The use of elastography to measure quality characteristics of pork semimembranosus muscle

摘要

The ohjectives of this study were to determine if ultrasonic strain image analysis could estimate pork eating quality parameters (such as fresh color, drip loss, and Warner/Bratzler shear). Intact semimembranosus (SM) muscles (cap off) were analyzed for ulti- mate pH (pH_ult). Forty-five SM muscles were selected from the larger allotment of fresh hams over a 3-week period. The SM muscles were selected based on high and low pH_ult, in an attempt to represent a wide range of pork quality. Ultrasonic strain images were obtained perpendicular to the SM muscle fibers of an 8-cm cube. Radio-frequency data from each SM were obtained from a field-of-view (FOV) of 40×30 mm~2 and digitized for each compression step. Tissue displacements were computed for each com- pression step. Tissue strains were computed from displacement data located in the FOV representing areas of harder and softer muscle tissue and converted to gray scale images at 256 levels. Tissue irregularity of hardness and softness was measured using Fractal dimension and Haralicks parameters. Twenty-one Fractal dimension (FR) parameters, at two neighborhood distances (N), from each strain image and nine Haralick's (HAR) textural parameters (inter-pixel distance = 1) were analyzed for each image. The variable FR4N4 had a -0.279 correlation with SM ultimate pH (p < 0.10); FR6N8 correlated to WB shear force at 0.325 (p < 0.05); and FR21N8 had a correlation coefficient of 0.364 with intramuscular fat (p < 0.01). Linear regression equations generated from FRN and HAR parameters for intramuscular fat (R~2 = 0.468). Warner/Bratzler shear (R~2 = 0.360), and 30 h drip loss(R~2 = 0.208). Although elastographic measurement was significantly correlated to shear (p < 0.05), a better understanding of physical meat tex- ture is necessary before elastography can be used to identify superior quality pork.