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In fresh pork loin, the information concerning fat content is very important, both from the consumer as well as from the nutritional point of view. Knowing the fat content allows industry to classify the fresh loins accordingly. Fat content in loins is a factor related to moisture variability; therefore on-line, non-destructive technologies that could be used in an industrial environment to predict fat-to-moisture ratio are of special interest for companies from the pork processing sector. The time-domain nuclear magnetic resonance (1H TD-NMR), and in particular Relaxometry and Imaging (MRI), has been introduced as a promising alternative to traditional food characterization method due to its rapidity, simplicity, and potential for on-line non-destructive measurements. In this paper, the authors introduce original and innovative procedures using NMR Relaxometry and 1H nuclei imaging which can be employed to estimate the fat content in intact pork loins by exploiting the difference between fat and water longitudinal relaxation time (T1) distributions. They demonstrate how analysis of the quasi-continuous distributions of T1 in fresh intact loins allowed them to obtain a significant relationship between F/W ratios determined from Relaxometry and chemical analysis. This chapter also explains how both NMR Relaxometry and Imaging can estimate the fat-to-moisture ratios in loins in a non-destructive way.

The collection and composting of organic waste from both households and industries has long been recognized as a valuable contribution to waste management. The first step towards a “zero-waste” concept, in particular in the food processing sector, is the identification, quantification and characterization of residues. Thus considerable efforts have been focused towards the definition of compost maturity in order to decide on the quality of compost. Therefore the principal requirement of a compost for its safe use is a high degree of maturity, which implies a stable organic matter (OM) content and the absence of phytotoxic compounds and plant or animal pathogens. Magnetic Resonance Relaxometry (MRR) and Imaging (MRI) of hydrogen nuclei are optimal candidates to give information on the degree of degradation and maturity of compost, especially when there is needed a careful non-invasive and non-destructive characterization. Because many foods are proton-rich, e.g., from water, fat, carbohydrates, and proteins, MRR is a common tool to gain information about the composition and internal structure of foods, permitting also to monitor the compositional and structural modifications when they undergo natural or artificial processes. Since the relaxation times (longitudinal T1 and transverse T2) variations change the image contrast, MRI can easily monitor the structural changes in foods during processing and storage. MRI can detect and show internal variations in the water content, as well as changes in water interaction with cellular tissues. In this work typical MRR parameters as T1 and T2, and 1H signal amplitude were related to water content, and to micro and molecular structure of the compost itself, to follow the compost phases. Furthermore the authors used Quantitative Relaxation Tomography (QRT), a method to measure locally the relaxation times by means of MRI images. This technique allowed them to locally follow the FW biodegradation over time and to evaluate the maturity and quality parameters. In summary, matching magnetic resonance techniques with other standard analyses could be of great importance to fully describe the stages of composting and define the degree of compost maturity.

In order to well distinguish different tissues of the human body, it is of paramount importance to find procedures and sequences that improve the contrast of Magnetic Resonance Imaging (MRI) images. In particular, the possibility to image only specific parts of organs and/or tissues while ignoring all the others is a very valuable feature. A way to address this problem is to develop dedicated MRI sequences able to filter the 1H nuclei signals on the basis of the different longitudinal relaxation times (T1) of the tissues and to produce images where components are suppressed. Instead of using standard signal selection/attenuation sequences, such as the Short Time Inversion Recovery and Multiple Inversion Recovery, whose effects are to zero the signal for a discrete number of T1 values, we developed the Parametrically Enabled Relaxation Filters with Double and multiple Inversion (PERFIDI) filter sequences. These sequences acting on a range of T1 behave as electronic band-pass, high-pass and low-pass filters, primarily focused on the components which pass through, rather than on those blocked. We tested PERFIDI filter sequences on a synthetic two-component test tube sample. Preliminary applications on biological tissues have shown that this technique can effectively work on a range of T1 values.

Fat suppression in Magnetic Resonance Imaging (MRI) images is an important diagnostic topic. In this work, through NMR Relaxometry and Imaging of 1H nuclei we estimated the Fat/Water (F/W) ratio on pig loins, assumed as model of human muscle tissue, by analyzing 1H longitudinal relaxation times (T1) distributions and quantitative MRI images. It is known that water and fat proton signals in tissues have different T1 values. The innovative characteristic of our approach is to assume that T1 values follow a quasi-continuous distribution, instead of a discrete distribution. F/W ratios of the samples were determined through NMR Relaxometry by distinguishing the signal of fat 1H nuclei from that of the water through the choice of a proper cut-off on the T1 distributions. F/W ratio was determined on MRI images acquired with the “classic” Short Time Inversion Recovery sequence. Innovative Parametrically Enabled Relaxation Filters with Double and multiple Inversion (PERFIDI) sequences, that implement band-pass filters, were also used. The correlation between NMR and an independent destructive chemical analysis performed on the same samples gave very good results for both Relaxometry and Imaging techniques.