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.

Complex Mixture Analysis of Organic Compounds in Yogurt by NMR Spectroscopy

“…NMR spectroscopy is highly quantitative and reproducible, and its sensitivity does not depend on the types of metabolites [ 1 ]. As a non-targeted method, NMR measurements do not require separation and chemical modification; therefore, comprehensive information regarding the chemical components of mixtures can be rapidly and directly provided [ 2 , 3 ]. For the past decade, NMR has been recognized as a powerful technique for discerning the chemical properties of complex mixtures and has been widely applied to identify organic compounds in foods, such as milk [ 4 ], soy sauce [ 5 ], coffee [ 6 ], wine [ 7 ], mango juice [ 8 ], and green tea [ 9 ].…”

Quantitative 1H-NMR Spectroscopy for Profiling Primary Metabolites in Mulberry Leaves

“…To reduce the total time spent on multiple scans, an inadequate time of relaxation delay (D 1 = 4 s) was set to acquire spectra in our work. We then employed external calibration for each metabolite to calculate their contents in extracts to avoid a potential error source of every step of sample treatment and testing [ 24 ]. The 1 H-NMR method was subsequently validated with respect to linearity, precision, repeatability, stability and accuracy ( Table 2 and Table 3 ):…”

Foodomics and Food Safety: Where We Are

“…In the last ten years, the number of quantitative NMR applications in foodomics has signifi cantly increased (93,94), especially toward detection and quantitative determination of specifi c molecules (95)(96)(97). NMR can be used for determining food origin (98-100), quality and purity (97,98,101).…”

“…NMR can be used for determining food origin (98-100), quality and purity (97,98,101). The most important application of NMR in the fi eld of safety is the use of this method for the determination of changes in food during storage, with particular emphasis on degradation processes and possible contamination with food pathogens and their toxins (93,94).…”

“…In general, 1 H NMR spectroscopy is the most frequently used method (95)(96)(97)(98)(99)108), but NMR spectroscopy can also detect other isotopes such as 13 C, 15 N, 17 O and 31 P (79,89,91,92,108). The advantages of NMR spectroscopy are that minimal sample preparation is necessary, and practically every kind of biological fl uids or food extracts can be analyzed using this method (91,92,108).…”