Search

ABSTRACT: Residual lipids (RL) in whey protein isolate (WPI) are detrimental to optimal functional applications (e.g., foaming and low turbidity) and contribute to off-flavor development during powder storage. The objective of this research was to prepare an experimental WPI by removing RL without using the traditional microfiltration process and compare its properties with commercially available WPI made using microfiltration and some other whey powders. We hypothesize that by adjusting the pH of whey to

ABSTRACT: Due to its versatility and shelf stability, process cheese is gaining interest in many developing countries. The main structural component (base) of most processed cheese formulations is young Cheddar cheese that has high levels of intact casein. Exporting natural Cheddar cheese base from the United States to distant overseas markets would require the aging process to be slowed or reduced. As Cheddar cheese ripens, the original structure is broken down by proteolysis and solubilization of insoluble calcium phosphate. We explored the effect of varying rennet levels (we also used a less proteolytic rennet) and application of high-pressure processing (HPP) to Cheddar cheese, as we hoped these treatments might limit proteolysis and concomitant loss of intact casein. To try to retain high levels of insoluble Ca, all experimental cheeses were made with a high-draining pH and from concentrated milk. To compare our intact casein results with current practices, we manufactured a Cheddar cheese that was prepared according to typical industry methods (i.e., use of unconcentrated milk, calf chymosin [higher levels], and low draining pH value [∼6.2]). All experimental cheeses were made from ultrafiltered milk with protein and casein contents of ∼5.15% and 4.30%, respectively. Three (low) rennet levels were used: control (38 international milk clotting units/mL of rennet per 250 kg of milk), and 25% and 50% reduced from this level. All experimental cheeses had similar moisture contents (∼37%) and total Ca levels. Four days after cheese was made, half of the experimental samples from each vat underwent HPP at 600 MPa for 3 min. Cheddar cheese functionality was monitored during aging for 240 d at 4°C. Cheddar cheese base was used to prepare process cheese after aging for 14, 60, 120, 180, and 240 d. Loss tangent (LT) values of cheese during heating were measured by small strain oscillatory rheology. Intact casein levels were measured using the Kjeldahl method. Acid or base titrations were used to determine the buffering capacity and insoluble Ca levels as a percentage of total Ca. The LTmax values (an index of meltability) in process cheese increased with aging for all the cheese bases; the HPP treatment significantly decreased LTmax values of both base (natural) and process cheeses. All experimental cheeses had much higher levels of intact casein compared with typical industry-make samples. Process cheese made from the experimental treatments had visually higher stretching properties than process cheese made from Cheddar with the typical industry-make procedure. Residual rennet activity was not affected by rennet level, but the rate of proteolysis was slightly slower with lower rennet levels. The HPP treatment of Cheddar cheese reduced residual rennet activity and decreased the reduction of intact casein levels. The HPP treatment of Cheddar cheese resulted in process cheeses that had slightly higher hardness values, lower LTmax values, and retained higher storage modulus values at 70°C. We also observed that the other make procedures we used in all experimental treatments (i.e., using a less proteolytic chymosin, using a concentrated cheese milk, and maintaining a high draining pH value) had a major effect on retaining high levels of intact casein.

ABSTRACT: Bifidobacterium animalis ssp. lactis ATCC27536 and Lactobacillus acidophilus ATCC4356 were encapsulated in a conjugated whey protein hydrolysate (WPH10) through spray drying. Probiotic cultures were added at the ratio of 1:1 into the conjugated WPH10 solution at a spiking level of about 10 log10 cfu/mL. The mixture was spray dried in a Niro drier with inlet and outlet temperatures of 200°C and 90°C, respectively. The final dried product was determined for cell viability and further stored for 16 wk at 25°, 4°, and −18°C to monitor viability and functionality. Micro images showed the presence of link bridges in non-conjugated WPH10, whereas, in the case of conjugated WPH10, round particles with pores were observed. The mean probiotic counts before and after spray drying were 10.59 log10 cfu/mL and 8.98 log10 cfu/g, respectively, indicating good retention of viability after spray drying. The solubility and wetting time of the WPH10-maltodextrin (MD) encapsulated probiotic powder were 91.03% and 47 min, whereas for WPH10, the solubility and wetting time were 82.03% and 53 min, respectively. At the end of storage period, the counts were 7.18 log10 cfu/g at 4°C and 7.87 log10 cfu/g at −18°C, whereas at 25°C the counts were significantly reduced, to 3.97 log10 cfu/g. The solubility of WPH-MD powder was 82.36%, 83.1%, and 81.19% at −18°C, 4°C, and 25°C, respectively, and wetting times were 61 min, 60 min, and 63 min at −18°C, 4°C, and 25°C, respectively. By contrast, for WPH10 powder, the solubility significantly reduced to 69.41%, 69.97%, and 68.99% at −18°C, 4°C, and 25°C, and wetting times increased to 71 min, 70 min, and 72 min at −18°C, 4°C, and 25°C, respectively. The conjugated WPH10 is thus demonstrated as a promising carrier for probiotics and can be further used as an ingredient for developing functional foods, to harness their enhanced functionality and health benefits derived from both WPH and probiotics.

Some European dairies use low concentration factor microfiltration (MF) in their cheese plants. Removal of whey protein (WP) from milk before cheesemaking using microfiltration without concentration provides the opportunity to produce a value-added by-product, milk-derived whey. However, few studies have focused on the effects on cheese properties caused by the depletion of WP from cheese milk. Most studies have concentrated cheese milk using MF in addition to depletion of WP. In our approach, cheese milk was not concentrated during WP depletion using MF. We wanted to quantify residual WP levels in cheese made from MF milk and to explore whether WP depletion from milk would influence functionality, nutritional profile, and cheese quality during ripening. Casein (CN) contents for all milks were kept at ∼2.5%, to eliminate the confounding factor of concentration of CN, which was observed in some previous MF studies. Cheese milks had similar ratios of CN to fat. Three standardized milks were produced with various CN:true protein (TP) ratios: (a) control with a CN:TP ratio of 83:100, (b) 35% WP depletion, 89:100 CN:TP, and (c) 70% WP depletion, 95:100 CN:TP. Cheddar cheeses were made from MF milk with various WP depletion levels and aged for 9 mo, and their functionality was evaluated during ripening. We found no major differences in cheese composition or pH values between samples. Cheese yield, solids recovery, and nitrogen recovery were slightly higher in the 95:100 CN:TP cheeses compared with the control. These enhanced recoveries reflect that MF-treated milk started with a higher fraction of CN-based protein solids, rather than WP solids. The standardized milk from the 95:100 CN:TP treatment also had a slightly higher fat content compared with the control, likely helping to increase cheese yield. Rheological properties of cheeses during heating were similar between treatments. Hardness initially decreased with age for all cheeses due to proteolysis or solubilization, or both, of calcium phosphate. Maximum loss tangent (LT), an index of cheese meltability, was slightly lower for the control cheese until 30 d of ripening, but after 30 d, all treatments exhibited similar maximum LT values. The temperature where LT = 1 (crossover temperature), an index of softening point during heating, was slightly lower for MF cheese compared with the control cheeses during ripening. Microfiltration treatment had no significant influence on proteolysis. Sensory properties were similar between the cheeses, except for bitterness. Bitterness intensity was slightly lower in the MF cheeses than in the control cheeses and increased in all cheeses during ripening. We detected no major differences in the concentrations of key nutrients or vitamins between the various cheeses. Depletion of WP in cheese milk by MF did not negatively affect cheese quality, or its nutritional profile, and resulted in similar cheesemaking yields. [ABSTRACT FROM AUTHOR]

Milk protein concentrate (MPC) powders (~81% protein) were made from skim milk that was heat treated at 72°C for 15 s (LHMPC) or 85°C for 30 s (MHMPC). The MPC powder was manufactured by ultrafiltration and diafiltration of skim milk at 50°C followed by spray drying. The MPC dispersions (4.02% true protein) were prepared by reconstituting the LHMPC and MHMPC powders in distilled water (LHMPCw and MHMPCw, respectively) or milk permeate (LHMPCp and MHMPCp, respectively). Increasing milk heat treatment increased the level of whey protein denaturation (from ~5 to 47% of total whey protein) and reduced the concentrations of serum protein, serum calcium, and ionic calcium. These changes were paralleled by impaired rennet-induced coagulability of the MHMPCw and MHMPCp dispersions and a reduction in the pH of maximum heat stability of MHMPCp from pH 6.9 to 6.8. For both the LHMPC and MHMPC dispersions, the use of permeate instead of water enhanced ethanol stability at pH 6.6 to 7.0, impaired rennet gelation, and changed the heat coagulation time and pH profile from type A to type B. Increasing the severity of milk heat treatment during MPC manufacture and the use of permeate instead of water led to significant reductions in the viscosity of stirred yogurt prepared by starter-induced acidification of the MPC dispersions. The current study clearly highlights how the functionality of protein dispersions prepared by reconstitution of high-protein MPC powders may be modulated by the heat treatment of the skim milk during manufacture of the MPC and the composition of the solvent used for reconstitution. [ABSTRACT FROM AUTHOR]

Traditionally most protein ingredients are sold as a powder due to transport ease and longer shelf life. Many high-protein powder ingredients such as milk protein concentrate with 85% protein and micellar casein concentrate have poor rehydration properties (e.g., solubility) after storage, which might limit their use. An alternative to the production of dried protein ingredients is the option to use liquid protein ingredients, which saves the cost of spray drying, but may also improve flavor and offer different functional properties. The objective of this study was to determine the effect of spray drying on the flavor and functionality of high-protein ingredients. Liquid and dried protein ingredients (whey protein concentrate with 80% protein, whey protein isolate, milk protein concentrate with 85% protein, and micellar casein concentrate) were manufactured from the same lot of milk at the North Carolina State University pilot plant. Functional differences were evaluated by measurement of foam stability and heat stability. Heat stability was evaluated by heating at 90°C for 0, 10, 20, and 30 min followed by micro-bicinchoninic acid and turbidity loss measurements. Sensory properties were evaluated by descriptive analysis, and volatile compounds were evaluated by gas chromatography-mass spectrometry. No differences were detected in protein heat stability between liquids and powders when spray dried under these conditions. Whey protein concentrate with 80% protein (liquid or spray dried) did not produce a foam. All powders had higher aroma intensity and cooked flavors compared with liquids. Powder proteins also had low but distinct cardboard flavor concurrent with higher relative abundance of volatile aldehydes compared with liquids. An understanding of how spray drying affects both flavor and functionality may help food processors better use the ingredients they have available to them. [ABSTRACT FROM AUTHOR]

Understanding the chemistry of milk and its components is critical to the production of consistent, highquality dairy products as well as the development of new dairy ingredients. Over the past 100 yr we have gone from believing that milk has only 3 protein fractions to identifying all the major and minor types of milk proteins as well as discovering that they have genetic variants. The structure and physical properties of most of the milk proteins have been extensively studied. The structure of the casein micelle has been the subject of many studies, and the initial views on submicelles have given way to the current model of the micelle as being assembled as a result of the concerted action of several types of interactions (including hydrophobic and the formation of calcium phosphate nanoclusters). The benefits of this improved knowledge of the type and nature of casein interactions include better control of the cheesemaking process, more functional milk powders, development of new products such as cream liqueurs, and expanded food applications. Increasing knowledge of proteins and minerals was paralleled by developments in the analysis of milk fat and its synthesis together with greater knowledge of its packaging in the milk fat globule membrane. Advances in analytical techniques have been essential to the isolation and characterization of milk components. Milk testing has progressed from gross compositional analyses of the fat and total solids content to the rapid analysis of milk for a wide range of components for various purposes, such as diagnostic issues related to animal health. Up to the 1950s, research on dairy chemistry was mostly focused on topics such as protein fractionation, heat stability, acid–base buffering, freezing point, and the nature of the calcium phosphate present in milk. Between the 1950s and 1970s, there was a major focus on identifying all the main protein types, their sequences, variants, association behavior, and other physical properties. During the 1970s and 1980s, one of the major emphases in dairy research was on protein functionality and fractionation processes. The negative cloud over dairy fat has lifted recently due to multiple reviews and meta-analyses showing no association with chronic issues such as cardiovascular disease, but changing consumer misconceptions will take time. More recently, there has been a great deal of interest in the biological and nutritional components in milk and how these materials were uniquely designed by the cow to achieve this type of purpose. [ABSTRACT FROM AUTHOR]

The residual annatto colorant in fluid Cheddar cheese whey is bleached to provide a neutral-colored final product. Currently, hydrogen peroxide (HP) and benzoyl peroxide are used for bleaching liquid whey. However, previous studies have shown that chemical bleaching causes off-flavor formation, mainly due to lipid oxidation and protein degradation. The objective of this study was to evaluate the efficacy of microfiltration (MF) on norbixin removal and to compare flavor and functionality of 80% whey protein concentrate (WPC80) from MF whey to WPC80 from whey bleached with HP or lactoperoxidase (LP). Cheddar cheese whey was manufactured from colored, pasteurized milk. The fluid whey was pasteurized and fat separated. Liquid whey was subjected to 4 different treatments: control (no bleaching; 50°C, 1 h), HP (250 mg of HP/kg; 50°C, 1 h), and LP (20 mg of HP/kg; 50°C, 1 h), or MF (microfiltration; 50°C, 1 h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% concentrate. The entire experiment was replicated 3 times. Proximate analyses, color, functionality, descriptive sensory and instrumental volatile analysis were conducted on WPC80. The MF and HP- and LP-bleached WPC80 displayed a 39.5, 40.9, and 92.8% norbixin decrease, respectively. The HP and LP WPC80 had higher cardboard flavors and distinct cabbage flavor compared with the unbleached and MF WPC80. Volatile compound results were consistent with sensory results. The HP and LP WPC80 were higher in lipid oxidation compounds (especially heptanal, hexanal, pentanal, 1-hexen-3-one, 2-pentylfuran, and octanal) compared with unbleached and MF WPC80. All WPC80 had >85% solubility across the pH range of 3 to 7. The microstructure of MF gels determined by confocal laser scanning showed an increased protein particle size in the gel network. MF WPC80 also had larger storage modulus values, indicating higher gel firmness. Based on bleaching efficacy comparable to chemical bleaching with HP, flavor, and functionality results, MF is a viable alternative to chemical or enzymatic bleaching of fluid whey. [ABSTRACT FROM AUTHOR]

High sodium intake negatively affects consumer health, thus there is active interest in lowering sodium levels in dairy foods. Cheddar and low-moisture, part-skim Mozzarella cheeses were made with total salt levels of 0.7, 1.0, 1.25, 1.35, and 1.8% (wt/wt) in triplicate, thus reducing sodium by 25 to 60%. Multiple manufacturing protocols for salt reduction were used to produce cheeses with similar postpress moisture and pH, independent of the final salt levels in cheese, in order to study the role of salt in cheese acceptability. Cheese flavor was evaluated by a descriptive taste panel on a 15-point intensity scale. Consumer acceptance was evaluated by a consumer panel on a 9-point hedonic scale. Taste panels conducted with cubed Cheddar cheese (at 3 and 6 mo) and cold shredded Mozzarella cheese (at 3 wk) showed that consumer liking for cheese was low at 0.7 and 0.9% salt, but all cheeses containing higher salt levels (1.25, 1.35, and 1.8% salt) were comparably preferred. The cheeses had acceptable liking scores (≥6) when served as quesadilla or pizza toppings, and consumers were able to differentiate cheeses at alternate salt levels; for example, 1.8 and 1.5% salt cheeses scored similarly, as did cheeses with 1.5% and 1.35% salt, but 1.35% salt cheese scored lower than and was discernible from 1.8% salt cheese. Descriptive panelists perceived salty, sour, umami, bitter, brothy, lactone/fatty acid, and sulfur attributes as different across Mozzarella cheeses, with the perception of each significantly increasing along with salt level. Salty and buttery attributes were perceived more with increasing salt levels of Cheddar cheese by the descriptive panel at 3 mo, whereas bitter, brothy, and umami attributes were perceived less at the higher salt levels. However, this trend reversed at 6 mo, when perception of salty, sour, bitter, buttery, lactone/fatty acid, and umami attributes increased with salt level. We conclude that consumers can distinguish even a 30% salt reduction and a gradually phased sodium reduction is needed to improve acceptability of lower sodium cheeses. [ABSTRACT FROM AUTHOR]

The manufacture of Queso Fresco (QF), a highmoisture fresh Mexican cheese that is popular in the Americas, varies from country to country, with many manufacturers milling the curd before forming the cheese block to disrupt the protein matrix and ensure the crumbly nature of the QF. Because this traditional milling step does take time and may be an unnecessary point of microbial contamination, this study was undertaken to determine whether the curd-milling step could be omitted without altering the chemical, functional, and textural properties of the QF. Starter culture-free, rennet-set QF was prepared from pasteurized, homogenized milk. Curds were cooked at 39°C for 30 min, wet salted at 1.45 g of NaCl/100 g of milk, chilled, and divided into 4 portions. Curds were not milled or were subjected to coarse, medium, or fine milling and handpacked into molds. After 12 h at 4°C, the cheese was divided, vacuum packaged, and stored at 4°C for up to 8 wk. Fresh QF contained 57.3 ± 1.2% moisture, 20.9 ± 0.8% fat, 16.0 ± 1.3% protein, 2.61 ± 0.15% lactose, and 2.25 ± 0.22% salt and had a pH of 6.36 ± 0.03%. Moisture decreased over the 8 wk of storage, whereas the fat level tended to increase. All cheeses lost 1.3 to 1.7% of their weight in whey during the first week after manufacture, and the weight gradually increased to 2.1% (nonmilled) to 3.2% (milled) by wk 8. Milling did result in QF that were softer, less chewy, and less rigid and with lower viscoelastic properties than nonmilled cheeses. Sensory panelists differentiate the finely milled QF from the other treatments, but they detected no significant differences among the nonmilled, coarsely milled, and medium-milled QF. Milling of the curd did not affect the ability of Listeria monocytogenes to grow on the cheese surface. Results from this study indicate that the milling step, which lengthens the manufacturing time, does increase wheying off during storage and results in a more fragile protein matrix. Cheese manufacturers can use this information to produce a QF that meets the demands of their customers [ABSTRACT FROM AUTHOR]

Understanding filtration mechanisms at a molecular level is important for predicting structural and functional properties of globular milk proteins after membrane operations. This stage is thus highly decisive for the further development of membrane separations as an efficient alternative to chromatographic processes for the fractionation of milk proteins. In this study, we proposed an original and complete analytical package for the examination of the putative effect of filtration at both macroscopic and molecular levels. We then investigated the pertinence of this analytical package during ultrafiltration (UF) of globular milk proteins in both dead-end and crossflow modes. Reverse-phase HPLC combined with statistical computing was shown to be relevant for the assessment of even slight physically induced modifications. Adaptations of circular dichroism and solubility measurements, regarding their respective dependence on temperature and pH, were also useful for an accurate evaluation of functional modifications. At last, immunochemistry was proven to be a pertinent tool for the specific detection of modifications affecting a targeted protein, even in mixed solutions. Moreover, results obtained by such methods were shown to be coherent with data obtained from classical techniques such as fluorescence. For β-lactoglobulin, some physically induced modifications were noticed in the permeate because of shear stress inside membrane pores. In the case of α-lactalbumin dead-end UF, permeation was shown to affect protein characteristics because of an increase in the relative calcium content responsible for a conformational transition from the apo-form to the holo-form of the protein. Finally, during crossflow UF with limited transmission of BSA, observations were coherent with a partial aggregation because of the circulation of proteins in the filtration pilot. Such a hypothesis corroborates results previously mentioned in the literature. [ABSTRACT FROM AUTHOR]

The functionality of whey proteins can be modified by many approaches; for example, via complexation with carbohydrates, enzymatic cross-linking, or hydrolysis, and the objective of this work was to research the effects of supercritical carbon dioxide (scCO2) treatments on the functionalities of commercial whey protein products including whey protein isolates (WPI) and whey protein concentrates (WPC). The WPI and WPC powders and a 10% (wt/vol) WPI solution were treated with scCO2. The WPI solution was treated at 40°C and 10 MPa for 1 h, whereas WPI and WPC powders were treated with scCO2 at 65°C and 10 or 30 MPa for 1 h. Dynamic rheological tests were used to characterize gelation properties before and after processing. Compared with the unprocessed samples and samples processed with N2 under similar conditions, scCQ-treated WPI, whether dispersed in water or in the powder form during treatments, formed a gel with increased strength. The improvement in gelling properties was more significant for the scCO2-treated WPC. In addition, the scCO2-processed WPI and WPC powders appeared to be fine and free-flowing, in contrast to the clumps in the unprocessed samples. Proximate compositional and surface hydrophobicity analyses indicated that both compositional and structural changes may have contributed to enhanced whey protein functionalities. The results suggest that functionalities of whey proteins can be improved by scCO2 treatment to produce novel ingredients. [ABSTRACT FROM AUTHOR]

Pizza cheese was manufactured with milk (12.1% total solids, 3.1% casein, 3.1% fat) standardized with microfiltered (MF) and diafiltered retentates. Polymeric, spiral-wound MF membranes were used to process cold (<7°C) skim milk, and diafiltration of MF retentates resulted in at least 36% removal of serum protein on a true protein basis. Cheese milks were obtained by blending the MF retentate (16.4% total solids, 11.0% casein, 0.4% fat) with whole milk (12.1% total solids, 2.4% casein, 3.4% fat). Control cheese was made with part-skim milk (10.9% total solids, 2.4% casein, 2.4% fat). Initial trials with MF standardized milk resulted in cheese with approximately 2 to 3% lower moisture (45%) than control cheese (~47 to 48%). Cheese-making procedures (cutting conditions) were then altered to obtain a similar moisture content in all cheeses by using a lower setting temperature, increasing the curd size, and lowering the wash water temperature during manufacture of the MF cheeses. Two types of MF standardized cheeses were produced, one with preacidification of milk to pH 6.4 (pH6.4MF) and another made from milk preacidified to pH 6.3 (pH6.3MF). Cheese functionality was assessed by dynamic low-amplitude oscillatory rheology, University of Wisconsin MeltProfiler, and performance on pizza. Nitrogen recoveries were significantly higher in MF standardized cheeses. Fat recoveries were higher in the pH6.3MF cheese than the control or pH6.4MF cheese. Moisture-adjusted cheese yield was significantly higher in the 2 MF-fortified cheeses compared with the control cheese. Maximum loss tangent (LTmax) values were not significantly different among the 3 cheeses, suggesting that these cheeses had similar meltability. The LTmax values increased during ripening. The temperature at which the LTmax was observed was highest in control cheese and was lower in the pH6.3MF cheese than in the pH6.4MF cheese. The temperature of the LTmax decreased with age for all 3 cheeses. Values of 12% trichloroacetic acid soluble nitrogen levels were similar in all cheeses. Performance on pizza was similar for all cheeses. The use of MF retentates derived with polymeric membranes was successful in increasing cheese yield, and cheese quality was similar in the control and MF standardized cheeses. [ABSTRACT FROM AUTHOR]

In a previous study, exopolysaccharide (EPS)-producing cultures improved textural and functional properties of reduced fat Cheddar cheese. Because base cheese has an impact on the characteristics of process cheese, we hypothesized that the use of EPS-producing cultures in making base reduced fat Cheddar cheese (BRFCC) would allow utilization of more young cheeses in making reduced fat process cheese. The objective of this study was to evaluate characteristics of reduced fat process cheese made from young BRFCC containing EPS as compared with those in cheese made from a 50/50 blend of young and aged EPS-negative cheeses. Reduced fat process cheeses were manufactured using young (2 d) or 1-mo-old EPS-positive or negative BRFCC. Moisture and fat of reduced fat process cheese were standardized to 49 and 21%, respectively. Enzyme modified cheese was incorporated to provide flavor of aged cheese. Exopolysaccharide-positive reduced fat process cheese was softer, less chewy and gummy, and exhibited lower viscoelastic moduli than the EPS-negative cheeses. The hardness, chewiness, and viscoelastic moduli were lower in reduced fat process cheeses made from 1-mo-old BRFCC than in the corresponding cheeses made from 2-d-old BRFCC. This could be because of more extensive proteolysis and lower pH in the former cheeses. Sensory scores for texture of EPS-positive reduced fat process cheeses were higher than those of the EPS-negative cheeses. Panelists did not detect differences in flavor between cheeses made with enzyme modified cheese and aged cheese. No correlations were found between the physical and melting properties of base cheese and process cheese. [ABSTRACT FROM AUTHOR]

The objective of this research was to use a Rapid Visco Analyzer to study the effect of natural cheese age, trisodium citrate (TSC) concentration, and mixing speed on process cheese food (PCF) functionality. In this study 3 replicates of natural cheese were manufactured, and a portion of each cheese was subjected to 6 different PCF manufacturing treatments at 2, 4, 6, 12, and 18 wk of ripening. These treatments were factorial combinations of 3 levels of TSC (i.e., 2.0, 2.5, and 3.0%) and 2 mixing speeds during manufacture (450 and 1,050 rpm). Functional properties of the PCF evaluated included manufacturing properties [apparent viscosity after manufacture (VAM)], unmelted textural properties (firmness), melted cheese flow properties [hot apparent viscosity (HAV)], and cheese thickening during cooling [time at 5000 cP (T5)]. All 4 parameters (VAM, firmness, HAV, and T5) were significantly affected by natural cheese age and mixing speed, whereas VAM, HAV, and T5 were also significantly influenced by the amount of TSC. The VAM and firmness decreased as cheese age increased, whereas T5 values increased as cheese age increased. Similarly, VAM, HAV, and firmness values increased because of the increased mixing speed, whereas T5 values decreased. The age x mixing speed interaction was significant tbr VAM and firmness. The age x concentration of the TSC interaction term was significant for VAM, whereas the age x age x TSC concentration term was significant for HAV. The results demonstrate that natural cheese age, mixing speed during manufacture, and concentration of TSC have a significant impact on process cheese functionality [ABSTRACT FROM AUTHOR]

Compositional changes in raw and pasteurized cream and unconcentrated sweet cream buttermilk (SCB) obtained from a local dairy were investigated over 1 yr. Total phospholipid (PL) composition in SCB ranged from 0.113 to 0.153%. Whey protein denaturation in pasteurized cream over 1 yr ranged from 18 to 59%. Pizza cheese was manufactured from milk standardized with condensed SCB (∼34.0% total solids, 9.0% casein, 17.8% lactose). Effects of using condensed SCB on composition, yield, PL recovery, and functional properties of pizza cheese were investigated. Cheesemilks were prepared by adding 0, 2, 4, and 6% (wt/wt) condensed SCB to part-skim milk, and cream was added to obtain cheesemilks with ∼11.2 to 12.7% total solids and casein:fat ratio of ∼1. Use of condensed SCB resulted in a significant increase in cheese moisture. Cheese-making procedures were modified to obtain similar cheese moisture contents. Fat and nitrogen recoveries in SCB cheeses were slightly lower and higher, respectively, than in control cheeses. Phospholipid recovery in cheeses was below 40%. Values of pH and 12% trichloroacetic acid-soluble nitrogen were similar among all treatments. Cheeses made from milk standardized with SCB showed less melt and stretch than control cheese, especially at the 4 and 6% SCB levels. Addition of SCB significantly lowered free oil at wk 1 but there were no significant differences at wk 2 and 4. Use of SCB did not result in oxidized flavor in unmelted cheeses. At low levels (e.g., 2% SCB), addition of condensed SCB improved cheese yield without affecting compositional, rheological, and sensory properties of cheese. [ABSTRACT FROM AUTHOR]

Effects of 2 types of emulsifying salts (ES) on the functionality of nonfat pasta filata cheese were examined. Nonfat pasta filata cheese was made from skim milk by direct acidification. Trisodium citrate (TSC) and tetrasodium pyrophosphate (TSPP) were added to curds (at 1, 3, and 5%, wt/wt) at the dry-salting step, together with glucono-δ-lactone to maintain a constant pH. When TSC was added, there were no significant compositional differences, although insoluble Ca and P contents significantly decreased with the addition of TSC. When TSPP was added, fat content was not significantly different, but protein content decreased with increasing concentrations of TSPP. Both insoluble Ca and P contents increased with the addition of 1% TSPP. The addition of ES affected textural and functional properties. With increasing concentrations of TSC, meltability increased, whereas increasing the TSPP content decreased meltability. Cheese made with 1% TSC had better stretchability compared with control cheese. However, the addition of more than 3% TSC decreased stretchability. Addition of TSPP caused a considerable decrease in stretchabilty. Scanning electron microscopy revealed that the size and number of serum pockets decreased and protein appeared more hydrated with the addition of both ES. These results suggested that TSC and TSPP influenced the functionality of nonfat pasta filata cheese differently; that is, the effects of TSC were probably caused by a decrease in the number of colloidal calcium phosphate cross-links and an increase in electrostatic repulsion, whereas the effects of TSPP may have been related to the formation of new TSPP-induced casein-casein interactions. [ABSTRACT FROM AUTHOR]

Whey, a byproduct of the cheesemaking process, is concentrated by processors to make whey protein concentrates (WPC) and isolates (WPI). Only 50% of whey proteins are used in foods. In order to increase their usage, texturizing WPC, WPI, and whey albumin is proposed to create ingredients with new functionality. Extrusion processing texturizes globular proteins by shearing and stretching them into aligned or entangled fibrous bundles. In this study, WPC, WPI, and whey albumin were extruded in a twin screw extruder at approximately 38% moisture content (15.2 ml/min, feed rate 25 g/min) and, at different extrusion cook temperatures, at the same temperature for the last four zones before the die (35, 50, 75, and 100°C, respectively). Protein solubility, gelation, foaming, and digestibility were determined in extrudates. Degree of extrusion-induced insolubility (denaturation) or texturization, determined by lack of solubility at pH 7 for WPI, increased from 30 to 60, 85, and 95% for the four temperature conditions 35, 50, 75, and 100°C, respectively. Gel strength of extruded isolates increased initially 115% (35°C) and 145% (50°C), but gel strength was lost at 75 and 100°C. Denaturation at these melt temperatures had minimal effect on foaming and digestibility. Varying extrusion cook temperature allowed a new controlled rate of denaturation, indicating that a texturized ingredient with a predetermined functionality based on degree of denaturation can be created. [ABSTRACT FROM AUTHOR]

Presents abstracts of several studies on the chemistry of dairy foods. "Utilization of Front Face Flourescence Spectroscopy for Rapid Analysis of Process Cheese Functionality," by S. K. Garimella Purna, L. A. Prow and L. E. Metzger; "Rapid Impedance Method to Detect Adulterated Milk," by D. L. Marshall and G. M. Duran; "Characterization of Flavor and Flavor Compounds in Dried Whey Protein Concentrates and Isolates," by M. Carunchia Whetstine; "The Influence of Non-Fat-Dairy Milk Characteristics on Yogurt Functionality," by A. Pollard and L. E. Metzger.