Nondestructive measurement of intramuscular fat content of fresh beef meat by a hand-held magnetic resonance sensor

Abstract

ABSTRACT To realize nondestructive in-situ quantification of intramuscular fat in fresh beef meat, a lightweight (5.0-kg) hand-held sensor that consists of a planar radio-frequency coil and a unilateral (i.e., single-sided) magnetic circuit was constructed as a subunit of a time-domain proton magnetic resonance (MR) scanner system. The MR scanner based on proton relaxometry enables the nondestructive quantification of the fat content of meat by using the difference in the spin-spin relaxation times (T2) of water molecules in muscle and of fat molecules. The investigation depth of the sensor unit was 7 mm, which is sufficient to probe the meat beneath a subcutaneous fat layer less than a few millimeters thick. The scanner was successfully applied in a laboratory at a meat temperature of 30.5°C to quantify the fat content at 30 locations in fresh beef samples. The required measurement time was 22 s for each location. Reasonable agreement with a root-mean-square error as small as 5.4 wt% was obtained for fat quantification compared with the conventional destructive food analysis (Soxhlet extraction method). Thus, the portable MR scanner with a hand-held sensor unit is a promising nondestructive and noninvasive tool for the in-situ fat quantification of fresh beef (e.g., carcasses) with thin subcutaneous fat layers at meat processing factories.