Cottage cheese whey as an ingredient of cottage cheese dressing mixes

The objective of this study was to formulate and develop a good quality cottage cheese dressing using acid whey as the main ingredient. Up to 72% of cottage cheese whey was used in the dressing mixes. The percentage of fat (4.10–5.05%) and total solids (19.41–20.24%) approached the desired level and was within the legal limits for regular cottage cheese. Sensory evaluation scores for flavour, body/texture and appearance were not adversely affected by the use of acid whey. The sensory evaluation scores for all four products made with whey- or skimmed milk-based dressings were higher than the commercial control.     

Microbiological quality of ayib, a traditional Ethiopian cottage cheese

One-hundred samples of ayib, a traditional Ethiopian cottage cheese, were purchased from Awassa market and analysed for their aerobic mesophilic counts, psychrotropic counts, yeasts and molds, coliforms, spore-formers, enterococci, lactic acid bacteria, Listeria monocytogenes, staphylococci and Bacillus cereus. The majority of the samples showed counts of mesophilic aerobic bacteria, yeasts and enterococci of 10⁸, 10⁷ and 10⁷ cfu/g. About 55% of the samples were positive for coliforms and faecal coliforms. Listeria spp. were not detected in any of the samples. B. cereus and S. aureus were isolated at varying frequencies but at low numbers (10²–10³). The pH value of the samples varied between 3.3 and 4.6 with about 40% having pH lower than 3.7.     

Feta cheese texture: the effect of caprine and ovine milk concentration

Feta cheese was produced commercially with different caprine to ovine milk ratios. Milk fat concentrations, moisture and salt contents were similar for all the batches. However, the hardness and adhesive characteristics of the cheeses differed in relation to the milk ratio. The hardness of the cheese appeared to be correlated to increased goat milk content. Cryo-scanning electron microscopy (cryo-SEM) of the cheese samples showed that feta cheese with a higher proportion of caprine milk had a more compact and less porous appearance than feta produced from purely ovine milk. This difference in cheese structure helps to explain the difference in hardness between the samples.     

Fresh cheese from camel milk coagulated with Camifloc

Camel milk was processed into cheese using Camifloc and calcium chloride. Two types of cheeses were produced from camel milk, using Camifloc (CF cheese) and CaC_l2 in addition to Camifloc (CFCC cheese). The study revealed the usefulness of Camifloc in coagulation of camel milk. The time of coagulation was found to be about 2–3 h, and the yield of CFCC cheese was found to be higher than the CF cheese, while a shelf life of 4 days was obtained for both cheeses. Both cheeses showed nonsignificant variations in compositional content except for the percentages of protein and ash, which showed significant differences at P < 0.001 and P < 0.05. Sensory evaluation by taste panellists was conducted to determine the acceptability of cheeses during the storage periods. Differences were found between the CF cheese and the CFCC cheese in saltiness and overall acceptability, and higher mean scores were recorded for the CF cheese than the CFCC cheese. The study recommends the use of Camifloc in making cheese from camel milk; and if CaCl₂ is added, it can improve the cheese yield. However, we suggest that the rate of salting should be reduced, and further drying and storage of the cheese should be done.     

Evaluation of iron‐fortified Feta cheese for physicochemical and sensory properties

Standardised cow's milk (fat 3 g/100 g) was used to manufacture Feta cheese fortified with 40, 60 and 80 mg of iron/kg cheese using ferrous sulphate (FeSO₄), ferric chloride (FeCl₃), ferric pyrophosphate (Fe₄ (P₂O₇)₃) and microencapsulated ferrous sulphate. Chemical composition and sensory characteristics of fortified cheeses were determined after 60 days of ripening, during which the iron content and thiobarbituric acid (TBA) values were measured. The metallic taste, colour, flavour, overall score and TBA values were statistically (P < 0.05) affected by the source and concentration of iron. The best quality was found in cheeses fortified with 40 mg/kg of microencapsulated ferrous sulphate.     

Investigation on the microstructural and textural properties of Lighvan cheese produced from bovine milk fortified with protein and gum tragacanth during ripening

The effect of 0.02% gum tragacanth, sodium caseinate or milk protein concentrate (MPC70) on the physiochemical, microstructural and textural properties of Lighvan cheese produced from bovine milk was investigated. The microstructure of cheese samples was studied by scanning electron microscopy (SEM), and the SEM micrographs were analysed using 3D images, surface plots and binarised SEM images. The texture parameters of bovine Lighvan cheese containing sodium caseinate were similar to those of ovine Lighvan cheese, and the microstructure of the MPC‐containing bovine Lighvan cheese was closest to that of ovine Lighvan cheese.     

The effect of ovine and bovine milk on the textural properties of Lighvan cheese during ripening

The effect of milk origin on the physicochemical characteristics, microstructure and texture of Lighvan cheese was investigated over a 90‐day ripening period. Besides fat, other physicochemical properties of Lighvan cheese were affected by milk type. The moisture content of Lighvan cheese decreased when half or all the ovine milk was substituted with bovine milk. The Lighvan cheese's microstructural properties and porosity were affected by type of milk and ripening time. Compaction of cheeses manufactured from ovine and mixed ovine and bovine milk is similar, and more than that of bovine Lighvan cheese. Ovine Lighvan cheese is harder and less brittle than bovine and mixed bovine and ovine.     

The case for milk protein standardisation using membrane filtration for improving cheese consistency and quality

Milk composition varies with season owing to stage of lactation and variation in diet and weather. Variation in the concentration of milk protein is conducive to inconsistency in cheese yield, composition and quality especially where standard operating procedures are not objectively standardised with reference to casein content. Milk protein standardisation (e.g. to 4.5%) by low‐concentration factor ultrafiltration (LCFUF) or microfiltration (LCFMF) provides an effective means of obtaining more consistent cheese manufacture. Consequently, LCFUF is now widely practised. The benefits of LCFUF and LCFMF and the effect of key processing parameters on the quality of cheese from protein‐standardised milk are reviewed.     

Pre-treatment methods of Edam cheese milk. Effect on cheese yield and quality

The effect of high-temperature heat treatment (HH), microfiltration (MF) and ultrafiltration (UF) on the Edam vat milk composition, processing and cheese yield, ripening and functional characteristics were studied. The protein level of the MF and UF cheese milk was adjusted to 42 g/kg, whereas the level in the reference (REF) and HH milk was 34 g/kg. The cheese yield from ultrafiltration and microfiltration milk (CY_v) was 12.8 g/100 g milk, yield from reference and high-temperature heat treatment milk was 10.1 and 10.2 g/100 g milk, respectively. The adjusted cheese yield (ACY_r), calculated from raw milk, was lowest when MF was used. The pre-concentration method had little effect on the starter activity: no differences were observed in the pH of cheeses. The compositions of the ripened cheeses were comparable. The casein to fat ratio of MF cheese was elevated, possibly due to elevated casein to fat ratio of vat milk. Even though the high-temperature heat treatment, ultrafiltration and microfiltration cheeses were harder than reference cheese, they retained their elasticity. Resilience was significantly higher with microfiltration and ultrafiltration cheeses. The sensory quality of all cheeses was considered according to specification. The pre-treatment methods had little effect on the processing characteristics, cheese quality or yield when calculated on the basis of the quantity of original milk.     

Composition, yield, and functionality of reduced-fat Oaxaca cheese: effects of using skim milk or a dry milk protein concentrate

The effect of adding either skim milk or a commercial dry milk protein concentrate (MPC) to whole milk on the composition, yield, and functional properties of Mexican Oaxaca cheese were investigated. Five batches of Oaxaca cheeses were produced. One batch (the control) was produced from whole milk containing 3.5% fat and 9% nonfat solids (SNF). Two batches were produced from milk standardized with skim milk to 2.7 and 1.8% fat, maintaining the SNF content at 9%. In the other 2 batches, an MPC (40% protein content) was used to standardize the milk to a SNF content of 10 and 11%, maintaining the milk fat content at 3.5%. The use of either skim milk or MPC caused a significant decrease in the fat percentage in cheese. The use of skim milk or MPC showed a nonsignificant tendency to lower total solids and fat recoveries in cheese. Actual, dry matter, and moisture-adjusted cheese yields significantly decreased with skim milk addition, but increased with MPC addition. However, normalized yields adjusted to milk fat and protein reference levels did not show significant differences between treatments. Considering skim milk-added and control cheeses, actual yield increased with cheese milk fat content at a rate of 1.34 kg/kg of fat (R = 0.88). In addition, cheese milk fat and SNF:fat ratio proved to be strong individual predictors of cheese moisture-adjusted yield (r² ≈ 0.90). Taking into account the results obtained from control and MPC-added cheeses, a 2.0-kg cheese yield increase rate per kg of milk MPC protein was observed (R = 0.89), with TS and SNF being the strongest predictors for moisture adjusted yield (r² ≈ 0.77). Reduced-fat Oaxaca cheese functionality differed from that of controls. In unmelted reduced-fat cheeses, hardness and springiness increased. In melted reduced-fat cheeses, meltability and free oil increased, but stretchability decreased. These changes were related to differences in cheese composition, mainly fat in dry matter and calcium in SNF.     

Identification of micrococcaceae isolated from goat''s milk and cheese in the Poitou-Charentes region

One hundred and ninety strains of coagulase-negative staphylococci were isolated from goat's milk, whey and cheese at various stages of manufacture.

Sixteen different coagulase negative Staphylococci (CNS) species were recovered, 3 of which were predominant: Staphylococcus simulans, Staphylococcus epidermidis and Staphylococcus xylosus.

The prevalent species were recovered at least at two different stages of cheese manufacturing, suggesting a better adaptation to the environment. After 15 days of ripening, the cheeses showed lower counts of Micrococcaceae.     

The effect of concentration of chymosin on the yield and sensory properties of camel cheese and on its microbiological quality

The transformation of camel milk into soft cheese by using chymosin and yoghurt starter culture (Streptococcus thermophilus and Lactobacillus bulgaricus) was investigated. The cheese yield and sensory properties were related to the concentration of chymosin. A yield of 16.74 g/100 mL of milk was obtained with a chymosin concentration of 1.7 mL/L of milk. The cheeses obtained with concentrations ranging between 1.0 mL and 2.9 mL of chymosin/L of milk scored highly regarding their sensory properties and had an acceptable microbiological quality. This study demonstrated that cheesemaking from camel milk can be made successfully providing that the appropriate chymosin concentration is used; and that 1.7 mL of chymosin/L of milk was optimal.     

Use of milk protein concentrate to standardize milk composition in Italian citric Mozzarella cheese making

To better exploit manufacturing facilities and standardize cheese quality, milk composition could be standardized by fortifying its protein content with a milk protein concentrate (MPC) addition so avoiding partially skimming the milk. With this aim Mozzarella cheese was obtained adding citric acid into milk standardized at 4% protein and a fat to protein ratio of 1.0. Protein fortification was obtained adding MPC produced by ultrafiltration. Milk, whey, curd, cheese and stretching water were weighed and analysed for total solid, fat and protein content, to measure component recovery and yield. Yield increase (from 13.8% to 16.7%) was due to the higher recovery of the milk total solids and proteins in MPC cheese (48.2 and 78.3%, respectively) and to the slightly higher cheese moisture, obtained with a little modification of the cheese technology when adding MPC. Milk fat in cheese was lower than that reported in literature. Hot water stretching of the curd resulted in very low losses (1%) of protein and considerable losses (14%) of fat for both control and MPC cheeses. The likely reasons of this low recovery are discussed and it can be supposed that a further cheese yield increase is possible by changing the curd stretching procedures.     

Fatty acid profiling of bovine milk and cheese from six European areas by GC‐FID and GC‐MS

The fatty acid (FA) composition of milk from six European areas, as well as the alteration in the FA profile during cheese production, was studied using both a targeted GC‐FID and an untargeted GC‐MS approach. By applying principal component, partial least square discriminant and chemical similarity enrichment analysis, a discrimination of the geographical areas could be achieved highlighting important FA classes such as odd‐ and branched‐chain FAs for the differentiation. The FA profile remained constant during cheese production, and aroma compounds have been identified as biomarkers for the ripening methods used, namely foil and smear ripening.     

Effect of storage time and temperature of milk protein concentrate (MPC85) on the renneting properties of skim milk fortified with MPC85

This study investigated the effect of storage temperature (20–50 °C) and time (0–60 days) on the renneting properties of milk protein concentrate with 85% protein (MPC85). Reconstituted skim milk was fortified with the MPC85 (2.5% w/w) and the renneting properties of the skim milk/MPC85 systems were investigated using rheology. It was found that the final complex modulus (final G∗) and the yield stress of the rennet-induced skim milk/MPC85 gels decreased exponentially with storage time of the MPC85 for storage temperatures greater than 20 °C, with a greater effect at the higher storage temperatures. Changes in the solubility of MPC85 with storage time were correlated with the rheological properties. The primary phase of renneting (cleavage of κ-casein) was not affected by the storage of the MPC85; hence the effect was related to the secondary stage of renneting (aggregation/coagulation of rennet-treated casein micelles). Using a temperature–time superposition method, a master curve was formed from the final G∗, yield stress and solubility results. This suggested that the same physical processes affected the solubility and rennet gelation properties of the milks. It is proposed that the MPC85 protein in rennet-treated skim milk/MPC85 solutions may transform from an interacting material, when solubility is high, to an inert or weakly interacting material, when solubility is low, and that this results in the reduced final G∗ and yield stress of the rennet gels when MPC85 is stored at elevated temperatures for long periods.     

Effect of homogenisation of cheese milk and high‐shear mixing of the curd during cream cheese manufacture

The role of the homogenisation pressure of cheese milk (0, 25, 100 MPa) and high‐shear mixing of cheese curd at different speeds (750, 1500, and 3000 r.p.m.) and times (2 and 4 min) in improving the texture of medium‐fat cream cheese was investigated independently. Homogenisation resulted in small fat globules and firmer texture, while increasing speed and mixing times resulted in a decrease in curd particle size and an increase in the spreadability of the cheese. All curd samples from both the trials exhibited shear‐thinning behaviour. Unhomogenised milk and high‐shear mixing of the curd showed a low coefficient of friction (better lubrication property).     

Effects of freezing and frozen storage on the microstructure and texture of ewe's milk cheese

Semi-hard ewe's milk cheeses, frozen immediately after manufacture either slowly at –35 °C or rapidly at –80 °C and stored at –20 °C for 4 months were studied for microstructural and textural characteristics during subsequent ripening. Two control groups were used to establish the effect of freezing: the fresh unfrozen cheese and cheese thawed immediately after freezing. Freezing proper did not result in any marked changes in the textural parameters of the cheeses, but considerable changes were found in slowly frozen cheeses after 4 months of frozen storage. Shear strength values were lower in all frozen and stored cheeses, particularly in cheese samples frozen slowly compared to those in the unfrozen control batch. This parameter and firmness values were significantly lower in both slowly and rapidly frozen cheeses at the completion of ripening. Ripening tended to offset differences in elasticity, noticeable in the cheeses during the first 30 days of ripening. Light microscopy and electron microscopy revealed small cracks and ruptures in the cheeses which could not be observed by the naked eye. More extensive damage to the cheese microstructure was found in slowly frozen cheese samples stored frozen for 4 months.     

Enterotoxin production by coagulase-negative staphylococci isolated from goats'' milk and cheese

An antigen related to the Enterotoxin E from Staphylococcus aureus was produced by ten of 187 coagulase-negative staphylococci (CNS) isolated from goats' milk, whey and cheese in quantities ranging from 10 to 90 ng/ml supernatant. The enterotoxin-producing strains were identified at the species level as S. simulans, S. xylosus, S. equorum, S. lentus and S. capitis. Detection of the enterotoxins was done by the VIDAS SET test (bioMérieux) and by an indirect double-sandwich ELISA technique using anti-enterotoxin monoclonal antibodies. The results obtained were further confirmed by Southern blotting, using two radioactive oligonucleotide probes that hybridized specifically with the gene of S. aureus coding for the enterotoxin E.