Methodology

Product Selection
Trained Texas A&M personnel randomly selected USDA Top Choice (n=27) and USDA Select (n=27) carcasses (2 d postmortem) from a major packing facility (USDA, 1997). Paired beef subprimals – Beef Rib, Ribeye Roll, Lip-On, Bone In (Export Style) (similar to IMPS #109E) (n=108), Beef Loin, Strip Loin, Bone In (similar to IMPS #175) (n=108), and Beef Loin, Top Sirloin Butt, Boneless (similar to IMPS #184) (n=108) as defined by Institutional Meat Purchasing Specifications (IMPS) and described by USDA (1996) and NAMP (2003) were followed through the fabrication process, vacuum packaged, and shipped via refrigerated truck to the Rosenthal Meat Science and Technology Center at Texas A&M University.

Aging Treatments
Subprimals were received (9 d postmortem) at the Rosenthal Meat Science and Technology Center and a set of six subprimals of each type and grade group (n=36) were cut into 2.54 cm steaks, vacuum packaged, and immediately frozen. These steaks served as the baseline for tenderness and flavor assessments. The remaining subprimals (n=288) (6 replications x 2 grade groups x 3 subprimals x 4 aging periods x 2 aging treatments) were randomly assigned to one of two treatments, dry or wet aging, and to one of four aging periods, 14, 21, 28, or 35 days. Each carcass side (right and left) were represented equally among the aging treatments. Subprimals assigned to the dry aging treatment were weighed initially in the bag and weighed after bag removal to determine the amount of purge in the bag. The recorded weights would later be used to calculate the amount of shrink caused by the dry aging process. The subprimals then were placed on a stainless steel rack in the aging cooler. The subprimals assigned to the wet aging treatment were weighed in the vacuum package bag and placed back in the shipping boxes for the duration of the specified aging period. All subprimals were stored in a -0.6 ± 1.8°C, 78 ± 9.3% relative humidity cooler for the allotted aging period.

Cutting Tests
At the end of each specific aging period, cutting tests were performed in a retail cutting room at the Rosenthal Meat Science and Technology Center at Texas A&M University. Subprimals were fabricated by experienced meat cutters employed by Texas A&M University. Retail cutting tests consisted of three phases: opening (removal of subprimal from vacuum package bag), precut trimming (any trimming necessary before retail cuts could be made, i.e. removal of dried surfaces, removal of tails on strips and ribs if necessary, chining of strip loins, etc.), and cutting (producing tray-ready retail cuts, as described by Voges et al. (2006), and removal of external and seam fat as deemed necessary on certain cuts). After each cutting test, trained Texas A&M personnel recorded weights of all fabricated components: steaks, lean trim, stew meat, stir fry, fat trim, bone, bone dust, and waste. Weights were summed to ensure that at least 99% of the initial subprimal weight was recovered. For ribs and strip loins, band saws were cleaned of bone dust after every sixth subprimal. The bone dust was weighed and averaged across the six previous subprimals that were cut on that particular saw. Boneless top sirloin butts were cut on a band saw equipped with a boneless saw blade. No bone dust was recorded for the sirloins. Using handheld stopwatches, personnel were trained to record the time (s) necessary to complete each phase of the cutting test. Total time to complete each cutting test was calculated by combining times recorded for each phase of the cutting test.

Wet Aged Cutting Tests
Beef Rib, Ribeye Roll, Lip-On, Bone In (Export Style) (similar to IMPS #109E)
Vacuum packaged ribs were weighed in the bag (in bag weight), then taken out of the bag and reweighed (out of bag weight). In order for a purge loss value to be calculated, vacuum package bags then were washed, dried, and weighed. Using the band saw, ribs were cut into 2.54 cm-thick Beef Ribeye Steaks Lip-On BI (U.P.C. #1197). Universal Product Codes (U.P.C.), established by the Industry-Wide Cooperative Meat Identification Standards Committee (2003), were used to identify retail cuts. If necessary, steaks were trimmed to an external fat level of 0.3 cm. Beginning from the posterior end of the rib, steak one was designated for Warner-Bratzler shear (WBS) force determination, steaks two and three selected for consumer sensory evaluation, and steaks four and five reserved as extra steaks. For the 35 day cutting only, steaks six and seven were selected for use in a preference question for sensory evaluation.

Beef Loin, Strip Loin, Bone In (similar to IMPS #175)
Vacuum packaged strip loins were weighed in the bag (in bag weight), then taken out of the bag and reweighed (out of bag weight). In order for a purge loss value to be calculated, vacuum package bags then were washed, dried, and weighed. Using the band saw, strip loins were chined (body of vertebra removed to a point, deleting the spinal groove) and if necessary, the tail was removed. This operation was included in the waste trimming time. The trimmed strip loin was reweighed and its weight recorded as the subprimal ready to cut weight. The chine was weighed as pre-cut trimming bone weight. Trimmed strip loins then were cut into 2.54 cm-thick Beef Top Loin Steaks (U.P.C. #1398). If necessary, steaks were trimmed to an external fat level of 0.3 cm and a tail length of no longer than 1.27 cm. Beginning from the anterior end of the strip loin, steak one was designated for Warner-Bratzler shear (WBS) force determination, steaks two and three selected for consumer sensory evaluation, and steaks four and five reserved as extra steaks. For the 35 day cutting only, steaks six and seven were selected for use in a preference question for sensory evaluation.

Beef Loin, Top Sirloin Butt, Boneless (similar to IMPS #184)
Vacuum packaged sirloins were weighed in the bag (in bag weight), then taken out of the bag and reweighed (out of bag weight). For a purge loss value to be calculated, vacuum package bags were washed, dried, and weighed. No pre-trimming was required and subprimals were immediately cut into 2.54 cm-thick Beef Loin Top Sirloin Steaks Bnls (U.P.C. #1422). If necessary, steaks were trimmed to an external fat level of 0.3 cm. One total cutting time was recorded for wet aged sirloins. Beginning from the posterior end of the sirloin, steak one was designated for Warner-Bratzler shear (WBS) force determination, steaks two and three selected for consumer sensory evaluation, and steaks four and five reserved as extra steaks. For the 35 day cutting only, steaks four and five were selected for use in a preference question for sensory evaluation. Steaks six and seven, if available, were reserved for extra steaks.

Dry Aged Cutting Tests
Beef Rib, Ribeye Roll, Lip-On, Bone In (Export Style) (similar to IMPS #109E)
Dry aged ribs were weighed prior to cutting to determine an initial cut weight. Both anterior and posterior ends were faced on the band saw to remove the dried out surface tissue sometimes referred to as the “scab” and a time was recorded. The faced rib was then reweighed to get a subprimal ready-to-cut weight. The waste weight was recorded as pre-cut trimming (scab) weight. Steaks were cut in the same manner as the wet aged steaks. After steaks were cut, they were individually trimmed of dried surface tissue along the rib bone and the external surface. All dried surface tissue was classified as “waste.” Steak designation for shear force determination and sensory evaluation was the same as stated above for the wet aged steaks.

Beef Loin, Strip Loin, Bone In (similar to IMPS #175)
Dry aged strip loins were weighed prior to cutting to determine an initial cut weight. Both anterior and posterior ends were faced on the band saw to remove the dried surface tissue and the chine was removed. The faces were weighed as the pre-cut trimming (scab) weight and the chine was weighed as pre-cut trimming bone weight and the time was recorded. The trimmed strip loin was reweighed and the weight was recorded as the subprimal ready-to-cut weight. Steaks were cut in the same manner as the wet aged steaks. After steaks were cut, they were individually trimmed of dried surface tissue along the external surface. All dried surface tissue was classified as “waste.” All steaks were trimmed to an external fat level of 0.3 cm and a tail length of no longer than 1.27 cm. Steak designation for shear force determination and sensory evaluation was the same as stated above for wet aged steaks.

Beef Loin, Top Sirloin Butt, Boneless (similar to IMPS #184)
Dry aged sirloins were weighed prior to cutting to determine an initial cut weight. Steaks were cut in the same manner as the wet aged steaks. Steaks were individually trimmed of any dried surface tissue and external fat was trimmed to 0.3 cm. Only one total cutting time was recorded for dry aged sirloins. Steak designation for shear force determination and sensory evaluation was the same as stated above for wet aged steaks.

Consumer Panels
Consumer panelists for rib steaks (n=80), strip loin steaks (n=91), and sirloin steaks (n=90) were recruited from the Bryan/College Station area using an existing consumer database. Upon arrival at the sensory facility, panelists were asked to fill out a demographic survey. Tables 1-3 show the demographics by individual subprimal. Steaks selected for sensory evaluation were removed from the freezer 48 hours prior to cooking and allowed to thaw in the cooler (2°C). Steaks were cooked on indoor electric grills (Hamilton Beach Indoor/Outdoor Grill, Hamilton Beach/Proctor Silex, Inc., Southern Pines, NC) and temperature was continuously monitored by the use of Omega trendicators (Omega Engineering, Inc., Stamford, CT) fitted with type-T thermocouples. Steaks were cooked to an internal temperature of 35°C, flipped, and cooked to a final temperature of 70°C. The M. longissimus thoracis from the ribeye steaks, the M. longissimus lumborum from the strip loin steaks, and the M. gluteus medius from the sirloin steaks were used for evaluation. Two 1.27 cm cube samples from steaks representing individual subprimals randomly were served to panelists while seated in individual sensory booths. Consumers first were submitted to a two-sided directional difference test in which they were given a paired sample and were asked which sample they preferred (Meilgaard, Civille, & Carr, 2007). These paired samples consisted of one thirty-five day, dry aged and one thirty-five day, wet aged sample of USDA Choice or USDA Select grade. Panelists were asked to evaluate the remaining twelve samples using 10-point scales for overall like (OLIKE)(1=dislike extremely; 10=like extremely), flavor like (FLAV)(1=dislike extremely; 10=like extremely); level of beef flavor (FLVBF)(1=extremely bland or no flavor; 10=extremely flavorful or intense), tenderness like (TEND)(1=dislike extremely; 10=like extremely), level of tenderness (LEVTEND)(1=extremely tough; 10=extremely tender), juiciness like (JUIC)(1= dislike extremely; 10=like extremely), and level of juiciness (LEVJUIC)(1=extremely dry; 10=extremely juicy). Purchase appeal (PURCH)(1=definitely would not buy; 5=definitely would buy), the last question, used a 5-point scale. After the panelists finished their evaluations of all the samples, they were asked to complete a questionnaire to identify their individual perception of dry aged beef (Tables 4-6). Consumers were given a monetary award of $25 for their participation in this study.

Warner-Bratzler Shear Force Determination
Steaks designated for WBS force determination were removed from the freezer 48 hours prior to cooking and allowed to thaw in the cooler (2°C). Shear steaks were cooked and monitored in the same manner as the sensory steaks. Cooking yield percentages were determined from weights recorded before and after cooking. Total cooking time also was recorded for individual steaks. Steaks were covered and held overnight in a refrigerated cooler (2°C). Steaks were removed from the cooler and allowed to equilibrate to room temperature before coring. Six 1.27 cm cores were removed parallel to the muscle fibers from the M. longissimus thoracis from ribeye steaks, the M. longissimus lumborum from strip loin steaks, and the M. gluteus medius from sirloin steaks. Each core was sheared perpendicular to the muscle fibers using the Universal Testing System Machine (United 5STM-500, Huntington Beach, CA), equipped with a 25 lb (11.3 kg) load cell with a Warner-Bratzler shear attachment. The average of six cores was used to determine WBS force values.

Statistical Analysis
The effects of aging treatment, aging period, USDA quality grade, aging treatment x aging period, aging treatment x USDA quality grade, aging period x USDA quality grade were analyzed by analysis of variance programs using SAS PROC GLM (SAS Institute, Cary, NC). Interactions that were not significant were removed from the model. The p-diff option at P < 0.05 was used to separate means when significant differences occurred. Box-Cox transformation was used to ensure normal distribution for analysis of consumer data. Strip loin consumer data was analyzed using internal temperature endpoint as a covariate.

FINDINGS

Consumer Panels
Table 4 shows the exit interview for those panelists who evaluated ribeye steaks. Out of 80 panelists, 37.50% (30) of them stated they had eaten dry aged beef, 13.75% (11) had never eaten dry aged beef, and 48.75% (39) were not sure if they had eaten dry aged beef before. Twenty percent (16) of the panelists perceived dry aged beef to be better than other beef and 65.00% (52) were not sure if dry aged was better or the same as other beef. Furthermore, only 31.65% (25) of the panelists said they would spend $1.00 more per pound for dry aged beef.

Table 5 presents the exit interview for those panelists (n = 91) who evaluated the strip loin steaks and 32.22% (29) of the panelists had eaten dry aged beef before, 15.56% (14) had never eaten dry aged beef, and 52.22% (47) were not sure. Similar to the ribeye panelists, 25.56% (23) perceived dry aged beef to be better than other beef and 62.22% (56) were not sure if dry aged beef was better or the same as other beef. When asked if they would pay $1.00 more per pound for dry aged beef, 62.92% (56) of the panelists said they would not.

The exit interview for the panelists (n = 90) who participated in evaluating sirloin steaks is presented in Table 6 and 21.35% (19) of the panelists perceived dry aged beef to be better than other beef and 17.78% (16) of them thought that dry aged beef was safer to eat than other beef. Only 32.58% (29) indicated they would pay $1.00 more per pound for dry aged beef compared to other beef.

The effects of aging treatment on palatability characteristics of beef ribeye steaks are shown in Table 7. Wet aged ribeye steaks received higher (P = 0.0361) ratings than their dry aged counterparts for TEND. This is similar to Parrish et al. (1991) who found wet aged steaks had higher (P < 0.01) scores for tenderness. In the present study, no significant differences were found for OLIKE, FLAV, FLVBF, LEVTEND, JUIC, LEVJUIC, or PURCH between dry and wet aged ribeyes teaks. These results agree with studies done by Smith (2007), Sitz et al. (2006), and Parrish et al. (1991). In Smith (2007), overall like, flavor like, level of beef flavor, level of tenderness, juiciness like, level of juiciness, and purchase appeal attributes displayed no significant differences between dry and wet aged short loins. Sitz et al. (2006) found no significant differences between dry and wet aged strip loins for flavor, juiciness, or overall acceptability, Parrish et al. (1991) detected no significant differences in juiciness, flavor intensity, flavor desirability, or overall palatability between dry and wet aged ribs and loins. In the present study, the effect of aging period on palatability characteristics of beef ribeye steaks had no significant (P > 0.05) impact on any of the palatability attributes. However, TEND and LEVTEND ratings tended to increase with increased aging time. The effects of USDA quality grade on palatability characteristics of USDA Choice and USDA Select ribeye steaks are also shown in Table 7. For OLIKE, JUIC, and LEVJUIC, USDA Choice ribeye steaks were rated higher (P < 0.05) than USDA Select ribeye steaks. This is also similar to Smith (2007) where USDA Choice steaks rated significantly higher for overall like, juiciness, and level of juiciness when compared to USDA Select steaks.

Parrish et al. (1991) also found significant differences between USDA Choice and USDA Select ribeye steaks for juiciness and overall palatability. In this study, one significant interaction, aging day x aging treatment, was found for OLIKE and is presented in Figure 1. Consumers rated 14 d wet aged ribeye steaks and 35 d dry aged ribeye steaks higher (P = 0.0478) than 14 d dry aged ribeye steaks.

Table 8 shows the effect of aging treatment, aging period, and USDA quality grade on the palatability characteristics of beef steaks from strip loins. Although there were no significant differences between aging treatments for any of the attributes, wet aged strip loin steaks had higher ratings for FLVBF, TEND, LEVTEND, JUIC, and LEVJUIC when compared to dry aged strip loin steaks. Aging period also had no significant effect on the attributes; however, TEND and LEVTEND ratings tended to increase with increased aging time. USDA quality grade had a significant impact on the ratings of many attributes. USDA Choice strip loin steaks rated higher (P < 0.05) for OLIKE, FLAV, FLVBF, JUIC, and LEVJUIC than USDA Select strip loin steaks. As stated earlier, these data are similar to Smith (2007) and Parrish et al. (1991) who found significantly higher ratings for USDA Choice steaks when compared to USDA Select steaks for many sensory attributes. Contrarily, PURCH ratings for USDA Select strip loin steaks were higher (P = 0.0106) than USDA Choice steaks.

Effects of aging treatment, aging period, and USDA quality grade on the palatability characteristics of beef sirloin steaks from sirloins are shown in Table 9. No main effects significantly impacted palatability characteristics evaluated by the panelists. Although not significant, USDA Choice sirloin steaks had higher ratings than USDA Select sirloin steaks for the following attributes: OLIKE, FLAV, TEND, LEVTEND, JUIC, and LEVJUIC. Table 10 contains frequencies portraying consumers’ preference of aging treatment using a 2-sided directional difference test. Although there were no significant differences, consumers tended to prefer the wet aged ribeye and sirloin steaks to the dry aged steaks. Conversely, dry aged strip loin steaks tended to be preferred over the wet aged steaks.

Table 11 presents least squares means for cooking temperatures, cooking times, and cooking yields from consumer evaluations of beef ribeye, strip loin, and sirloin steaks. No main effects were significant for beef ribeye steaks. For strip loin steaks, the effects of aging period were significant on cooking time of steaks. 35 d aged strip loin steaks had the shortest (P = 0.0183) cooking time when compared to other aging days. One significant interaction, aging day x USDA quality grade, was found for total cooking time (Figure 2) in strip loin steaks. 35 d USDA Select strip loin steaks had significantly shorter cooking times when compared to the other grade and aging day combinations. Aging treatment had significantly affected total cooking time and cooking yield in sirloin steaks. Dry aged sirloin steaks had higher (P = 0.0005) cooking yield percentages and shorter (P < 0.0001) cooking times when compared to wet aged sirloin steaks. Likewise, Warren and Kastner (1992) found, although not significantly different, cooking time and cooking loss percentage were lowest for dry aged samples when compared to vacuum aged strip loin samples. Figure 3 presents a significant interaction between aging treatment and USDA quality grade for total cooking time for sirloin steaks. Similarly to the strip loins, dry aged USDA Choice and dry aged USDA Select sirloin steaks had shorter (P = 0.0285) cooking times than their wet aged counterparts.

Warner-Bratzler shear force determination
Least squares means for cooking temperatures, cooking times, cooking yields, and WBS values for beef steaks assigned to shear force determination are presented in Table 12. Aging treatment significantly impacted WBS values of ribeye steaks. Wet aged ribeye steaks had lower (P = 0.0064) WBS values than dry aged ribeye steaks. Furthermore, USDA quality grade significantly affected total cooking time for ribeye steaks. USDA Choice ribeye steaks had longer (P = 0.0133) cooking times than USDA Select ribeye steaks.

Cooking yield percentages of strip loin steaks were significantly impacted by aging treatment. Dry aged strip loin steaks had higher (P = 0.0009) cooking yield percentages compared to wet aged strip loin steaks. Figure 4 shows the least squares means for total cooking time of strip loin steaks. 35 d USDA Select strip loin steaks had shorter (P = 0.0311) cooking times than other grade and aging day combinations. Also, 14 d USDA Select strip loin steaks had the longest cooking time when compared to other combinations.

Aging treatment and aging period for sirloin steaks significantly affected total cooking time, cooking yield, and WBS values. Wet aged sirloin steaks had longer (P = 0.0003) cooking times, higher (P = 0.0145) WBS values, and lower (P = 0.0235) cooking yield percentages when compared to dry aged sirloin steaks. The longer cooking times and lower cooking yield percentages for wet aged sirloin steaks mimics results from sirloin steaks cooked for consumer evaluation stated earlier. Moreover, 14 d sirloin steaks had higher (P = 0.0012) WBS values than any other aging day. One significant interaction, aging day x USDA quality grade, was found for WBS values in sirloin steaks and is presented in Figure 5. 14 d USDA Select steaks had the highest (P = 0.0020) WBS values and 28 d USDA Choice steaks had the lowest WBS values compared to other aging day and USDA grade combinations. Aging 21 and 35 d had similar effects on WBS values in sirloins, therefore aging a minimum of 21 days would be beneficial to increase tenderness of sirloin steaks.

Least squares means of palatability characteristics for baseline ribeye steaks evaluated by consumers is shown in Table 13. USDA Choice ribeye steaks received higher (P < 0.05) ratings for LEVTEND, JUIC, and LEVJUIC compared to USDA Select ribeye steaks. However, PURCH ratings were higher (P = 0.0163) for USDA Select ribeye steaks than USDA Choice ribeye steaks. This is similar to information presented earlier on aged ribeye steaks, where USDA Choice ribeye steaks were rated higher (P < 0.05) for JUIC and LEVJUIC when compared to USDA Select ribeye steaks. Parrish et al. (1991) and Smith (2007) also found similar results. Table 14 presents the least squares means for palatability characteristics for baseline strip loin steaks. USDA Choice strip loin steaks rated significantly higher for level of beef flavor compared to USDA Select strip loin steaks. Although not significant, USDA Choice strip loin steaks had higher ratings than USDA Select strip loin steaks for the following characteristics: OLIKE, FLAV, JUIC, and LEVJUIC. Least squares means for palatability characteristics for baseline sirloin steaks are presented in Table 15. Even though no significant differences were found, USDA Select sirloin steaks rated higher for TEND, LEVTEND, and JUIC than USDA Choice sirloin steaks. These results contrast data found from ribeyes and strip loins in the present study. Also, this is quite contradictory to studies performed by Parrish et al. (1991) and Smith (2007) who found these attributes to be rated significantly higher for USDA Choice steaks than USDA Select steaks.

In Table 16, least squares means for cooking temperatures, cooking times, cooking yields, and WBS values are presented for baseline steaks from ribeyes, strip loins, and sirloins. The only significant difference is for cooking time among strip loin steaks. USDA Choice strip loin steaks had longer (P = 0.0367) cooking times than USDA Select strip loin steaks. Moreover, there is a trend amongst strip loin and sirloin steaks that cooking yield percentages are higher for USDA Choice steaks compared to USDA Select steaks. Baseline ribeye, strip loin, and sirloin steaks were cut to serve as a baseline for flavor and tenderness, however these were not analyzed with the other treatment combinations. By comparing the data in the aforementioned tables, trends may be deduced.

Retail Cutting Tests
Beef Rib, Ribeye Rolls, Lip-On, Bone In (Export Style) (similar to IMPS #109E), Beef Loin, Strip Loins, Bone In (similar to IMPS #175), and Beef Loin, Top Sirloin Butts, Boneless (similar to IMPS #184) and associated components from retail cutting tests were evaluated for average retail yields (Tables 17-22) and total cutting time (Table 23). For each subprimal, retail cuts (%) and cutting by-products (%) are tabulated displaying the comparisons of two different quality grades, USDA Choice and USDA Select, two different aging treatments, dry and wet aging, and four different aging periods, 14, 21, 28, and 35 d.

Interaction of USDA quality grade and aging period, and its effect on retail yield and by-product percentages of ribeyes are shown in Table 17. No significant differences were found; however, cooler shrink for USDA Choice and USDA Select ribeyes was highest at 35 d. Smith (2007) also found cooler shrink was highest (P > 0.05) at 35 d for both USDA Choice and USDA Select short loins. Also, cooler shrink and gross cut loss percentages increased with increased aging time for both USDA Choice and USDA Select ribeyes. Aging treatment x aging period is shown in Table 18 for ribeyes. Wet aged ribeyes for all aging periods produced a significantly higher percentage of ribeye steaks compared to dry aged ribeyes. 28 and 35 d dry aged ribeyes produced the lowest (P = 0.0023) percentage of ribeye steaks and had the highest (P = 0.0010) percentage of waste. 21 d and 35 d wet aged ribeyes had the lowest (P = 0.0010) percentage of waste when compared to other treatment and day combinations. Furthermore, 35 d dry aged ribeyes had the highest (P < 0.05) percentage of cooler shrink and gross cut loss, followed by 28, 21, and 14 d dry aged ribeyes, respectively for both. Wet aged ribeyes for all aging periods had a significantly higher total saleable yield than other aging periods within the dry aging treatment. This mirrors the Smith (2007) study in that the wet aged short loins for all four aging periods had significantly higher total saleable yield than their dry aged counterparts.

Least squares means of retail yield percentages for fabrication of strip loins stratified by USDA quality grade x aging period is shown in Table 19. USDA Choice, 14 d strip loins had the lowest (P = 0.0468) gross cut loss compared to other grade and aging day combinations. Although not significant, cooler shrink increased with each aging period for both USDA Choice and USDA Select strip loins, supporting the previous ribeye results. Table 20 presents aging treatment x aging period for strip loins. Interestingly, 28 d, dry aged strip loins displayed the highest (P = 0.0345) percentage of waste. Also, 28 and 35 d, dry aged strip loins possessed the highest (P < 0.0001) percentage of cooler shrink. All dry aged products had a greater (P < 0.05) amount of cooler shrink compared to their wet aged counterparts. This also supports ribeye results found in this study, as well as the study by Smith (2007). Furthermore, 28 and 35 d, dry aged strip loins had the highest (P < 0.0001) gross cut loss compared to other day and aging treatment combinations.

The interaction of USDA quality grade and aging period and its effect on retail yield and by-product percentages of sirloins is shown in Table 21. Although not significant, gross cut loss and cooler shrink percentages increased with increased aging times for both USDA Choice and USDA Select sirloins. This follows the same trend shown in the ribeye results. Also, the percentage of steaks from USDA Choice sirloins decreased as aging time increased. In Table 22, aging treatment x aging period is presented for sirloins. Similarly to the strip loin results, waste percentage is highest (P = 0.0212) for 28 d, dry aged sirloins. Furthermore, 35 d dry aged sirloins had the highest (P < 0.05) percentage of cooler shrink and gross cut loss, followed by 28, 21, and 14 d dry aged sirloins, respectively for both. These results mimic the aging treatment x aging period presented for ribeyes (Table 18). Moreover, 14 and 21 d, wet aged sirloins had the highest (P = 0.0011) percentage of total saleable yield. On the other hand, 28 and 35 d, dry aged sirloins had the significantly lowest percentage of total saleable yield. All wet aged product for ribeyes, strip loins, and sirloins resulted in higher (P < 0.05) percentages of total saleable yield when compared to their dry aged counterparts, which is identical to Smith (2007).

Effects of aging treatment, aging period, and USDA quality grade on total cutting times of ribeyes, strip loins, and sirloins are shown in Table 23. As expected, total processing time for dry aged products was greater (P < 0.0001) compared to wet aged products for all three subprimals. These results are supported through the research of Smith (2007). Dry aging will inevitably cause the surface tissue to dry out, creating what is referred to as waste or “scab.” This is undesirable and is trimmed away, causing increased fabrication times, and this excess time associated with processing dry aged product must be expected when producing dry aged product. Furthermore, aging period had a significant effect on the total cutting time for ribeyes and sirloins. 14 and 21 d ribeyes had a greater (P = 0.0005) amount of processing time compared to 28 and 35 d product. These results contradict research of Smith (2007), which found 28 and 35 d short loins to have greater processing times than 14 or 21d short loins. In the present study, 28 d sirloins required the shortest (P = 0.0199) processing time compared to other sirloin aging days. One significant interaction, aging day x USDA quality grade, was found for total cutting time of strip loins and is shown in Figure 6. 14 d USDA Choice strip loins took the greatest (P = 0.0021) amount of time to process. 14 and 28 d, USDA Select and 28 and 35 d USDA Choice strip loins had the shortest (P < 0.05) total cutting time when compared to other aging day and quality grade combinations.

IMPLICATIONS

WBS values and consumer ratings show wet aged ribeye steaks to be more tender than their dry aged counterparts. WBS values for ribeyes and sirloins decreased with increased aging time. Consumer ratings for tenderness like increased with increased aging time for all three subprimals. No significant differences were found for consumer evaluation of sirloins. Choice ribeye and strip steaks received higher consumer ratings for overall like and juiciness attributes when compared to Select steaks. Cutting tests were performed at the end of each aging period to determine retail yields and processing times. Retail cutting tests showed dry aged subprimals had lower total saleable yield percentages and increased processing times compared to wet aged subprimals. Cooler shrink and gross cut loss percentages increased with increased aging time for both Choice and Select subprimals.