JFS S: Sensory and Food Quality. S: Sensory & Food Quality. Introduction The meat industry is constantly working to satisfy consumer

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1 JFS S: Sensory and Food Changes in Beef Complexus, Serratus Ventralis, Vastus Lateralis, Vastus Medialis, and Longissimus Dorsi Muscles Enhanced Prior to Aging A.J. STETZER, E. TUCKER,F.K.MCKEITH, AND M.S. BREWER ABSTRACT: Beef complexus (chuck), serratus ventralis (chuck), vastus lateralis (round), vatsus medialis (round), and longissimus dorsi (loin) muscles were enhanced (0.3% salt, 0.4% phosphate), vacuum packaged, and aged for 7 or 14 d. Enhancement increased positive sensory attributes (tenderness, juiciness, beef flavor, saltiness) and decreased negative attributes (off-flavors) of all muscles but had greater effects on some than on others. It increased the oily mouthfeel (10%) and saltiness (40%) and decreased the L* value and chroma of the complexus (chuck). It increased tenderness, juiciness, and beef flavor and decreased off-flavors, visual red and brown colors, shear value, and cook loss of the serratus ventrali (chuck), vastus lateralis (round), vastus medialis (round), and longissiumus dorsi (loin). Aging slightly decreased rancid and liver off-flavor scores, visual brown color, and shear value and increased the hue angle and L*andb*values. Keywords: aging, beef, enhancement, muscles, quality Introduction The meat industry is constantly working to satisfy consumer expectations for dependable, high-quality meat products at a reasonable cost to producers, processors, and retailers. Based on the Natl. Beef Audit, tenderness is a primary concern of beef retailers. In 1999, approximately 72% of strip loins purchased from supermarkets in 8 major U.S. cities were rated as only slightly tender to moderately tender by consumers (George and others 1999). It is vital that a commercially feasible method be developed to assure consistently tender products with acceptable flavor (Kerth and others 1995; Robbins and others 2003a, 2003b). Postmortem biochemical changes dramatically affect tenderness. Zamora and others (1996) reported that toughness is negatively correlated with initial ph and rate of ph decline. Aging increases tenderness (Wicklund and others 2005); however, it also results in flavor changes (Bauer 1983; Kato and Nishimura 1987). Spanier and others (1997) reported that aging increases bitter and sour off-flavors and decreases desirable beefy, brothy, brownedcaramel, and sweet flavors. Gorraiz and others (2002) reported that beef from bulls had a stronger liver-like aroma and flavor, and bloody flavor, while beef from heifers had more beef flavor. Aging increased these characteristic flavors. Beef flavor results from the combination of basic tastes (sweet, sour, bitter, salt, umami) and odor derived from volatile compounds (MacLeod 1994). Oxidation of unsaturated fatty acids typically produces a variety of compounds, some of which give the characteristic odors to specific types of meat. However, other compounds may contribute noticeable off-flavors. Injection technology for improving the sensory quality of poultry has been in place for many years (Grey and others 1978; Griffiths MS Submitted 2/5/2007, Accepted 9/30/2007. Authors Stetzer, Tucker, and Brewer are with Dept. of Food Science and Human Nutrition, Univ. of Illinois, 208 ABL, 1302 W. Pennsylvania, Urbana, IL 61801, U.S.A. Author McKeith is with Dept. of Animal Science, Univ. of Illinois, 208 ABL, 1 Urbana, IL 61801, U.S.A. Direct inquiries to author Brewer ( msbrewer@uiuc.edu). and Wilkinson 1978). More recently, the pork industry has taken advantage of injection technology to improve sensory attributes of case ready loins (Sheard and others 1999; Brewer and others 2002; Prestat and others 2002). Enhancing beef strip steaks and clod roasts increased tenderness and juiciness and decreased Warner Bratzler shear values (Vote and others 2000; Robbins and others 2003a, 2003b; Baublits and others 2005a; Wicklund and others 2005). Robbins and others (2003a) reported that in a cook/hothold situation, enhanced beef had more intense beef flavor and less off-taste and beany/grassy aroma than nonenhanced beef. These results suggest that enhancement may modulate flavor and aroma changes that occur during aging. Wicklund and others (2005) reported that when beef loins were enhanced prior to aging, an agingperiodof7to14dproducedsteaksthatwereastenderas those aged 28 d prior to enhancement. Enhancement prior to aging may be the most advantageous approach. In addition, consumer acceptance of enhanced products is becoming more widespread (Robbins and others 2003b). The objectives of this study were to evaluate the effects of enhancement and aging on quality characteristics of beef complexus, serratus ventralis, vastus lateralis, vastus medialis, andlongissimus dorsi muscles. Materials and Methods Sample manufacture Twenty USDA Select heifer carcasses from cattle with commercial genetic backgrounds were obtained from a commercial supplier. Slaughter weights ranged from 270 to 320 kg. Carcass identity was maintained throughout the study. The complexus (chuck), serratus ventralis (chuck), vastus lateralis (round), vatsus medialis (round), and longissimus dorsi (loin) were removed 48 h after slaughter. Muscles from 1 side of each carcass were used as the nonenhanced control. Muscles from the remaining side were enhanced (108% of original weight) to contain 0.4% phosphate (Curavis 250, Innophos, Cranbury, N.J., U.S.A.) and 0.3% salt on a finished weight basis. Enhancement solution, ph 7.2, was injected S6 JOURNAL OF FOOD SCIENCE Vol. 73, Nr. 1, 2008 C 2007 Institute of Food Technologists doi: /j x Further reproduction without permission is prohibited

2 changes in beef... (0 C, 1.5 Barr, 52 strokes/min, injection needles 2.5 cm apart) using a multi-injector system (Model N50, Wolf-tec Inc., Kingston, N.Y., U.S.A.). Muscles were weighed before and after enhancement to determine solution uptake. Each muscle (both enhanced and control) was divided into 2 sections (1 section/muscle/aging period), individually vacuum-packaged (Multivac C500, Koch Supplies Inc., Kansas City, Mo., U.S.A.), then aged at 4 Cfor7or14d.Sections were removed from vacuum bags, weighed for purge loss determination, sliced into 2.5-cm steaks, vacuum-packaged, and held at 4 C until evaluation (24 to 48 h). Color evaluation Following each aging period, sections were removed from vacuum packages and exposed surfaces were removed. Remaining section was allowed to bloom (30 min). After instrumental and visual color was evaluated, sections were cut into steaks. Instrumental color was determined using a reflectance spectrocolorimeter (Minolta Camera Co., Osaka, Japan) standardized using the white tile. Spectral curve was determined over the 400 to 700 nm range. CIE L (lightness), a (redness), and b (yellowness) values, hue angle (Tan 1 b /a ), and chroma [ (a ) 2 + (b ) 2 ] were calculated using illuminant D65 and the 10 standard observer (CIE 1978). A 10-member sensory panel was trained over a 2-wk period to evaluate raw color (red, brown, green) prior to cooking on a 15-cm semistructured line scale with 3 reference standards (Table 1). Reference standards were selected during training based on evaluation of fresh beef. Green color was included because of the potential for myoglobin degradation into choleglobin during aging. The panelists visually evaluated the color of steaks under fluorescent lights (750 lux) against a white background. Purge, cooking losses, and composition Sections were weighed before and after aging. Purge loss was calculated as: (Initial [enhanced] weight Post storage weight) 100 Purgeloss(%)= (Initial enhanced weight) Table Instrumental color values of visual color standards. CIE color values Color standard Scale position a L value a value b value Red Red Red Brown Brown Brown Green Green Green a Scale: φ = none, 15 = intense. Steaks used for sensory evaluation were weighed before and after cooking and cook loss was calculated as: (Raw weight Cooked weight) 100 Cooking loss(%) = (Raw weight) The ph of steaks was determined using a PH-STAR TM probe (SFK Technologies, Cedar Rapids, Iowa, U.S.A.). Moisture and fat content were determined following each aging period. The samples were trimmed of fat and connective tissue, homogenized (KitchenAid food processor, St. Joseph, Mich., U.S.A.). Samples (10 g) were oven dried to a constant weight (110 C for 48 h). Moisture content was determined by weight difference. Fat content was determined by extraction with an azeotropic mixture of warm chloroform and methanol (4:1; Novakofski and others 1989). Flavor and tenderness evaluation The 10-member sensory panel consisted of graduate students and staff at the Univ. of Illinois experienced in meat product evaluation by virtue of having participated in a minimum of 3 beef sensory panels over the last year. The panel was trained over a 2- wk period to evaluate tenderness, juiciness, saltiness, beef flavor, and oily mouthfeel (Moskowitz 1988; Prestat and others 2002) using cooked beef samples. Reference standards, shown in Table 2, were selected during training. Sample attributes were evaluated on a semistructured 15-cm line scale where 0 = none and 15 = intense. Standards were provided during all testing sessions. Flavor evaluation was conducted under controlled (dim) light conditions with 1 panelist per table. Samples were presented within 2 min of cooking. The flavor panel evaluated 2 sets of 5 samples per session allowing 3 min between samples and 1 h between sets. Four sessions were conducted daily, 2 in the morning and 2 in the afternoon. Both enhanced and nonenhanced samples were evaluated in random order across each session. Steaks were cooked to 70 C on Farberware Open Hearth grills (Model 455N, Walter Kidde, Bronx, N.Y., U.S.A.), turned approximately halfway through the cooking period. Internal temperature was monitored using copper constantin fine-wire thermocouples (Model 5SC-TT-T-30-36, Omega Engineering Inc., Stamford, Conn., U.S.A.) connected to a 12-channel scanning thermocouple thermometer (Model , Cole-Parmer Instrument Co., Vernon Hills, Ill., U.S.A.). Cooked samples were trimmed of edges, cut into serving pieces ( cm), coded with 3-digit random numbers, and presented to the panelists on white paper plates with apple juice and distilled water (23 C) to cleanse the palate. Sensory data are reported in centimeters from the left end of the line scale. Warner Bratzler shear force determination An additional steak from each treatment was cooked as previously described and cooled to room temperature (23 C). Cores (n = 4/steak), 1.3 cm in diameter, were removed from each sample parallel to the muscle fibers. Cores were sheared using an Instron Table Standards for sensory characteristics. Characteristic Standard Scale value Saltiness 0.25% NaCl solution 8 Beef flavor 0.25% Natural Roast Beef Flavor (Innova, Griffiths Lab., Oak Brook, Ill., U.S.A.) % NaCl solution Livery flavor Fresh beef liver, cooked to 70 C on open hearth grills 13 Rancid flavor Melted butter, stored at 22 Cfor4wk 10 Oiliness Old Wisconsin Premium Bratwurst (Fully Cooked, 33% fat, Old WI Food Prod. Co. Inc., 10 Sheboygan, Wis., U.S.A.). Reheated to 65 C. Tenderness All-beef Ball Park Franks (Ball Park Brands, Southfield, Mich., U.S.A.). Reheated to 65 C. 13 Juiciness Bob Evans Ham steaks (water added, 96% fat free, Bob Evans Farms, Columbus, Ohio, U.S.A.) 8 Vol. 73, Nr. 1, 2008 JOURNAL OF FOOD SCIENCE S7

3 changes in beef... Universal Testing Machine (Model 1122, Instron Corp., Canton, Mass., U.S.A.) fitted with a Warner Bratzler shear attachment. A full-scale load of 98.1 N (10 kg) was used; chart drive and crosshead speeds were 200 mm/min. expected to bind additional water increasing juiciness and tenderness. Salt may have enhanced beef flavor and increased saltiness sufficiently to mask rancid and liver off-flavors. However, sensory scores for both of these off-flavors were very low (< 1.0). Statistical analyses Data were analyzed as a repeated measures (carcass), 5 (muscles) by 2 (enhancement treatments) by 2 (aging periods) factorial design using PROC MIXED (SAS 2002). The model included muscle, aging time, enhancement, and appropriate interactions. Carcass was treated as a repeated measure to reduce the impact of carcass-tocarcass variation and because all treatment combinations (muscle/enhancement/aging time) were contained within each carcass. The effects were considered significant at P < Least squares means were separated using probability of difference. For flavor and visual evaluations, means of the panelists scores were calculated for each carcass/muscle/enhancement/aging combination. Results and Discussion No significant (P < 0.05) 3-way (muscle by enhancement by aging time) interactions existed for any of the characteristics evaluated. Effects of enhancement When data were pooled over muscle and aging time, enhancement increased (P < 0.05) tenderness, juiciness, and beef flavor and decreased rancid off-flavor, liver off-flavor, hue angle, and visual red and brown colors (Table 3). It decreased purge and cook losses (about 1.5% and 10% compared to the control, respectively; Table 3). Baublits and others (2006) reported that enhancing triceps brachii with solutions containing phosphate and salt significantly decreased purge compared to its nonenhanced counterpart. Baublits and others (2005b) reported decreased cook losses for enhanced beef biceps femoris by about 30%. This may have been partially a ph effect as the control muscle ph was 5.7 while samples enhanced with a salt-phosphate solution had a ph of 5.9. Control and enhanced sample ph in the present study ranged from 5.8 to 6.0 but did not differ significantly. Enhancement decreased shear values by about 0.5 kg (20%; Table 3). The solution added salt and phosphate, which would be Effects of aging Aging, when averaged over enhancement and muscle, had no significant effect on tenderness, juiciness, saltiness, oily mouthfeel, visual red, brown, or green color, ph, purge, or cook loss (Table 4). Eilers and others (1996) reported that tenderness of strip loin steaks improved as the postmortem aging period increased with the greatest improvements achieved by 12 d. Beef aged 14 d had lower rancid and liver off-flavor scores compared to that aged 7 d; however, all scores were very low (< 1.0 on a 15-point scale). This contrasts to the results reported by Spanier and others (1997) who found that postmortem aging increases bitter and sour off-flavors. In the present study, beef aged 14 d had higher L values, b values, and hue angles than that aged 7 d, indicating that samples aged 14 d became lighter and more yellow, and the color diverged from the true red axis of the color scale. Increases in the L values during aging of beef have been reported by Wicklund and others (2005). The findings in the present study indicate that, while instrumental measures indicate that aging had negative effects on color and positive effects on tenderness, these effects were imperceptible to the sensory panel. Beef aged 14 d had lower Warner Bratzler shear values than that aged 7 d (Table 4). Purchas and others (1999) reported that a parabolic relationship existed between shear force and ultimate ph. This relationship was similar before and after aging; however, the highest reductions in shear force with aging occurred close to the peak of toughness (at ph 5.9). In the present study, the ph did not differ statistically on days 7 and 14 (Table 4). While there was a difference in shear values due to aging, no difference existed in sensory tenderness. However, as an indicator of tenderness, Shackleford and others (1995) have noted that the relationship between Warner Bratzler shear values and tenderness is only moderate. Prior to aging, beef flavor intensity was higher for the complexus, serratus ventralis, and vastus lateralis (7.4 to 7.6) than for the longissiumus dorsi (7.2; data not shown). Lower beef flavor scores for the longissiumus dorsi than for 9 other beef muscles have also been Table Enhancement effects on characteristics of beef. a Enhancement Control Enhancement SEM Tenderness b 7.10 d 9.84 c 0.37 Juiciness b 7.21 d 8.77 c 0.54 Beef flavor b 6.71 d 8.00 c 0.06 Rancid off-flavor b 0.44 c 0.27 d 0.02 Liver off-flavor b 0.80 c 0.50 d 0.04 Red, visual b 5.56 c 4.65 d 0.08 Brown, visual b 3.17 c 2.90 d 0.08 Physical characteristics b value Hue c d 0.24 ph 5.77 d 6.02 d 0.03 Shear 3.15 c 2.45 d 0.09 Purge loss (%) 3.40 c 1.96 d 0.34 Cook loss (%) Moisture (%) c c 0.21 Fat (%) 5.92 c 5.27 d 0.22 a Pooled over muscle and aging time. b Sensory scale: φ = none; 15 = intense. cd Means in a row with different superscripts differ (P < 0.05). Table Aging time effects on characteristics of beef. Aging time (d) 7 14 SEM Tenderness a Juiciness a Saltiness a Oiliness a Rancid off-flavor a 0.40 b 0.30 c 0.02 Liver off-flavor a 0.72 b 0.58 c 0.04 Red, visual a Brown, visual a Green, visual a Physical characteristic L value c b 0.24 b value 6.62 c 6.96 b 0.13 Hue c b 0.24 ph Purge loss (%) Cook loss (%) Shear 2.94 b 2.65 c 0.09 bc Means in a row with different superscripts differ (P < 0.05). S8 JOURNAL OF FOOD SCIENCE Vol. 73, Nr. 1, 2008

4 changes in beef... reported by Shackelford and others (1995). Aging for 14 d decreased the beef flavor of the vastus lateralis; however, it had no effect on other muscles, and the range of scores was narrow (6.8 to 7.6; data not shown in tabular form). Wicklund and others (2005) reported that aging increased beef tenderness which was enhanced prior to aging achieved maximum tenderness by 14 d, while that enhanced after aging experienced little change. On the other hand, Brewer and Novakofski (2006) reported tenderness improvement of nonenhanced beef after only 7 d of aging. Enhancement effects on characteristics of individual muscles Complexus (chuck). When data were averaged over aging period, enhancement increased the oily mouthfeel (by about 10% on the 15-point scale) and saltiness (about 40% on the 15-point scale) of the complexus (Table 5). Enhancement decreased the L value (3.3 units), hue angle (6 ), and chroma (2.2 units), indicating that the complexus became lighter and more true red; however, the red color was less intense. The hue angle was the lowest for this muscle indicating that it was the most true red. When averaged over aging time and enhancement, the complexus did not differ in tenderness from the other muscles evaluated (Table 6). This muscle was in the higher visual red and hue angle and lower b value groups compared with other muscles. Serratus ventralis (chuck). Enhancement increased the oily mouthfeel (9%) and saltiness (30%) and decreased the a value (3.5 units) and chroma (3.7 units) of the serratus ventralis (Table5).This indicated that enhancement made his muscle less intensely red, but the color was a more true red. This muscle had the highest fat content (Table 6). Vastus lateralis (round). Compared to the control samples, enhancement slightly increased the oily mouthfeel and dramatically increased the saltiness of the vastus lateralis (Table 5). It decreased the L value (3 units). When averaged over aging time and enhancement, the vastus lateralis was less tender than the longissimus dorsi, which may be because the former is from the round and the latter is from the loin (Table 6). This muscle was numerically more visually red than the vastus medialis (also from the round) even though the ph values did not differ. It was the only muscle in which beef flavor intensity decreased during aging (7.4 to 6.8; data not shown). Vastus medialis (round). Compared to the control samples, enhancement increased the oily mouthfeel (8% based on the 15- point sensory scale; Table 5) and saltiness (30%). It decreased the a value (about 2.5 units), hue angle (>2 ), and chroma (3.5 units) of the vastus medialis (Table 5). Enhancement effect on various muscles Enhancement increased tenderness, juiciness, and beef flavor intensity and decreased off-flavors, visual red and brown colors, shear value, cook loss, and fat content in general (Table 3). Enhancement increased oily mouthfeel of all muscles but Table Enhancement effects on characteristics of various beef muscles. Control Enhancement Enhanced Complexus Serratus Vastus Vastus Longiss Complexus Serratus Vastus Vastus Longiss SEM ventralis lateralis medialis -iumus dorsi ventralis lateralis medialis -imus dorsi s Oily mouthfeel 3.16 cd 3.68 c 1.97 e 2.44 de 1.87 e 4.65 b 5.03 b 2.77 d 3.72 c 2.65 d 0.14 Saltiness 2.82 e 3.17 e 2.84 e 2.88 e 2.74 e 8.79 b 7.90 c 7.04 d 8.12 bc 7.48 c 0.18 Physical characteristics L value bc bcd b bcd b d bc cd d cd 0.50 a value bc b cd bc ef cde def def ef f 0.39 Hue angle bc cde b bc e f de bcd e f 0.58 Chroma bc b cd bc ef ef cde de ef f 0.40 bcd Means in a row with different superscripts differ (P < 0.05). Table Characteristics of various beef muscles. Muscle Complexus Serratus ventralis Vastus lateralis Vastus medialis Longissimus dorsi SEM Juiciness a Tenderness a 9.00 bc 8.26 bc 6.80 c 8.69 bc 9.61 b 0.55 Rancid off-flavor a 0.40 bc 0.44 b 0.37 bc 0.26 c 0.29 c 0.04 Liver off-flavor a Red, visual a 5.15 b 5.02 bc 5.52 c 4.81 c 5.03 c 0.13 Physical characteristic ph 5.91 c 6.07 b 5.81 c 5.93 bc 5.74 c 0.04 Shear NA e NA 2.48 c 3.39 b 2.52 c 0.11 b value 6.30 d 7.46 b 7.28 bc 6.52 cd 6.40 d 0.20 Hue d bc b c bc 0.35 Purge (%) Cook loss (%) Moisture (%) bc d b NA cd 0.30 Fat (%) 5.98 c 8.50 b 3.46 d NA 4.44 d 0.31 bcd Means in a row with different superscripts differ (P < 0.05). e Insufficient quantity of sample to conduct shear force determination in addition to sensory evaluation. Vol. 73, Nr. 1, 2008 JOURNAL OF FOOD SCIENCE S9

5 changes in beef... dramatically increased that of the complexus (chuck), serratus ventralis (chuck), and vastus medialis (round; Table 5). It increased saltiness of the complexus (chuck) and vastus medialis (round) to a much greater degree than it did in the other muscles. Baublits and others (2006) reported that enhancement increased tenderness and juiciness and slightly decreased beef flavor of triceps brachii. Wicklund and others (2005) reported similar results in longissimus. Baublits and others (2005b) found no differences in beef flavor intensity of beef biceps femoris due to enhancement. Enhancement decreased the L value of the complexus (chuck), vastus lateralis (round), and longissiumus dorsi (loin; Table 5) and decreased the a value of the serratus ventralis (chuck) and vastus medialis (round). Wicklund and others (2005) also reported that enhancement decreased the L value,andthatthel values of both enhanced and nonenhanced steaks decreased with aging time. In general, enhancement decreased the hue angle by about 2 to 4. Enhancement decreased the chroma of the complexus (chuck), serratus ventralis (chuck), and vastus medialis (round), indicating that they were more true red but lighter and less intensely colored. Wicklund and others (2005) reported similar results. They also reported that enhanced beef had lower a values at all aging times than nonenhanced beef. However, these differences were not clearly apparent to the sensory panelists. Conclusions Enhancement increased the positive sensory attributes (tenderness, juiciness, beef flavor, saltiness) and decreased the negative attributes (off-flavors) but had greater effects on some than on others. The complexus (chuck), serratus ventralis (chuck), and vastus medialis (round) especially seemed to benefit. Enhancement generally decreased instrumentally measured color values (L, a, and b values, and chroma) to varying degrees for various muscles. Aging had very small effects on beef flavor. Aging had overall positive, if small, effects of flavor (decreasing rancid and liver offflavors) and shear values, and caused a reduction of visual brown color, lightening, and yellowing the color. The various muscles differed in their tenderness, color, moisture, and fat content to begin with, which may explain some of the varying responses. References Baublits RT, Pohlman F, Brown AH. 2005a. Effects of enhancement with varying phosphate types and concentrations, at two different pump rates on beef biceps femoris instrumental color characteristics. Meat Sci 71: Baublits RT, Pohlman F, Brown AH. 2005b. Effects of sodium chloride, phosphate type and concentrations and pump rate on beef biceps femoris quality and sensory characteristics. 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