On-Site Measurement of Fat and Protein Contents in Milk Using Mobile NMR Technology

Abstract

Robust and easy-to-use NMR sensor technology is proposed for accurate, on-site determination of fat and protein contents in milk. The two parameters are determined using fast consecutive 1H and 35Cl low-field NMR experiments on milk samples upon the 1:1 addition of a low-cost contrast solution. Reliable and accurate measurements are obtained without tedious calibrations and the need for extensive database information and may readily be conducted by non-experts in production site environments. This enables on-site application at farms or dairies, or use in laboratories harvesting significant reductions in costs and time per analysis as compared to wet-chemistry analysis. The performance is demonstrated for calibration samples, various supermarket milk products, and raw milk samples, of which some were analyzed directly in the milking room. To illustrate the wide application range, the supermarket milk products included both conventionally/organically produced, lactose-free milk, cow’s, sheep’s and goat’s milk, homogenized and unhomogenized milk, and a broad nutrient range (0.1–9% fat, 1–6% protein). Excellent agreement between NMR measurements and reference values, without corrections or changes in calibration for various products and during extensive periods of experiment conduction (4 months) demonstrates the robustness of the procedure and instrumentation. For the raw milk samples, correlations between NMR and IR, NMR and wet-chemistry, as well as IR and wet-chemistry results, show that NMR, in terms of accuracy, compares favorably with the other methods.

Bovine milk β‐casein: Structure, properties, isolation, and targeted application of isolated products

“…The proteins in bovine milk contain all the essential amino acids required by the human body and have high digestibility, making it an important source of high‐quality protein. Bovine milk proteins consist of casein and whey proteins (Sørensen et al., 2022). The protein content of bovine milk is about 2.9%–5.0%, casein is the main component, generally accounted for 80% of milk proteins, its isoelectric point is 4.6 under the condition of 20°C; the rest of the class is basically whey proteins, accounting for about 20%.…”

“…Bovine milk proteins consist of casein and whey proteins (Sørensen et al, 2022). The protein content of bovine milk is about 2.9%-5.0%, casein is the main component, generally accounted for 80% of milk proteins, its isoelectric point is 4.6 under the condition of 20 • C; the rest of the class is basically whey proteins, accounting for about 20%.…”

Nitrogen Emission from Livestock Housings Quantified Combining a Mass-Balance Model and Low-Field NMR Sensoring

“…The required analytical input may be obtained by traditional laboratory methods but much more conveniently with accurate on-site measurements such as obtained using a mobile NMR sensor. Such technology is robust and easy to use, and in the context of farming it has recently been demonstrated to be powerful for quantification of nutrients in manure, , livestock feed, and milk …”

“…Such technology is robust and easy to use, and in the context of farming it has recently been demonstrated to be powerful for quantification of nutrients in manure, 10,11 livestock feed, 12 and milk. 13 To demonstrate our proposed concept of using a tracer-ratio method to quantify gaseous N loss from manure, we conducted a full-scale, barn experiment with dairy cows during a period of 3 months. In this experimental demonstration, all relevant nutrient inputs and outputs were quantified to obtain a full mass balance, including gas measurements of the NH 3 emission for comparison with the results obtained using the tracer-ratio method.…”

Magnetic Resonance and Vibrational Spectroscopy and Imaging in Food Analysis

“…This Special Issue, "Magnetic Resonance and Vibrational Spectroscopy and Imaging in Food Analysis", published in the journal Molecules, includes ten original papers: seven papers using nuclear magnetic resonance spectroscopy and relaxometry (NMR) and imaging (MRI), and three papers using near-and middle-infrared spectroscopy and hyperspectral imaging. The NMR papers are as follows: Sørensen et al [1] demonstrate the use of portable and easy-to-use NMR instruments to measure fat and protein content in milk, on site. Salvador et al [2] show the use of high-and low-field NMR spectroscopy to monitor the effect of UV-C light on the bean-darkening process.…”