Quantification of alpha s1-casein in goat milk from French-Alpine and Anglo-Nubian breeds using reversed-phase high performance liquid chromatography.
Samples of isoelectrically precipitated goat casein from the milks of French-Alpine and Anglo-Nubian breeds were separated into four components in a single run by reversed-phase HPLC. The proportion of alpha s1-casein thus resolved was determined quantitatively. The method uses a reversed-phase C-4 column and a linear gradient from 30 to 50% acetonitrile in 30 min with trifluoroacetic acid constant at .1%. Sodium dodecyl sulfate-PAGE was carried out to establish the identity of the isolated components. By a comparison with previously published results for caprine and bovine milk caseins, the four peaks were identified as kappa-, alpha s2-, alpha s1-, and beta-casein. Quantitative variations in the chromatographically resolved alpha s1-casein fraction of goat milk were evident. Some individual goat milks contained high levels of alpha s1-casein (2.70 g/L), but others contained significantly low levels (.12 g/L). There was no statistical difference in the overall means between breeds in alpha s1-casein composition, but cluster analysis statistics showed three distinct categories of alpha s1-producers: high, medium, and low. Interestingly, 6 of 15 French-Alpine goats and only one Anglo-Nubian goat fell into the "low" producer category (.38 +/- .2 g/L). Thus, expression of the alpha s1-component may be genetically regulated but may not be a breed-specific trait.
Mora-Gutierrez
A
A
Cooperative Agricultural Research Center, Prairie View A&M University, TX 77448.
Kumosinski
T F
TF
Farrell
H M
HM
D000818:Animals; D001947:Breeding; D002364:Caseins / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006041:Goats / Q000235:genetics / Q000502:physiology*; D007774:Lactation / Q000235:genetics*; D008892:Milk / Q000032:analysis*
D002364:Caseins