Chemical Pretreatment and Microfiltration for Making Delipidized Whey Protein Concentrate

Chemical pretreatment, microfiltration (MF) and ultrafiltration (UF) were applied to produce delipidized whey protein concentrates (WPC). Processes including both chemical pretreatment and MF resulted in WPC with <0.5% lipids. Low-pH UF and isoelectric point (PI) precipitation were more effective for lipid removal than chemical pretreatment by thermocalcic aggregation. Protein permeation ratios in MF processes were improved by UF preconcentration of whey. Protein permeation and flux were different between the two MF membranes used. Isoelectric point precipitation increased β-Lg contents, but not α-La, in the resulting WPC (B). Minor proteins exhibited lower concentrations in WPC B and MF WPC products.     

Effect of Whey Pretreatment on Composition and Functional Properties of Whey Protein Concentrate

The effect of pretreatment upon the composition and physicochemical and functional properties of whey, ultrafiltration (UF) retentate and freeze-dried and spray-dried whey protein concentrates (WPC) was investigated. Pretreatment was by cooling cheese whey to 0-5°C, adding calcium chloride, adjusting to pH 7.3, warming to 50°C, and removing the insoluble precipitate that formed by centrifugation or decantation. UF permeation flux rate of pretreated whey was about double that for control whey. Pretreated whey was essentially turbidity free, contained 85% less milkfat, 37% more calcium and 40% less phosphorus than whey. Pretreated whey WPC proteins were slightly more soluble at pH 3, but less functional for emulsification than whey WPC proteins. Neither whey WPC proteins nor pretreated whey WPC proteins was functional for foaming at 6% protein concentration.     

Formaldehyde Treated Whey Protein Concentrate for Lactating Dairy Cattle

Four lactating Holstein cows were fed isonitrogenous rations of urea-corn silage and a 15% crude protein pelleted grain ration containing whey protein concentrate (34% protein) either untreated or treated with 1% formaldehyde on a protein basis. The trial design was three periods double reversal with 12 days per period during which milk and digestibility were measured the last 4 days of each period. Apparent nitrogen digestibility (%), productive nitrogen retained (milk plus retained, g/day), and dry matter digestibility were 60.0 and 53.9, 89.0 and 103.8, and 67.4 and 63.2 for cows fed untreated and treated rations. Productive nitrogen as a percent of absorbed was greater for cows fed the formaldehyde treated ration, suggesting more efficient utilization of absorbed nitrogen. Milk production, milk fat percent and yield, and 4% fat-corrected milk were greater for cows fed the treated ration. Milk fatty acid content was similar. Total daily milk nitrogen, true protein nitrogen, and casein nitrogen yields were not significantly higher for the treated ration. No differences in serum urea and rumen ammonia were major. Rumen volatile fatty acids were higher in cows fed the untreated rations at 4 and 6 h postfeeding. Differences in serum concentrations of most individual essential amino acids between tail and mammary blood were greater for cows fed the treated ration.     

Spherosil-S Ion Exchange Process for Preparing Whey Protein Concentrate

Ion exchange whey protein concentrate (IEWPC) was produced from acid whey using Spherosil-S, a microporous silica bead cation exchange medium. About 80% of the total whey proteins were recovered by the ion exchange process. The composition of IEWPC was 63 - 66% protein, 1 - 2% lactose, 7 - 9% milkfat and 20 - 22% ash. Solubility, PAGE, reverse phase HPLC and Sephadex gel frltration results confirmed that the proteins in IEWPC had undergone substantial denaturation during their isolation. Several major problems encountered during the study were: generation of large volumes of column effluent, the need for concentration of column protein elutate fractions by ultrafiltration, column fouling and loss of protein solubility and functionality.     

Composition and Properties of Spherosil-QMA Whey Protein Concentrate

The Spherosil-QMA ion exchange process was used to prepare whey protein concentrate (WPC) from cheese whey. The process recovered about 64% of the proteins from whey as a 63% protein WPC. The WPC contained about 20.8% lactose, glucose, and galactose. The WPC proteins ranged in solubility from about 32–42% as a function of pH 3–7 and appeared to have undergone substantial denaturation by HPLC but not by palyacrylamide gel electrophoresis. The gelation properties of WPC were compared with those of commercial and ultrafiltration WPCs as a function of pH 3–7.5 and 0.0–0.15M NaCl and CaCl₂. The WPC did not function well as egg replacer in model cake and custard formulations.     

Acceptance of Cream Liqueurs Made with Whey Protein Concentrate

Cream-based liqueurs prepared with whey protein concentrate showed stability and were more preferred than a commercial cream-based liqueur. Variations in product preparation included level of ingredient used as well as order of ingredient addition. Product made with washed cream and ethanol added before homogenization was stable for 90 d at 40° C. Comparison of the most stable experimental product to a commercial liqueur by sensory evaluation showed no significant differences in sweetness, texture, smoothness, and overall preference. The commercial product showed more off-flavors and a heavier body than the most stable experimental samples.     

Heat-Induced Changes in the Proteins of Whey Protein Concentrate

Three-level fractional factorial experiments were used to study effects of heating conditions (pH, time, temperature, solids content, calcium addition) on whey protein concentrate. Increasing pH and temperature led to lower solubility at pH 4.6 and 7.0, lower sulfhydryl content, higher hydroxymethylfurfural, generally darker color, lower DNBS-available lysine and altered pepsin pancreatin digestion profiles. Mercaptoethanol and SDS demonstrated relative importance of disulfide and hydrophobic bonds on solubility loss. Polyacrylamide gel electrophoresis indicated heat stability of proteose peptones; susceptibility was greatest at pH 8.0, 95°C for β-lactoglobulin and α-lactalbumin, and pH 4.6, 95°C for bovine serum albumin. HPLC gel filtration showed that heating rendered a high molecular weight fraction undissociable by mercaptoethanol.     

High Pressure Effects on Emulsifying Behavior of Whey Protein Concentrate

Oil-in-water emulsions (0.4 wt% protein, 20 vol%n-tetradecane, pH 7) prepared with solutions of pressure-treated (up to 800 MPa) whey protein concentrate (WPC) as emulsifier give a broader droplet-size distribution than emulsions made with native untreated protein. There was a decrease in emulsifying efficiency with increasing applied pressure and treatment time. In contrast, pressure treatment of corresponding WPC emulsions made with the native protein had little effect on emulsion stability. In the pressure-treated emulsion the protein is probably already conformationally modified so that pressure has little additional effect. However, in solution the native structure of the whey protein is modified by pressure resulting in loss of emulsifying efficiency.     

Insolubilized Whey Protein Concentrate and/or Chicken Salt-Soluble Protein Gel Properties

Properties of gels prepared from five whey protein concentrates (WPC) with protein solubilities ranging from 27.5% to 98.1% in 0.1M NaCl, pH 7.0, chicken breast salt-soluble protein (SSP), or a combination of SSP and WPC at pH 6.0, 7.0 or 8.0 were compared. WPC did not form gels when heated to 65°C. SSP gels heated to 65°C were harder than those heated to 90°C at all pHs and hardness decreased as pH was increased. Hardness of combination gels heated to 65°C increased as WPC solubility decreased at all pHs; however, the opposite trend was observed at 90°C. Combination gels of the same WPC solubility at 65°C were more deformable than those heated to 90°C.     

Evaluation of Yield and Quality of Cheddar Cheese Manufactured from Milk with Added Whey Protein Concentrate

Cheddar cheese was produced from whole milk with blends of whey protein concentrates added. Two whey protein concentrate powders containing 35 or 55% protein were each reconstituted to a 15% (wt/wt) suspension and heat treated at 70°C for 15 min. Addition of the denatured whey protein concentrate suspension to the milk was at 5 or 10% by weight of the milk. Addition of reconstituted partially denatured whey protein concentrate increased cheese yields from 1.4 to 6.2% above those of the control on a 63% solids basis. The only significant (P<.05) increase in yield was from the 55% whey protein concentrate suspension at 10% replacement by weight of the milk. The correlation coefficient between percent denaturation in the whey protein concentrate and yield in this cheese was .62. Experimental cheese had decreased fat and total solids contents and increased total nitrogen, ash, and salt. Fat reduction varied from 4.3 to 18.2% below the control cheese, and total solids were from 1.7 to 8.9% below the control cheeses. Total nitrogen values of experimental cheese were from .73 to 5.64% above the control. Cheeses were evaluated organoleptically; more flavor defects were associated with increased whey protein concentrate in the experimental cheese. The most common criticism of the experimental cheese was an atypical (unclean) cheese flavor.     

Whey Protein Concentrate as a Proteinase Inhibitor in Pacific Whiting Surimi

The most effective inhibition of autolytic proteinase activity was found at 3% whey protein concentrate (WPC) with residual proteinase activity at 14.2%. WPC reduced papain and trypsin activities linearly with lowest residual activities of 8.7% and 41.4%, respectively. An unidentified high-molecular-weight protein was inhibitory for papain and trypsin with no inhibitory components detected at the region r 100,000. The highest shear strain of surimi was obtained with WPC at 4%. The values were 1.89 when rapidly cooked at 90°C for 15 min and 1.62 when pre-heated at 60°C for 30 min prior to cooking at 90°C.     

Prediction of Thermohydric History of Whey Protein Concentrate Droplets during Spray Drying

In this study, we analyzed heat and mass transfer phenomena occurring during spray drying of a whey protein concentrate at pilot scale. Conservation equations were written for both liquid droplets and humid air. Predicted results were then compared with experimental data: particle final moisture content, outlet air temperature, and humidity. The good adequacy found between experimental and predicted data allowed us to use the predicted values as a good indicator of thermohydric history followed by a droplet during drying. These results can also be used to help to find optimal process settings during production of spray-dried powders with specific properties.     

Dynamic Rheological Properties and Microstructure of Partially lnsolubilized Whey Protein Concentrate Gels

Viscoelasticity and microstructure of gels prepared with four whey protein concentrates (WPC) with solubilities from 27.5 to 98.1% in 0.1M NaCl, pH 7.0 were evaluated. Dynamic moduli were determined while 16% (w/w protein) WPC in 0.6M NaCl, pH 7.0, was heated isothermally at 90°C for 15 min. Storage moduli (G′) increased and tangent δ decreased when 80.0 and 98.1% soluble WPC were heated, whereas G' and tangent δ of 27.5 and 41.0% soluble WPC did not change. The 27.5% soluble WPC had the highest G' throughout the heating period. Rheological measurements suggested that globular aggregates observed in 80.0% and 98.1% soluble WPC were formed during heating, whereas aggregates in 27.5 and 41.0% WPC were present prior to heating.     

乳清浓缩蛋白可食用膜成膜工艺的研究

研究了乳清浓缩蛋白可食用膜的成膜工艺,分析了蛋白质浓度、甘油浓度和加热温度对可食用膜透水性和透氧性的影响,并确定了可食用膜阻隔性能的优化工艺参数。研究结果表明,可食用膜的阻水性随蛋白质浓度和甘油浓度的增大而下降,阻氧性随甘油浓度增大而下降。加热温度为70℃时,膜的阻水性和阻氧性达到最佳。响应面分析表明,当蛋白质浓度为100 g/L,甘油浓度为27 g/L,加热温度为69℃时,乳清浓缩蛋白可食用膜的综合通透性能为最佳,其透湿系数为0.004 35 g·mm/(m~2·h·kPa),透氧系数为0.134 cm~3·mm/(m~2·min·kPa)。     

Comparative Evaluation of Whey Protein Concentrate, Soy Protein Isolate and Calcium-Reduced Nonfat Dry Milk as Binders in an Emulsion-Type Sausage

The effects of various nonmeat binders on the yield and textural properties of knockwurst, an emulsion-type sausage product, were investigated. Three whey protein concentrate levels, calcium-reduced nonfat dry milk and soy protein isolate and an all-meat control were evaluated. Whey protein concentrate proved to be a viable binder alternative for specific emulsion-type meat products by providing similar stability, textural and sensory attributes in comparison to equal levels of soy protein isolate and calcium-reduced nonfat dry milk.     

酪蛋白糖巨肽超滤分离的工艺优化研究

目的:研究超滤分离酪蛋白糖巨肽的最优工艺参数,以达到最佳超滤通量性能。方法:采用超滤方法分离乳清浓缩蛋白(WPC80)中的酪蛋白糖巨肽,研究料液pH值、操作压力和温度等对膜渗透通量的影响。利用SDS-PAGE凝胶电泳技术分析超滤截留液的相对分子量分布。结果:实验表明溶液pH7.0、操作压力0.3MPa、温度45℃时膜渗透通量最高,超滤酪蛋白糖巨肽的截留率达到97.54%,产物纯度达到92.45%,经SDS-PAGE凝胶电泳测定,酪蛋白糖巨肽的平均分子量68.86%为30.47ku,31.14%为19.22ku。结论:超滤技术是将酪蛋白糖巨肽与其他乳清蛋白分离的有效方法。     

Flow Properties, Firmness and Stability of Double Cream Cheese Containing Whey Protein Concentrate

As estimated on-line, the viscosity after cooling of double cream cheese curd containing heat-denatured WPC (DCC +) increased from 1.4 Pa.s to 1.7 Pa.s when cooled to the range of 45°C to 24°C, and then decreased from 1.7 Pa.s to 1.0 Pa.s when cooled from 24°C to 15°C. The viscosity of DCC^- (without heat-denatured WPC) increased from 1.5 Pa.s to 2.2 Pa.s at temperature shift from 40°C to 15.5°C. The firmness of stored DCC + and DCC^-, respectively, decreased from 15.1N to 6.5N when cooled to temperatures from 45°C to 15°C, and from 17.9N to 9.9N when cooled from 40°C to 15.5°C, as recorded by cone penetrometry. The structure of DCC+ cooled to 15°C collapsed after penetrometry, and DCC+ cooled to 20°C destabilized during shearing in coaxial cylinder rheometer. A new phase in DCC+ based on milk fat globules liberated by cluster disruption may be the cause of the structural and textural instability.     

Evaluation of Corn Protein Concentrate: Extrusion Study

Functional properties of corn protein concentrate were evaluated after extrusion with a laboratory Brabender and a Wenger X-25 extruder. Bulk density, water content and hardness after rehydration were used as criteria for textural comparison among extrudates. Results indicated that corn protein concentrates resulting from either aqueous (CPC-A) or ethyl acetate (CPC-E) extraction were more suitable for extrusion applications than the one resulting from hexane extraction. A blend containing corn protein concentrate and soy flour at the ratio of 15:85 was good for chunks and granules extrusion in the pH range 7.0 - 7.3. In a dry spinning process which requires a dough with high cohesiveness for fiber formation, a blend containing 21% of corn protein concentrate, 20% soy isolate, and 59% soy concentrate at a natural pH was satisfactory.