Proteolysis and textural properties of low‐fat ultrafiltered Feta cheese as influenced by maltodextrin

Maltodextrin was used as a fat replacer in low‐fat ultrafiltered cheese. Fat was replaced with 25% maltodextrin milk solution (w/w) in cheese at 15 and 50% (w/w). The chemical, rheological and sensory properties as well as the microstructure of the cheese samples were evaluated after storage for 2 months at 8 °C. Maltodextrin affected the chemical (pH, dry matter, fat, water‐soluble nitrogen to total nitrogen, nonprotein nitrogen to total nitrogen, total free amino acid) and rheological (mean relaxation time) properties, as well as the microstructure. In general, based on textural properties, sensory evaluation and economic aspects, the 50%‐fat‐reduced sample was selected as the best treatment.     

Role of salt in Iranian ultrafiltered Feta cheese: Some textural and physicochemical changes during ripening

The effect of NaCl (0–4%) on the ripening of Iranian ultrafiltered (UF)‐Feta cheese was assessed over 120 days of ripening at 4 °C. Whey percentage, whey salt, whey pH, cheese pH and textural properties of hardness and cohesiveness were monitored, and experimental modelling performed using response surface methodology. Texture, pH and whey percentage were significantly affected by NaCl and ripening. The maximum whey of 22% was recorded at the end of ripening period. Texture of this cheese becomes harder during ripening confirming cheese pH and whey percentage being the major determining factors. Cheese samples were more elastic than viscous with cohesiveness values of 0.6–0.9.     

Short communication: Determination of lactoferrin in Feta cheese whey with reversed-phase high-performance liquid chromatography

In the current paper, a method is introduced to determine lactoferrin in sweet whey using reversed-phase HPLC without any pretreatment of the samples or use of a separation technique. As a starting point, the most common HPLC protocols for acid whey, which included pretreatment of the whey along with a sodium dodecyl sulfate-PAGE step, were tested. By skipping the pretreatment and the separation steps while altering the gradient profile, different chromatographs were obtained that proved to be equally efficient to determine lactoferrin. For this novel 1-step reversed-phase HPLC method, repeatability was very high over a wide range of concentrations (1.88% intraday to 5.89% interday). The limit of detection was 35.46 μg/mL [signal:noise ratio (S/N) = 3], whereas the limit of quantification was 50.86 μg/mL (S/N = 10). Omitting the pretreatment step caused a degradation of the column’s lifetime (to approximately 2,000 samples). As a result, the lactoferrin elution time changed, but neither the accuracy nor the separation ability of the method was significantly influenced. We observed that this degradation could be easily avoided or detained by centrifuging the samples to remove fat or by extensive cleaning of the column after every 5 samples.     

Interaction of brine concentration, brine temperature, and presalting on salt penetration in Ragusano cheese

Thirty-one 3.6-kg blocks of Ragusano cheese were made on each of 6 different days (in different weeks) starting with a different batch of milk on each day. On d 1, 3, and 5, the cheeses were not presalted and on d 2, 4, and 6, all cheeses were presalted (PS). One of the 31 blocks of cheese was selected at random for analysis before brine salting (i.e., on d 0). The remaining 30 blocks were randomly divided into 2 groups of 15 blocks each; one group was placed in 18% brine (18%B) and the other group was placed in saturated brine (SB). For the 15 blocks within each of the 2 brine concentrations (BC), 5 blocks were placed in a brine tank at 12° C, 5 at 15° C, and 5 at 18° C, and submerged for 24 d. The research objective was to determine the combined impacts (i.e., interactions) of PS the curd before stretching, BC (SB vs. 18%B), and brine temperature (BT; 12, 15, and 18° C) on salt uptake, moisture content, and yield of Ragusano cheese. Although BC, BT, and PS each had their own separate impacts on salt uptake, there was little interaction of these effects on salt uptake when they were used in combination. The PS most quickly delivered salt to the interior of the cheese and was the most effective approach to salting for controlling early gas formation. There were strong separate impacts of BC, BT, and PS on cheese moisture content, moisture loss, and net weight loss, with BC having the largest separate impact on these parameters. Reducing BT reduced salt content and increased moisture, but the effects were small. The more important effect of reduced BT was to reduce growth of gas forming bacteria. The 18%B produced higher moisture, and less moisture and weight loss than SB. The effect of interactions of BC, BT, and PS on moisture loss and net weight loss were small. To achieve the maximum benefit from the various approaches to salting for controlling early gas formation in Ragusano cheese, PS combined with slightly lower BT (i.e., 15° C instead of 18° C) should be used. Although using 18%B instead of SB did increase salt uptake, the point at which improved salt uptake occurred due to use of 18%B did not provide benefit in prevention of early gas formation, as reported separately. However, use of 18%B instead of SB provided a 9.98% increase in cheese yield due to reduced moisture loss during brining; this would be very attractive to cheese makers. The increase in yield needs to be balanced against the risk of growth of undesirable bacteria in the 18%B and the creation of another cheese quality defect.     

Influence of presalting and brine concentration on salt uptake by Ragusano cheese

The impact of presalting and nonsaturated brine on salt uptake by Ragusano cheese was determined. The study included four treatments: 1) the traditional method using no presalting and saturated brine, 2) presalting and saturated brine, 3) no presalting and 18% brine for 8 d followed by 16 d in saturated brine, and 4) presalting and 18% brine for 8 d followed by 16 d in saturated brine. Cheese blocks were weighed and sampled before brine salting (time 0) and after 1, 4, 8, 16, and 24 d of brining for each treatment. Presalting delivered 60% of the normal level of salt in the center of the block prior to brine salting without decreasing the rate of uptake of salt from either saturated or 18% brine. Use of 18% salt brine for the first 8 d of 24 d of brine salting increased the rate of salt uptake, compared with 24 d in saturated brine. The increased rate of salt uptake with 18% brine compared with saturated brine was related to the impact of salt brine on the moisture content and porosity of the cheese near the surface of the block. Brine with higher salt content causes a rapid loss of moisture from cheese near the surface of the block. Moisture loss causes shrinkage of the cheese structure and decreases porosity, which impedes moisture movement out and salt movement into the block. The use of 18% salt brine for the first 8 d delayed the moisture loss and cheese shrinkage at the exterior of the block and allowed more salt penetration.     

Effect of soy protein supplementation on the quality of ripening Cheddar-type cheese

The impact of soy protein isolate on the proteolysis and organoleptic properties of Cheddar-type cheese during ripening was studied. Cheese was prepared from cow's milk (control) and cow's milk plus soy protein isolate by using a starter culture of Streptococcus thermophilus and Lactobacillus delbrueckii subsp . bulgaricus, and then ripened at 12  ±  1°C for 3 and 5 months. The molecular weight range and peptide fraction in the cheeses were determined by high-performance liquid chromatography (HPLC), and the microstructure was observed by scanning electron microscopy (SEM). Sensory evaluation was used to compare the flavour, body, texture and appearance of the cheeses. The results show that the molecular weight range (9924–9966  Da) in the control cheese was larger than that (6954–6957   Da) in the soy protein-treated cheese and the microstructure in the latter was less compact than in the control cheese. In the sensory evaluation, higher scores were given for some experimental cheese than the control cheese. After 5 months of ripening, the organoleptic properties of the cheese had markedly improved and no bitter off-flavour was detected in the treated cheeses. It was concluded that soy protein could be used to improve the quality of cheese and the addition of 5% soy protein isolate could be recommended for improving the flavour and texture of Cheddar-type soy supplemented cheese.     

Influence of the temperature of salt brine on salt uptake by Ragusano cheese

The influence of temperature (12, 15, 18, 21, and 24 degrees C) of saturated brine on salt uptake by 3.8-kg experimental blocks of Ragusano cheese during 24 d of brining was determined. Twenty-six 3.8-kg blocks were made on each of three different days. All blocks were labeled and weighed prior to brining. One block was sampled and analyzed prior to brine salting. Five blocks were placed into each of five different brine tanks at different temperatures. One block was removed from each brine tank after 1, 4, 8, 16, and 24 d of brining, weighed, sampled, and analyzed for salt and moisture content. The weight loss by blocks of cheese after 24 d of brining was higher, with increasing brine temperature, and represented the net effect of moisture loss and salt uptake. The total salt uptake and moisture loss increased with increasing brine temperature. Salt penetrates into cheese through the moisture phase within the pore structure of the cheese. Porosity of the cheese structure and viscosity of the water phase within the pores influenced the rate and extent of salt penetration during 24 d of brining. In a previous study, it was determined that salt uptake at 18 degrees C was faster in 18% brine than in saturated brine due to higher moisture and porosity of the exterior portion of the cheese. In the present study, moisture loss occurred from all cheeses at all temperatures and most of the loss was from the exterior portion of the block during the first 4 d of brining. This loss in moisture would be expected to decrease porosity of the exterior portion and act as a barrier to salt penetration. The moisture loss increased with increasing brine temperature. If this decrease in porosity was the only factor influencing salt uptake, then it would be expected that the cheeses at higher brine temperature would have had lower salt content. However, the opposite was true. Brine temperature must have also impacted the viscosity of the aqueous phase of the cheese. Cheese in lower temperature brine would be expected to have higher viscosity of the aqueous phase and slower salt uptake, even though the cheese at lower brine temperature should have had a more porous structure (favoring faster uptake) than cheese at higher brine temperature. Therefore, changing brine concentration has a greater impact on cheese porosity, while changing brine temperature has a larger impact on viscosity of the aqueous phase of the cheese within the pores in the cheese.     

Effects of Penicillium roqueforti and whey cheese on gross composition,microbiology and proteolysis of mould‐ripened Civil cheese during ripening

Four different types of mould‐ripened Civil cheese were manufactured. A defined (nontoxigenic) strain of a Penicillium roqueforti (SC 509) was used as the secondary starter with and without addition of the whey cheese (Lor); in parallel, secondary starter‐free counterparts were manufactured. Chemical composition, microbiology and proteolysis were studied during the ripening. The incorporation of whey cheese in the manufacture of mould‐ripened Civil cheese altered the gross composition and adversely affected proteolysis in the cheeses. The inoculated P. roqueforti moulds appeared to grow slowly on those cheeses, and little proteolysis was evident in all cheese treatments during the first 90 days of ripening. However, sharp increases in the soluble nitrogen fractions were observed in all cheeses after 90 days. Microbiological analysis showed that the microbial counts in the cheeses were at high levels at the beginning of ripening, while their counts decreased approximately 1–2 log cfu/g towards the end of ripening.     

Effect of a commercial adjunct culture on organic acid contents of low-fat Feta-type cheese

The effect of a commercial adjunct culture (CR-213, containing Lactococcus lactis subsp. cremoris and Lactococcus lactis susp. lactis and added at the level of 0.6 g kg⁻¹ or 0.9 g kg⁻¹ cheese milk) on the organic acid (OA) content of low-fat Feta-type cheese was studied. Full-fat (∼220 g kg⁻¹) and a low-fat (∼70 g kg⁻¹) cheeses were used as controls. The main OA of all cheeses throughout ripening were lactic, citric and acetic acids. The effect of ripening time was significant (P < 0.05) for all OA but treatments did not affect acetic, succinic and uric acids. Cheeses with lower fat content were found to contain significantly (P < 0.05) more lactic and citric but less butyric acid than the full-fat control. The addition of the adjunct culture had a positive effect on butyric acid, propionic acid and acetoin content. The use of the adjunct culture could enhance the production of OA in low-fat Feta-type cheeses with eventual positive effect on their sensory properties.     

Influences of rennet and container types on proteolysis of traditional Kurdish cheese during the ripening

The effect of rennet and container types was evaluated on proteolysis of traditional Kurdish cheese during 60 days ripening. The enzymes involved were commercial chymosin and traditional rennet from lamb abomasum. Goat skin (traditional container) and plastic containers were used as storage containers. The trend of proteolysis was determined by measuring the content of nitrogen (N) in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid along with the urea–polyacrylamide gel electrophoresis method. The results showed that the nitrogen in compounds soluble in water, 12% trichloroacetic acid and 5% phosphotungstic acid was higher in ripened cheeses into plastic containers; however, the containers had no significant effect on the breakdown of α‐ and β‐caseins (P < 0.05). Using commercial rennet caused the breakdown of α‐ and β‐caseins and the level of nitrogen in compounds soluble in water to increase. Finally, however, the amount of α‐ and β‐caseins breakdown was trivial, and α‐casein was decreased more than β‐casein in all samples.     

Effects of different ripening procedures on the final characteristics of Picante cheese

 Picante da Beira Baixa (or Picante) cheese is a hard, piquant, salted traditional cheese manufactured in Portugal from raw sheep's and goat's milks. The purpose of this work was to quantitatively assess the influence of various ripening procedures on the final characteristics of Picante cheese. Two alternative ripening protocols were considered, the traditional one and another with controlled environmental conditions via use of maturation chambers set at different preselected temperatures. The experimental cheeses were characterised in terms of microbiological, physicochemical, biochemical, sensorial and textural properties. Ripening time and temperature were statistically significant parameters for all microflora. The two ripening methods led to statistically significant differences in all physicochemical and biochemical parameters, especially the moisture content and the soluble nitrogen fractions (i.e. water loss was slower and proteolysis was faster in cheeses ripened via the traditional method). Differences in microbiological, physicochemical and biochemical properties were probables implicated in differences in textural and sensorial properties, especially cheese hardness and flavour. It was concluded that the standard ripening method was closest to the traditional one in terms of final cheese characteristics when the ripening temperature was above 11.5  °C. Received: 3 February 1998     

Effects of different ripening procedures on the final characteristics of Picante cheese

 Picante da Beira Baixa (or Picante) cheese is a hard, piquant, salted traditional cheese manufactured in Portugal from raw sheep's and goat's milks. The purpose of this work was to quantitatively assess the influence of various ripening procedures on the final characteristics of Picante cheese. Two alternative ripening protocols were considered, the traditional one and another with controlled environmental conditions via use of maturation chambers set at different preselected temperatures. The experimental cheeses were characterised in terms of microbiological, physicochemical, biochemical, sensorial and textural properties. Ripening time and temperature were statistically significant parameters for all microflora. The two ripening methods led to statistically significant differences in all physicochemical and biochemical parameters, especially the moisture content and the soluble nitrogen fractions (i.e. water loss was slower and proteolysis was faster in cheeses ripened via the traditional method). Differences in microbiological, physicochemical and biochemical properties were probables implicated in differences in textural and sensorial properties, especially cheese hardness and flavour. It was concluded that the standard ripening method was closest to the traditional one in terms of final cheese characteristics when the ripening temperature was above 11.5  °C. Received: 3 February 1998     

Effect of proteolysis and calcium equilibrium on functional properties of natural cheddar cheese during ripening and the resultant processed cheese

The changes in proteolysis, calcium (Ca) equilibrium, and functional properties of natural Cheddar cheeses during ripening and the resultant processed cheeses were investigated. For natural Cheddar cheeses, the majority of the changes in pH 4.6 soluble nitrogen as a percentage of total nitrogen (pH 4.6 SN/TN) and the soluble Ca content occurred in the first 90 d of ripening, and subsequently, the changes were slight. During ripening, functional properties of natural Cheddar cheeses changed, that is, hardness decreased, meltability was improved, storage modulus at 70 °C (G'T=70) decreased, and the maximum tan delta (TDmax) increased. Both pH 4.6 SN/TN and the soluble Ca were correlated with changes in functional properties of natural Cheddar cheeses during ripening. Kendall's partial correlation analysis indicated that pH 4.6 SN/TN was more significantly correlated with changes in hardness and TDmax. For processed cheeses manufactured from natural Cheddar cheeses with different ripening times, the soluble Ca content did not show significant difference, and the trends of changes in hardness, meltability, G'T=70, and TDmax were similar to those of natural Cheddar cheeses. Kendall's partial correlation analysis suggested that only pH 4.6 SN/TN was significantly correlated with the changes in functional properties of processed cheeses.     

Effects of Mentha longifolia L. essential oil on viability and cellular ultrastructure of Lactobacillus casei during ripening of probiotic Feta cheese

The effects of Mentha longifolia L. essential oil during ripening and storage probiotic Feta cheese were studied, in relation to viability and cellular ultrastructure of Lactobacillus casei. The addition of the essential oil in the concentrations from 0.0 to 0.03% was trialled: the 0.03% treatment resulted in the highest viability of L. casei and the lowest pH value compared with other treatments (P < 0.05). Electron microscopy showed that essential oil caused no harm to L. casei. This study demonstrated the favourable effects of M. longifolia on optimal maintenance of L. casei at the end of cheese storage period.     

Effect of different curd-washing methods on the insoluble Ca content and rheological properties of Colby cheese during ripening

A curd-washing step is used in the manufacture of Colby cheese to decrease the residual lactose content and, thereby, decrease the potential formation of excessive levels of lactic acid. The objective of this study was to investigate the effect of different washing methods on the Ca equilibrium and rheological properties of Colby cheese. Four different methods of curd-washing were performed. One method was batch washing (BW), where cold water (10°C) was added to the vat, with and without stirring, where curds were in contact with cold water for 5 min. The other method used was continuous washing (CW), with or without stirring, where curds were rinsed with continuously running cold water for approximately 7 min and water was allowed to drain immediately. Both methods used a similar volume of water. The manufacturing pH values were similar in all 4 treatments. The insoluble (INSOL) Ca content of cheese was measured by juice and acid-base titration methods and the rheological properties were measured by small amplitude oscillatory rheology. The levels of lactose in cheese at 1 d were significantly higher in CW cheese (0.06-0.11%) than in BW cheeses (∼0.02%). The levels of lactic acid at 2 and 12 wk were significantly higher in CW cheese than in BW cheeses. No differences in the total Ca content of cheeses were found. Cheese pH increased during ripening from approximately 5.1 to approximately 5.4. A decrease in INSOL Ca content of all cheeses during ripening occurred, although a steady increase in pH took place. The initial INSOL Ca content as a percent of total Ca in cheese ranged from 75 to 78% in all cheeses. The INSOL Ca content of cheese was significantly affected by washing method. Stirring during manufacturing did not have a significant effect on the INSOL Ca content of cheese during ripening. Batch-washed cheeses had significantly higher INSOL Ca contents than did CW cheeses during the first 4 wk of ripening. The maximum loss tangent values (meltability index) of CW cheese at 1 d and 1 wk were significantly higher compared with those of BW cheeses. In conclusion, different curd washing methods have a significant effect on the levels of lactose, lactic acid, meltability, and INSOL Ca content of Colby cheese during ripening.     

Study of organic acids, volatile fraction and caseins of a new Halloumi-type cheese during ripening in whey brine

Organic acids, fat hydrolysis, volatile compounds and sensory characteristics of a new brine cheese which combines characteristics of Halloumi and Feta cheeses during its ripening in whey brine (100g NaCl L⁻¹) were studied. Thermotolerant protease of Mucor miehei as a coagulant enzyme and a mixture of thermotolerant starter cultures Enterococcus faecium 0165 (0.5% w/w) and Lactobacillus casei 80 10D were used. Good quality new Halloumi-type cheese was produced with higher proteolysis than traditional Halloumi cheese kept in whey brine. The volatile compounds identified comprised alcohols, aldehydes, ketones, acids, esters, hydrocarbons and sulphur compounds. Ethanol was the dominant volatile compound determined. Lactic acid was the dominant acid produced; its concentration increased during ripening, reaching a maximum value of 9929 mg kg⁻¹ at day 30. Acetic acid was also found in high amounts, which increased during cheese ripening. Lipolysis of cheese was not intense. The most abundant acids of the mature cheese were palmitic, oleic and acetic acid. The Halloumi-type cheese scored higher in the sensory analysis when fresh than did the mature cheese.     

Compositional,biochemical and textural changes during ripening of Tulum cheese made with different coagulants

In the present study, biochemical, chemical and texture changes in Tulum cheeses made using calf rennet and microbial rennets (Aspergillus niger protease and Rhizomucor miehei protease) were compared during ripening for up to 90 days. A total of 15 free fatty acids (FFAs) were detected in the cheese samples. The peroxide values (PV) of the cheeses increased significantly (P < 0.05) during ripening and the cheese made with calf rennet had the highest PV. Proteolysis in the cheeses increased as the ripening time increased. α_s1‐casein and β‐casein degradation was higher in cheeses manufactured with R. miehei protease. Cheeses made with calf rennet were significantly (P < 0.05) harder, more adhesive, more cohesive and more resilient than those made with microbial rennet.     

Electrophoretic ripening index for the evaluation of proteolysis and the deduction of the age of Parmesan cheese

We have established an electrophoretic method to evaluate proteolysis in Parmesan cheese by means of an objective ripening index. The separation of caseins by alkaline polyacrylamide gel electrophoresis (PAGE) (12% T, 2.6% C, pH 8.9, 5 M urea) is followed by the densitometric analysis of the- and-casein fractions. The relationship between the resulting coefficients (-Cn/-Cn) and the age of reference samples of Original Italian Grana Padano (6–22 months) was linear up to 15 months, allowing an evaluation of the extent of proteolysis and therefore a deduction of the age of the Parmesan samples analysed. Based on this calibration we propose to use a threshold level of 1.3 (-Cn/-Cn) to verify the required age, i.e. 12 months, of Parmesan cheese, retailed as a loaf or prepacked slices. Commercially grated Parmesan samples may contain 20% cheese rind, which has a very low degree of casein breakdown. So a threshold level of 0.8 (-Cn/-Cn) is proposed for all grated Parmesan products. The preparation of reference solutions with defined coefficients (-Cn/-Cn), corresponding to the proteolysis indices of reference samples of different aged Grana Padano is described. The coefficients (-Cn/-Cn) as well as the-casein content of two additional series of reference samples and of 49 commercial Parmesan samples taken from retail outlets in Austria and Italy are presented.     

Biochemical changes during the ripening of homemade 'San Simón da Costa' raw milk cheese

'San Simón da Costa' cheese is a traditional smoked variety produced in the northwest of Spain from cow's milk. Biochemical changes were determined during its ripening. Its high calcium and phosphorus content and its low NaCl and sodium content stand out. This cheese undergoes moderate proteolysis. The most abundant free amino acid at the end of the ripening was glutamic acid, followed by tryptophan, leucine, arginine and phenylalanine. The lipolysis throughout ripening is slight; the most abundant free fatty acid being oleic, followed by palmitic and butyric acid.