Low-sodium Cheddar cheese: Effect of fortification of cheese milk with ultrafiltration retentate and high-hydrostatic pressure treatment of cheese

Low-sodium cheeses often exhibit an acidic flavor due to excessive acid production during the manufacturing and the initial stage of ripening, which is caused by ongoing starter culture activity facilitated by the low salt-in-moisture levels. We proposed that this excessive starter-induced acidity could be prevented by the fortification of cheese milk with ultrafiltration (UF) retentates (to increase curd buffering), and by decreasing microbial activity using the application of high-hydrostatic pressure (HHP) treatment (that is, to reduce residual starter numbers). Camel chymosin was also used as a coagulant to help reduce bitterness development (a common defect in low-sodium cheeses). Three types of low-Na (0.8% NaCl) Cheddar cheeses were manufactured: non-UF fortified, no HHP applied (L-Na); UF-fortified (cheese milk total solids = 17.2 +/- 0.6%), no HHP applied (L-Na-UF); and UF-fortified, HHP-treated (L-Na-UF-HHP; 500 MPa for 3 min applied at 1 d post-cheese manufacture). Regular salt (2% NaCl) non-UF fortified, non-HHP treated (R-Na) cheese was also manufactured for comparison purposes. Analysis was performed at 4 d, 2 wk, and 1, 3, and 6 mo after cheese manufacture. Cheese functionality during ripening was assessed using texture profile analysis and dynamic low-amplitude oscillatory rheology. Sensory Spectrum and quantitative descriptive analysis was conducted with 9 trained panelists to evaluate texture and flavor attributes using a 15-point scale. At 4 d and 2 wk of ripening, L-Na-UF-HHP cheese had 2 and similar to 4.5 log lower starter culture numbers, respectively, than all other cheeses. Retentate fortification of cheese milk and HHP treatment resulted in low-Na cheeses having similar insoluble calcium concentrations and pH values compared with R-Na cheese during ripening. The L-Na-UF cheese exhibited significantly higher hardness values (measured by texture profile analysis) compared with L-Na cheese until 1 mo of ripening; however, after 1 mo, all low-Na cheeses exhibited similar hardness values, which were significantly lower than R-Na cheese. Pressure treatment significantly increased maximum loss tangent (meltability) from rheology testing and decreased melt temperature. Sensory results indicated only very slight bitterness (<2.5 out of 15-point scale) was detected in all cheeses during the 6 mo of ripening. The L-Na-UF-HHP cheese did not significantly differ in bitterness and acidity from R-Na cheese during ripening. Pressures treatment of cheese at 500 MPa and cheese milk retentate fortification could be used to improve the quality of low-Na cheese

Investigating the properties of high-pressure-treated, reduced-sodium, low-moisture, part-skim Mozzarella cheese during refrigerated storage

We proposed that the performance and sensory properties of reduced-Na, low-moisture, part-skim (LMPS) Mozzarella cheese could be extended by the application of high hydrostatic pressure (HHP) to cheese post-manufacture and thereby decrease microbial and enzymatic activity. Fermentation-produced camel chymosin was also used as a coagulant to help reduce proteolysis during storage. Average composition of the LMPS Mozzarella cheeses was 48.6 +/- 0.6% moisture, 22.5 +/- 0.4% fat, 24.5 +/- 0.6% protein, and 1.0 +/- 0.1% NaCl. Blocks of cheeses were divided into 3 groups randomly after manufacture and stored at approximately 4 degrees C for 20 wk. The control group was not HHP treated. Two weeks after manufacture, 2 groups of cheese samples were treated with HHP at 500 or 600 MPa for 3 min and then returned to storage at approximately 4 degrees C. Analysis was performed during 20 wk of storage after cheese manufacture. Texture profile analysis (TPA) and dynamic low-amplitude oscillatory rheology were used to monitor cheese functionality. Quantitative descriptive analysis was conducted with 9 trained panelists using a 15-point scale to evaluate texture and flavor attributes of unmelted cheese as well as cheeses melted on pizzas. Pressure treatments at 500 and 600 MPa resulted in approximately 1 and 2 log reduction in the numbers of starter culture, respectively, compared with the control when measured 1 d after HHP treatment. Starter numbers continued to decrease in all cheeses over the 20 wk of storage, but the decrease was larger in the HHP-treated cheeses. Even though the initial numbers of nonstarter lactic acid bacteria were the same in all cheeses, the numbers of these bacteria increased faster in the control cheeses. High-pressure treatment of LMPS Mozzarella cheese resulted in an initial (1 d after HHP treatment) increase in pH, but by 2 wk after HHP treatment there was no statistical difference in pH values between control and HHP-treated samples. Immediately after treatment, HHP-treated cheeses exhibited significantly lower TPA and sensory (unmelted) hardness. However, by 14 wk after pressure treatment, the 600-MPa HHP-treated cheese had significantly higher TPA compared with control or 500-MPa HHP-treated cheeses. Sensory panels also indicated that by 14 wk after HHP treatment, the 600-MPa treated samples were significantly firmer than the control or 500-MPa treated cheeses. Compared with control cheese, cheeses treated at 600 or 500 MPa exhibited lower water-soluble nitrogen values at 6 and 10 wk after pressure treatment, respectively. By 10 wk after pressure treatment, the levels of intact aS1-casein were significantly higher in all HHP-treated cheeses compared with the control. Pizza sensory panels indicated that 600-MPa treated cheese was significantly chewier and exhibited lower blister quantity and higher strand thickness compared with control cheeses. High hydrostatic pressure treatment of low-Na, LMPS Mozzarella cheese could result in the extension of its desired baking characteristics when the cheese is stored at refrigerated temperature

Effect of various high-pressure treatments on the properties of reduced-fat Cheddar cheese

A major problem with reduced-fat cheese is the difficulty in attaining the characteristic flavor and texture of typical full-fat versions. Some previous studies have suggested that high hydrostatic pressure (HHP) can accelerate the ripening of full-fat cheeses. Our objective was to investigate the effect of HHP on reduced-fat (similar to 7.3% fat) Cheddar cheese, with the goal of improving its flavor and texture. We used a central composite rotatable design with response surface methodology to study the effect of pressure and holding time on the rheological, physical, chemical, and microbial characteristics of reduced-fat Cheddar cheese. A 2-level factorial experimental design was chosen to study the effects of the independent variables (pressure and holding time). Pressures were varied from around 50 to 400 MPa and holding times ranged from 2.5 to 19.5 min. High pressure was applied 1 wk after cheese manufacture, and analyses were performed at 2 wk, and 1, 3, and 6 mo. The insoluble calcium content as a percentage of total Ca in cheeses were not affected by pressure treatment. Pressure applications >= 225 MPa resulted in softer cheese texture during ripening. Pressures >= 225 MPa increased melt, and resulted in higher maximum loss tangent values at 2 wk. Pressure treatment had a greater effect on cheese microbial and textural properties than holding time. High-pressure-treated cheeses also had higher pH values than the control. We did not observe any significant difference in rates of proteolysis between treatments. In conclusion, holding times of around 5 mm and pressures of >= 225 MPa could potentially be used to improve the excessively firm texture of reduced-fat cheese