Nature and Variability of Marbling Deposits in Longissimus Dorsi Muscle of Beef Carcasses

Abstract

This study was undertaken to determine the amount of variation of intramuscular fat (marbling) within a section of the longissimus dorsi (rib-eye) muscle of beef carcasses. The rib-eye muscle comprising the 9th, 10th and 11th rib section was frozen and then cut into ¼-in. cross-sectional slices. Each slice was thawed and then graded for marbling according to U.S.D.A. Grading Standards with the exception that each grade was further divided into upper, middle and lower one-thirds. A range in marbling grades by as much as 2/3 was found among the slices within one rib-eye muscle section. Standard deviations of marbling scores among the muscles ranged from 0.65 to 2.75. Photographs illustrating some of the marbling patterns are included. The marbling pattern appeared to be somewhat consistent in that heavy marbling deposits occurred at more or less regular intervals within the rib-eye muscles.