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At least 19 recordsLinked to original sources
PubMed2026

Screening of Fermentative Strains for Reducing the Allergenicity of a Whey Protein-Soy Protein System and Genomic Characterization of the Selected Strain.

Dual-protein systems combining whey protein isolate (WPI) and soy protein isolate (SPI) offer complementary nutritional benefits but are limited by the presence of major allergens. Lactic acid bacteria (LAB) fermentation provides a promising strategy to mitigate this limitation. In this study, Lacticaseibacillus paracasei JM053, selected from 13 LAB strains based on phenotypic screening, significantly reduced the in vitro allergenicity of the dual-protein system, increasing the IgE-binding inhibition rate to 48.75%. Whole-genome sequencing and characterization of JM053 revealed a comprehensive proteolytic system, including the proline-specific peptidase genes pepX and pepQ, which may contribute to the degradation of allergenic peptide sequences. Combined with in silico bioinformatic analysis, potential cleavage sites within the linear epitopes of the dual-protein system were predicted based on the substrate specificity of the identified proteases, offering a testable hypothesis for the strain's mechanism of action. In addition, in vitro safety assessment and genomic analysis supported the safety potential, stress tolerance, and probiotic characteristics of JM053. Collectively, this study provides a valuable candidate strain for the development of hypoallergenic dual-protein products and offers preliminary genomic insights into LAB-mediated allergenicity reduction.

Lacticaseibacillus paracasei↗
PubMed1978

Fortification of soft drinks with protein from cottage cheese whey.

Cottage cheese whey protein concentrates, prepared by preconcentration by ultrafiltration followed by gel permeation to remove low molecular weight materials, have the solubility, stability and flavor that make them suitable for fortification of soft drinks and related products. These concentrates are characterized by high levels of "available" lysine and by amino acid compositions indicating good nutritional value. Carbonated beverages prepared with conventional beverage ingredients and containing up to 1% by weight of the total beverage of added whey protein maintained clarity, color, and flavor during 203 days storage at room temperature. Spray dried whey protein concentrates were incorporated without adverse effects into commercial "ade" type powders. Clarity of 1% protein solutions at pH 2--3.5 was not impaired by heating for 6h at 80 degree, but some structural change occurred since an average of 37% of the protein precipitated on shifting pH to 4.7. Increased stability against heat denaturation under acidic conditions was conferred by some soft drink ingredients. Added sucrose reduced protein denaturation by 1/2 but sodium saccharin had no effect. The type of acid used also altered protein denaturation rate. While properly isolated whey protein concentrates have functional properties necessary for soft drink fortification, feasibility of use will depend upon cost.

Beverages↗
PubMed2026

Protein isolation markedly enhances in vitro digestibility, nutritional quality, and bioactivity of fungal mycelial proteins.

Fungal mycelial proteins are promising sustainable protein sources, yet their nutritional utilization is often limited by structural constraints. This study systematically evaluated the effects of protein isolation on the proteomic composition, gastrointestinal digestion behavior, amino acid utilization, and bioactivity of Pleurotus citrinopileatus mycelial proteins. Quantitative proteomics identified 3591 proteins, of which 3374 were shared between mycelial flour (PCMF) and protein isolate (PCMPI), indicating that PCMPI primarily represents the soluble proteome fraction. In vitro digestion revealed that PCMPI exhibited significantly higher digestibility (93.98%) than PCMF (42.98%) (p&#xa0;<&#xa0;0.05), reaching levels comparable to whey protein isolate. Enhanced enzymatic accessibility in PCMPI promoted rapid peptide generation during the gastric phase and efficient amino acid release during the intestinal phase, resulting in higher peptide (634.76&#xa0;mg/g) and free amino acid levels (341.69&#xa0;mg/g) at the digestion endpoint. Consequently, PCMPI achieved a balanced amino acid profile with a PDCAAS of 1.0. Moreover, its digestion products exhibited stronger antioxidant activity (IC&#x2085;&#x2080;&#xa0;=&#xa0;8.36&#xa0;mg/mL) and ACE inhibitory activity (IC&#x2085;&#x2080;&#xa0;=&#xa0;15.65&#xa0;mg/mL) compared with PCMF. Mechanistically, protein isolation disrupted the cell wall matrix, shifting digestion from a structure-limited to an accessibility-driven regime. Collectively, these findings demonstrate that protein isolation markedly enhances the digestibility, nutritional quality, and functional potential of mycelial proteins, supporting their application as high-value sustainable protein ingredients.

Digestion↗
PubMed1976

Effect of psychrotrophic bacteria from raw milk on milk proteins and stability of milk proteins to ultrahigh temperature treatment.

The effects of psychrotroph growth in raw milk on proteins of mils and on the response of milk proteins to heat treatments with ultrahigh temperature were studied. Ten gram-negative psychrotrophs isolated from raw milk readily attacked raw milk proteins. Kappa- and beta-casein were most susceptible although some of the isolates also attacked the whey proteins. Detectable proteolysis did not require large psychrotroph populations. A 10 to 20% decrease in kappa-casein during 2 days at 5 C accompanied growth of one isolate to a population of only 10,000/ml. Growth of psychrotrophs in raw milk predisposed the proteins to deleterious effects of ultrahigh temperature treatments. Ultrahigh temperature treatment by direct steam injection had little effect on raw milk caseins and decreased alpha-lactalbumin and beta-lactoglobulin by 21% and 34%, respectively. Milk that had undergone proteolysis exhibited decreased detectable kappa-, beta-, and alphas-caseins and increased loss of beta-lactoglobulin as a result of ultrahigh temperature treatment. Milk suffering extensive kappa-casein degradation coagulated during ultrahigh temperature treatment. Coagulation during or shortly after heating increased with severity of heat treatment and size of psychrotroph population.

Animals↗
PubMed1978

Purification and partial characterization of a unique group of phosphoproteins from rat milk whey.

A group of four electrophoretically distinct but related proteins has been isolated from rat milk whey. These have been classified as P.1 to P.4 in order of their decreasing electrophoretic mobility in an alkaline buffer system. All four members of this group of proteins are immunologically identical apparently constitute a single protein which is differentially phosphorylated in the ratio of 3:2:1:0. Sodium dodecyl sulfate gel electrophoresis yielded constant estimates of molecular weight of approximately 20,700. Enzymatic dephosphorylation of purified P.1 generated the other three members of the group, demonstrating the commonality of the peptide component. This group of proteins in total makes a significant contribution of the total whey proteins being approximately 5 mg/ml in whole rat milk in the approximate proportion of 1:1.5:2:1.5. The P.1, P.2, and P.3 were isolated in sufficient quantities to permit further characterization. The partial amino acid analyses of each of the three forms were similar. They had commonextinction coefficients, E1(1)% cm A280, of 4.9 and A280/A290 ratio of about 1.36.

Amino Acids↗
PubMed1975

A study of the association of human secretory component with IgA and IgM proteins.

Human secretory component (SC) was isolated from colostral whey, and the binding of 125I-SC to purified IgA and IgM monoclonal proteins was studied using two methods to separate free from immunoglobulin-bound 125I-SC: a) gel filtration on Sephadex G-200, and b) precipitation of 125I-SC-Ig complexes with anti-Ig antibody. Both IgA dimeric proteins and IgM pentamers bound 125I-SC with approximately one SC-binding site per mole of polymer and similar affinity. Assuming a reversible equilibrium, an apparent association constant congruent to 10-8 M-1 was calculated to govern the binding of 125I-SC to immunoglobulin polymers. The assignment of a single association constant may be an oversimplication, particularly for the case of IgA polymers, since evidence was obtained that disulfide bonds were formed in the 125I-SC-IgA complex. Despite the complexity of the reaction, binding of 125I-SC to both IgA and IgM polymers could be analyzed by standard methods of saturation analysis, and both were shown to have a similar affinity for 125I-SC. No differences were noted in the affinity of 125I-SC binding to the IgA1 and IgA2 subclasses. Binding of monomeric IgA and IgM proteins could not be measured and was at least 100-fold lower than that found for IgA and IgM polymers. Complexes of 125I-SC with IgA dimers were presumed to involve covalent bond formation, since these complexes did not dissociate in guanidine-HCl. One IgA2 trimer did not form a covalent bond since it was completely dissociated in guanidine. In contrast, 125I-SC-IgM complexes were dissociated in denaturing solvent, indicating that such complexes were held together primarily by non-covalent bonds. Experiments with (Fc)5 mu isolated by high temperature tryptic digestion of IgM showed that binding of 125I-SC was to the Fc region of IgM proteins. It was suggested that the binding of SC with similar affinity to both IgA and IgM polymers may be important in the biologic function of both these immunoglobulin classes.

Absorption↗
PubMed1977

Folate binding by human milk protein.

Human whey was subjected to gel chromatography. Two folate binding protein fractions wer eluted: a major one (Mr congruent to 30,000) and a minor one (Mr greater than 200,000). The former folate binding fraction (FB) could be isolated from whey by means of ion exchange chromatography. Equilibrium dialysis experiments with whey and isolated FB indicated the existence of cooperatively interacting sites in folate binding. The folate analogue methotrexate inhibited folate binding. Inhibition was apparently of a competitive type since methotrexate did not reduce maximum binding capacity. Cooperativity was lost in the presence of methotrexate. Binding affinity was inversely proportional to the concentration of FB suggesting involvement of a polymerizing protein system in binding. None of the other fractions eluted on the ion exchange column could bind folate.

Binding Sites↗
PubMedDate not supplied

Balanced intraintestinal nutrition: digestion, absorption and biological value of selected preparations of milk proteins.

The absorption of an enzymatic hydrolysate of whey proteins, hydrolysates of milk proteins and casein, 7% hydrolysate of bovine blood produced by Polfa under the trade name "Aminokwasy", and a standard mixture of amino acids from isolated small intestine loop of dogs and rats was compared. The composition of amino acids of the initial proteins and hydrolysates obtained from these proteins was determined. The biological value of selected proteins and hydrolysates was assessed determining the mean weight gain, nitrogen content of the body, urinary excretion of urea and creatinine, blood urea level and NPU. No significant differences were found in the absorption of nitrogen from the hydrolysate of milk and whey proteins. The nutritional value of whey protein hydrolysate was, however, slightly higher than that of an analogous hydrolysate of milk proteins. It seems that of all tested proteins whey hydrolysate (free of lactose) is the most suitable source for obtaining preparations for no-residue intraintestinal feeding.

Amino Acids↗
PubMedDate not supplied

Balanced intraintestinal nutrition. A preparation for intraintestinal no-residue nutrition.

The investigations were carried out on dogs and male Wistar rats using the method of isolated intestinal loops. The absorption of nitrogen from a preparation was studied. The protein component of the preparation was an enzymatic hydrolysate of whey proteins, milk proteins, casein and a 7% bovine blood hydrolysate manufactured by Polfa. Comparative investigations were carried out on the effect of the protein component on the absorption of fat from the tested preparation. No significant differences were found in nitrogen absorption from the hydrolysates of milk proteins administered in the form of a protein-fat-carbohydrate emulsion or in fat absorption depending on the protein component. On the basis of theoretical assumptions and experiments on laboratory animals the composition of a preparation for balanced no-residue intraintestinal nutrition was elaborated in which the protein component was a hydrolysate of whey proteins without lactose and the fat component was soybean oil.

Animals↗
PubMed1975

Isolation of porcine secretory immunoglobulin A by affinity chromatography and determination of its component chains.

Porcine secretory immunoglobulin A (SIgA) was isolated in a single step from porcine milk whey by affinity chromatography, using antiporcine alpha-chain specific antibody linked to CNBr-activated agarose. The isolated SIgA contained no other proteins detectable by immunodiffusion of immunoelectrophoresis. After reduction and alkylation with dithiothreitol and iodoacetamide, the SIgA was chromatographed on gel equilibrated with 6.0 M urea and 1.0 M propionic acid. Polyacrylamide gel electrohoresis of the fractions eluted revealed the presence of light chain, alpha-chain secretory component, and J-chain.

Animals↗
PubMed1976

The whey proteins of the milk of red deer (Cervus elaphus L.). A homologue of bovine beta-lactoglobulin.

1. The whey proteins from the milk of red deer are compared with those of cattle. Gel chromatography and electrophoresis showed a close similarity between the whey proteins of the two species in the size, mobility and relative amounts of the main constituents and in the changes in their relative amounts with time after parturition. 2. The major constituent of the deer whey was isolated. It appeared to be homologous with bovine beta-lactoglobulin and had the following properties: m=-5.2X10(-9)m2-s-1-V-1 at 4 degrees C and pH 8.6; pI=5.17; S020, w =2.89S; v=0.748 ml/g; E1g/dl 1cm= 9.12 at 278 nm; deltan/c=1.794 X 10(-3)dl/g at 579 nm (all at 20 degrees C except m). Its molecular weight was that of a dimer with a subunit weight of 18 000. 3. Amino acid analyses of this protein, adjusted to lysine = 15 residues showed that it contains one more residue of aspartic acid, alanine and methionine and one less glutamic acid residue and two less leucine residues than bovine beta-lactoglobulin A. 4. On starch-gel electrophoresis at pH 8.2, this protein migrated at the same rate as bovine beta-lactoglobulin B, although its isoelectric point is close to that of the bovine A variant. Milk from three out of 27 hinds examined showed a variant. This migrated in starch gel at the same rate as the bovine A variant but had a more acid pI = 5.02. 5. The two species whose milk whey proteins are compared represent two different families of ruminants. The similarities found support the view that the milk whey proteins of the bovids are probably typical of the suborder as a whole.

Amino Acids↗
PubMed1975

[Mass transfer in production of milk protein coprecipitates].

During the last twenty years heat coagulation has become a more important technical procedure for the isolation of milk proteins because of its very efficient utilization of raw material. Experiments are reported to get approximation equations for the mass transfer in the production of milk protein coprecipitates from skim milk and mixtures of skim milk with rennet and acid whey by means of statistical planning and interpreting of experiments. Good exactness was reached. The coagula consist of casein fractions, whey protein fractions, calcium, and phosphates. The products are thermically rather stable, sensorically indifferent and contain water insoluble protein. They are suitable to improve the fat: protein ration of sausages, but also for the protein enrichment of other foods and for dietetic purposes.

Calcium↗
PubMed1978

Purification and characterization of rat alpha-lactalbumins: apparent genetic variants.

Rat alpha-lactalbumin, from the milk of Fischer 344 (CDF) rats, was isolated and purified by a combination of gel filtration and diethylaminoethyl-cellulose ion exchange chromatography. Three electrophoretically distinct proteins had alpha-lactalbumin activity. Staining for carbohydrate indicated that at least two of the three forms were glycoproteins. The low molecular weight protein fraction from the wheys of two additional strains of laboratory rat were compared to ascertain whether the composition of this fraction was common in the divergent strains. Outbred Wistar and Long-Evans dams yielded wheys containing up to six forms of alpha-lactalbumin. Either one or both of two groups of three alpha-lactalbumins were in a given milk sample. The two groups of three alpha-lactalbumins appear to represent two genetic variants upon which is imposed a polymorphic character. All forms of alpha-lactalbumin, within and between strains, were immunologically identical.

Animals↗
PubMed1975

Trypsin inhibitor from cow colostrum. Isolation, electrophoretic characterization and immunologic properties.

Trypsin inhibitor from cow colostrum has been purified by affinity chromatography of colostral proteins on insolubilized trypsin. The method described compares favourably, in both simplicity and yield, with previous methods developed for the isolation of this inhibitor. Gel electrophoresis followed by characterization of antitrypsin activity allows the demonstration of four molecular forms of bovine colostral trypsin inhibitor in both crude colostral whey and purified preparations of the inhibitor. Immunoelectrophoresis of each of these materials with antisera specific for this inhibitor reveals a single precipitation line of broad anodic mobility. By immunodiffusion tests, the precipitation lines in preparations of purified inhibitor and colostral whey appear immunologically identical. In contrast, absence of crossed reactivity was observed between bovine colostral trypsin inhibitor and trypsin inhibitors of bovine serum. This strongly suggests the high specificity of this inhibitor as a colostral and milk constituent.

Animals↗
PubMed1979

Utilization of milk proteins as starting materials for other foodstuffs.

The modern food-processing industry is placing more and more emphasis upon the utilization of protein ingredients to provide specific functional properties to a wide range of formulated foods. Isolated milk protein products represent an important and valuable source of protein ingredients due to their recognized superior nutritional, organoleptic and functional properties. This paper provides up-to-date information on the quantities, production processes, composition, general properties, and specific functional properties of the major milk protein products, e.g. caseinates, co-precipitates, lactalbumin, whey protein concentrates and milk blends. The subject of chemical and enzymic modification to improve certain functional properties of milk proteins is considered briefly.

Animals↗
PubMed1978

Isolation and partial characterization of rate casein proteins.

Casein was isolated from rat milk by high speed centrifugation. Polyacrylamide disc gel electrophoresis of the whole casein yielded three major protein zones designated C.1, C.2, and C.3 in order of their decreasing electrophoretic mobility in the alkaline system. Zone 3 subsequently contained two possibly related bands, C.3.1 and C.3.2. The presence of phosphate in all four zones was indicated by staining and conformed by phosphorus-32 labeling studies. A glycoprotein character was indicated by all zones. Separation of the constituents of rat casein by diethylaminoethyl-cellulose ion exchange chromatography yielded the same four major protein entities. Three milk-specific phosphoproteins unique to rat whey cluted from such columns in the same general region as the casein constituents but appear to be otherwise unrelated to the four major components of micellar casein. Gel electrophoresis in sodium dodecyl sulfate systems yielded apparent molecular weight estimates of approximately 24,000 for C.1, 38,000 for C.2, and 28,000 for c.3.1 and c.3.2.

Animals↗
PubMed1976

Isolation and characterization of murine lactoferrin.

Lactoferrin, a non-heme, iron-binding glycoprotein, was isolated from mouse milk. The purification procedure involved an initial centrifugation to remove much of the casein and to separate the fat from the whey, followed by ammonium sulfate precipitation and chromatography on carboxymethyl-Sephadex. The lactoferrin preparation obtained was highly purified as judged by polyacrylamide gel electrophoresis under both non-denaturing and denaturing conditions, and the presence of lysine as the only NH2-terminal amino acid. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate indicated a single component having a molecular weight of 78 000 +/- 2800. Sedimentation equilibrium ultracentrifugation studies suggested that in addition to monomers of molecular weight 75 000 +/- 1000, other oligomeric forms of the protein were also present. Amino acid and amino sugar analyses revealed that there were 5 methionine, 10 histidine, 10 tryptophan and 5 glucosamine residues per mol of protein. Isoelectric focusing of lactoferrin in a polyacrylamide gel stabilized pH gradient indicated a single component having an isoelectric point of about 9; however, depending on the preparation examined, a range of 8.7-9.6 was noted. A single precipitin line was observed with rabbit anti-mouse lactoferrin when examined by immunodiffusion and immunoelectrophoresis. No immunological cross-reaction was observed between mouse lactoferrin and mouse transferrin.

Amino Acids↗