Effect of Method of Preparation on Composition and Electrophoretic Properties of lsoelectric Casein

Kim, G.; Bird, E.W.

doi:10.3168/jds.s0022-0302(72)85594-2

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…15 Starch gel electrophoresis containing 7M urea was used to separate the three chemically different fractions of caseins: α s -(calcium sensitive), β-(calcium non-sensitive) and k-casein (calcium non-sensitive glycoprotein). 16 The relative proportion of each fraction was determined using a Gelman ACD-15 densitometer adjusted to 595 nm.…”

Section: Laboratory Analyses To Obtain Reference Values For Calibrationmentioning

confidence: 99%

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose

Díaz-Carrillo

Muñoz-Serrano

Alonso-Moraga

et al. 1993

Journal of Near Infrared Spectroscopy

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A fast and inexpensive method to quantify the main constituents of goat's milk using near infrared (NIR) spectroscopy, is proposed. Since the efficiency of milk-to-cheese transformation depends on the total amount of casein, as well as on the relative proportions of the different types of caseins, it is desirable to quantify not only protein, fat and lactose, as is normally done routinely in the cheese industry and milk recording schemes, but also total casein, α s -, βand k-caseins. Quantities of these main components have been measured in milk samples of three Spanish breeds of goats, using traditional chemical, electrophoretical and densitometric laboratory methods in order to produce NIR calibrations for total protein, total casein, casein fractions (α s -, βand k-caseins), fat and lactose. Low standard errors and high coefficients of determinations have been obtained for the calibrations and validations. Goat's milk spectra are described, and the contribution of different components to the observed pattern is discussed. Due to the low cost, facility and rapidity of the analyses after the spectrophotometer has been calibrated for each milk component, the use of near infrared spectroscopy becomes a suitable tool to analyse large numbers of samples and, therefore, very suitable for dairy goat recording schemes.

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Section: Laboratory Analyses To Obtain Reference Values For Calibrationmentioning

confidence: 99%

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose

Díaz-Carrillo

Muñoz-Serrano

Alonso-Moraga

et al. 1993

Journal of Near Infrared Spectroscopy

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“…Casein was also prepared from raw skim-milk by precipitation with 0-5 N-HC1 according to the method of Kim & Bird (1972) and individual components of casein prepared as described by Andrews & Cheeseman (1971).…”

Section: Milk Fractionationmentioning

confidence: 99%

The role of various milk fractions and the importance of somatic cells in the formation of germinant(s) for Bacillus cereus when milk is pasteurized

Davies¹

1977

Journal of Dairy Research

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Confirmation was obtained for the occurrence of an interaction between high and low molecular weight fractions of milk during its pasteurization, resulting in the formation of germinant(s) for Bacillus cereus. Various milk fractions were added to supernatants or dialysates of raw skim-milk, pasteurized and assayed for germinant. Micellar casein obtained by high speed centrifugation of raw milk stimulated germinant formation, but whole casein obtained by acid precipitation was less stimulatory and individual casein fractions showed no stimulation. A membrane rich 'fluff' layer obtained by high speed centrifugation of raw milk was highly stimulatory and suggested the possibility that the somatic cell count of milk may be related to germinant production.Using milk from endotoxin infused and infected quarters of individual cows, a correlation between cell count and germinant formation was clearly demonstrated. Adjustment of the cell counts of individual milk samples was generally accompanied by corresponding changes in germinant formation, though removal of cells by filtration did not have this effect, possibly since germinant precursor had leached from the cells and remained in the milk. Pasteurization was necessary, not simply to express germinant from cells but to effect an interaction of germinant precursors. It is not clear whether the cell associated germinant precursor is derived from the cells themselves or from a related component. Addition of blood serum proteins was without stimulatory effect.Since low cell count milks sometimes supported appreciable germination after pasteurization, but showed still higher levels when the cell count was raised, germinant may be formed via 2 pasteurization dependent processes, one between milk constituents alone and the other involving both milk constituents and somatic cells.Studies in this laboratory have shown that when bovine milk is pasteurized, a germinant for spores of Bacillus cereus is produced (Wilkinson & Davies, 1973, 1974. Our attempts to identify this germinant have not yet been successful, though we have established that it is a compound of low molecular weight (probably below 200) and is not one of the amino-acids or ribosides known to induce germination of 36 DAR44

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“…Identification of the genetic variants was performed by starch gel electrophoresis at alkaline pH (Kim and Bird, 1972 …”

Section: Methodsmentioning

confidence: 99%

Genetic polymorphism of milk protein loci in Argentinian Holstein cattle

2000

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Some alleles of milk protein loci are associated with superior cheese production characteristics. The genetic polymorphism of the milk protein loci alphas1-casein, beta-casein, k-casein and beta-lactoglobulin was examined in Argentinian Holstein cattle. Samples from 12 herds of four regions of Córdoba were analyzed by starch gel electrophoresis. The chi² test was used to assess whether the populations were in Hardy-Weinberg equilibrium. Genotypic diversity was analyzed by the Shannon-Weaver index. The observed genotypic frequencies were analyzed by Hedrick's genetic identity and the genetic distance of Balakrishnan and Sanghvi. The allelic and genotypic frequencies were similar to those of other Holstein populations. The genotypic frequencies of the alphas1-casein and beta-casein loci were in equilibrium, whereas in some populations the k-casein and beta-lactoglobulin loci were not. According to the Shannon-Weaver index the total genetic diversity within each herd was greater than 96%. The high values of identity agreed with the low genetic distances among populations. We conclude that there is extensive genetic homogeneity in Holstein cattle in Córdoba Province and that it would be feasible to select for B alleles at the k-casein and b-lactoglobulin loci in order to improve the quality of milk available for cheese manufacturing.

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Effect of Method of Preparation on Composition and Electrophoretic Properties of lsoelectric Casein

Cited by 5 publications

References 30 publications

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose

The role of various milk fractions and the importance of somatic cells in the formation of germinant(s) for Bacillus cereus when milk is pasteurized

Genetic polymorphism of milk protein loci in Argentinian Holstein cattle

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Effect of Method of Preparation on Composition and Electrophoretic Properties of lsoelectric Casein

Cited by 5 publications

References 30 publications

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, αs-, β- and k-caseins, Fat and Lactose

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, αs-, β- and k-caseins, Fat and Lactose

The role of various milk fractions and the importance of somatic cells in the formation of germinant(s) for Bacillus cereus when milk is pasteurized

Genetic polymorphism of milk protein loci in Argentinian Holstein cattle

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Product

Resources

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Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose

Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, α_s-, β- and k-caseins, Fat and Lactose