Thermo‐stable semihard Gouda‐type cheese by combining homogenisation and microfiltration of cheese milk

Semihard Gouda‐type cheeses were manufactured at pilot scale using either homogenised milk or homogenised microfiltration retentate. For comparison, cheeses were produced from untreated milk as a Control. Thermo‐physical properties (flowability, stretchability, oiling‐off and browning) were analysed after 4 weeks of ripening. Homogenisation significantly altered the cheese properties, whereas the additional influence of milk pre‐concentration by MF was minor. Compared to the Control, homogenisation led to a significant reduction in flowability, stretchability, oiling‐off and browning. The homogenised fat globules act as active fillers, take part in the protein network and increase the network stability by enhancing protein–protein interactions.     

Effect of activating lactoperoxidase system in cheese milk on the quality of Saint‐Paulin cheese

Saint‐Paulin cheese was made from cow’s milk refrigerated at 4 °C for 72 h and preserved by the lactoperoxidase (LP) system. The effect of the LP system on the microbiological, physicochemical and biochemical properties of cheese over a ripening period of 23 days was investigated, using a control (C0), refrigerated LP‐inactivated cow’s milk (C1) and refrigerated LP‐activated cow’s milk (LPA). The LPA treatment showed the least contamination in flora count, particularly salt‐tolerant bacteria at the end of the ripening period. LPA cheese had significantly lower coliform, yeasts and mould counts (P < 0.05) than the other cheeses; this demonstrated the bacteriostatic effect of the LP system. The proteolysis results showed the least value for LPA cheese as compared with the two other samples, as determined by using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis of casein fractions extracted from the three samples. The findings indicated that the preservation of cow’s cheese milk by the LP system can be used to improve the microbiological quality, inhibit psychotropic germs, correct the losses of soluble nitrogen fractions in the whey and conserve the cheese yield affected by refrigeration.     

The effect of refrigerated storage of raw milk on the physicochemical and microbiological quality of Tunisian semihard Gouda‐type cheese during ripening

A Tunisian semihard Gouda‐type cheese made from milk kept at 4 °C for 24, 48, 72 and 96 h was monitored during 45 days of ripening. The effect of milk refrigeration on the evolution of physicochemical parameters in relation to the quantitative variation of the microbial population during ripening of Gouda‐type cheese was investigated. Microbiological and physicochemical analyses were performed on raw milk and cheese samples after curding, 2, 9, 16, 23, 30, 37 and 45 days of ripening time. The raw milk kept under refrigeration at 4 °C for 96 h showed the highest microbial count and proteolysis level. The duration of storage significantly reduced the cheese yield as a result of important solubilisation casein in proteoses‐peptones. Results of different nitrogenous fractions by Kjeldahl method showed enzymatic hydrolysis products of casein whose intensity depended on the maturing stage as well as the refrigeration time. Besides the evident action of the plasmin, original milk protease, on the hydrolysis of casein in soluble fractions, the proteolysis of cheese caseins is also initiated by proteolytic action of the chymosin and extracellular heat‐resistant proteases notably produced by the same psychrotrophic microflora. Lactic acid bacteria starters that constitute the dominant microflora of this type of cheese are also considered as aroma precursors.     

Salt reduction in film‐ripened,semihard Edam cheese

As a potential measure to improve public health, this study aimed to reduce the sodium (Na) content of film‐ripened, semihard Edam cheese to ≤0.4 g Na/100 g (≤1 g NaCl/100 g), while retaining typical quality and safety characteristics. For this, mineral salt substitutions containing potassium (K) were compared with simple NaCl reduction in brine, alongside an adjustment of starter cultures in an effort to enhance taste. Desired Na and K values were achieved, and microbial quality was not compromised in Na‐reduced Edam after six weeks of ripening. However, all Na‐reduced cheeses tasted bitter and were therefore organoleptically unsatisfactory.     

X-ray images for the control of eye formation in cheese

There is demand for non-destructive monitoring of eye formation in cheese during ripening. The objective of this work was to develop a simple method based on existing equipment in the dairy industry. Images were acquired using a conventional, low resolution online X-ray instrument. Image processing methods for detecting eyes of cheese and measuring volume and size distribution were developed. Sufficient detection of overlapping eyes was obtained. Semihard cheese with propionibacteria ripened under different conditions was analysed. The method was found promising for quality control as it will make possible non-destructive monitoring of eye formation of cheese throughout the ripening period.     

Behaviour of Listeria monocytogenes in Lighvan cheese following artificial contamination during making,ripening and storage in different conditions

This study investigated the behaviour and fate of Listeria monocytogenes at different ripening temperatures and NaCl concentrations in traditional Lighvan cheese. L. monocytogenes was added to raw sheep's milk. After producing the cheese, they were stored in 8%, 12% and 15% NaCl at 4, 9 and 14 °C. Sampling was performed for 150 days. Different temperature and NaCl concentrations had a significant effect on the survival of L. monocytogenes (P < 0.001). The lowest growth and survival rates of L. monocytogenes were in 15% NaCl at 14 °C and 12% NaCl at 14 °C, respectively. Also, the highest growth and survival rates of the bacterium were in 8% NaCl at 4 °C.     

Impact of physiological state of starter culture on ripening and flavour development of Swiss–Dutch‐type cheese

The changes in the physiological state and metabolism of starter culture in 15kg Swiss–Dutch‐type cheese blocks during two‐stage ripening were studied. The analyses were performed on samples from three layers of cheese between the rind and the core. Cell membrane integrity, intracellular esterase activity and bacteria culturability were chosen as physiological state indicators. Cheese flavour development was determined by static headspace gas chromatography. During warm room ripening, the number of cells with intact cell membranes and displaying intracellular esterase activity increased. Lactic acid bacteria underwent resuscitation and regained their culturability. A lack of homogeneity within the cheese was noticed in relation to bacterial activity and the volatiles concentration.     

The influence of ripening temperature and sampling site on the proteolysis in Reggianito Argentino cheese

The effects of elevated ripening temperature and sampling site on proteolysis in Reggianito Argentino cheese were evaluated. Cheeses ripened at 12 or 18 °C and 85% relative humidity were analysed at 2, 4 and 6 months in 2 sampling zones (central and external). Samples were analysed to determine the physicochemical and proteolysis parameters through the urea-PAGE of the urea-soluble fraction, RP-HPLC analysis of the water-soluble fraction at pH 4.6, and the free amino acid analysis. Proteolysis was significantly affected by ripening temperature and sampling site. Urea-PAGE analysis showed that elevated temperature increased the degradation of α_s1- and β-casein. The degradation of α_s1-casein was larger in the central zone than in the external one, while β-casein degradation was similar in both zones. The majority peaks detected by RP-HPLC of the water-soluble fraction at pH 4.6 and free amino acids were significantly affected by ripening temperature and sampling site. Glu, His, Val, Leu, and Lys had the higher concentrations. Principal component analysis showed useful groupings when results from chromatograms were studied. In conclusion, the results obtained not only are useful to characterise the ripening of an Argentinean hard cheese, but also to evaluate the effect of an increase of ripening temperature on Reggianito Argentino cheese proteolysis.     

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.     

The influence of ripening temperature and sampling site on the lipolysis in Reggianito Argentino cheese

The effect of ripening temperature elevation and sampling site on lipolysis in Reggianito Argentino cheese was evaluated. Cheeses ripened at 12 or 18 °C and 85% relative humidity were assayed at 2, 4 and 6 months at two sampling zones (central and external). Samples were analysed to determine physicochemical parameters and the concentration of nine free fatty acids (FFAs) (C_6:0–C_18:2). Myristic, palmitic, stearic and oleic acids were found in higher concentration. While ripening time and temperature significantly affected the concentrations of the nine FFAs analysed, sampling zone significantly affected only two FFAs. Ripening temperature increased the lipolytic process, but it seems to have no effect on the pathways of lipolysis in Reggianito Argentino cheese.     

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.     

The effect of coagulant type on yield and sensory properties of semihard cheese from laboratory‐, pilot‐ and commercial‐scale productions

Using calf rennet or a commercial microbial rennet substitute derived from Rhizomucor miehei cheesemaking experiments were performed at laboratory and pilot scale, and at commercial scale in two industrial dairy plants during regular production. At all levels of scale, the solids transfer from milk to curd was significantly higher (0.50–1.19%) when using calf rennet. There were significant differences in levels of proteolysis during maturation and in levels of bitterness at 12 weeks of ripening between Gouda cheeses produced with calf rennet or with commercial rennet substitute at pilot and at commercial scale.     

Soya bean oil/soya protein isolate and carrageenan emulsions as fat replacer in fat‐reduced Oaxaca‐type cheese

Milk fat was replaced in Oaxaca‐type cheese with soya bean oil emulsions stabilised with soya protein isolate and different carrageenans (kappa, iota and lambda). Inclusion of soya bean oil emulsion increased yield, moisture and protein content and reduced fat content. Fat reduction and moisture incorporation provoked a tougher but less ductile texture. Specific interaction of carrageenans with milk proteins resulted in larger spreading area when melted and a softer and more adhesive texture, particularly in samples containing lambda‐carrageenan. These results are useful to improve the nutritional composition of Oaxaca‐type cheese, allowing the control of textural properties during cheese melting.     

Influence of storage,brine concentration and in‐container heat treatment on the stability of white brined Nabulsi cheese

Microbial levels were significantly (P < 0.05) affected by the temperature‐time treatments used during in‐container heat treatment of the curd, brine concentration and storage duration. A heat treatment of 115 °C × 2 min, in the absence of NaCl, was sufficient to eliminate Mesophilic micro‐organisms, Coliforms, Staphylococcus aureus and Yeast and Moulds for the duration of 1 year of storage. Sensory scores for colour, appearance and texture increased significantly (P < 0.05) with the increase in the NaCl in brine concentration regardless of the temperature‐time treatment.     

A comparative biochemical study of two industrially produced short‐ripened cow's milk cheeses with PDO status: Rennet‐curd Tetilla cheese and acid‐curd Cebreiro cheese

The aim of this study was to characterise industrial Tetilla and Cebreiro Protected Designation of Origin (PDO) Spanish cheeses from a biochemical point of view and to relate some of the biochemical parameters to the cheesemaking process. Some differences in the amounts of organic acids and free amino acids between the two types of cheese were attributed to milk characteristics and the processing technology. The most abundant volatile compounds in both types of cheese were ethanol, isopropanol and diacetyl. The simple and nonspecific volatile profiles of the cheeses appear to be related to the commercial mesophilic DL‐starters used in the manufacturing process.     

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.     

The effect of varying casein/fat ratio on physicochemical and sensory qualities of Feta‐type cheese made using buffalo milk

The Feta‐type cheese was prepared with different casein/fat (C/F) ratios of buffalo milk using microbial rennet. The manufactured Feta cheeses were subjected to physicochemical and sensory quality at 15‐day interval up to 60 days of ripening. Sensory analysis discriminated the different level of C/F ratio of buffalo milk cheeses predominantly by age. There was no significant difference (P < 0.01) observed in cheese made from C/F ratio of 0.6–0.7 in terms of flavour. The titratable acidity (TA), soluble protein and free fatty acid appear to be age‐dependent and increased throughout the ripening in all experimental cheeses.     

The effects of starter cultures on chemical,biochemical and sensory properties of low‐fat Tulum cheeses during ripening

Three different commercial starter cultures, Choozit^? MA 11 (MA ), Choozit^? BT 01 (BT ) and Choozit^? Feta A (Feta), were used to remedy textural and aromatic defects and improve the overall quality of low‐fat Tulum cheeses. Chemical and sensory analyses as well as electrophoresis were performed. Supplemental yoghurt bacteria and Lactobacillus helveticus were found to be key contributors in proteolysis with varying protein breakdown capacities. The results suggest that using appropriate culture combinations could result in low‐fat Tulum cheeses with better sensory characteristics and proteolysis rates.     

The effect of two types of mould inoculants on the microbiological composition,physicochemical properties and protein hydrolysis in two Gorgonzola‐type cheese varieties during ripening

The aim of this paper was to investigate the role of two types of Penicillium roqueforti moulds (type esportazione and dolce) in the ripening of two Gorgonzola‐type cheese varieties. Cheeses were analysed after 4, 14, 30 and 60 days of ripening. Microbiological analysis showed high numbers of total bacterial count, yeasts and moulds in both 60‐day‐old cheese varieties. The concentration of water‐soluble N, nonprotein N and 5% phosphotungstic acid‐soluble N increased significantly during ripening. Patterns of proteolysis by urea‐polyacrylamide gel electrophoresis showed that rind‐to‐core gradients and age‐related changes in moisture and salt content influenced mould and other enzyme activities, which are reflected in various rates of protein degradation. The hydrolysis of αs₁‐ and β‐caseins was more extensive in the core than under the rind of both cheese varieties.     

Influence of the sunflower oil content,cooking temperature and cooking time on the physical and sensory properties of spreadable cheese analogues based on UF white‐brined cheese

In this study, a cheese analogue was produced based on UF white‐brined cheese by replacing the dairy fat with sunflower oil and cooking at different temperatures and times. Hardness, adhesiveness, meltability and oiling‐off were used to evaluate the suitability of the final product. Partial replacement of dairy cream with sunflower oil led to an increase in the adhesiveness, oiling‐off and spreadability while decreasing the hardness of the cheese. Optimum operating conditions were found to be 85 °C for the cooking temperature, 14.12 min for the cooking time and 27.14% w/w for the sunflower oil content.