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Breed, slaughter weight and ageing time effects on sensory characteristics of lamb
MEAT SCIENCE Meat Science 69 (2005) 571–578 www.elsevier.com/locate/meatsci
Breed, slaughter weight and ageing time effects on sensory characteristics of lamb S. Martı´nez-Cerezo *, C. San˜udo, I. Medel, J.L. Olleta Department of Animal Production and Food Science, University of Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain Received 4 August 2004; received in revised form 10 October 2004; accepted 10 October 2004
Abstract The longissimus lumborum (right and left) from 180 entire male lambs were tasted by a nine-member trained taste panel. The samples were from lambs from three Spanish breeds; Rasa Aragonesa (local meat breed), Churra (local dairy breed) and Spanish Merino. Within breed, three slaughter live weights were considered (10–12, 20–22 or 30–32 kg) and meat was aged in a vacuum package for 1, 2, 4, 8 or 16 days. Panellists assessed a total of eight descriptors. Lamb odour and lamb flavour intensities increased with slaughter weight. However, fat flavour intensity was significantly influenced by breed, with the highest score for Rasa Aragonesa. Off-flavour intensity was influenced by breed and ageing, with higher scores for Rasa Aragonesa and longer ageing times. Tenderness and juiciness were influenced by all three effects (P 6 0.001, each) and there was a significant interaction between breed and slaughter live weight. Meat was juicier and more tender in the lightest Churra lambs, and in the Spanish Merino lambs for the heavier weight animals. Tenderness and juiciness increased with ageing. The best quality flavour was for the Spanish Merino and the intermediate and heavier lambs. 2004 Elsevier Ltd. All rights reserved. Keywords: Odour; Tenderness; Juiciness; Flavour; Taste panel
1. Introduction Meat is a complex product and, as a result, its quality evaluation is not always easy. Many studies on meat and meat products have been designed to develop instrumental or physico-chemical methods to replace the sensory test, mainly because sensory methodologies have been seen as subjective, expensive and tedious (Risvik, 1994). However, although instrumental methods have the advantages of being objective and cheaper, at the moment, they only provide partial explanations of the complex set of interactions that occur when cooked meat is smelled, chewed (Thompson, 2002) and swallowed. This partial explanation of *
Corresponding author. Tel.: +34 976761000x4148; fax: +34 976761590. E-mail address: [email protected] (S. Martı´nez-Cerezo). 0309-1740/$ - see front matter 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2004.10.009
instrumental analysis can be clearly observed, for example, in flavour and odour determinations. Thus, although the chemical compounds involved in odour and flavour development are relatively easy to obtain using GC–MS and GC–sniffing techniques (Nitz, Kollmannsberger, & Drawert, 1989; Young, Berdague´, Viallon, Rousset-Akrim, & Theriez, 1997), these isolated compounds do not give a global idea about the overall flavour and odour (blends of many components) and its preference by consumers. On the other hand, sensory juiciness scores are difficult to predict from instrumental measurements of meat texture or cooking losses (Thompson, 2002). During the last decades, the development of sensory and statistical methods has helped to overcome the possible subjectivity problems in sensory analyses. As a result, sensory studies are useful when a complete evaluation of meat quality has to be made.
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A great number of pre- and post-slaughter factors influence lamb meat quality (San˜udo, Sa´nchez, & Alfonso, 1998a). Among pre-slaughter factors, the influence of breed and slaughter weight on lamb sensory characteristics is unclear. In some studies, they appear to affect some organoleptic scores (Jeremiah, Tong, & Gibson, 1998; San˜udo et al., 1997), but in others they have no effect (Solomon, Kemp, Moody, Ely, & Fox, 1980; Suarez, Busetti, Garriz, Gallinger, & Babinec, 2000). Similarly, in a review by Crouse (1983), some authors found flavour differences among breeds or slaughter weights while others did not. These differences may be explained by differences in slaughter weights when breed effect was compared and because, at the same slaughter weight, breeds have different levels of maturity. Among post-slaughter factors, ageing time has been mainly associated with textural parameters (Bouton & Harris, 1972; Hopkins & Thompson, 2001; Shorthose, Powell, & Harris, 1986; Wheeler & Koohmaraie, 1994). Jaime, Beltra´n, Cen˜a, Lo´pez-Lorenzo, and Roncale´s (1992) found that increasing ageing time from 1 to 7 days made lamb meat more tender, according to a 10-member semi-trained taste panel. However, although some authors have studied the effects of ageing time on lamb, many avoid sensory analyses or include a limited number of short ageing times, although new market requirements (packaging) will lead to longer ageing times. No studies, up to date, have been performed to assess the influence of breed and slaughter weight on the evaluation of lamb meat characteristics throughout ageing. In this study, we evaluated the effect of breed and slaughter live weight (according to similar market weights for Churra, 10–12 kg; Rasa Aragonesa, 20–22 kg; and Spanish Merino, 30–32 kg) throughout ageing, considering several sensory characteristics of lamb meat assessed by a trained taste panel.
2. Materials and methods 2.1. Meat samples Samples were taken from 180 entire male lambs from three Spanish breeds: 60 Rasa Aragonesa lambs (local meat breed), 60 Churra lambs (local dairy breed) and 60 Spanish Merino lambs (specialised meat breed). Within breed, three slaughter live weights were considered: 10–12 kg (suckling lambs), 20–22 kg (light lambs) and 30–32 kg (early fattening lambs). Then, 20 lambs were analysed within each breed and slaughter weight. Each breed has an official quality label associated with a specific production system and environment that have been maintained throughout the years (including specifications about breed, feeding system, slaughter age-weight and fatness score). The European quality
label (PGI) for the Rasa Aragonesa is called Ternasco de Arago´n (European Union, 1996) and Lechazo de Castilla y Leo´n for the Churra (European Union, 1999). Cordero de Extremadura is the regional quality label for the Spanish Merino (Diario Oficial de Extremadura, 1995). The lightest lambs in each breed (unweaned) were slaughtered at the region of origin, Rasa Aragonesa lambs in Arago´n (NE Spain), Churra lambs in Castilla-Leo´n (central Spain) and Spanish Merino lambs in Extremadura (SW Spain). All the rest of the lambs were transported from those regions to the same collecting place and divided into two lots to be slaughtered at different weights. Lambs were fattened indoors with concentrate (43.3% barley, 25.0% corn, 22.3% soya-44, 4.0% acid whey, 2.1% calcium carbonate, 2.0% beet molasses, 0.5% palm oil, 0.4% mineral mix and 0.4% plain salt) and cereal straw ad libitum in the same facilities. Every week, lambs were individually weighed until they reached the target slaughter live weight. All lambs were slaughtered using standard commercial procedures, according to welfare codes of practice. Then, carcasses were suspended by the Achilles tendon and refrigerated [12 C (±2 C) for 6 h, +2 C (±2 C) for 18 h]. At 24 h post-mortem, carcasses were cut into two halves and the longissimus lumborum (without subcutaneous fat) was excised from both half carcasses (360 samples in total), wrapped in aluminium foil, vacuum-packaged into polyethylene bags, randomly aged for 1, 2, 4, 8 or 16 days at 3 C (±1 C) (samples from the same carcass were not included in the same ageing group) and were frozen at 20 C until further analysis. 2.2. Sensory evaluation A nine-member trained sensory panel was used to evaluate the samples using a quantitative descriptive analysis. Assessors were trained (ISO 8586-1:1993) in sensory profiling of lamb meat during 10 training sessions during which they developed a common vocabulary to evaluate sensory characteristics of lamb meat and agreed upon a list of descriptors and their definitions. After thawing in tap water, 2 cm-thick slices of each longissimus lumborum were cooked on a pre-heated double hot-plate grill at 200 C until the internal temperature reached 70 C. Then, they were cut into nine portions (free of visible connective tissue), which were wrapped in aluminium foil and identified with a single random three-digit code. Samples were kept warm until serving within 10 min after cooking. Sensory tests were performed, in 29 sessions, in a controlled sensory analysis laboratory (ISO 8589:1988) with individual booths, which were provided with red light to mask any differences in meat colour. In each session, panellists received sets of 3 samples representing the
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flavour quality from 1 = unpleasant to 100 = very pleasant.
three different breeds (same slaughter weight and ageing time), 3 samples representing the three different slaughter weights (same breed and ageing time) and/ or sets of 4 samples representing four out of the five different ageing times (same breed and slaughter weight), until a maximum of 13 samples per session. Meat was served following a randomised design for order and carry over effects, and panellists were asked to eat a bit of bread and to drink a bit of still water at the beginning of the sensory evaluation and between samples to try to make the palate conditions similar for each sample. Panellists evaluated the meat samples following the list of descriptors defined during the training period (Table 1). Each attribute was quantified using an unstructured line scale of 100 points. Odour was scored immediately after opening the aluminium foil parcel (1 = no odour, 100 = very intense odour). Tenderness was scored from 1 = very tough to 100 = very tender, and juiciness from 1 = very dry to 100 = very juicy. Lamb flavour, fat flavour and off-flavour were rated from 1 = no flavour to 100 = very intense flavour, and
2.3. Statistical analyses From the 360 samples, 8 replicates and 72 judgements were obtained per breed, slaughter weight and ageing time to determine the effects of breed, slaughter live weight and ageing time. Data were analysed using SPSS 8.0 for Windows. The significance of effects (breed, slaughter weight and ageing time) and their respective interactions were obtained using the General Linear Model procedures. The panellist effect was significant for all the sensory attributes (P < 0.001), as is quite common in sensory work due to the different uses of scale (Rousset-Akrim, Young, & Berdague´, 1997) and will not be considered further. Means and standard deviations were computed for every variable. The DuncanÕs multiple range test was used to show significant differences among means. Differences were considered significant at the P 6 0.05 level.
Table 1 Definition of descriptors for the quantitative descriptive sensory analyses
3. Results and discussion
Descriptor
Definition
3.1. Global results
Lamb odour intensity Off-odour intensity
Odour associated with the species Undesirable or less desirable odours in lamb meat, such as wool, stall, liver, ammonia, sulphur, rancid, etc.
Tenderness
Ease of chewing the sample between the molar teeth Global juiciness (initial + sustained) perceived during chewing
Juiciness Lamb flavour intensity Fat flavour intensity Off-flavour intensity
Flavour quality
Breed and ageing time did not have a significant influence on odour (Table 2). However, slaughter live weight modified the lamb odour intensity (P < 0.05), without having any influence on the off-odour intensity. There were no significant interactions among factors. Other studies have also failed to find a relationship between breed and odour intensity, including Crouse, Ferrell, and Cross (1983) in Suffolk and Columbia sired lambs out of Finn · Rambouillet ewes, Suarez et al. (2000) in Corriedale, Corriedale · Pampita and Pampita lambs or Hoffman, Muller, Cloete, and Schmidt (2003) using six crossbreeds.
Flavour associated with the species Flavour associated with fat Undesirable or less desirable flavours in lamb meat, such as wool, stall, liver, ammonia, sulphur, rancid, etc. Flavour preference
Table 2 F-values and significance for the sensory descriptors evaluated in the longissimus lumborum of lamb, according to the studied factors: breed (B), slaughter live weight (SLW), ageing time (A) and their interactions Descriptor
Breed
Slaughter live weight
Ageing time
B · SLW
B·A
SLW · A
B · SLW · A
Lamb odour intensity Off-odour intensity
n.s. n.s.
3.30* n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
Tenderness Juiciness
45.66*** 45.29***
26.07*** 18.27***
72.03*** 32.22***
22.51*** 18.86***
n.s. n.s.
n.s. n.s.
n.s. n.s.
Lamb flavour intensity Fat flavour intensity Off-flavour intensity Flavour quality
n.s. 6.17** 6.19** 27.69***
16.82*** n.s. n.s. 21.94***
n.s. n.s. 7.96*** n.s.
n.s. n.s. n.s. n.s.
n.s. n.s. 3.48*** n.s.
n.s. n.s. 2.63** n.s.
n.s. n.s. n.s. n.s.
n.s., Not significant differences. * P 6 0.05. ** P 6 0.01. *** P 6 0.001.
17.6 (18.0) 19.5 (22.5) 15.5 (17.1) 16.6 (18.6) 15.2 (15.5) 14.8 (14.9) 17.2 (18.6) 15.9 (15.4) 16.5 (16.9) 17.7 (18.4) 13.6 (15.2) 14.0 (13.8) 19.1 (18.5) 17.0 (17.7) 14.6 (15.7) 16.0 (17.0) 13.6 (16.9) 15.1 (15.8) 14.8 (16.0) 15.7 (15.9) 15.5 (15.9) 15.6 (18.9) 14.7 (15.8) 13.4 (13.7) 13.8 (14.4) 15.2 (16.7) 12.7 (14.1) 16.2 (16.3) 16.6 (17.8) 16.7 (17.6) 19.7 (17.3) 18.7 (18.9) 14.7 (14.6) 14.3 (12.4) 13.7 (13.2) 14.0 (14.4) 15.1 (12.5) 17.0 (18.6) 16.1 (14.9) Off-odour intensity (1–100) RA 18.2 (18.0) CH 15.8 (16.2) ME 14.1 (16.4)
16.7 (16.8) 14.0 (14.5) 16.0 (16.9)
51.7 (19.1) 52.5 (18.3) 49.1 (20.5) 49.2 (19.3) 50.7 (18.0) 50.0 (19.6) 51.6 (18.9) 49.2 (21.0) 50.1 (19.1) 51.5 (17.2) 51.4 (18.2) 49.8 (18.5)
8 4 2 1
50.9 (16.7) 50.5 (19.9) 47.8 (18.8) 50.3 (21.1) 50.6 (18.4) 51.1 (17.0) 48.5 (21.8) 49.4 (18.0) 50.9 (19.1) 50.7 (20.1) 47.3 (18.0) 51.5 (17.4) 49.9 (20.5) 49.5 (16.2) 49.8 (17.7) 50.7 (18.4) 51.3 (15.8) 49.7 (19.0) 47.2 (20.9) 47.4 (20.6) 51.4 (20.4) 45.4 (20.2) 47.7 (20.6) 48.8 (19.4) 50.7 (20.8) 48.3 (20.2) 47.0 (18.2) Lamb odour intensity (1–100) RA 47.7 (20.9) 51.1 (18.5) CH 46.6 (18.7) 47.8 (19.9) ME 47.6 (18.8) 51.7 (17.4)
30–32 kg (Early fattening lambs)
16 8 4 2 1
20–22 kg (Light lambs)
16 8 4
In suckling lambs (Table 4), meat was more tender and juicy for Churra at any ageing time. This could be due to differences in precocity among breeds, since Churra matures earlier (lower adult live weight and dairy breed) and higher levels of fat could make the meat more tender and juicy (Hawkins et al., 1985; Paul, Torten, & Spurlock, 1964). However, at higher slaughter weights, Spanish Merino had the highest scores for both parameters. This tendency for Merino meat to be more tender was also observed by San˜udo et al. (2003) in a comparison of different European commercial lambs using trained panels from six countries.
2
3.3. Textural attributes
10–12 kg (Suckling lambs)
Lamb odour intensity (Table 3) increased with slaughter live weight in Rasa Aragonesa and Churra but not in Spanish Merino. Although, in this latter breed, lamb odour intensity increased from the suckling lambs to the light lambs, the scores from 30–32 kg lambs were similar to 10–12 kg lambs. According to DuncanÕs test there were no significant differences among the weight groups, which is similar to Field, Williams, Ferrell, Crouse, and Kunsman (1978) and Carlucci, Napolitano, Girolami, and Monteleone (1999), who did not find significant differences in odour due to slaughter weight. Although it would be expected to find higher offodour intensities at longer ageing times, all ageing times had similar and very low scores, indicating that the preservation procedure was adequate.
1
3.2. Odour attributes
Ageing (days):
PanellistsÕ scores for tenderness and juiciness were significantly affected by the three factors considered (Table 2) but, considering the F values, ageing had more effect on tenderness than breed or slaughter live weight. Breed had the most important influence on juiciness. A significant effect of the breed by slaughter weight interaction was also observed. Lamb flavour was only significantly affected (P 6 0.001) by slaughter live weight (Table 2). Even though flavour and odour are related, flavour was more affected by slaughter weight. The fat flavour intensity was only influenced by breed (P 6 0.01). There were off-flavour differences due to breed (P 6 0.01) and ageing (P 6 0.001), which could mean that the panellists detected flavour better than odour. According to Rousset-Akrim et al. (1997), proteolysis products (peptides), which are some of the many compounds involved in off-flavour, are largely water soluble and have no significant vapour pressure, so the perception of flavour is more sensitive than odour. Flavour quality was affected by breed and slaughter weight (P 6 0.001, Table 2), but not by ageing.
16
S. Martı´nez-Cerezo et al. / Meat Science 69 (2005) 571–578 Table 3 Means (standard deviation) of the odour scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel
574
58.4ayr (18.2) 60.6abxs (16.7) 64.6bxyr (15.1) 59.4ayr (15.5) 57.2axrs (14.6) 62.2ayr (14.5) 58.8abyr (16.9) 55.8axrs (15.8) 61.7byr (15.9) 51.8axq (18.1) 53.4axqr (15.2) 60.6byr (12.8) a–c: Different superscripts represent significant differences among breeds (within slaughter live weight and ageing) (P 6 0.05). x–z: Different superscripts represent significant differences among slaughter live weights (within breed and ageing) (P 6 0.05). q–t: Different superscripts represent significant differences among ageing times (within slaughter live weight and breed) (P 6 0.05).
47.2axq (17.4) 48.6abxq (17.5) 53.5bxq (17.6) 56.7ayr (17.6) 60.7axr (15.7) 66.5byr (12.8) 52.5axqr (18.2) 55.8axqr (14.2) 64.2byqr (15.1) 56.4ayr (13.6) 58.4axqr (14.9) 67.2bzr (13.3) 50.4axq (15.4) 54.1axq (15.2) 62.2byqr (13.7) 46.9axq (16.6) 53.2bxq (17.9) 60.2cyq (15.3) 50.5axqr (16.5) 62.7bxr (15.0) 60.0bxs (14.0) 53.0axr (14.8) 60.3bxr (15.7) 55.3abxrs (15.9) 47.9axqr (17.2) 57.4bxqr (16.0) 47.6axq (17.2) Juiciness (1–100) RA 45.2axq (16.8) CH 53.1bxq (15.8) ME 49.4abxq (17.3)
50.1axqr (14.6) 58.4bxr (12.3) 50.6axqr (16.7)
70.0ayr (19.7) 72.4axt (17.9) 79.0bys (14.6) 69.2axr (18.1) 66.3axs (18.6) 72.1ayr (16.9) 68.4abyr (20.1) 65.4axrs (17.7) 73.1byr (17.5) 56.4axq (21.7) 59.4axqr (17.9) 71.8byr (14.2) 53.9axq (19.4) 55.3axq (19.5) 58.6axq (20.4) 73.3ayt (19.9) 73.2axs (14.6) 80.9byr (13.2) 62.6axrs (21.1) 65.0axqr (16.4) 77.5bzr (14.4) 64.7ays (17.8) 68.9axrs (18.2) 78.0byr (13.3) 56.9axqr (17.9) 60.3axyq (18.8) 71.3byq (13.3) 53.2axq (17.5) 59.1axq (20.6) 67.1byq (16.1) 59.9axr (18.4) 74.4bxs (17.1) 70.5bxs (15.6) 62.7axr (18.3) 70.9bxrs (19.6) 63.6axr (16.8) 57.8axr (15.9) 68.6bxrs (18.1) 56.1axq (19.3) 56.9axr (19.9) 66.1byr (18.6) 55.9axq (19.0)
16 8 4 2 1 16 8 4 2 1 16 8 4 2 1 Ageing (days):
Tenderness (1–100) RA 50.0axq (16.9) CH 57.0bxq (17.7) ME 53.6abxq (19.4)
30–32 kg (Early fattening lambs) 20–22 kg (Light lambs) 10–12 kg (Suckling lambs)
Table 4 Means (standard deviation) of the textural descriptor scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel
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On the other hand, the evolution of tenderness and juiciness (Table 4) varied with breed, as reported in the literature. Thus, in Rasa Aragonesa, tenderness and juiciness improved progressively as slaughter weight increased. Jeremiah et al. (1998) also observed this slaughter weight effect on overall tenderness for Canadian lambs from 31.8 to 76.8 kg. The opposite was observed in Churra lambs, where higher slaughter weights had less tender meat, as found by Lloyd, Slyter, and Costello (1981) in Targhee and Suffolk · Targhee animals at 54 and 64 kg slaughter weight, and by Oliveira, Silva, Freitas, and Paulino (2003) in Santa Ines lambs (38.83 ± 3.18 kg) and yearling muttons (52.97 ± 5.20 kg). Churra meat was also drier at higher slaughter weights. Spanish Merino meat did not adjust to any linear tendency, even though suckling lambs had lower scores for tenderness and juiciness than heavier lambs. Sensory results for tenderness were not the same as data for instrumental texture analysis from the same animals (raw meat-compression) (Martı´nez-Cerezo et al., 2005). Thus, for example, compression at 20% maximum compression was higher in the suckling lambs and increased with slaughter weight at 80% maximum compression. These discrepancies with sensory assessments could be due to differences in meat treatments, since meat for instrumental texture was raw, while meat for sensory analyses was grilled to a 70 C internal temperature, which produces a slight solubilisation of collagen and denaturation of myofibrillar proteins. There was a clear tenderisation effect produced by ageing (Table 4). Tenderness improved at longer ageing times for all the breeds and slaughter weights, with highest tenderness values at 16 days of ageing. Thus, from 1 to 16 days of ageing, the tenderness of meat samples from Rasa Aragonesa increased by almost 20%, 38% and 30%, Churra by 31%, 24% and 31% and Merino by 32%, 21% and 35% in suckling, light and early fattening lambs, respectively. Nevertheless, there were differences in tenderisation rates among breeds and slaughter live weights. In most cases tenderness at 4 days of ageing was considerably higher compared to 1 day of ageing. In six out of nine cases (three breeds · three slaughter weights), meat aged for 4 days was 65% as tender as meat aged for 16 days. Juiciness also increased with ageing, but the effect on tenderness was greater. Both textural parameters were higher at longer ageing times as a consequence of the degradation of muscle structure that reduces myofibrillar strength (Ouali, 1990) and could facilitate the release of meat juice during chewing. 3.4. Flavour attributes Flavour is one of the main characteristics in determining the acceptability of lamb meat for consumers
576 Table 5 Means (standard deviation) of the flavour scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel 10–12 kg (Suckling lambs) Ageing (days):
1
2
20–22 kg (Light lambs)
30–32 kg (Early fattening lambs)
8
16
1
2
4
8
16
1
2
4
8
16
Lamb flavour intensity (1–100) RA 54.7axqr 56.5axr (17.3) (13.4) CH 57.1axq 52.5axq (13.7) (14.3) ME 54.5axq 55.0axq (14.1) (14.7)
55.5axqr (14.0) 55.9axq (13.7) 54.0axq (14.8)
54.7axqr (12.7) 55.8axq (13.7) 53.7axq (12.9)
50.5axq (15.0) 55.6bxq (14.7) 55.7bxq (12.3)
55.7axq (13.6) 58.0axq (13.1) 56.9axq (14.3)
56.1axq (12.0) 58.0ayq (10.5) 56.3axq (12.7)
58.1axq (13.2) 56.8axq (12.1) 59.1ayq (14.8)
56.5axq (14.6) 57.3axq (13.9) 58.8ayq (15.5)
58.2ayq (12.1) 57.5axq (13.1) 59.5axq (14.3)
57.8axq (14.3) 58.2axq (15.1) 57.3axq (15.2)
56.6axq (16.8) 60.1ayq (13.3) 59.1axq (14.2)
60.0axq (15.1) 58.3axq (14.3) 59.6ayq (15.2)
58.7axq (12.8) 55.9axq (15.0) 58.2ayq (11.5)
58.2ayq (14.3) 58.2axq (14.0) 57.7axq (13.5)
Fat flavour intensity (1–100) RA 33.4axq (20.9) CH 27.8axq (20.7) ME 28.5axq (19.5)
31.1axq (19.0) 27.9axq (20.6) 29.6axq (17.6)
32.0axq (17.7) 29.8axq (18.9) 28.6axq (19.1)
30.2axq (18.3) 28.2axq (19.7) 26.7axq (17.2)
27.0axq (18.1) 25.8axq (19.5) 27.8axq (20.4)
29.1axq (16.6) 28.1axq (18.6) 26.2axq (18.3)
30.6axq (18.5) 27.2axq (19.8) 25.9axq (19.0)
29.2axq (18.2) 28.1axq (22.3) 26.0axq (19.3)
27.4axq (17.6) 30.1axq (21.8) 28.3axq (20.2)
27.5axq (18.8) 27.2axq (19.4) 27.4axq (21.1)
35.5bxr (19.3) 29.0axq (18.2) 28.2axq (19.0)
29.9axqr (20.1) 28.7axq (20.1) 27.3axq (19.2)
31.9axqr (19.7) 30.0axq (20.4) 26.8axq (19.7)
30.4axqr (19.9) 28.3axq (19.9) 28.2axq (20.2)
28.1axq (18.3) 27.2axq (19.4) 26.8axq (19.9)
Off-flavour intensity (1–100) RA 21.5axq (18.0) CH 21.0axq (18.2) ME 18.6axq (16.0)
20.7axq (16.9) 23.5axqr (19.2) 22.4axq (18.6)
18.9axq (15.9) 20.6axq (14.2) 23.5axq (21.4)
24.9axq (21.8) 20.9axq (17.3) 22.2axq (17.5)
38.5byr (23.7) 28.5axr (23.0) 24.0axq (19.1)
20.9axq (19.1) 20.0axq (16.7) 19.3axq (16.7)
20.3axq (15.6) 23.0axq (17.4) 23.1axq (18.0)
20.1axq (17.3) 21.8axq (18.0) 22.3axq (21.2)
23.2axq (19.2) 24.4axq (21.5) 25.5axq (21.2)
30.5bxr (22.3) 21.7axq (18.0) 23.8axq (20.1)
30.3byq (24.5) 21.6axq (18.7) 19.1axq (14.7)
23.0axq (19.2) 19.3axq (14.9) 22.1axq (19.3)
24.6axq (23.1) 24.5axq (17.9) 20.7axq (18.2)
24.0axq (20.8) 18.7axq (15.5) 22.9axq (18.2)
26.3axq (22.4) 25.1axq (21.1) 21.4axq (17.8)
Flavour quality (1–100) RA 48.3axr (17.0) CH 51.5axq (16.2) ME 53.1axq (15.7)
50.9axr (14.7) 51.1axq (15.7) 51.1axq (14.6)
51.8axr (13.8) 54.9axq (15.3) 51.2axq (17.0)
49.5axr (17.0) 51.5axq (16.5) 52.6axq (15.9)
41.5axq (18.8) 51.8bxq (20.9) 53.1bxq (16.7)
51.6axqr (17.0) 54.8abxq (18.0) 60.3byq (15.3)
50.8axqr (16.5) 53.3abxq (17.4) 57.4byq (17.3)
56.1abxr (14.6) 53.4axq (17.0) 60.2byq (16.8)
48.8axq (16.8) 51.5abxq (20.2) 57.3bxyq (18.9)
51.4ayqr (19.0) 57.3abxq (18.2) 60.2byq (17.4)
50.2axq (17.0) 53.7abxq (17.3) 56.5bxyq (16.0)
53.6axq (16.3) 55.2abxq (16.0) 59.9byq (16.8)
54.6axq (19.2) 53.7axq (17.7) 61.3byq (14.9)
53.5axq (18.1) 56.8axq (17.6) 58.4ayq (13.4)
53.5ayq (18.8) 55.8axq (18.3) 57.9axyq (15.8)
a,b: Different superscripts represent significant differences among breeds (within slaughter live weight and ageing) (P 6 0.05). x,y: Different superscripts represent significant differences among slaughter live weights (within breed and ageing) (P 6 0.05). q,r: Different superscripts represent significant differences among ageing times (within slaughter live weight and breed) (P 6 0.05).
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(Corcoran et al., 1999), especially in Mediterranean countries in Europe, where lighter lambs are preferred for their mild flavour. Lamb flavour was more intense for heavier lambs (Table 5). Overall values (considering all breeds and ageing times) were 54.8 ± 14.1, 57.5 ± 13.3 and 58.3 ± 14.3 for suckling, light and early fattening lambs, respectively. Jeremiah et al. (1998) also observed that lamb flavour intensity increased with age from 3–6 months to 6–9 months, but the differences were not significant. Rasa Aragonesa lambs (Table 5) had the strongest fat flavour intensity (30.19 ± 18.76, 28.22 ± 19.87, 27.48 ± 19.23, Rasa Aragonesa, Churra and Merino, respectively; considering all slaughter weights and ageing times). This is not directly related to fat quantity since, as shown in a previous paper (Martı´nez-Cerezo et al., 2005), Rasa Aragonesa only had slightly higher (not significant) intramuscular fat contents than the other breeds at 30–32 kg live weight. Therefore, breed differences in chemical composition and metabolism of lipids could probably explain this result, as reported by Sink (1979). Rasa Aragonesa (Table 5) had higher off-flavour intensity at 1 and 16 days of ageing, but breed differences within slaughter weight and ageing were not always significant. Ageing for long periods (16 days) increased off-flavour by more than 79% in the Rasa Aragonesa suckling lambs. Suckling lambs also had a stronger off-flavour at 16 days of ageing in the other studied breeds, which implies that meat from suckling lambs should not be aged as long. On the other hand, in general, at the other two slaughter weights, ageing for 4 days did not modify off-flavour intensity as much as after 16 days. As expected, Rasa Aragonesa had a slightly lower flavour quality (Table 5) since it had the highest fat flavour intensity and higher off-flavour intensity at 1 and 16 days of ageing. Spanish Merino had the highest scores. Panellists considered that light and early fattening lambs had better flavour quality than suckling lambs (Table 5). This is probably related to the background of the panellists (San˜udo et al., 1998b) because they are used to eating meat from lambs weighing between 20 and 24 kg. Since culture and previous experience have an important influence on taste preferences (Contreras, 1993), panellists probably rated with higher scores that type of lamb because they were accustomed to them and not to the characteristic milky taste of meat from suckling lambs.
4. Conclusions Breed and slaughter weight modified the sensory characteristics of lamb meat and, as a result, all meat quality labels in this species should include them in their specifications.
577
Ageing has an important effect on the sensory evaluation of lamb meat. In lambs with a slaughter weight of 10–12, 20–22 and 30–32 kg, 4 days of ageing seems to be enough to obtain high quality meat. However, ageing for longer periods (16 days) does not seem to decrease meat quality in light (20–22 kg) and early fattening (30–32 kg) lambs.
Acknowledgements The authors thank B. Panea, J.J. Pardos, M. Zatorre and S. Macı´e for their technical assistance and the trained panel members for their collaboration. This work has been made possible by financial help from the INIA (Project CAL00-003-C2-01). Soledad Martı´nez-Cerezo was supported by F.P.U. doctorate grant from the Ministerio de Educacio´n, Cultura y Deporte of Spain. References Bouton, P. E., & Harris, P. V. (1972). The effects of some postslaughter treatments on the mechanical properties of bovine and ovine muscle. Journal of Food Science, 37, 539–543. Carlucci, A., Napolitano, F., Girolami, A., & Monteleone, E. (1999). Methodological approach to evaluate the effects of age at slaughter and storage temperature and time on sensory profile of lamb meat. Meat Science, 52, 391–395. Contreras, J. (1993). Antropologı´a de la alimentacio´n. Barcelona: Eudema, pp. 96. Corcoran, K., Bernue´s, A., Manrique, E., Pacchioli, T., Baines, R. & Boutonnet, J.P. (1999). A system approach to quality assurance: consumer attitudes towards red meat. In Proceedings of seminar ‘‘production systems and product quality’’. FAO-CIHEAM. Crouse, J. D. (1983). The effects of breed, sex, slaughter weight, and age on lamb flavor. Food Technology, 37(5), 264–268. Crouse, J. D., Ferrell, C. L., & Cross, H. R. (1983). The effects of dietary ingredient, sex and slaughter weight on cooked meat flavor profile of market lamb. Journal of Animal Science, 57(5), 1146–1153. Diario Oficial de Extremadura. (1995). Orden de 11 de enero de 1995 por la que la Consejerı´a de Agricultura y Comercio reconoce con cara´cter provisional la Denominacio´n Especı´fica ‘‘Cordero de Extremadura’’.D.O.E. de 24 de enero de 1995. European Union. (1996). Commission Regulation (EC) No. 1107/96 of 12 June 1996 on the registration of geographical indications and designations of origin under the procedure laid down in Article 17 of Council Regulation (EEC) No. 2081/92. Official Journal L 148 of 21-06-1996. European Union. (1999). Commission Regulation (EC) No. 2107/99 of 4 October 1999 supplementing the Annex to Regulation (EC) No. 2400/96 on the entry of certain names in the ‘‘Register of protected designations of origin and protected geographical indications’’ provided for in Council Regulation (EEC) No. 2081/92 on the protection of geographical indications and designations of origin for agricultural products and foodstuffs. Official Journal L 258 of 05-10-1999. Field, R. A., Williams, J. C., Ferrell, C. L., Crouse, J. D., & Kunsman, J. E. (1978). Dietary alteration of palatability and fatty acids in meat from light and heavy weight ram lambs. Journal of Animal Science, 47(4), 858–864.
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Hawkins, R. R., Kemp, J. D., Ely, D. G., Fox, J. D., Moody, W. G., & Vimini, R. J. (1985). Carcass and meat characteristics of crossbred lambs born to ewes of different genetic types and slaughtered at different weights. Livestock Production Science, 12, 241–250. Hoffman, L. C., Muller, M., Cloete, S. W. P., & Schmidt, D. (2003). Comparison of six crossbred lamb types: sensory, physical and nutritional meat quality characteristics. Meat Science, 65, 1265–1274. Hopkins, D. L., & Thompson, J. M. (2001). Inhibition of protease activity. Part 1. The effect on tenderness and indicators of proteolysis in ovine muscle. Meat Science, 59, 175–185. Jaime, I., Beltra´n, J. A., Cen˜a, P., Lo´pez-Lorenzo, P., & Roncale´s, P. (1992). Tenderisation of lamb meat: effect of rapid postmortem temperature drop on muscle conditioning and aging. Meat Science, 32, 357–366. Jeremiah, L. E., Tong, A. K. W., & Gibson, L. L. (1998). The influence of lamb chronological age, slaughter weight, and gender. Flavor and texture profiles. Food Research International, 31, 227–242. Lloyd, W. R., Slyter, A. L., & Costello, W. J. (1981). Effect of breed, sex and final weight on feedlot performance, carcass characteristics and meat palatability of lambs. Journal of Animal Science, 51(2), 316–320. Martı´nez-Cerezo, S., San˜udo, C., Panea, B., Medel, I., Delfa, R., Sierra, I., et al. (2005). Breed, slaughter weight and ageing time effects on physico-chemical characteristics of lamb meat. Meat Science, 69, 325–333. Nitz, S., Kollmannsberger, H., & Drawert, F. (1989). Determination of sensorial active trace compounds by multi-dimensional gas chromatography combined with different enrichment techniques. Journal of Chromatography A, 471, 173–185. Oliveira, I., Silva, T. J. P., Freitas, M. Q., & Paulino, F. O. (2003). Postmortem changes and tenderness of Santa Ines sheep as influenced by age. In Proceedings 49th international congress of meat science and technology. 2nd Brazilian Congress of Meat Science and Technology (pp. 197–198), 31 August–5 September 2003, Campinas, Brazil. Ouali, A. (1990). Meat tenderization: possible causes and mechanisms. A review. Journal of Muscle Foods, 1, 129–165. Paul, P. C., Torten, J., & Spurlock, G. M. (1964). Eating quality of lamb. I. Effect of age. Food Technology, 18(11), 1779–1782.
Risvik, E. (1994). Sensory properties and preferences. Meat Science, 36, 67–77. Rousset-Akrim, S., Young, O. A., & Berdague´, J. L. (1997). Diet and growth effects in panel assessment of sheepmeat odour and flavour. Meat Science, 45, 169–181. San˜udo, C., Alfonso, M., Sa´nchez, A., Berge, P., Dransfield, E., Zygoyiannis, D., et al. (2003). Meat texture of lambs from different European production systems. Australian Journal of Agricultural Research, 54, 551–560. San˜udo, C., Campo, M. M., Sierra, I., Marı´a, G. A., Olleta, J. L., & Santolaria, P. (1997). Breed effect on carcase and meat quality of suckling lambs. Meat Science, 46, 357–365. San˜udo, C., Nute, G. R., Campo, M. M., Marı´a, G., Baker, A., Sierra, I., et al. (1998b). Assessment of commercial lamb meat quality by British and Spanish taste panels. Meat Science, 48, 91–100. San˜udo, C., Sa´nchez, A., & Alfonso, M. (1998a). Small ruminant production systems and factors affecting lamb meat quality. Meat Science, 49(Suppl. 1), S29–S64. Shorthose, W. R., Powell, V. H., & Harris, P. V. (1986). Influence of electrical stimulation, cooling rates and aging on the shear force values of chilled lamb. Journal of Food Science, 51(4), 889–892, 928. Sink, J. D. (1979). Symposium on meat flavor. Factors influencing the flavor of muscle foods. Journal of Food Science, 44(1), 1–5, 11. Solomon, M. B., Kemp, J. D., Moody, W. G., Ely, D. G., & Fox, J. D. (1980). Effect of breed and slaughter weight on physical, chemical and organoleptic properties of lamb carcasses. Journal of Animal Science, 51, 1102–1107. Suarez, V. H., Busetti, M. R., Garriz, C. A., Gallinger, M. M., & Babinec, F. J. (2000). Pre-weaning growth, carcass traits and sensory evaluation of Corriedale, Corriedale · Pampinta and Pampinta lambs. Small Ruminant Research, 36, 85–89. Thompson, J. (2002). Managing meat tenderness. Meat Science, 62, 295–308. Wheeler, T. L., & Koohmaraie, M. (1994). Prerigor and postrigor changes in tenderness of ovine Longissimus muscle. Journal of Animal Science, 72, 1232–1238. Young, O. A., Berdague´, J. L., Viallon, C., Rousset-Akrim, S., & Theriez, M. (1997). Fat-borne volatiles and sheepmeat odour. Meat Science, 45, 183–200.
Breed, slaughter weight and ageing time effects on sensory characteristics of lamb S. Martı´nez-Cerezo *, C. San˜udo, I. Medel, J.L. Olleta Department of Animal Production and Food Science, University of Zaragoza, C/Miguel Servet, 177, 50013 Zaragoza, Spain Received 4 August 2004; received in revised form 10 October 2004; accepted 10 October 2004
Abstract The longissimus lumborum (right and left) from 180 entire male lambs were tasted by a nine-member trained taste panel. The samples were from lambs from three Spanish breeds; Rasa Aragonesa (local meat breed), Churra (local dairy breed) and Spanish Merino. Within breed, three slaughter live weights were considered (10–12, 20–22 or 30–32 kg) and meat was aged in a vacuum package for 1, 2, 4, 8 or 16 days. Panellists assessed a total of eight descriptors. Lamb odour and lamb flavour intensities increased with slaughter weight. However, fat flavour intensity was significantly influenced by breed, with the highest score for Rasa Aragonesa. Off-flavour intensity was influenced by breed and ageing, with higher scores for Rasa Aragonesa and longer ageing times. Tenderness and juiciness were influenced by all three effects (P 6 0.001, each) and there was a significant interaction between breed and slaughter live weight. Meat was juicier and more tender in the lightest Churra lambs, and in the Spanish Merino lambs for the heavier weight animals. Tenderness and juiciness increased with ageing. The best quality flavour was for the Spanish Merino and the intermediate and heavier lambs. 2004 Elsevier Ltd. All rights reserved. Keywords: Odour; Tenderness; Juiciness; Flavour; Taste panel
1. Introduction Meat is a complex product and, as a result, its quality evaluation is not always easy. Many studies on meat and meat products have been designed to develop instrumental or physico-chemical methods to replace the sensory test, mainly because sensory methodologies have been seen as subjective, expensive and tedious (Risvik, 1994). However, although instrumental methods have the advantages of being objective and cheaper, at the moment, they only provide partial explanations of the complex set of interactions that occur when cooked meat is smelled, chewed (Thompson, 2002) and swallowed. This partial explanation of *
Corresponding author. Tel.: +34 976761000x4148; fax: +34 976761590. E-mail address: [email protected] (S. Martı´nez-Cerezo). 0309-1740/$ - see front matter 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.meatsci.2004.10.009
instrumental analysis can be clearly observed, for example, in flavour and odour determinations. Thus, although the chemical compounds involved in odour and flavour development are relatively easy to obtain using GC–MS and GC–sniffing techniques (Nitz, Kollmannsberger, & Drawert, 1989; Young, Berdague´, Viallon, Rousset-Akrim, & Theriez, 1997), these isolated compounds do not give a global idea about the overall flavour and odour (blends of many components) and its preference by consumers. On the other hand, sensory juiciness scores are difficult to predict from instrumental measurements of meat texture or cooking losses (Thompson, 2002). During the last decades, the development of sensory and statistical methods has helped to overcome the possible subjectivity problems in sensory analyses. As a result, sensory studies are useful when a complete evaluation of meat quality has to be made.
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A great number of pre- and post-slaughter factors influence lamb meat quality (San˜udo, Sa´nchez, & Alfonso, 1998a). Among pre-slaughter factors, the influence of breed and slaughter weight on lamb sensory characteristics is unclear. In some studies, they appear to affect some organoleptic scores (Jeremiah, Tong, & Gibson, 1998; San˜udo et al., 1997), but in others they have no effect (Solomon, Kemp, Moody, Ely, & Fox, 1980; Suarez, Busetti, Garriz, Gallinger, & Babinec, 2000). Similarly, in a review by Crouse (1983), some authors found flavour differences among breeds or slaughter weights while others did not. These differences may be explained by differences in slaughter weights when breed effect was compared and because, at the same slaughter weight, breeds have different levels of maturity. Among post-slaughter factors, ageing time has been mainly associated with textural parameters (Bouton & Harris, 1972; Hopkins & Thompson, 2001; Shorthose, Powell, & Harris, 1986; Wheeler & Koohmaraie, 1994). Jaime, Beltra´n, Cen˜a, Lo´pez-Lorenzo, and Roncale´s (1992) found that increasing ageing time from 1 to 7 days made lamb meat more tender, according to a 10-member semi-trained taste panel. However, although some authors have studied the effects of ageing time on lamb, many avoid sensory analyses or include a limited number of short ageing times, although new market requirements (packaging) will lead to longer ageing times. No studies, up to date, have been performed to assess the influence of breed and slaughter weight on the evaluation of lamb meat characteristics throughout ageing. In this study, we evaluated the effect of breed and slaughter live weight (according to similar market weights for Churra, 10–12 kg; Rasa Aragonesa, 20–22 kg; and Spanish Merino, 30–32 kg) throughout ageing, considering several sensory characteristics of lamb meat assessed by a trained taste panel.
2. Materials and methods 2.1. Meat samples Samples were taken from 180 entire male lambs from three Spanish breeds: 60 Rasa Aragonesa lambs (local meat breed), 60 Churra lambs (local dairy breed) and 60 Spanish Merino lambs (specialised meat breed). Within breed, three slaughter live weights were considered: 10–12 kg (suckling lambs), 20–22 kg (light lambs) and 30–32 kg (early fattening lambs). Then, 20 lambs were analysed within each breed and slaughter weight. Each breed has an official quality label associated with a specific production system and environment that have been maintained throughout the years (including specifications about breed, feeding system, slaughter age-weight and fatness score). The European quality
label (PGI) for the Rasa Aragonesa is called Ternasco de Arago´n (European Union, 1996) and Lechazo de Castilla y Leo´n for the Churra (European Union, 1999). Cordero de Extremadura is the regional quality label for the Spanish Merino (Diario Oficial de Extremadura, 1995). The lightest lambs in each breed (unweaned) were slaughtered at the region of origin, Rasa Aragonesa lambs in Arago´n (NE Spain), Churra lambs in Castilla-Leo´n (central Spain) and Spanish Merino lambs in Extremadura (SW Spain). All the rest of the lambs were transported from those regions to the same collecting place and divided into two lots to be slaughtered at different weights. Lambs were fattened indoors with concentrate (43.3% barley, 25.0% corn, 22.3% soya-44, 4.0% acid whey, 2.1% calcium carbonate, 2.0% beet molasses, 0.5% palm oil, 0.4% mineral mix and 0.4% plain salt) and cereal straw ad libitum in the same facilities. Every week, lambs were individually weighed until they reached the target slaughter live weight. All lambs were slaughtered using standard commercial procedures, according to welfare codes of practice. Then, carcasses were suspended by the Achilles tendon and refrigerated [12 C (±2 C) for 6 h, +2 C (±2 C) for 18 h]. At 24 h post-mortem, carcasses were cut into two halves and the longissimus lumborum (without subcutaneous fat) was excised from both half carcasses (360 samples in total), wrapped in aluminium foil, vacuum-packaged into polyethylene bags, randomly aged for 1, 2, 4, 8 or 16 days at 3 C (±1 C) (samples from the same carcass were not included in the same ageing group) and were frozen at 20 C until further analysis. 2.2. Sensory evaluation A nine-member trained sensory panel was used to evaluate the samples using a quantitative descriptive analysis. Assessors were trained (ISO 8586-1:1993) in sensory profiling of lamb meat during 10 training sessions during which they developed a common vocabulary to evaluate sensory characteristics of lamb meat and agreed upon a list of descriptors and their definitions. After thawing in tap water, 2 cm-thick slices of each longissimus lumborum were cooked on a pre-heated double hot-plate grill at 200 C until the internal temperature reached 70 C. Then, they were cut into nine portions (free of visible connective tissue), which were wrapped in aluminium foil and identified with a single random three-digit code. Samples were kept warm until serving within 10 min after cooking. Sensory tests were performed, in 29 sessions, in a controlled sensory analysis laboratory (ISO 8589:1988) with individual booths, which were provided with red light to mask any differences in meat colour. In each session, panellists received sets of 3 samples representing the
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flavour quality from 1 = unpleasant to 100 = very pleasant.
three different breeds (same slaughter weight and ageing time), 3 samples representing the three different slaughter weights (same breed and ageing time) and/ or sets of 4 samples representing four out of the five different ageing times (same breed and slaughter weight), until a maximum of 13 samples per session. Meat was served following a randomised design for order and carry over effects, and panellists were asked to eat a bit of bread and to drink a bit of still water at the beginning of the sensory evaluation and between samples to try to make the palate conditions similar for each sample. Panellists evaluated the meat samples following the list of descriptors defined during the training period (Table 1). Each attribute was quantified using an unstructured line scale of 100 points. Odour was scored immediately after opening the aluminium foil parcel (1 = no odour, 100 = very intense odour). Tenderness was scored from 1 = very tough to 100 = very tender, and juiciness from 1 = very dry to 100 = very juicy. Lamb flavour, fat flavour and off-flavour were rated from 1 = no flavour to 100 = very intense flavour, and
2.3. Statistical analyses From the 360 samples, 8 replicates and 72 judgements were obtained per breed, slaughter weight and ageing time to determine the effects of breed, slaughter live weight and ageing time. Data were analysed using SPSS 8.0 for Windows. The significance of effects (breed, slaughter weight and ageing time) and their respective interactions were obtained using the General Linear Model procedures. The panellist effect was significant for all the sensory attributes (P < 0.001), as is quite common in sensory work due to the different uses of scale (Rousset-Akrim, Young, & Berdague´, 1997) and will not be considered further. Means and standard deviations were computed for every variable. The DuncanÕs multiple range test was used to show significant differences among means. Differences were considered significant at the P 6 0.05 level.
Table 1 Definition of descriptors for the quantitative descriptive sensory analyses
3. Results and discussion
Descriptor
Definition
3.1. Global results
Lamb odour intensity Off-odour intensity
Odour associated with the species Undesirable or less desirable odours in lamb meat, such as wool, stall, liver, ammonia, sulphur, rancid, etc.
Tenderness
Ease of chewing the sample between the molar teeth Global juiciness (initial + sustained) perceived during chewing
Juiciness Lamb flavour intensity Fat flavour intensity Off-flavour intensity
Flavour quality
Breed and ageing time did not have a significant influence on odour (Table 2). However, slaughter live weight modified the lamb odour intensity (P < 0.05), without having any influence on the off-odour intensity. There were no significant interactions among factors. Other studies have also failed to find a relationship between breed and odour intensity, including Crouse, Ferrell, and Cross (1983) in Suffolk and Columbia sired lambs out of Finn · Rambouillet ewes, Suarez et al. (2000) in Corriedale, Corriedale · Pampita and Pampita lambs or Hoffman, Muller, Cloete, and Schmidt (2003) using six crossbreeds.
Flavour associated with the species Flavour associated with fat Undesirable or less desirable flavours in lamb meat, such as wool, stall, liver, ammonia, sulphur, rancid, etc. Flavour preference
Table 2 F-values and significance for the sensory descriptors evaluated in the longissimus lumborum of lamb, according to the studied factors: breed (B), slaughter live weight (SLW), ageing time (A) and their interactions Descriptor
Breed
Slaughter live weight
Ageing time
B · SLW
B·A
SLW · A
B · SLW · A
Lamb odour intensity Off-odour intensity
n.s. n.s.
3.30* n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
n.s. n.s.
Tenderness Juiciness
45.66*** 45.29***
26.07*** 18.27***
72.03*** 32.22***
22.51*** 18.86***
n.s. n.s.
n.s. n.s.
n.s. n.s.
Lamb flavour intensity Fat flavour intensity Off-flavour intensity Flavour quality
n.s. 6.17** 6.19** 27.69***
16.82*** n.s. n.s. 21.94***
n.s. n.s. 7.96*** n.s.
n.s. n.s. n.s. n.s.
n.s. n.s. 3.48*** n.s.
n.s. n.s. 2.63** n.s.
n.s. n.s. n.s. n.s.
n.s., Not significant differences. * P 6 0.05. ** P 6 0.01. *** P 6 0.001.
17.6 (18.0) 19.5 (22.5) 15.5 (17.1) 16.6 (18.6) 15.2 (15.5) 14.8 (14.9) 17.2 (18.6) 15.9 (15.4) 16.5 (16.9) 17.7 (18.4) 13.6 (15.2) 14.0 (13.8) 19.1 (18.5) 17.0 (17.7) 14.6 (15.7) 16.0 (17.0) 13.6 (16.9) 15.1 (15.8) 14.8 (16.0) 15.7 (15.9) 15.5 (15.9) 15.6 (18.9) 14.7 (15.8) 13.4 (13.7) 13.8 (14.4) 15.2 (16.7) 12.7 (14.1) 16.2 (16.3) 16.6 (17.8) 16.7 (17.6) 19.7 (17.3) 18.7 (18.9) 14.7 (14.6) 14.3 (12.4) 13.7 (13.2) 14.0 (14.4) 15.1 (12.5) 17.0 (18.6) 16.1 (14.9) Off-odour intensity (1–100) RA 18.2 (18.0) CH 15.8 (16.2) ME 14.1 (16.4)
16.7 (16.8) 14.0 (14.5) 16.0 (16.9)
51.7 (19.1) 52.5 (18.3) 49.1 (20.5) 49.2 (19.3) 50.7 (18.0) 50.0 (19.6) 51.6 (18.9) 49.2 (21.0) 50.1 (19.1) 51.5 (17.2) 51.4 (18.2) 49.8 (18.5)
8 4 2 1
50.9 (16.7) 50.5 (19.9) 47.8 (18.8) 50.3 (21.1) 50.6 (18.4) 51.1 (17.0) 48.5 (21.8) 49.4 (18.0) 50.9 (19.1) 50.7 (20.1) 47.3 (18.0) 51.5 (17.4) 49.9 (20.5) 49.5 (16.2) 49.8 (17.7) 50.7 (18.4) 51.3 (15.8) 49.7 (19.0) 47.2 (20.9) 47.4 (20.6) 51.4 (20.4) 45.4 (20.2) 47.7 (20.6) 48.8 (19.4) 50.7 (20.8) 48.3 (20.2) 47.0 (18.2) Lamb odour intensity (1–100) RA 47.7 (20.9) 51.1 (18.5) CH 46.6 (18.7) 47.8 (19.9) ME 47.6 (18.8) 51.7 (17.4)
30–32 kg (Early fattening lambs)
16 8 4 2 1
20–22 kg (Light lambs)
16 8 4
In suckling lambs (Table 4), meat was more tender and juicy for Churra at any ageing time. This could be due to differences in precocity among breeds, since Churra matures earlier (lower adult live weight and dairy breed) and higher levels of fat could make the meat more tender and juicy (Hawkins et al., 1985; Paul, Torten, & Spurlock, 1964). However, at higher slaughter weights, Spanish Merino had the highest scores for both parameters. This tendency for Merino meat to be more tender was also observed by San˜udo et al. (2003) in a comparison of different European commercial lambs using trained panels from six countries.
2
3.3. Textural attributes
10–12 kg (Suckling lambs)
Lamb odour intensity (Table 3) increased with slaughter live weight in Rasa Aragonesa and Churra but not in Spanish Merino. Although, in this latter breed, lamb odour intensity increased from the suckling lambs to the light lambs, the scores from 30–32 kg lambs were similar to 10–12 kg lambs. According to DuncanÕs test there were no significant differences among the weight groups, which is similar to Field, Williams, Ferrell, Crouse, and Kunsman (1978) and Carlucci, Napolitano, Girolami, and Monteleone (1999), who did not find significant differences in odour due to slaughter weight. Although it would be expected to find higher offodour intensities at longer ageing times, all ageing times had similar and very low scores, indicating that the preservation procedure was adequate.
1
3.2. Odour attributes
Ageing (days):
PanellistsÕ scores for tenderness and juiciness were significantly affected by the three factors considered (Table 2) but, considering the F values, ageing had more effect on tenderness than breed or slaughter live weight. Breed had the most important influence on juiciness. A significant effect of the breed by slaughter weight interaction was also observed. Lamb flavour was only significantly affected (P 6 0.001) by slaughter live weight (Table 2). Even though flavour and odour are related, flavour was more affected by slaughter weight. The fat flavour intensity was only influenced by breed (P 6 0.01). There were off-flavour differences due to breed (P 6 0.01) and ageing (P 6 0.001), which could mean that the panellists detected flavour better than odour. According to Rousset-Akrim et al. (1997), proteolysis products (peptides), which are some of the many compounds involved in off-flavour, are largely water soluble and have no significant vapour pressure, so the perception of flavour is more sensitive than odour. Flavour quality was affected by breed and slaughter weight (P 6 0.001, Table 2), but not by ageing.
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S. Martı´nez-Cerezo et al. / Meat Science 69 (2005) 571–578 Table 3 Means (standard deviation) of the odour scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel
574
58.4ayr (18.2) 60.6abxs (16.7) 64.6bxyr (15.1) 59.4ayr (15.5) 57.2axrs (14.6) 62.2ayr (14.5) 58.8abyr (16.9) 55.8axrs (15.8) 61.7byr (15.9) 51.8axq (18.1) 53.4axqr (15.2) 60.6byr (12.8) a–c: Different superscripts represent significant differences among breeds (within slaughter live weight and ageing) (P 6 0.05). x–z: Different superscripts represent significant differences among slaughter live weights (within breed and ageing) (P 6 0.05). q–t: Different superscripts represent significant differences among ageing times (within slaughter live weight and breed) (P 6 0.05).
47.2axq (17.4) 48.6abxq (17.5) 53.5bxq (17.6) 56.7ayr (17.6) 60.7axr (15.7) 66.5byr (12.8) 52.5axqr (18.2) 55.8axqr (14.2) 64.2byqr (15.1) 56.4ayr (13.6) 58.4axqr (14.9) 67.2bzr (13.3) 50.4axq (15.4) 54.1axq (15.2) 62.2byqr (13.7) 46.9axq (16.6) 53.2bxq (17.9) 60.2cyq (15.3) 50.5axqr (16.5) 62.7bxr (15.0) 60.0bxs (14.0) 53.0axr (14.8) 60.3bxr (15.7) 55.3abxrs (15.9) 47.9axqr (17.2) 57.4bxqr (16.0) 47.6axq (17.2) Juiciness (1–100) RA 45.2axq (16.8) CH 53.1bxq (15.8) ME 49.4abxq (17.3)
50.1axqr (14.6) 58.4bxr (12.3) 50.6axqr (16.7)
70.0ayr (19.7) 72.4axt (17.9) 79.0bys (14.6) 69.2axr (18.1) 66.3axs (18.6) 72.1ayr (16.9) 68.4abyr (20.1) 65.4axrs (17.7) 73.1byr (17.5) 56.4axq (21.7) 59.4axqr (17.9) 71.8byr (14.2) 53.9axq (19.4) 55.3axq (19.5) 58.6axq (20.4) 73.3ayt (19.9) 73.2axs (14.6) 80.9byr (13.2) 62.6axrs (21.1) 65.0axqr (16.4) 77.5bzr (14.4) 64.7ays (17.8) 68.9axrs (18.2) 78.0byr (13.3) 56.9axqr (17.9) 60.3axyq (18.8) 71.3byq (13.3) 53.2axq (17.5) 59.1axq (20.6) 67.1byq (16.1) 59.9axr (18.4) 74.4bxs (17.1) 70.5bxs (15.6) 62.7axr (18.3) 70.9bxrs (19.6) 63.6axr (16.8) 57.8axr (15.9) 68.6bxrs (18.1) 56.1axq (19.3) 56.9axr (19.9) 66.1byr (18.6) 55.9axq (19.0)
16 8 4 2 1 16 8 4 2 1 16 8 4 2 1 Ageing (days):
Tenderness (1–100) RA 50.0axq (16.9) CH 57.0bxq (17.7) ME 53.6abxq (19.4)
30–32 kg (Early fattening lambs) 20–22 kg (Light lambs) 10–12 kg (Suckling lambs)
Table 4 Means (standard deviation) of the textural descriptor scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel
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On the other hand, the evolution of tenderness and juiciness (Table 4) varied with breed, as reported in the literature. Thus, in Rasa Aragonesa, tenderness and juiciness improved progressively as slaughter weight increased. Jeremiah et al. (1998) also observed this slaughter weight effect on overall tenderness for Canadian lambs from 31.8 to 76.8 kg. The opposite was observed in Churra lambs, where higher slaughter weights had less tender meat, as found by Lloyd, Slyter, and Costello (1981) in Targhee and Suffolk · Targhee animals at 54 and 64 kg slaughter weight, and by Oliveira, Silva, Freitas, and Paulino (2003) in Santa Ines lambs (38.83 ± 3.18 kg) and yearling muttons (52.97 ± 5.20 kg). Churra meat was also drier at higher slaughter weights. Spanish Merino meat did not adjust to any linear tendency, even though suckling lambs had lower scores for tenderness and juiciness than heavier lambs. Sensory results for tenderness were not the same as data for instrumental texture analysis from the same animals (raw meat-compression) (Martı´nez-Cerezo et al., 2005). Thus, for example, compression at 20% maximum compression was higher in the suckling lambs and increased with slaughter weight at 80% maximum compression. These discrepancies with sensory assessments could be due to differences in meat treatments, since meat for instrumental texture was raw, while meat for sensory analyses was grilled to a 70 C internal temperature, which produces a slight solubilisation of collagen and denaturation of myofibrillar proteins. There was a clear tenderisation effect produced by ageing (Table 4). Tenderness improved at longer ageing times for all the breeds and slaughter weights, with highest tenderness values at 16 days of ageing. Thus, from 1 to 16 days of ageing, the tenderness of meat samples from Rasa Aragonesa increased by almost 20%, 38% and 30%, Churra by 31%, 24% and 31% and Merino by 32%, 21% and 35% in suckling, light and early fattening lambs, respectively. Nevertheless, there were differences in tenderisation rates among breeds and slaughter live weights. In most cases tenderness at 4 days of ageing was considerably higher compared to 1 day of ageing. In six out of nine cases (three breeds · three slaughter weights), meat aged for 4 days was 65% as tender as meat aged for 16 days. Juiciness also increased with ageing, but the effect on tenderness was greater. Both textural parameters were higher at longer ageing times as a consequence of the degradation of muscle structure that reduces myofibrillar strength (Ouali, 1990) and could facilitate the release of meat juice during chewing. 3.4. Flavour attributes Flavour is one of the main characteristics in determining the acceptability of lamb meat for consumers
576 Table 5 Means (standard deviation) of the flavour scores in lamb meat (n = 180 animals) from three Spanish breeds [Rasa Aragonesa (local meat breed, RA), Churra (local dairy breed, CH) and Spanish Merino (ME)] slaughtered at three live weights and aged for different times, evaluated by a trained taste panel 10–12 kg (Suckling lambs) Ageing (days):
1
2
20–22 kg (Light lambs)
30–32 kg (Early fattening lambs)
8
16
1
2
4
8
16
1
2
4
8
16
Lamb flavour intensity (1–100) RA 54.7axqr 56.5axr (17.3) (13.4) CH 57.1axq 52.5axq (13.7) (14.3) ME 54.5axq 55.0axq (14.1) (14.7)
55.5axqr (14.0) 55.9axq (13.7) 54.0axq (14.8)
54.7axqr (12.7) 55.8axq (13.7) 53.7axq (12.9)
50.5axq (15.0) 55.6bxq (14.7) 55.7bxq (12.3)
55.7axq (13.6) 58.0axq (13.1) 56.9axq (14.3)
56.1axq (12.0) 58.0ayq (10.5) 56.3axq (12.7)
58.1axq (13.2) 56.8axq (12.1) 59.1ayq (14.8)
56.5axq (14.6) 57.3axq (13.9) 58.8ayq (15.5)
58.2ayq (12.1) 57.5axq (13.1) 59.5axq (14.3)
57.8axq (14.3) 58.2axq (15.1) 57.3axq (15.2)
56.6axq (16.8) 60.1ayq (13.3) 59.1axq (14.2)
60.0axq (15.1) 58.3axq (14.3) 59.6ayq (15.2)
58.7axq (12.8) 55.9axq (15.0) 58.2ayq (11.5)
58.2ayq (14.3) 58.2axq (14.0) 57.7axq (13.5)
Fat flavour intensity (1–100) RA 33.4axq (20.9) CH 27.8axq (20.7) ME 28.5axq (19.5)
31.1axq (19.0) 27.9axq (20.6) 29.6axq (17.6)
32.0axq (17.7) 29.8axq (18.9) 28.6axq (19.1)
30.2axq (18.3) 28.2axq (19.7) 26.7axq (17.2)
27.0axq (18.1) 25.8axq (19.5) 27.8axq (20.4)
29.1axq (16.6) 28.1axq (18.6) 26.2axq (18.3)
30.6axq (18.5) 27.2axq (19.8) 25.9axq (19.0)
29.2axq (18.2) 28.1axq (22.3) 26.0axq (19.3)
27.4axq (17.6) 30.1axq (21.8) 28.3axq (20.2)
27.5axq (18.8) 27.2axq (19.4) 27.4axq (21.1)
35.5bxr (19.3) 29.0axq (18.2) 28.2axq (19.0)
29.9axqr (20.1) 28.7axq (20.1) 27.3axq (19.2)
31.9axqr (19.7) 30.0axq (20.4) 26.8axq (19.7)
30.4axqr (19.9) 28.3axq (19.9) 28.2axq (20.2)
28.1axq (18.3) 27.2axq (19.4) 26.8axq (19.9)
Off-flavour intensity (1–100) RA 21.5axq (18.0) CH 21.0axq (18.2) ME 18.6axq (16.0)
20.7axq (16.9) 23.5axqr (19.2) 22.4axq (18.6)
18.9axq (15.9) 20.6axq (14.2) 23.5axq (21.4)
24.9axq (21.8) 20.9axq (17.3) 22.2axq (17.5)
38.5byr (23.7) 28.5axr (23.0) 24.0axq (19.1)
20.9axq (19.1) 20.0axq (16.7) 19.3axq (16.7)
20.3axq (15.6) 23.0axq (17.4) 23.1axq (18.0)
20.1axq (17.3) 21.8axq (18.0) 22.3axq (21.2)
23.2axq (19.2) 24.4axq (21.5) 25.5axq (21.2)
30.5bxr (22.3) 21.7axq (18.0) 23.8axq (20.1)
30.3byq (24.5) 21.6axq (18.7) 19.1axq (14.7)
23.0axq (19.2) 19.3axq (14.9) 22.1axq (19.3)
24.6axq (23.1) 24.5axq (17.9) 20.7axq (18.2)
24.0axq (20.8) 18.7axq (15.5) 22.9axq (18.2)
26.3axq (22.4) 25.1axq (21.1) 21.4axq (17.8)
Flavour quality (1–100) RA 48.3axr (17.0) CH 51.5axq (16.2) ME 53.1axq (15.7)
50.9axr (14.7) 51.1axq (15.7) 51.1axq (14.6)
51.8axr (13.8) 54.9axq (15.3) 51.2axq (17.0)
49.5axr (17.0) 51.5axq (16.5) 52.6axq (15.9)
41.5axq (18.8) 51.8bxq (20.9) 53.1bxq (16.7)
51.6axqr (17.0) 54.8abxq (18.0) 60.3byq (15.3)
50.8axqr (16.5) 53.3abxq (17.4) 57.4byq (17.3)
56.1abxr (14.6) 53.4axq (17.0) 60.2byq (16.8)
48.8axq (16.8) 51.5abxq (20.2) 57.3bxyq (18.9)
51.4ayqr (19.0) 57.3abxq (18.2) 60.2byq (17.4)
50.2axq (17.0) 53.7abxq (17.3) 56.5bxyq (16.0)
53.6axq (16.3) 55.2abxq (16.0) 59.9byq (16.8)
54.6axq (19.2) 53.7axq (17.7) 61.3byq (14.9)
53.5axq (18.1) 56.8axq (17.6) 58.4ayq (13.4)
53.5ayq (18.8) 55.8axq (18.3) 57.9axyq (15.8)
a,b: Different superscripts represent significant differences among breeds (within slaughter live weight and ageing) (P 6 0.05). x,y: Different superscripts represent significant differences among slaughter live weights (within breed and ageing) (P 6 0.05). q,r: Different superscripts represent significant differences among ageing times (within slaughter live weight and breed) (P 6 0.05).
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(Corcoran et al., 1999), especially in Mediterranean countries in Europe, where lighter lambs are preferred for their mild flavour. Lamb flavour was more intense for heavier lambs (Table 5). Overall values (considering all breeds and ageing times) were 54.8 ± 14.1, 57.5 ± 13.3 and 58.3 ± 14.3 for suckling, light and early fattening lambs, respectively. Jeremiah et al. (1998) also observed that lamb flavour intensity increased with age from 3–6 months to 6–9 months, but the differences were not significant. Rasa Aragonesa lambs (Table 5) had the strongest fat flavour intensity (30.19 ± 18.76, 28.22 ± 19.87, 27.48 ± 19.23, Rasa Aragonesa, Churra and Merino, respectively; considering all slaughter weights and ageing times). This is not directly related to fat quantity since, as shown in a previous paper (Martı´nez-Cerezo et al., 2005), Rasa Aragonesa only had slightly higher (not significant) intramuscular fat contents than the other breeds at 30–32 kg live weight. Therefore, breed differences in chemical composition and metabolism of lipids could probably explain this result, as reported by Sink (1979). Rasa Aragonesa (Table 5) had higher off-flavour intensity at 1 and 16 days of ageing, but breed differences within slaughter weight and ageing were not always significant. Ageing for long periods (16 days) increased off-flavour by more than 79% in the Rasa Aragonesa suckling lambs. Suckling lambs also had a stronger off-flavour at 16 days of ageing in the other studied breeds, which implies that meat from suckling lambs should not be aged as long. On the other hand, in general, at the other two slaughter weights, ageing for 4 days did not modify off-flavour intensity as much as after 16 days. As expected, Rasa Aragonesa had a slightly lower flavour quality (Table 5) since it had the highest fat flavour intensity and higher off-flavour intensity at 1 and 16 days of ageing. Spanish Merino had the highest scores. Panellists considered that light and early fattening lambs had better flavour quality than suckling lambs (Table 5). This is probably related to the background of the panellists (San˜udo et al., 1998b) because they are used to eating meat from lambs weighing between 20 and 24 kg. Since culture and previous experience have an important influence on taste preferences (Contreras, 1993), panellists probably rated with higher scores that type of lamb because they were accustomed to them and not to the characteristic milky taste of meat from suckling lambs.
4. Conclusions Breed and slaughter weight modified the sensory characteristics of lamb meat and, as a result, all meat quality labels in this species should include them in their specifications.
577
Ageing has an important effect on the sensory evaluation of lamb meat. In lambs with a slaughter weight of 10–12, 20–22 and 30–32 kg, 4 days of ageing seems to be enough to obtain high quality meat. However, ageing for longer periods (16 days) does not seem to decrease meat quality in light (20–22 kg) and early fattening (30–32 kg) lambs.
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