Use of NMR in fish processing optimization: a review of recent progress.

The goal of this review is to give an overview of general trends in the application of the NMR related to fish processing and quality and to provide some viewpoints on the current situation. Three novel examples of the application of the methodologies magnetic resonance spectroscopy, magnetic resonance imaging, and low-field NMR are also presented. The capability of these techniques to be utilized as a tool to optimize fish processing, and thereby improving product quality, as well as to confirm labelling information, are demonstrated.

A simple method for weight estimation of whole herring (Clupea harengus) using planar X-ray imaging.

Fish weight is one of the key parameters used in commercial sorting of fresh fish. The capability of on-line and accurate estimation of the weight of each individual fish has a direct impact on profitability for the fish processors. Planar X-ray images of whole herring (n=16) were taken using a commercial medical X-ray apparatus.

Quantitative 23Na magnetic resonance imaging of model foods.

Partial (23)Na MRI invisibility in muscle foods is often referred to as an inherent drawback of the MRI technique, impairing quantitative sodium analysis. Several model samples were designed to simulate muscle foods with a broad variation in protein, fat, moisture, and salt content. (23)Na spin-echo MRI and a recently developed (23)Na SPRITE MRI approach were compared for quantitative sodium imaging, demonstrating the possibility of accurate quantitative (23)Na MRI by the latter method.

Water and salt distribution in Atlantic salmon (Salmo salar) studied by low-field 1H NMR, 1H and 23Na MRI and light microscopy: effects of raw material quality and brine salting.

The effect of different Atlantic salmon raw materials (prerigor, postrigor and frozen/thawed) on water mobility and salt uptake after brine salting was investigated by using LF 1H NMR T2 relaxation,1H and 23Na MRI and light microscopy. Distributed exponential analysis of the T2 relaxation data revealed two main water pools in all raw materials, T21 and T22, with relaxation times in the range of 20-100 ms and 100-300 ms, respectively. Raw material differences were reflected in the T2 relaxation data.

(1)H and (23)Na MRI studies of Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) fillet pieces salted in different brine concentrations.

Background: Applicability of magnetic resonance imaging (MRI) to quantitative analysis of sodium in salted fish products is usually impaired by the partial (23)Na MRI 'invisibility' phenomena as well as high investment costs of the MRI equipment.

Results: Salmon and cod fillet pieces, unsalted and brine salted (50, 100, 150, 200 and 250 g kg(-1) NaCl) for 48 h, were studied using (1)H and (23)Na MRI. Based on MRI results, T(1) and T(2) relaxation times were calculated for (1)H and the T(2) time for (23)Na nuclei.