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The Casein-IEF Consumable Kit
Adulteration of sheep and goat milk cheese by addition of cows' milk is reliably detected by isoelectric focusing of enzymatically modified caseins [1]. According to the hydrophobic nature of the caseins, focusing must be performed in the presence of 7 M Urea. To avoid laborious and hazardous casting of the urea-containing gels which have a limited shelf-life due to urea decomposition, CleanGels ready to use rehydratable gels are preferably used.
For the special demand of species identification in milk, cheese and other dairy products via high-resolution electrophoretic separation of caseins, the CleanGels IEF Ultra and the Casein-IEF Consumables Kit were developed in cooperation with Ingolf Krause of the TU München-Weihenstephan, advising author of the European Reference Method [1] and the German Official Method [2].
This Kit may also be applied for the detection and determination (by densitometry) of casein in food and feedingstuff.
This kit includes:
Special Ampholyte IEF-cocktail for 5 CleanGels Ultra. 5 Test-tubes containing portioned urea. 3 ml Sample-Colour (10x). 5 Drying Cardboards. 5 Preserving sheets. Manuals: “Casein-IEF Consumables Kit ETC 1004-06“ and „Detection of Cows' Milk in Ewes' and Goats' Milk Cheese in the Presence of Urea with CleanGel IEF Ultra“.
IEF of plasminolyzed caseins from different cheeses and standards. Samples and run by I. Krause/I. Sperrer, Protein Analysis Group, ZIEL, TUM-Weihenstephan, Germany
The bands gamma 1,2 and 3 (marked * at read-out position) are used to specifically detect cow-caseins in ewes' and goats'milk cheese. CRM 599 = certified reference material of casein curd [3] with 0% and 1% cow's milk, respectively (available from IRMM, B-2440 Geel, Belgium)
- [1] REFERENCE METHOD FOR THE DETECTION OF COWS' MILK AND CASEINATE IN CHEESES FROM EWES' MILK, GOATS' MILK OR BUFFALOS' MILK OR MIXTURES OF EWES', GOATS' AND BUFFALOS' MILK. COMMISSION REGULATION (EC) No 213/2001 of 9 January 2001, Annex XV to Article 10. Official Journal of the European Communities, Nr. L37 of 07.02.2001; pp. 51-59
- [2] Nachweis der Tierart bei Milch, Milchprodukten und Käse mit Hilfe der isoelektrischen Fokussierung (PAGIF); Amtliche Sammlung von Untersuchungsverfahren nach §35 LMBG, Methode L01.00-39 (1995)
- [3] The certification of two reference materials to be used for the detection of cows' milk casein in cheeses from ewes' milk, goats' milk and mixtures of ewes' and goats' milk. bcr information REFERENCE MATERIALS. Report EUR 17254 EN (1996)
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