A low-field Nuclear Magnetic Resonance dataset of whole milk during coagulation and syneresis.

We report the relaxometric dataset obtained on renneted milk during syneresis by Time-Domain Nuclear Magnetic Resonance spectroscopy (TD-NMR). Data were obtained on cow's milk provided by two different producers in two different lactation seasons (April and October) and on a group of goat's milk samples (one season, November-December, one producer). TD-NMR data refer to spin-spin relaxation times (T2) decay curves and distributions measured at 40 °C at seven time points after rennet addition, up to 70 minutes of syneresis. Curd was cut 30 min after rennet addition without removing the NMR tube from the TD-NMR instrument. The dataset here reported is related to the research article entitled "Non invasive monitoring of curd syneresis upon renneting of raw and heat-treated cow's and goat's milk" [E. Curti, A. Pardu, S. Del Vigo, R. Sanna, R. Anedda, Non-invasive monitoring of curd syneresis upon renneting of raw and heat-treated cow's and goat's milk, Int. Dairy J. 90 (2019) 95-97].

Data

TD-NMR technique showed its ability and suitability in unraveling dairy products features and quality attributes [1], [2], [3]. Heating is known to affect milk functional properties [4], [5] and, consequently, the following processing steps in cheese manufacturing. With TD-NMR being able to highlight molecular changes related to coagulation and syneresis [6], [7], a TD-NMR T2 dataset of whole milk is here presented, to deepen the knowledge of the syneresis process. Both raw (T2 decays, Fig. 1a) and processed (T2 distributions, Fig. 1b) data of raw and heat-treated cow's and goat's milk (after rennet addition, and up to 70 minutes of syneresis) [1] are provided as supplementary files, with an explanatory legend. Representative examples of the differences between the NMR relaxometric profiles of raw and heat-treated milk (Fig. 2a) and curd (Fig. 2b) are also reported.

Fig. 1

Dataset on curds during syneresis. Representative graphical examples of (a) CPMG signal decays and (b) T2 quasi-continuous distributions obtained by using CONTIN software.

Fig. 2

(a) T2 quasi-continuous distributions (CONTIN) of milk immediately after rennet addition (at T0) and (b) on curds after 70 min (T6). Solid lines refer to raw milk and derived curd, dashed lines represent the heat-treated counterparts.

Experimental design, materials, and methods

Sample preparation

Fresh whole raw milk was collected and heat-treated at 72 °C. Raw and heat-treated milk samples were put into NMR glass tubes and inserted inside the magnet to equilibrate at 40 °C. Liquid rennet (Naturen®, Christian Hansen, Parma, Italy) was added to milk inside the NMR tubes, where curd evolution was monitored during coagulation and syneresis.

Curd syneresis monitoring

T2 distributions were acquired at T0 (just after rennet addition),T3C (curd cutting), and every 10 minutes until 70 minutes (T4, T5, T6 and T7).

TD-NMR analysis

A low-field Nuclear Magnetic Resonance spectrometer was used (Bruker the miniSpec, Germany). 1H T2 decays were acquired with a Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence (recycle delay: 6 s; interpulse spacing 0.05 ms; 8 scans; 8000 data points) [Bruker the miniSpec (20MHz, 0.47T), Germany] and T2 quasi-continuous distributions (400 points; range: 1–3000 ms) were obtained (CONTIN Bruker software).

Specifications Table

Subject area	Food Chemistry
More specific subject area	Dairy Science
Type of data	xlsx file (XY data table)
How data was acquired	Low-field Nuclear Magnetic Resonance Spectrometer (20 MHz, 0.47 T, Bruker the miniSpec, Germany)
Data format	Raw and processed (CONTIN software, Bruker, Germany) T2CPMG decays
Experimental factors	Fresh whole milk was analyzed raw and heat-treated
Experimental features	1. Heat treatment of milk (72°C, 1 minute)2. Addition of rennet, coagulation and syneresis3. Acquisitions of T2[transverse relaxation time, Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence] decays at selected syneresis time points, up to 70 minutes4. Analysis of T2data decays with CONTIN software to obtain T2distributions5. Comparison of T2distributions of raw and heat-treated milk and curd
Data source location	Porto Conte Ricerche S.r.l., Tramariglio, Alghero (SS), Italy
Data accessibility	Data are included in this article, as a supplementary file
Related research article	Curti, E. Pardu, A., Del Vigo, S. Sanna, R., and Anedda R. Non invasive monitoring of curd syneresis upon renneting of raw and heat-treated cow's and goat's milk. Int. Dairy J. 90 (2019) 95–97. https://doi.org/10.1016/j.idairyj.2018.11.003

Value of the Data• The dataset is useful to demonstrate and understand the effect of heat treatments of milk on the microstructural features of curd during syneresis • The dataset can be useful to both researchers involved in the application of NMR relaxometry in dairy science and to dairy technologists • The dataset can be used as a comparison in studies investigating the effect of other parameters (e.g. season, cattle diet, cattle species, rearing environment, climate) on milk and curd microstructural features. • To the best of our knowledge, this is the first published NMR relaxometry dataset on whole milk • Our dataset would serve as a starting point for the implementation of NMR in process and quality control of dairy products