Influence of Anatomical Retail Cut on Physicochemical and Sensory Characteristics of Foal “Cecina”

Abstract

The effect of anatomical retail cut (knuckle, topside, and silverside) on physicochemical properties, fatty acid profile, and sensory characteristics of dry-cured foal “cecina” was studied. Almost all physicochemical properties were affected by anatomical retail cut, since the silverside presented significantly (p < 0.05) less moisture and protein content and more NaCl content than the topside and the knuckle cuts. Instrumental color parameters were also affected by piece type, having the knuckle pieces a more intense red, higher yellowness, and higher lightness compared to silverside and topside cuts. The results from the Warner-Bratzler test showed a marked difference (p < 0.001) among anatomical retail cuts, since the highest values of shear force were observed in silverside samples (9.5 versus 6.3 versus 2.3 kg/cm²; for silverside, knuckle, and topside cuts, respectively). Finally, sensorial analysis showed that dry-cured foal “cecina” manufactured from silverside was saltier, harder, and less juicy than those from the knuckle and topside cuts.

Keywords:

• Anatomical cut
• Dry-cured foal “cecina,” Fatty acid profile
• Physicochemical properties
• Sensory characteristics

INTRODUCTION

Equine meat is characterized by low fat, low cholesterol content, and high levels of Fe-heme.^[1,2] From the point-of-view of fatty acid composition, horse meat is characterized by high levels of unsaturated fatty acids (above 55%), polyunsaturated fatty acids (PUFA), predominantly the essential n-6 (linoleic acid, 18:2 n-6) and n-3 (alpha-linolenic acid [ALA] 18:3n-3) PUFA, and monounsaturated fatty acids (MUFA), primarily oleic acid (18:1n-9c).^[3] These nutritional characteristics mean that this type of meat may be considered as a good alternative to beef meat.

An increasing number of consumers are demanding meat that is authentic, tasty, rich in protein, and low in lipid and cholesterol contents. Consumers are increasingly interested in products from natural sources and lower input systems including foal meat. Modern consumers are willing to purchase new and exciting experiences and this is where meat and meat products from alternative species can feature. Similar to dry-cured hams, dry-cured foal “cecina” is produced by dry curing and drying stages, but the period of its production is shorter than that of pork hams. To manufacture dry-cured foal “cecina” it is possible the use of three different anatomical retail cuts: knuckle (quadriceps femoris composed of: vastus lateralis, vastus intermedius, vastus medialis, and rectus femoris muscles), topside (composed of semimenbranosus, adductor femoris, gracilis pectineus, and sartorious muscles), and silverside (composed of semitendinosus and biceps femoris muscles).

In general, important reductions in both moisture content and water activity take place throughout the elaboration process of dry-cured meat products.^[4] This reduction can vary depending on drying conditions, and decreased water activity may affect enzyme activity, which influences the sensorial characteristics of the final product.^[5] During the processing of this meat product, proteolysis and lipolysis constitute two of the most important mechanisms associated with the final taste of the product. These changes that take place during the ripening process of dry-cured foal “cecina” improve sensory characteristics and develop appropriate texture and flavor.^[6]

As the demand for horse meat is increasing day by day, research on dry-cured foal meat products should be conducted in order to establish the best conditions of manufacture, including the selection of the best raw materials. As far as we know, there are only two studies concerning the changes on physicochemical properties, texture, lipolysis, and volatile compounds during the manufacture of dry-cured foal “cecina.”^[6,7] There are not studies about their characteristics manufactured with other anatomical retail cuts. So, this work sets out to study the physicochemical, fatty acid profile, and sensory properties of dry-cured foal “cecina” manufactured from knuckle, topside, and silverside cuts in order to determine the characteristics and also the consumer acceptance of the three different products.

MATERIAL AND METHODS

Obtaining of Meat Cuts and Manufacture of Dry Cured Foal Cecina

For this study, 12 foals of the “Galician Mountain” breed were supplied by “Monte Cabalar,” the cooperative of breeders of the “Galician Mountain” breed (A Estrada, Pontevedra, Spain). The foals were 15 months old, and carcasses weighed around 90.4 kg. Thirty-six meat pieces (12 for each of the three cuts) with an average weight of 1.74 ± 0.23, 1.98 ± 0.22, and 2.01 ± 0.19 kg, for knuckle, silverside, and topside, respectively, were excised from the right side of the carcasses. The pieces were first rubbed with coarse salt and then placed in piles alternating layers of meat pieces and salt. Pieces were salted during 0.20 days/kg in a salting room at 2–5°C and 80–90% of relative humidity (RH). After salting, the pieces were taken from the heap, brushed, washed, and transferred to a room at 2–5ºC and 85–90% RH where they stayed for 40 days (post-salting stage). Once the post-salting stage was finished, the pieces were smoked with oak wood during 5 days in a smoke house at 12–14ºC and 65–75% RH. Finally, the pieces were dried and ripened at 14–16°C and 74–78% RH during 120 days. A total of 36 dry-cured foal “cecina” pieces (12 from each anatomical retail cut) were obtained and analyzed.

Determination of Physicochemical and Lipid Oxidation Parameters

The pH of samples was measured with the aid of a digital pH-meter (Thermo Orion 710 A+, Cambridgeshire, UK) fitted with a penetration probe. Water activity was measured using a Fast-lab (Gbx, Romans-sur-Isère Cédex, France) water activity meter device, after calibration with sodium chloride and potassium sulphate solutions. A portable colorimeter (Konica Minolta CM-600d, Osaka, Japan) with a pulsed xenon arc lamp, 0° viewing angle geometry and 8 mm aperture size, was used to estimate the color in the Commission Internationale de l’Éclairage L*a*b* (CIELAB) space: lightness, (L*); redness, (a*); yellowness, (b*). Each “cecina” piece was sliced (2.5 cm thick) and the color of the slices was measured three times. Calibration of the instrument was always performed before measurements using a white ceramic tile. Hue (h_ab) and chroma (C*) were calculated from the a* and b* values according to the formula:

The oxidation of lipids was assessed in triplicate using the 2-thiobarbituric acid method of Vyncke,^[8] with a modification consisting in an incubation of the samples at 96ºC in a forced oven (Memmert UFP 600, Schwabach, Germany). Thiobarbituric acid reactive substance (TBARs) values were calculated from a standard curve performed with 1,1,3,3-tetraethoxypropane, and expressed as mg malonaldehyde (MDA)/kg sample.

Determination of the Proximate Composition

Moisture, fat, ash and protein (Kjeldahl N × 6.25) were quantified according to the International Organization for Standardization (ISO) recommended standards 1442:1997,^[9] 1443:1973,^[10] 936:1998,^[11] and 937:1978,^[12] respectively. Total chlorides were quantified according to the Carpentier-Vohlard official method.^[13]

Warner-Bratzler (WB) and Texture Profile Analysis (TPA)

From each sample, seven pieces measuring 1 × 1 × 2.5 cm (height × width × length) were obtained in parallel to the muscle fiber direction, and next they were completely cut using a WB shear blade with a triangular slot cutting edge (1 mm thickness). Maximum shear force was determined using a texture analyzer (TA.XTplus, Stable Micro Systems, Vienna Court, UK). TPA was performed by compressing to 60% with a compression probe of 19.85 cm² of surface contact in seven meat pieces of 1 × 1 × 2.5 cm (height × width × length). The curves force-time were recorded at a crosshead speed of 3.33 mm/s; the recording speed was also 3.33 mm/s. The parameters hardness (kg), cohesiveness, springiness (mm), gumminess (kg), and chewiness (kg × mm) were obtained using the available computer software (Texture Exponent 32 [version 1.0.0.68], Stable Micro Systems, Vienna Court, UK).

Analysis of Fatty Acid Methyl Esters (FAMEs)

Intramuscular fat (IMF) was extracted from 5 g of ground meat samples, following the procedure described by Folch et al.^[14] Lipid extracts were next evaporated to dryness under vacuum at 35°C. Fifty milligrams of the extracted lipids from each sample were transesterified using a 14% (w/v) boron trifluoride solution in methanol, as described by Carreau and Dubacq^[15] and the resulting FAMEs were stored at –80°C until chromatographic analysis. Separation and quantification of FAMEs were performed following the procedures described by Bermúdez et al.^[16]

Sensorial Analysis

Sensorial evaluation of dry-cured foal “cecina” manufactured from knuckle, topside, and silverside cuts was carried out by an experienced panel (eight members) selected from the staff of the Meat Technology Centre of Galicia (Ourense, Spain). The panellists were first trained according to the methodology proposed by the ISO regulations^[17] for four months with the attributes and the scale to be used. The samples were individually labelled with three-digit random numbers. Eight sensory traits of dry-cured foal “cecina,” grouped in appearance (lean color and marbling), odor (intensity, rancidity, and cured), taste (saltiness), and texture of the lean (hardness and juiciness) were assessed according to the methodology proposed by the ISO regulations.^[18–20] The intensity of each attribute was expressed on a structured scale from 0 (very low) to 9 (very high). During sensory evaluation, the panellists were situated in private cubicles according to the ISO regulations.^[21] Water was given to the panellists to clean the palate and remove residual flavors at the beginning of the session and between samples.

Statistical Analysis

In order to evaluate the effect of the anatomical cut used for the “cecina” manufacture on each one of the parameters studied, an analysis of variance (ANOVA) using the IBM SPSS Statistics 19.0 program (IBM Corporation, Somers, NY, USA) was performed. The Duncan’s t-test was used to differentiate the least square means (LSM). All statistical tests of LSM were performed with a confidence interval of 95% (p < 0.05). Correlations between variables were established using the Pearson’s linear correlation coefficients determined with the aid of the statistical software package already cited.

RESULTS AND DISCUSSION

Effect of Anatomical Retail Cut on Physicochemical Properties of Dry-Cured Foal “Cecina”

The physicochemical properties of dry-cured foal “cecina” manufactured from knuckle, topside, and silverside cuts are summarized in Table 1. In general, almost all physicochemical properties were significantly (p < 0.05) affected by anatomical retail cut with the exception of ash content, which was similar among cuts. The pH presented significant (p < 0.001) differences among cuts, since the highest values were observed in dry-cured foal “cecina” manufactured from knuckle compared to the others. These pH values are similar to those reported in a previous study on dry-cured foal “cecina”^[6,7] and are within the range of values (5.86–5.95) found in dry-cured beef “cecina.”^[22,23] Regarding the moisture content, significant (p < 0.001) differences were also observed among pieces, and the lowest content was found in silverside samples (40.7 versus 42.7 versus 43.6% for silverside, knuckle, and topside cuts, respectively). The lower moisture percentage observed in silverside pieces could be explained by the fact that this piece has a greater surface and lesser thickness than the others, so the surface per unit of weight is greater, which favors the dehydration throughout the drying-ripening stage. This circumstance could also provoke a greater loss in water due to the exit of fluids during the salting process. This outcome is in disagreement with those reported by Molinero et al.^[24] who noticed lower moisture content in knuckle cuts from Spanish dry-cured beef “cecina.” Our mean final values were higher than those reported by Lorenzo^[6] in dry-cured foal “cecina” and by García et al.^[22] in Spanish dried beef “cecina” after 153 days of process, whereas Molinero et at.^[24] showed values of above 50% in dry-cured beef “cecina” after 360 days of processing. A similar result was found for water activity, which was lower in dry-cured foal “cecina” manufactured from silverside pieces than the other ones (0.84 versus 0.86 versus 0.86 for silverside, knuckle, and topside cuts, respectively). During the ripening process of foal “cecina,” water activity gradually declined due to the decrease of the water content, salt diffusion, and the intense dehydration that the pieces undergo during the drying-ripening stage, in fact a_w values showed a positive correlation with moisture content (r = 0.535, p < 0.01) and a negative correlation with salt content (r = –0.727, p < 0.001).

TABLE 1 Effect of anatomical retail cut on physicochemical properties of dry-cured foal “cecina.” Results expressed as means ± standard deviations (n = 12)

Attributes	Anatomical retail cut			SEM	p-Value
	Knuckle	Silverside	Topside
pH	6.11 ± 0.07^b	5.88 ± 0.06^a	5.89 ± 0.08^a	0.02	0.000
Water activity	0.86 ± 0.02^b	0.84 ± 0.02^a	0.86 ± 0.02^b	0.01	0.038
Moisture (%)	43 ± 3^b	41 ± 2^a	44 ± 2^b	0.42	0.013
Intramuscular fat (% of DM)	1.4 ± 0.3^a	2.2 ± 0.9^b	2.1 ± 0.7^b	0.14	0.039
Protein (% of DM)	82 ± 1^b	79 ± 1^a	83 ± 1^b	0.63	0.000
Ash (% of DM)	14 ± 2	15 ± 2	14 ± 2	0.31	0.116
NaCl (% of DM)	9 ± 2^a	12 ± 2^b	10 ± 1^a	0.35	0.005
TBAR’S (mg MDA/kg)	1.0 ± 0.1^a	1.5 ± 0.4^b	1.16 ± 0.09^a	0.05	0.000

^a–cMeans in the same row with different letters differ significantly (p < 0.05; Duncan test); DM: dry matter; SEM: standard error of the mean.

IMF content is one of the main factors for the quality of dry-cured meat products and the technological aptitude of raw materials for drying and maturation processes, since an adequate level of fat is determinant for the regulation of salt/water diffusion and drying processes. Statistical analysis showed that IMF was affected by anatomical retail cut, since the higher values were found in silverside and topside samples compared to knuckles pieces (Table 1). This finding is in agreement with those described by Molinero et al.^[24] who noticed higher IMF content in Spanish dried beef “cecina” manufactured from silverside cuts. The low levels of IMF reported in the present study might be attributed to the fact that foals were not fed a concentrate as finishing diet. These low contents of IMF are recommended in terms of human consumption to reduce fat intake and they are consistent with a favorable image from a dietetic point-of-view. Differences in histochemical composition between muscles might also help explain the differences found in IMF content among the retail cuts in this study. Thus, some muscles included in silverside (M. biceps femoris) and topside (M. semimenbranosus, adductor femoris, gracilis pectineus, and sartorious) cuts are characterized by a higher percentage of red fibers, with higher IMF contents than those included in knuckle (M. vastus lateralis, vastus intermedius, vastus medialis, and rectus femoris) pieces. In addition, significant differences (p < 0.001) were also described among muscles in IMF content by Lorenzo and Pateiro^[2] who reported higher IMF contents in biceps femoris and semitendinosus muscles of foals. On the other hand, protein content also presented significant (p < 0.001) differences among anatomical retail cuts, since the highest values were found in topside and knuckle samples (82.8 versus 82.5 versus 79.3% of DM for topside, knuckle, and silverside cuts, respectively). These protein contents reported in this study were higher than those found by Molinero et al.^[24] who noticed protein content below 73% of DM in Spanish dry-cured beef “cecina.”

Regarding NaCl and ash content (expressed as g/100 g of dry matter), the higher values of both parameters were obtained in dry-cured foal “cecina” manufactured from silverside pieces (Table 1). These high values can be explained by the greater surface and lesser thickness of this anatomical retail cut compared with the other pieces, which favor the penetration of salt during the salting process. These findings are in disagreement with those found by Molinero et al.^[24] who noticed high values of NaCl and ash content in cecina de León obtained from topside cuts. These NaCl and ash contents are in the range of values reported by Lorenzo^[6] in dry-cured foal “cecina” who obtained mean values of 11.9 and 16.7 g/100 g of dry matter for NaCl and ash contents, respectively. On the other hand, TBARs values also showed significant (p < 0.001) differences among anatomical retail cuts, since the higher levels were found in silverside pieces (1.5 versus 1.0 versus 1.2 mg MDA/kg; for silverside, knuckle, and topside cuts, respectively). These higher TBARs values obtained in silverside cuts are in agreement with the higher NaCl content found in this piece and could be related to the pro-oxidant action of metallic ions present as impurities in the salt used in the curing process. These values were, however, lesser than those previously noticed by Lorenzo^[2] who reported final values of 3.5 mg MDA/kg in dry-cured foal “cecina.”

Effect of Anatomical Retail Cut on Color and Textural Parameters of Dry-Cured Foal “Cecina”

In dry-cured meat products, color is one of the most outstanding characteristics of appearance and it is accepted that it could influence consumers’ choice. The influence of anatomical retail cut on colorimetric characteristics is shown in Table 2. Lightness (CIEL*-value) did not show significant (p > 0.05) differences among cuts. Regarding CIE a*-values, dry-cured foal “cecina” from knuckle cuts were more red than those from silverside or topside pieces. In other type of dry-cured products, such as dry-cured ham, redness (CIE a*-value) has been associated with the myoglobin concentration, the salt content and the formation of nitromyoglobin. In line with this, Pearson correlations indicated that CIE a*-values were negatively related to NaCl content (r = −0.372; p < 0.05).

TABLE 2 Effect of anatomical retail cut on color and textual parameters of dry-cured foal “cecina.” Results expressed as means ± standard deviations (n = 12)

	Anatomical retail cut			SEM	p-Value
	Knuckle	Silverside	Topside
Color parameters
Luminosity (L*)	27 ± 1	26.1 ± 0.9	26.4 ± 0.8	0.15	0.317
Redness (a*)	6.8 ± 0.6^b	5.6 ± 0.8^a	6.1 ± 0.4^a	0.14	0.000
Yellowness (b*)	4.7 ± 0.8^b	3.4 ± 0.6^a	3.6 ± 0.5^a	0.15	0.000
Chroma (C*)	8.4 ± 0.7^b	6.4 ± 0.9^a	7 ± 1^a	0.24	0.000
Hue (H*)	33 ± 3	32 ± 3	31 ± 3	0.57	0.333
WBSF test
Shear force (kg/cm^2)	6 ± 2^b	10 ± 2^c	2.3 ± 0.4^a	0.61	0.000
Firmness (kg/s)	1.7 ± 0.3^b	1.8 ± 0.3^b	0.47 ± 0.07^a	0.13	0.000
Total work (kg × mm)	51 ± 19^b	70 ± 11^c	24 ± 4^a	4.21	0.000
TPA trait
Hardness (kg)	11 ± 2^a	17 ± 3^b	12 ± 2^a	0.64	0.000
Springiness (mm)	0.49 ± 0.04^a	0.53 ± 0.04^b	0.55 ± 0.04^b	0.01	0.004
Chewiness (kg × mm)	3.0 ± 0.7^a	6 ± 1^b	3.3 ± 0.6^a	0.28	0.000
Gumminess (kg)	5 ± 1^a	10 ± 3^b	7 ± 2^a	0.47	0.000
Cohesiveness	0.49 ± 0.03^a	0.53 ± 0.04^b	0.54 ± 0.02^b	0.01	0.009

^a–cMeans in the same row with different letters differ significantly (p < 0.05; Duncan test); SEM: standard error of the mean.

Similarly, CIE b*-values and chroma were significantly (p < 0.001) higher in knuckle cuts than in silverside pieces, while dry-cured foal “cecina” manufactured from topside showed intermediate values. Nevertheless, no differences among anatomical retail cuts were found in hue values. Color play a determinant role in the appearance and overall acceptability of dry-cured meat products; since a defective color is rejected by consumers due to its association with a shorten ripening. Thus, the darker and less intense red color of the silverside cuts is expected to affect its acceptability among consumers who prefer dry-cured foal “cecina” with an intense red color.

The parameters obtained from the WB shear test and TPA traits are presented in Table 2. Shear force showed a marked difference (p < 0.001) among anatomical retail cuts, since the highest values were observed in silverside samples (9.5 versus 6.3 versus 2.3 kg/cm²; for silverside, knuckle, and topside cuts, respectively). These outcomes are in agreement with those found by Molinero et al.^[24] who noticed higher hydroxyproline content in silverside samples in comparison to that of the knuckle and topside cuts. Hydroxyproline content has been identified as an indicator of hardness because this parameter is related to the content of collagen, which is the major component of the connective tissue in meat. Regarding TPA traits, all parameters were significantly (p < 0.01) influenced by anatomical retail cut. Dry-cured foal “cecina” manufactured from silverside cuts exhibited higher (p < 0.001) values for hardness than those obtained from knuckle and topside samples and are in agreement with those reported previously by Molinero et al.^[24] In dry cured meat products, texture is directly related to the muscle structure, especially to the degradation of myofibrillar proteins and collagen content as well as to the IMF content and drying rate.^[25] In line with this, we found negative correlations between moisture content and shear force (r = –0.467, p < 0.01), instrumental hardness (r = –0.394, p < 0.05), gumminess (r = –0.391, p < 0.05) and chewiness (r = –0.491, p < 0.01) in the present study. On the other hand, Ramirez and Cava^[26] found a marked effect of the IMF content on instrumental texture parameters in dry-cured loin; however, in the present study, only chewiness (r = 0.570, p < 0.001) was related to IMF content.

Effect of Anatomical Retail Cut on Fatty Acid Profile of Dry-Cured Foal “Cecina”

The influence of anatomical retail cut on fatty acid composition of dry-cured foal “cecina” is presented in Table 3. Significant (p < 0.001) differences among cuts were found regarding total saturated fatty acids (SFA), while MUFA and PUFA did not show significant (p > 0.05) differences among cuts. As it can be observed in Table 3, dry-cured foal “cecina” was characterized by a lower proportion of MUFA and a higher percentage of PUFA, while the proportion of SFA varied from 34.29% in topside samples to 36.91% in knuckle cuts. These findings are in agreement with those reported for foal meat by some authors^[2,27] who noticed SFA values that ranged between 41.11 and 48.21% of total methyl esters.

TABLE 3 Effect of anatomical retail cut on fatty acid composition (% of total fatty acids) of dry-cured foal “cecina.” Results expressed as means ± standard deviations (n = 12)

Fatty acid	Anatomical retail cut			SEM	p-Value
	Knuckle	Silverside	Topside
C12:0	0.38 ± 0.07	0.37 ± 0.04	0.39 ± 0.03	0.01	0.713
C14:0	2.0 ± 0.5	2.0 ± 0.2	2.0 ± 0.4	0.07	0.985
C14:1	0.00 ± 0.00^a	0.31 ± 0.02^b	0.29 ± 0.04^b	0.03	0.000
C15:0	0.31 ± 0.04	0.4 ± 0.2	0.32 ± 0.02	0.02	0.298
C15:1	0.00 ± 0.00^a	0.14 ± 0.02^b	0.12 ± 0.01^b	0.01	0.000
C16:0	23 ± 1	22 ± 1	22 ± 1	0.22	0.228
C16:1cis-9	2.3 ± 0.6	2.1 ± 0.5	2.5 ± 0.3	0.09	0.404
C17:0	0.61 ± 0.06^b	0.54 ± 0.06^b	0.17 ± 0.05^a	0.03	0.000
C17:1cis-9	0.31 ± 0.04^a	0.39 ± 0.05^b	0.35 ± 0.05^a	0.01	0.009
C18:0	10 ± 1^b	10 ± 1^b	8.6 ± 0.2^a	0.23	0.032
C18:1cis-9	13 ± 2	12 ± 1	12.8 ± 0.4	0.28	0.211
C18:1cis-7	2.1 ± 0.3	2.0 ± 0.3	2.0 ± 0.1	0.04	0.235
C18:2n-6	23 ± 4	24 ± 3	24 ± 2	0.58	0.874
C20:0	0.16 ± 0.03^b	0.11 ± 0.02^a	0.12 ± 0.02^a	0.01	0.000
C18:3n-6	0.16 ± 0.02^a	0.19 ± 0.03^ab	0.21 ± 0.02^b	0.01	0.006
C20:1	0.27 ± 0.04^b	0.25 ± 0.04^a	0.21 ± 0.03^a	0.01	0.007
C18:3n-3	15 ± 2	15 ± 2	16 ± 1	0.32	0.668
C20:2	0.53 ± 0.07	0.50 ± 0.07	0.45 ± 0.02	0.01	0.062
C20:3n-6	0.7 ± 0.2^a	0.9 ± 0.2^b	0.85 ± 0.09^ab	0.04	0.015
C22:1n-9	0.00 ± 0.00^a	0.9 ± 0.1^b	0.00 ± 0.00^a	0.08	0.000
C20:3n-3	0.9 ± 0.1	1.0 ± 0.1	0.83 ± 0.07	0.03	0.128
C20:4n-6	3.7 ± 0.8	4 ± 1	4.0 ± 0.6	0.17	0.163
C23:0	1.0 ± 0.4^b	0.26 ± 0.04^a	0.25 ± 0.04^a	0.08	0.000
C20:5n-3	0.7 ± 0.1^a	1.3 ± 0.3^b	1.2 ± 0.1^b	0.06	0.000
C24:1	0.10 ± 0.02^b	0.07 ± 0.01^a	0.16 ± 0.02^c	0.01	0.000
C22:6n-3	0.26 ± 0.04^a	0.7 ± 0.2^b	0.63 ± 0.04^b	0.04	0.000
SFA	37 ± 2^b	35 ± 2^a	34 ± 1^a	0.35	0.001
MUFA	18 ± 3	18 ± 3	18.3 ± 0.9	0.46	0.820
PUFA	43 ± 4	46 ± 2	46 ± 3	0.67	0.064
PUFA/SFA	1.2 ± 0.1^a	1.33 ± 0.08^b	1.3 ± 0.1^b	0.03	0.008
Σn-3	16 ± 2	17 ± 1	18 ± 1	0.27	0.060
Σn-6	25 ± 6	28 ± 2	28 ± 2	0.75	0.227
n-6/n-3	1.4 ± 0.3	1.6 ± 0.2	1.46 ± 0.08	0.05	0.259
h/H	2.3 ± 0.2	2.5 ± 0.2	2.4 ± 0.2	0.04	0.189
Nutritive value	1.03 ± 0.04^b	0.98 ± 0.04^a	0.97 ± 0.04^a	0.01	0.019

^a–cMeans in the same row with different letters differ significantly (p < 0.05; Duncan test); SEM: standard error of the mean; PUFA: Σ(C18:2n – 6 + C18:3n − 6 + C18:3n – 3 + C20:2 + C20:4n – 6 + C20:3n6 + C22:6n3 + C20:3n3 + C20:5n − 3). MUFA: Σ(C14:1 + C15:1 + C16:1 + C17:1 + C18:1 + C20:1 + C22:1n – 9 + C24:1). SFA: Σ(+ C12:0 + C14:0 + C15:0 + C16:0 + C17:0 + C18:0 + C20:0 + C23:0).  Σn-6: Σ(C18:2n – 6 + C18:3n − 6 + C20:3n – 6 + C20:4n – 6). Σn-3: Σ(C18:3n – 3 + C20:3n – 3 + C20:5n − 3 + C22:6n – 3). h/H: The hypocholesterolemic/Hypercholesterolemic ratio: [(sum of C18:1n – 9, C18:1n – 7, C18:2n – 6, C18:3n – 6, C18:3n – 3, C20:3n – 6,C20:4n – 6, C20:5n – 3, C22:4n – 6, C22:5n – 3, and C22:6n – 3)/(sum of C14:0 and C16:0)].

With regard to PUFA, the main n-6 fatty acid in all pieces was C_18:2n-6. Dry-cured foal “cecina” manufactured from silverside showed the highest percentages (24.1%), although non-significant (p > 0.05) differences were observed among anatomical retail cuts. The second n-6 fatty acid was C_20:4n-6, which also did not present significant (p > 0.05) differences among samples with mean values of 4.05% of total methyl esters. The major n-3 fatty acid was C_18:3n-3, which did not show significant differences (p > 0.05) among cuts, presenting higher percentages in dry-cured foal “cecina” manufactured from topside (15.60% of total methyl esters). Forages such as grass and clover contain a high proportion of linolenic acid (50–75% of total acids) and its content in tissues is directly related to the dietary intake of the animal. The great proportion of C_18:3n-3 found in dry-cured foal “cecina” is attributed to foals having eaten only pasture until they were slaughtered. A significantly (p < 0.001) higher percentage of C_20:5n-3 was also found in topside and silverside samples than in the knuckle samples (1.17 versus 1.33 versus 0.7 %; for topside, silverside, and knuckle cuts, respectively), and thus, a higher total n-3 percentage was also found in this type of pieces. The high PUFA percentage observed in the dry-cured foal “cecina” indicates their suitability for healthier diets, and as mentioned above, human diets rich in PUFA, particularly n-3 PUFA such as ALA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), have been reported to have positive effects on health.

Within the SFA, the predominant fatty acid was palmitic acid (C_16:0), which did not show significant (p > 0.05) differences among pieces with mean values of 22.56% of total methyl esters, followed by C_18:0 and C_14:0. These outcomes were in agreement with those reported by Molinero et al.^[24] who found that palmitic acid was the most abundant one in dry-cured beef “cecina.” The SFAs, specifically myristic acid (C_14:0) and C_16:0 are typically among the most concentrated FA in meat and they have been associated with cardiovascular disease (CVD), colorectal cancer, and type 2 diabetes.^[28] Dry-cured foal “cecina” manufactured from topside and silverside cuts showed significantly (p < 0.001) lesser percentage of SFA (34.29 and 34.60%, respectively) with respect to knuckle pieces (36.91%). This is an interesting finding since nutritional guidelines recommend a lower intake of SFA and trans fatty acids (TFA) as well a higher PUFA intake (especially of n-3 family of PUFA to comply with an appropriate n-6/n-3 balance) in order to prevent CVDs.^[29] Regarding MUFA content, topside samples showed higher percentages that those from silverside and knuckle cuts, although non-significant (p > 0.05) differences were observed. Within the MUFA, the predominant fatty acid was oleic acid, showing levels around 71% of the total MUFA.

PUFA/SFA ratio (P/S) and the PUFA n-6/n-3 ratio were calculated. In relation to P/S, a value above 0.4 is recommended for healthy foods and diets^[30] although, as mentioned above, the high proportion of PUFA in and on itself is not necessarily healthy if it is not balanced in relation to the n-6/n-3 ratio, which should not exceed four^[31] or six.^[32] Excessive amounts of n-6 PUFA and very high n-6/n-3 PUFA ratios promote several kinds of pathogenesis, including CVD, cancer, and inflammatory and autoimmune diseases, whereas increased levels of n-3 PUFA (and low n-6/n-3 PUFA ratios) exert suppressive effects.^[31] In our work, silverside and topside cuts showed significantly (p < 0.01) higher P/S compared to knuckle samples (1.33 versus 1.35 versus 1.16; for silverside, topside, and knuckle cuts, respectively).

Regarding the n-6/n-3 ratio, anatomical retail cuts did not show significant (p > 0.05) differences, although dry-cured foal “cecina” manufactured from silverside pieces showed the highest ratio compared to the other ones. Ratios obtained in the three anatomical retail cuts were below the maximum levels recommended by different authors and institutions, such as the British Nutrition Foundation^[32] (n-6/n-3 ratios = 6) or Simopoulos^[31] (n-6/n-3 ratios = 4).

A better approach should use of another index, the ratio of hypocholesterolaemic/Hypercholesterolaemic (h/H) fatty acids, based on the functional effects of fatty acids on cholesterol metabolism.^[33] The percentage of fatty acids considered as hypocholesterolaemic (C_18:1cis-9, C_18:2n-6, C_18:3n-3, C_20:3n-6, and C_20:4n-6) was slightly higher in silverside and topside pieces (61%) than in knuckle cuts (59%), while the amount of hypercholesterolaemic fatty acids (C_14:0 and C_16:0) showed the opposite behavior (<24% silverside and topside pieces versus >24% in knuckle cuts; data not shown). As a result, from a healthy point of view, the h/H ratio of the dry-cured foal “cecina” manufactured from silverside was more favorable (>2.45; Table 3).

Finally, the nutritive value ([C_18:0 + C_18:1cis-9]/C_16:0), which indicates the healthiness of the diet with regard its lipid content, represents an important part of the fatty acids as a whole. Within the components of this ratio, palmitic acid (C_16:0) leds to increase blood cholesterol, while stearic acid (C_18:0) does not affect cholesterol levels and oleic acid (C_18:1cis-9) helps to decrease them. In the present study, anatomical retail cut affected this ratio (p < 0.05) that showed higher values for knuckle samples (1.03) than for silverside and topside cuts (0.98 and 0.97, respectively).

Effect of Anatomical Retail Cut on Sensory Properties of Dry-Cured Foal “Cecina”

Eight descriptors were evaluated in the sensory analysis of the dry-cured foal “cecina” (Fig. 1). Sensory panel was as effective as instrumental methods in assessing differences among anatomical retail cuts. Within appearance, lean redness scores were significantly (p < 0.01) higher in knuckle and silverside cuts compared to topside samples (6.3 versus 5.6 versus 4.8; for knuckle, silverside, and topside cuts, respectively). Discrepancies between instrumental and sensory results of lean color indicate that discrimination among anatomical retail cuts is difficult, confirming the results obtained by Molinero et al.^[24] in Spanish dry-cured beef “cecina,” who noticed that instrumental color measurement of the lean is not particularly useful to assess differences perceived by panellists (and therefore, potentially by consumers). Regarding marbling, significant differences (p < 0.01) were also observed among anatomical retail cuts, since lower marbling scores were reported for knuckle samples (3.5 versus 5.5 versus 5.1; for knuckle, silverside, and topside cuts, respectively). These findings are consistent with data reported for instrumental color determination and IMF contents. In agreement with this, Pearson correlations indicated that marbling was negatively related to CIE a*-values (r = –0.500, p < 0.01) and CIE b*-values (r = –0.615, p < 0.01), while lean redness was negatively related to IMF content (r = –0.355, p < 0.05). These outcomes agree with those previously reported by Carrapiso and García^[34] and Ramírez and Cava^[35] who also obtained in dry-cured ham a significant correlation between instrumental color measurement and marbling, and suggested that color is more influenced by fat distribution than by chemical IMF content of the muscle.

FIGURE 1 Effect of anatomical retail cut on sensory characteristics of dry-cured foal “cecina.” Plotted value for each attribute is the mean of 24 qualifications.

The odor (intensity, rancidity, and cured) traits were not significantly (p > 0.05) affected by anatomical retail cut, although the highest scores were obtained in samples from silverside pieces (Fig. 1). It was found that Pearson correlation test showed a positive relation between odor intensity and marbling (r = 0.408; p < 0.05) and which is in agreement with findings noticed by Ramirez and Cava^[35] who suggested a close relationship among IMF/marbling, aroma and odor intensity. Concerning saltiness, significant differences (p < 0.001) were also found among anatomical retail cuts, since dry-cured foal “cecina” from silverside pieces were scored saltier than the other ones (6.3 versus 4.6 versus 4.5; for silverside, knuckle, and topside cuts, respectively).

Finally, panellists observed significant differences among pieces in texture traits that are in agreement with those detected by instrumental techniques (Table 2). It was found from Pearson correlation test that hardness scores were related to total work (r = 0.499, p < 0.01), shear force (r = 0.555, p < 0.01) and TPA hardness (r = 0.514, p < 0.01), while juiciness scores were related to total work (r = –0.501, p < 0.01) and shear force (r = 0.499, p < 0.01). Panellists scored dry-cured foal “cecina” from silverside pieces harder (p < 0.001) and less juicy (p < 0.001) than those from knuckle and topside cuts (Fig. 1). These results are consistent with those reported by Ramirez and Cava^[35] who also found a positive correlation between hardness scores and WBSF.

CONCLUSIONS

The results of this study indicated that the physicochemical properties, fatty acid profile, and sensory characteristics of dry-cured foal “cecina” were affected by anatomical retail cut. Samples from silverside cut differed most with regard to its chemical composition and textural parameters, whereas the most similar cuts appeared to be topside and knuckle, both of which presented higher moisture and protein contents and lower salt levels than the silverside pieces. On the other hand, instrumental color parameters of lean indicated that knuckle pieces had a more intense red (higher CIE a*-value), higher yellowness (CIE b*-value) and higher lightness (CIE L*-value) compared to silverside and topside cuts. From a nutritional point-of-view, the three anatomical retail cuts could be considered as healthier in relation to their fatty acid profiles (low n-6/n-3 ratio and high h/H ratio), and thus they could be included regularly in the diet, although in moderation, since the fatty acid ratios are within the limit or below the current nutritional recommendation, but these products also contain a high amount of salt. Finally, sensorial analysis showed that dry-cured foal “cecina” manufactured from silverside was saltier, harder, and less juicy than those from knuckle and topside cuts.

ACKNOWLEDGMENTS

A special thanks to Monte Cabalar (A Estrada, Pontevedra) for the foal samples supplied for this research.

FUNDING

The authors are grateful to Xunta de Galicia (FEADER 2013/42) for the financial support.

Additional information

Funding

The authors are grateful to Xunta de Galicia (FEADER 2013/42) for the financial support.