title: Quantitative ¹H NMR analysis of egg yolk, alcohol, and total sugar content in egg liqueurs.
abstract: Analyzing egg liqueurs for compliance with legal requirements means several different time-consuming preparations and analytical processes. In this paper, we describe the approach to use quantitative (1)H NMR spectroscopy as an accurate alternative technique. (1)H NMR analysis comprised two different rapid sample preparations for water-soluble or nonpolar ingredients. Fifteen egg liqueurs were analyzed for alcoholic strength and content of total sugar and egg yolk (estimated by cholesterol as a marker substance) with both classical methods and quantitative (1)H NMR spectroscopy. The results of both methods showed excellent correlations for alcoholic strength (R = 0.996, p < 0.001) and content of total sugar (R = 0.989, p < 0.001) and cholesterol (R = 0.995, p < 0.001). Besides, NMR spectra revealed further information: a signal of phosphatidylcholine at about δ = 3.20 ppm served as a second marker for the egg yolk content, and characteristic signals of lactose at δ = 4.46 ppm and butyric acid at δ = 0.97 ppm indicated the use of milk products, which has to be declared for lactose-intolerant consumers.
authors: †Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.|‡Bavarian Health and Food Safety Authority, Luitpoldstraße 1, 97082 Würzburg, Germany.
authors: Monika
authors: M
authors: Hohmann
authors: ‡Bavarian Health and Food Safety Authority, Luitpoldstraße 1, 97082 Würzburg, Germany.
authors: Verena
authors: V
authors: Koospal
authors: ‡Bavarian Health and Food Safety Authority, Luitpoldstraße 1, 97082 Würzburg, Germany.
authors: Claudia
authors: C
authors: Bauer-Christoph
authors: ‡Bavarian Health and Food Safety Authority, Luitpoldstraße 1, 97082 Würzburg, Germany.
authors: Norbert
authors: N
authors: Christoph
authors: ‡Bavarian Health and Food Safety Authority, Luitpoldstraße 1, 97082 Würzburg, Germany.
authors: Helmut
authors: H
authors: Wachter
authors: §Spectral Service, Emil-Hoffmann-Straße 33, 50996 Köln, Germany.
authors: Bernd
authors: B
authors: Diehl
authors: †Institute of Pharmacy and Food Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors: Ulrike
authors: U
authors: Holzgrabe
mesh_terms: D000434:Alcoholic Beverages / Q000032:analysis*; D000818:Animals; D002241:Carbohydrates / Q000032:analysis*; D002417:Cattle; D002645:Chickens; D004530:Egg Yolk / Q000737:chemistry*; D000431:Ethanol / Q000032:analysis*; D008892:Milk / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*
chemical_list: D002241:Carbohydrates; D000431:Ethanol
keywords: alcoholic strength; cholesterol; egg liqueur; egg yolk; qNMR; quantitative 1H NMR; total sugar