Texture,flavor, and sensory quality of buffalo milk Cheddar cheese as influenced by reducing sodium salt content

The adverse health effects of dietary sodium demand the production of cheese with reduced salt content. The study was aimed to assess the effect of reducing the level of sodium chloride on the texture, flavor, and sensory qualities of Cheddar cheese. Cheddar cheese was manufactured from buffalo milk standardized at 4% fat level by adding sodium chloride at 2.5, 2.0, 1.5, 1.0, and 0.5% (wt/wt of the curd obtained). Cheese samples were ripened at 6 to 8°C for 180 d and analyzed for chemical composition after 1 wk; for texture and proteolysis after 1, 60, 120, and 180 d; and for volatile flavor compounds and sensory quality after 180 d of ripening. Decreasing the salt level significantly reduced the salt-in-moisture and pH and increased the moisture-in-nonfat-substances and water activity. Cheese hardness, toughness, and crumbliness decreased but proteolysis increased considerably on reducing the sodium content and during cheese ripening. Lowering the salt levels appreciably enhanced the concentration of volatile compounds associated with flavor but negatively affected the sensory perception. We concluded that salt level in cheese can be successfully reduced to a great extent if proteolysis and development of off-flavors resulted by the growth of starter and nonstarter bacteria can be controlled.     

Viscoelastic Property Changes in Cheddar Cheese During Ripening

The rheological properties of pasteurized and raw milk Cheddar cheese were studied using oscillatory dynamic measurements, and a specially designed rheometer fixture that prevented specimen slippage. Dynamic measurements within the linear viscoelastic range were made throughout ripening. Within-cheese changes, as related to ripening time, as well as between-cheese-type differences in G’ and G” were observed. Differences in rheological characteristics were attributed to proteolytic activities in Cheddar cheese during ripening. Specific peptide profiles associated with proteolysis during ripening may affect cheese rheological properties.     

Survival of microencapsulated Bifidobacterium longum in Cheddar cheese during production and storage

The aim of this study was to evaluate the effect of microencapsulation (ME) in alginate beads on the viability of Bifidobacterium longum 15708 in terms of their tolerance to freezing, storage in a frozen state, cheddar cheese manufacturing and storage as well as to a simulated gastro-intestinal environment. Two ME methods namely i) droplet extrusion method (ADE) and ii) emulsion method, involving two polymers (native (NA) and palmitoylated alginate (PA)) were compared. Results showed that ADE maintained higher viability of B. longum after 24 h freezing at −80 °C with no viability loss as compared to the emulsion process and free cells which lost approximately 0.8 and 1.5 log CFU/mL respectively. However, during a 4 weeks storage period at −80 °C, no significant difference (P > 0.05) was observed in the survival of free and immobilized B. longum, with no loss of viability. Cheddar cheeses supplemented with B. longum culture were prepared and analysed during storage at 4 °C. After 21 days of storage, Cheddar cheese containing encapsulated B. longum in NA and PA polymers produced with the emulsion process showed a good survival with 2 log CFU/mL reduction after 21 days, as compared to ADE-encapsulated B. longum and free cells with 3 and 4 log CFU/mL reductions respectively. The immobilized bacteria in both polymers were also more resistant than free cells to simulated gastric and intestinal environments by a factor of 30.     

The effect of sodium reduction with and without potassium chloride on the survival of Listeria monocytogenes in Cheddar cheese

Sodium chloride (NaCl) in cheese contributes to flavor and texture directly and by its effect on microbial and enzymatic activity. The salt-to-moisture ratio (S/M) is used to gauge if conditions for producing good-quality cheese have been met. Reductions in salt that deviate from the ideal S/M range could result in changing culture acidification profiles during cheese making. Lactococcus lactis ssp. lactis or Lc. lactis ssp. cremoris are both used as cultures in Cheddar cheese manufacture, but Lc. lactis ssp. lactis has a higher salt and pH tolerance than Lc. lactis ssp. cremoris. Both salt and pH are used to control growth and survival of Listeria monocytogenes and salts such as KCl are commonly used to replace the effects of NaCl in food when NaCl is reduced. The objectives of this project were to determine the effects of sodium reduction, KCl use, and the subspecies of Lc. lactis used on L. monocytogenes survival in stirred-curd Cheddar cheese. Cheese was manufactured with either Lc. lactis ssp. lactis or Lc. lactis ssp. cremoris. At the salting step, curd was divided and salted with a concentration targeted to produce a final cheese with 600 mg of sodium/100 g (control), 25% reduced sodium (450 mg of sodium/100 g; both with and without KCl), and low sodium (53% sodium reduction or 280 mg of sodium/100 g; both with and without KCl). Potassium chloride was added on a molar equivalent to the NaCl it replaced to maintain an equivalent S/M. Cheese was inoculated with a 5-strain cocktail of L. monocytogenes at different times during aging to simulate postprocessing contamination, and counts were monitored over 27 or 50 d, depending on incubation temperature (12 or 5°C, respectively). In cheese inoculated with 4 log₁₀ cfu of L. monocytogenes/g 2 wk after manufacture, viable counts declined by more than 3 log₁₀ cfu/g in all treatments over 60 d. When inoculated with 5 log₁₀ cfu/g at 3 mo of cheese age, L. monocytogenes counts in Cheddar cheese were also reduced during storage, but by less than 1.5 log₁₀ cfu/g after 50 d. However, cheese with a 50% reduction in sodium without KCl had higher counts than full-sodium cheese at the end of 50 d of incubation at 4°C when inoculated at 3 mo. When inoculated at 8 mo postmanufacture, this trend was only observed in 50% reduced sodium with KCl, for cheese manufactured with both cultures. This enhanced survival for 50% reduced-sodium cheese was not seen when a higher incubation temperature (12°C) was used when cheese was inoculated at 3 mo of age and monitored for 27 d (no difference in treatments was observed at this incubation temperature). In the event of postprocessing contamination during later stages of ripening, L. monocytogenes was capable of survival in Cheddar cheese regardless of which culture was used, whether or not sodium had been reduced by as much as 50% from standard concentrations, or if KCl had been added to maintain the effective S/M of full-sodium Cheddar cheese.     

Effect of trisodium citrate concentration and cooking time on the physicochemical properties of pasteurized process cheese

The effects of the concentration of trisodium citrate (TSC) emulsifying salt (0.25 to 2.75%) and holding time (0 to 20 min) on the textural, rheological, and microstructural properties of pasteurized process Cheddar cheese were studied using a central composite rotatable design. The loss tangent parameter (from small amplitude oscillatory rheology), extent of flow (derived from the University of Wisconsin Meltprofiler), and melt area (from the Schreiber test) all indicated that the meltability of process cheese decreased with increased concentration of TSC and that holding time led to a slight reduction in meltability. Hardness increased as the concentration of TSC increased. Fluorescence micrographs indicated that the size of fat droplets decreased with an increase in the concentration of TSC and with longer holding times. Acid-base titration curves indicated that the buffering peak at pH 4.8, which is due to residual colloidal calcium phosphate, decreased as the concentration of TSC increased. The soluble phosphate content increased as concentration of TSC increased. However, the insoluble Ca decreased with increasing concentration of TSC. The results of this study suggest that TSC chelated Ca from colloidal calcium phosphate and dispersed casein; the citrate-Ca complex remained trapped within the process cheese matrix. Increasing the concentration of TSC helped to improve fat emulsification and casein dispersion during cooking, both of which probably helped to reinforce the structure of process cheese.     

Correlation between Cheese Meltability Determined with a Computer Vision Method and with Arnott and Schreiber Tests

ABSTRACT: Meltability of different brands of Cheddar and Mozzarella cheeses was determined with a novel computer vision method as well as with 2 traditional methods, that is, the Arnott and Schreiber tests. Correlation between the results of these methods was analysed and it showed that the meltability determined with a computer vision system was significantly (P < 0.0001) interrelated with the Arnott (R²= 0.69) and Schreiber (R²= 0.88) meltabilities. The computer vision method provided an accurate quantitative account of the physical changes in cheese during melting, and thus was capable of revealing meltability differences of cheese that were difficult to distinguish by the traditional methods. The new approach was also applicable to a wide range of cheeses.     

Impact of milk preacidification with CO2 on cheddar cheese composition and yield

Preacidification of milk for cheese making may have a beneficial impact on increasing proteolysis during cheese aging. Unlike other acids, CO(2) can easily be removed from whey. The objectives of this work were to determine the effect of milk preacidification on Cheddar cheese composition, the recovery of individual milk components, and yield. Carbon dioxide was injected inline after the cooling section of the pasteurizer. Cheeses with and without added CO(2) were made simultaneously from the same batch of milk. This procedure was replicated 3 times. Carbon dioxide in the cheese milk was about 1600 ppm, which resulted in a milk pH of about 5.9 at 31 degrees C. The starter culture and coagulant addition rates were the same for both the CO(2) treatment and the control. The whey pH at draining of the CO(2) treatment was lower than the control. Total make time was shorter for the CO(2) treatment compared with the control. Cheese manufactured from milk acidified with CO(2) retained less of the total calcium and fat than the control cheese. The higher fat loss was primarily in the whey at draining. Preacidification with CO(2) did not alter the crude protein recovery in the cheese. The CO(2) treatment resulted in a higher added salt recovery in the cheese and produced a cheese that contained too much salt. Considering the higher added salt retention, the salt application rate could be lowered to achieve a typical cheese salt content. Cheese yield efficiency of the CO(2) treated milk was 4.4% lower than the control due to fat loss. Future work will focus on modifying the make procedure to achieve a normal fat loss into the whey when CO(2) is added to milk.