Background

For over 60 years meat scientists have been investigating characteristics of individual muscles. Through the year’s scientists have completed studies that included many muscles and few animals as well as few muscles over many animals. Not surprisingly, the relative tenderness of specific muscles has not always agreed. The objective of this study was to create a weighted ranking of muscles based on a comprehensive review of the literature. 

Methodology

A comprehensive review of literature began by searching for all papers that studied at least 3 muscles from a minimum of 3 animals for any of the following: Warner-Bratzler shear force (WBS), sensory panel ratings for tenderness, juiciness, and beef flavor. The muscle number criterion was set to select papers that were interested in comparing and analyzing individual muscles. At the same time, if fewer than 3 animals were used, the study offered less comparative value.  

Following the initial criteria, 58 papers were identified spanning 6 decades and many institutions. However, these studies included a wide variety of protocols. Age of animals varied from 10 months to over 11 years of age. Heifers, steers, and bulls from Bos indicus to dairy type breeds were used. USDA yield grades ranged from 1 to 5 and quality grades included nearly all grades for both young and mature beef. Aging periods varied from 1 to 28 days. Both steaks and roasts were cooked to an end point temperature ranging from 57-85°C using a wide variety of cooking methods. Samples were then evaluated for WBS using 1.2 to 2.54 cm cores. Sensory panel rating scales offered 5 to 10 classifications.  

Due to these differences, constraints were placed on which papers were used to determine the overall rankings. Selection was based around traits typical of the U.S. market beef population. Acceptable studies included steers, heifers, or both that were under 30 months of age or were A or B maturity carcasses from any quality grade. Purebred Bos indicus were excluded, but crossbreds were allowed. Additional constraints were added to handling and testing techniques. Steaks were cooked or frozen from 5 to 14 days post slaughter. Moist cooking methods were excluded for consistency and products were cooked to an end point temperature range of 70-77°C. Papers were narrowed to those that used 1.2-1.3 cm cores for WBS. Only trained sensory panels were chosen but no selection was placed on rating scale. Ultimately, 22 papers were used for ranking muscles on the basis of WBS. There were 11 papers for ranking on tenderness ratings, 11 for ranking by juiciness, and 6 for beef flavor.  

Muscles, weighted by number of observations, were analyzed for WBS using Proc GLM and LS Means function of SAS to create a rank. Sensory panel ratings were analyzed in the same method after being standardized to a 100 point scale. Proc Corr was used to analyze the correlation of ranks and means for WBS and sensory panel.  

Muscles were placed in 3 tenderness groups on the basis of WBS: tender (<3.9 kg), intermediate (3.9 kg4.6 kg). The sensory panel results were placed in eight groups: <18.75, and in increments of 12.5 beyond that for tenderness, juiciness, and beef flavor. Muscle abbreviations are found in Table 1. 

Findings

Of the 40 muscles ranked for WBS (Figure1), psoas major, infraspinatus, spinalis dorsi, serratus ventralis, multifidus dorsi, subscapularis, and teres major were classified as tender (<3.9 lbs). The psoas major has long been utilized for its tenderness. The multifidus dorsi and spinalis dorsi are found in ribeye steaks and chuck eye rolls. The infraspinatus and teres major have been increasingly utilized as ‘value cut’ steaks. However, the serratus ventralis and subscapularis are under-utilized in relationship to their inherent shear values. The major muscles that were classified as the tough group (>4.6) were biceps femoris, supraspinatus, semitendinosus, deep pectoral, gluteus medius, vastus lateralis, rhomboideus, and the longissimus dorsi in the chuck region. Although the gluteus medius is often used as a steak, it only ranked 31 of 40 for WBS values.  

For muscles analyzed by sensory panel, all steaks that had a tenderness (n=14) rating greater than or equal to a six point equivalent on an eight point scale also had a WBS less than 4.5kg (Figure 2). For juiciness (n=13), the infraspinatus, serratus ventralis, and longissimus lumborum were among the highest rated and gluteus medius, semimembranosus, and semitendinosus were among the least juicy (Figure 3). There were no differences in sensory ratings for beef flavor (n=9) (Figure 4).  

The correlation between sensory panel tenderness ratings and WBS values for 14 muscles was evaluated. Means tenderness ratings had a correlation to mean shear force value, by muscle, of -0.85 (p=0.001) (Figure 5). The numerical ranks had a correlation of 0.74 (p = .003) (Figure 6). It is well known that muscles vary in tenderness from one end to the other. Unfortunately, authors rarely describe the precise anatomical location from which samples are derived. In addition, differences exist in the relative contribution of connective tissue and muscle fiber tenderness to WBS versus sensory tenderness ratings. These two situations may account for some of the differences. 

Implications

Combining 60 years of literature, 40 different beef muscles were ranked by Warner-Bratzler shear force. Relative ranks for tenderness, juiciness and beef flavor ratings were also determined. The psoas major and infraspinatus are the two most tender. Sensory tenderness ratings correlated to shear force means (-0.85; P=0.001). These data help reconcile differences among various studies of beef tenderness and provide a weighted ranking for beef muscles, which will be useful when selecting muscles for value-added beef products.