheeses was as similar as possible, with cheese-making procedures being modified to obtain similar moisture contents (∼55%). Insoluble Ca contents of cheeses significantly decreased with a reduction in pH or with the addition of EDTA to skim milk. The pH values of cheeses in the pH trial varied, but all cheeses in the EDTA trial had similar pH values (∼5.73). In the pH trial, the reduction in cheese pH and consequent decrease in INS Ca content resulted in a reduction in the G′ values of cheeses at 20°C. In contrast, the G′ values at 20°C in cheeses from the EDTA trial increased with EDTA addition up to 4 mM EDTA. The G′ values at 70°C of cheeses from the pH trial decreased with a decrease in cheese pH, and a similar decrease was observed in the G′ values of cheese from the EDTA trial with an increase in EDTA concentration even though these cheeses had a similar pH value. In both trials, loss tangent (LT) values increased with temperatures >30°C and reached a maximum at approximately 70°C. In the pH trial, LT values at 70°C increased from 1.50 to 4.24 with a decrease in cheese pH from 5.78 to 5.21. The LT values increased from 1.43 to 3.23 with an increase in the concentration of added EDTA from 0 to 6 mM. In the EDTA trial, the decrease in G′ and increase in LT values at 70°C were due to the reduction in INS Ca content, because the pH values of these cheeses were the same. It can be concluded that the loss of INS Ca increases the melting in cheeses that have the same pH and gross chemical composition, and removal of INS Ca can even make cheese at high pH (∼5.73) exhibit reasonable melt characteristics.     

Effects of starter level, draining time and aging on the physicochemical, organoleptic and rheological properties of feta cheese

Feta cheese was made from ewe's milk using three different levels of starter (0.20, 0.50 and 0.75%) and two draining times (6 and 20 h). Cheese made with addition of 0.75% starter had a lower pH and moisture content than the cheeses made with 0.20 and 0.50% starter. With the increase in starter level there was also an increase in cheese fat content, although the fat in dry matter remained almost constant. The lower level of starter resulted in cheese with lower protein content, while other cheese components were not significantly affected by the starter levels used. The yield of cheese made with addition of 0.75% starter was significantly lower than the yield of cheeses made with the other levels. Also, the yield of cheeses made with 6 h drainage was greater than the yield of cheeses made with 20 h drainage. In general, the organoleptic and rheological properties of cheeses were not affected by the three levels of starter used for feta cheese manufacture.     

Reduced fat process cheese made from young reduced fat Cheddar cheese manufactured with exopolysaccharide-producing cultures

In a previous study, exopolysaccharide (EPS)-producing cultures improved textural and functional properties of reduced fat Cheddar cheese. Because base cheese has an impact on the characteristics of process cheese, we hypothesized that the use of EPS-producing cultures in making base reduced fat Cheddar cheese (BRFCC) would allow utilization of more young cheeses in making reduced fat process cheese. The objective of this study was to evaluate characteristics of reduced fat process cheese made from young BRFCC containing EPS as compared with those in cheese made from a 50/50 blend of young and aged EPS-negative cheeses. Reduced fat process cheeses were manufactured using young (2 d) or 1-mo-old EPS-positive or negative BRFCC. Moisture and fat of reduced fat process cheese were standardized to 49 and 21%, respectively. Enzyme modified cheese was incorporated to provide flavor of aged cheese. Exopolysaccharide-positive reduced fat process cheese was softer, less chewy and gummy, and exhibited lower viscoelastic moduli than the EPS-negative cheeses. The hardness, chewiness, and viscoelastic moduli were lower in reduced fat process cheeses made from 1-mo-old BRFCC than in the corresponding cheeses made from 2-d-old BRFCC. This could be because of more extensive proteolysis and lower pH in the former cheeses. Sensory scores for texture of EPS-positive reduced fat process cheeses were higher than those of the EPS-negative cheeses. Panelists did not detect differences in flavor between cheeses made with enzyme modified cheese and aged cheese. No correlations were found between the physical and melting properties of base cheese and process cheese.     

Impact of modifications in acid development on the insoluble calcium content and rheological properties of Cheddar cheese

Cheddar cheese was made from milk concentrated by reverse osmosis (RO) to increase the lactose content or from whole milk. Manufacturing parameters (pH at coagulant addition, whey drainage, and milling) were altered to produce cheeses with different total Ca contents and low pH values (i.e., <5.0) during ripening. The concentration of insoluble (INSOL) Ca in cheese was measured by cheese juice method, buffering by acid-base titration, rheological properties by small amplitude oscillatory rheometry, and melting properties by UW-Melt Profiler. The INSOL Ca content as a percentage of total Ca in all cheeses rapidly decreased during the first week of aging but surprisingly did not decrease below approximately 41% even in cheeses with a very low pH (e.g., ∼4.7). Insoluble Ca content in cheese was positively correlated (r = 0.79) with cheese pH in both RO and nonRO treatments, reflecting the key role of pH and acid development in altering the extent of solubilization of INSOL Ca. The INSOL Ca content in cheese was positively correlated with the maximum loss tangent value from the rheology test and the degree of flow from the UW-Melt Profiler. When cheeses with pH <5.0 where heated in the rheometer the loss tangent values remained low (<0.5), which coincided with limited meltability of Cheddar cheeses. We believe that this lack of meltability was due to the dominant effects of reduced electrostatic repulsion between casein particles at low pH values (<5.0).     

Insoluble calcium content and rheological properties of Colby cheese during ripening

Colby cheese was made using different manufacturing conditions (i.e., varying the lactose content of milk and pH values at critical steps in the cheesemaking process) to alter the extent of acid development and the insoluble and total Ca contents of cheese. Milk was concentrated by reverse osmosis (RO) to increase the lactose content. Extent of acid development was modified by using high (HPM) and low (LPM) pH values at coagulant addition, whey drainage, and curd milling. Total Ca content was determined by atomic absorption spectroscopy, and the insoluble (INSOL) Ca content of cheese was measured by the cheese juice method. The rheological and melting properties of cheese were measured by small amplitude oscillatory rheometry and UW-Melt Profiler, respectively. There was very little change in pH during ripening even in cheese made from milk with high lactose content. The initial (d 1) cheese pH was in the range of 4.9 to 5.1. The INSOL Ca content of cheese decreased during the first 4 wk of ripening. Cheeses made with the LPM had lower INSOL Ca content during ripening compared with cheese made with HPM. There was an increase in melt and maximum loss tangent values during ripening except for LPM cheeses made with RO-concentrated milk, as this cheese had pH <4.9 and exhibited limited melt. Curd washing reduced the levels of lactic acid produced during ripening and resulted in significantly higher INSOL Ca content. The use of curd washing for cheeses made from high lactose milk prevented a large pH decrease during ripening; high rennet and draining pH values also retained more buffering constituents (i.e., INSOL Ca phosphate), which helped prevent a large pH decrease.     

Manufacture of dry‐ and brine‐salted soft camel cheeses for the camel dairy industry

Two experiments were conducted in a camel cheese study to (i) compare camel cheese to bovine cheese made from bovine milk standardised to simulate camel milk, and (ii) describe the technology for manufacture of dry (SCC‐D) and brine‐salted soft camel cheese (SCC‐B). Comparable cheese yield (camel: 7.4 ± 0.15, cow: 7.3 ± 0.55 kg/100 kg of milk) and levels of dry matter loss in whey were observed. Clotting time was 234 s for both cheeses which were made using thermophillic starters. Cheese yield was 9.31 ± 0.64 kg/100 kg with 425.6 ± 38.2 g/kg cheese dry matter for SCC‐D and 8.22 ± 0.90 kg/100 kg with 469 ± 73.8 g/kg dry matter for SCC‐B.     

Effects of exopolysaccharide-producing cultures on the viscoelastic properties of reduced-fat Cheddar cheese

The objective was to study the influence of different exopolysaccharide (EPS)-producing and nonproducing lactic cultures on the viscoelastic properties of reduced-fat Cheddar cheese. Changes in the viscoelastic properties were followed over a ripening period of 6 mo. Results showed that the elastic, viscous, and complex moduli were higher in reduced-fat cheeses made with EPS-nonproducing cultures than in full-fat cheese. No differences in the viscoelastic properties were found between young reduced-fat cheese made with a ropy strain of Lactococcus lactis ssp. cremoris (JFR1) and its full-fat counterpart. Interestingly, the changes in viscoelastic moduli in both full-fat cheese and reduced-fat cheese made with JFR1 during ripening followed the same pattern. Whereas the moduli increased during the first month of ripening in those 2 cheeses, a dramatic decrease was observed in all other cheeses. Slopes of the viscoelastic moduli as a function of frequency were lower in the full-fat than in reduced-fat cheeses. The creep test showed that fresh reduced-fat cheese made with JFR1 was less rigid and more deformable than that made with EPS-nonproducing cultures. The creep and recovery properties of young reduced-fat cheese made with JFR1 and the full-fat type were similar. No differences were found in the viscoelastic properties between reduced-fat cheese made with no EPS and those made with EPS-producing adjunct cultures of Streptococcus thermophilus. After 6 mo of ripening, cheeses made with EPS-producing cultures maintained lower elastic and viscous moduli than did those made with no EPS.     

Dynamic Rheological Properties of Process Cheese: Effect of Ca and P Content,Residual Lactose,Salt-to-Moisture Ratio and Cheese Temperature

Four treatments of Cheddar cheese with two levels (high and low) of calcium (Ca) and phosphorus (P), and two levels (high and low) of residual lactose were manufactured. Each treatment was subsequently split prior to the salting step of cheese manufacturing process and salted at two levels (high and low) for a total of eight treatments. After two months of ripening, each treatment of Cheddar cheese was used to manufacture process cheese using a twin-screw Blentech process cheese cooker. NFDM, butter oil, trisodium citrate (emulsifying salt), and water were added along with Cheddar cheese for process cheese formulation. All process cheese food formulations were balanced for moisture (43.5%), fat (25%), and salt (2%), respectively. Dynamic rheological characteristics (G′ and G″) of process cheese were determined at 1.5Hz frequency and 750 Pa stress level by using a Viscoanalyzer during heating and cooling, temperature ranges from 30°C to 70°C then back to 30°C. High Ca and P content, and high S/M (HHH and HLH) cheeses had the significantly higher elastic (G′) and viscous (G″) modulus than other cheeses during heating from 30°C to 70°C, and cooling from 70°C to 30°C. No significant difference was observed among the other process cheeses during heating and cooling. Viscoelastic properties of process cheeses were also determined in terms of transition temperature (where G′?=?G″), and tan δ during heating (30°C to 70°C). Cheeses with high Ca and P, high lactose, and high S/M content had higher transition temperature than low Ca and P, low lactose, and low S/M content process cheeses. Low Ca and P and low S/M content cheeses (LLL, LHH, LHL, HLL) exhibited more viscous characteristics than high Ca and P and high S/M content process cheeses (HHL, HLH, LLH, HHH) during heating from 30°C to 70°C. Low Ca and P, low lactose, low S/M content (LLL) process cheese was observed for highest tan δ values (0.39 to 1.43), whereas high Ca and P, high lactose, high S/M content process (HHH) had the least (0.33 to 1.06) during heating. This study demonstrates that different characteristics of natural cheese used in process cheese manufacturing have significant impact on process cheese rheological and viscoelastic properties.     

Comparison of effect of vacuum-condensed and ultrafiltered milk on cheddar cheese

The objective of this study was to compare the effects of vacuum-condensed (CM) and ultrafiltered (UF) milk on some compositional and functional properties of Cheddar cheese. Five treatments were designed to have 2 levels of concentration (4.5 and 6.0% protein) from vacuum-condensed milk (CM1 and CM2) and ultrafiltered milk (UF1 and UF2) along with a 3.2% protein control. The samples were analyzed for fat, protein, ash, calcium, and salt contents at 1 wk. Moisture content, soluble protein, meltability, sodium dodecyl sulfate-PAGE, and counts of lactic acid bacteria and nonstarter lactic acid bacteria were performed on samples at 1, 18, and 30 wk. At 1 wk, the moisture content ranged from 39.2 (control) to 36.5% (UF2). Fat content ranged from 31.5 to 32.4% with no significant differences among treatments, and salt content ranged from 1.38 to 1.83% with significant differences. Calcium content was higher in UF cheeses than in CM cheeses followed by control, and it increased with protein content in cheese milk. Ultrafiltered milk produced cheese with higher protein content than CM milk. The soluble protein content of all cheeses increased during 30 wk of ripening. Condensed milk cheeses exhibited a higher level of proteolysis than UF cheeses. Sodium dodecyl sulfate-PAGE showed retarded proteolysis with increase in level of concentration. The breakdown of alphas1- casein and alphas1-I-casein fractions was highest in the control and decreased with increase in protein content of cheese milk, with UF2 being the lowest. There was no significant degradation of beta-casein. Overall increase in proteolytic products was the highest in control, and it decreased with increase in protein content of cheese milk. No significant differences in the counts of lactic starters or nonstarter lactic acid bacteria were observed. Extent as well as method of concentration influenced the melting characteristics of the cheeses. Melting was greatest in the control cheeses and least in cheese made from condensed milk and decreased with increasing level of milk protein concentration. Vacuum condensing and ultrafiltration resulted in Cheddar cheeses of distinctly different quality. Although both methods have their advantages and disadvantages, the selection of the right method would depend upon the objective of the manufacturer and intended use of the cheese.     

Effect of Ca and P Content,Residual Lactose,and Salt-to-Moisture Ratio on the Model Parameters of Process Cheese Linear Viscoelastic Properties

The main aim of this study was to investigate the influence of two different levels (high and low) of Ca and P (calcium and phosphorous) content, residual lactose, and salt-to-moisture (S/M) ratio on viscoelastic properties of eight different process cheeses. Frequency sweep was performed at 750 Pa on all experimental process cheese samples to determine the power-law model parameters. Process cheeses with high Ca and P content and high S/M ratio were significantly harder (P < 0.05) (higher storage and loss modulus, and lower creep and recovery compliance) compared to low Ca and P content and low S/M ratio process cheeses. However, no significant difference was observed (P > 0.05) for power-law parameters between high/low residual lactose content process cheese samples. Six-element Kelvin-Voigt model was used to predict the creep compliances for eight different process cheeses. This model described the affect of above treatment's retardation spectra (compliances, viscosities, and retardation times) obtained from creep tests. Both of these measurements indicated the similar trend on linear viscoelastic properties for eight different process cheeses.     

Evaluation of cheese authenticity and proteolysis by HPLC and urea–polyacrylamide gel electrophoresis

Chromatographic and electrophoretic methods have been established as useful tools in characterising cheese ripening and in the detection of milk adulteration. The purpose of this work was to evaluate casein proteolysis of cheeses made from bovine, ovine or mixtures of bovine and ovine milks, as well as ovine cheese authenticity, for 30 days of ripening by HPLC and urea–polyacrylamide gel electrophoresis.Complementary information was obtained by both techniques when applied to the study of casein proteolysis during 30 days of ripening of ovine milk cheeses, ovine milk cheeses with 10% and 20% of bovine milk and bovine milk cheeses, manufactured according to the traditional Terrincho technology. For ovine cheeses, α-casein was the fraction that showed the higher degradation during cheese ripening. A similar behaviour was observed for ovine milk cheese with 10% of bovine milk. The profile for ovine milk cheese with 20% of bovine milk was more similar to that obtained for bovine cheese. Concerning bovine milk cheeses, electrophoresis was the most sensitive technique for the evaluation of proteolysis in these cheeses.Ten and 20% of bovine milk could be detected in ovine milk cheeses by urea–polyacrylamide gel electrophoresis and HPLC, respectively, even after 30 days of ripening.     

Interaction between sodium chloride and texture in semi-hard Danish cheese as affected by brining time,dl-starter culture,chymosin type and cheese ripening

Reduced NaCl in semi-hard cheeses greatly affects textural and sensory properties. The interaction between cheese NaCl concentration and texture was affected by brining time (0–28 h), dl-starter cultures (C1, C2, and C3), chymosin type (bovine or camel), and ripening time (1–12 weeks). Cheese NaCl levels ranged from <0.15 to 1.90% (w/w). NaCl distribution changed during ripening; migration from cheese edge to core led to a more homogeneous NaCl distribution after 12 weeks. As ripening time increased, cheese firmness decreased. Cheeses with reduced NaCl were less firm and more compressible. Cheeses produced with C2 were significantly firmer than those produced with C1; cheeses produced with C3 had higher firmness and compressibility. In NaCl reduced cheese, use of camel chymosin as coagulant resulted in significantly higher firmness than that given using bovine chymosin. Overall, cheese NaCl content is reducible without significant textural impact using well-defined starter cultures and camel chymosin.