Microstructure Of Cheese Research Articles

The Effect of Using Saline Techniques on the Physicochemical Properties and Microstructure of Laboratory-Made Mozzarella Cheese

This study was conducted in the laboratories of the Food Sciences Department / College of Agriculture / Tikrit University from 1/9/2020 to 1/3/2021. The study included the manufacture of mozzarella cheese from fresh cow’s milk, which were processed by the two salting methods using dry salt and saline ratios. The first method using dry salt with ratios (1, 1.5, 2) g / 100 g of cheese and the second method using brine with concentrations (5, 7.5, 10 %). The effect of the two methods on the physicochemical properties was studied. The results of the physicochemical analysis of mozzarella cheese made from cow's milk showed highest value of pH (5.90) for the control treatment CA and the lowest value ( 5.27 ) for A6 treatment (10% saline solution), as for the bulk total acidity, its values ranged between (0.135_0.173%) for both control CA and A2 (1.5% dry salt) treatments, respectively. The protein percentage recorded the highest value (18.85%) for A5 treatment and the lowest value (15.44%) for A3 treatment, the fat percentage recorded the highest value (18.80%) for A4 treatment and the lowest value (17.14%) for A6 treatment. The results of scanning electron microscopy (SEM) showed the effect of adding salt on improving cheese texture and internal protein composition compared with the control treatment..

New Insights into Cheese Microstructure.

Microscopy is often used to assist the development of cheese products, but manufacturers can benefit from a much broader application of these techniques to assess structure formation during processing and structural changes during storage. Microscopy can be used to benchmark processes, optimize process variables, and identify critical control points for process control. Microscopy can also assist the reverse engineering of desired product properties and help troubleshoot production problems to improve cheese quality. This approach can be extended using quantitative analysis, which enables further comparisons between structural features and functional measures used within industry, such as cheese meltability, shreddability, and stretchability, potentially allowing prediction and control of these properties. This review covers advances in the analysis of cheese microstructure, including new techniques, and outlines how these can be applied to understand and improve cheese manufacture.

The influence of milk protein cross-linking by transglutaminase on technology, composition and quality properties of Gouda-type cheese

The influence of TGase addition simultaneously with rennet on technology, ripening process, sensory properties, texture, microstructure and yield of Gouda-type cheese without inactivation of the enzyme was evaluated. Samples of control (C) and modified (M) Gouda-type cheeses were examined 1 day after brining and after 2, 4 and 6 weeks of ripening. TGase addition resulted in increased coagulation time and formation of a more delicate curd, difficult to process. The enzymatic modification of milk proteins resulted in significantly increased water content in cheese, causing changes in the content of free fatty acids and nitrogen fractions during cheese ripening, and had a negative impact on sensory properties, especially cheese structure, which was crumbly and brittle. Microstructure of ripened M was clearly layered and flaky. TGase modification caused formation of macromolecular protein aggregates. TGase application during production of Gouda-type cheese showed no positive influence on its technology, composition and most quality properties.

Effect of Process and Formulation Variables on the Structural and Physical Properties in Cream Cheese using GDL Acidulant

We report on the properties of analogue cream cheeses prepared using glucono delta-lactone (GDL) acidulant, notably the impact of particular processing and formulation variables, (homogenisation pressure, coagulation pH and temperature, and stabiliser level) on cream cheese physical, material and microstructural properties. Protein–protein and protein-fat interactions were seen to be the primary structural contributors to the physical properties of cream cheese. Cream cheese microstructure and its properties demonstrated well-defined correlations to specific and controllable processing elements within the manufacturing process, showing significance in interactions between parameters in multivariable linear regression analysis (P < 0.05). Summarising the effect of processing variables on key cheese properties, we observed that a progressive reduction in fat particle size of cheese milk arising from increasing homogenisation pressures was seen to increase the total surface area of fat that could be incorporated into the curd during coagulation. The greater extent of fat-fat and fat-proteins interactions during coagulation provided a reinforcing effect on the microstructure of the final cream cheese, with a corresponding increase in compressive fracture stress, shear storage modulus (G′) and shear loss modulus (G″). In terms of other processing variables, cream cheese firmness was also observed to progressively increase through lowering of coagulation pH from 5.13 to 4.33. Increasing coagulation temperature from 58 °C to 78 °C similarly caused an increase in cheese firmness. Finally, increasing the levels of added stabiliser were shown to correlate with increasing cheese firmness. Similar correlations could be observed in relation to physical properties, notably forced expressible serum separation. This model cream cheese preparation method has provided a useful model system for relating food structure to material and functional properties. In addition, it has the advantage of being able to rapidly screen many formulation and process variables because it is faster than the traditional cheesemaking. This study showed that the adjustment of process and formulation variables, either in isolation or in combination, in the manufacture of cream cheese can significantly influence the final material and textural properties of the product, thereby enabling controllable functional attributes capable of meeting different customer needs.

Interaction between phospholipase and transglutaminase in the production of semi-soft fresh cheese and its effect on the yield, composition, microstructure and textural properties

Cheese is considered one of the most important products from milk production worldwide, and its world production has long been growing due to the high and constant demand for dairy products. However, cheese yield has always been a main problematic for cheesemakers from an economic viewpoint because of low values. This research aimed to determine the effect of the type of enzyme and its addition time on the composition, yields, texture, and microstructure of a semi-soft fresh cheese. A multi-factor categorical design was used. Type of enzyme: transglutaminase at 10 g/100L, phospholipase at 6.52 mL/100L, or the interaction between them. And, its time addition were: before, simultaneously or after the addition of rennet. The type of enzyme and its addition time affect statistically the chemical composition of the cheese, yield and texture. Whereas, the addition of transglutaminase together with phospholipase after rennet showed the highest moisture-adjusted yield cheese value (Yma:15.460 g/100L). It is worth noting that an increase of up to 3.89% in the yield was achieved when transglutaminase and phospholipase were used. The addition of transglutaminase together with phospholipase after rennet presented most of the best adjusted yields, suggesting an economical application of the enzyme in cheese making.

Physicochemical, Functional, Fatty Acids Profile, Health Lipid Indices, Microstructure and Sensory Characteristics of Walnut-Processed Cheeses.

In the present study, processed cheeses fortified with walnut paste (a high source of omega-3 fatty acids) were developed and characterized. In order to identify the best cheese formulation, the effects of different proportions of walnut paste (0, 5, 10, and 15%) on cheese physicochemical, functional, fatty acids profile, health lipid indices (atherogenic and thrombogenic), microstructure, and sensorial characteristics were studied. Results showed that walnut-added samples had significantly (p ≤ 0.05) higher levels of acidity, protein, fat, and ash contents with lower meltability and oil separation index compared to the control. Processed cheeses with walnuts contained significantly (p ≤ 0.05) higher percentages of MUFAs, and ω-3 PUFAs (mainly α-linolenic acid) and significantly (p ≤ 0.05) lower amounts of SFAs (mainly myristic, palmitic and stearic acids) and ω6/ω3 ratio. Scanning Electron Micrograph of processed cheese containing walnut paste showed uniform distribution of walnut in the protein matrix. Processed cheeses made with 5 or 10% walnut paste presented the most acceptable sensory properties. These results indicated that walnut paste supplementation can be used as a nutritional strategy to increase concentrations of human health-promoting fatty acids in processed cheeses while maintaining good sensory and technological properties.

Imitation cheese – New insights to relations between microstructure and functionality

The objective of this study was to gain knowledge about the impact of a shift from a protein dominated to a starch dominated continous phase. Furthermore, to determine differences in fat emulsification on the macroscopic behavior of imitation cheese when casein is replaced by chemically modified starch. A novel confocal laser scanning microscopy approach was applied to study the impact of imitation cheese microstructure on melting properties and texture. Using a combination of the dyes FITC, Fast Green, and Nile Blue showed great potential for visualizing structures of complex foods containing both starch, protein, and fat. The macrostructural properties were assessed by textural analysis and rheological temperature sweep and the Schreiber melt test. The hardness and rigidness of imitation cheeses increased with increasing starch concentration. The largest area increase after melting was observed for the imitation cheese with the largest fat droplets. Larger fat droplets indicated reduced fat emulsification. An emulsifying starch decreased the fat droplet size and enabled production of imitation cheese with total casein substitution. This research provides valuable information about the predictors for imitation cheese functionality. The study showed that the melting properties of imitation cheese could be correlated to microstructural stability by determining the fat emulsification.

Changes induced by high hydrostatic pressure in acidified and non‐acidified milk during Oaxaca cheese production

SummaryOaxaca cheese, produced using the pasta filata method, is a very popular Mexican dairy products. In this work, the effect of high hydrostatic pressure (HHP) and the acidification process before and after HHP treatment of raw cow milk was studied at different pressure levels (150, 300 and 500 MPa) and holding times (10 and 30 min). Clotting time, proximal composition, microstructure, secondary protein structure and electrophoretic profile were evaluated. HHP did not influence clotting time in samples acidified before HHP, but it appears to have a positive effect at lower pressure treatments on non‐acidified milk. Moisture, protein and fat were similar in cheeses treated at most HHP conditions regardless of the acidification. HHP did not influence the microstructure of cheese and the secondary structure of proteins. The use of HHP during the manufacture of Oaxaca cheese allowed preserving quality parameters evaluated without advantages in processing time and the product's proximal composition.

Effects of Scalding Temperature, Scalding Time and Ripening Time on the Chemical, Textural and Microstructural Properties of Ovine Milk Urfa Cheese

The objectives of this study were to determine the effect of cheese scalding temperature, scalding time, and ripening time on the chemical, textural and microstructural properties of ovine milk Urfa cheese. Dry salted fresh cheeses were scalded in whey at 70 °C, 80 °C, and 90 °C for 5 and 10 minutes and ripened for 90 days, respectively. Scalding temperature significantly affected fat in dry matter and salt in dry matter (P<0.05), total solids and nitrogen, hardness, cohesiveness, gumminess, and chewiness (P<0.001). Scalding time significantly affected total nitrogen and gumminess (P<0.05), total solids, and hardness (P<0.001). Ripening time significantly affected chemical, textural and color properties of ovine milk Urfa cheese (P<0.001), except fat in dry matter (P<0.05). The color properties of Urfa cheese were not significantly affected by the scalding temperature and time (P>0.05). Besides, scalding treatments have improved the microstructure of ovine milk Urfa cheeses. Urfa cheese exhibited a more compact, coarser, and uniform structure with increasing scalding temperature and time. As a result, scalding treatments and ripening on the chemical, textural and microstructural characteristics of Urfa cheeses were substantially effective.

High Heat Treatment of Goat Cheese Milk. The Effect on Sensory Profile, Consumer Acceptance and Microstructure of Cheese.

Goat cheeses from high heat treated milk (HHTM: 80 °C/5 min (E1) and 90 °C/5 min (E2)), could be regarded as new products, compared to their analogues made from commonly pasteurized milk (65 °C/30 min (C)). Descriptive analysis and consumer tests with a hedonic scale and JAR scale were part of the product development process. The use of scanning electron microscopy enabled deeper insight into the flavor and texture of the cheeses. In all cheese variants, goaty flavor was mildly pronounced. Young HHTM cheeses also had a pronounced whey and cooked/milky flavor. Consumers found such flavor ‘too intensive’. Unlike the control variant, HHTM cheeses were not described as ‘too hard’. Such improvement in texture was found to be a result of fine, highly branched microstructure, sustained over the course of ripening time and highly incorporated milk fat globules inside the cheese mass. Cluster analysis showed that the largest group of consumers (47.5%) preferred E2 cheese. Although consumers found that most of the cheeses were ‘too salty’, this excess did not decrease their overall acceptance. Neither microstructure analysis nor descriptive sensory analysis of goat white brined cheeses produced from high heat treated milk has been done before.

Cream cheese made with exopolysaccharide-producing Lactococcus lactis: Impact of strain and curd homogenization pressure on texture and syneresis

This study examined texture, syneresis and microstructure of cream cheese manufactured at curd homogenization pressures of 0.05, 15 or 30 MPa and with three Lactococcus lactis strains differing largely in type and molecular characteristics of their exopolysaccharides (EPS). Cream cheese with non-ropy EPS showed higher firmness and serum retention after curd homogenization at higher pressure, but also larger particles. The presence of ropy EPS, however, resulted in higher yield stress and creaminess, and capsular EPS presumably to higher serum retention of cheese after curd homogenization at 0.05 and 15 MPa. Applying 30 MPa had an opposed effect probably due to lower shear resistance of the ropy and capsular EPS. The cluster analysis revealed two groups of EPS-pressure combinations (0.05/15 MPa for ropy and capsular EPS; 15/30 MPa for non-ropy EPS) which resulted in cream cheese with high firmness and serum retention, and are therefore suggested for application at industrial level.

Study of the “Pokrovskiy” cheese microstructure at various degrees of maturity before drying, after freeze drying and after vacuum drying

The article presents studies of the “Pokrovskiy” cheesemicrostructure at various stages of ripening; cheesesampleswere taken at each stage of ripening and were dried by freeze-drying and vacuum drying, and then were subjected to microstructure studies. By micrographs of the cheese “Pokrovskiy”after vacuum and freeze drying, it was found that the cheese has a cellular structure from the first days of ripening. Drying the cheese allowed performing a more detailed study of thecheese structure. After drying, a cellular structure of the cheese was revealed.

Study of the microstructure of stained cheeses

A selection of methods for cheese mass coloring was performed. Cheeses stained with Sudan III according to Herxheimer’s method have fat of a bright orange color, and on micrographs this fat is clearly distinguished in the form of droplets with a diameter of 30 to 100 microns. Moreover, the fatty droplets in the micrographs, regardless of the cheese type, are predominantly light in color (white). The microstructure of cheeses stained with Sudan III and Methylene Blue has a cellular structure. Their fat droplets in micrographs have a dark color (gray or black). The size of the fat droplets is the same as that of cheeses stained with Sudan III according to Herxheimer’s method, from 30 to 100 microns.

Changes in the cheese “pokrovskiy” microstructure during the ripening process

Issues of cheese microstructure in relation to the determination of its quality characteristics at various stages of the ripening process are of considerable interest. For the correct performance of the production process, it is important to get knowledge about the changes in the capillary structure of the curd mass in the process of cheese ripening and further storage. As a result of the conducted research, it was established when, in the process of ripening, a pattern begins to appear in the Pokrovskiy cheese. It was studied how the size of fat droplets changes during its maturation. The size of the cheese microcapillaries was determined. The dynamics of changes in the elemental composition of thecheesePokrovskiy in the process of its maturation has been investigated. The location of calcium phosphate in the curd mass at different stages of ripening is determined. The possibility of its identification using a scanning electron microscope has been proven.

Effects of shredding on the functionality, microstructure and proteolysis of low-moisture mozzarella cheese

Low-moisture mozzarella cheese (LMMC) is commonly shredded before packaging, however, the effects of shredding are not fully understood. Industrially-produced block and shredded LMMC were studied during 8 weeks of storage at 4 °C. Cheese shredded on 15 d and at 8 weeks of age, coated with microcrystalline cellulose and stored in a modified atmosphere (70% N2 and 30% CO2), had an altered microstructure after 8 weeks compared with vacuum-packed block cheese. In the latter case the fat formed a more dispersed phase. Proteolysis was higher in shredded samples and a higher level of two bacterial proteases was detected. Despite these differences, the meltability and stretchability of the block and shredded LMMC were similar. The microstructure and functionality of cheese shredded at 15 d and stored for a further 6 weeks was similar to cheese shredded at 8 weeks, suggesting there is a flexible period for performing cheese shredding processes.

Effect of the manufacturing process on Fiore Sardo PDO cheese microstructure by multi-frequency NMR relaxometry

The quality of Fiore Sardo cheese, a traditional Italian dairy product, was analyzed by means of Multi-frequency Nuclear Magnetic (NMR) relaxometry. Specifically, ten cheese wheels were purchased from different production chains, either industrial (N = 5) or artisanal (N = 5) samples. The former came from large scale productions and the latter were produced by shepherds in small quantities and in very small dairy factories. A preliminary interlaboratory proficiency testing of Time Domain - NMR (TD-NMR, 20 MHz) relaxometry by five laboratories, consistently showed that product quality is significantly different in terms of molecular mobility according to their production chain (i.e. industrial or artisanal). More detailed information about cheese microstructure was obtained by Multi-frequency Fast Field Cycling NMR (FFC-NMR) at lower magnetic fields (0.01–10 MHz). According to the interpretative model adopted to describe FFC-NMR data, industrially processed cheeses showed a higher para-casein hydration, higher protein protons to water protons ratio and a higher disorder (lower fractal dimension df) than artisanal products. It is suggested that differences between artisanal and industrial cheeses generate from the processing steps preceding cheese maturation, and are clearly reflected in the visual appearance of cheeses.This study shows that NMR relaxometry techniques can successfully discriminate Fiore Sardo cheese from different production chains, and paves the way for their implementation in quality control practices of dairy products.

FATTY ACID COMPOSITION AND MICROSTRUCTURE OF RIPENED GOAT CHEESE

The aim of this study was to evaluate the changes in the fatty acid composition and microstructure of goat cheeses during 80 days of ripening. Creole goat milk from the Quebrada de Humahuaca was used to produce cheeses. Samples were taken 5 hours and 10, 20, 30, 40, 60 and 80 days after preparation. The composition of fatty acids for each period was determined by gas chromatography. The changes in the matrix cheese were observed using an electron microscopy. The medium-chain fatty acids and the unsaturated fatty acids decreased during the whole study but at two different velocities. They became established at the end of the ripening time, which is coincident with the decrease in fatty globule sizes: 2–4.6 µm at the beginning, 300 ηm at 30 days of ripening, and 140 ηm at the end of the maturation time studied.

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.

Technical note: Repeatability and reproducibility of curd yield and composition in a miniaturized coagulation model

Miniaturized coagulation (MC) models have been proposed for the evaluation of curd yield (CY) in individual milk samples of different dairy species and breeds, and for the analysis of cheese microstructure and texture. It is still unclear if MC using less than 50 mL of milk is suitable to evaluate CY and chemical composition, and if preservative added to raw milk may interfere with MC process. Therefore, this study aimed at evaluating repeatability and reproducibility of CY, curd moisture, and fat and protein content on curd dry matter (DM) from MC trials using 40 g of milk. Miniaturized coagulations were performed by 3 different operators on 3 consecutive days, using raw milk (RM) and raw milk added with preservative (RMP). Repeatability of CY, calculated as relative standard deviation on 6 miniaturized curds obtained within a day by the same operator, was below 5% for MC carried out with both RM and RMP. The Horwitz ratio, which is the ratio between measured and expected reproducibility, highlighted good reproducibility for CY from RM and fair reproducibility for CY from RMP. The same ratio highlighted lower accuracies for curd moisture and fat and protein content on curd DM, especially for MC trials carried out with RMP. The z-test was performed to evaluate the similarity between curds manufactured with RM and RMP in terms of average yield and chemical composition; z-scores did not highlight significant differences between values obtained from MC carried out with RM and RMP. It can be concluded that preservative had negligible effects on MC, giving the opportunity to extend milk physical and chemical stability, to schedule laboratory trials on longer time span, and to broaden the sample size within a batch of analyses.

Improving quark-type cheese yield and quality by treating semi-skimmed cow milk with microbial transglutaminase

This work aimed at studying the impact of adding different concentrations of microbial transglutaminase (MTGase) during the making process of quark, a mainly acid coagulated fresh cheese, using re-heated semi-skimmed milk. The results indicated that cheese yield increased linearly with increasing enzyme concentrations, thus reaching values of up to 19% higher than those of control cheeses. This increase resulted from reducing losses during the cheese-making process, both uncontrolled and at the curd-cutting step; all enzyme-assisted treatments exhibited similar behaviours and consequently, similar recovered protein levels. Yield differences among enzymatic treatments were due to changes in the amount of retained water related to variations in the MTGase-promoted protein polymerization level and their effects on cheese microstructure. Moreover, MTGase increased cheese hardness by strengthening protein network, and enhanced the nutritional quality due to the higher protein content; however, in both cases, an enzyme overdose involved a setback in the improvements obtained.