Enzymatic hydrolysis is becoming a more commonly used method to create high value products from traditionally low value marine by-products. However, improvement to processing is hampered by a lack of ways to characterize the reaction in real time. Current methods of analysis rely on taking offline samples, deactivating the enzymes, and performing analysis on the products afterwards. Nuclear magnetic resonance benchtop spectroscopy was investigated as a method for online process monitoring of enzymatic hydrolysis. Online and offline NMR measurements were performed for enzymatic hydrolysis reactions on red cod, salmon and shrimp. Both the online and offline measurements were able to follow the reaction process and showed good agreement in their calculated reaction rate. Application of the methodology to several types of raw materials indicates the technique is robust with regards to sample type. Advantages and disadvantages of low-field versus high-field NMR spectroscopy are discussed as well as practical considerations needed in order to apply the method industrially.

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Nuclear magnetic resonance (NMR), and in particular transverse relaxation (T2), has been used to characterize meat and seafood products for decades. Despite many years of research, it is still not possible to reproducibly correlate the transverse relaxation of muscle foods to attributes that determine their quality and value. Instead of directly trying to interpret the T2 spectrum itself, typically chemometrics is used to try to relate the relaxation distributions to other measured properties on the sample. As muscle tissue is a porous medium, it is tempting to use equations developed to analyze other porous systems to provide a more direct, quantitative description of the tissue. However, the standard equations used to characterize porous materials have been developed for predominantly geological systems. This article discusses the foundations of transverse relaxation theory in porous media and the challenges that arise when attempting to adapt the equations to a biological system like tissue.One of the biggest issues that needs to be overcome before porous media theory can be reliably applied to characterize meat and seafood is to determine the source of relaxivity in the tissue. In order to better understand how the NMR signal originates, T2, diffusion, T1-T2 correlation and T2-T2 exchange experiments were performed on Atlantic cod (Gadus morhua) tissue in a variety of states (e.g. fresh, thawed, homogenized, etc.). In the literature, typically four T2 peaks are reported for meat and seafood samples. Results of this study

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