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.

Effect of heat treatment on casein micelle profiles obtained by controlled pore-glass chromatography

1986 ◽  
Vol 53 (4) ◽  
pp. 585-593 ◽  
Author(s):  
Malcolm Anderson ◽  
Carolyn Moore ◽  
Mary C. A. Griffin
Keyword(s):  
Heat Treatment ◽  
Correlation Spectroscopy ◽  
Holding Time ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Photon Correlation ◽  
Controlled Pore Glass ◽  
Micelle Size ◽  
Whole Milk ◽  
Pore Glass

SummaryThe effect of heat treatment on the profiles of casein micelles obtained at 340 and 280 nm from controlled pore-glass chromatography of milk was studied in a series of unhomogenized whole milk samples which had been heated in a pilot plant at 75, 90, 105, 120, 135 and 150 °C for holding times of 4, 16, 32, 72, 150 and 300 s. A second experiment was carried out in which whole milk was preheated at temperatures between 70 and 110 °C for 13, 60 and 180 s before being treated at 120 °C for 4 s or 150 °C for 16 s. The average micelle size in some of the samples was determined by photon correlation spectroscopy. Profiles were divided into four fractions in which micelle size decreased from fraction 1 to fraction 4. The dimensions of these fractions were expressed in terms of size relative to that of the total profile. Fraction 4 was not affected by any of the heat treatments. Fractions 1–3 were significantly affected only by temperatures above 120 °C. Between 120 and 150 °C fraction 1 increased significantly while fractions 2 and 3 showed a corresponding decrease. Holding time affected fraction 1 only above 120 °C. For fraction 2 there was no effect in < 32 s at temperatures less than 150 °C. Fraction 3 was the most sensitive to changes in holding time, but no effect was observed below 105 °C. Average micelle size measurements indicated that a substantial size increase only occurred in those milks heated at 135 °C for longer than 16 s and in all the samples at 150 °C. To assess whether this increase in micelle size was reversible, samples were dialysed against a 70 mm-NaCl solution containing 10 mm-EDTA and then separated by column chromatography on Sephacryl S-300. The proportion of materials which was undissociated by dialysis remained unchanged for temperatures below 120 °C, but progressively increased with treatments more severe than 120 °C for 16 s. Column profiles were not influenced by variations in the conditions of preheating

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.

Inelastic light-scattering study of the size distribution of bovine milk casein micelles

Biochemistry ◽  
1971 ◽  
Vol 10 (25) ◽  
pp. 4788-4793 ◽  
Author(s):  
S. H. C. Lin ◽  
R. K. Dewan ◽  
V. A. Bloomfield ◽  
C. V. Morr
Keyword(s):  
Light Scattering ◽  
Size Distribution ◽  
Bovine Milk ◽  
Casein Micelles ◽  
Inelastic Light Scattering ◽  
Scattering Study ◽  
Milk Casein

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.

High-pressure treatment of milk: effects on casein micelle structure and on enzymic coagulation

2000 ◽  
Vol 67 (1) ◽  
pp. 31-42 ◽  
Author(s):  
ERIC C. NEEDS ◽  
ROBERT A. STENNING ◽  
ALISON L. GILL ◽  
VICTORIA FERRAGUT ◽  
GILLIAN T. RICH
Keyword(s):  
Whey Proteins ◽  
Skim Milk ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Dense Networks ◽  
Protein Levels ◽  
Micelle Structure ◽  
Milk Casein ◽  
Β Lactoglobulin ◽  
Gel Network

High isostatic pressures up to 600 MPa were applied to samples of skim milk before addition of rennet and preparation of cheese curds. Electron microscopy revealed the structure of rennet gels produced from pressure-treated milks. These contained dense networks of fine strands, which were continuous over much bigger distances than in gels produced from untreated milk, where the strands were coarser with large interstitial spaces. Alterations in gel network structure gave rise to differences in rheology with much higher values for the storage moduli in the pressure-treated milk gels. The rate of gel formation and the water retention within the gel matrix were also affected by the processing of the milk. Casein micelles were disrupted by pressure and disruption appeared to be complete at treatments of 400 MPa and above. Whey proteins, particularly β-lactoglobulin, were progressively denatured as increasing pressure was applied, and the denatured β-lactoglobulin was incorporated into the rennet gels. Pressure-treated micelles were coagulated rapidly by rennet, but the presence of denatured β-lactoglobulin interfered with the secondary aggregation phase and reduced the overall rate of coagulation. Syneresis from the curds was significantly reduced following treatment of the milk at 600 MPa, probably owing to the effects of a finer gel network and increased inclusion of whey protein. Levels of syneresis were more similar to control samples when the milk was treated at 400 MPa or less.

scholarly journals Effect of Ultrafiltration of Skim Milk on Casein Micelle Size Distribution in Retentate

1991 ◽  
Vol 74 (1) ◽  
pp. 50-57 ◽  
Author(s):  
S. Srilaorkul ◽  
L. Ozimek ◽  
B. Ooraikul ◽  
D. Hadziyev ◽  
F. Wolfe
Keyword(s):  
Size Distribution ◽  
Skim Milk ◽  
Casein Micelle ◽  
Micelle Size

Molecular weight and size distribution of bovine milk casein micelles

1974 ◽  
Vol 342 (2) ◽  
pp. 313-321 ◽  
Author(s):  
R.K. Dewan ◽  
A. Chudgar ◽  
R. Mead ◽  
V.A. Bloomfield ◽  
C.V. Morr
Keyword(s):  
Molecular Weight ◽  
Size Distribution ◽  
Bovine Milk ◽  
Casein Micelles ◽  
Milk Casein

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.

Effects of high pressure on some constituents and properties of buffalo milk

2005 ◽  
Vol 72 (2) ◽  
pp. 226-233 ◽  
Author(s):  
Thom Huppertz ◽  
Mathias R Zobrist ◽  
Therese Uniacke ◽  
Vivekk Upadhyat ◽  
Patrick F Fox ◽  
...  
Keyword(s):  
High Pressure ◽  
Buffalo Milk ◽  
Casein Micelle ◽  
Coagulation Time ◽  
Casein Micelles ◽  
Rennet Coagulation ◽  
Micelle Size ◽  
Significant Difference ◽  
Β Lactoglobulin

In this study, effects of high pressure (HP) on some constituents and properties of buffalo milk were examined. HP treatment at 100–600 MPa for 30 min affected casein micelle size only slightly, whereas treatment at 800 MPa increased it by ~35%. Levels of non-micellar αs1- and β-caseins were increased by treatment [ges ]250 MPa, and were highest after treatment at 400–800 MPa. The level of non-micellar calcium increased with increasing pressure up to 600 MPa. The L*-value of the milk decreased gradually with increasing pressure, from ~82 for untreated milk to ~65 for milk treated at 800 MPa. Milk pH was increased by ~0·07 units after treatment at 100–800 MPa, with no significant difference between treatment pressures. Denaturation of α-lactalbumin occurred at pressures [ges ]400 MPa, and reached >90% after treatment at 800 MPa, whereas β-lactoglobulin (β-lg) was denatured >100 MPa, reaching ~100% after treatment at 400 MPa; after treatment [ges ]400 MPa, all β-lg was associated with the casein micelles. The rennet coagulation time of buffalo milk increased with increasing pressure, whereas the strength of the coagulum formed decreased after treatment at 250–800 MPa. Overall, HP treatment affected many constituents and properties of buffalo milk; some of these effects have also been observed in the milk from other species, but the extent of the effects, and the pressure at which they occurred, differed considerably.

Electrophoretic mobility of casein micelles

1979 ◽  
Vol 46 (3) ◽  
pp. 441-451 ◽  
Author(s):  
Donald F. Darling ◽  
John Dickson
Keyword(s):  
Electrophoretic Mobility ◽  
Moving Boundary ◽  
Ionic Composition ◽  
Skim Milk ◽  
Casein Micelle ◽  
Casein Micelles ◽  
Zeta Potentials ◽  
Micelle Structure ◽  
Increase With Increase ◽  
Micelle Size

SummaryA simplified moving boundary electrophoresis technique has been developed for the measurement of the electrophoretic mobility of casein micelles. The zeta potentials of casein micelles from different skim-milk samples were calculated using Henry's equation and shown to decrease with decrease in pH between pH 6.9 and 5.3 and to increase with increase in temperature between 10 and 45 °C. Neither severe heat treatment (up to 135 °C for 51 min) nor centrifugal fractionation of micelles into different micelle size ranges had any significant effect on zeta potential. The ionic composition of the serum phase has been shown to be extremely important in determining the electrophoretic mobility. Casein micelles electrophoresed through milk ultrafiltrate consistently gave a lower mobilities than the same micelles centrifuged through milk centrifugate. The results are discussed in relation to present theories of casein micelle structure; these theories do not accommodate all of the observations.

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