Sensory Evaluation of Enhanced Beef Strip Loin Steaks Cooked to 3 Degrees of Doneness

The objective of this study was to evaluate the impact of marbling level in combination with enhancement on beef palatability when strip loin steaks were cooked to 3 degrees of doneness. Consumer and trained sensory panelists evaluated strip steak palatability traits of 3 USDA quality grades: Prime, Low Choice, and Low Select. Additional strip loins from each grade were enhanced to 108% with a water, salt, and alkaline phosphate solution. Steaks from each treatment were cooked to 3 degrees of doneness (DOD; Rare: 60°C, Medium: 71°C, or Very Well-Done: 82°C). Consumer panelists rated all enhanced treatments similar (P > 0.05) for each palatability trait. Enhanced steaks had greater (P < 0.05) juiciness, tenderness, flavor liking, and overall liking ratings than all non-enhanced treatments, regardless of grade. Consumer juiciness, tenderness, and overall liking scores increased (P < 0.05) as DOD decreased. Trained sensory panelists rated all enhanced treatments similar (P > 0.05) for initial and sustained juiciness, myofibrillar tenderness, and overall tenderness and greater (P < 0.05) than all nonenhanced treatments, other than non-enhanced Prime, for the same traits. Trained sensory panel ratings increased (P < 0.05) as DOD decreased for sustained juiciness, and both myofibrillar and overall tenderness. Moreover, Warner-Bratzler shear force values were similar (P > 0.05) among all enhanced treatments, and lower (P < 0.05) than non-enhanced Low Choice and Low Select treatments. Results from this study indicate marbling level has no impact on the palatability traits of enhanced strip loin steaks. Therefore, enhancement of higher valued, high marbled cuts does not provide additional palatability benefits over low marbled cuts, as enhancement does not provide an additive effect with marbling on beef eating quality.

with increased DOD (Parrish et al., 1973;Lorenzen et al., 2005;O'Quinn et al., 2015). However, a large percentage of beef consumers prefer steaks to be cooked to at least a medium DOD (Cox et al., 1997;Reicks et al., 2011). This indicates a need for beef to maintain a high level of eating quality, even at elevated DOD.
Enhancement technology has been shown to improve beef palatability, shear force values, and cooking loss (Baublits et al., 2006;Pietrasik and Janz, 2009;Brooks et al., 2010;Lucherk et al., 2016). Much of this previous research has focused on either lower palatability (tougher) muscles or lower quality grades (USDA Select or lower). Few studies have used higher quality grades of USDA Choice or Prime for enhancement. Additionally, research on cooking enhanced steaks to different degrees of doneness is limited. Therefore, the objective of this study was to determine the effect of enhancement on consumer and trained sensory panel palatability scores of 3 quality grades when cooked to 3 degrees of doneness.

Materials and Methods
The Kansas State University (KSU) Institutional Review Board approved the procedures used in this study (IRB 7440, November 21, 2014).

Experimental treatments and sample preparation
Beef strip loins [n = 72; IMPS #180; North American Meat Institute (2014)] were selected to equally represent 3 USDA quality grades: Prime, Low Choice (Small 00 -Small 100 ), and Low Select (Slight 00 -Slight 49 ) from a commercial beef processing plant in the Midwest. Strip loins were not paired, with each strip loin selected for the study collected from a separate carcass. Product was vacuum packaged and transported under refrigeration (2°C) to the KSU Meat Laboratory for further processing.
Following 14 d of aging, half (n = 12) of the strip loins within each quality grade were selected for enhancement. Strip loins designated for enhancement were enhanced with a solution formulated to result in 0.35% NaCl and 0.40% sodium phosphate (Brifisol 512, ICL Food Specialties, Saint Louis, MO) at a target 8% pump in the final injected product. Solution (pH = 8.09) was injected into product using a multineedle injector (Wolf-tec, IMAX 420 eco, Kingston, NY). Weights of strip loins were recorded before and 15 min after injection for calculation of actual percentage pump (6.91 ± 1.42%). Enhanced loins were then vacuum packaged and held at 2 to 4°C for an additional 7 d. Strip loins not designated for enhancement were aged for the full 21 d under vacuum at 2 to 4°C.
At the end of the 21 d aging period, strip loins were fabricated into 2.5-cm thick steaks. The most anterior (wedge) steak was removed and used to obtain measurements of instrumental color (L*, a*, b*), pH, and proximate analysis. Immediately following slicing, the freshly cut surface of the wedge steak was allowed to bloom for 15 min prior to color measurement using a Hunter Lab Miniscan spectrophotometer (Illuminant A, 2.54-cm aperture, 10° observer; Hunter Associates Laboratory, Reston, VA). Scans were taken at 3 locations on each steak and the readings were averaged for L*, a*, and b* values. The pH was measured once for each steak using a pH meter (model HI 99163;Hanna Instruments,Smithfield,RI). After readings were collected, wedge steaks were packaged and frozen at -20°C for proximate analysis.
Each strip loin was designated into thirds (from anterior to posterior), with each third assigned to 1 of the 3 DOD (Rare: 60°C; Medium: 71°C; or Very Well-Done: 82°C) in a balanced design. Within each section, four 2.5-cm thick steaks were cut, with one steak randomly assigned to each of: consumer panel, trained panel, objective measurements, or flavor analysis (data not reported). Steak assignment was balanced across all strip loins in each treatment. All steaks were weighed fresh, identified with a unique four digit number, and were vacuum packaged individually and frozen at -20°C.

Consumer panel evaluation
Panelists (n = 252) were recruited from Manhattan, KS and the surrounding communities and monetarily compensated for participation. Consumer panels were conducted at the KSU Meat Science Sensory Laboratory. Each panelist was placed in individual sensory booths and samples were served under low intensity (< 107.64 lumens) red incandescent lighting used to mask DOD variations among samples. A total of 36 panels were conducted with 7 consumers per session and lasted approximately 1 h.
Panelists were provided with a ballot, toothpick, napkin, fork, knife, water cup, expectorant cup, unsalted crackers, and apple juice which were used as palate cleansers between samples. Each ballot contained an informational sheet, a demographic questionnaire, and survey ballots for each sample to be evaluated. Prior to the start of each panel, verbal instructions were given to consumers about how to fill out the ballot sheets and the testing procedures. Steaks were thawed (2 to 4°C) 24 h prior to evaluation. A thaw weight was recorded for determination of the percentage of thaw loss and remaining external fat and accessory muscles (M. multifidus dorsi and M. gluteus medius) were removed prior to cooking and weighing for cook loss evaluation. Steaks were cooked to the preassigned DOD [Rare (60°C), Medium (71°C), or Very Well-Done (82°C)] on a clamshell grill (Cuisinart Griddler Deluxe, East Windsor, NJ). Thermocouples (30-gauge copper and constantan; Omega Engineering, Stamford, CT) monitored temperatures with a Doric Mini-trend Data Logger (Model 205 B-1-c OFT, Doric Scientific, San Diego, CA) and peak temperatures were verified with a probe thermometer (Model 450-ATT, Omega Engineering, Stamford, CT). Following a 2 min rest period, steaks were cut into 1.3-cm by 1.3-cm by 2.54-cm cubes. Two cubes were immediately served to 7 consumers, with 6 samples served per panel representing multiple DOD and quality treatments. The study was designed as a partially balanced, incomplete block design so that every quality treatment × DOD combination was compared as close to an equal number of times as possible across all 36 panel sessions. This was done to allow for consumers to evaluate multiple degrees of doneness and quality treatments within the same panel session. Prior to evaluation, panelists were asked to rate a list of 15 beef purchasing motivators in terms of importance with anchors located at 0 mm and 100 mm. The 0 mm anchor was labeled as extremely unimportant and 100 mm was labeled as extremely important. Additionally, panelists rated each sample for the traits of juiciness, tenderness, flavor liking, and overall liking on 100-mm line scales. Anchors were located at 0 mm and 100 mm, with 0 mm labeled as extremely dry, extremely tough, and extremely dislike; and 100 mm labeled as extremely juicy, extremely tender, and like extremely. Each scale also had a midpoint at 50 mm labeled as neither dry nor juicy, neither tough nor tender, and neither dislike nor like. Finally, consumers rated each trait evaluated as either acceptable or unacceptable and also classified samples into 1 of 4 quality levels: unsatisfactory, everyday quality, better than everyday quality, or premium quality.

Trained panel evaluation
Training of panelists and taste matching tests were performed using the protocols described by the Research guidelines for cookery, sensory evaluation, and instrumental tenderness measurements of meat (American Meat Science Association, 1995). Ten sensory training sessions were held in the 3 wk prior to starting the trained sensory panels. Additionally, training references and an-chors were consistent with those described by Lucherk et al. (2016) and Adhikari et al. (2011). Steaks were prepared as described previously for consumer panel evaluation. A total of 36 panel sessions were conducted by an 8-member trained panel. Steaks were cut into 1.3-cm by 1.3-cm cubes and placed into double broilers, and held on a stove top (Model AKC-35D, Amana Corporation, Newton, IA) at 43°C for no more than 15 min prior to sample evaluation. A warmup sample was served to panelists prior to evaluation of treatment samples.
Panelists were given an electronic tablet (Model 5709 HP Steam 7; Hewlett-Packard, Palo Alto, CA), toothpick, napkin, fork, knife, water cup, expectorant cup, and unsalted crackers and sliced apples which were used as palate cleansers between samples. Panelists were served in individual sensory booths at the KSU Meat Science Sensory Laboratory. Samples were served under low intensity (< 107.64 lumens) red incandescent lighting used to mask DOD variations among samples. Samples were rated on digital ballots designed through the Qualtrics survey software (Version 2417833). Each sample was evaluated for initial juiciness, sustained juiciness, myofibrillar tenderness, amount of connective tissue, overall tenderness, beef flavor intensity, salt flavor intensity, off-flavor intensity, and panelists were asked to describe any off-flavor detected. The traits were rated on continuous line scales. The 0 anchors were labeled as extremely dry, extremely tough, none, and extremely bland; and the 100 anchors were labeled as extremely juicy, extremely tender, abundant, and extremely intense. Midpoint (50%) anchors for initial juiciness, sustained juiciness, myofibrillar tenderness, and overall tenderness were labeled as neither dry nor juicy, and neither tough nor tender. Also, there were boxes labeled "not applicable" to check for salt intensity and off flavor intensity for samples where none were detected.

Slice shear force and Pressed Juice Percentage
The protocol followed for Slice Shear Force (SSF) is described by Shackelford et al. (1999) and was performed using a shearing machine (Model GR-152, G-R Manufacturing Co., Manhattan, KS) with a crosshead speed of 500 mm/min, and a basic force gauge (BFG500N, Mecmesin Ltd., West Sussex, UK) which was attached to a SSF blade to measure peak force (kg) required to shear through the warm slice. The Pressed Juice Percentage (PJP) protocol used is described by Lucherk et al. (2017). Pressed Juice Percentage samples were weighed on 2 pieces of filter paper (VWR Filter Paper 415, 12.5 cm, VWR International, Radnor, PA) and compressed for 30 s at 78.45 N of pressure using an INSTRON Model 5569 testing machine (Instron, Canton, MA). The three sample values were averaged for a single PJP value for each steak.

Warner-Bratzler shear force
After PJP and SSF sample removal, steaks were cooled for 12 h at 2-4°C prior to Warner-Bratzler shear force (WBSF) analysis (American Meat Science Association, 1995). Six cores (1.27-cm diameter) were removed parallel to the muscle fiber orientation and sheared using an INSTRON Model 5569 testing machine (Instron, Canton, MA) set to a crosshead speed of 250 mm/min, with a WBSF (V-notch) blade attached. The peak force (kg) required to shear each core was recorded and the 6 values were averaged for a single WBSF value for each steak.

Proximate analysis
All exterior fat and accessory muscles (M. multifidus dorsi and M. gluteus medius) were removed from the M. longissimus dorsi of each sample for proximate analysis. Samples were submerged in liquid nitrogen and homogenized using a commercial 4 blade blender (Model 33BL 79, Waring Products, New Hartford, CT). Powdered samples were then placed in Whirl-Pac (Nasco, Fort Atkinson, WI) bags and stored (-20°C) until further analysis. The procedures followed for lipid extraction are described by Martin et al. (2013). Moisture content was determined using an oven drying method (AOAC, 2005). Nitrogen content was determined using a combustion method (TruMac N Nitrogen/Protein determination Instruction manual, 2014, Leco Corp., St. Joseph, MI) and multiplied by 6.25 to determine protein content. A muffle furnace was used to determine percent ash following the AOAC ash oven method (AOAC, 2005).

Statistical analysis
For this study, quality treatment was defined as the USDA quality grade/enhancement level combination, so that there were a total of 6 quality treatments (1 enhanced and 1 non-enhanced treatment from each quality grade). This was done to allow for the comparison of means across all 6 quality treatments to best accomplish the study objectives and demonstrate the impact of enhancement on each of the quality grades. SAS (Version 9.4; SAS Inst. Inc., Cary, NC) was used for statistical analyses. Comparisons among treatment means were evaluated for significance using PROC GLIMMIX with ɑ = 0.05. All sensory panel and objective data were analyzed as a split-plot arrangement of factors. The model included the whole-plot factor of quality treatment and the sub-plot factors of DOD and the quality treatment × DOD interaction. For sensory data, panel session number was included as a random effect. All consumer acceptability data were compiled as the proportion of "acceptable" responses within each steak and the data were analyzed with a model that included a binomial error distribution using PROC GLIMMIX. All color, pH, and proximate data were analyzed with a model that included the fixed effect of quality treatment. For all analyses, the Kenward-Roger approximation was utilized for estimation of denominator degrees of freedom and the PDIFF option was used to separate treatment means when the F-test on the overall effect was significant (P < 0.05). The quality treatment × DOD interaction was nonsignificant (P > 0.05) for all dependent variables, unless otherwise denoted. For significant interactions, the SLICE option of the LS MEANS statement was used to restrict comparisons among quality treatments to within the same degree of doneness.

Proximate composition and objective measures
Instrumental color readings, pH values, and percentages of chemical moisture, protein, fat, and ash are presented in Table 1. Enhanced treatments were all similar (P > 0.05) for pH and had a higher (P < 0.05) pH than all non-enhanced treatments. Moreover, fat percentage increased (P < 0.05) with increased USDA quality grade in both enhanced and non-enhanced treatments. Moisture content was inversely related (P < 0.01) to fat percentage (r = -0.75). Consequently, Prime samples had the lowest (P < 0.05) moisture content in both enhanced and non-enhanced treatment groups. It is noteworthy that enhancement resulted in only numerical increases in moisture content for samples from each quality grade, however no statistical differences (P > 0.05) were found between enhanced and non-enhanced samples of the same quality grade. Instrumental color readings indicated L* values increased (P < 0.05) as quality grade increased in the enhanced and non-enhanced samples ( Table 2). The L* values of the non-enhanced Low Choice and Low Select samples were higher (P < 0.05) than their enhanced counterparts, and no differences (P > 0.05) were found for a* and b* values among non-enhanced Strip Steaks at 3 Degrees of Doneness American Meat Science Association.
www.meatandmusclebiology.com treatments. Enhanced and non-enhanced Prime samples were similar (P > 0.05) for both a* and b* values and Low Choice samples only had lower (P < 0.05) b* values as a result of enhancement. Table 1 contains results from objective juiciness and tenderness measurements. Objective measures of tenderness (WBSF and SSF) showed similar results, with non-enhanced Low Select samples determined to be the toughest (P < 0.05) of all treatment groups and non-enhanced Prime and Low Choice to be similar (P > 0.05) for tenderness. However, WBSF indicated non-enhanced Low Choice samples were tougher (P < 0.05) than all enhanced treatments. Conversely, SSF indicated a similar (P > 0.05) tenderness among all enhanced treatments and non-enhanced Prime and Low Choice samples. No difference (P > 0.05) in SSF value was found among DOD treatments. Additionally, WBSF was similar (P > 0.05) between Medium and Very Well-Done samples, with Rare samples being more tender (P < 0.05) than either.
The percentages of cooking loss, thaw loss, and total (initial raw weight -cooked weight) loss for steaks used for consumer and trained panels are reported in Table 1. The percentage of cooking loss was lower (P < 0.05) for all enhanced treatments when compared to non-enhanced treatments. Percentages of thaw loss decreased (P < 0.05) for non-enhanced consumer steaks as quality grade increased. Overall, percentages of thaw loss tended to be lower for enhanced treatments when compared to non-enhanced treatments. When comparing steaks cooked to different DOD, it is not surprising that the amount of cooking loss increased (P < 0.05) as DOD increased from Rare to Very Well-Done. Rare samples had close to half the amount of weight lost as a result of cooking compared to Very Well-Done steaks in the current study. The total loss and cooking loss for enhanced treatments were similar (P > 0.05) and lower (P < 0.05) than the non-enhanced treatments for trained and consumer panel steaks.

Consumer demographics
The demographic profile of the 252 consumers who participated in the consumer sensory analysis are presented in Table 3. Participants were primarily Caucasian/White (87.76%) from a household size of at least three people (61.69%), and at least 30 yr of age (45.13%). The number of males (60%) was greater than females (40%), with close to half (47.58%) of participants married. Most consumers (47.11%) had completed some college/technical school or were college graduates (22.31%). Within the group of participants, 51.21% consumed beef at least 4 times a wk and 65.87% reported their preferred degree of doneness to be mediumrare or medium. Also, beef was chosen as the product preferred for flavor by a large majority (70.56%) of consumers, more than 8 times higher than chicken (8.06%), or pork (7.26%). When asked what palatability trait was most important when eating beef, flavor was chosen by nearly half (49.90%) of the consumers, followed by tenderness (36.55%), and juiciness (14.06%). Table 4 contains least squares means of consumer ratings of palatability traits. In non-enhanced samples, Prime and Low Choice were similar (P > 0.05) for all palatability traits and higher (P < 0.05) for juiciness and tenderness than Low Select samples. Moreover, non-enhanced Low Choice samples were similar (P > 0.05) to non-enhanced Low Select samples for flavor and overall liking. All enhanced treatments, regardless of quality grade, were similar (P > 0.05) for all palatability traits evaluated. Additionally, enhanced treatments had greater (P < 0.05) ratings of juiciness, tenderness, flavor liking, and overall liking than all non-enhanced treatments.

Consumer sensory evaluation
A higher (P < 0.05) percentage of samples from each enhanced treatment were rated acceptable for juiciness, tenderness, flavor liking, and overall liking than all nonenhanced samples, except for non-enhanced Prime samples for juiciness, tenderness, and overall liking (Table 5). Additionally, no difference (P > 0.05) was found among all enhanced treatments for the percentage of samples rated acceptable for all palatability traits, with each trait having more than 85% of samples rated acceptable. No difference (P > 0.05) was found between non-enhanced Prime and Low Choice samples for the percentage of samples rated acceptable for all palatability traits. Additionally, non-enhanced Low Select samples were rated unacceptable overall more (P < 0.05) than all other treatments for each palatability trait, with more than 40% of samples rated unacceptable overall. A smaller (P < 0.05) percentage of Prime and Low Choice enhanced samples were classified as unsatisfactory quality and a greater (P < 0.05) percentage of enhanced samples were identified as better than everyday quality and premium quality than all non-enhanced treatments (Table 6). There was no difference (P > 0.05) between non-enhanced Prime and Low Choice samples for the percentage of samples rated unsatisfactory and better than everyday quality. Also, all non-enhanced samples were similar (P > 0.05) in the percentage classified as premium quality. When cooked to Rare and Medium, a smaller (P < 0.05) percentage of enhanced samples of each treatment were classified as everyday quality than non-enhanced samples (Table 7). Whereas when cooked to Very Well-Done, no difference (P > 0.05) among treatments was found for the percentage of samples identified as everyday quality. When evaluating consumer ratings for steaks differing by DOD, juiciness, tenderness, and overall liking scores increased (P < 0.05) as DOD decreased (Rare > Medium > Very Well-Done; Table 4). Moreover, Rare samples were rated higher (P < 0.05) for flavor liking than Medium or Very Well-Done samples. Similar results were found in the percentage of samples rated acceptable for each palatability trait,  a-c Least squares means in the same section of the same column without a common superscript differ (P < 0.05).
2 Enhanced to 108% of raw weight with a water, salt, and alkaline phosphate solution.
3 SE (largest) of the least squares means. American Meat Science Association. www.meatandmusclebiology.com with a greater (P < 0.05) number of samples rated acceptable for juiciness, tenderness, and overall liking as DOD decreased from Very Well-Done to Medium to Rare (Table 5). Additionally, more (P < 0.05) Rare samples were rated acceptable for flavor liking than Very Well-Done samples. A greater (P < 0.05) percentage of Very Well-Done samples were identified as unsatisfactory quality than Medium or Rare samples (Table  6). Moreover, a higher (P < 0.05) percentage of Rare samples were classified as better than everyday quality than Medium and Very Well-Done samples and a lower (P < 0.05) percentage of Very Well-Done samples were rated as premium quality than Rare or Medium samples.

Trained sensory panel evaluation
A quality treatment × DOD interaction was found for initial juiciness (P < 0.05; Table 7). Regardless of quality treatment, initial juiciness scores increased (P < 0.05) as DOD decreased (Rare > Medium > Very Well-Done). Across all three DOD, all enhanced samples were similar (P > 0.05) for initial juiciness. Moreover, non-enhanced Prime was similar (P > 0.05) to all enhanced treatments when cooked to Rare, but was drier (P < 0.05) than enhanced Prime samples at Medium and Very Well-Done degrees of doneness. Within non-enhanced treatments, initial juiciness increased (P < 0.05) with increased marbling scores (Prime > Low Choice > Low Select) when cooked to Medium, however, Prime was similar (P > 0.05) to Low Choice in Rare samples, and Low Choice was similar (P > 0.05) to Low Select when samples were cooked to Very Well-Done.
Trained panel ratings for all other sensory traits are presented in Table 8. Similar to initial juiciness, no difference (P > 0.05) was found among all enhanced treatments, regardless of quality grade for sustained juiciness. Non-enhanced Prime samples were similar to enhanced Low Choice and Low Select samples for sustained juiciness, but juicier (P < 0.05) than nonenhanced Low Choice and Low Select samples, with non-enhanced Low Choice samples rated juicier (P < 0.05) than non-enhanced Low Select samples. When evaluating measures of tenderness, no differences (P > 0.05) were found among enhanced treatments for over-  a-c Least squares means in the same section of the same column without a common superscript differ (P < 0.05).
1 Enhanced to 108% of raw weight with a water, salt, and alkaline phosphate solution.
2 SE (largest) of the least squares means.
all and myofibrillar tenderness. Also, non-enhanced Low Select samples were tougher (P < 0.05) overall and tougher for myofibrillar tenderness than all other treatments. Little variation in connective tissue amount was found among treatments, with only non-enhanced Low Select samples having a greater (P < 0.05) amount of connective tissue than all other treatments.
Beef flavor intensity increased (P < 0.05) with increased marbling level in non-enhanced samples. Additionally, both enhanced and non-enhanced Prime samples had a more (P < 0.05) intense beef flavor than all other treatments. As was expected, all enhanced treatments had a greater (P < 0.05) salt intensity than all non-enhanced treatments, with close to no salt flavor (< 0.14 units) observed in the non-enhanced samples. Despite all enhanced products having a similar salt content, the salt flavor intensity rating decreased (P < 0.05) as the quality grade increased. Differences were observed among treatments for off-flavor presence, however only a low amount (< 6 units) of offflavor was observed within any treatment group.
When comparing different degrees of doneness, initial juiciness, sustained juiciness, myofibrillar tenderness, and overall tenderness all decreased (P < 0.05) as DOD increased (Rare > Medium > Very Well-Done). No difference (P > 0.05) was found among DOD for connective tissue amount, beef intensity, or off-flavor intensity scores. However, Very Well-Done samples were rated higher (P < 0.05) for beef flavor identity than Rare and Medium samples.

Objective measures
Fat percentages in our study are slightly lower than those reported in previous studies evaluating beef of the same quality grades (Savell et al., 1986;O'Quinn et al., 2012;Emerson et al., 2013;Legako et al., 2015). In these studies, the authors used either NIR, ether extraction, or Foltch methodology to quantify fat percentage. In the current study, a modified chloroform/methanol extraction protocol described by Martin et al. (2013) was used for fat quantification. This methodological difference may explain the differences between fat percentages observed in the current study and the values reported by previous authors. However, the results of the current study are consis-tent with authors who have used CEM to quantify the fat percentage of beef of different quality grades (Dow et al., 2011) and show a similar increase in fat percentage and the same relative differences among quality grades for fat percentage as in previous reports.
Studies by Pietrasik and Janz (2009) and Baublits et al. (2006) determined steaks enhanced to 112 to 125% of the raw weight had between 2.97 and 3.30% increase in moisture percentage from non-enhanced controls. However, in the current study steaks were enhanced to 108% and no such increase in moisture percentage was observed. Similar to our results, Stetzer et al. (2008) and Smith et al. (1984) reported no difference in enhanced and non-enhanced steaks moisture content when steaks were enhanced to 108 and 110%, respectively. Additionally, Lucherk et al. (2016) reported Select steaks enhanced to 107% did not differ in moisture content from non-enhanced Select steaks; however, Select steaks enhanced to 112% had a 2.77% increased moisture percentage compared to non-enhanced Select steaks in that study. Collectively these studies indicate for differences to be detected in the percentage of chemical moisture of a-d Least squares means in the same section of the same column without a common superscript differ (P < 0.05).
2 Enhanced to 108% of raw weight with a water, salt, and alkaline phosphate solution.
3 SE (largest) of the least squares means. 4 P-value for main effect of quality treatment.  raw samples, enhanced treatments typically require greater than a 10% pump level. Increased muscle pH as a result of alkaline phosphate enhancement have been previously observed by authors, with increases in pH of 2.90, 2.10, and 7.50% previously reported by Robbins et al. (2003b), Baublits et al. (2006), and Wicklund et al. (2005), respectively. Our study reported pH increases of 2.90 to 3.41% for enhanced treatments. Additionally, Robbins et al. (2003b) found when enhancing beef strip loins with a solution similar to the current study (water, salt, and alkaline phosphates) L* readings of enhanced strip loins were darker (3.91 to 7.93% lower) than non-enhanced control samples. Robbins et al. (2003b) also reported enhanced treatments had 9.09 to 14.38% and 5.69 to 11.19% lower a* and b* values, respectively, than non-enhanced counterparts. Similarly, Wicklund et al. (2005) reported enhanced steaks had lower values of L* by 9.89%, a* by 9.67%, and b* by 17.41% than a non-enhanced control treatment. The current study reported comparable results to previous research, as the enhanced treatments had a 5.43 to 8.18% decrease for L* value. Also, decreases of 6.99% in a* values for enhanced Low Select, and 9.56 to 10.69% decreases in b* values for enhanced Low Choice and Low Select were observed when compared to the non-enhanced treatments. Collectively, these studies indicate enhancement with salt and alkaline phosphate solutions result in darker lean color with lower a* and b* values. This is important as color has been reported as the most influential factor affecting consumer purchasing decisions within the marketplace, with consumers preferring steaks that are bright cherry-red colored rather than dark or dull red in color (Mancini and Hunt, 2005). Robbins et al. (2002), Stetzer et al. (2008), andWicklund et al. (2005) used trained sensory panelists to evaluate visual color and found results similar to the instrumental color scores reported in the current and previous studies. Though, to date, no studies have evaluated consumer acceptance of the color of enhanced beef. Cox et al. (1997) determined when consumers were served a different DOD than what was ordered at a restaurant, consumer palatability scores decreased, which helps to demonstrate the large role DOD plays in the consumer eating experience. Multiple studies have prescreened consumers and fed only a single, preferred DOD Lucherk et al., 2016); however, this often limits the ability to make meaningful comparisons and conclusions across different DOD within the same study. Moreover, other authors have had consumers evaluate steaks of differing DOD under white lighting (Gomes et al., 2014), though this is not recommended (American Meat Science Association, 1995) due to the inherent consumer bias due to DOD preference described by Cox et al. (1997). In our study, similar to Cross et al. (1976) and Parrish et al. (1973), panelists evaluated samples from multiple DOD under red lighting to mask the DOD appearance differences among samples. This was done to allow for consumers to evaluate samples of varying DOD without an inherent bias due to product appearance. Our study reports Rare was rated the most juicy, tender, flavorful, and the highest liked by consumers. Whereas, based on the demographic profile, Rare was the preferred DOD by only 4.42% of consumers, providing evidence that consumer DOD preference did not create a bias within this study. Conversely, the study by Gomes et al. (2014) reported the appearance of cooked samples (under white lighting) influenced consumer sensory ratings as they were asked to rate the internal red and brown color prior to sensory evaluation, thus limiting the ability to make unbiased comparisons among DOD treatments.

Degree of doneness
Many studies have reported as DOD increases, palatability ratings of juiciness and tenderness decrease (Cross et al., 1976;Savell et al., 1999;Lorenzen et al., 2005;Gomes et al., 2014;Lucherk et al., 2016). Juiciness ratings have been shown to have dramatic decreases (16 to 70%) when DOD was increased from lower endpoint temperatures (55 to 60°C) to higher endpoint temperatures (77 to 90°C) in multiple studies (Parrish et al., 1973;Cross et al., 1976;Lorenzen et al., 2005;Lucherk et al., 2016). Observed tenderness decreases have been similar, with decreased tenderness ratings of 20 to 58% when final endpoint temperature is increased over the same range (Parrish et al., 1973;Cross et al., 1976;Lorenzen et al., 2005). The current study shows a decrease in palatability similar to previous research. As final internal temperature increased from 60°C to 82°C, tenderness and juiciness decreased 22.51 and 36.55%, respectively.
Moreover, the importance of final endpoint temperature and the resulting dehydration of samples due to cooking loss at elevated DOD on beef tenderness is evident. Many authors have reported as DOD increases, WBSF values also increase (Lorenzen et al., 2005;Gomes et al., 2014;Lucherk et al., 2016). It is also well documented that as internal temperature increases, the percentage of cooking loss increases (Parrish et al., 1973;Luchak et al., 1998;Lorenzen et al., 2005). Our results mimic those of previous studies, with increased moisture loss as a result of cooking increasing with increased DOD. However, few differences in shear force values were observed, as the Rare samples had the lowest WBSF values, but Medium and Very-Well Done were similar. Moreover, no differences among DOD were found for SSF. These findings may be attributed to the high level of tenderness (all < 13.2 kg) found among these treatments, likely due in part to the 21 d aging period used in the current study.

Quality treatment
Previous studies evaluating enhancement have focused on either lower palatability muscles or enhancing lower quality grades such as USDA Select. Prior research has found that enhancement increased consumer sensory scores for tenderness, juiciness, flavor liking, and overall liking of USDA Select beef (Miller et al., 1995;Brooks et al., 2010;Igo et al., 2015). The current study agrees with theses previous findings for the Low Select enhanced treatment. Previous studies reported enhancement of steaks resulted in a 11.54 to 35.50% increase in tenderness (Brooks et al., 2010;Igo et al., 2015;Lucherk et al., 2016), and the current study found a 30.21% increase from nonenhanced Low Select to the enhanced counterpart. Additionally, prior research reported enhanced steaks had an increase of 10.53 to 28.26% in consumer juiciness scores, and the current study reported a 30.60% increase (Brooks et al., 2010;Igo et al., 2015;Lucherk et al., 2016). An increase in flavor liking was also reported for enhanced steaks of 5.00 to 28.36% in previous research (Brooks et al., 2010;Igo et al., 2015;Lucherk et al., 2016), with the current study reporting a 27.98% increase for the Low Select enhanced treatment over the non-enhanced Low Select. The current study also reported a 27.33% increase in overall liking for the enhanced Low Select over the non-enhanced counterpart, with similar increases (10.39 to 33.12%) in overall liking observed in previous studies (Brooks et al., 2010;Igo et al., 2015;Lucherk et al., 2016).
However, research has not previously evaluated the enhancement of higher quality cuts. Our study enhanced a range of quality grades, and found that all enhanced treatments were similar, regardless of the marbling level. As quality grade increased the percentage increase in all palatability traits decreased. Our study reported consumer ratings of tenderness increased for enhanced treatments by 30.21% for Low Select, 16.88% for Low Choice, and 10.61% for Prime. Ratings for juiciness were 30.60, 19.44, and 11.92% higher for the enhanced Low Select, Low Choice, and Prime, respectively. Flavor liking was rated greater for the enhanced samples by 27.98% for Low Select, 22.06% for Low Choice, and 17.13% for Prime. Also, overall liking was reported to increase with enhancement, with Low Select increasing 27.33%, Low Choice increasing 23.50%, and Prime increasing 17.28%. Therefore, enhancement has a large positive impact on beef palatability; however, improvement potential is not independent of or additive with quality grade. This demonstrates a more limited benefit to enhancing higher quality beef and indicates the most appropriate use of enhancement technology remains in lower quality beef cuts.
Additionally, enhanced beef has been reported as having a greater salt flavor and greater beef flavor than similar non-enhanced beef products (Robbins et al., 2003a;Pietrasik and Janz, 2009). In the current study, trained panelists indicated an increase in salt intensity in enhanced samples. However, there was an increase in salt intensity among enhanced samples as the quality grade decreased. This dilution effect of salt flavor may be the result of the increased fat percentages of the higher quality grades, perhaps providing some overshadowing effect of the salt flavor due to the increase in beef flavor intensity observed with the higher quality grades.
Previous research indicates as quality grade increases, the palatability traits of juiciness, flavor, and tenderness increase for consumer and trained panelists (Neely et al., 1998;Acheson et al., 2014;Corbin et al., 2015). Furthermore, prior research indicates that as quality grade increases, the percentage of samples rated acceptable by consumers for all palatability traits also increases (Behrends et al., 2005;Corbin et al., 2015;Tatum, 2015;O'Quinn, 2016). In the current study, though differences were found, quality grade did not have as large of an effect as reported in previous studies. Non-enhanced Prime and Low Choice were found to be similar in all consumer panel ratings. The range of palatability traits in samples consumers evaluated in our study was extremely large. Both enhanced and non-enhanced samples of the three quality grades cooked to multiple DOD were served during the same panel sessions. It is possible that DOD and enhancement effects had a greater influence on consumer eating quality than quality grade in the current study, allowing for fewer differences among quality grades to be found than in previous reports that evaluated samples within the same degree of doneness and did not include enhanced samples.
Within the current study it is important to note that with consumer data, no difference was found in palatability ratings, acceptability, or perceived quality levels among the enhanced treatments, regardless of quality grade. Additionally, the enhanced treatments were all similar in acceptability to the non-enhanced Prime treatment. Thus, a consumer eating a Low Select en-American Meat Science Association.
www.meatandmusclebiology.com hanced steak would receive a similar eating experience as a Prime steak. However, there is currently a $13.69/ kg premium for Prime strip loins over Select (USDA, 2017a(USDA, , 2017b. Therefore, a similar eating experience can be attained without the premiums required for the higher quality grade. Additionally, it is notable that in the current study, enhancing the high quality graded cuts did not result in proportional increases in eating quality. This indicates enhancement does not provide an additive effect with quality level for beef palatability. It appears that enhancement improves the palatability of strip loins to a constant level, regardless of product initial quality grade or palatability level. These results give clear evidence that enhancement of higher grading beef (Choice and Prime) is not financially advantageous to producers, as no added benefit is gained when compared to enhancement of lower grading beef. However, these results also indicate the large opportunity for beef eating quality improvement of Select beef through the use of enhancement technology.