scholarly journals Genetic polymorphism of kappa casein and casein micelle size in the Bulgarian Rhodopean cattle breed

2014 ◽  
Vol 30 (4) ◽  
pp. 561-570 ◽  
Author(s):  
P. Hristov ◽  
B. Neov ◽  
H. Sbirkova ◽  
D. Teofanova ◽  
G. Radoslavov ◽  
...  
Keyword(s):  
Genetic Polymorphism ◽  
Light Scattering ◽  
Cattle Breed ◽  
Cow Milk ◽  
Casein Micelle ◽  
Technological Properties ◽  
Casein Micelles ◽  
Milk Samples ◽  
Micelle Size

The present study aimed to compare the size of casein micelle in cow milk sample in function of kappa casein (CSN3) genetic polymorphism. Sixteen cows from Bulgarian Rhodopean cattle breed were genotyped by PCRRFLP analysis. Milk samples from the three found CSN3 genotypes (AB, AA and BB) were employed for the determination of casein micelles size by Dynamic Light Scattering (DLS). The results showed differences in the size and polydispersity of the casein micelles between the milks of cows with different genotypes. Hydrodynamic radii of micelles at a scattering angle of 90?C varied from 80 to 120 nm and polydispersity varied from 0.15 to 0.37. In conclusion casein micelle size of CSN3 AA cows (~ 120 nm) exceed with about 60% cows with (~ 80 nm) and BB genotype (~ 70 nm). These results could be useful for improving technological properties of the milk.

The structure of casein micelles between pH 5·5 and 6·7 as determined by light-scattering, electron microscopy and voluminosity experiments

1989 ◽  
Vol 56 (3) ◽  
pp. 463-470 ◽  
Author(s):  
Henk J. Vreeman ◽  
Bas W. van Markwijk ◽  
Paula Both
Keyword(s):  
Electron Microscopy ◽  
Light Scattering ◽  
Comparative Data ◽  
Casein Micelle ◽  
Protein Matrix ◽  
Casein Micelles ◽  
Inelastic Light Scattering ◽  
Micelle Size

SummaryHydrodynamic radii from inelastic light-scattering experiments and radii of gyration from Zimm plots give an indication of the change of average casein micelle size when the pH is changed. Combination of the results of both types of measurements gives information on changes in the micelle protein matrix, i.e. changes in the voluminosity.The voluminosity was also determined by the pellet method and by electron microscopy which also provided comparative data on size parameters.

scholarly journals A Fast and Efficient Ultrasound-Assisted Extraction of Tocopherols in Cow Milk Followed by HPLC Determination

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4645
Author(s):  
Archimede Rotondo ◽  
Giovanna Loredana La Torre ◽  
Teresa Gervasi ◽  
Giacomo di Matteo ◽  
Mattia Spano ◽  
...  
Keyword(s):  
Cattle Breed ◽  
Hplc Method ◽  
Cow Milk ◽  
Ultrasound Assisted Extraction ◽  
Fluorescence Detector ◽  
Milk Samples ◽  
Assisted Extraction ◽  
Relative Standard ◽  
Ultrasound Assisted

A fast HPLC method with fluorescence detector (FD) was developed for the determination of three tocopherols (TOCs) in milk samples from Modicana cattle breed. The ultrasound-assisted procedure was optimized for the extraction of TOCs prior to HPLC/FD analysis, reducing sample preparation time and allowing a fast quantification of α-tocopherol, δ-tocopherol and γ tocopherol. The optimized ultrasonic extraction combines an efficient and simple saponification at room temperature and a rapid HPLC quantification of TOCs in milk. The precision of the full analytical procedure was satisfactory and the recoveries at three spiked levels were between 95.3% and 87.8%. The linear correlations were evaluated (R2 > 0.99) and the relative standard deviation (RSD) values for intra-day and inter-day tests at three spiked levels were below 1% for the retention time and below 5.20% for the area at low level spiking. The proposed procedure, reducing the experimental complexity, allowed accurate extraction and detection of three TOCs in milk samples from Modicana cattle breed.

Hydrophobic interactions in human casein micelle formation: β-casein aggregation

1989 ◽  
Vol 56 (3) ◽  
pp. 427-433 ◽  
Author(s):  
Charles W. Slattery ◽  
Satish M. Sood ◽  
Pat Chang
Keyword(s):  
Light Scattering ◽  
Conformational Transition ◽  
Hydrophobic Interactions ◽  
Micelle Formation ◽  
Tryptophan Fluorescence ◽  
Phosphate Esters ◽  
Casein Micelle ◽  
Protein Association ◽  
P Protein ◽  
Micelle Size

SummaryThe association of non-phosphorylated (0-P) and fully phosphorylated (5-P) human β-caseins was studied by fluorescence spectroscopy and laser light scattering. The tryptophan fluorescence intensity (FI) level increased between 20 and 35 °C, indicating a change in the environment of that residue. A similar transition occurred when ANS was used as a probe. Transition temperatures were slightly lower in 10 mM-CaCl2 but were not affected by an equivalent increase in ionic strength caused by NaCl. The magnitude of the FI change was less for the 5-P than the 0-P protein but was increased for both by CaCl2 addition. These FI data were characteristic of a conformational change and this was supported by fluorescence polarization which indicated that with CaCl2, tryptophan and ANS mobility increased at the transition temperature even though the extent of protein association also increased. Light scattering suggested that protein association proeeeded with the primary formation of submicellar aggregates containing 20–30 monomers which then associated further to form particles of minimum micelle size (12–15 submicelles), and eventually larger. The temperature of precipitation of the 5-P form in the presence of CaCl2 was lower than the conformational transition and suggested that both hydrophobic interactions and Ca bridges between phosphate esters on adjacent molecules are important in micelle formation.

scholarly journals Association of casein micelle size and enzymatic curd strength and dry matter curd yield

2019 ◽  
Vol 49 (3) ◽  
Author(s):  
Denise Ribeiro de Freitas ◽  
Fernando Nogueira de Souza ◽  
Jamil Silvano de Oliveira ◽  
Diêgo dos Santos Ferreira ◽  
Cristiane Viana Guimarães Ladeira ◽  
...  
Keyword(s):  
Fixed Effects ◽  
Dry Matter ◽  
Linear Models ◽  
Favorable Effect ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Micelle Size ◽  
Milk Protein Content ◽  
Bulk Tank ◽  
Cheese Production

ABSTRACT: The aim of the present study was to explore the association between milk protein content and casein micelle size and to examine the effects of casein micelle size on enzymatic curd strength and dry matter curd yield using reduced laboratory-scale cheese production. In this research, 140 bulk tank milk samples were collected at dairy farms. The traits were analyzed using two linear models, including only fixed effects. Smaller micelles were associated with higher κ-casein and lower αs-casein contents. The casein micellar size (in the absence of the αs-casein and κ-casein effects) did not affect the enzymatic curd strength; however, smaller casein micelles combined with higher fat, lactose, casein and κ-casein contents exhibited a favorable effect on the dry matter curd yield. Overall, results of the present study provide new insights into the importance of casein micelle size for optimizing cheese production.

Effect of the A and B variants of both αs1- and κ-casein on bovine casein micelle solvation and κ-casein content

1993 ◽  
Vol 60 (4) ◽  
pp. 505-516 ◽  
Author(s):  
Skelte G. Anema ◽  
Lawrence K. Creamer
Keyword(s):  
Genetic Variants ◽  
The Other ◽  
Casein Micelle ◽  
Lactation Period ◽  
Chromosomal Dna ◽  
Electrophoretic Method ◽  
Milk Samples ◽  
Micelle Size ◽  
Centrifugation Technique ◽  
Β Lactoglobulin

SummaryCasein micelle solvation, a micelle characteristic that is sensitive to many factors, has been measured by a centrifugation technique at 30 °C for a series of uncooled fresh skim milks at pH 6·3, 6·6, 6·9 and 7·1. The relative αs-(αs1- plus αs2-), β– and κ-casein contents of all centrifuge pellets and supernatants were determined by a standardized electrophoretic method. The calcium and phosphate contents of a number of the pellets and milk samples were also determined. Solvation of micelles from milks with various genetic variants of β-lactoglobulin (A and B), αs1-casein (A and B) and κ-casein (A and B) was often found to be lower for milks containing either the B variant of αs1-casein or the A variant of κ-casein. It was also found that these two variant caseins were associated with a lower κ-casein content of the milks and the micelles, which is consistent with the lower solvation as κ-casein is associated with smaller micelle size and greater solvation. The solvations also seemed to increase during the lactation period. It is possible that some of the other features of milk and its products that have been ascribed to the differences in functional character between the A and B variants of αs1-casein may be partly caused by the increased level of κ-casein. The reason for the association of the A variant of αs1-casein with higher concentrations of κ-casein (and micelle solvation) is not obvious but possibly the haplotype αs1-casein A, β-casein A1, κ-casein A contains a controlling sequence in the chromosomal DNA that enhances expression of the κ-casein gene.

Influence of homogenization of concentrated milks on the structure and properties of rennet curds

1983 ◽  
Vol 50 (3) ◽  
pp. 341-348 ◽  
Author(s):  
Margaret L. Green ◽  
Richard J. Marshall ◽  
Frank A. Glover
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Size Distribution ◽  
Casein Micelle ◽  
Structure And Properties ◽  
Moisture Retention ◽  
Casein Micelles ◽  
Micelle Size ◽  
Whole Milk ◽  
Milk Casein

SummaryWhole milk was concentrated by ultrafiltration in a plant causing some homogenization of the fat. Comparisons were made with milk concentrated in a plant causing little homogenization and with milk homogenized conventionally. None of the processes appreciably affected the casein micelle size distribution. On rennet treatment of homogenized milk, casein micelle aggregation occurred more slowly, the protein network in the curd was less coarse and the rate of whey loss was reduced, compared with non-homogenized milk at the same concentration. In using concentrated milks for cheesemaking homogenization improved the composition of Cheddar cheese, because of increased fat and moisture retention, but curd fusion was poorer. Some aspects of the texture of the mature cheeses were improved, but the free fatty acid levels were higher. Values for the firmness of curds, formed from milks processed in different ways, did not relate to the extent of aggregation of the casein micelles. It is suggested that the complete cheesemaking process is driven by the tendency of the casein to aggregate.

scholarly journals Determination of Ultratrace Bismuth in Milk Samples by Atomic Fluorescence Spectrometry

2003 ◽  
Vol 86 (4) ◽  
pp. 815-822 ◽  
Author(s):  
Patricia Cava-Montesinos ◽  
M Luisa Cervera ◽  
Agustín Pastor ◽  
Miguel de la Guardia
Keyword(s):  
Inductively Coupled Plasma ◽  
Limit Of Detection ◽  
Hydride Generation ◽  
Fluorescence Spectrometry ◽  
Cow Milk ◽  
Atomic Fluorescence Spectrometry ◽  
Atomic Fluorescence ◽  
Microwave Assisted ◽  
Milk Samples

Abstract A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG–AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8–28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma–mass spectrometry after microwave-assisted digestion.

A Vapor Pressure Osmometer for Determination of Added Water in Milk

1975 ◽  
Vol 38 (4) ◽  
pp. 204-207 ◽  
Author(s):  
K. PENSIRIPUN ◽  
E. C. CAMPBELL ◽  
G. H. RICHARDSON
Keyword(s):  
Vapor Pressure ◽  
Collaborative Study ◽  
Raw Milk ◽  
Cow Milk ◽  
Filter Paper Disc ◽  
Milk Samples ◽  
Added Water ◽  
Sample Chamber ◽  
Paper Disc

A vapor pressure osmometer requiring a 5- to 7-microliter sample to saturate a 0.64 cm filter paper disc fixed a digital readout of milliosmolality in 110 sec. A coefficient of variability of 0.70 was obtained on a raw milk sample tested 25 times when an acetone impregnated tissue was used to clean the sample chamber between tests. Two hundred individual cow milk samples from 20 herds averaged 280.0 ± 3.0 milliosmols. Milk samples containing up to 25% added water were evaluated on both the vapor pressure osmometer and a thermistor cryoscope with a resultant correlation coefficient of 0.991. A collaborative study involving eight hospital and industry laboratories was conducted. When the results of two laboratories were discarded, due to instrument maintenance problems, there were no significant differences among the laboratories in their abilities to quantitate added water in milk.

High pressure treatment of bovine milk: effects on casein micelles and whey proteins

2004 ◽  
Vol 71 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Thom Huppertz ◽  
Patrick F Fox ◽  
Alan L Kelly
Keyword(s):  
High Pressure ◽  
Treatment Time ◽  
Whey Proteins ◽  
Bovine Milk ◽  
Casein Micelle ◽  
Pressure Treatment ◽  
Casein Micelles ◽  
High Pressure Treatment ◽  
Micelle Size ◽  
Β Lactoglobulin

Effects of high pressure (HP) on average casein micelle size and denaturation of α-lactalbumin (α-la) and β-lactoglobulin (β-lg) in raw skim bovine milk were studied over a range of conditions. Micelle size was not influenced by treatment at pressures <200 MPa, but treatment at 250 MPa increased micelle size by ∼25%, while treatment at [ges ]300 MPa irreversibly reduced it to ∼50% of that in untreated milk. The increase in micelle size after treatment at 250 MPa was greater with increasing treatment time and temperature and milk pH. Treatment times [ges ]2 min at 400 MPa resulted in similar levels of micelle disruption, but increasing milk pH to 7·0 partially stabilised micelles against HP-induced disruption. Denaturation of α-la did not occur [les ]400 MPa, whereas β-lg was denatured at pressures >100 MPa. Denaturation of α-la and β-lg increased with increasing pressure, treatment time and temperature and milk pH. The majority of denatured β-lg was apparently associated with casein micelles. These effects of HP on casein micelles and whey proteins in milk may have significant implications for properties of products made from HP-treated milk.

Sign in / Sign up

Export Citation Format

Share Document