Milk Proteins, Quantitative Ionophoretic Determination of Some Whey Proteins in Skim Milk

1957 ◽  
Vol 5 (7) ◽  
pp. 532-538 ◽  
Author(s):  
Abraham Leviton
Keyword(s):  
Whey Proteins ◽  
Skim Milk ◽  
Milk Proteins

A method for determination of macropeptide by cation-exchange fast protein liquid chromatography and its use for following the action of chymosin in milk

1991 ◽  
Vol 58 (3) ◽  
pp. 321-328 ◽  
Author(s):  
Joëlle Léonil ◽  
Daniel Mollé
Keyword(s):  
Quantitative Determination ◽  
Cation Exchange ◽  
Soluble Fraction ◽  
Whey Proteins ◽  
Skim Milk ◽  
Exchange Chromatography ◽  
Chromatographic Technique ◽  
Cation Exchange Chromatography ◽  
Preparative Scale

SummaryCation-exchange chromatography on a Mono S column (Pharmacia) was used to separate macropeptide from whey proteins. Macropeptide was eluted by 0·1 M-NaCl in a 20 mM-KCl–HCl buffer, pH 2. This technique was suitable for quantitative determination of macropeptide in rennet whey and also for following the action of chymosin on κ-casein in skim milk. Precipitation at pH 4·6 was used to remove residual caseins and to keep macropeptide in solution. In comparison with other methods for determining macropeptide, the present one eliminates the need for pretreatment of samples with trichloroacetic acid (TCA) and allows the recovery of all the macropeptide. Quantitative determination of macropeptide in the 8% TCA-soluble fraction by cation-exchange chromatography showed that only 50–75% of the macropeptide was recovered. This chromatographic technique could also be applied for isolating and producing whole macropeptide on a preparative scale.

scholarly journals The Effect of High-Pressure Treatment and Skimming on Caprine Milk Proteins

2021 ◽  
Vol 11 (13) ◽  
pp. 5982
Author(s):  
Katarzyna Kiełczewska ◽  
Aneta Dąbrowska ◽  
Agnieszka Jankowska ◽  
Maria Wachowska ◽  
Jarosław Kowalik
Keyword(s):  
Protein Solubility ◽  
Whey Proteins ◽  
Color Space ◽  
Skim Milk ◽  
Milk Proteins ◽  
Protein Composition ◽  
Color Difference ◽  
Nitrogen Compounds ◽  
Caprine Milk ◽  
Kjeldahl Method

Background: Proteins are susceptible to HP-treatment and there is a need to determine the applicability of HP-treatment in dairy production. The aim of this study was to determine the effect of HP-treatment at 200–500 MPa (tconst. = 10 min; Tconst. = 20 °C) and skimming of HP-treated milk on the content of nitrogen compounds and protein composition of caprine milk. Methods: The content of nitrogen (total, non-casein, non-protein) was determined using the Kjeldahl method. Casein fractions and whey proteins were separated using SDS-PAGE electrophoresis. Color parameters were measured in the CIELAB color space. Results: HP-treatment decreased (p < 0.05) the content of non-casein nitrogen and soluble whey proteins. Skimming decreased the content of nitrogen compounds, and the noted decrease was more pronounced in HP-treated milk. Pressure and skimming had no influence on the proportions of α-, β-, κ-casein, β-lactoglobulin and α-lactalbumin. Total color difference (ΔE) increased with a rise in pressure, particularly in skim milk. Conclusion: HP-treatment led to a loss of protein solubility at pH 4.6 in caprine milk. In HP-treated milk, skimming did not induce changes in protein composition, despite a decrease in the content of nitrogen compounds after the separation of the cream layer. Higher values of ΔE in skim milk than in whole milk point to changes in colloidal phase components.

Hydrolysis of Milk Proteins by Microbial Enzymes

1980 ◽  
Vol 43 (9) ◽  
pp. 709-712 ◽  
Author(s):  
A. GEBRE-EGZIABHER ◽  
E. S. HUMBERT ◽  
G. BLANKENAGEL
Keyword(s):  
Room Temperature ◽  
Polyacrylamide Gel Electrophoresis ◽  
Whey Proteins ◽  
Skim Milk ◽  
Milk Proteins ◽  
Raw Milk ◽  
Incubation Periods ◽  
Pure Cultures ◽  
Sterilized Milk ◽  
Hydrolysis Of

Raw skim milk was incubated at 7 C for 15 days after inoculation with six psychrotrophic bacterial cultures previously isolated from raw milk. Effects of the microbial activities on proteins of milk were evaluated by polyacrylamide gel electrophoresis. Results showed that all psychrotrophs hydrolyzed milk proteins. The K- and β-caseins were most susceptible to proteolysis while the a-casein was less affected. Most of the isolates required extended incubation periods for hydrolysis of the whey proteins. Commercially sterilized milk samples inoculated with pure cultures developed bitterness after 4 days of storage at 7 C when the psychrotrophic count was 2.5 × 106/ml. The addition of 9.8 enzyme units to UHT milk caused a bitter flavor within 28 days at 7 C and in less than 3 days at room temperature. The presence of only 2 units resulted in bitterness in less than 7 days at room temperature.

Determination of Milk Proteins by Capillary Electrophoresis

1992 ◽  
Vol 75 (5) ◽  
pp. 905-909 ◽  
Author(s):  
Fu-Tai A Chen ◽  
Ji-Hong Zang
Keyword(s):  
Capillary Electrophoresis ◽  
Separation Efficiency ◽  
Whey Proteins ◽  
Milk Proteins ◽  
Fused Silica ◽  
Major Protein ◽  
Fresh Milk ◽  
Dry Milk ◽  
Protein Components

Abstract The potential utility of capillary electrophoresis (CE) for routine determination of milk protein is established. Proteins in cow's milk can be determined by CE in 10 min with high separation efficiency. The major protein components of milk are well-separated and identified. Separations of milk proteins are achieved reliably and reproducibly in an untreated fused-silica column of 21 µm id x 23- 25 cm. Fresh homogenized, low-fat, and nonfat milk show almost identical contents of each protein species; dry milk has a substantially reduced amount of whey proteins, especially oc-lactalbumin. Extensive degradation of whey proteins is evident from a reconstituted dry milk, which may be used to differentiate dry from fresh milk. By using the ratio of β-casein to α-lactalbumin, the adulteration of fresh milk with 25% or more of dry milk could easily be detected.

scholarly journals Effect of Heat Treatment on the Property, Structure, and Aggregation of Skim Milk Proteins

2021 ◽  
Vol 8 ◽  
Author(s):  
Hongbo Li ◽  
Tingting Zhao ◽  
Hongjuan Li ◽  
Jinghua Yu
Keyword(s):  
Secondary Structure ◽  
Disulfide Bonds ◽  
Polyacrylamide Gel Electrophoresis ◽  
Whey Proteins ◽  
Skim Milk ◽  
Milk Proteins ◽  
Surface Hydrophobicity ◽  
Random Coil ◽  
Heat Treated ◽  
Different Temperatures

To study the mechanism of heat-induced protein aggregates, skim milk was heated at 55, 65, 75, 85, and 95°C for 30 s. Then, the sulfhydryl content, surface hydrophobicity, and secondary structure of heat-treated skim milk were studied. Treating skim milk at different temperatures induced a decrease in sulfhydryl content (75.9% at 95°C) and an increase in surface hydrophobicity (44% at 95°C) with a disrupted secondary structure containing random coil, β-sheet, and β-turn of skim milk proteins. The change in these properties facilitated aggregate formation through disulfide bonds and hydrophobicity interaction. Microstructural observation also showed a higher degree of aggregation when skim milk was heated at 85 and 95°C. The result of two-dimensional polyacrylamide gel electrophoresis demonstrated that the aggregates consisted of a high proportion of κ-casein, β-lactoglobulin, and other whey proteins.

Proteins of human milk. I. Identification of major components.

1982 ◽  
Vol 28 (4) ◽  
pp. 1045-1055 ◽  
Author(s):  
N G Anderson ◽  
M T Powers ◽  
S L Tollaksen
Keyword(s):  
Human Milk ◽  
Whey Proteins ◽  
Bovine Milk ◽  
Skim Milk ◽  
Milk Proteins ◽  
Relative Molecular Mass ◽  
Isoelectric Points ◽  
Beta Casein ◽  
Dimensional Electrophoresis ◽  
New Protein

Abstract Traditionally, human milk proteins are identified largely by reference to bovine milk. Hence, to identify the major proteins in human milk, we subjected human and bovine milk, in parallel, to high-resolution two-dimensional electrophoresis. Isoelectric precipitation at pH 4.6 was our criterion for distinguishing whey proteins from those of the casein complex. The alpha- and beta-caseins were identified on the basis of relative abundance, relative molecular mass, and relative isoelectric points. Kappa casein was identified as a series of four spots, which disappear from bovine skim milk treated with rennin (chymosin; EC 3.4.23.4) during the clotting process. Para kappa-casein does not appear on the standard ISO-DALT pattern after treatment of bovine milk with rennin, but does appear in BASO-DALT pattern, indicating its high isoelectric point. No protein disappeared from ISO-DALT patterns of human milk after rennin treatment, and no new protein comparable to bovine para kappa-casein appeared in the BASO-DALT patterns; this suggests that kappa-casein is absent from human milk. The proteins identified in human milk patterns include the alpha and beta casein families, lactalbumin, albumin, transferrin, IgA, and lactoferrin. Numerous additional proteins seen in patterns for human milk remain to be identified.

scholarly journals Post translational modifications of milk proteins in geographically diverse goat breeds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. K. Rout ◽  
M. Verma
Keyword(s):  
Protein Function ◽  
Whey Proteins ◽  
Milk Proteins ◽  
Goat Milk ◽  
Peptide Sequence ◽  
Cow Milk ◽  
Post Translational Modification ◽  
Post Translational Modifications ◽  
Functional Roles ◽  
Dpp Iv

AbstractGoat milk is a source of nutrition in difficult areas and has lesser allerginicity than cow milk. It is leading in the area for nutraceutical formulation and drug development using goat mammary gland as a bioreactor. Post translational modifications of a protein regulate protein function, biological activity, stabilization and interactions. The protein variants of goat milk from 10 breeds were studied for the post translational modifications by combining highly sensitive 2DE and Q-Exactive LC-MS/MS. Here we observed high levels of post translational modifications in 201 peptides of 120 goat milk proteins. The phosphosites observed for CSN2, CSN1S1, CSN1S2, CSN3 were 11P, 13P, 17P and 6P, respectively in 105 casein phosphopeptides. Whey proteins BLG and LALBA showed 19 and 4 phosphosites respectively. Post translational modification was observed in 45 low abundant non-casein milk proteins mainly associated with signal transduction, immune system, developmental biology and metabolism pathways. Pasp is reported for the first time in 47 sites. The rare conserved peptide sequence of (SSSEE) was observed in αS1 and αS2 casein. The functional roles of identified phosphopeptides included anti-microbial, DPP-IV inhibitory, anti-inflammatory and ACE inhibitory. This is first report from tropics, investigating post translational modifications in casein and non-casein goat milk proteins and studies their interactions.

scholarly journals Changes in Particle Size, Sedimentation, and Protein Microstructure of Ultra-High-Temperature Skim Milk Considering Plasmin Concentration and Storage Temperature

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2339
Author(s):  
So-Yul Yun ◽  
Jee-Young Imm
Keyword(s):  
Particle Size ◽  
High Temperature ◽  
Storage Temperature ◽  
Whey Proteins ◽  
Skim Milk ◽  
Storage Period ◽  
Sediment Analysis ◽  
Sediment Formation ◽  
And Storage ◽  
Ultra High Temperature

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks’ storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation.

Influence of dietary proteins on rennin and pepsin content of preruminant calf vell

1974 ◽  
Vol 41 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Pascaline Garnot ◽  
E. Valles ◽  
J.-L. Thapon ◽  
R. Toullec ◽  
R. Tomassone ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Whey Proteins ◽  
Deae Cellulose ◽  
Milk Proteins ◽  
Total Activity ◽  
Separate Experiment ◽  
Dietary Proteins ◽  
Constant Weight ◽  
Cellulose Column ◽  
Qualitative Analyses

SummaryStudies were undertaken to determine the influence of dietary proteins on the rennin and pepsin contents of preruminant calf vell. Three groups of 12 Friesian calves were each fed either milk proteins, whey proteins or a 50:50 mixture of these 2 diets. They were slaughtered at a constant weight of 150kg and their vells collected and dried. Another group of vells was obtained from 8 animals that had been fed milk proteins in a separate experiment. The extraction of the abomasal enzymes was carried out at acid pH, and the extracts were quantitatively analysed for rennin and pepsin by DEAE-cellulose column chromatography. Qualitative analyses were also performed by agarose-acrylamide gel electrophoresis. The only enzymes observed using this last method were rennin and bovine pepsin II. Statistical analysis of the quantitative enzyme determinations indicated a trend for the vells from calves fed diets containing casein to be richer in total activity and in rennin, while the level of pepsin remained approximately constant. It seems that casein may induce the secretion of rennin. However, further experiments will be necessary to confirm this. Important differences were observed between the 2 groups of veils from calves given the same diet, but grown in slightly different conditions.

Determination of Bisphenol A in Milk and Dairy Products by High-Performance Liquid Chromatography with Fluorescence Detection

2003 ◽  
Vol 66 (8) ◽  
pp. 1439-1443 ◽  
Author(s):  
JEONG-HUN KANG ◽  
FUSAO KONDO
Keyword(s):  
Bisphenol A ◽  
Dairy Products ◽  
High Performance ◽  
Solid Phase ◽  
Skim Milk ◽  
The European Union ◽  
Condensed Milk ◽  
Oasis Hlb ◽  
Milk And Dairy Products

This study was conducted to develop a selective and sensitive method for the determination of bisphenol A (BPA) levels in milk and dairy products. A method based on solvent extraction with acetonitrile and solid-phase extraction (SPE) was developed for the analysis of BPA in milk, yogurt, cream, butter, pudding, condensed milk, and flavored milk, and a method using two SPE cartridges (OASIS HLB and Florisil cartridge) for skim milk was also developed. The developed methods showed good recovery levels (77 to 102%) together with low detection limits (1 μg/liter for milk, yogurt, pudding, condensed milk, flavored milk, and skim milk and 3 μg/liter for cream and butter). These methods are simple, sensitive, and suitable for the analysis of BPA in milk and dairy products. When 40 milk and dairy products were analyzed by the proposed methods, BPA was not identified in noncanned products, but its levels ranged from 21 to 43 μg/kg in canned products, levels that were 60- to 140-fold lower than the migration limits in the European Union and Japan.

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