Curd pH Research Articles

Effect of seaweed flakes addition on the development of bioactivities in functional Camembert‐type cheese

SummaryThe effect of adding Palmaria palmata or Saccharina longicruris to Camembert‐type cheese on both the antioxidant capacity (ORAC) and Angiotensin I‐converting enzyme (ACE)‐inhibitory activity has been studied with the aim of developing a functional food. The nutritional composition showed that P. palmata had the highest total protein and carbohydrate contents while S. longicruris demonstrated the highest total fibre and minerals contents. The bioactivities determined in the S. longicruris soluble extract were the highest. Three cheese model curds were studied: cheese control (CC), 2% of P. palmata (C2PP) and 2% of S. longicruris (C2SL). During ripening (20 days), the curd pH of all treatments was significantly similar, as their ORAC values, starting at 0 and reaching 41.28 mmol TE g−1. The ACE‐inhibitory activity of the three treatments was significantly similar, at day 0 (13.20%) and day 20 (58.27%). The feasibility of including these two seaweeds into Camembert‐type cheeses was validated through the adequate development of bioactivities during ripening supporting promising food applications.

Some parameters to process camel milk into cheese

Cheese from camel milk was never produced by traditional way. However, Hansen© (Denmark) delivered recently new coagulant agent named ?Chy-Max M? containing transgenic camel chymosine. In the present study, impact of calcium, lactation stage and curd acidification were investigated. Camel milk was shared into 6 samples (100g each) submitted to 3 types of treatment (1. calcium chloride solution (500 g/L diluted 1/10 water); 2. powder of calcium phosphate; 3. no calcium) and 2 temperatures (20°C/36°C). Rennet 50 µL/L (ChyMax) was added in all samples. Milk coagulation was faster at 36°C and renneting pH lower. No difference in clotting time and curd firmness after calcium addition was observed. The curd firmness at 36°C was stronger than at 20°C. For measuring impact of lactation stage, coagulation capacity and curd yield on milk was tested in milk provided by one camel from 12th to 25th day postpartum. Milk was coagulated by Chy-Max (50 µL/L/20°C). No coagulation was observed in the first days of experiment. Then curd start to be formed, but with low yield. The curd was correct and ready to use for cheese making only from the 20th day post-partum. Acidification of camel cheese curd without starters was measured at 20°C and 36°C during 10 hours. Milk pH and curd pH were measured during all cheese processing. At the beginning, milk pH was 6.38 whatever the temperature. Acidification was faster at 36°C than at 20°C. At the time of coagulation, pH of 20°C curd was 5.80 vs 5.08 at 36°C.

Optimization of conditions for probiotic curd formulation by Enterococcus faecium MTCC 5695 with probiotic properties using response surface methodology.

Enterococcus faecium MTCC 5695 possessing potential probiotic properties as well as enterocin producing ability was used as starter culture. Effect of time (12-24h) and inoculum level (3-7% v/v) on cell growth, bacteriocin production, antioxidant property, titrable acidity and pH of curd was studied by response surface methodology (RSM). The optimized conditions were 26.48h and 2.17%v/v inoculum and the second order model validated. Co cultivation studies revealed that the formulated product had the ability to prevent growth of foodborne pathogens that affect keeping quality of the product during storage. The results indicated that application of E. faecium MTCC 5695 along with usage of optimized conditions attributed to the formation of highly consistent well set curd with bioactive and bioprotective properties. Formulated curd with potential probiotic attributes can be used as therapeutic agent for the treatment of foodborne diseases like Traveler's diarrhea and gastroenteritis which thereby help in improvement of bowel health.

Modelling of pH, dry matter and mineral content of curds during soft cheese drainage

The influence of the temperature at the rennet addition (31.2, 32.0 and 32.8 °C) and of the starter type on the soft cheese drainage process was studied. Off-line measurements of pH, cal- cium and phosphorous concentrations, as well as dry matter of the curd were performed in parallel with on-line measurements of the weight and pH of the whey. Only the starter type was found to have a significant influence on the curd and whey pH, on the calcium concentration in the curd and on the calcium/dry matter ratio. Correlations were established between weight of the whey and dry matter of the curd, as well as between pH of the whey and physico-chemical measurements in the curd. Linear regressions gave satisfactory results only when performed separately for each type of starter. Artificial neural networks allowed the building of common models for both starters and pre- dicting curd pH, calcium concentration and the calcium/dry matter ratio using the pH of the whey at one hour after moulding. Drainage / curd characteristics / pH / starter / on-line measurement / modelling

Effect of Rennet Coagulation Time on Composition, Yield, and Quality of Reduced-Fat Cheddar Cheese

This study compared the effect of coagulum firmness at cutting on composition of 50% reduced-fat Cheddar cheese. Coagulum firmness was determined by subjective evaluation by the cheese maker. Three firmness levels were tested, and these corresponded to average times of coagulant addition to cutting the curd of 25, 48, and 65min. A slow acid-producing culture was used, and ripening times were altered to give similar curd pH values throughout cheese making. A longer rennet coagulation time (firmer coagulum at cutting) resulted in an increase in cheese moisture as well as an increase in cheese yield. The percentages of fat recovered in the cheese decreased with increasing curd firmness. The percentage of nitrogen recovered in the cheese was similar among the treatments. The amount of whey collected from the curd after milling increased as the coagulum firmness at cutting increased. Higher moisture content and lower pH of cheese made from the firmer curd at cutting contributed to softer, smoother-bodied cheeses, but the Cheddar flavor intensity was not affected.

Effect of pH and time on the quantity of readily available water within fresh cheese curd

Some of the textural changes that occur early in cheese maturation may be related to the redistribution of water within the cheese matrix. To examine this, a model cheese curd system was devised and explored. Initially, cheese curd was prepared using starter and chymosin and the curd pH was controlled by varying the draining and salting pH values. The quantity of serum that could be centrifuged from the resultant curd was less for lower pH curd and decreased in volume with time. The curd pH decreased with time. In the protocol finally adopted, milk was acidified with lactic acid and coagulated with Rennilase 46L. After cheddaring, salting and light pressing, the samples of this curd were finely diced and mixed with glucono-δ-lactone to give curd samples with comparable moisture contents, similar casein proteolysis rates but different pH values. The quantity of serum that could be centrifuged from these samples was greater for pH 5·6 curd than for pH 5·2 curd and decreased faster for the lower pH curd. Neither the curd moisture nor the pH changed significantly during curd storage and the casein proteolysis was low. These results for the model curd system are consistent with known water absorption characteristics of casein curd under ‘equilibrium’ conditions and the effects of pH and mineral salts on this absorption. It was concluded that, during the early stages of cheese ripening, there may be a redistribution of moisture within the cheese, related to the basic properties of the protein matrix and the transient effects of curd salting, rather than as a direct consequence of glycolytic and proteolytic changes.

Effect of Packaging and Storage Conditions on Calcium Lactate Crystallization on the Surface of Cheddar Cheese

Eight vats of milled curd Cheddar cheese were manufactured in a commercial cheese plant. Four consecutive vats (controls) were made according to the routine manufacturing schedule used at the cheese plant. Curd pH at drain was 6.30 and pH of the curd at mill was 5.45. Four experimental vats were made similarly to the controls except that the cook (stir-out), and cheddaring times were changed to facilitate draining and milling at a curd pH of 6.10 and 5.30, respectively. The development of calcium lactate crystals was evaluated on 255-g pieces of cheese packaged with a gas flush and heat sealed or vacuumed and heat sealed and stored at 4.4 or 7.2°C. The experimental vats had lower total lactic acid concentrations than did the control vats but few differences were observed in the extent of calcium lactate crystal formation between control and experimental vats. Although seemingly contradictory, cheeses with no crystals also had the lowest total and D(−)-lactic acid. Crystals developed faster and to a greater extent in gas-flushed packaged cheeses stored at 4.4°C than in similarly packaged cheeses stored at 7.2°C. Very little crystal development was observed in vacuum-packaged cheeses until 5 mo after packaging, regardless of storage temperature. The package condition, i.e., integrity of the packaging material to the cheese surface, played the major role in preventing the development of calcium lactate crystals.

Effects of Lactic Cultures on Acidity and Firmness of Cottage Cheese Coagulum

Summary Nonfat dry milk reconstituted to give 11% solids-not-fat was made into Cottage Cheese coagulum at 90° F., by adding 7% starter and 1ml. rennet/1,000lb. of skimmilk. Seventeen different cultures were used. A close relation was found between pH of curd and curd strength produced by active cultures. Regardless of their activity, the cultures showed essentially the same relation between curd strength and decrease in pH after coagulation. The 17 cultures varied widely in their relations between curd strength and titratable acidity of whey, and in their relations between pH of curd and titratable acidity of whey. High titratable acidity produced by some cultures at the A–C end point was associated with floating curd during heating. The phenomenon seems to be explained by varied production by the different cultures of weakly ionized acids such as carbonic and acetic acid. The data explain why occasional vats of milk do not coagulate at normal titratable acidity values, and indicate that it is not always desirable to use the same culture for making both Cottage Cheese and Cultured Buttermilk.