Cheese-Matrix Characteristics During Heating and Cheese Melting Temperature Prediction by Synchronous Fluorescence and Mid-infrared Spectroscopies

The structure and rheology characteristics of Comté (hard cheese) and Raclette (semihard cheese) cheeses as a function of temperature were investigated using dynamic testing rheology and mid-infrared and synchronous front-face fluorescence spectroscopies. The storage modulus (G′), the loss modulus (G″), and the complex viscosity (η*) decreased while strain and phase angle (tan δ) increased as the temperature increased from 20 to 80 °C. SF (250–500 nm with Δλ = 80) and MIR (3,000–2,800 (fat region), 1,700–1,500 (protein region), and 1,500–900 cm⁻¹ (fingerprint region)) spectra were recorded on cheese samples at 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 °C. The results showed that each spectroscopic technique provided relevant information related to the cheese protein and fat structures during melting, allowing the investigation of structural changes. In addition, the melting temperatures of cheese matrices and fats of the two cheeses were determined from the dynamic rheology data, SF spectra, and MIR spectra. Similar temperatures were obtained whatever the technique, since values of about 60 and 31 °C were obtained for matrix and fat melting temperatures of Comté and Raclette cheeses, respectively. No significant difference was observed between the results obtained with the three methods (significance level of 5%).     

A comparison and joint use of mid infrared and fluorescence spectroscopic methods for differentiating between manufacturing processes and sampling zones of ripened soft cheeses

Ten traditional M1 (n = 5) and M2 (n = 5) soft cheeses produced from raw milk, and five other stabilised M3 (n = 5) cheeses manufactured from pasteurised milk, were studied using mid infrared (MIR) and front face fluorescence (FFFS) spectroscopies. MIR (3000–900 cm⁻¹), tryptophan (excitation: 290 nm, emission: 305-450 nm), 400-640 emission spectra (excitation: 380 nm) and vitamin A (excitation: 280–350 nm, emission: 410 nm) spectra were recorded at two sampling zones (external (E) and central (C)) of the investigated cheeses. When the factorial discriminant analysis (FDA) was applied to the MIR spectra, the classification was not satisfactory. With tryptophan fluorescence spectra, correct classification of 94.4 and 69.4% was observed for the calibration and validation spectra, respectively. Better classification was obtained using vitamin A fluorescence spectra, since 91.8 and 80.6% of the calibration and validation spectra, respectively, were correctly classified. When the first five principal components (PCs) of the PCA extracted from each data set were pooled into a single matrix and analysed by FDA, the classification was considerably improved, obtaining a percentage of correct classification of 100 and 91.7% for the calibration and validation samples, respectively. It was concluded that concatenation of the physico-chemical and spectroscopic data sets is an efficient technique for the identification of soft cheese varieties.     

Monitoring the geographic origin of both experimental French Jura hard cheeses and Swiss Gruyère and L’Etivaz PDO cheeses using mid-infrared and fluorescence spectroscopies: a preliminary investigation

The potential of mid-infrared and intrinsic fluorescence spectroscopies was investigated for determining the geographic origin of different hard cheeses. Mid-infrared (1700–1500 cm⁻¹ region), fluorescence emission spectra, following excitation at 250 and 290 nm, and fluorescence excitation spectra following emission at 410 nm were recorded directly on cheese samples. Twelve experimental hard cheeses were made using identical and controlled cheese-making conditions with milks originating from three different regions in Jura (France). The results of factorial discriminant analysis (FDA) performed on the fluorescence and mid-infrared spectra of the experimental cheeses showed a good discrimination of the cheeses.In a second step, 25 Gruyère Protected Denomination of Origin (PDO) cheeses manufactured at different altitudes in Switzerland, i.e., 11 Gruyère PDO cheeses from the lowlands (<800 m), eight Gruyère PDO cheeses from the highlands (1100–1500 m) and six L’Etivaz PDO cheeses (1500–1850 m) were analysed. Only 80% of correct classification was obtained by applying FDA to the mid-infrared spectra of the investigated cheeses. A better classification (100%) was achieved based on the fluorescence spectra. Front-face fluorescence spectroscopy appeared to be rapid, low cost and efficient for the geographic determination of Gruyère cheeses.     

Feasibility study of discriminating the manufacturing process and sampling zone in ripened soft cheeses using attenuated total reflectance MIR and fiber optic diffuse reflectance VIS–NIR spectroscopy

The use of visible–near infrared (VIS–NIR) and mid infrared (MIR) spectroscopies for rapid characterisation of 15 traditional and stabilised retail soft cheeses, manufactured with different cheese making procedures was described. A fiber-type, VIS–NIR spectrophotometer (Zeiss Corona 45 VIS–NIR) in a measurement range of 315–1700 nm and a Fourier transform spectrometer (IFS 66V/S, Bruker, Belgium) in a measurement range between 3000 and 900 cm⁻¹ were used to scan spectra in reflectance mode at the external (E) and central (C) zones of the investigated cheeses. The principal component analysis (PCA) applied to the normalised spectral data set (VIS–NIR and MIR) did not provide a good discrimination of cheeses. Therefore, the factorial discriminant analysis (FDA) was applied separately to the first 5 principal components (PCs) of the PCA performed on the VIS–NIR and MIR data sets. Regarding the MIR spectra, the percentage of samples correctly classified into six groups (three for the E and three for the C zones) by the FDA was 64.8% and 33.3% for the calibration and validation samples, respectively. Better classification was obtained from the VIS–NIR spectra since the percentage of samples correctly classified was 85.2% and 63.2% for the calibration and validation samples, respectively. Finally, a concatenation technique was applied on the first 5 PCs of the PCA performed on the VIS–NIR and MIR data sets. This technique allowed a quite satisfactory classification of the investigated cheeses according to their manufacturing process and their sampling zone. In this case, correct classifications (CC) of 90.7% and 80.6% were obtained for the calibration and the validation samples, respectively.     

Dynamic testing rheology and fluorescence spectroscopy investigations of surface to centre differences in ripened soft cheeses

The viscoelastic properties and the matrix structures of three different retailed soft cheeses (M1, M2 and M3), for which the manufacturing process was varied, were studied from the surface to the centre of the cheese using dynamic rheology and front-face fluorescence spectroscopy. The storage modulus (G′) and the loss modulus (G″) values of the samples increased from the surface to the inner part of the cheeses, while strain and tan δ decreased. Protein tryptophan (excitation: 290 nm; emission: 305–400 nm) and vitamin A (emission: 410 nm; excitation: 250–350 nm) spectra were recorded at 20°C in samples cut from the surface to the centre. For each cheese, the data sets containing fluorescence spectra and rheology data were evaluated using multidimensional statistical methods. In addition, the three cheeses were well discriminated by their spectra by applying factorial discriminant analysis. From the tryptophan fluorescence data sets, 94% and 87.7% good classifications were observed for calibration and validation groups, respectively. A better classification (100% and 96% for principal and test samples) was obtained from the vitamin A spectra. Canonical correlation analysis was performed on the rheology and tryptophan fluorescence spectral data sets, and on the rheology and vitamin A fluorescence spectra data sets. The two groups of variables were found to be highly correlated since the squared canonical coefficients for canonical variates 1, 2, 3, 4 were higher than 0.98. These high correlations indicate that cheese rheology is a reflection of its structure at the molecular level.     

Determining the geographic origin of Emmental cheeses produced during winter and summer using a technique based on the concatenation of MIR and fluorescence spectroscopic data

A technique that used multivariate data analysis to combine mid-infrared (MIR) spectroscopy with front-face fluorescence spectroscopy was used to discriminate between Emmental cheeses originating from different European countries: Austria (n=12), Finland (n=10), Germany (n=19), France (n=57), and Switzerland (n=65). In total, 163 Emmental cheeses produced in winter (n=91) and summer (n=72) periods were investigated. When Factorial Discriminant Analysis was applied to either the infrared or fluorescence spectral data the classifications were not satisfactory. Therefore, the first twenty principal components (PCs) of the PCA extracted from each data set (MIR and tryptophan fluorescence spectra) were pooled (concatenated) into a single matrix and analysed by Factorial Discriminant Analysis. Correct classifications were obtained for the samples for 89% of the calibration spectra and 76.7% of the validation spectra. The discrimination for cheeses from Finland was excellent, while Austrian, German, French and Swiss cheeses were also discriminated well although a few samples were misclassified. It was concluded that concatenation of the data from the two spectroscopic techniques is an efficient technique for authenticating Emmental cheeses independently of their manufacturing period.     

Monitoring the molecular changes by front face fluorescence spectroscopy throughout ripening of a semi-hard cheese

Twenty four semi-hard cheeses produced during autumn (n = 12) and summer (n = 12) periods were manufactured and ripened at an industrial scale. Tryptophan and vitamin A fluorescence spectra were scanned on the 24 cheeses at 2, 30 and 60 days of ripening. Principal component analysis (PCA) and factorial discriminant analysis (FDA) were applied on the spectral data sets. The first five principal components (PCs) of the PCA extracted from each data set (tryptophan or vitamin A) of cheeses produced during autumn or summer period were pooled into a single matrix and analysed by FDA. Regarding cheeses produced during the autumn period, the percentage of samples correctly classified was 95.8% and 86.1% for the calibration and validation samples, respectively. Similar results were obtained from cheeses produced during the summer period. Finally, concatenation technique was applied to the tryptophan and vitamin A spectra recorded on cheeses independently of their production seasons. Correct classification was observed for 87.5% and 80.6% for the calibration and validation samples, respectively. Although this statistical technique did not allow 100% correct classification for all groups, the results obtained were promising considering the significant effect of the season on the cheese characteristics.     

Characterisation of Emmental Cheeses Within Different Brand Products by Combining Infrared and Fluorescence Spectroscopies

The potential of spectroscopic (i.e. mid-infrared and front-face fluorescence) and physicochemical methods combined with chemometric tools was investigated for discriminating Emmental cheeses produced in different regions of France. A total of 20 French Emmental cheeses belonging to different brand products were studied. When principal component analysis was applied separately to each used technique, the discrimination of cheeses was not satisfactory. Therefore, common components and specific weight analysis was applied to the whole data sets: the second common component (q ₂), discriminating cheeses of producer C from the others, expressed 78 and 23 % of the inertia of the vitamin A and tryptophan, respectively. On the contrary, the third common component (q ₃), discriminating cheeses as a function of their ripening time and/or their manufacturing process procedure, expressed 15, 30, and 16 % of the inertia of the 3,000–2,800, 1,700–1,500 and 1,500–900 cm^?1 spectral region. The infrared and fluorescence spectral patterns allowed molecular interpretation and identification of Emmental cheeses according to their both manufacturing process and brand products.     

Prediction of the rheology parameters of ripened semi-hard cheeses using fluorescence spectra in the UV and visible ranges recorded at a young stage

Storage modulus (G′), loss modulus (G″), strain, tan (δ) and complex viscosity (η*) of 20 semi-hard cheeses were measured by dynamic oscillatory analysis after 2, 30 and 60 days of ripening. On the same cheeses and at the same ages, tryptophan and riboflavin fluorescence spectra were recorded. The aim was to predict the rheology parameters of ripened cheeses from spectra recorded on these cheeses at a young stage. Using partial least square, tryptophan fluorescence spectra recorded at 20 °C on 2-days-old cheeses predicted G′, G″, strain, tan (δ) and η* measured at 80 °C on the 60-days-old cheeses with correlation coefficients (R) of 0.98, 0.97, 0.98, 0.98 and 0.97, respectively. Riboflavin fluorescence spectra gave slightly lower correlation coefficients of 0.88, 0.88, 0.92, 0.87 and 0.88, respectively. Dependent only on visible light, the riboflavin fluorescence spectra potentially provide viable and economic prediction of the rheology of ripe cheese.     

Phase transition of triglycerides during semi-hard cheese ripening

Sixteen semi-hard cheeses varying by their protein (20.2–24.1%), fat (23.7–31.1%) and dry matter (50.2–57.9%) contents were manufactured and ripened in controlled conditions. Fluorescence (vitamin A) and mid-infrared (2780–3000 cm⁻¹ region) spectra were collected on the 16 different cheeses at 1, 21, 51 and 81 days of ripening. The data tables containing the mid-infrared and fluorescence spectra of the different cheeses were analyzed by principal component analysis and canonical correlation analysis methods. The obtained similarity maps showed that it was possible to discriminate the cheeses at the four different ripening times from the infrared and fluorescence spectra. In addition, the interest to combine the two spectroscopies was demonstrated since a better discrimination of the four stages was obtained using canonical correlation analysis. The examination of the spectral patterns associated with the principal components and the canonical variates showed that the structure of triglycerides acyl chains in fat globules was modified during cheeses ripening. The shift of the methylene bands in the infrared region and the changes of the shape of vitamin A fluorescence spectra agree with partial crystallization of triglycerides from 21 to 81 days of storage.     

Utilisation of mid-infrared spectroscopy for determination of the geographic origin of Gruyère PDO and L’Etivaz PDO Swiss cheeses

The potential of mid-infrared spectroscopy (MIR), using an attenuated total reflectance (ATR) cell, was evaluated for the authentication of 25 Gruyère PDO and L’Etivaz PDO cheeses produced at different altitudes in Switzerland. In order to test the ability of MIR to authenticate the investigated cheeses, chemometric tools, such as principal component analysis (PCA) and factorial discriminant analysis (FDA), were applied to the three spectral regions of the MIR (e.g. 3000–2800 cm⁻¹, 1700–1500 cm⁻¹, and 1500–900 cm⁻¹). By applying the FDA to the first 10 principal components (PCs) of the PCA applied to each spectral regions, the best rate of correct classification was obtained in the 3000–2800 cm⁻¹ and 1500–900 cm⁻¹ spectral regions, since 90.5% and 90.9% were achieved, respectively. It can be concluded that these two spectral regions could be considered as valuable tools for the determination of the geographical origin of the investigated cheeses.     

Determination of fat,protein, moisture,and salt content of Cheddar cheese using mid-infrared transmittance spectroscopy

The objective of our work was to develop and evaluate the performance of a rapid method for measuring fat, protein, moisture, and salt content of Cheddar cheese using a combination mid-infrared (MIR) transmittance analysis and an in-line conductivity sensor in an MIR milk analyzer. Cheddar cheese was blended with a dissolving solution containing pentasodium triphosphate and disodium metasilicate to achieve a uniform, particle-free dispersion of cheese, which had a fat and protein content similar to milk and could be analyzed using a MIR transmittance milk analyzer. Annatto-colored Cheddar cheese samples (34) from one cheese factory were analyzed using reference chemistry methods for fat (Mojonnier ether extraction), crude protein (Kjeldahl), moisture (oven-drying total solids), and salt (Volhard silver nitrate titration). The same 34 cheese samples were also dissolved using the cheese dissolver solution, and then run through the MIR and used for calibration. The reference testing for fat and crude protein was done on the cheese after dispersion in the dissolver solution. Validation was done using a total of 36 annatto-colored Cheddar cheese samples from 4 cheese factories. The 36 validation cheese samples were also analyzed using near-infrared spectroscopy for fat, moisture, and the coulometric method for salt in each factory where they were produced. The validation cheeses were also tested using the same chemical reference methods that were used for analysis of the calibration samples. Standard error of prediction (SEP) values for moisture and fat on the near-infrared spectroscopy were 0.30 and 0.45, respectively, whereas the MIR produced SEP values of 0.28 and 0.23 for moisture (mean 36.82%) and fat (mean 34.0%), respectively. The MIR also out-performed the coulometric method for salt determination with SEP values of 0.036 and 0.139 at a mean level of salt of 1.8%, respectively. The MIR had an SEP value of 0.19 for estimation at a mean level of 24.0% crude protein, which suggests that MIR could be an easy and effective way for cheese producers to measure protein to determine protein recovery in cheese making.     

Effect of Guar Gum on the Physicochemical, Thermal, Rheological and Textural Properties of Green Edam Cheese

In attempts to produce a low-fat cheese with a rheology and texture similar to that of a full-fat cheese, guar gum (within 0.0025–0.01%; w/v, final concentration) was added to low-fat milk. The obtained cheeses were characterised regarding their physicochemical, thermal, rheological and textural properties. Control cheeses were also produced with low and full-fat milk. The physicochemical properties of the guar gum modified cheeses were similar to those of the low-fat control. No significant differences were detected in the thermal properties (concerning the enthalpy and profile of water desorption) among all types of cheeses. The rheological behaviour of the 0.0025% modified cheese was very similar to the full-fat control. Overall, no trend was observed in the texture profile (hardness, cohesiveness, gumminess and elasticity) of the modified cheeses versus guar gum concentration, as well as in comparison with the control groups, suggesting that none of the studied polysaccharide concentrations simulated the textural functions of fat in Edam cheese.     

Genetic parameters for cheese-making properties and milk composition predicted from mid-infrared spectra in a large data set of Montbéliarde cows

Cheese-making properties of pressed cooked cheeses (PCC) and soft cheeses (SC) were predicted from mid-infrared (MIR) spectra. The traits that were best predicted by MIR spectra (as determined by comparison with reference measurements) were 3 measures of laboratory cheese yield, 5 coagulation traits, and 1 acidification trait for PCC (initial pH; pH_0PPC). Coefficients of determination of these traits ranged between 0.54 and 0.89. These 9 traits as well as milk composition traits (fatty acid, protein, mineral, lactose, and citrate content) were then predicted from 1,100,238 MIR spectra from 126,873 primiparous Montbéliarde cows. Using this data set, we estimated the corresponding genetic parameters of these traits by REML procedures. A univariate or bivariate repeatability animal model was used that included the fixed effects of herd × test day × spectrometer, stage of lactation, and year × month of calving as well as the random additive genetic, permanent environmental, and residual effects. Heritability estimates varied between 0.37 and 0.48 for the 9 cheese-making property traits analyzed. Coagulation traits were the ones with the highest heritability (0.42 to 0.48), whereas cheese yields and pH_{0 PPC} had the lowest heritability (0.37 to 0.39). Strong favorable genetic correlations, with absolute values between 0.64 and 0.97, were found between different measures of cheese yield, between coagulation traits, between cheese yields and coagulation traits, and between coagulation traits measured for PCC and SC. In contrast, the genetic correlations between milk pH_{0 PPC} and CY or coagulation traits were weak (?0.08 to 0.09). The genetic relationships between cheese-making property traits and milk composition were moderate to high. In particular, high levels of proteins, fatty acids, Ca, P, and Mg in milk were associated with better cheese yields and improved coagulation. Proteins in milk were strongly genetically correlated with coagulation traits and, to a lesser extent, with cheese yields, whereas fatty acids in milk were more genetically correlated with cheese yields than with coagulation traits. This study, carried out on a large scale in Montbéliarde cows, shows that MIR predictions of cheese yields and milk coagulation properties are sufficiently accurate to be used for genetic analyses. Cheese-making traits, as predicted from MIR spectra, are moderately heritable and could be integrated into breeding objectives without additional phenotyping cost, thus creating an opportunity for efficient improvement via selection.     

Contribution of fluorescence spectroscopy and independent components analysis to the evaluation of NaCl and KCl effects on molecular-structure and fat melting temperatures of Cantal-type cheese

One of the main objectives of the present study was to investigate by different analytical techniques (physicochemical analysis, dynamic rheology, and synchronous fluorescence spectroscopy) the impact of the NaCl reduction and its substitution by KCl on the molecular structure and fat melting of Cantal-type cheese. Molecular structure changes were investigated on five cheese sample formulations from 20 to 60 °C with five offsets using SF spectroscopy coupled with independent components analysis. Results showed that significant differences were observed for protein, Cl, Ca, Na and K contents of cheeses. Complex viscosity decreased as the temperature increased for the different cheeses. SF spectroscopy provided relevant information related to protein and fat structures with varying salt concentrations and type during melting, allowing investigation of molecular structure changes of the cheeses. In addition, similar fat melting temperatures for each cheese were obtained regardless the technique used (dynamic rheology and fluorescence).     

Effect of type of concentrated sweet cream buttermilk on the manufacture, yield, and functionality of pizza cheese

Sweet cream buttermilk (SCB) is a rich source of phospholipids (PL). Most SCB is sold in a concentrated form. This study was conducted to determine if different concentration processes could affect the behavior of SCB as an ingredient in cheese. Sweet cream buttermilk was concentrated by 3 methods: cold ( < 7°C) UF, cold reverse osmosis (RO), and evaporation (EVAP). A washed, stirred-curd pizza cheese was manufactured using the 3 different types of concentrated SCB as an ingredient in standardized milk. Cheesemilks of casein:fat ratio of 1.0 and final casein content ∼2.7% were obtained by blending ultrafiltered (UF)-SCB retentate (19.9% solids), RO-SCB retentate (21.9% solids), or EVAP-SCB retentate (36.6% solids) with partially skimmed milk (11.2% solids) and cream (34.6% fat). Control milk (11.0% solids) was standardized by blending partially skimmed milk with cream. Cheese functionality was assessed using dynamic low-amplitude oscillatory rheology, UW Meltprofiler (degree of flow after heating to 60°C), and performance of cheese on pizza. Initial trials with SCB-fortified cheeses resulted in ∼4 to 5% higher moisture (51 to 52%) than control cheese (∼47%). In subsequent trials, procedures were altered to obtain similar moisture content in all cheeses. Fat recoveries were significantly lower in RO- and EVAP-SCB cheeses than in control or UF-SCB cheeses. Nitrogen recoveries were not significantly different but tended to be slightly lower in control cheeses than the various SCB cheeses. Total PL recovered in SCB cheeses (∼32 to 36%) were lower than control (∼41%), even though SCB is high in PL. From the rheology test, the loss tangent curves at temperatures > 40°C increased as cheese aged up to a month and were significantly lower in SCB cheeses than the control, indicating lower meltability. Degree of flow in all the cheeses was similar regardless of the treatment used, and as cheese ripened, it increased for all cheeses. Trichloroacetic acid-soluble N levels were similar in the control and SCB-fortified cheese. On baked pizza, cheese made from milk fortified with UF-SCB tended to have the lowest amount of free oil, but flavor attributes of all cheeses were similar. Addition of concentrated SCB to standardize cheesemilk for pizza cheese did not adversely affect functional properties of cheese but increased cheese moisture without changes in manufacturing procedure.     

Influence of processing parameters on the texture and microstructure of imitation cheese

In this study the impact of cooker design and/or blade/auger speed on the functional properties of imitation cheese was investigated. Cheeses with similar compositions (48% moisture) were manufactured using water, rennet casein, rapeseed and hydrogenated palm oil and emulsifying salts in a twin-screw (Blentech) or a single-blade cooker (Stephan). The cookers were operated at auger speeds of 750, 1,125 or 1,500 (Stephan) or 100 or 200 rpm (Blentech). Increasing the blade speed of the Stephan increased (P < 0.001) the hardness and decreased the meltability of imitation cheese from 112 to 66 mm respectively. Hardness and meltability values of cheeses made in the Blentech cooker were only slightly affected by auger speed. The cheese made in the Stephan at 1,500 rpm had the highest G′ and G′′ values at 25 °C of all the cheeses. This study shows that imitation cheese with acceptable functional properties can be successfully manufactured in a single-blade cooker operated at moderate speeds.     

Utilization of interesterified fat in the production of Turkish white cheese

The chemical, physicochemical, proteolysis, sensory, and texture characteristics of white cheeses made from interesterified fat were examined throughout ripening for 90 days. The water-soluble nitrogen based ripening indexes of cheeses increased throughout the ripening period. However, there were not large quantitative differences between the peptide profiles of the all cheese samples. Cheeses produced by using fully interesterified fat had higher values for hardness, chewiness, and gumminess than that of control cheese (p<0.05). The polyunsaturated to saturated fatty acid ratios of cheeses were increased due to the presence of interesterified fat. The cholesterol values of cheeses decreased at the rate of between 58.83–89.04% depending on interesterified fat addition. In the sensory analysis, similar scores were obtained for both the control cheese and the other cheeses. The results showed that interesterified fat in cheese production could be used to fully or partially replace the milk fat in cheese.     

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.