Detection of Adulteration of Buttermilk Powder by Gel Electrophoresis

Six commercial samples sold as buttermilk powder were compared with an authentic sample by SDS-PAGE, using either large gels (13.5 × 18 × .3cm) with a manual system or precast miniature gels (4.3 × 5.0 × .045cm) with an automated system. After being stained with Coomassie blue R, protein bands were...

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Bibliographic Details
Published in:Journal of dairy science 1994-08, Vol.77 (8), p.2199-2206
Main Authors: Malin, Edyth L., Basch, Jay J., Shieh, James J., Sullivan, Brien C., Holsinger, Virginia H.
Format: Article
Language:English
Subjects:
ADULTERACION
ADULTERATION
BABEURRE
Biological and medical sciences
buttermilk powder
ELECTROFORESIS
ELECTROPHORESE
fat globule membrane proteins
Food industries
Fundamental and applied biological sciences. Psychology
GLOBULE GRAS
GLOMERULOS DE GRASA
LAIT DESHYDRATE
LECHE EN POLVO
Milk and cheese industries. Ice creams
nonfat dry milk
PRODUCTOS LACTEOS
PRODUIT LAITIER
SUERO DE LECHE
whey
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Summary:Six commercial samples sold as buttermilk powder were compared with an authentic sample by SDS-PAGE, using either large gels (13.5 × 18 × .3cm) with a manual system or precast miniature gels (4.3 × 5.0 × .045cm) with an automated system. After being stained with Coomassie blue R, protein bands were quantitated by densitometry. Two unique fat globule membrane proteins, in addition to the caseins and whey proteins, were clearly visible in authentic buttermilk powders, but densities of fat globule membranes were reduced or absent in commercial nonfat dry milk and adulterated powders. The extent of adulteration was estimated by comparison of the relative percentage of fat globule membrane proteins in a suspect sample with their percentage in an authentic sample. The limit of detection for significant fat globule membrane protein bands was 12μg of a 229-μg sample applied to a large gel and 420ng of a 5-μg sample on a miniature gel. Although large gels facilitated visual observation of results, several days were required to cast a gel, separate the proteins, stain, and destain. In contrast, SDS-PAGE on miniature gels with the automated system required less than 3h and offered a rapid screening procedure for detection of adulterated buttermilk powders.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(94)77162-9