Relationships between cheese-processing conditions and curd and cheese properties to improve the yield of Idiazabal cheese made in small artisan dairies: A multivariate approach

Very diverse cutting and cooking intensity processes are currently used in small artisan dairies to manufacture Idiazabal cheese. The combination of the technical settings used during cheese manufacturing is known to affect cheese composition and yield, as well as whey losses. However, the information regarding the effect on microstructure and texture of cheese is scarce, especially in commercial productions. Therefore, the effect of moderate- and high-intensity cutting and cooking processes on whey losses, curd-grain characteristics, microstructure and cheese properties, and yield were analyzed. Three trials were monitored in each of 2 different small dairies during the cheesemaking of Idiazabal cheese, which is a semihard cheese made from raw sheep milk. The role and know-how of the cheesemakers are crucial in these productions because they determine the cutting point and handle semi-automatic vats. The 2 dairies studied used the following settings: dairy A used moderate-intensity cutting and cooking conditions, and dairy B used high-intensity cutting and cooking settings. Multiple relationships between cheese-processing conditions and curd, whey, and cheese properties as well as yield were obtained from a partial least square regression analysis. An increased amount of fat and casein losses were generated due to a combination of an excessively firm gel at cutting point together with high-intensity cutting and cooking processes. The microstructural analysis revealed that the porosity of the protein matrix of curd grains after cooking and cheese after pressing was the main feature affected, developing a less porous structure with a more intense process. Moderate-intensity cutting and cooking processes were associated with a higher cheese yield, regardless of the longer pressing process applied. No significant differences were observed in cheese composition. After 1 mo of ripening, however, the cheese was more brittle and adhesive when the high-intensity cutting and cooking process was applied. This could be associated with the composition, characteristics, and size distribution of curd grains due to differences in the compaction degree during pressing. These results could help to modify specific conditions used in cheesemaking, especially improving the process in those small dairies where the role of the cheesemaker is crucial.     

Effect of goat milk composition on cheesemaking traits and daily cheese production

Cheese yield is strongly influenced by the composition of milk, especially fat and protein contents, and by the efficiency of the recovery of each milk component in the curd. The real effect of milk composition on cheesemaking ability of goat milk is still unknown. The aims of this study were to quantify the effects of milk composition; namely, fat, protein, and casein contents, on milk nutrient recovery in the curd, cheese yield, and average daily yield. Individual milk samples were collected from 560 goats of 6 different breeds. Each sample was analyzed in duplicate using the 9-laboratory milk cheesemaking assessment, a laboratory method that mimicked cheesemaking procedures, with milk heating, rennet addition, coagulation, curd cutting, and draining. Data were submitted to statistical analysis; results showed that the increase of milk fat content was associated with a large improvement of cheese yield because of the higher recovery of all milk nutrients in the curd, and thus a higher individual daily cheese yield. The increase of milk protein content affected the recovery of fat, total solids, and energy in the curd. Casein number, calculated as casein-to-protein ratio, did not affect protein recovery but strongly influenced the recovery of fat, showing a curvilinear pattern and the most favorable data for the intermediate values of casein number. In conclusion, increased fat and protein contents in the milk had an effect on cheese yield not only for the greater quantity of nutrients available but also for the improved efficiency of the recovery in the curd of all nutrients. These results are useful to improve knowledge on cheesemaking processes in the caprine dairy industry.     

Segmentation of Parmigiano Reggiano dairies according to cheese-making technology and relationships with the aspect of the cheese curd surface at the moment of its extraction from the cheese vat

Parmigiano Reggiano cheese dairies develop specific cheese-making strategies to adapt the variable characteristics of raw, not standardized milk to the final goal of obtaining cheese consistent with the standard. Analyzing 1,175 cheese-making reports from 30 out of 383 dairies associated with the Parmigiano Reggiano Consortium in 2010 and 2011, 4 groups of Parmigiano Reggiano dairies using specific cheese-making technologies were discriminated by means of multiple linear discriminant analysis. Cheese makers manage cheese-making practices to obtain curd with different roughness properties, classified according to jargon words such as “rigata” and “giusta” or synonyms, because they believe that the roughness of the cheese curd surface immediately after the extraction from the vat is associated with different whey-draining properties and to the final outcome of the cheese. The aspect of the surfaces of the curds produced by the 4 groups of dairies was different according to the technology applied by each group. Cutting of the coagulum when it is still soft for a longer time and faster cooking of the cheese curd grains were associated with a less rough appearance of the surface of the curd, whereas under the opposite conditions, cutting the coagulum when it is firm for a shorter time, led to a curd with a rougher surface. These findings partially support the traditional feeling of Parmigiano Reggiano cheese makers, who consider the curd surface aspect one of the main drivers for their technological choices; to date, however, no data are provided about correlation between the aspect of the curd and the quality of the ripened cheese. If a sufficiently strong correlation could be demonstrated by the future development of the research, the operational effectiveness of Parmigiano Reggiano dairies will be able to largely benefit from the availability of sound and early process markers.     

Effects of cutting intensity and stirring speed on syneresis and curd losses during cheese manufacture

Recombined whole milk was renneted under constant conditions of pH, temperature, and added calcium, and the gel was cut at a constant firmness. The effects of cutting and stirring on syneresis and curd losses to whey were investigated during cheese making using a factorial design with 3 cutting modes designed to provide 3 different cutting intensity levels (i.e., total cutting revolutions), 3 levels of stirring speed, and 3 replications. These cutting intensities and stirring speeds were selected to give a wide range of curd grain sizes and curd shattering, respectively. Both factors affected curd losses, and correct selection of these factors is important in the cheesemaking industry. Decreased cutting intensity and increased stirring speed significantly increased the losses of fines and fat from the curd to the whey. Cutting intensities and stirring speeds in this study did not show significant effects on curd moisture content over the course of syneresis. Levels of total solids, fines, and fat in whey were shown to change significantly during syneresis. It is believed that larger curd particles resulting from low cutting intensities coupled with faster stirring speeds resulted in a higher degree of curd shattering during stirring, which caused significant curd losses.     

Diversity of traditional Caciocavallo cheeses produced in Italy

This paper presents the results of a survey carried out in 68 dairies in southern Italy on the manufacturing processes of traditional Italian Caciocavallo cheese varieties. Following a study of the relevant literature, the various cheesemaking processes were analysed and the implications of different cheesemaking procedures were explored. The manufacturing variations able to influence the organoleptic characteristics of Caciocavallo cheese were milk and rennet types, procedures for curd acidification and stretching, salting and ripening conditions, and smoking treatment. This survey is designed to guide producers and consumers alike with respect to the perceivable effects of manufacturing variants on cheese quality.     

Manipulation of Dhaka cheese curd and effects on cheese quality

Dhaka cheese is a semihard artisanal variety originating from Bangladesh where manual curd kneading is a normal stage in its manufacture. Dhaka cheeses were produced with different degrees of curd kneading to quantify the curd manipulation process in terms of pressure and to standardise the length of operation. The effect of manipulation on the composition, rheology, texture and microstructure of fresh cheese was also studied. Manipulation had significant effects (P < 0.05–0.001) on most of the parameters studied. One minute of curd manipulation was found to be sufficient for Dhaka cheesemaking.     

Cheese yield,cheesemaking efficiency,and daily production of 6 breeds of goats

Little is known about the complex process of cheesemaking at the individual level of dairy goats because of the difficulties of producing a high number of model cheeses. The objectives of this work were (1) to study the cheesemaking ability of goat milk; (2) to investigate the variability of cheesemaking-related traits among different farms; (3) to assess the effects of stage of lactation and parity; and (4) to compare 6 breeds of goat (Saanen and Camosciata delle Alpi for the Alpine type; Murciano-Granadina, Maltese, Sarda and Sarda Primitiva for the Mediterranean type) for their cheesemaking ability. For each goat (n = 560) we studied (1) 8 milk quality traits (fat, protein, total solids, casein, lactose, pH, somatic cell score, and bacterial count); (2) 4 milk nutrient recovery traits (fat, protein, total solids, and energy) in curd; (3) 3 actual cheese yield traits (fresh cheese, cheese solids, and cheese water); (4) 2 theoretical cheese yield values (fresh cheese and cheese solids) and the related cheesemaking efficiencies; and (5) daily milk yield and 3 daily cheese yield traits (fresh cheese, cheese solids, and water retained in the curd). With respect to individual animal factors, farm was not particularly important for recovery traits or actual and theoretical cheese yield and estimates of efficiency, whereas it highly influenced daily productions. Parity of goats influenced daily cheese production, whereas DIM slightly affected recovery as well as percent and daily cheese yield traits. Breed was the most important source of variation for almost all cheesemaking traits. Compared with those of Alpine type, the 4 Mediterranean breeds had, on average, lower daily milk and cheese productions, greater actual and theoretical cheese yield, and higher recovery of nutrients in the curd. Among Alpine type, Camosciata delle Alpi was characterized by greater nutrients recovery than Saanen. Within the 4 Mediterranean types, the 3 Italians produced much less milk per day, with much more fat and protein and greater recovery traits than the Murciano-Granadina, resulting in greater actual cheese yield. Within the Italian breeds, milk from Sarda and Sarda Primitiva was characterized by lower daily yields, higher protein and fat content, and greater recoveries of nutrients than Maltese goats. These results confirmed the potential of goat milk for cheese production and could be useful to give new possibilities and direction in breeding programs.     

Parmigiano Reggiano and Grana Padano cheese curd grains size and distribution by image analysis

Grain sizes (projected area and radius ratio) of 93 Parmigiano Reggiano and Grana Padano cheese curds from four dairies produced using different cutting procedures were measured by bi-dimensional image analysis. Curds were sampled at the end of cutting (fresh curd grains, FCG) and cooking (cooked curd grains, CCG). Mean and median areas of FCG particles were 2.72 and 1.53 mm², respectively. Curd grain shrinkage due to cooking to 54.6 °C ± 0.8 reduced the mean and median area values to 1.63 and 1.09 mm², respectively, with a mean area reduction ratio of 1.76 ± 0.43. Size distribution of the particles was not symmetric and the span value of the distribution of area values of FCG and CCG ranged from 2.6 to 5.8 and from 1.6 to 4.0, respectively. The measuring of cheese curd grains’ size and distribution with a simple method can become a key element to increase the uniformity of curd grains’ size, improving the coagulum cutting operation.     

Galactose concentration in pizza cheese prepared by three different culture techniques

A study was conducted to determine the most suitable lactic culture combinations and the techniques for the preparation of low moisture part skim (LMPS) mozzarella cheese (pizza cheese) with a low level of galactose. The cheesemaking time tested for all 12 culture combinations was less than 3 h and hence was found suitable for pizza cheesemaking. The initial accumulated galactose concentration was lower in unstretched curd followed by no-brine curd and stretched curd in ascending order. During storage of the cheese for 7 days, the galactose percentage in the cheeses prepared using cultures comprising galactose-fermenting strains of Lactobacillus helveticus and Streptococcus thermophilus was 0.30 in stretched curd, 0.04 in unstretched curd and 0.03 in no-brine curd. The degree of reduction in the level of galactose in pizza cheese during storage was maximum with the no-brine curd technique followed by the unstretched and stretched curd techniques in that order. This study provides information regarding selection of starter culture combinations and techniques for pizza cheesemaking based on consumer preference for low or moderate browning mozzarella cheese as a result of its galactose concentration.     

Effects of technological settings on yield,curd, whey,and cheese composition during the cheese-making process from raw sheep milk in small rural dairies: Emphasis on cutting and cooking conditions

The technological conditions of cheese-making affect cheese yield and compound losses in the whey, especially the processes of cutting and cooking. Although significant compositional and functional differences have been reported among animal species, there is a lack of studies on the effects of cheese-making technology on cheese yield and losses for sheep milk. Thus, we examined the cheese-making settings in 8 small rural dairies working with raw sheep milk and their effects on cheese yield and compound losses in whey during the cheese-production season. Actual cheese yield varied in 2 to 3 kg of cheese/100 kg of milk among dairies due to the cheese-making conditions, particularly the duration of cutting and cooking and the final cooking temperature. The combination of the conditions used during cutting and cooking, especially, determined fat losses in the whey. Fat losses were increased with high-speed and short cutting time settings together with high stirring speed and long duration of cooking. Additionally, cheese-makers should adapt the cutting and cooking conditions to the seasonal variations of milk composition, especially during early summer, when fat losses in the whey are higher. Our results suggest that it could be useful to use approximately 10 to 15 min of cutting time and moderate cooking speed and duration. The data reported in this study may assist the improvement of the cheese-making process in small rural dairies using sheep milk, where facilities are limited and the role of the cheese-maker is crucial.     

Response surface methodology modeling of protein concentration,coagulum cut size,and set temperature on curd moisture loss kinetics during curd stirring

The effects of the independent variables protein concentration (4–6%), coagulum cut size (6–18 mm³), and coagulation temperature (28–36°C) on curd moisture loss during in-vat stirring were investigated using response surface methodology. Milk (14 kg) in a cheese vat was rennet coagulated, cut, and stirred as per semihard cheesemaking conditions. During stirring, the moisture content of curd samples was determined every 10 min between 5 and 115 min after cutting. The moisture loss kinetics of curds cut to 6 mm³ followed a logarithmic trend, but the moisture loss of curds from larger cut sizes, 12 or 18 mm³, showed a linear trend. Response surface modeling showed that curd moisture level was positively correlated with cut size and negatively correlated with milk protein level. However, coagulation temperature had a significant negative effect on curd moisture up to 45 min of stirring but not after 55 min (i.e., after cooking). It was shown that curds set at the lower temperature had a slower syneresis rate during the initial stirring compared with curds set at a higher temperature, which could be accelerated by reducing the cut size. This study shows that keeping a fixed cut size at increasing protein concentration decreased the level of curd moisture at a given time during stirring. Therefore, to obtain a uniform curd moisture content at a given stirring time at increasing protein levels, an increased coagulum cut size is required. It was also clear that breakage of the larger curd particles during initial stirring can also significantly influence the curd moisture loss kinetics. Both transmission and scanning electron micrographs of cooked curds (i.e., after 45 min of stirring) showed that the casein micelles were fused at a higher degree in curds coagulated at 36°C compared with 28°C, which confirmed that coagulation temperature causes a marked change in curd microstructure during the earlier stages of stirring. The present study showed the dynamics of curd moisture content during stirring when using protein-concentrated milk at various set temperatures and cut sizes. This provides the basis for achieving a desired curd moisture loss during cheese manufacture using protein-concentrated milk as a means of reducing the effect of seasonal variation in milk for cheesemaking.     

Validation of a curd-syneresis sensor over a range of milk composition and process parameters

An online visible-near-infrared sensor was used to monitor the course of syneresis during cheesemaking with the purpose of validating syneresis indices obtained using partial least squares, with cross-validation across a range of milk fat levels, gel firmness levels at cutting, curd cutting programs, stirring speeds, milk protein levels, and fat:protein ratio levels. Three series of trials were carried out in an 11-L cheese vat using recombined whole milk. Three factorial experimental designs were used, consisting of 1) 3 curd stirring speeds and 3 cutting programs; 2) 3 milk fat levels and 3 gel firmness levels at cutting; and 3) 2 milk protein levels and 3 fat:protein ratio levels, respectively. Milk was clotted under constant conditions in all experiments and the gel was cut according to the respective experimental design. Prediction models for production of whey and whey fat losses were developed in 2 of the experiments and validated in the other experiment. The best models gave standard error of prediction values of 6.6 g/100 g for yield of whey and 0.05 g/100 g for fat in whey, as compared with 4.4 and 0.013 g/100 g, respectively, for the calibration data sets. Robust models developed for predicting yield of whey and whey fat losses using a validation method have potential application in the cheese industry.     

A method for the inline measurement of milk gel firmness using an optical sensor

At present, selection of cutting time during cheesemaking is made based on subjective methods, which has effects on product homogeneity and has prevented complete automation of cheesemaking. In this work, a new method for inline monitoring of curd firmness is presented. The method consisted of developing a model that correlates the backscatter ratio of near infrared light during milk coagulation with the rheological storage modulus. The model was developed through a factorial design with 2 factors: protein concentration (3.4 and 5.1%) and coagulation temperature (30 and 40°C). Each treatment was replicated 3 times; the model was calibrated with the first replicate and validated using the remaining 2 replicates. The coagulation process was simultaneously monitored using an optical sensor and small-amplitude oscillatory rheology. The model was calibrated and successfully validated at the different protein concentrations and coagulation temperatures studied, predicting the evolution of storage modulus during milk coagulation with coefficient of determination values >0.998 and standard error of prediction values <3.4 Pa. The results demonstrated that the proposed method allows inline monitoring of curd firming in cheesemaking and cutting the curd at a proper firmness to each type of cheese.     

Prediction of moisture in cheese of commercial production using neural networks

Control of cheese moisture is paramount to maximizing yield and profitability of a cheesemaking operation. Modeling and prediction of cheese moisture prior to pressing from a large industrial database for stirred-curd Cheddar cheese made with non-standardized and standardized milk was carried out using neural networks (NN). The number of model input variables was reduced by removing or combining some of them, based on cheesemaking knowledge and on the results of two tests estimating the impact of each model input. Input removal was carried out until the validation mean absolute prediction error (MAPE) increased. An initial NN cheese moisture model with 38 input process variables, coded as 57 NN inputs, was reduced to one with 21 input process variables, coded as 34 NN inputs. For the latter, the validation MAPE was 0.53% cheese moisture in a range of cheese moisture of 13.2%, and 0.51% for the best 25% of models (out of 100). For the range of operating conditions of the process in this study, four main groups of variables were found to be the most influential on the prediction of cheese moisture: cutting and subsequent stirring of the curd, curd rinsing temperature, starter quantity, activity and strain, and seasonal variation of milk composition. The NN model with the selected input variables and optimized number of hidden neurons was then used to predict cheese moisture for ranges of these variables. This study showed that NN models can successfully extract input–output variable relationships from industrial production data in spite of the inherent error in these data. The resulting NN models can be used both for research to develop the base of knowledge on production variables and their complex interactions, as well as for the prediction of cheese moisture.     

Computer vision and color measurement techniques for inline monitoring of cheese curd syneresis

Optical characteristics of stirred curd were simultaneously monitored during syneresis in a 10-L cheese vat using computer vision and colorimetric measurements. Curd syneresis kinetic conditions were varied using 2 levels of milk pH (6.0 and 6.5) and 2 agitation speeds (12.1 and 27.2 rpm). Measured optical parameters were compared with gravimetric measurements of syneresis, taken simultaneously. The results showed that computer vision and colorimeter measurements have potential for monitoring syneresis. The 2 different phases, curd and whey, were distinguished by means of color differences. As syneresis progressed, the backscattered light became increasingly yellow in hue for circa 20 min for the higher stirring speed and circa 30 min for the lower stirring speed. Syneresis-related gravimetric measurements of importance to cheese making (e.g., curd moisture content, total solids in whey, and yield of whey) correlated significantly with computer vision and colorimetric measurements.     

High Resolution Magnetic Resonance Imaging Evaluation of Cheese

ABSTRACT: The curd granules/joints structure of the Emmentaler was observed by NMR micro-imaging during the different stages of cheesemaking. During the ripening process, many carbon dioxyde microbubbles have been visualized inside the curd grains, as well as some volumes of fat outside the grains. At the end of the ripening stage, images reveal the final structure does not have a uniform lipid distribution of grains: the density is high at the boundaries and low at the center. Moisture and fat content profile of the rind has been obtained and rind-dependent water and/or fat accumulations are observed. Finally, the contrast difference between curd joints and grains of the studied samples confirms that a higher draining occurs for the joints than for the grains during cheesemaking.     

Microbial diversity of Livanjski cheese with the emphasis on lactic acid bacteria based on culture‐dependent and sequencing method

The microbial diversity of artisanal Livanjski cheese from traditional farms and dairies was analysed. The polyphasic approach included the isolation of microorganisms by using culture‐dependent methods and the identification of viable isolates by sequencing methods. In total, 159 isolates were identified, including five strains of yeast and 15 strains of fungi. Twenty‐two species of homofermentative and heterofermentative lactic acid bacteria were classified. The Shannon–Wiener index of diversity ranged from 0.462 to 2.51 within the cheese samples from the farms and dairies. The hygiene conditions during cheese production and the age of the cheese significantly influenced the counts and diversity of microorganisms.     

Symposium review: The Mozzarella/pasta filata years: A tribute to David M. Barbano

In the decades that followed the end of World War II, Mozzarella cheesemaking in the United States grew steadily as the pizza restaurant established an ever-expanding footprint across America and beyond. By the 1980s, Mozzarella cheesemaking had attained unprecedented scales of production, yet even as new cheese plants were coming on line across the country and production capacities were reaching extraordinary levels, the scientific and technological knowledge base needed to standardize production schedules, control product quality, and maximize cheese yields and efficiency lagged far behind industry needs. It was within this historical context that David Barbano turned his systematic and meticulous research program toward the needs of the Mozzarella cheese industry during the 1980s. By the early 1990s, Barbano was leading a team of graduate students, post-docs, technical staff, and collaborators in a systematic evaluation of every step in the Mozzarella cheesemaking process. The end product of these studies was nothing less than the transformation of what had been (to a large degree) a poorly understood “black box” process into a precisely controlled make procedure that lent itself to precision tailoring of cheese functionality, tight control over manufacturing schedules and efficiency, and maximization of cheese yields. Barbano's international collaborators included research scientists from Italy, where Mozzarella originated. Working with them, Barbano led a systematic evaluation of the scientific and technological aspects of Ragusano cheese, a traditional Protected Designation of Origin pasta filata cheese from Sicily. In the process, Barbano's team demonstrated a new approach to traditional artisanal practices that merged both the art and science of cheesemaking, in effect combining the best of both worlds, toward the goal of sustaining traditional cheesemakers and the working landscapes that they support. Throughout all of these studies, Barbano's research led to innovations in cheesemaking technology (such as improved salting methods, preacidification treatments, and strategies to improve low-fat Mozzarella functionality) that have revolutionized the Mozzarella industry worldwide.     

Effect of homogenization, microfiltration and pH on curd firmness and syneresis of curd grains

The impact of the independent variables, homogenization pressure (p₁), concentration factor of microfiltration (i) and pH on curd firmness (CF) and syneresis of curd grains was studied. Texture analysis was used to characterize CF of the rennet-induced gels. The analysis of a two-level factorial design revealed that i, p₁, pH and the interaction of i and pH had the most important influence on CF. Cutting time was therefore individually determined for each milk system using small amplitude oscillatory rheometry for generating comparable conditions for the syneresis experiments. Syneresis of curd grains with a diameter of 11 mm was followed at 35 °C close to semi-hard cheesemaking conditions. The permeate release during microfiltration was taken into consideration, allowing an evaluation of syneresis of grains made from concentrated and unconcentrated milk. It was shown that with increasing milk concentration less curd treatment time was needed to reach a certain syneresis value. Hence, total processing time in cheesemaking is decreased. Analysis of variance revealed that syneresis was affected by the individual variables. Kinetic parameters were satisfactorily estimated through regression (R²>0.98) and it was shown that milk composition and concentration due to microfiltration markedly influenced the endpoint of syneresis, RWR_max. The experiments demonstrate that microfiltration and homogenization can be combined to reach CF and syneresis comparable to untreated milk used in conventional cheesemaking. This meets one claim of the cheese industry when implementing both technologies in the manufacture process, since consistency and quality of the ripened cheese are expected to be unchanged.