Variable Temperature Nuclear Magnetic Resonance and Magnetic Resonance Imaging System as a Novel Technique for In Situ Monitoring of Food Phase Transition

A nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) system with a 45 mm variable temperature (VT) sample probe (VT-NMR-MRI) was developed as an innovative technique for in situ monitoring of food phase transition. The system was designed to allow for dual deployment in either a freezing (−37 °C) or high temperature (150 °C) environment. The major breakthrough of the developed VT-NMR-MRI system is that it is able to measure the water states simultaneously in situ during food processing. The performance of the VT-NMR-MRI system was evaluated by measuring the phase transition for salmon flesh and hen egg samples. The NMR relaxometry results demonstrated that the freezing point of salmon flesh was −8.08 °C, and the salmon flesh denaturation temperature was 42.16 °C. The protein denaturation of egg was 70.61 °C, and the protein denaturation occurred at 24.12 min. Meanwhile, the use of MRI in phase transition of food was also investigated to gain internal structural information. All these results showed that the VT-NMR-MRI system provided an effective means for in situ monitoring of phase transition in food processing

Kernels of different shapes.

<p>Left: round shape corns; right: flat shape corns.</p

Schematic diagram of the single kernel feeder.

<p>1: Sample hopper; 2: Picker unit that sucks in a single kernel; 3: Stepping motor unit; 4: Pit; 5: Sample blowing pipe; 6: Weighing sensor; 7: Sample pipeline; 8: Kernels.</p

Plot of the echo amplitude (open squares) as a function of half echo time.

<p>The green line is the signal of bound water and the red line that of oil. Since the bound water decays quickly, thus the signal at TE = 7.5 ms is only contributed from the oil.</p

Fully-Automated High-Throughput NMR System for Screening of Haploid Kernels of Maize (Corn) by Measurement of Oil Content - Fig 10

<p><b>Left panel:</b> The distribution of ZD958 kernels weight (haploids, diploids and total kernels are shown as circles, squares and pluses, respectively) and their fitting distributions (haploids, diploids and total kernels are shown as a dash line, a dot-dash line and a solid line respectively). <b>Right panel:</b> The OCR distribution of ZA958 kernels (haploids and diploids are shown as circles and squares respectively) and their fitting distributions (haploids and diploids are shown as a dash line and a dot-dash line respectively). It shows that an OCR threshold of 4.25% can well distinguish diploids from haploids.</p

Schematic diagram of the kernel sorter.

<p>1: Sample pipeline; 2: Sort pipeline; 3: Kernel; 4: Sample plug; 5: Cylinder; 6: Sorting plug.</p

The photographs of the haploid and diploid of Zheng58 and Yu87-1.

<p>(a) Zheng58, the left 2 kernels are haploid, and the right 2 kernels are diploid; (b) Yu87-1, left 2 kernels are haploid and the right 2 kernels are diploid.</p

Schematic diagram of the NMR sample holder.

<p>1: Sample pipeline; 2: Magnet; 3: RF coil; 4: Kernel; 5: Sample plug.</p

Test of statistical significance of the accuracy obtained under different acquisition times.

<p>Note: d<i>f</i> is degree of freedom; Sig. (2 tailed): the two tailed value probability value; <i>y</i>1 and <i>y</i>2: oil content ratio at measurement time of 1 and 2 s, respectively. The original data for this analysis is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159444#pone.0159444.g008" target="_blank">Fig 8</a>.</p

The block diagram of the software for the automatic measurement and sample handling.

<p>The block diagram of the software for the automatic measurement and sample handling.</p