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Interrelationships between descriptive texture profile sensory panel and descriptive attribute sensory panel evaluations of beef Longissimus and Semitendinosus muscles
Meat Science 54 (2000) 325±332
www.elsevier.com/locate/meatsci
Interrelationships between descriptive texture pro®le sensory panel and descriptive attribute sensory panel evaluations of beef Longissimus and Semitendinosus muscles $
M.M. Otremba a,1, M.E. Dikeman a,*, G.A. Milliken b, S.L. Stroda a, E. Chambers IV c, D. Chambers c a
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506-0201, USA b Department of Statistics, Kansas State University, Manhattan, KS 66506-0802, USA c Department of Foods and Nutrition, Kansas State University, Manhattan, KS 66506-1401, USA Received 3 February 1999; received in revised form 15 July 1999; accepted 19 July 1999
Abstract The objectives of our study were to examine the relationships between highly trained and experienced descriptive texture pro®le (DTP) sensory panel and trained descriptive attribute (DA) sensory panel evaluations, and to evaluate the eects of muscle ®ber orientation on sensory panel tenderness scores of beef longissimus lumborum (LL) and semitendinosus (ST) muscles. Eighteen LL and 18 ST muscles were cut into 2.54 cm steaks and cooked to 71 C; then 1.271.272.54-cm cubes were removed using two methods (parallel with the muscle ®ber orientation and perpendicular to the steak cut surface) and presented to the two sensory panels. Both panels detected dierences among replications (muscles from dierent carcasses); however, a panelist replication eect occurred for the DA sensory panel. Both panels detected dierences (p<0.05) in LL muscle ®ber orientation for most attributes related to tenderness; however, few dierences were detected for ¯avor and juiciness traits for either muscle. Numerous signi®cant (r 5 0.50 or 4 ÿ0.50) correlations occurred between DTP and DA panel attributes and were generally higher when cubes were cut perpendicular to the steak cut surface. The DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle ®ber orientation. Both panels were eective in detecting dierences among replications. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Beef; Sensory panel; Texture pro®le
1. Introduction The American Meat Science Association's (1995) ``Research Guidelines: Cookery, Sensory Evaluation, and Instrumental Tenderness Measurement of Fresh Meat'' recommend that cores for Warner-Bratzler shear force determinations be taken parallel with the muscle ®ber orientation instead of perpendicular to the steak cut surface as previously recommended (American Meat $ Contribution no. 99-45-J from the Kansas Agric. Exp. Sta., Manhattan. * Corresponding author. Tel.: +1-785-532-1225; fax:+1-785-5327059. E-mail address: [email protected] (M.E. Dikeman). 1 Present adddress: Department of Animal Science, Oklahoma State University, Stillwater, OK 74074, USA.
Science Assocation, 1978). However, the recommendation of the American Meat Science Association (1995) for meat sample orientation for trained sensory panel evaluation has not changed; samples should be cut into cubes perpendicular to the steak surface, without mention of muscle ®ber orientation. The question of what type of panel is appropriate for speci®c research often arises. Numerous types of panels can be used, but the two most common are: (1) semitrained and (2) highly trained, experienced panels (Chambers, Bowers & Dayton, 1981; Chambers & Smith, 1993). Training increases their sensitivity, ensures uniform understanding of sensory properties and techniques, and minimizes eects of irrelevant factors (Dawson, Brogdon & Mcmanus, 1951; Zook & Wessman, 1977). The ability of various types of panels to perform sensory tests has not been widely studied. However, several
0309-1740/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(99)00099-6
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authors (Chambers et al., 1981; Chambers & Smith, 1993; Lawless, 1984) found that training increased panelists' abilities to measure dierences in products and that experience was important with lower levels of training and less important for higher levels of training. Training was more important for more dicult characteristics such as ¯avor of poultry (Chambers et al.) or wine (Lawless), but was not as important for dierentiating textural properties. Whether a semitrained or highly trained panel will give the same information or result in the same interpretation of meat palatability data is a question that has not been answered adequately. Therefore, the objectives of our study were to examine the relationships between highly trained, descriptive texture pro®le (DTP) sensory panel and trained, descriptive attribute (DA) sensory panel, and to evaluate the eects of muscle ®ber orientation of samples on sensory panel tenderness scores of beef longissimus and semitendinosus muscles. 2. Materials and methods 2.1. Preparation of meat The 180A beef short loins (NAMP, 1992) and 171C beef eye of rounds (NAMP) were obtained from 12 Choice and six Select carcasses (replications) from a commercial processor. This quality grade mix was selected because it often represents the target mix for the industry. At 3±5 days postmortem, subprimal cuts were frozen (ÿ40 C) and then cut into 14, 2.54-cm thick steaks, with subprimal identi®cations maintained throughout fabrication. Each steak was vacuum packaged. Steaks were numbered randomly and an SAS PROC plan (SAS, 1994) was used to assign steaks from each subprimal for both the longissimus lumborum (LL) and semitendinosus (ST) muscles randomly to treatments. Steaks were kept frozen (ÿ40 C) until evaluation. Steaks were thawed, with vacuum seals broken, at 0 C for 48 h prior to cooking on their preassigned evaluation dates. All steaks were cooked in a Blodgett modi®ed broiling oven (model # DFG-201, G.S. Blodgett Co., Inc., Burlington, VA) at 163 C; they were turned when internal temperature reached 35 C and cooked to an internal endpoint temperature of 71 C. Temperatures were monitored by 30 gauge, type-T thermocouples attached to a Doric temperature recorder (Model 205,Vas Engineering, San Francisco, CA). Steaks from each subprimal for both the LL and ST muscles were designated randomly to one of the following treatment groups: for the DTP sensory panel, three steaks were cut into 1.271.272.54-cm cubes with the long axis parallel with the muscle ®ber orientation, and three steaks were cut into 1.271.272.54-cm cubes
with the long axis perpendicular to the steak surface; for the DA sensory panel, two steaks were cut into 1.271.272.54-cm cubes with the long axis parallel to the muscle ®ber orientation and two steaks were cut into 1.271.272.54-cm cubes with the long axis perpendicular to the steak surface. All cubes were kept warm using double boiler pans with heated water in the bottom and served to panelists at 45±55 C. 2.2. Descriptive texture pro®le sensory panel The DTP sensory panel evaluations were conducted on the 18 replications of each muscle over a 3 week period using a six member, highly trained, experienced DTP sensory panel from The Sensory Analysis Center at Kansas State University. No more than eight samples representing two replications of the four treatment combinations of one muscle were presented in one test session in order to minimize panelist fatigue. Each sample was represented by 2±5 cubes. Each panelist had over 120 h of training by professional sensory analysts in the evaluation of ¯avor and texture characteristics, over 2000 h of sensory testing experience, and extensive experience in testing meat products. Panelists were orientated in four 1-h sessions prior to the beginning of the study. The DTP panel followed procedures outlined by the American Society of Testing Materials (ASTM, 1968) and Hootman (1992). Descriptive testing was performed in an environmentally controlled (211 C, 555% RH) booth-partitioned room with a mixture of adjustable red light (<107.64 lumens) and green light (<107.64 lumens). Three texture attributes were assessed: ®rmness, ®brousness, and chewiness. In addition, beef identi®cation, moistness, and juiciness were assessed (Table 1). One orientation (``warm up'') sample was evaluated and discussed orally prior to the beginning of each testing session. All attributes, descriptions, and references were generated by the DTP panelists, who had access to reference materials during each test session (Table 1). Unsalted crackers and deionized rinse water were used between individual samples that were presented about 5 min apart. Attributes of the samples were evaluated using a structured 15-pt scale (0=none to 15=very intense) with 0.5 intervals (Table 1). Panelists were instructed to place each parallel and perpendicular sample horizontally on their molars for evaluation. Each treatment was given a 3-digit numerical code, and order of presentation was randomized for every test session and for panelists within test session. 2.3. Descriptive attribute sensory panel Sensory tenderness evaluations were conducted for all replications of each muscle over a 7-week period using a 8±10-member, trained, DA panel. Panelists were
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Table 1 Descriptive sensory texture pro®le panel attribute de®nitions Juiciness
The amount of liquid expressed from the sample during the ®rst and second chews Reference: Fresh Tokay (red) seedless grapes=12; Beef Brisket=10 Grapes were sliced in half lengthwise and evaluated with skin side down to bottom molars. Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Moistness of mass
The amount of liquid observed in the mass after 7 chews with the molar teeth. (midpoint juicy) Reference: Chicken Breast=5; Beef Brisket=9.0 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish. It was allowed to cool and then cut into 1.27 cm cubes and served warm Prep: Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Firmness
The amount of force required to bite through the sample with the molar teeth. Measured by placing the sample between the molars and biting through during the 1st and 2nd chew until molars meet Reference: Wonder English Mun=5; Lender's Bagel (top)=12, Beef Brisket=14.5 Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Fibrousness Filaments or strands of muscle tissue Reference: Chicken Breast=10 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish, allowed to cool, then cut into 1.27 1.27 cm cubes, and served warm Chewiness
The number of chews necessary to reduce the sample to a consistency ready for swallowing Reference: Chicken Breast=10 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish, allowed to cool, cut into 1.271.27 cm cubes, and served warm
Beef ID (¯avor)
The intensity with which the sample is recognized as distinctly beef lean muscle tissue rather than another type of protein product Reference: Beef Brisket=13.5 Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
screened, trained, and evaluated prior to the initiation of the study according to AMSA (1995) guidelines. This procedure required several weeks. The same procedures for thawing and cooking were used as for the DTP panel. Descriptive testing was performed in the same environmentally controlled (211 C, 555% RH), booth-partitioned room as described for the DTP panel. One orientation (``warm up'') sample was evaluated and discussed orally prior to the beginning of each testing session. No more than eight samples representing two replications of the four treatment combinations of one muscle were presented in one test session in order to minimize panelist fatigue. Each sample was represented by two cubes. Five attributes were assessed: myo®brillar tenderness, connective tissue amount, juiciness, beef ¯avor intensity, and overall tenderness (Table 2). The same procedures for cube removal were used as for the DTP panel. Unsalted crackers and deionized rinse water were used between individual samples that were presented about 2 min apart. Samples were evaluated for the ®ve attributes using an 8-point number scale and scored to the nearest .5 (Table 2). Order of presentation was randomized for every test session. Panelists were instructed to place each parallel and perpendicular cube horizontally on their molars for evaluation. 2.4. Statistical analyses The statistical design was a type of split plot design. Statistical analysis of DA and DTP panel data was performed by using PROC MIXED procedure of SAS1
(1994). The analysis of variance model for individual panel attributes consisted of the main eects and interaction for muscle type and cube plus error terms for panelists, cubes within a muscle type, steaks within a muscle, and sensory cubes within a steak. Pearson correlation coecients were calculated among the DA and DTP panel data by using the SAS1 system 3. Results and discussion The DTP panel detected dierences (p<0.05) among replications (muscles from dierent carcasses) for each muscle (LL and ST) for each of the six attributes evaluated (chewiness, beef identi®cation, ®brousness, ®rmness, moistness, and juiciness) (Table 3). No dierences (p>0.05) occurred among DTP panelists for any of the six attributes (no panelist eect), and there was no (p>0.05) panelist by replication eect. These results suggest that the panelists could detect dierences consistently. The DA panel also detected dierences (p<0.05) among replications for each muscle (LL and ST) for each of the ®ve attributes evaluated (juiciness, myo®brillar tenderness, connective tissue amount, overall tenderness, and beef ¯avor intensity) (Table 4). However, a panelist eect (p<0.05) occurred for each of the ®ve attributes. In addition, a panelist by replication eect (p<0.05) occurred, suggesting that panelists were not consistent in their evaluations. The longer time interval for the DA panel evaluations (7 week) than for the DTP panel evaluations (3 weeks) could partially
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Table 2 Descriptive attribute sensory panel 8-pt number scale de®ned Attributes Myo®brillar tendernessa
Juicinessb
Beef ¯avor intensityc
Connective tissue amountd
Overall tendernesse
1. Extremely tough 2. Very tough 3. Moderately tough 4. Slightly tough 5. Slightly tender 6. Moderately tender 7. Very tender 8. Extremely tender
1. Extremely dry 2. Very dry 3. Moderately dry 4. Slightly dry 5. Slightly juicy 6. Moderately juicy 7. Very juicy 8. Extremely juicy
1. Extremely bland 2. Very bland 3. Moderately bland 4. Slightly bland 5. Slightly intense 6. Moderately intense 7. Very intense 8. Extremely intense
1. Abundant 2. Moderately abundant 3. Slightly abundant 4. Moderate 5. Slight 6. Traces 7. Practically none 8. None
1. Extremely tough 2. Very tough 3. Moderately tough 4. Slightly tough 5. Slightly tender 6. Moderately tender 7. Very tender 8. Extremely tender
a b c d e
The perception of how tough or tender the myo®brillar component of that sample is. The amount of liquid expressed from the sample during the initial chews. The intensity with which the beef sample is recognized as distinctly beef lean tissue rather than another species of meat. The amount of connective tissue remaining in the palate upon completion of mastication, prior to swallowing. The perception of how tough or tender a meat sample is at the completion of mastication.
Table 3 Descriptive texture pro®le (DTP) sensory panel and descriptive attribute (DA) sensory panel analysis of variance for replication, panelist, and panelistreplication eects Attribute
Replication Panelist Panelist X (muscle) eect eect replication eect
DTP sensory panel Chewiness Beef identi®cation Fibrousness Firmness Moistness Juiciness
Ya Y Y Y Y Y
Nb N N N N N
N N N N N N
DA sensory panel Juiciness Myo®brillar tenderness Connective tissue amount Overall tenderness Beef ¯avour intensity
Y Y Y Y Y
Y Y Y Y Y
Y Y Y Y Y
a b
Y=signi®cant eect (p<0.05). N=no signi®cant eect (p>0.05).
explain the lower consistency. Although descriptive analysis methods have been in use for decades, researchers have sought ways to obtain detailed descriptions with less training and practice for panelists (Civille, 1994). Oreskovich (1994) compared results from a conventionally trained descriptive panel to results from a free-choice, pro®ling panel for a ¯avor and texture analysis of pork. She concluded that the free-choice panel could discriminate and describe dierences in pork treatment eects but the free-choice method did not describe attributes that characterize the unique properties of food. These results further support those from a study conducted by Chambers and Smith (1993), who found that training may be more important than experience for increased ``reproducibility'' in panelists. Each of our panels was experienced in sensory testing of
meat; however, the DTP panel was more highly trained than the DA panel, resulting in greater consistency. The dierences in scales should not have been a factor because Lawless and Malone (1986) used various scales with trained panelists and found no eect of the dierent scales. In addition, Chambers and Wolf (1996) stated that dierences in scales with trained panels did not signi®cantly aect responses. The DTP panel detected dierences (p<0.05) between cubes taken parallel with the muscle ®ber orientation and cubes taken perpendicular to the steak cut surface in the LL muscle for the attributes of chewiness, beef identi®cation, ®brousness, and ®rmness (Table 4) because muscle ®ber orientation was quite dierent. However, neither muscle ®ber orientation resulted in consistently higher or lower values. The attributes of moistness and juiciness for which the panel did not detect dierences (p>0.05, Table 4) probably do not have any relationship with muscle ®ber orientation. For the ST muscle, a dierence was detected between muscle ®ber orientation only for beef identi®cation. We have no logical explanation for this observation because the orientation of muscle ®bers essentially was the same for parallel and perpendicular cubes. The fact that the DTP panel was sensitive (p<0.05) to muscle ®ber orientation for attributes related to LL tenderness implies that samples taken parallel with the muscle ®ber orientation or perpendicular to the cut steak surface might make a dierence in the interpretation of results. The DA panel scored cubes lower (6.1 vs 6.3 and 6.3 vs 6.5, respectively; p<0.05) for the attributes of myo®brillar tenderness and overall tenderness (less tender) when they were taken parallel to the muscle ®ber orientation than when they were taken perpendicular to the steak cut surface in the LL muscle (Table 4). The attributes of juiciness and beef ¯avor intensity for which the DA panel did not detect any dierences (p>0.05, Table 4) probably are not dependent upon muscle ®ber orientation. For the
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Table 4 Descriptive texture pro®le (DTP) and descriptive attribute (DA) sensory panel interactions between parallel and perpendicular samples for each attribute within each muscle (Longissimus and Semitendinosus) Treatments Longissimus
Semitendinosus
Attribute
Parallel
Perpendicular
Parallel
Perpendicular
DTP sensory panela Chewiness Beef identi®cation Fibrous Firmness Moistness Juiciness
7.9c 10.9c 9.3c 7.6c 8.3c 8.8c
7.6d 10.6d 8.9d 7.3d 8.4c 8.7c
8.3c 9.8c 9.5c 8.4c 7.0c 7.1c
8.4c 9.4d 9.5c 8.4c 7.1c 7.2c
DA sensory panelb Juiciness Myo®brillar tenderness Connective tissue amount Overall tenderness Beef ¯avour intensity
5.5c 6.1c 6.6c 6.3c 5.7c
5.5c 6.3d 6.7c 6.5d 5.6c
4.9c 5.6c 5.4c 5.4c 5.2c
5.1d 5.8d 5.5c 5.6d 5.2c
a
DTP scale, 0=none to 15=very intense. DA scale, 1=extremely dry, extremely tough, abundabunt, extremely tough, and extremely bland; 8=extremely juicy, extremely tender, none, extremely tender, extremely intense. c Means in the same row within a muscle lacking a common superscript letter dier (p<0.05). d Means in the same row within a muscle lacking a common superscript letter dier (p<0.05). b
ST muscle, the DA panel scored perpendicular cubes higher (p<0.05) for juiciness, myo®brillar tenderness, and overall tenderness, but the magnitude of these differences was small and may not be of practical importance because orientation essentially is the same for both cubing methods. 3.1. Correlations between DTP panel attributes and DA sensory panel attributes Correlation coecients were calculated between attributes evaluated by the DTP panel and attributes evaluated by the DA panel for each treatment combination (LL parallel cubes, LL perpendicular cubes, ST parallel cubes, and ST perpendicular cubes) (Table 5). For LL samples that were taken parallel with the muscle ®ber orientation, the DTP and DA panel attributes that were correlated (p<0.05) were moistness with juiciness (r=0.51), moistness with myo®brillar tenderness (r=0.51), moistness with overall tenderness (r=0.51), ®rmness with myo®brillar tenderness (r=ÿ0.61), ®rmness with connective tissue amount (r=ÿ0.76), and ®rmness with overall tenderness (r=ÿ0.62). For LL cubes that were taken perpendicular to the steak cut surface, the DTP panel attributes and the DA panel attributes that were correlated (p<0.05) were: juiciness with juiciness (r=0.54), juiciness with myo®brillar tenderness (r=0.55), juiciness with overall tenderness (r=0.53), moistness with juiciness (r=0.55), moistness with myo®brillar tenderness (r=0.52), moistness with overall tenderness (r=0.50), ®rmness with
juiciness (r=ÿ0.68), ®rmness with myo®brillar tenderness (r=ÿ0.73), ®rmness with connective tissue amount (r=ÿ0.67), ®rmness with overall tenderness (r=ÿ0.69), chewiness with juiciness (r=ÿ0.67), chewiness with myo®brillar tenderness (r=ÿ0.68), chewiness with connective tissue amount (r=ÿ0.60), and chewiness with overall tenderness (r=ÿ0.69) (Table 5). These correlations show that the DTP panel trait of ®rmness was highly related to the DA panel tenderness traits and that moistness and juiciness were positively related to tenderness traits, regardless of muscle ®ber orientation. However, these results show that a greater number of traits were correlated more highly (r50.50 and r4ÿ0.50) when cubes were removed perpendicular to the steak cut surface than when removed parallel with the muscle ®ber orientation. Otremba, Dikeman, Hilliken, Stroda, Unruh and Chambers (1999) reported that correlations between DTP and DA panel evaluations and Warner-Bratzler shear force for the LL muscle were higher when cores were removed perpendicular to the steak cut surface than when removed parallel to the muscle ®ber orientation. These results contradict those of Poste, Butler, Mackie, Agar and Thompson, (1993) that parallel cores were slightly better than perpendicular cores for detecting treatment dierences and achieving high correlation values between WarnerBratzler shear values and sensory panel evaluations. For ST samples that were taken parallel to the muscle ®ber orientation, the DTP and DA panel attributes that were correlated (p<0.05) were: ®rmness with myo®brillar tenderness (r=ÿ0.69), ®rmness with connective
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Table 5 Correlations between descriptive texture pro®le (DTP) sensory panel attributes and descriptive attribute (DA) panel attributes for each treatment combination (Longissimus parallel, Longissimus perpendicular, Semitendinosus parallel, and Semitendinosus perpendicular)a Treatments DTP attribute vs DA attribute
Longissimus parrallel r
Longissimus perpendicular r
Semitendinosus parallel r
Semitendinosus perpendicular r
Juiciness/juiciness Juiciness/myo®brillar tenderness Juiciness/connective tissue amount Juiciness/overall tenderness Juiciness/beef ¯avor intensity Moistness/juiciness Moistness/myo®brillar tenderness Moistness/connective tissue amount Moistness/overall tenderness Moistness/beef ¯avor intensity Firmness/juiciness Firmness/myo®brillar tenderness Firmness/connective tissue amount Firmness/overall tenderness Firmness/beef ¯avor intensity Fibrousness/juiciness Fibrousness/myo®brillar tenderness Fibrousness/connective tissue amount Fibrousness/overall tenderness Fibrousness/beef ¯avor intensity Chewiness/juiciness Chewiness/myo®brillar tenderness Chewiness/connective tissue amount Chewiness/overall tenderness Chewiness/beef ¯avor intensity Beef identi®cation/juiciness Beef identi®cation/myo®brillar tenderness Beef identi®cation/connective tissue amount Beef identi®cation/overall tenderness Beef identi®cation/beef ¯avor intensity
0.39 0.49 0.48 0.49 0.19 0.51 0.51 0.49 0.51 0.15 ÿ0.45 ÿ0.61 ÿ0.76 ÿ0.62 ÿ0.24 ÿ0.30 ÿ0.42 ÿ0.32 ÿ0.39 0.01 ÿ0.19 ÿ0.11 ÿ0.24 ÿ0.09 0.28 0.38 0.19 0.25 0.33 0.30
0.54 0.55 0.36 0.53 0.49 0.55 0.52 0.33 0.50 0.44 ÿ0.68 ÿ0.73 ÿ0.67 ÿ0.69 ÿ0.39 ÿ0.11 ÿ0.19 ÿ0.17 ÿ0.24 ÿ0.24 ÿ0.67 ÿ0.68 ÿ0.60 ÿ0.69 ÿ0.47 0.35 0.25 0.34 0.29 0.38
ÿ0.06 ÿ0.19 ÿ0.38 ÿ0.24 ÿ0.01 ÿ0.03 ÿ0.14 ÿ0.38 ÿ0.21 ÿ0.01 ÿ0.33 ÿ0.69 ÿ0.58 ÿ0.65 ÿ0.38 ÿ0.43 ÿ0.47 ÿ0.35 ÿ0.39 ÿ0.38 ÿ0.27 ÿ0.49 ÿ0.28 ÿ0.40 ÿ0.31 0.27 0.28 ÿ0.10 ÿ0.04 ÿ0.03
0.27 0.18 ÿ0.34 ÿ0.47 0.24 0.29 0.22 ÿ0.29 0.01 0.30 ÿ0.33 ÿ0.65 ÿ0.54 ÿ0.66 ÿ0.63 ÿ0.50 ÿ0.59 ÿ0.33 ÿ0.50 ÿ0.42 ÿ0.40 ÿ0.61 ÿ0.12 ÿ0.46 ÿ0.65 ÿ0.07 ÿ0.22 ÿ0.50 ÿ0.50 ÿ0.52
a
Correlations 5 0.50 r 4 ÿ0.05 are signi®cant (p<0.05).
tissue amount (r=ÿ0.58), and ®rmness with overall tenderness (r=ÿ0.65) (Table 5). For ST samples that were taken perpendicular to the steak cut surface, the DTP panel attributes and the DA panel attributes that were correlated (p<0.05) were: ®rmness with myo®brillar tenderness (r=ÿ0.65), ®rmness with connective tissue amount (r=ÿ0.54), ®rmness with overall tenderness (r=ÿ0.66), ®brousness with myo®brillar tenderness (r=ÿ0.59), ®brousness with overall tenderness (r=ÿ0.66), chewiness with myo®brillar tenderness (r=ÿ0.61) (Table 5). These correlations show that the DTP panel trait of ®rmness was highly related to the DA panel tenderness traits regardless of muscle ®ber orientation. Again, a greater number of traits were correlated more highly (r>0.50) when cubes were removed perpendicular to the steak cut surface than when removed parallel with the muscle ®ber orientation. Otremba et al. (1999) reported that correlations between DTP and DA panel evaluations and Warner-Bratzler shear force for the LL muscle were
higher when cores were removed perpendicular to the steak cut surface than when removed parallel to the muscle ®ber orientation. Our results and those of Otremba et al. suggest that removing cubes perpendicular to the steak cut surface may be the preferred method for sensory panel evaluation. The fact that the DTP panel attributes of juiciness and moistness were signi®cantly correlated to the DA panel attributes of myo®brillar tenderness and overall tenderness implies that as the DTP panel's perception of juiciness increased, the DA panel's perception of tenderness increased, indicating that juiciness and tenderness are positively related. The DTP panel attributes of juiciness and moistness also were correlated (p<0.05) to the DA panel attribute of juiciness in the LL muscle. This implies that the DTP attributes of juiciness and moistness and the DA attribute of juiciness are measuring a similar attribute. Negative correlations (p<0.05) occurred between the attributes of ®rmness with myo®brillar tenderness,
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®rmness with connective tissue amount, and ®rmness with overall tenderness for all treatment combinations (LL parallel, LL perpendicular, ST parallel, and ST perpendicular) (Table 5). This ®nding indicates that the DTP panel's attribute of ®rmness is most likely measuring the same sample qualities that are being measured in the DA panel attributes of myo®brillar tenderness, connective tissue amount, and overall tenderness. The negative correlations occurred because on the DTP panel's 15-point scale, an increase in ®rmness score means a decrease in tenderness (sample is getting tougher), whereas on the DA panel's 8-point scale, an increase in score implies an increase in tenderness. Even though the DTP panel attribute of ®brousness was correlated signi®cantly to the DA panel attributes for the ST perpendicular samples, low correlations were found over the remaining treatment combinations, indicating that the DTP attribute of ®brousness is not related very well to DA panel attributes (Table 5). The DTP panel attribute of chewiness was correlated (P<0.05) with some of the DA panel's attributes related to tenderness, but mainly in LL samples, implying that DTP chewiness is similar to DA attributes associated with tenderness. The DTP attribute of beef identi®cation was correlated signi®cantly to some DA tenderness-related attributes in ST perpendicular samples only, implying that as tenderness was perceived to be greater by the DA panel, ¯avor was perceived to be higher by the DTP panel (Table 5). This could be what is sometimes referred to as the ``halo'' eect described by Howard (1972) and Chambers and Wolf (1996), meaning that as the perception of one trait increases the perception of one or more other traits increases without a cause and eect. However, for our ST parallel, LL parallel, and LL per-
331
pendicular samples, not many signi®cant correlations occurred among the DTP attribute of beef identi®cation and the DA panel attributes, implying that the DTP panel attribute of beef identi®cation (which measures ¯avor) is unrelated to most of the DA panel attributes, even beef ¯avor intensity. One would assume that the ¯avor assessment by each panel would be related highly. Chambers et al. (1981) reported that for such complex sensory characteristics as ¯avor, highly trained and experienced panelists may have less random error than panelists with less experience or training. Because panelist eect or panelistreplication eect did not occur for the DTP panel but did for the DA panel, low correlations between beef identi®cation and beef ¯avor intensity might be expected. Or, the limited variability in ¯avor in our samples may have resulted in low correlations. On the other hand, the same panel and panelistreplication eects existed for DA panel attributes related to tenderness, but correlations with the DTP attribute of ®rmness were consistently high. Chambers et al. (1981) conducted a study comparing a highly trained, experienced panel of three people with a seven- or eight-member panel of semi-trained individuals. They found that the highly trained, experienced panel had lower residual error mean squares than did the semi-trained panel. We also found that our DTP panel had lower residual error mean squares than the DA panel. Chambers et al. also reported that the semitrained panel found signi®cant dierences in more characteristics than did the highly trained, experienced panel, but the highly trained, experienced panel found more main eect and interaction dierences in characteristics for which both panels detected signi®cant dierences. Both panels in our study were able to detect dierences among replications (Tables 3 and 4).
Table 6 Correlations among descriptive texture pro®le (DTP) sensory panel attributes and among descriptive attribute (DA) sensory panel attributes for pooled parallel and perpendicular cores and longissimus and semitendinosus musclesa DTP sensory panel attributes
r
Juiciness/moistness Juiciness/®rmness Juiciness/®brousness Juiciness/chewiness Juiciness/beef identi®cation Moistness/®rmness Moistness/®brousness Moistness/chewiness Moistness/beef identi®cation Firmness/®brousness Firmness/chewiness Firmness/beef identi®cation Fibrous/chewiness Fibrous/beef identi®cation Chewiness/beef identi®cation
0.98 ÿ0.58 ÿ0.50 ÿ0.65 0.70 ÿ0.57 ÿ0.53 ÿ0.66 0.69 0.55 0.76 ÿ0.33 0.69 ÿ0.32 ÿ0.48
a
Correlations 5 0.50 r 4 ÿ0.05 are signi®cant (p<0.05).
DA sensory panel attributes
r
Juiciness/myo®brilliar tenderness Juiciness/connective tissue amount Juiciness/overall tenderness Juiciness/beef ¯avor intensity Myo®brillar/connective tissue Myo®brillar/overall tenderness Myo®brillar/beef ¯avor intensity Connective tissue amount/overall tenderness Connective tissue amount/beef ¯avor intensity Overall tenderness/beef ¯avor intensity
0.69 0.55 0.69 0.54 0.72 0.93 0.58 0.91 0.56 0.64
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3.2. Correlations among attributes within each panel
References
Correlation coecients also were calculated among attributes evaluated within each panel (Table 6). For the DTP panel, signi®cant correlations existed for almost every attribute with another, except for ®rmness with beef identi®cation (r=ÿ0.33) and ®brousness with beef identi®cation (r=ÿ0.32). This may have been due to the fact that these attributes are measuring unrelated qualities of beef. Some attributes that were correlated more highly (r>0.70) were juiciness with moistness (r=0.98) and ®rmness with chewiness (r=0.76), probably because these attributes are measuring similar qualities of beef. For example, juiciness and moistness may be perceived as a similar characteristic by the panelists, hence resulting in such a high correlation. These high correlations raise the question of why two attributes that are so similar to each other are evaluated, when evaluating either one individually might give the same information. Correlation coecients also were calculated among attributes evaluated within the DA panel (Table 6). Correlations (p<0.05) greater than or equal to .54 were found among all attributes. Attributes that were correlated more highly (r>0.70) were found for myo®brillar tenderness with connective tissue amount (r=0.72), myo®brillar tenderness with overall tenderness (r=0.93), and connective tissue amount with overall tenderness (r=0.91). These attributes may be measuring similar characteristics, and(or) as the perception of one attribute increases or decreases, the perception of the other also increases or decreases.
American Meat Science Association (1978). Guidelines for cookery and sensory evaluation of meat. American Meat Science Association in cooperation with the National Livestock and Meat Board (now the National Cattlemen's Beef Association), Engelwood, CO. American Meat Science Association (1995). Research guidelines: for cookery, sensory evaluation and instrumental tenderness measurements of fresh meat. Published by AMSA in cooperation with the National Livestock and Meat Board. American Society for Testing and Materials. (1968). American Society for testing and materials manual on sensory testing methods. Philadelphia, PA: ASTM. Chambers IV, E., & Wolf, M. B. (1996). Sensory testing methods (2nd Ed.). West Conshocken, PA: ASTM. Chambers IV, E., Bowers, J. A., & Dayton, A.D. (1981). Statistical designs and panel training/experience for sensory analysis. J. Food Sci., 46, 1902. Chambers IV, E., & Smith, E. A. (1993). Eects of testing experience on performance of trained sensory panelists. J. Sensory Stud., 8, 155. Civille, G. V. (1994). New sensory methods and sensory attributes for new products. Proc. Reciprocal Meats Conf. American Meat Science Assoc. (Vol. 47 pp. 17±26). In Cooperation with the National Live Stock and Meat Board (now the National Cattlemen's Beef Association). Dawson, E. H., Brogdon, J. L., & McManus, S. (1951). Sensory testing of dierences in taste. II. Selection of panel members. Food Technol, 17(12), 39±43. Hootman, R. C. (1992). Manual on descriptive analysis testing for sensory evaluation. Philadelphia, PA: American Society for Testing and Materials. Howard, A. (1972). Taste panel techniques: 1. Reproducibility, reliability, and validity. CSIRO Food Research Quarterly, 32(6), 80±84. Lawless, H. T. (1984). Flavor description of white wine by ``expert'' and ``non expert'' wine consumers. J. Food Sci, 49, 120±123. Lawless, H. T., & Malone, G. J. (1986). A comparison of rating scales: Sensitivity, replicates, and relative judgements. J. Sensory Stud, 1, 155±174. NAMP (1992). The Meat Buyers Guide. Reston, VA: NAMP. Oreskovich, D. C. (1994). A comprehensive approach to determining the nutritional and sensory properties of today's cooked pork. Ph.D. thesis, University of Illinois at Urbana-Champaign. Otremba, M. M., Dikeman, M. E., Milliken, G. A., Stroda, S. L., Unruh, J. A., & Chambers IV, E. (1999). Interrelationships among evaluations of beef longissimus and semitendinosus muscle tenderness by Warner-Bratzler shear force, and descriptive-texture pro®le sensory panel, and a descriptive attribute sensory panel. J. Anim. Sci., 77, 865±873. Poste, L. M., Butler, G., Mackie, D., Agar, V. E., & Thompson, B. K. (1993). Correlations of sensory and instrumental meat tenderness values as aected by sampling technique. Food Qual. Pref, 4, 207± 214. SAS Institute Inc. (1994). SAS/STAT1 Software: changes and enhancements, Release 6.10. Cary, NC: SAS Institute Inc. Zook, K., & Wessman, C. (1977). The selection and use of judges for descriptive panels. Food Technol, 31(11), 56±61.
4. Implications Our results suggest that a highly trained descriptive texture pro®le sensory panel may be able to detect more subtle dierences among treatments because panelist variation may be less than in a trained descriptive attribute sensory panel trained according to the American Meat Science Association (1995) guidelines. Using cubes removed perpendicular to the steak cut surface might result in higher relationships among texture-related attributes between the two types of panels than using those removed parallel with muscle ®ber orientation. Flavor evaluation by either type of panel should not be expected to be related highly to other attributes or to the other panel. Both panels should be expected to be eective in detecting dierences among replications.
www.elsevier.com/locate/meatsci
Interrelationships between descriptive texture pro®le sensory panel and descriptive attribute sensory panel evaluations of beef Longissimus and Semitendinosus muscles $
M.M. Otremba a,1, M.E. Dikeman a,*, G.A. Milliken b, S.L. Stroda a, E. Chambers IV c, D. Chambers c a
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS 66506-0201, USA b Department of Statistics, Kansas State University, Manhattan, KS 66506-0802, USA c Department of Foods and Nutrition, Kansas State University, Manhattan, KS 66506-1401, USA Received 3 February 1999; received in revised form 15 July 1999; accepted 19 July 1999
Abstract The objectives of our study were to examine the relationships between highly trained and experienced descriptive texture pro®le (DTP) sensory panel and trained descriptive attribute (DA) sensory panel evaluations, and to evaluate the eects of muscle ®ber orientation on sensory panel tenderness scores of beef longissimus lumborum (LL) and semitendinosus (ST) muscles. Eighteen LL and 18 ST muscles were cut into 2.54 cm steaks and cooked to 71 C; then 1.271.272.54-cm cubes were removed using two methods (parallel with the muscle ®ber orientation and perpendicular to the steak cut surface) and presented to the two sensory panels. Both panels detected dierences among replications (muscles from dierent carcasses); however, a panelist replication eect occurred for the DA sensory panel. Both panels detected dierences (p<0.05) in LL muscle ®ber orientation for most attributes related to tenderness; however, few dierences were detected for ¯avor and juiciness traits for either muscle. Numerous signi®cant (r 5 0.50 or 4 ÿ0.50) correlations occurred between DTP and DA panel attributes and were generally higher when cubes were cut perpendicular to the steak cut surface. The DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle ®ber orientation. Both panels were eective in detecting dierences among replications. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Beef; Sensory panel; Texture pro®le
1. Introduction The American Meat Science Association's (1995) ``Research Guidelines: Cookery, Sensory Evaluation, and Instrumental Tenderness Measurement of Fresh Meat'' recommend that cores for Warner-Bratzler shear force determinations be taken parallel with the muscle ®ber orientation instead of perpendicular to the steak cut surface as previously recommended (American Meat $ Contribution no. 99-45-J from the Kansas Agric. Exp. Sta., Manhattan. * Corresponding author. Tel.: +1-785-532-1225; fax:+1-785-5327059. E-mail address: [email protected] (M.E. Dikeman). 1 Present adddress: Department of Animal Science, Oklahoma State University, Stillwater, OK 74074, USA.
Science Assocation, 1978). However, the recommendation of the American Meat Science Association (1995) for meat sample orientation for trained sensory panel evaluation has not changed; samples should be cut into cubes perpendicular to the steak surface, without mention of muscle ®ber orientation. The question of what type of panel is appropriate for speci®c research often arises. Numerous types of panels can be used, but the two most common are: (1) semitrained and (2) highly trained, experienced panels (Chambers, Bowers & Dayton, 1981; Chambers & Smith, 1993). Training increases their sensitivity, ensures uniform understanding of sensory properties and techniques, and minimizes eects of irrelevant factors (Dawson, Brogdon & Mcmanus, 1951; Zook & Wessman, 1977). The ability of various types of panels to perform sensory tests has not been widely studied. However, several
0309-1740/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0309-1740(99)00099-6
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authors (Chambers et al., 1981; Chambers & Smith, 1993; Lawless, 1984) found that training increased panelists' abilities to measure dierences in products and that experience was important with lower levels of training and less important for higher levels of training. Training was more important for more dicult characteristics such as ¯avor of poultry (Chambers et al.) or wine (Lawless), but was not as important for dierentiating textural properties. Whether a semitrained or highly trained panel will give the same information or result in the same interpretation of meat palatability data is a question that has not been answered adequately. Therefore, the objectives of our study were to examine the relationships between highly trained, descriptive texture pro®le (DTP) sensory panel and trained, descriptive attribute (DA) sensory panel, and to evaluate the eects of muscle ®ber orientation of samples on sensory panel tenderness scores of beef longissimus and semitendinosus muscles. 2. Materials and methods 2.1. Preparation of meat The 180A beef short loins (NAMP, 1992) and 171C beef eye of rounds (NAMP) were obtained from 12 Choice and six Select carcasses (replications) from a commercial processor. This quality grade mix was selected because it often represents the target mix for the industry. At 3±5 days postmortem, subprimal cuts were frozen (ÿ40 C) and then cut into 14, 2.54-cm thick steaks, with subprimal identi®cations maintained throughout fabrication. Each steak was vacuum packaged. Steaks were numbered randomly and an SAS PROC plan (SAS, 1994) was used to assign steaks from each subprimal for both the longissimus lumborum (LL) and semitendinosus (ST) muscles randomly to treatments. Steaks were kept frozen (ÿ40 C) until evaluation. Steaks were thawed, with vacuum seals broken, at 0 C for 48 h prior to cooking on their preassigned evaluation dates. All steaks were cooked in a Blodgett modi®ed broiling oven (model # DFG-201, G.S. Blodgett Co., Inc., Burlington, VA) at 163 C; they were turned when internal temperature reached 35 C and cooked to an internal endpoint temperature of 71 C. Temperatures were monitored by 30 gauge, type-T thermocouples attached to a Doric temperature recorder (Model 205,Vas Engineering, San Francisco, CA). Steaks from each subprimal for both the LL and ST muscles were designated randomly to one of the following treatment groups: for the DTP sensory panel, three steaks were cut into 1.271.272.54-cm cubes with the long axis parallel with the muscle ®ber orientation, and three steaks were cut into 1.271.272.54-cm cubes
with the long axis perpendicular to the steak surface; for the DA sensory panel, two steaks were cut into 1.271.272.54-cm cubes with the long axis parallel to the muscle ®ber orientation and two steaks were cut into 1.271.272.54-cm cubes with the long axis perpendicular to the steak surface. All cubes were kept warm using double boiler pans with heated water in the bottom and served to panelists at 45±55 C. 2.2. Descriptive texture pro®le sensory panel The DTP sensory panel evaluations were conducted on the 18 replications of each muscle over a 3 week period using a six member, highly trained, experienced DTP sensory panel from The Sensory Analysis Center at Kansas State University. No more than eight samples representing two replications of the four treatment combinations of one muscle were presented in one test session in order to minimize panelist fatigue. Each sample was represented by 2±5 cubes. Each panelist had over 120 h of training by professional sensory analysts in the evaluation of ¯avor and texture characteristics, over 2000 h of sensory testing experience, and extensive experience in testing meat products. Panelists were orientated in four 1-h sessions prior to the beginning of the study. The DTP panel followed procedures outlined by the American Society of Testing Materials (ASTM, 1968) and Hootman (1992). Descriptive testing was performed in an environmentally controlled (211 C, 555% RH) booth-partitioned room with a mixture of adjustable red light (<107.64 lumens) and green light (<107.64 lumens). Three texture attributes were assessed: ®rmness, ®brousness, and chewiness. In addition, beef identi®cation, moistness, and juiciness were assessed (Table 1). One orientation (``warm up'') sample was evaluated and discussed orally prior to the beginning of each testing session. All attributes, descriptions, and references were generated by the DTP panelists, who had access to reference materials during each test session (Table 1). Unsalted crackers and deionized rinse water were used between individual samples that were presented about 5 min apart. Attributes of the samples were evaluated using a structured 15-pt scale (0=none to 15=very intense) with 0.5 intervals (Table 1). Panelists were instructed to place each parallel and perpendicular sample horizontally on their molars for evaluation. Each treatment was given a 3-digit numerical code, and order of presentation was randomized for every test session and for panelists within test session. 2.3. Descriptive attribute sensory panel Sensory tenderness evaluations were conducted for all replications of each muscle over a 7-week period using a 8±10-member, trained, DA panel. Panelists were
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Table 1 Descriptive sensory texture pro®le panel attribute de®nitions Juiciness
The amount of liquid expressed from the sample during the ®rst and second chews Reference: Fresh Tokay (red) seedless grapes=12; Beef Brisket=10 Grapes were sliced in half lengthwise and evaluated with skin side down to bottom molars. Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Moistness of mass
The amount of liquid observed in the mass after 7 chews with the molar teeth. (midpoint juicy) Reference: Chicken Breast=5; Beef Brisket=9.0 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish. It was allowed to cool and then cut into 1.27 cm cubes and served warm Prep: Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Firmness
The amount of force required to bite through the sample with the molar teeth. Measured by placing the sample between the molars and biting through during the 1st and 2nd chew until molars meet Reference: Wonder English Mun=5; Lender's Bagel (top)=12, Beef Brisket=14.5 Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
Fibrousness Filaments or strands of muscle tissue Reference: Chicken Breast=10 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish, allowed to cool, then cut into 1.27 1.27 cm cubes, and served warm Chewiness
The number of chews necessary to reduce the sample to a consistency ready for swallowing Reference: Chicken Breast=10 Fresh chicken breast was microwaved to an internal temperature of 82 C in a covered Pyrex dish, allowed to cool, cut into 1.271.27 cm cubes, and served warm
Beef ID (¯avor)
The intensity with which the sample is recognized as distinctly beef lean muscle tissue rather than another type of protein product Reference: Beef Brisket=13.5 Brisket was baked in an oven at 163 C to an internal temperature of 70 C on a broiler pan, cut into 2.541.27 cm pieces, and served hot
screened, trained, and evaluated prior to the initiation of the study according to AMSA (1995) guidelines. This procedure required several weeks. The same procedures for thawing and cooking were used as for the DTP panel. Descriptive testing was performed in the same environmentally controlled (211 C, 555% RH), booth-partitioned room as described for the DTP panel. One orientation (``warm up'') sample was evaluated and discussed orally prior to the beginning of each testing session. No more than eight samples representing two replications of the four treatment combinations of one muscle were presented in one test session in order to minimize panelist fatigue. Each sample was represented by two cubes. Five attributes were assessed: myo®brillar tenderness, connective tissue amount, juiciness, beef ¯avor intensity, and overall tenderness (Table 2). The same procedures for cube removal were used as for the DTP panel. Unsalted crackers and deionized rinse water were used between individual samples that were presented about 2 min apart. Samples were evaluated for the ®ve attributes using an 8-point number scale and scored to the nearest .5 (Table 2). Order of presentation was randomized for every test session. Panelists were instructed to place each parallel and perpendicular cube horizontally on their molars for evaluation. 2.4. Statistical analyses The statistical design was a type of split plot design. Statistical analysis of DA and DTP panel data was performed by using PROC MIXED procedure of SAS1
(1994). The analysis of variance model for individual panel attributes consisted of the main eects and interaction for muscle type and cube plus error terms for panelists, cubes within a muscle type, steaks within a muscle, and sensory cubes within a steak. Pearson correlation coecients were calculated among the DA and DTP panel data by using the SAS1 system 3. Results and discussion The DTP panel detected dierences (p<0.05) among replications (muscles from dierent carcasses) for each muscle (LL and ST) for each of the six attributes evaluated (chewiness, beef identi®cation, ®brousness, ®rmness, moistness, and juiciness) (Table 3). No dierences (p>0.05) occurred among DTP panelists for any of the six attributes (no panelist eect), and there was no (p>0.05) panelist by replication eect. These results suggest that the panelists could detect dierences consistently. The DA panel also detected dierences (p<0.05) among replications for each muscle (LL and ST) for each of the ®ve attributes evaluated (juiciness, myo®brillar tenderness, connective tissue amount, overall tenderness, and beef ¯avor intensity) (Table 4). However, a panelist eect (p<0.05) occurred for each of the ®ve attributes. In addition, a panelist by replication eect (p<0.05) occurred, suggesting that panelists were not consistent in their evaluations. The longer time interval for the DA panel evaluations (7 week) than for the DTP panel evaluations (3 weeks) could partially
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Table 2 Descriptive attribute sensory panel 8-pt number scale de®ned Attributes Myo®brillar tendernessa
Juicinessb
Beef ¯avor intensityc
Connective tissue amountd
Overall tendernesse
1. Extremely tough 2. Very tough 3. Moderately tough 4. Slightly tough 5. Slightly tender 6. Moderately tender 7. Very tender 8. Extremely tender
1. Extremely dry 2. Very dry 3. Moderately dry 4. Slightly dry 5. Slightly juicy 6. Moderately juicy 7. Very juicy 8. Extremely juicy
1. Extremely bland 2. Very bland 3. Moderately bland 4. Slightly bland 5. Slightly intense 6. Moderately intense 7. Very intense 8. Extremely intense
1. Abundant 2. Moderately abundant 3. Slightly abundant 4. Moderate 5. Slight 6. Traces 7. Practically none 8. None
1. Extremely tough 2. Very tough 3. Moderately tough 4. Slightly tough 5. Slightly tender 6. Moderately tender 7. Very tender 8. Extremely tender
a b c d e
The perception of how tough or tender the myo®brillar component of that sample is. The amount of liquid expressed from the sample during the initial chews. The intensity with which the beef sample is recognized as distinctly beef lean tissue rather than another species of meat. The amount of connective tissue remaining in the palate upon completion of mastication, prior to swallowing. The perception of how tough or tender a meat sample is at the completion of mastication.
Table 3 Descriptive texture pro®le (DTP) sensory panel and descriptive attribute (DA) sensory panel analysis of variance for replication, panelist, and panelistreplication eects Attribute
Replication Panelist Panelist X (muscle) eect eect replication eect
DTP sensory panel Chewiness Beef identi®cation Fibrousness Firmness Moistness Juiciness
Ya Y Y Y Y Y
Nb N N N N N
N N N N N N
DA sensory panel Juiciness Myo®brillar tenderness Connective tissue amount Overall tenderness Beef ¯avour intensity
Y Y Y Y Y
Y Y Y Y Y
Y Y Y Y Y
a b
Y=signi®cant eect (p<0.05). N=no signi®cant eect (p>0.05).
explain the lower consistency. Although descriptive analysis methods have been in use for decades, researchers have sought ways to obtain detailed descriptions with less training and practice for panelists (Civille, 1994). Oreskovich (1994) compared results from a conventionally trained descriptive panel to results from a free-choice, pro®ling panel for a ¯avor and texture analysis of pork. She concluded that the free-choice panel could discriminate and describe dierences in pork treatment eects but the free-choice method did not describe attributes that characterize the unique properties of food. These results further support those from a study conducted by Chambers and Smith (1993), who found that training may be more important than experience for increased ``reproducibility'' in panelists. Each of our panels was experienced in sensory testing of
meat; however, the DTP panel was more highly trained than the DA panel, resulting in greater consistency. The dierences in scales should not have been a factor because Lawless and Malone (1986) used various scales with trained panelists and found no eect of the dierent scales. In addition, Chambers and Wolf (1996) stated that dierences in scales with trained panels did not signi®cantly aect responses. The DTP panel detected dierences (p<0.05) between cubes taken parallel with the muscle ®ber orientation and cubes taken perpendicular to the steak cut surface in the LL muscle for the attributes of chewiness, beef identi®cation, ®brousness, and ®rmness (Table 4) because muscle ®ber orientation was quite dierent. However, neither muscle ®ber orientation resulted in consistently higher or lower values. The attributes of moistness and juiciness for which the panel did not detect dierences (p>0.05, Table 4) probably do not have any relationship with muscle ®ber orientation. For the ST muscle, a dierence was detected between muscle ®ber orientation only for beef identi®cation. We have no logical explanation for this observation because the orientation of muscle ®bers essentially was the same for parallel and perpendicular cubes. The fact that the DTP panel was sensitive (p<0.05) to muscle ®ber orientation for attributes related to LL tenderness implies that samples taken parallel with the muscle ®ber orientation or perpendicular to the cut steak surface might make a dierence in the interpretation of results. The DA panel scored cubes lower (6.1 vs 6.3 and 6.3 vs 6.5, respectively; p<0.05) for the attributes of myo®brillar tenderness and overall tenderness (less tender) when they were taken parallel to the muscle ®ber orientation than when they were taken perpendicular to the steak cut surface in the LL muscle (Table 4). The attributes of juiciness and beef ¯avor intensity for which the DA panel did not detect any dierences (p>0.05, Table 4) probably are not dependent upon muscle ®ber orientation. For the
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Table 4 Descriptive texture pro®le (DTP) and descriptive attribute (DA) sensory panel interactions between parallel and perpendicular samples for each attribute within each muscle (Longissimus and Semitendinosus) Treatments Longissimus
Semitendinosus
Attribute
Parallel
Perpendicular
Parallel
Perpendicular
DTP sensory panela Chewiness Beef identi®cation Fibrous Firmness Moistness Juiciness
7.9c 10.9c 9.3c 7.6c 8.3c 8.8c
7.6d 10.6d 8.9d 7.3d 8.4c 8.7c
8.3c 9.8c 9.5c 8.4c 7.0c 7.1c
8.4c 9.4d 9.5c 8.4c 7.1c 7.2c
DA sensory panelb Juiciness Myo®brillar tenderness Connective tissue amount Overall tenderness Beef ¯avour intensity
5.5c 6.1c 6.6c 6.3c 5.7c
5.5c 6.3d 6.7c 6.5d 5.6c
4.9c 5.6c 5.4c 5.4c 5.2c
5.1d 5.8d 5.5c 5.6d 5.2c
a
DTP scale, 0=none to 15=very intense. DA scale, 1=extremely dry, extremely tough, abundabunt, extremely tough, and extremely bland; 8=extremely juicy, extremely tender, none, extremely tender, extremely intense. c Means in the same row within a muscle lacking a common superscript letter dier (p<0.05). d Means in the same row within a muscle lacking a common superscript letter dier (p<0.05). b
ST muscle, the DA panel scored perpendicular cubes higher (p<0.05) for juiciness, myo®brillar tenderness, and overall tenderness, but the magnitude of these differences was small and may not be of practical importance because orientation essentially is the same for both cubing methods. 3.1. Correlations between DTP panel attributes and DA sensory panel attributes Correlation coecients were calculated between attributes evaluated by the DTP panel and attributes evaluated by the DA panel for each treatment combination (LL parallel cubes, LL perpendicular cubes, ST parallel cubes, and ST perpendicular cubes) (Table 5). For LL samples that were taken parallel with the muscle ®ber orientation, the DTP and DA panel attributes that were correlated (p<0.05) were moistness with juiciness (r=0.51), moistness with myo®brillar tenderness (r=0.51), moistness with overall tenderness (r=0.51), ®rmness with myo®brillar tenderness (r=ÿ0.61), ®rmness with connective tissue amount (r=ÿ0.76), and ®rmness with overall tenderness (r=ÿ0.62). For LL cubes that were taken perpendicular to the steak cut surface, the DTP panel attributes and the DA panel attributes that were correlated (p<0.05) were: juiciness with juiciness (r=0.54), juiciness with myo®brillar tenderness (r=0.55), juiciness with overall tenderness (r=0.53), moistness with juiciness (r=0.55), moistness with myo®brillar tenderness (r=0.52), moistness with overall tenderness (r=0.50), ®rmness with
juiciness (r=ÿ0.68), ®rmness with myo®brillar tenderness (r=ÿ0.73), ®rmness with connective tissue amount (r=ÿ0.67), ®rmness with overall tenderness (r=ÿ0.69), chewiness with juiciness (r=ÿ0.67), chewiness with myo®brillar tenderness (r=ÿ0.68), chewiness with connective tissue amount (r=ÿ0.60), and chewiness with overall tenderness (r=ÿ0.69) (Table 5). These correlations show that the DTP panel trait of ®rmness was highly related to the DA panel tenderness traits and that moistness and juiciness were positively related to tenderness traits, regardless of muscle ®ber orientation. However, these results show that a greater number of traits were correlated more highly (r50.50 and r4ÿ0.50) when cubes were removed perpendicular to the steak cut surface than when removed parallel with the muscle ®ber orientation. Otremba, Dikeman, Hilliken, Stroda, Unruh and Chambers (1999) reported that correlations between DTP and DA panel evaluations and Warner-Bratzler shear force for the LL muscle were higher when cores were removed perpendicular to the steak cut surface than when removed parallel to the muscle ®ber orientation. These results contradict those of Poste, Butler, Mackie, Agar and Thompson, (1993) that parallel cores were slightly better than perpendicular cores for detecting treatment dierences and achieving high correlation values between WarnerBratzler shear values and sensory panel evaluations. For ST samples that were taken parallel to the muscle ®ber orientation, the DTP and DA panel attributes that were correlated (p<0.05) were: ®rmness with myo®brillar tenderness (r=ÿ0.69), ®rmness with connective
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Table 5 Correlations between descriptive texture pro®le (DTP) sensory panel attributes and descriptive attribute (DA) panel attributes for each treatment combination (Longissimus parallel, Longissimus perpendicular, Semitendinosus parallel, and Semitendinosus perpendicular)a Treatments DTP attribute vs DA attribute
Longissimus parrallel r
Longissimus perpendicular r
Semitendinosus parallel r
Semitendinosus perpendicular r
Juiciness/juiciness Juiciness/myo®brillar tenderness Juiciness/connective tissue amount Juiciness/overall tenderness Juiciness/beef ¯avor intensity Moistness/juiciness Moistness/myo®brillar tenderness Moistness/connective tissue amount Moistness/overall tenderness Moistness/beef ¯avor intensity Firmness/juiciness Firmness/myo®brillar tenderness Firmness/connective tissue amount Firmness/overall tenderness Firmness/beef ¯avor intensity Fibrousness/juiciness Fibrousness/myo®brillar tenderness Fibrousness/connective tissue amount Fibrousness/overall tenderness Fibrousness/beef ¯avor intensity Chewiness/juiciness Chewiness/myo®brillar tenderness Chewiness/connective tissue amount Chewiness/overall tenderness Chewiness/beef ¯avor intensity Beef identi®cation/juiciness Beef identi®cation/myo®brillar tenderness Beef identi®cation/connective tissue amount Beef identi®cation/overall tenderness Beef identi®cation/beef ¯avor intensity
0.39 0.49 0.48 0.49 0.19 0.51 0.51 0.49 0.51 0.15 ÿ0.45 ÿ0.61 ÿ0.76 ÿ0.62 ÿ0.24 ÿ0.30 ÿ0.42 ÿ0.32 ÿ0.39 0.01 ÿ0.19 ÿ0.11 ÿ0.24 ÿ0.09 0.28 0.38 0.19 0.25 0.33 0.30
0.54 0.55 0.36 0.53 0.49 0.55 0.52 0.33 0.50 0.44 ÿ0.68 ÿ0.73 ÿ0.67 ÿ0.69 ÿ0.39 ÿ0.11 ÿ0.19 ÿ0.17 ÿ0.24 ÿ0.24 ÿ0.67 ÿ0.68 ÿ0.60 ÿ0.69 ÿ0.47 0.35 0.25 0.34 0.29 0.38
ÿ0.06 ÿ0.19 ÿ0.38 ÿ0.24 ÿ0.01 ÿ0.03 ÿ0.14 ÿ0.38 ÿ0.21 ÿ0.01 ÿ0.33 ÿ0.69 ÿ0.58 ÿ0.65 ÿ0.38 ÿ0.43 ÿ0.47 ÿ0.35 ÿ0.39 ÿ0.38 ÿ0.27 ÿ0.49 ÿ0.28 ÿ0.40 ÿ0.31 0.27 0.28 ÿ0.10 ÿ0.04 ÿ0.03
0.27 0.18 ÿ0.34 ÿ0.47 0.24 0.29 0.22 ÿ0.29 0.01 0.30 ÿ0.33 ÿ0.65 ÿ0.54 ÿ0.66 ÿ0.63 ÿ0.50 ÿ0.59 ÿ0.33 ÿ0.50 ÿ0.42 ÿ0.40 ÿ0.61 ÿ0.12 ÿ0.46 ÿ0.65 ÿ0.07 ÿ0.22 ÿ0.50 ÿ0.50 ÿ0.52
a
Correlations 5 0.50 r 4 ÿ0.05 are signi®cant (p<0.05).
tissue amount (r=ÿ0.58), and ®rmness with overall tenderness (r=ÿ0.65) (Table 5). For ST samples that were taken perpendicular to the steak cut surface, the DTP panel attributes and the DA panel attributes that were correlated (p<0.05) were: ®rmness with myo®brillar tenderness (r=ÿ0.65), ®rmness with connective tissue amount (r=ÿ0.54), ®rmness with overall tenderness (r=ÿ0.66), ®brousness with myo®brillar tenderness (r=ÿ0.59), ®brousness with overall tenderness (r=ÿ0.66), chewiness with myo®brillar tenderness (r=ÿ0.61) (Table 5). These correlations show that the DTP panel trait of ®rmness was highly related to the DA panel tenderness traits regardless of muscle ®ber orientation. Again, a greater number of traits were correlated more highly (r>0.50) when cubes were removed perpendicular to the steak cut surface than when removed parallel with the muscle ®ber orientation. Otremba et al. (1999) reported that correlations between DTP and DA panel evaluations and Warner-Bratzler shear force for the LL muscle were
higher when cores were removed perpendicular to the steak cut surface than when removed parallel to the muscle ®ber orientation. Our results and those of Otremba et al. suggest that removing cubes perpendicular to the steak cut surface may be the preferred method for sensory panel evaluation. The fact that the DTP panel attributes of juiciness and moistness were signi®cantly correlated to the DA panel attributes of myo®brillar tenderness and overall tenderness implies that as the DTP panel's perception of juiciness increased, the DA panel's perception of tenderness increased, indicating that juiciness and tenderness are positively related. The DTP panel attributes of juiciness and moistness also were correlated (p<0.05) to the DA panel attribute of juiciness in the LL muscle. This implies that the DTP attributes of juiciness and moistness and the DA attribute of juiciness are measuring a similar attribute. Negative correlations (p<0.05) occurred between the attributes of ®rmness with myo®brillar tenderness,
M.M. Otremba et al. / Meat Science 54 (2000) 325±332
®rmness with connective tissue amount, and ®rmness with overall tenderness for all treatment combinations (LL parallel, LL perpendicular, ST parallel, and ST perpendicular) (Table 5). This ®nding indicates that the DTP panel's attribute of ®rmness is most likely measuring the same sample qualities that are being measured in the DA panel attributes of myo®brillar tenderness, connective tissue amount, and overall tenderness. The negative correlations occurred because on the DTP panel's 15-point scale, an increase in ®rmness score means a decrease in tenderness (sample is getting tougher), whereas on the DA panel's 8-point scale, an increase in score implies an increase in tenderness. Even though the DTP panel attribute of ®brousness was correlated signi®cantly to the DA panel attributes for the ST perpendicular samples, low correlations were found over the remaining treatment combinations, indicating that the DTP attribute of ®brousness is not related very well to DA panel attributes (Table 5). The DTP panel attribute of chewiness was correlated (P<0.05) with some of the DA panel's attributes related to tenderness, but mainly in LL samples, implying that DTP chewiness is similar to DA attributes associated with tenderness. The DTP attribute of beef identi®cation was correlated signi®cantly to some DA tenderness-related attributes in ST perpendicular samples only, implying that as tenderness was perceived to be greater by the DA panel, ¯avor was perceived to be higher by the DTP panel (Table 5). This could be what is sometimes referred to as the ``halo'' eect described by Howard (1972) and Chambers and Wolf (1996), meaning that as the perception of one trait increases the perception of one or more other traits increases without a cause and eect. However, for our ST parallel, LL parallel, and LL per-
331
pendicular samples, not many signi®cant correlations occurred among the DTP attribute of beef identi®cation and the DA panel attributes, implying that the DTP panel attribute of beef identi®cation (which measures ¯avor) is unrelated to most of the DA panel attributes, even beef ¯avor intensity. One would assume that the ¯avor assessment by each panel would be related highly. Chambers et al. (1981) reported that for such complex sensory characteristics as ¯avor, highly trained and experienced panelists may have less random error than panelists with less experience or training. Because panelist eect or panelistreplication eect did not occur for the DTP panel but did for the DA panel, low correlations between beef identi®cation and beef ¯avor intensity might be expected. Or, the limited variability in ¯avor in our samples may have resulted in low correlations. On the other hand, the same panel and panelistreplication eects existed for DA panel attributes related to tenderness, but correlations with the DTP attribute of ®rmness were consistently high. Chambers et al. (1981) conducted a study comparing a highly trained, experienced panel of three people with a seven- or eight-member panel of semi-trained individuals. They found that the highly trained, experienced panel had lower residual error mean squares than did the semi-trained panel. We also found that our DTP panel had lower residual error mean squares than the DA panel. Chambers et al. also reported that the semitrained panel found signi®cant dierences in more characteristics than did the highly trained, experienced panel, but the highly trained, experienced panel found more main eect and interaction dierences in characteristics for which both panels detected signi®cant dierences. Both panels in our study were able to detect dierences among replications (Tables 3 and 4).
Table 6 Correlations among descriptive texture pro®le (DTP) sensory panel attributes and among descriptive attribute (DA) sensory panel attributes for pooled parallel and perpendicular cores and longissimus and semitendinosus musclesa DTP sensory panel attributes
r
Juiciness/moistness Juiciness/®rmness Juiciness/®brousness Juiciness/chewiness Juiciness/beef identi®cation Moistness/®rmness Moistness/®brousness Moistness/chewiness Moistness/beef identi®cation Firmness/®brousness Firmness/chewiness Firmness/beef identi®cation Fibrous/chewiness Fibrous/beef identi®cation Chewiness/beef identi®cation
0.98 ÿ0.58 ÿ0.50 ÿ0.65 0.70 ÿ0.57 ÿ0.53 ÿ0.66 0.69 0.55 0.76 ÿ0.33 0.69 ÿ0.32 ÿ0.48
a
Correlations 5 0.50 r 4 ÿ0.05 are signi®cant (p<0.05).
DA sensory panel attributes
r
Juiciness/myo®brilliar tenderness Juiciness/connective tissue amount Juiciness/overall tenderness Juiciness/beef ¯avor intensity Myo®brillar/connective tissue Myo®brillar/overall tenderness Myo®brillar/beef ¯avor intensity Connective tissue amount/overall tenderness Connective tissue amount/beef ¯avor intensity Overall tenderness/beef ¯avor intensity
0.69 0.55 0.69 0.54 0.72 0.93 0.58 0.91 0.56 0.64
332
M.M. Otremba et al. / Meat Science 54 (2000) 325±332
3.2. Correlations among attributes within each panel
References
Correlation coecients also were calculated among attributes evaluated within each panel (Table 6). For the DTP panel, signi®cant correlations existed for almost every attribute with another, except for ®rmness with beef identi®cation (r=ÿ0.33) and ®brousness with beef identi®cation (r=ÿ0.32). This may have been due to the fact that these attributes are measuring unrelated qualities of beef. Some attributes that were correlated more highly (r>0.70) were juiciness with moistness (r=0.98) and ®rmness with chewiness (r=0.76), probably because these attributes are measuring similar qualities of beef. For example, juiciness and moistness may be perceived as a similar characteristic by the panelists, hence resulting in such a high correlation. These high correlations raise the question of why two attributes that are so similar to each other are evaluated, when evaluating either one individually might give the same information. Correlation coecients also were calculated among attributes evaluated within the DA panel (Table 6). Correlations (p<0.05) greater than or equal to .54 were found among all attributes. Attributes that were correlated more highly (r>0.70) were found for myo®brillar tenderness with connective tissue amount (r=0.72), myo®brillar tenderness with overall tenderness (r=0.93), and connective tissue amount with overall tenderness (r=0.91). These attributes may be measuring similar characteristics, and(or) as the perception of one attribute increases or decreases, the perception of the other also increases or decreases.
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4. Implications Our results suggest that a highly trained descriptive texture pro®le sensory panel may be able to detect more subtle dierences among treatments because panelist variation may be less than in a trained descriptive attribute sensory panel trained according to the American Meat Science Association (1995) guidelines. Using cubes removed perpendicular to the steak cut surface might result in higher relationships among texture-related attributes between the two types of panels than using those removed parallel with muscle ®ber orientation. Flavor evaluation by either type of panel should not be expected to be related highly to other attributes or to the other panel. Both panels should be expected to be eective in detecting dierences among replications.