Effect of ageing time on consumer preference and sensory description of foal meat

1 Effect of ageing time on consumer preference and sensory description of foal meat Lorea R. Beldarrain1, Iñaki Etaio1,2, Lara Morán1, Miguel Ángel Sentandreu3, Luis Javier R. Barron1 and Noelia Aldai1* 1Lactiker Research Group, Department of Pharmacy & Food Sciences, University of the Basque 4 Country (UPV/EHU), 01006 Vitoria-Gasteiz (Spain). 5 2Laboratorio de Análisis Sensorial Euskal Herriko Unibertsitatea (LASEHU), University of the Basque 6 Country (UPV/EHU), 01006 Vitoria-Gasteiz (Spain). 7 3Instituto de Agroquímica y Tecnología de Alimentos (CSIC), 46980 Paterna (Spain). 8 9 *Corresponding author: Noelia Aldai ([email protected]) 10 11 12 This is the accepted manuscript of the article that appeared in final form in Food Research International 129 : (2020) // Article ID 108871, which has been published in final form at https://doi.org/10.1016/j.foodres.2019.108871. © 2019 Elsevier under CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) 2 Abstract 13 A consumer test (n=120) was performed in Vitoria-Gasteiz (northern Spain) in order to study the 14 effect of ageing time (0, 7, 14 and 21 days) on the sensory quality of Hispano-Bretón foal meat. 15 Steaks (Longissimus thoracis et lumborum) were wet aged and evaluated in-mouth and visually. In 16 both cases, acceptability was scored using a hedonic scale, and sensory drivers related to ageing 17 were characterised by applying check-all-that-apply method in meat. For both, in-mouth and 18 visual acceptability, meat aged for 7 days obtained higher scores than non-aged meat, whereas 19 longer ageing periods did not improve consumer acceptability. Check-all-that-apply method 20 showed to be able to discriminate among samples, both in-mouth and visually. Results revealed 21 that texture related attributes were the most discriminant ones in the in-mouth evaluation, being 22 non-aged meat related to ‘dry‘, ‘high residue‘, ‘tough‘ and ‘chewy‘ terms, whereas aged meat was 23 associated to ‘juicy‘, ‘tender‘ and ‘easily dissolving‘ terms. Visually, consumers perceived that, 24 after 14 days of ageing, meat colour changed to ‘brownish‘. Under present study conditions, the 25 establishment of a period of 7 days of ageing would be recommended. 26 27 28 29 Keywords: horse meat, vacuum pack, consumer study, visual acceptability, in-mouth acceptability, 30 sensory drivers 31 32 3 1. Introduction 33 Horse meat is not popular in most countries mainly due to religious and/or cultural concerns 34 (Rossier, 2003; Ursin, 2016). However, it is considerably produced and consumed worldwide, 35 being Asia and America the biggest producers and Asia and Europe the most important 36 consumers, as indicated by Belaunzaran et al. (2015). This study also highlighted that horse meat 37 consumption is slowly increasing in several countries because of the availability of this interesting 38 meat source but also due to its recognized nutritional and environmental value, since horse 39 production is mainly related to grazing systems. 40 Sensory preference of meat is related to visual appearance and in-mouth perception of texture 41 and flavour (Font-i-Furnols & Guerrero, 2014). More concretely, it has been reported that 42 tenderness, juiciness and flavour are the most important sensory traits affecting meat 43 acceptability (D´Alessandro et al., 2012), being directly correlated with purchase intention and 44 willingness to pay (Banovic, Grunert, Barreira & Fontes, 2009). Thus, it is important to ensure a 45 homogeneous product quality with acceptable tenderness (Robins et al., 2003) in order to meet 46 consumer expectations. In this sense, the role of meat ageing in the improvement of meat 47 tenderness has been widely studied (Brewer & Novakofski 2008; della Malva et al., 2019; 48 Koohmaraie, 1994; Ouali et al., 2013). The level of tenderization will majorly depend on carcass 49 hanging, duration and temperature in the ageing process, together with muscle type and animal 50 species (Cassens, Arnols, Miller, Gehring & Savell, 2018; Mónson, Sañudo & Sierra, 2005; Vieira, 51 Cerdeño, Serrano, Lavín & Mantecón, 2007). 52 Meat ageing is a common practice that has been applied in the meat industry for decades (Warren 53 & Kastner, 1992). In this line, its implications on consumer acceptability have been extensively 54 studied not only in beef (Brewer & Novakofski 2008; Li et al., 2014; Monsón et al., 2005) but also 55 in pork (Chanon, D´Souza & Dunshea, 2016) and sheep meat (Font-i-Furlons et al., 2006). On the 56 contrary, few sensory studies have been focused on horse meat ageing (Gomez & Lorenzo 2012; 57 4 Lorenzo & Gomez 2012; Ruiz et al., 2020; Seong et al., 2016) and there is a clear lack of both 58 standardized ageing practices and sensory research on the field. Particularly, no consumer 59 preference studies concerning horse meat ageing have been published in the scientific literature. 60 In sensory studies, consumer tests usually focus on hedonic measurements, while sensory 61 descriptive analyses are normally performed by trained panels. The high specialization of trained 62 panels allows the collection of detailed, robust and consistent results. However, creating and 63 maintaining the panels can be quite expensive and time-consuming (Cruz et al., 2013). Thereupon, 64 consumer-based methods for sensory descriptive analyses are gaining popularity (Varela & Ares, 65 2012, Torrico et al., 2018). Among them, Check-all-that-apply (CATA) is a simple approach to 66 gather information about the sensory perception of a product and it is suggested as a valuable 67 alternative to classical descriptive methods that also captures differences among products 68 (Reinbach, Giacalone, Machado & Bredie, 2014). CATA allows the consumer to choose potential 69 terms from a given list to describe a product, with the advantage of being an easy task that may 70 give rise to more spontaneous descriptions than when intensities are rated (Dooley, Lee & 71 Meullenet, 2010). The potential of CATA method as a powerful tool for food development has also 72 been pointed (Ares et al., 2017). Actually, the combination of liking and CATA results facilitates the 73 elucidation of the sensory drivers related to the acceptability of a certain product (Ares, Barreiro, 74 Deliza, Giménez & Gámbaro, 2010). Despite the interesting approach of this sensory technique, 75 few studies have been carried out on meat or meat products (Dos Santos et al., 2015; Jorge et al., 76 2015; Popoola, Bruce, McMullen & Wismer, 2019) and, to our knowledge, this is the first time that 77 CATA is applied to investigate the effect of ageing time on consumer meat acceptability. 78 To this extent, the aim of the present study was to assess, for the first time, the visual and in-79 mouth consumer acceptability of foal meat aged over 0, 7, 14 and 21 days (d) and to study the 80 sensory drivers affected by meat ageing with CATA approach. This knowledge will contribute to 81 5 the recommendation of a certain ageing time for the horse meat industry based on consumer 82 preferences. 83 2. Material and methods 84 2.1. Animal handling 85 Ten foals (5 females and 5 males) of Hispano-Bretón breed were used for the present study. Under 86 extensive grazing conditions, foals suckled their mothers from birth (May to June 2017) until 6-8 87 months of age and then continued under the same grazing conditions until they entered a 88 commercial feedlot at 11-13 months of age. At the feedlot, foals were finished ad libitum on a 89 concentrate composed by barley, wheat bran, wheat, soybean flour, dehydrated alfalfa, corn, beet 90 pulp, soybean hulls, molasses, palm oil and salts (13.3 % protein, 2.70 % fat, 7.60 % fibre) for 100-91 120 d. Foals were cared for in accordance with Directive 2010/63/EU (2010) and were slaughtered 92 in a commercial abattoir at 15-17 months of age (August to October 2018). They were stunned 93 with a captive bolt and slaughtered and dressed according to the specifications outlined in the 94 European legislation (Council Regulation 1099/2009). The average carcass weight was of 246.2 ± 95 14.0 kg (249.9 ± 15.0 kg for females and 242.5 ± 12.5 kg for males). All carcasses were classified as 96 U (conformation) and 2 (fat cover) according to the Community scale for the classification of 97 carcasses of adult bovine animals (Council Regulation 1208/81) as there is no specific classification 98 system for meat horses at EU level. 99 2.2. Sampling 100 Two foals (female and male) were slaughtered per week during 5 consecutive weeks. After 48 101 hours (4 ºC), both right and left rib joints were removed from each carcass and transported to the 102 laboratory under refrigeration conditions. The loin, Longissimus thoracis et lumborum (LTL) 103 muscle, was subsequently excised and sliced into 1.5 cm thick steaks. From each loin, 26 steaks 104 were cut and destined for different analyses. Among them, 8 steaks beginning from the 10th rib 105 were employed for the present study. Those steaks were vacuum packed and randomly assigned 106 6 to an ageing time: 0, 7, 14 or 21 d (2 steaks per ageing day). Ageing was performed in a 107 refrigerated room (4 ± 1 ºC) without illumination. 108 When each ageing day was reached, steaks were unpacked and covered with an oxygen-109 permeable polyvinylchloride film (oxygen permeability of 580 mL/m2/h at standard pressure and 110 temperature). After 1 hour of exposure to air (4 ºC), 3 photographs of each steak (uncooked) were 111 taken under controlled artificial illumination conditions (911 ± 10 lux) using a professional digital 112 camera (Nixon-700, Nikon Corporation, Tokyo, Japan). Same white plate was used as background 113 in order to avoid differences in contrast, intensity or direction of the illumination. From the whole 114 set of photographs, 4 representative photographs were selected for each ageing time by a group 115 of experts, taking into account the variability among animals, sexes and loin sides. Same batch of 116 selected photographs were used for visual acceptability and visual CATA of all sessions. Moreover, 117 the microbial safety of foal steaks aged for 21 d was checked and it was ensured that samples met 118 the established safety requirements (TR CU 021/2011). 119 Then, all samples from each ageing time were vacuum packed and frozen at -80 ºC until the 120 consumer study. 121 2.3. Consumer study 122 2.3.1. Consumer recruitment and session organization 123 For recruitment purposes, consumer databases from the Sensory Laboratory of the University of 124 the Basque Country (LASEHU) were used. At the same time, intensive efforts were made to reach 125 potential consumers by e-mailing, posters, broadcast, social media, personal contacts, etc. 126 Interested people fulfilled out a basic recruitment questionnaire (gender, age and foal meat 127 consumption frequency). From among them, 120 volunteers from Vitoria-Gasteiz and surrounding 128 areas (northern Spain) were recruited, balancing as much as possible for age and sex. 129 Ten sessions of 12 consumers were carried out during three consecutive days in LASEHU facilities, 130 which are equipped with individual booths and computers. Sessions lasted approximately 1 hour 131 7 and were organized in the following order: in-mouth acceptability (IMA), visual acceptability (VA), 132 in-mouth CATA, visual CATA and a final questionnaire. The alternation between visual and in-133 mouth tests avoided consumer’s fatigue and provided enough time to cook the second set of 134 samples for in-mouth CATA. Data were collected using Fizz Acquisition Software Version 2.40 135 (Biosystemes, Couternon, France). 136 2.3.2. In-mouth evaluation 137 For each session, batches of 16 steaks (8 steaks per loin; one loin from a female and another loin 138 from a male foal) were used. The 8 steaks contained samples from all ageing times (0, 7, 14 or 21 139 d); 4 steaks were used for IMA and another 4 steaks were used for in-mouth CATA. All samples 140 evaluated by each consumer came from the same animal. Samples were thawed overnight (4 ºC). 141 Two hours before cooking, each set of samples (2 animals x 4 ageing times) was taken out of the 142 vacuum pack, covered with an oxygen-permeable PVC film (to avoid surface dryness) and kept at 143 room temperature. Samples were cooked in two rounds; first, the IMA set and second the in-144 mouth CATA set. All samples per set were cooked at the same time (2 steaks per grill) in 4 double 145 grills (one grill per ageing time) (Dalkyo MB-30, Sogo, Spain). Grills were set at 200 ºC and steaks 146 were cooked until they reached an internal temperature of 71 ± 1 ºC. Individual internal 147 temperature was monitored using 4-channel thermocouples (Lutron electronic, Pennsylvania, 148 USA). Cooked steaks were immediately trimmed and cut into 2 x 1.5 x 2 cm cuboids, which were 149 wrapped in aluminium foil and labelled with randomly established three-digit codes. Samples were 150 kept in heaters (heat diffusion by glass microspheres) (Indoterm, Indo, Sant Cugat, Barcelona) at 151 60-65 ºC until they were served (less than 5 minutes). 152 For IMA and in-mouth CATA, samples (one per ageing time) were provided randomly and 153 monadically. Water and unsalted crackers were available as palate cleansers between samples. 154 Tasting was performed under red light (16 ± 1 lux) in order to avoid colour bias. Acceptability 155 (IMA) was evaluated by answering the question ‘How much do you like this steak?’ in a 10 cm 156 8 continuous hedonic scale with an extra cm in both sides, ranging from ‘I extremely dislike’ to ‘I 157 extremely like’. In-mouth descriptive terms were discussed and selected by a group of experts, 158 with background in meat, from LASEHU. Previously an in-depth bibliographical search of terms 159 was performed (Maughan, Tanasawat, Conrforth, Ward & Martini, 2012; Rodbotten, Kubberod, 160 Lea & Ueland, 2004). The following 19 terms were selected: ‘cowshed‘, ‘fatty‘, ‘intense‘, ‘livery‘, 161 ‘low intensity‘, ‘rancid‘, ‘roasted‘ and ‘unpleasant‘ for odour/aroma category; ‘chewy‘, ‘dry‘, ‘easily 162 dissolving‘, ‘high residue‘, ‘juicy‘, ‘tough‘ and ‘tender‘ for texture category; and ‘bitter‘, ‘metallic‘, 163 ‘salty‘ and ‘sweet‘ for taste and trigeminal sensations category. Consumers were asked to tick off 164 all the terms that considered appropriate to describe each sample (terms from the three 165 categories were presented together and in different order along the sessions). After assessing the 166 4 samples for in-mouth CATA, consumers were asked to tick off all the attributes that relate to an 167 ‘ideal foal meat’ sample, using the same list of terms. 168 2.3.3. Visual evaluation 169 Visual acceptability and CATA were assessed by the evaluation of selected photographs for each 170 ageing period. Consumers were asked to consider the average impression of the batch of 4 171 selected photographs. In the booths, a correct position and a fixed distance to the screen were 172 established in order to avoid as much as possible differences among consumers and no 173 illumination was provided. 174 Visual CATA terms were defined beforehand and selection was performed as described for in-175 mouth CATA. Initially, the following 9 terms were selected: ‘brownish‘, ‘dark‘, ‘fresh‘, ‘maroon‘, 176 ‘not uniform colour‘, ‘pinkish‘, ‘red‘, ‘spoilt‘, ‘uniform colour‘. The questions and scale for VA were 177 the same as described for IMA, and consumers were asked to tick off all the terms that considered 178 appropriate to describe each sample. After assessing the samples of the 4 ageing times for visual 179 CATA, consumers were asked to tick off all the terms that relate to an ‘ideal foal meat’ sample. 180 2.3.4. Final questionnaire 181 9 After sensory evaluations, consumers were asked to complete a questionnaire concerning 182 demographic and socio-economic information, and their familiarity with foal and aged meat. The 183 following questions were included in the questionnaire: gender (female, male), age (18-35, 36-55, 184 >55), occupation (student, unemployed, employed, retired), how often do you consume foal 185 meat? (once a week or once a month, once a year or I have not tried), how do you purchase foal 186 meat? (steak, cut in cubes, minced, no answer), how do you prepare foal meat? (deep fried, 187 grilled, oven roasted, barbequed, stewed, no answer), do you do the shopping yourself? (yes, no), 188 have you ever tried aged meat? (yes - at restaurants, yes - at home and restaurants, no - I don’t 189 know what aged meat is), do you like aged meat? (yes, no, I have not tried/ I don’t know what 190 aged meat is). Questionnaires were available in both original languages (Spanish/Basque) of the 191 Basque region (northern Spain). 192 2.4. Statistical analysis 193 Analyses were conducted using IBM-SPSS Statistics Software Version 25.0 (SPSS Inc., IBM 194 Corporation, Armonk, USA) and XLSTAT Statistics Software Version 2011.2 (Addinsoft, Bordeaux, 195 France). 196 2.4.1. In-mouth and visual acceptability 197 The General Linear Model (GLM) of the Analysis of Variance (ANOVA) was used to determine the 198 presence or absence of significant differences (p ≤ 0.05) in the IMA and VA scores among different 199 ageing times. Normality and homoscedasticity of the variables within each group (ageing times) 200 were checked. 201 The following linear models were used: 202 For IMA scores: Yijkl= µ + ATi + ASj + (AT*AS)ij + Ck(Al(ASj)) + Al(ASj) + ƹijkl 203 For VA scores: Yijk= µ + ATi + Cj(Sk) + ƹijk 204 Models included ageing time (AT), animal sex (AS), animal (A) and session (S) as fixed factors and 205 consumer (C) as a random factor. 206 16 located close to ‘low intensity’ term while meat samples aged for 21 d, and to a lower extent meat 356 samples aged 14 d, located close to ‘intense’ and ‘roasted’ terms, being indicative of aroma 357 development over ageing time. 358 Citation frequencies of visual CATA terms are gathered in Table 5. In this case, all 9 terms initially 359 selected resulted in an effective sample size equal or over 24 (Meyners et al., 2013), and 360 statistically significant differences were observed in all of them among studied ageing times (p ≤ 361 0.001). 362 As it could be expected, meat samples aged for 21 d obtained the highest CF values for 363 undesirable terms such as ‘brownish’, ‘not uniform colour’, and ‘spoilt’, confirming that this meat 364 was not visually attractive for consumers. On the other hand, CF values of terms like ‘fresh’ and 365 ‘red’ were significantly higher in meat aged for 7 and 14 d compared to non-aged or meat aged for 366 21 d. Similarly, in beef studies, the consumer is able to discriminate the meat that is not red, as 367 they associate it with a lack of freshness (Mancini & Hunt, 2005). 368 The term ‘dark’ presented significantly higher CF values in non-aged and meat aged for 21 d 369 compared to meat aged for 7 and 14 d, and ‘maroon’ was also more cited in non-aged foal 370 samples compared to others. It seems that the consumer understood ‘dark’ as intense maroon in 371 non-aged samples and as intense brown in samples aged over 21 d. For the rest of the terms, 372 significantly higher ‘pinkish’ CF values were observed in meat aged for 14 d compared to non-aged 373 or meat aged for 21 d, while intermediate values were observed for meat aged for 7 d. Similarly, 374 higher ‘uniform colour’ CF values were observed for meat aged for 14 d compared to meat aged 375 for 21 d, while intermediate values were observed in non-aged and meat aged for 7 d. 376 As reviewed by Mancini & Hunt (2005), myoglobin is a key component of meat colour. When post 377 mortem time increases, enzyme activity and NADH pool in charge of brown metamyoglobin 378 reduction are decreased and depleted, respectively, leading to meat to discoloration going from 379 ‘red’ to ‘brownish’ and passing through ‘pinkish’ (Faustman & Cassens, 1990; McKenna et al., 380 17 2005). The time needed for the process to take place depends on both intrinsic and extrinsic 381 factors, but the results suggest that under the conditions of the present study, the change to 382 ‘brownish’ was mainly perceived by consumers after 14 d of ageing. 383 Regarding the consumer description of ideal foal meat (Table 5), ‘fresh’, ‘uniform colour’ and ‘red’ 384 were the most cited terms (96.7 %, 89.2 % and 83.3 %, respectively), while ‘not uniform colour’, 385 ‘brownish’ and ‘spoilt’ were the least desired terms (below 3.5 %). Others such as ‘maroon’, 386 ‘pinkish’ and ‘dark’ obtained intermediate CF values (20.8 %, 20.8 % and 14.2 %, respectively). 387 Correspondence Analysis was performed on the contingency table of visual CATA data, and the 388 first two dimensions explained the 97.2 % of the original inertia enabling the spatial separation of 389 samples depending on ageing time (Figure 4). As it can be noted, visual CATA terms performed a 390 good discrimination of the four ageing times. The first dimension showed the differentiation of 391 meat aged for 21 d and the rest of the meats. Meat aged for 21 d was clearly associated with 392 ‘spoilt’ and ‘brownish’ terms. The rest, and especially meat aged for 7 d and 14 d, were 393 characterized by ‘fresh’, ‘red’ and ‘uniform colour’ terms. The second dimension seemed to be 394 related to the evolution of colour where non-aged meat was related to ‘maroon’, meat aged for 7 395 d to ‘red’, meat aged for 14 d to ‘pinkish’ and meat aged for 21 d to ‘brownish’ terms. 396 4. Conclusions 397 Sensory methodologies based on consumer perception like CATA have shown to be useful to 398 characterize and discriminate foal meat aged for different time periods. For the first time, a 399 hedonic evaluation combined with a CATA characterization of aged foal meat is provided, which 400 highlights the relevance of texture attributes on the acceptability of foal meat. Moreover, it 401 evidences that changes in colour happening during the ageing process are perceived by the 402 consumer. According to these results, the best ageing time could be established at 7 days, since it 403 would be enough to obtain a good in-mouth and visual acceptability. Indeed, longer ageing 404 periods would require an economic investment that would not be translated into higher 405 18 acceptability by the consumer. Further research would be necessary in order to thoroughly 406 understand the ageing process under other conditions/factors such as breed, feeding systems, 407 muscle type and others. 408 5. Acknowlegements 409 Department of Economic Development and Infrastructures of the Basque Government is 410 acknowledged for the doctoral fellowship of L.R. Beldarrain. 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Effect of ageing time (0, 7, 14 and 21 days) on foal meat in-month and visual acceptability 564 scores depending on clusters (Agglomerative Hierarchical Clustering). 565 566 d: day; SEM: standard error of the mean. 567 Within a row, means with different superscripts indicate statistically significant differences by 568 Tukey´s test (p ≤ 0.05). 569 570 571 Table 3. Number of responses and frequencies from the questionnaire distributed according to the 572 clusters obtained from in-mouth and visual acceptability scores (Agglomerative Hierarchical 573 Clustering).574 Acceptability Cluster n 0 d 7 d 14 d 21 d SEM In-mouth 1 31 4.55 c 7.55 a 5.53 bc 6.62 ab 0.18 2 54 7.54 a 6.94 ab 7.10 ab 6.66 b 0.12 3 35 3.14 a 3.83 a 4.26 a 3.91 a 0.16 Visual 1 33 3.95 a 4.70 a 4.16 a 2.51 b 0.16 2 44 5.90 cb 6.70 ab 6.92 a 5.62 c 0.13 3 30 6.35 a 7.07 a 6.36 a 1.50 b 0.24 4 13 7.52 a 9.80 a 9.68 a 8.00 a 0.15 Acceptability Cluster n 0 d 7 d 14 d 21 d SEM In-mouth 1 31 4.55c 7.55a 5.53bc 6.62ab 0.18 2 54 7.54a 6.94ab 7.10ab 6.66b 0.12 3 35 3.14a 3.83a 4.26a 3.91a 0.16 Visual 1 33 3.95a 4.70a 4.16a 2.51b 0.16 2 44 5.90cb 6.70ab 6.92a 5.62c 0.13 3 30 6.35a 7.07a 6.36a 1.50b 0.24 4 13 7.52a 9.80a 9.68a 8.00a 0.15