[The quantitative determination of protein content in milk by means of ultraviolet spectrophotometry. 2. The suitability of the difference of absorbance at 235 and 280 nm for quantitative milk protein analysis].
The protein content of skimmed milk was determined by measuring the absorbance at 235 and 280 nm after dilution with alkylpolyglycolethersulphate solution. The difference of absorbance A235-A280 shows a high correlation to the values of KJELDAHL nitrogen analysis (r = 0.99). The protein content of casein and milkserum solutions could be determined in the same way. The method has the advantage, that their results are approximately independent of the amino acid composition of proteins, the content of nucleic acids, salts, lactose and non protein nitrogen. Both absorbances are obtainable from one solution. The dependence of the absorbance difference from the age of solution, the age of milk and from the temperature was investigated as well as the influence of preservatives.
D000818:Animals; D002417:Cattle; D008892:Milk / Q000032:analysis*; D008894:Milk Proteins / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
D008894:Milk Proteins
Die quantitative Bestimmung des Proteingehaltes der Milch mittels Ultraviolettspektralphotometrie. 2. Mitt. Zur Eignung der Differenz der Absorbanzwerte bei 235 und 280 nm für die quantitative Milchproteinanalytik.