Development of a hand-held magnetic resonance sensor for the nondestructive quantification of fat and lean meat of fresh tuna

Yoshito Nakashima

doi:10.1007/s11694-020-00539-5

Abstract

For the in-situ nondestructive fat quantification of fresh tuna meat, an original lightweight (5.7 kg) hand-held sensor that consists of a planar radio-frequency coil and a single-sided magnetic circuit was developed as a subunit of a time-domain proton magnetic resonance (MR) scanner system. The investigation depth of the sensor unit is 12 mm, which is sufficient to probe the meat section beneath thick skin with scales and the underlying subcutaneous fat layer of large fish such as tuna. The scanner was successfully applied in a laboratory to a fillet of a bluefin tuna (Thunnus thynnus) to measure meat sections 12 mm beneath the skin. The required measurement time was 100 s for each section. The results of MR scan at 11 locations on the fillet were compared with those of conventional destructive food analysis. Reasonable agreement with an error (root-mean-square residual) of as small as 1.8 wt% was obtained for fat quantification. The time-domain MR relaxometry for the same tuna fillet also allowed lean meat quantification with a small root-mean-square residual of 6.7 wt%.

Highlights

The fat content of tuna meat affects consumers’ sense of taste and determines price [1, 2]
An magnetic resonance (MR) surface scanner based on proton relaxometry enables the nondestructive quantification of the fat content of meat by utilizing the difference in the spin–spin relaxation times of water molecules in lean meat and fat molecules
An original hand-held sensor unit was developed for the MR surface scanner to quantify the fat content of fresh tuna

Summary

Introduction

The fat content of tuna meat affects consumers’ sense of taste and determines price [1, 2]. It is desirable to nondestructively measure the fat content of fresh tuna using lightweight hand-held sensors at markets and sea-food processing plants [3,4,5,6,7,8] to accurately assess the value and price of whole fish. Portable surface scanners that employ low-field single-sided (i.e. unilateral) magnetic resonance (MR) relaxometry [9,10,11,12,13,14] are one of the most promising techniques for the in-situ nondestructive quantification of the fat content of fish. An original lightweight sensor unit (5.7 kg) is designed and constructed.

Methods

Results

Discussion

Conclusion