Production of a high gel strength whey protein concentrate from cheese whey

In order to develop a process for the production of a whey protein concentrate (WPC) with high gel strength and water-holding capacity from cheese whey, we analyzed 10 commercially available WPC with different functional properties. Protein composition and modification were analyzed using electrophoresis, HPLC, and mass spectrometry. The analyses of the WPC revealed that the factors closely associated with gel strength and water-holding capacity were solubility and composition of the protein and the ionic environment. To maintain whey protein solubility, it is necessary to minimize heat exposure of the whey during pretreatment and processing. The presence of the caseinomacropeptide (CMP) in the WPC was found to be detrimental to gel strength and water-holding capacity. All of the commercial WPC that produced high-strength gels exhibited ionic compositions that were consistent with acidic processing to remove divalent cations with subsequent neutralization with sodium hydroxide. We have shown that ultrafiltration/diafiltration of cheese whey, adjusted to pH 2.5, through a membrane with a nominal molecular weight cut-off of 30,000 at 15 degrees C substantially reduced the level of CMP, lactose, and minerals in the whey with retention of the whey proteins. The resulting WPC formed from this process was suitable for the inclusion of sodium polyphosphate to produce superior functional properties in terms of gelation and water-holding capacity.     

Production of an exopolysaccharide-containing whey protein concentrate by fermentation of whey

Using whey as a fermentation medium presents the opportunity to create value-added products. Conditions were developed to partially hydrolyze whey proteins and then ferment partially hydrolyzed whey with Lactobacillus delbrueckii ssp. bulgaricus RR (RR; an EPS-producing bacterium). In preliminary experiments, pasteurized Cheddar cheese whey was treated with Flavourzyme to partially hydrolyze the protein (2 to 13% hydrolyzed). Fermentation (2 L, 38 degrees C, pH 5.0) with RR resulted in EPS levels ranging from 95 to 110 mg of EPS per liter of hydrolyzed whey. There were no significant differences in the amount of EPS produced during fermentations of whey hydrolyzed to varying degrees. Since a high level of hydrolysis was not necessary for increased EPS production, a low level of hydrolysis (2 to 4%) was selected for future work. In scale up experiments, whey was separated and pasteurized, then treated with Flavourzyme to hydrolyze 2 to 4% of the protein. Following protease inactivation, 60 L of partially hydrolyzed whey was fermented at 38 degrees C and pH 5.0. After fermentation, the broth was pasteurized, and bacterial cells were removed using a Sharples continuous centrifuge. The whey was then ultrafiltered and diafiltered to remove lactose and salts, freeze-dried, and milled to a powder. Unfermented hydrolyzed and unhydrolyzed whey controls were processed in the same manner. The EPS-WPC ingredients contained approximately 72% protein and 6% EPS, but they exhibited low protein solubility (65%, pH 7.0; 58%, pH 3.0).     

Characterisation of a whey protein hydrolysate as antioxidant

A whey protein hydrolysate was fractionated by size-exclusion chromatography to investigate the effectiveness of individual peptide fractions as (i) deactivators of hypervalent haeme iron, (ii) as radical scavengers, and (iii) as iron chelators. The reduction of ferrylmyoglobin, MbFe(IV)O, to metmyoglobin, MbFe(III), by the peptide fractions was found to follow first-order kinetics for excess peptide. The fractions with the highest rate of reduction of ferrylmyoglobin also exhibited most efficient radical scavenging as determined for the stable Fremy's salt radical. Inactivation of catalytic free ion by peptide fractions, as examined by their ability to inhibit formation of the ferrozine-Fe²⁺ complex, showed highest inhibition for the fractions with least scavenging capacity of the Fremy's salt radical. Radical scavenging of 1-hydroxylethyl radicals generated in Fenton reactions showed antioxidant activity for low peptide concentration, but prooxidative activity for increasing concentration. Specific whey peptide fractions, may be combined as a food additive to optimise antioxidative activity.     

Process development for a novel milk protein concentrate with whey proteins as fibrils

Milk protein concentrate (MPC) is a preferred ingredient to provide nutritional and functional benefits in various dairy and food products. Altering the protein configuration and protein-protein interactions in MPC can provide a novel functionality and may open doors for new applications. The fibrilization process converts the globular structure of whey proteins to fibrils and consequently increases viscosity and water holding capacity compared with the native protein structure. The objective of the current work was to selectively convert the whey proteins in MPC as fibrils. For this purpose, simulated control model MPC was prepared by combining solutions of micellar casein concentrate (MCC) and milk whey protein isolate (mWPI) to give casein and whey protein in an 80:20 ratio. The mWPI solution was converted to fibrils by heating at low pH, neutralized, and combined with MCC solution similar to control model MPC and termed “fibrillated model MPC.” Thioflavin T fluorescence value, transmission electron microscopy, and gel electrophoresis confirmed the fibril formation and their survival after neutralization and mixing with MCC. Further, the fibrillated mWPI showed significantly higher viscosity and consistency coefficient than nonfibrillated mWPI. Similarly, fibrillated model MPC showed significantly higher viscosity and consistency coefficient compared with control model MPC. Hence, the fibrillated model MPC can be used as ingredient to increase viscosity. Heat coagulation time was found to be significantly higher for control model MPC compared with fibrillated model MPC.     

Production of whey protein isolate hydrolysate fractions with enriched ACE-inhibitory activity

A study on the enrichment of angiotensin-converting enzyme (ACE) inhibitory activity in whey protein isolate (WPI) hydrolysate fractions is presented. A previously identified low molecular mass fraction (1 kDa permeate) of an enzymatically hydrolysed heat-treated WPI with elevated ACE-inhibition (IC₅₀ = 0.23 g L⁻¹) was subjected to cascade membrane ultrafiltration (UF) and diafiltration steps at lab-scale. Assaying for ACE-inhibition revealed that the 1 kDa retentate demonstrated the highest ACE-inhibitory activity (IC₅₀ = 0.17 g L⁻¹). Isoelectric focussing (IEF) of the hydrolysate fraction further increased ACE-inhibition in fractions collected within the pH range 6.1–6.6. Overall, both UF and IEF enriched the ACE inhibitory activity in the original fraction by ∼52%, demonstrating the potential for enrichment of bio-functional activities in enzymatic hydrolysates of whey proteins.     

一种新型乳清碳酸饮料的制作工艺

介绍了一种将脱盐乳清粉配制成10%的水溶液,用β-半乳糖苷酶酶解降低其乳糖含量,经两组串联超滤装置处理得到澄清的饮料原液,最后调配加工成澄清型低乳糖碳酸饮料的制作工艺。结果表明,用以上处理方法可制得具有奶香风味、口感清爽并可供长期保存的乳清碳酸饮料。     

奶油及乳清分离

<正> 国外许多以牛奶为原料衍生出来的大宗产品稀奶油,以及副产品乳清等,其分离处理及工艺已达到成熟的工业技术,实在值得国内同业借鉴。奶油分离奶油分离技术基本可分为高温奶油分离以及低温奶油分离。高温奶油分离     

Production of low antigenic cheese whey protein hydrolysates using mixed proteolytic enzymes

This study examined the effect of different proteolytic enzymes on the production of cheese whey protein (CWP) hydrolysates with low antigenicity. Four enzyme combinations (1:1) trypsin + papain W‐40 (TP), trypsin + neutrase 1.5 (TN), papain W‐40 + protease S (PP) and papain W‐40 + neutrase 1.5 (PN) were added at the rate of 1% of the CWP and it was incubated for 15, 30, 60, 90, 120 and 180 min at 50 °C. CWP hydrolysis and its non‐protein nitrogen concentrations were higher with TP and TN compared with PP and PN at all incubation times. The SDS‐PAGE revealed complete removal of α‐lactalbumin (α‐LA) and β‐lactoglobulin (β‐LG) from hydrolysates produced by trypsin‐containing enzyme mixtures. Reverse‐phase HPLC analysis ascertained the CWP hydrolysis and SDS‐PAGE results. The lowest antigenicity in CWP hydrolysates was observed with the use of trypsin‐containing enzyme mixtures compared with other enzyme combinations. Present results suggested that TP and TN combinations were the most effective for CWP hydrolysis for the removal of β‐LG from CWP. Further research is warranted to identify the peptides in CWP hydrolysates produced with these enzyme combinations that may help enhance the utilisation of whey protein in human food. Copyright © 2007 Society of Chemical Industry     

Development and characterisation of whey protein micro-beads as potential matrices for probiotic protection

This study evaluated the efficacy of whey protein isolate (WPI) as an encapsulation matrix for the maintenance of Lactobacillus rhamnosus GG viability during simulated gastro-intestinal studies. Micro-bead characteristics were investigated using microscopy, chromatography, laser diffractometry and zeta potential analysis. Heat-treated WPI (11%, w/v) blended with stationary phase cultures demonstrated an instant gelation impetus in acetate buffer (0.5 M), tempered to 35 °C in the presence of Tween-20 (0.04%). Atomic force microscopy (AFM) demonstrated that micro-bead extrusion at pH 4.6 fuelled strong cohesive interactions within protein-probiotic amalgams; an electrostatic alliance further highlighted by zeta potential analysis. Optimization of encapsulation conditions generated self-supporting structures (200 ± 1.2 μm) with high micro-bead strength and individual loading capacity of 2.7 × 10⁴ cfu/micro-bead. Plate enumeration demonstrated that micro-bead extrusion had no detrimental effect on cell viability due to the perpetuation of stationary phase concentrations (10⁹ cfu/mL). This finding was further validated by LIVE/DEAD microscopy staining, which visualized the homogenous distribution of live probiotics throughout micro-bead matrices. Following 3 h in vitro stomach incubation (pH 1.8; 37 °C), micro-beads laden with 10¹⁰ cfu demonstrated acid-stability and peptic-resistance, characteristics required for optimum probiotic refuge. However, enzyme-activated intestinal conditions catalysed a synergistic response engaging rapid matrix disintegration and controlled probiotic release. Matrix digestion was monitored by chromatography, which witnessed the sequential release of peptides <2 kDa after 30 min. In conclusion, this study led to the development and design of a protein encapsulation polymer based on congruent matrix interactions for reinforced probiotic protection during challenging situations for their targeted delivery to intestinal absorption sites.     

Production and partial purification of proteases from Aspergillus oryzae grown in a medium based on whey protein as an exclusive nitrogen source

Several attempts have been made to incorporate whey proteins into curd to increase cheese yield. For some types of cheese, degradation of whey proteins that have been incorporated into the curd would be required to obtain acceptable flavor and texture. On the basis of the high potential for protease synthesis in Aspergillus oryzae, sodium nitrate as a nitrogen source in a minimal medium for fungi, known as Czapek-Dox medium, was replaced with whey protein isolate to induce the protease to hydrolyze whey protein using A. oryzae AHU7146. A solid-phase medium adjusted to pH 6 was suitable for this purpose when incubation was carried out at 25°C for 2 wk. The application of column chromatography enabled the resolution of 3 proteolytic components (1, 2, and 3). With respect to optimal temperature and zymographic analysis, component 1 was similar to component 3. In contrast, component 2 was less abundant than the other components and exhibited activity in the alkaline pH region. The degradation of β-lactoglobulin and α-lactalbumin in whey protein isolate solution by the crude enzyme was primarily attributed to the action of components 1 and 3, based on HPLC analysis and the N-terminal amino acid sequences; however, zymography demonstrated evident proteolysis due to component 2. Because heat-denatured whey protein aggregates were digestible by the crude enzyme, the proteolytic system from A. oryzae has the potential as an additive to stimulate the ripening of cheese enriched with whey protein.     

Paper and whey as a feedstuff for ruminants.

Eleven papers were compared for absorption of whey and for digestibility in vitro. Papers were squared, ground, and soaked in whey for 1, 5, and 15 min and for 1, 6, 24, 48, and 72 h. Digestibility in vitro was determined on minimum and maximum whey absorption of each squared and ground paper sample. Whey absorption by squared papers increased with time. Ground samples absorbed more whey than squared ones and maximum quantities were absorbed with 1 to 5 min. Mean percent absorptions for ground telephone book covers, glossy magazines, computer cards, computer printout sheets, daily newsprint, telephone directory yellow pages, cardboard box, feedsacks, brown bags, telephone directory white pages, and coasters were: 31.0, 35.2, 35.4, 36.5, 43.9, 47.9, 51.0, 51.4, 51.7, 55.6, and 67.4. For seven papers, addition of whey increased digestibility. Four papers were either unchanged or decreased in digestibility. This depression of digestibility may have resulted from the high fat content of whey used. Based on in vitro digestibilities, we conclude that it is possible to recycle selected paper/whey combinations through ruminants.     

乳清蛋白产品的发展趋势

乳清蛋白产品提供了理想的食品原料的营养应用.乳清蛋白由于其高含量的必需氨基酸,高消化率和生物价值,被广泛认为具有非常高的营养品质.     

大豆黄浆水中乳清蛋白和低聚糖制备研究进展

大豆黄浆水是豆腐和大豆分离蛋白生产过程中排放的高浓度废水,其BOD5(生物需氧量)、COD值(化学需氧量)远远高于国家规定的排放标准,由于大豆黄浆水中含有多种生理活性物质,具有很好的商业开发价值,为此文中阐述了大豆黄浆水中乳清蛋白和低聚糖的制备和检测方法.     

Production of antioxidant hydrolyzates from a whey protein concentrate with thermolysin: Optimization by response surface methodology

Whey protein concentrate (WPC) enriched in β-lactoglobulin (β-Lg) was hydrolyzed using Corolase PP^® and thermolysin to produce hydrolyzates with antioxidant activity. The optimization of the main experimental variables involved in the process, such as type of enzyme, and hydrolysis conditions, concretely enzyme to substrate ratio, time and temperature, were evaluated using response surface methodology. A central composite circumscribed (CCC) design was employed to study the effect of the experimental variables on the antioxidant activity determined by radical scavenging potency. The parameters of the model were estimated by multiple linear regression, and the highest radical scavenging activity (2.57 μmol Trolox/mg protein) was found in WPC hydrolyzed with thermolysin after 8 h at 80 °C and an enzyme/substrate ratio of 0.10 (w/w). Nineteen β-Lg derived peptides were identified by RP-HPLC-MS/MS in this hydrolyzate. Of special interest are peptides LQKW f(58-61) and LDTDYKK f(95-101), which amino acid composition makes them potential contributors on the radical scavenging activity detected.     

Antioxidant properties of whey protein hydrolysates as measured by three methods

Four microbial proteases (Alcalase, Flavourzyme, Neutrase and Protamex) were used for the preparation of whey protein hydrolysates. The aim of this research was to find out whether these hydrolysates can be used as a source of whey derived antioxidants. Hydrolyzed samples, including their unhydrolyzed protein solutions were tested by the ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) decolorization assay, by the total radical-trapping potential method and by the assay of liposomes peroxidation (fluorescence photometry). Antioxidant properties were enhanced by hydrolysis in most of cases. Alcalase hydrolysates were found as the most effective antioxidants as determined by ABTS assay (~50% of antioxidant activity at 0.1 mg ml⁻¹ of hydrolysate in reaction) and fluorescence photometry. Liposomes were oxidized ~50% less (1.1 μM of α-tocopherol equivalent) with Alcalase hydrolysates additive (at 5.85 mg ml⁻¹ of hydrolysate in reaction). Hydrolysates did not inhibit the oxidation of liposomes at concentrations below 1.0 mg ml⁻¹ in reaction. On the contrary, results of total trapping potential method did not agree with findings observed in other tests. In this assay, Neutrase hydrolysates showed the best antioxidant properties. Pro-oxidant properties were observed in solutions containing (prior to the enzyme Protamex addition only) intact whey protein as determined by the measurement of the liposome peroxidation. The ABTS assay was optimized for the evaluation of the antioxidant activity in whey protein hydrolysates. The reaction time should be prolonged to avoid underestimation of the antioxidant activity.