Cheese Yield Research Articles

Composition, coagulation characteristics, and cheese making capacity of yak milk

Yak is one of the few species of which the rennet-coagulated cheese making characteristics of its milk are still not well understood. This study investigated composition and rennet-induced coagulation properties of milk from 17 individual yak cows in comparison with milk from 32 individual Holstein cows. Yak cows produced milk with generally higher concentrations of milk components. The concentrations of fat, protein, solids-not-fat (SNF), and calcium in yak milk were 1.89-, 1.68-, 1.46-, and 2-fold those in Holstein milk, respectively. The hydrodynamic radii of casein micelles (187.25 nm) and chymosin-induced paracasein (1,620 nm) were about twice the sizes of those found in Holstein milk. Higher concentrations of calcium in yak milk, together with larger sizes of casein micelles, explains the reason for its fast rate of curd formation and firmer curd texture. Optical microrheology analysis also showed that Ca2+ concentration had greater influence on the coagulation of yak milk than on Holstein milk. Cheese making trials with yak and Holstein milk proved the higher cheese yield of yak milk: 1.67-fold that of Holstein milk. Therefore, yak milk could be a suitable source of milk for enzyme-coagulated cheese making.

Goat cheese yield and recovery of fat, protein, and total solids in curd are affected by milk coagulation properties

The aims of the present research were to quantify the effects of each coagulation trait, traditional milk coagulation properties [MCP: rennet coagulation time (RCT), curd-firming time (k20), and curd firmness at 30 min (a30)], and modeled curd-firming over time (CFt) parameters [estimated rennet coagulation time (RCTeq), curd-firming instant rate constant (kCF), and potential curd firmness (CFP)] directly on the following: (1) recovery of 3 milk components in the curd (%REC), (2) 3 measures of cheese yield (%CY), and (3) 3 daily cheese yield traits (dCY) from goat milk. Cheese-making traits were analyzed using 2 mixed different models, the first to test MCP and the second to test CFt parameters. Pearson correlations were also calculated. Significant and favorable relationships (negative for time intervals and positive for CF measures) were found between the traditional MCP and the CFt parameters and %REC and %CY traits. The effects of milk fat and protein contents were particularly important on all cheese-making traits, with the only exception being the effect of fat content on water retention in cheese (%CYWATER). We found an optimum value of milk k20, associated with the highest recovery of components and cheese yield in solids (%CYSOLIDS). In addition, a lower level of curd water retention and an increased fresh curd yield (%CYCURD) were associated with greater recovery of fat. The collection of all available information during the process of milk coagulation and curd-firming allowed us to discover the effect of RCTeq on %REC traits and %CYSOLIDS, which had not previously been revealed for traditional RCT. Moreover, higher kCF values were associated with increased %CYCURD and %CYSOLIDS. Given that CFt parameters showed a high level of independence from one another, these can also be easily used and characterized in future applications at the industry level. Information provided by traditional and modeled coagulation properties could efficiently support the goat dairy industry and lay the foundations for a quality payment scheme for goat milk.

Chemical composition and sensory properties of soy-tiger nut cheese

Soy-cheese was produced from blends of soymilk and tiger nut milk at varying proportions of 100:0, 95:5, 90:10, 85:5, 80:20 and 75:25 respectively. The proximate, mineral and sensory properties of the cheese samples were evaluated. Cheese yield and protein content significantly reduced with increase in tiger nut milk addition. The protein content of the soy-tiger nut cheese blends decreased from 19.04% to 13.25%, while fat contents increased from 7% to 9.14%. Calcium (126.42-189.80 mg/kg) and potassium (145.27-194.33 mg/kg) are the major minerals in the cheese samples, while the iron content was substantially low (11.03-14.67 mg/kg). Phytate and trypsin inhibitor contents of the cheese samples significantly reduced with increasing levels of tiger-nut, suggesting improvement in digestibility. Cheese produced from 95% soy milk and 5% tiger-nut milk had the highest rating in all sensory parameters. This study demonstrated the possibility of utilizing blends of soymilk and tiger-nut milk in cheese production with comparable nutritional and sensory quality to the common 100% soy cheese. Furthermore, producing soy-cheese from soymilk and tiger nut milk blend may be a promising means of value addition to further promote utilisation of tiger-nut milk beyond traditional usage.

Research of heat treatment influence of milk on quality and safety of hard cheeses

The object of research is raw milk used for the production of hard cheeses by milk processing enterprises of Ukraine. The quality of raw milk is especially important, a key factor determining the effectiveness of the milk processing industry. Without milk, which meets certain requirements, it is impossible to organize the production of high-quality products. Special requirements are placed on the quality of raw milk intended for the cheese production. One of the most problematic places is improving the quality and cheese suitability of raw milk and improving the technological process for the production of natural hard cheesesDuring the study, laboratory (biochemical and microbiological) research methods are used to determine the quality indicators of raw milk and finished products, as well as their microbial contamination. And for processing the results of the study, methods of mathematical statistics are used.The work shows that bacterial contamination of raw milk, which exceeds the normative limit values, poses a threat to both the technological process of cheese making and the quality of the finished product. Methods are proposed for preventing a decrease in the yield of cheese and deterioration in its quality due to prolonged storage of milk at low temperatures. It is proved that the best results are obtained with ultra-high-temperature processing of milk with an exposure of 2–4 s. And also, that high-temperature and, especially, ultra-high-temperature (UHT treatment) is a very effective way to destroy bacterial microflora and improve the quality of raw milk by such an indicator as a «pollution tank». This allows to increase the cheese ability of raw milk. High temperatures of heat treatment of milk lead to changes in the salt and protein composition of milk. These changes should have both negative consequences – a deterioration in the rennet coagulation of milk and the synergistic properties of the clot, and a positive result consisting in an increase in the transfer of milk solids, primarily whey proteins, to clot and cheese.

Studying the effect of electrospark treatment of milk whey on the process of its fermentation and quality of thermoacid cheese

The paper reports a study into the influence of electrospark dispersion of current-conductive granules of magnesium and manganese in the environment of milk whey on the process of its fermentation in the technology of making soft thermo-acid cheeses the type of Adyheyskyy.The object of this study was milk whey, obtained from the thermo-acid settling of cheeses. To prepare the coagulant, it was treated in an electric discharge chamber with a current-conductive layer of magnesium or/and manganese granules manganese over 30...120 s.It has been established that the result of such a treatment of milk whey is the increased magnesium content, by 1.8 to 4 times on average, and the increased manganese content, by 1.5 to 3.8 times on average, depending on the treatment duration.It has been proven that it was characteristic, of all the examined samples, to demonstrate a natural growth of titrated acidity during fermentation. However, the samples enriched with mineral elements following the electrospark treatment over 30...60 s have shown a more intensive growth in titrated acidity. Similar results were obtained when using milk whey from cottage cheese. Although at the initial stages of fermentation (0...6 hours) the increase in acidity was somewhat slower, which has an objective explanation related to the effect of enhanced acidity of the starting whey (50...60 °T) on lactobacilli.It was established that the production cycle is significantly reduced in case of using the proposed technology of acidic whey-coagulant for making thermo-acid cheeses.There is also an increase in the utilization coefficient of technological equipment and its resources. A given technology does not require significant areas for the introduction of an innovative electro-physical technique, and, instead, given the reduced fermentation time, it contributes to reducing the number of containers involved in the preparation of coagulant.It has been established that the use of acidic whey, produced from raw materials enriched with magnesium and manganese, in the technology of thermo-acid cheese contributes to its enrichment with valuable mineral elements. It also provides for a more complete use of the protein potential of milk and, consequently, increases the thermo-acid cheese yield by 1.8...6.5 %

Efficiency assessment of water reclamation processes in milk protein concentrate manufacturing plants: A predictive analysis

Milk protein concentrates (MPC) are increasingly used as protein fortifiers in food formulations, as a means to increase cheese yield, and in the manufacture of Greek-style yogurt. However, manufacturing of MPC requires significant volumes of input water and generates polluting by-products such as permeates and/or diafiltrates. Reverse osmosis was suggested to reduce the impact of both issues by reclaiming water from dairy fluids, thereby reducing the volumes of by-products to be treated. Filtration performance data was obtained from the reverse osmosis of dairy fluids, namely skim milk and ultrafiltration permeate, and from the polishing process of their respective permeates. It allowed the comparison of various water reclamation scenarios through a predictive analysis, which revealed that, without increasing operational costs, preconcentrating the skim milk prior the MPC manufacture would reduce the use of water and electricity by 35% and 10%, respectively, compared to a traditional process that consists in the concentration of skim milk by ultrafiltration, followed by the concentration of the resulting retentate by reverse osmosis.

Nutritional composition and consumer acceptability of cheese analog from soy and cashew nut milk

Promoting the utilization of locally available protein-rich crops may reduce the problem of protein-energy malnutrition. The physicochemical properties and consumer acceptance of soybean and cashew nut milk cheese analog were evaluated. Vegan milk blends were prepared by substituting soy milk with cashew nut milk at different proportions of 0%, 20%, 40%, 60%, 80%, and 100%. The color coordinates showed no significant differences among the samples. The percentage vegan cheese yield decreased by increasing the level of substitution. The vegan cheese analog produced with 40% cashew nut milk had the highest protein and ash but was lower in lipid. The overall acceptability of the samples decreased with increasing cashew nut milk substitution. However, sample blend with 40% cashew nut milk was preferred in terms of flavor, color, and overall acceptability. Vegan cheese analog from cashew nut and soy milk blends could be a promising value-added product serving as an alternative protein source. Practical applications This study showed that an acceptable vegan cheese analog could be produced from the blends of soy and cashew nut milk. This cheese analog could serve as a vegetable protein source with the potential of reducing the incidence of protein-energy malnutrition. It could also serve as a rich source of essential fatty acids.

Effect of Nutrition on flaxseed Supplementation to Lactating Goats on Physiochemical and Nutritional Properties of Domiati Cheese in Halayeb, Shalateen and Abu Ramad Triangle of Egypt

The purpose of this research was to evaluate the effect of feeding lactating goats with flaxseed on the physicochemical, sensory properties, yield, texture and fatty acids profile of Domiati cheese. Goat's milk resulted from goat feed different flaxseed levels (0, 7 and 14%) were used in the preparation of goat's Domiati cheese which was stored at 4±1oC for 60 days. Results showed that supplementing flaxseed at level 7and 14% had significantly (P< 0.05) increased cheese protein, total solids and lactose, while no effect was observed on cheese fat. Cheese yield was significantly increased (P< 0.5) for cheese supplemented with 7 and 14%flaxseed than control cheese. Results also, showed in significant differences (P<0.05) on short- (SCFA) and medium-chain fatty acids (MCFA) .While a significant increase of mono -unsaturated (MUFA) and poly-unsaturated fatty acids (PUFA) in cheese fat were observed. Moreover, concentrations of conjugated linoleic acid (CLA) isomers and linolenic acid (C18:3) in cheese fat were increased linearly (P < 0.05) with the increase of flaxseed level. The concentration of CLA and C18:3 in cheese with7 and 14 % flaxseed concentrates significant (P< 0.05) increased. It was concluded that feeding flaxseed to lactating goats improved fatty acids profile in cheese as well as cheese yield. The texture profile parameters were significant (P< 0.05) decreased. Sensory properties scores were increased during storage period. Generally, resultant goat's Domiati cheese supplemented with 7 and 14% flaxseed were considered highly acceptable and it has many health benefits than the control cheese.

Low-temperature centrifugation of milk for manufacture of raw milk cheeses: Impact on milk debacterization and cheese yield

Centrifugation is occasionally applied to clean cheese milk, particularly to remove Clostridia's spores that may cause the “late blowing” of cheese. The sludge separated by centrifugation also contains fat and protein, thus is sterilized and added back to cheese milk. In manufacture of raw milk cheeses, centrifugation shall be performed at temperature below 40 °C and no sterilized sludge can be added to vat milk. Both these limitations negatively affect cheese yield. To evaluate process sustainability, three different centrifugation configurations were tested at a factory producing a traditional raw-milk extra-hard cheese. Either a single or double centrifugation, the latter with two different volumes of discharged sludge, were tested over 3-week periods each. Efficiency of spore removal, decrease of total bacterial count, loss of milk solids and cheese yield were evaluated daily with respect to not-centrifuged milk from the same batch. Double centrifugation with low-volume sludge gave highest efficiency of spore removal, i.e. 98.2%, while the single process minimized the loss of cheese yield. Impedometric analysis indicated that centrifugation caused a preferential removal of rod-shaped lactic acid bacteria, regardless of configuration. This finding was confirmed by microscopy and suggested that a different bacteria population would operate during cheese ripening.

Understanding the differences in cheese-making properties between reverse osmosis and ultrafiltration concentrates

Concentrating milk by reverse osmosis (RO) has the potential to increase cheese yield but is known to impair cheese-making properties. The main compositional differences between ultrafiltration (UF) and RO concentrates are the high lactose and mineral contents of the latter. The objective of this work was to determine the distinct effects of high lactose and high minerals on the cheese-making properties of RO concentrate, by supplementing UF concentrate with lactose. The soluble colloidal equilibria of concentrates were studied as well as several other properties: rennet gelation behavior, cheese mass balance, composition, and microstructure. Rennet coagulation time was longer and gel firming rate was lower for RO concentrate than for UF concentrate. Lactose was mainly responsible for these differences. Lactose in RO concentrate was also responsible for the 7% increase of moisture-adjusted cheese yield, relative to UF concentrate. Compared with cheese made from UF concentrate, cheese made from RO concentrate showed higher moisture content, which could not be attributed to lactose but to the high mineral concentration. This study showed the potential of using RO instead of UF concentrate to maximize cheese yield. The approach is, however, limited to applications where post-acidification can be controlled, and will require appropriate strategies to reduce the negative effects of high mineral content in RO concentrate.

Biochemical characteristics of reduced-fat cheese made from high-heat treated goat’s milk supplemented with Penicillium candidum

Novel reduced-fat goat-cheese (R) was produced from high-pasteurized milk using Penicillium candidum as an adjunct. A full-fat goat-cheese (F) from pasteurized milk without mold addition was produced for comparison reasons. Physicochemical analyses of the two cheeses were performed through the 14-d period of ripening. The effect of P.candidum on proteolysis of goat-cheese caseins and the production of hydrophilic and hydrophobic peptides during cheese ripening were investigated. To our knowledge, similar results for reduced-fat, mold-ripened, goat-milk cheeses have not been previously reported before. R-cheese exhibited a higher organoleptic score and developed properties similar to Kopanisti, which is a Protected Designation of Origin Greek soft cheese with specific intense flavour manufactured from raw milk without the use of starters. Moreover, R-cheese had significantly higher moisture, protein in dry matter and water soluble nitrogen contents than F-cheese and was less adhesive. The high-pasteurization improved the texture and cheese yield, while the use of P. candidum as an adjunct improved the flavour, increased and accelerated proteolysis in R-cheese. According to the results, the technology for R-cheese employed in the present study can be easily adopted and could be used to produce a reduced-fat goat-cheese.

Production of cheese from donkey milk as influenced by addition of transglutaminase

Donkey milk is characterized by low contents of total solids, fat, and caseins, especially κ-casein, which results in formation of a very weak gel upon renneting. The objective of this study was to evaluate the effect of fortification of donkey milk with microbial transglutaminase (MTGase) for cheesemaking in relation to different enzyme addition protocols (patterns, PAT). Four independent trials were performed using MTGase (5.0 U/g of milk protein) according to the following experimental patterns: control (no MTGase addition); MTGase addition (40°C) 15 min before starter inoculation (PAT1); addition of MTGase to milk simultaneously with starter culture (40°C) (PAT2); and MTGase addition simultaneously with rennet (42°C) in acidified milk (pH 6.3) (PAT3). Evolution of pH during acidification, cheesemaking parameters, and proximal composition and color of cheese at 24 h were recorded. The protein fractions of cheese and whey were investigated by urea-PAGE and sodium dodecyl sulfate-PAGE. Addition of MTGase had no significant effect on moisture, protein, fat, or cheese yield. The addition of MTGase with rennet (PAT3) improved curd firmness compared with the control. Among the different patterns of MTGase addition, PAT3 reduced gel formation time, time between rennet addition and cheese molding, and weight loss of cheese at 24 h. The PAT3 treatment also resulted in the lowest lightness and highest yellowness color values of the cheese. Sodium dodecyl sulfate-PAGE of cheeses revealed that MTGase modified the protein pattern in the high-molecular-weight zone (range 37-75 kDa) compared with the control. Of the MTGase protocols, PAT3 showed better casein retention in cheese, as confirmed by the lanes of α- and β-caseins in the electropherogram of the whey, which was subtler for this protocol. In conclusion, MTGase may be used in cheese production from donkey milk to improve curd firmness; MTGase should be added simultaneously with the rennet.

Improvement of Oxidative Status, Milk and Cheese Production, and Food Sustainability Indexes by Addition of Durum Wheat Bran to Dairy Cows’ Diet

Simple SummaryIn the near future, the expected increase in world population will enhance feed versus food competition between animals and humans to face the increasing demand by humans. For this reason, it is of paramount importance to feed ruminants with sources alternative to those representing themselves foods for humans. Durum wheat bran (DWB), similar to other by-products of the agri-food industry, can meet this need, its fiber content is high and represents also a remarkable source of phenolic acids, especially ferulic acid. This compound exerts antioxidant properties improving the health status of animals, and allows the production of functional foods more and more requested by consumers. Accordingly, this experiment demonstrated the suitability of using DWB for dairy cows feeding, because it led to clear advantages in terms of oxidative status of animals, quality of dairy products, and feeding costs. Furthermore, DWB improved the human-edible feed conversion efficiency reducing the use of human-edible feed.Durum wheat bran (DWB) is a by-product mostly used in feeding ruminants, contributing to decrease in the utilization of feeds suitable as foods for human consumption, thus improving the sustainability of livestock production. However, the potential benefits of DWB, due to its content in phenolic acids, mainly consisting of ferulic acid with antioxidant properties, have not been well clarified yet. Accordingly, in this experiment, 36 lactating cows divided into three groups received, over a period of 100 days, one of three concentrates including DWB at 0% (DWB0), 10% (DWB10), or 20% (DWB20). The concentrates were formulated to be isoproteic and isoenergetic and, to balance the higher fiber content of the concentrates with DWB, the hay in the diets was slightly reduced. During the trial, the group feed intake and the individual milk production were monitored, and cheese was made with bulk milk from each group. Milk yield and microbiological characteristics of milk and cheese were similar among groups, indicating no DWB effect on cows performance and fermentation process. Milk from DWB20 group resulted slightly higher in casein and curd firmness (a2r). In cows fed DWB, the higher polyphenol intake was responsible for higher blood contents of these bioactive compounds, that seemed to have contributed in reducing the level of reactive oxygen metabolites (ROMs), which were higher in DWB0 cows. DWB20 cheeses showed a higher polyphenol content, lower number of peroxides, and higher antioxidant capacity than DWB0 cheeses. DWB20 and DWB10 diets resulted less expensive. In addition, the DWB20 group showed the best indexes heFCE (human edible feed conversion efficiency = milk/human edible feed) and NFP (net food production = milk − human edible food), expressed as crude protein or gross energy. In conclusion, the DWB fed to dairy cows at 12% of diet dry matter (DM) can lead to benefits, such as the improvement of oxidative status of cows, milk quality, shelf-life, and functional properties of cheese, and might contribute to reduce the feeding cost and limit the human-animal competition for feeding sources.

Prediction of Milk Coagulation Properties and Individual Cheese Yield in Sheep Using Partial Least Squares Regression

Simple SummaryConsidered that all sheep milk in Italy is destined for cheese processing, traits describing rennet coagulation aptitude should be among the most important selection goals for dairy breeds. To reduce the costs and logistics related to the large-scale recording of these traits, mid-infrared (MIR) spectroscopy could be conveniently used to generate reliable predictions without any additional cost. The aims of this research were to predict the milk coagulation properties (MCP) and individual cheese yield (ILCY) in sheep by MIR spectrometry using partial least squares regression (PLS), and to compare different data pre-treatment procedures. The prediction results observed in the present study, although moderate, suggest the possibility of adding novel phenotypes (e.g., MCP and ILCY) in breeding schemes for dairy sheep breeds. Mid-infrared spectroscopy coupled with PLS regression could allow the prediction of phenotypes at the population level without additional costs.The objectives of this study were (i) the prediction of sheep milk coagulation properties (MCP) and individual laboratory cheese yield (ILCY) from mid-infrared (MIR) spectra by using partial least squares (PLS) regression, and (ii) the comparison of different data pre-treatments on prediction accuracy. Individual milk samples of 970 Sarda breed ewes were analyzed for rennet coagulation time (RCT), curd-firming time (k20), and curd firmness (a30) using the Formagraph instrument; ILCY was measured by micro-manufacturing assays. An Furier-transform Infrared (FTIR) milk-analyzer was used for the estimation of the milk gross composition and the recording of MIR spectrum. The dataset (n = 859, after the exclusion of 111 noncoagulating samples) was divided into two sub-datasets: the data of 700 ewes were used to estimate prediction model parameters, and the data of 159 ewes were used to validate the model. Four prediction scenarios were compared in the validation, differing for the use of whole or reduced MIR spectrum and the use of raw or corrected data (locally weighted scatterplot smoothing). PLS prediction statistics were moderate. The use of the reduced MIR spectrum yielded the best results for the considered traits, whereas the data correction improved the prediction ability only when the whole MIR spectrum was used. In conclusion, PLS achieves good accuracy of prediction, in particular for ILCY and RCT, and it may enable increasing the number of traits to be included in breeding programs for dairy sheep without additional costs and logistics.

Rheological and microstructural properties of rennet gel made from caprine milk treated by HP

Caprine milk has poor rheological properties, which usually result in low cheese yield, as well as economic loss to cheesemakers. Several methods had been used to improve its coagulation properties. However, high pressure (HP) had been rarely used. With the aim of improving the milk coagulation properties, this study therefore assessed the effects of HP treatment on caprine milk before rennet-induced coagulation. Additionally, the rheological, textural, microstructural characteristics and water-holding capacity of the curds were evaluated as a function of pressure (300, 400 and 500 MPa), holding time (20, 40 and 60 min), and temperature (20, 40 and 60 °C) using a response surface methodology. The Box-Behnken design was used to investigate the effect of process variables. The results showed that with an increase in pressure level or holding time, or a decrease in temperature, the rennet coagulation time showed a decreasing trend while curd firming rate and coagulum strength showed the opposite. Also, an increased pressure level, temperature and time resulted in an increase in water-holding capacity and a subsequent decrease in the gel-firmness of the curds. The trend of the results was confirmed by Scanning electron micrographs of the curds. HP could therefore be an alternative technology for improving the coagulation properties of caprine milk.

Coagulation Traits of Sheep and Goat Milk.

Simple SummaryThe suitability of milk for cheese production is usually predicted at dairy plants using mathematical formulas, which are based on milk protein and fat content. In addition, several methods, which use a small volume of milk to simulate the cheesemaking processes and stages, are currently available at the laboratory level. Those methods have been developed and improved for cow milk. In the present review, the author reports the available literature and current methods to analyze coagulation traits from sheep and goat milk.Milk production from sheep and goat species is continuously growing worldwide, and its main use is for cheesemaking. Given that the final quality of cheese is linked to the traits of raw milk cheese yield at dairy plants, it is often calculated by using predictive formulas based on fat and protein content. Predictive formulas have been studied for bovine milk and are very effective but not appropriate for sheep and goat milk. Several methods, which simulate the actual coagulation processes, are available at the laboratories. This article reviews the available literature about rennet coagulation and cheese yield traits from sheep and goat milk and the methods used at the laboratory level. In general, if compared to cow milk, sheep and goat milk are characterized by shorter rennet coagulation times and a very limited amount of non-coagulating samples. Curd firmness of sheep milk is almost independent from the rennet coagulation time, and some coagulation traits can be predicted by infrared spectra. In addition, coagulation traits are characterized by appropriate values of heritability to be considered in selective breeding plans. With regard to goat milk, rennet coagulation time and cheese yield are strongly influenced by the breed effect.

Phenotypic and genetic parameter estimates of cheese-making traits and their relationships with milk production, composition and functional traits in Spanish Assaf sheep

Sheep milk is mostly used for the production of cheese. In this study, a commercial population of Spanish Assaf sheep was analyzed for six cheese-making traits: four related to milk-coagulation properties (MCPs) [rennet coagulation time (RCT), curd-firming time (K20), and curd firmness at minutes 30 and 60 (A30, A60)] and two related to cheese yield [individual laboratory cheese yield (ILCY) individual laboratory dried curd yield (ILDCY)]. Records for milk production traits were also available for this study. Restricted maximum likelihood (REML) analysis was used to estimate the genetic parameters and variance components, whereas bivariate models were used to calculate the phenotypic and genetic correlations among the traits considered in this work. Of the 1,143 milk samples included in the study, 147 (13%) did not coagulate, whereas 425 samples (approximately 37%) showed slow coagulation (samples with a record for A60 and a missing record for A30). Also, large mean values were observed for RCT (29.54 min) and logK20 (1.35 min). The heritabilities estimated for the cheese-making traits were moderate, ranging between 0.15 (for ILDCY) and 0.30 (A30 and ILCY). In general, within the pairs of related cheese-making traits, we found moderate-high phenotypic and genetic correlations. The RCT and logK20 traits showed high negative correlations with A30 and A60 at both the genetic and phenotypic levels. From the estimation of genetic parameters among these and several milk traits, the high and positive genetic correlations observed between PP and the two cheese yield traits should be highlighted. Based on the estimated phenotypic correlations, our study supports that subclinical mastitis is related to a delayed gelification of milk and lower curd firmness. Overall, this study provides the first report about the phenotypic and genetic parameters of cheese-making traits in a commercial population of Assaf sheep, offering preliminary information that might help to identify the cheese-making or related milk production traits that could be considered to improve Assaf population toward enhanced cheese performance features.

Effects of indirect indicators of udder health on nutrient recovery and cheese yield traits in goat milk

In dairy goats, very little is known about the effect of the 2 most important indirect indicators of udder health [somatic cell count (SCC) and total bacterial count (TBC)] on milk composition and cheese yield, and no information is available regarding the effects of lactose levels, pH, and NaCl content on the recovery of nutrients in the curd, cheese yield traits, and daily cheese yields. Because large differences exist among dairy species, conclusions from the most studied species (i.e., bovine) cannot be drawn for all types of dairy-producing animals. The aims of this study were to quantify, using milk samples from 560 dairy goats, the contemporary effects of a pool of udder health indirect indicators (lactose level, pH, SCC, TBC, and NaCl content) on the recovery of nutrients in the curd (%REC), cheese yield (%CY), and daily cheese yields (dCY). Cheese-making traits were analyzed using a mixed model, with parity, days in milk (DIM), lactose level, pH, SCC, TBC, and NaCl content as fixed effects, and farm, breed, glass tube, and animal as random effects. Results indicated that high levels of milk lactose were associated with reduced total solids recovery in the curd and lower cheese yields, because of the lower milk fat and protein contents in samples rich in lactose. Higher pH correlated with higher recovery of nutrients in the curd and higher cheese yield traits. These results may be explained by the positive correlation between pH and milk fat, protein, and casein in goat milk. High SCC were associated with higher recovery of solids and energy in the curd but lower recovery of protein. The higher cheese yield obtained from milk with high SCC was due to both increased recovery of lactose in the curd and water retention. Bacterial count proved to be the least important factor affecting cheese-making traits, but it decreased daily cheese yields, suggesting that, even if below the legal limits, TBC should be considered in order to monitor flock management and avoid economic losses. The effect of NaCl content on milk composition was linked with lower recovery of all nutrients in the curd during cheese-making. In addition, high milk NaCl content led to reductions in fresh cheese yield and cheese solids. The indirect indicators of the present study significantly affected the cheese-making process. Such information should be considered, to adjust the milk-to-cheese economic value and the milk payment system.

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.

Evaluation of Aflatoxin M1 Enrichment Factor in Semihard Cow's Milk Cheese and Correlation with Cheese Yield

The aflatoxin M1 content in milk was not related to the enrichment factor. The enrichment factor in 45-day ripened semihard cheese was defined. The enrichment factor in cheese is affected by cheese yield.