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Proximate composition and physicochemical properties of European beaver (Castor fiber L.) meat
Meat Science 123 (2017) 8–12
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Proximate composition and physicochemical properties of European beaver (Castor fiber L.) meat Mariusz Florek a,⁎, Leszek Drozd b, Piotr Skałecki a, Piotr Domaradzki a, Anna Litwińczuk a, Katarzyna Tajchman b a b
Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland Department of Companion & Wildlife Animals, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland
a r t i c l e
i n f o
Article history: Received 18 December 2015 Received in revised form 15 July 2016 Accepted 23 August 2016 Available online 24 August 2016 Keywords: European beaver Meat Chemical composition Storage Technological properties
a b s t r a c t The proximate composition of meat from young and mature European beaver and physicochemical properties during storage were investigated. The young beaver meat contains 20.52 g of protein and 1.86 g of fat in 100 g, while mature animals 22.16 g and 0.73 g. Index of nutritional quality for protein ranged from 2.03 to 2.24. Storage had a greater impact on the physicochemical properties of beaver meat than animal age and muscle type. The meat of mature beavers was significantly (P b 0.05) darker (L* = 28.51) in comparison with young animals (L* = 30.79) and contained significantly (P b 0.01) more total pigments. However, the negative b* values (between − 2.05 and − 2.19) indicated a bluish tint on the surface of beaver meat. The significantly (P b 0.05) lower drip loss and cooking loss showed semimembranosus (0.65% and 17.89%) compared to longissimus thoracis et lumborum muscle (0.84% and 19.58%). Significantly (P b 0.01) lower values of TBARS, drip loss and cooking loss were determined in meat at 24 h (0.15 mg MDA kg−1, 0.59% and 15.99%) in comparison with stored for 7 days (0.46 mg MDA kg−1, 0.90% and 21.49%). Generally, storage for 7 days improved meat water holding capacity and tenderness. W-B shear force and shear energy of beaver meat decreased from 51.4 N and 0.21 J at 24 h to 33.2 N and 0.11 J at 7 days. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction The European beaver (Castor fiber Linneaus 1758) is the largest herbivorous rodent in Poland, and the carcass of an mature animal can provide over 5.5 kg of meat (Jankowska, Żmijewski, Kwiatkowska, & Korzeniowski, 2005). The population of beavers in Poland increased considerably from 24,400 individuals in 2000 to approx. 100,000 animals in 2013 (CSO, 2014). As a result of production losses in fisheries, physical destruction at aquaculture facilities and costs of implementing damage prevention methods, the growing beaver population needs to be controlled (Kloskowski, 2011). Furthermore, by reason of the considerable increase in the number of beavers in Central and Eastern Europe, as well as development of beaver farm breeding, wider consumption and sustainable hunting as a management tool for beaver population is highly demanded (Razmaitė, Šveistienė, & Švirmickas, 2011). According to regulations of the Polish Ministry of Environment from October 2014 (The Official Journal, Pos. 1348, 7.10.2014), beavers were either strictly or partially protected. However, beavers could be culled with local administrative (voivodship level) permission, e.g. in 2013 over 3500 animals were shot (CSO, 2014). Nowadays, the meat quality concept has become dynamic and includes eating and technological quality, nutritional value and safety. ⁎ Corresponding author. E-mail address: mariusz.fl[email protected] (M. Florek).
http://dx.doi.org/10.1016/j.meatsci.2016.08.008 0309-1740/© 2016 Elsevier Ltd. All rights reserved.
Thus meat diversification can be considered as an opportunity to meet the changes in consumer needs (Razmaitė et al., 2011). The nonnutritional parameters most often considered as meat quality indicators, are physicochemical and include, for example, the ultimate pH, the drip loss, the water holding capacity (WHC), the colour of meat, the cooking loss and the tenderness (Saadoun & Cabrera, 2008). A few papers have been published that evaluate the carcass quality and chemical composition of meat for both wild (Jankowska et al., 2005; Razmaitė et al., 2011; Strazdina, Sterna, Jemeljanovs, Jansons, & Ikauniece, 2015) and farmed beavers (Korzeniowski, Jankowska, Kwiatkowska, Niewęgłowski, & Żmijewski, 2001). On the other hand, very little is known about the post mortem changes of physicochemical properties or technological suitability of beaver meat. Therefore, the objective of the pilot study was to evaluate the proximate composition and technological properties of meat from young and mature European beaver during storage. 2. Materials and methods 2.1. Animals and sample preparation The research material included males of European beaver (n = 6). In Poland, beaver hunting is allowed from the first of October until the middle of March. The animals were obtained between February, 25 and March 15, 2015, by authorised hunters in two neighbouring State
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forest districts inside Lublin voivode under permission of the Regional Director for Environmental in Lublin (Ref. No. WPN.6401.32.2015.JR). The hunted animals were weighted, bled, skinned and eviscerated. The head at the atlas joint, the paws (at the wrist and tarsal joints) and the tail fin were also removed. The carcass and inner organs were examined by “trained” person upon evisceration in compliance with provisions of Regulation (EC) 853/2004 (OJ L 226, 25.6.2004, p. 22). During the examination no anomalies or hazards were identified. Eviscerated carcasses were transported to laboratory without any undue delay, in line with the highest available hygienic standards. For the purposes of this study animals lighter than 10 kg total weight were classified as “young” (up to 1 year of age) – group I (n = 3), with the remainder, weighing up to 20 kg, sexually mature males classified as “mature” (about 2–3 years) – group II (n = 3). Mean body weight of young beavers averaged 7.38 ± 1.33 kg, while mature animals 16.25 ± 3.29 kg (P b 0.05). The mean carcass weight after chilling and dressing percentage were 3782 ± 379 g and 51.66 ± 0.43% for young beavers, as well as 7930 ± 1432 g and 49.54 ± 1.21% for mature animals (both means varied significantly between groups, P b 0.05). Loins, shoulders and thighs were cut out from carcasses, then individually tightly wrapped using a 41-μm PET PVC/CPP plastic film with oxygen permeability of 8.73 cm3/(m2 × 0.1 MPa × 24 h), at 23 °C and 100% relative humidity, and then stored refrigerated in darkness at 4 °C until analysed. The analytical procedures were followed by trimming the visible adipose and connective tissue, which were then carefully separated and discarded. The entire musculus longissimus thoracis et lumborum (LTL) from loins (backbones) and the musculus semimembranosus (SM) from thighs were collected for physicochemical measurements. Muscles from left cuts were analysed 24 h post mortem, and right cuts after 7 days storage. The meat proximate composition of three cuts was determined 48 h post mortem. From left shoulder, loin and thigh the representative samples of lean muscle tissue were collected after physicochemical measurements taken 24 h post mortem conducted on LTL and SM. Duplicate measurements per sample were taken for all analysis. 2.2. Analyses Chemical compounds studied in this article: Acetone (PubChem CID: 180), Boric acid (PubChem CID: 7628), nHexane (PubChem CID: 8058), Hydrochloric acid (PubChem CID: 313), Orthophosphoric acid (PubChem CID: 1004), Sodium hydroxide (PubChem CID: 14798), Sulfuric acid (PubChem CID: 1118), Trichloroacetic acid (PubChem CID: 6421), 2-Thiobarbituric acid (PubChem CID: 1268265). 2.2.1. Proximate composition The moisture content was determined according to PN-ISO 1442:2000; total ash in compliance with PN-ISO 936:2000; crude protein content (N × 6.25) according to PN-A-04018:1975; total fat content in line with PN-ISO 1444:2000. Energy value of meat expressed as kJ 100 g−1 of fresh tissue was calculated using energy equivalents, i.e. for protein 16.76 kJ, while for fat 37.66 kJ. The index of nutritional quality (INQ) for the protein and fat was calculated using an equation specified by Hansen, Wyse, & Sorenson (1979), adopting the reference intakes for energy and selected nutrient set out in Annex XIII of Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 (OJ L 304, 22.11.2011, p. 18). 2.2.2. Total pigments Total heme pigments content was determined according to the Hornsey's (1956) method using acetone/HCl mixture. The absorbance was measured using a Varian Cary 300 Bio spectrophotometer (Varian
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Australia PTY, Ltd.) at 640 nm wavelength against a blank sample. The OD values were multiplied by 1360 (A680 × dilution factor 2) to obtain total pigments as ppm of haematin. 2.2.3. 2-Thiobarbituric acid (TBA) measurements Lipid oxidation was determined measuring 2-thiobarbituric acid reactive substances (TBARS) according to the method of Witte, Krause, & Bailey (1970). The resulting colour was measured at 530 nm in Varian Cary 300 Bio spectrophotometer (Varian Australia PTY, Ltd.). The TBARS values were calculated by multiplying absorbance by 5.2. Results were expressed as mg of malondialdehyde (MDA) per kg of tissue. 2.2.4. pH measurement The meat pH was measured using CP-401 pH-meter (Elmetron, Poland) directly in muscle tissue at 24 h (ultimate pH), and 7 days (after storage) post mortem. 2.2.5. Colour measurements The meat colour was measured using Minolta CR-310 (Minolta Camera Co., Ltd., Osaka, Japan) portable chromameter (illuminant D65, geometry 0° and 50 mm of measure aperture). Due to diameter of aperture colour measurement was determined only for semimembranosus muscle. The entire muscle had been removed from thigh, then cut off to create a fresh surface and bloomed for 30 min at 4 °C. Results were given in the CIE L*a*b* colour space (CIE, 2004). 2.2.6. Drip and cooking loss Drip and cooking loss were determined according to Honikel (1998). Drip loss (DL) was expressed as a percentage of the initial weight of muscle sample to samples after storage. Cooking loss (CL) was expressed as a percentage of the initial weight of muscle sample to samples after thermal treatment in the water bath at 70 °C for 45 min, then cooled for 30 min in running tap water and stored at 4 °C until analysis. 2.2.7. Expressible water and meat spreadability The filter paper press method (Grau & Hamm, 1952) was used to measure the meat spreadability and the amount of expressible water from meat (0.3 g) held under pressure (2-kg pressure for 5 min). The total and meat area were measured using imaging software (MultiScan Base ver. 14). The area of the outer circle represented the expressible water while the inner circle represented meat spreadability. 2.2.8. Warner-Bratzler shear force Shear force (N) and shear energy (J) measurement was carried out using Zwick/Roell universal testing machine Proline BDO125 FB0.5TS (Zwick GmbH & Co, Ulm, Germany) and Warner-Bratzler device (Vblade), after thermal treatment of the samples. From each muscle sample a minimum of five stripes (10 × 10 × 50 mm) of 1 cm2 area were cut perpendicular to the fiber direction, at a crosshead speed of 100 mm min−1. Results of measurements were obtained using TestXpert® II software. 2.3. Statistical analysis The analyses were performed using the Statistica 12 software (StatSoft, 2014). For proximate composition to compare the means for three cuts (six samples of each cut) obtained from young and mature beavers, the analysis of variance (ANOVA) was performed using the General Linear Model (GLM). The linear model included fixed effects of carcass cut and animal age (young and mature) with interaction. Similarly, the main effects of animal age (young and mature), muscle type (LTL and SM) and storage post mortem (24 h and 7 days) and their interactions on physicochemical properties of beaver meat were analysed using the GLM procedure. Considering the lack of interactions for proximate composition of meat and physicochemical properties of muscles only the main effects were reported. Statistical significance was set at P b 0.05 or P b 0.01.
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3. Results and discussion 3.1. Proximate composition The meat proximate composition and indices were given in Table 1. No differences (P N 0.05) in all constituents and indices were observed between beaver cuts. The meat from all cuts had a relatively high protein (between 20.88% and 21.45%) and low (between 0.96% and 1.95%) fat contents. Consequently, the energy value of meat regardless of cut was similar, ranged from 396 kJ 100 g−1 (loin) to 423 kJ 100 g−1 (shoulder). The meat from mature beavers contained significantly more protein (P b 0.01), but less fat and moisture (P b 0.01 and P b 0.05). Consequently, the significantly lower (P b 0.01) moisture:protein ratio and INQ for fat, but higher INQ for protein were found in meat from mature animals. A similar (P N 0.05) content of ash and energy value was determined in meat regardless animal age. The present study revealed that meat both young and mature beavers is a good source of protein, due to high values of INQ (2.03–2.24). In the present research protein and ash contents were close to those reported by Korzeniowski, Żmijewski, Jankowska, & Kwiatkowska (2002b) for meat (loin, thigh and tail mixture) of farmed beavers (22.09 and 1.33 g 100 g−1), and by Jankowska et al. (2005) for wild beavers (20.9–21.8% and 1.27–1.31%). Similar content of protein and ash to present results was also stated by Razmaitė et al. (2011) in thigh of wild beavers hunted in Lithuania (21.6 and 1.09%), and Strazdina et al. (2015) for biceps femoris of animals from Latvia (21.39 and 1.13%). In other investigation Korzeniowski, Kwiatkowska, Jankowska, & Żmijewski (2002a) did not find any influence of beaver weight (b10 kg, 10–20 kg, N20 kg) and sex (male vs. female) on the chemical composition of meat. Similarly, Tulley et al. (2000) found no differences in protein and moisture content when comparing male vs. female and young vs. old nutria caught in the wild. The fat content in present study was higher compared to Lithuanian research (0.51%) (Razmaitė et al., 2011), but lower than Latvian (4.29%) (Strazdina et al., 2015), and earlier Polish (3.8–4.6%) (Jankowska et al., 2005; Korzeniowski, Kwiatkowska, et al., 2002a) investigations. Although, no additional information about age or weight of beavers from Lithuania and Latvia were reported, it is well known that the lipids content in different tissues depends on the composition of diet and dietary habits of beavers (Czyżowski, Karpiński, & Drozd, 2009), as well as season (Razmaitė et al., 2011). The high content of fat in muscle tissue from young beavers may be related, among other factors, to the initial feeding stage, i.e. suckling period. The beaver weight at birth ranges between 320 and 770 g. In the age of 15 days this weight is already doubled, and during lactation (for approximately 60 days) the beavers reach the mean weight of 3.1 (2.0–4.8) kg. Rapid growth of kits is possible owing to high nutritive value of beaver females' milk, which is characterized by a high dry matter (in the range of 21.6 to 30%), fat
(8.2–17.6%) and total protein (8.0–10.0%) contents (Żurowski, Kisza, & Kruk, 1971). In present study no differences in energy value were found between cuts and beaver age. Higher energy compared to our results was reported by Korzeniowski, Kwiatkowska, et al. (2002a) for thigh and rump (492 and 516 kJ/100 g, respectively) from wild beaver males hunted in autumn. However, these differences might be explained by a higher fat content (thigh 3.5% and rump 4.1%) related to hunting season and the availability of the food resources. 3.2. Physicochemical properties Table 2 shows the effect of animal age, muscle type and storage on physicochemical properties of beaver meat. The meat of mature animals contained significantly (P b 0.05) more total pigments and showed significantly (P b 0.05) darker surface compared to young animals. Muscle type significantly influenced drip and cooking loss (P b 0.05) as well total pigments content (P b 0.01). Lower values of drip and cooking loss, but higher content of pigments showed SM than LTL. However, the significant impact of storage was observed for the most physicochemical properties, with the exception of pH and CIE colour characteristics. The TBARS value at 24 h was not very high, but significantly (P b 0.01) increased, even triplet initial level after 7 days post mortem. Nevertheless, this value was well below those threshold levels indicating rancidity or warmed-over flavour in pork - approximately 1.0 mg of MDA per kg tissue (Gray & Pearson, 1987) or in beef - 2.0 mg (Campo et al., 2006). The storage significantly (P b 0.01) increased drip and cooking loss after 7 days, compared to amounts at 24 h post mortem. Nevertheless, storage improved significantly meat tenderness (P b 0.01) and water holding capacity (P b 0.05). The studies on the technological parameters of meat obtained from large rodents are rarely published. However, some information for capybara was available in the literature. Bressan et al. (2004) reported similar pH (6.02) and shear force (50.9 N), but almost twice higher cooking loss (31.28%) in males longissimus dorsi after 24 h post mortem, compared to our results. In present study CIE L*, a* and b* values were determined only for SM muscle up to 7 days post mortem (Table 2); in the future it will be important to follow changes during longer storage for different muscles. Among colour coordinates, significant (P b 0.05) difference was stated only for lightness (L*). The SM muscle of mature beavers was darker (L* = 28.51) in comparison to meat of young animals (L* = 30.97). The dark colour of meat of mature beavers resulted from the significantly (P b 0.01) higher total pigment concentrations in comparison with young animals. Beaver muscles store large quantities of oxygen which results from the specific environmental conditions under which they live. In present study it was reflected by a high total pigment concentrations in LTL and SM which were greater than found in bovine meat, for
Table 1 Effect of carcass cut and animal age on proximate composition of beaver meat (mean ± standard deviation). Components and indices
Moisture (g 100 g−1) Protein (g 100 g−1) Fat (g 100 g−1) Ash (g 100 g−1) Moisture:protein ratio Energy (kJ 100 g−1) INQ for protein INQ for fat
Carcass cut (C)
Animal age (A)
P values
Loin n=6
Thigh n=6
Shoulder n=6
Young beaver (up to 1 year) n=9
Mature beaver (2–3 years) n=9
C
A
76.38 ± 0.63 21.45 ± 0.93 0.96 ± 0.51 1.16 ± 0.12 3.57 ± 0.18 396 ± 11.7 2.17 ± 0.11 0.07 ± 0.03
76.19 ± 0.61 21.36 ± 0.82 1.22 ± 0.68 1.19 ± 0.05 3.57 ± 0.16 404 ± 18.7 2.12 ± 0.14 0.09 ± 0.04
76.13 ± 0.57 20.88 ± 1.52 1.95 ± 0.75 1.19 ± 0.04 3.66 ± 0.29 423 ± 25.9 1.99 ± 0.26 0.13 ± 0.08
76.56b ± 0.51 20.52A ± 0.84 1.86B ± 0.81 1.19 ± 0.08 3.74B ± 0.17 414 ± 18.6 2.03A ± 0.14 0.13B ± 0.04
75.80a ± 0.38 22.16B ± 0.30 0.73A ± 0.19 1.18 ± 0.08 3.42A ± 0.10 399 ± 10.6 2.24B ± 0.08 0.05A ± 0.02
NS NS NS NS NS NS NS NS
⁎ ⁎⁎ ⁎⁎
INQ, index of nutritional quality. NS, not significant. Means in the same row with different letters are significantly different: a, b P b 0.05; A, B P b 0.01. ⁎ P b 0.05. ⁎⁎ P b 0.01.
NS ⁎⁎ NS ⁎⁎ ⁎⁎
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Table 2 Effect of animal age, muscle and storage on physicochemical properties of beaver meat (mean ± standard deviation). Characteristics
pH TBARS (mg MDA kg−1) Drip loss (%) Cooking loss (%) Expressible water (%) Spreadability (%) Shear force (N) Shear energy (J) Total pigments (ppm) CIE L* CIE a* CIE b*
Animal age (A)
Muscle (M)
Storage (S)
P values
Young beaver (up to 1 year) n = 12
Mature beaver (2–3 years) n = 12
LTL n = 12
SM n = 12
24 h n = 12
7 days n = 12
A
M
S
5.96 ± 0.13 0.31 ± 0.19 0.72 ± 0.28 18.42 ± 3.14 55.63 ± 5.22 44.36 ± 5.22 38.0 ± 10.6 0.14 ± 0.06 359A ± 56.3 30.97b ± 1.10 19.80 ± 0.94 −2.05 ± 0.50
6.09 ± 0.15 0.31 ± 0.20 0.79 ± 0.21 19.21 ± 3.59 53.93 ± 4.50 46.07 ± 4.50 48.7 ± 12.3 0.19 ± 0.09 608B ± 114.2 28.51a ± 1.04 18.73 ± 1.11 −2.19 ± 0.40
5.99 ± 0.17 0.26 ± 0.14 0.84b ± 0.29 19.58b ± 3.29 55.78 ± 4.13 44.21 ± 4.13 45.5 ± 12.1 0.17 ± 0.09 401A ± 111.5 – – –
6.06 ± 0.13 0.36 ± 0.23 0.65a ± 0.17 17.89a ± 3.16 54.13 ± 5.66 45.87 ± 5.66 40.1 ± 10.9 0.15 ± 0.06 517B ± 173.0 29.74 ± 1.41 19.27 ± 1.05 −2.12 ± 0.42
5.98 ± 0.14 0.15A ± 0.04 0.59A ± 0.11 15.99A ± 1.67 57.45b ± 4.03 42.55b ± 4.03 51.4B ± 11.4 0.21B ± 0.08 – 29.22 ± 1.64 19.59 ± 0.81 −1.96 ± 0.41
6.10 ± 0.14 0.46B ± 0.16 0.90B ± 0.26 21.49B ± 2.05 52.45a ± 4.52 47.55a ± 4.52 33.2A ± 6.0 0.11A ± 0.03 – 30.26 ± 1.53 19.69 ± 0.89 −2.28 ± 0.42
NS NS NS NS NS NS NS NS ⁎⁎ ⁎
NS NS ⁎ ⁎
NS ⁎⁎ ⁎⁎ ⁎⁎ ⁎ ⁎ ⁎⁎ ⁎⁎
NS NS
NS NS NS NS ⁎⁎ – – –
– NS NS NS
LTL, longissimus thoracis et lumborum; SM, semimembranosus; TBARS, 2-thiobarbituric acid reactive substances. CIE L* = black to white (0 to 100); CIE a* = negative green, positive red; CIE b* = negative blue, positive yellow. NS, not significant. Means in the same row with different letters are significantly different: a, b P b 0.05; A, B P b 0.01. ⁎ P b 0.05. ⁎⁎ P b 0.01.
instance veal (Florek, Litwińczuk, Skałecki & Grodzicki, 2009), beef (Litwińczuk et al., 2014) or buffalo meat (Malik & Sharma, 2010). There were no significant effects of beaver age or storage on a* and b* coordinates. However, the negative value of the b* indicated a bluish tint on the beaver SM surface after blooming. The higher values for L* and positive b*, whereas lower for a* (35.02, 1.85 and 9.88, respectively) compared to those in present trial were reported by Bressan et al. (2004) for longissimus dorsi of capybara males. Generally, taking into account the physicochemical properties, presented comparisons indicate that differences between beaver ages or muscle type were lesser than the differences between storage. Our findings point to an improvement of water holding capacity (reduction in expressible water and a low drip loss) and tenderness (reduction in shear force and shear energy) of beaver meat with 7 days storage. The shear force of beaver meat averaged 33.2 N after 7 days storage should be considered very tender (Belew, Brooks, Mckenna, & Savell, 2003). 4. Conclusions This pilot study showed that beaver meat is a rich and good source of protein, due to high value of nutritional quality index (INQ) as well as has a relatively low fat content. Additionally, colour of beaver meat is influenced by the total pigment concentrations, which increases with age. Results suggest that storage has a larger impact on technological properties and lipid oxidation (TBARS) compared to beaver age or muscle type. Furthermore, the tendency of tenderness improvement and water holding capacity after 7 days storage was revealed. Summing up, the future investigations are needed to understand presented observation, as well as widen the knowledge of this alternative red meat. Author contributions Designed the study: LD MF. Organized sample collection: LD KT. Performed the technological measurements: MF PS PD. Performed the chemical analysis: PD AL. Helped in data acquisition: KT. Analysed the data: MF PS PD. Performed the statistical analysis, drafted the manuscript and decided the submission of the article for publication: MF. Involved in the discussion of the manuscript: LD PS PD KT AL. All authors have read and approved the manuscript to be published. Conflict of interests There is no conflict of interest.
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Proximate composition and physicochemical properties of European beaver (Castor fiber L.) meat Mariusz Florek a,⁎, Leszek Drozd b, Piotr Skałecki a, Piotr Domaradzki a, Anna Litwińczuk a, Katarzyna Tajchman b a b
Department of Commodity Science and Processing of Raw Animal Materials, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland Department of Companion & Wildlife Animals, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland
a r t i c l e
i n f o
Article history: Received 18 December 2015 Received in revised form 15 July 2016 Accepted 23 August 2016 Available online 24 August 2016 Keywords: European beaver Meat Chemical composition Storage Technological properties
a b s t r a c t The proximate composition of meat from young and mature European beaver and physicochemical properties during storage were investigated. The young beaver meat contains 20.52 g of protein and 1.86 g of fat in 100 g, while mature animals 22.16 g and 0.73 g. Index of nutritional quality for protein ranged from 2.03 to 2.24. Storage had a greater impact on the physicochemical properties of beaver meat than animal age and muscle type. The meat of mature beavers was significantly (P b 0.05) darker (L* = 28.51) in comparison with young animals (L* = 30.79) and contained significantly (P b 0.01) more total pigments. However, the negative b* values (between − 2.05 and − 2.19) indicated a bluish tint on the surface of beaver meat. The significantly (P b 0.05) lower drip loss and cooking loss showed semimembranosus (0.65% and 17.89%) compared to longissimus thoracis et lumborum muscle (0.84% and 19.58%). Significantly (P b 0.01) lower values of TBARS, drip loss and cooking loss were determined in meat at 24 h (0.15 mg MDA kg−1, 0.59% and 15.99%) in comparison with stored for 7 days (0.46 mg MDA kg−1, 0.90% and 21.49%). Generally, storage for 7 days improved meat water holding capacity and tenderness. W-B shear force and shear energy of beaver meat decreased from 51.4 N and 0.21 J at 24 h to 33.2 N and 0.11 J at 7 days. © 2016 Elsevier Ltd. All rights reserved.
1. Introduction The European beaver (Castor fiber Linneaus 1758) is the largest herbivorous rodent in Poland, and the carcass of an mature animal can provide over 5.5 kg of meat (Jankowska, Żmijewski, Kwiatkowska, & Korzeniowski, 2005). The population of beavers in Poland increased considerably from 24,400 individuals in 2000 to approx. 100,000 animals in 2013 (CSO, 2014). As a result of production losses in fisheries, physical destruction at aquaculture facilities and costs of implementing damage prevention methods, the growing beaver population needs to be controlled (Kloskowski, 2011). Furthermore, by reason of the considerable increase in the number of beavers in Central and Eastern Europe, as well as development of beaver farm breeding, wider consumption and sustainable hunting as a management tool for beaver population is highly demanded (Razmaitė, Šveistienė, & Švirmickas, 2011). According to regulations of the Polish Ministry of Environment from October 2014 (The Official Journal, Pos. 1348, 7.10.2014), beavers were either strictly or partially protected. However, beavers could be culled with local administrative (voivodship level) permission, e.g. in 2013 over 3500 animals were shot (CSO, 2014). Nowadays, the meat quality concept has become dynamic and includes eating and technological quality, nutritional value and safety. ⁎ Corresponding author. E-mail address: mariusz.fl[email protected] (M. Florek).
http://dx.doi.org/10.1016/j.meatsci.2016.08.008 0309-1740/© 2016 Elsevier Ltd. All rights reserved.
Thus meat diversification can be considered as an opportunity to meet the changes in consumer needs (Razmaitė et al., 2011). The nonnutritional parameters most often considered as meat quality indicators, are physicochemical and include, for example, the ultimate pH, the drip loss, the water holding capacity (WHC), the colour of meat, the cooking loss and the tenderness (Saadoun & Cabrera, 2008). A few papers have been published that evaluate the carcass quality and chemical composition of meat for both wild (Jankowska et al., 2005; Razmaitė et al., 2011; Strazdina, Sterna, Jemeljanovs, Jansons, & Ikauniece, 2015) and farmed beavers (Korzeniowski, Jankowska, Kwiatkowska, Niewęgłowski, & Żmijewski, 2001). On the other hand, very little is known about the post mortem changes of physicochemical properties or technological suitability of beaver meat. Therefore, the objective of the pilot study was to evaluate the proximate composition and technological properties of meat from young and mature European beaver during storage. 2. Materials and methods 2.1. Animals and sample preparation The research material included males of European beaver (n = 6). In Poland, beaver hunting is allowed from the first of October until the middle of March. The animals were obtained between February, 25 and March 15, 2015, by authorised hunters in two neighbouring State
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forest districts inside Lublin voivode under permission of the Regional Director for Environmental in Lublin (Ref. No. WPN.6401.32.2015.JR). The hunted animals were weighted, bled, skinned and eviscerated. The head at the atlas joint, the paws (at the wrist and tarsal joints) and the tail fin were also removed. The carcass and inner organs were examined by “trained” person upon evisceration in compliance with provisions of Regulation (EC) 853/2004 (OJ L 226, 25.6.2004, p. 22). During the examination no anomalies or hazards were identified. Eviscerated carcasses were transported to laboratory without any undue delay, in line with the highest available hygienic standards. For the purposes of this study animals lighter than 10 kg total weight were classified as “young” (up to 1 year of age) – group I (n = 3), with the remainder, weighing up to 20 kg, sexually mature males classified as “mature” (about 2–3 years) – group II (n = 3). Mean body weight of young beavers averaged 7.38 ± 1.33 kg, while mature animals 16.25 ± 3.29 kg (P b 0.05). The mean carcass weight after chilling and dressing percentage were 3782 ± 379 g and 51.66 ± 0.43% for young beavers, as well as 7930 ± 1432 g and 49.54 ± 1.21% for mature animals (both means varied significantly between groups, P b 0.05). Loins, shoulders and thighs were cut out from carcasses, then individually tightly wrapped using a 41-μm PET PVC/CPP plastic film with oxygen permeability of 8.73 cm3/(m2 × 0.1 MPa × 24 h), at 23 °C and 100% relative humidity, and then stored refrigerated in darkness at 4 °C until analysed. The analytical procedures were followed by trimming the visible adipose and connective tissue, which were then carefully separated and discarded. The entire musculus longissimus thoracis et lumborum (LTL) from loins (backbones) and the musculus semimembranosus (SM) from thighs were collected for physicochemical measurements. Muscles from left cuts were analysed 24 h post mortem, and right cuts after 7 days storage. The meat proximate composition of three cuts was determined 48 h post mortem. From left shoulder, loin and thigh the representative samples of lean muscle tissue were collected after physicochemical measurements taken 24 h post mortem conducted on LTL and SM. Duplicate measurements per sample were taken for all analysis. 2.2. Analyses Chemical compounds studied in this article: Acetone (PubChem CID: 180), Boric acid (PubChem CID: 7628), nHexane (PubChem CID: 8058), Hydrochloric acid (PubChem CID: 313), Orthophosphoric acid (PubChem CID: 1004), Sodium hydroxide (PubChem CID: 14798), Sulfuric acid (PubChem CID: 1118), Trichloroacetic acid (PubChem CID: 6421), 2-Thiobarbituric acid (PubChem CID: 1268265). 2.2.1. Proximate composition The moisture content was determined according to PN-ISO 1442:2000; total ash in compliance with PN-ISO 936:2000; crude protein content (N × 6.25) according to PN-A-04018:1975; total fat content in line with PN-ISO 1444:2000. Energy value of meat expressed as kJ 100 g−1 of fresh tissue was calculated using energy equivalents, i.e. for protein 16.76 kJ, while for fat 37.66 kJ. The index of nutritional quality (INQ) for the protein and fat was calculated using an equation specified by Hansen, Wyse, & Sorenson (1979), adopting the reference intakes for energy and selected nutrient set out in Annex XIII of Regulation (EU) No 1169/2011 of the European Parliament and of the Council of 25 October 2011 (OJ L 304, 22.11.2011, p. 18). 2.2.2. Total pigments Total heme pigments content was determined according to the Hornsey's (1956) method using acetone/HCl mixture. The absorbance was measured using a Varian Cary 300 Bio spectrophotometer (Varian
9
Australia PTY, Ltd.) at 640 nm wavelength against a blank sample. The OD values were multiplied by 1360 (A680 × dilution factor 2) to obtain total pigments as ppm of haematin. 2.2.3. 2-Thiobarbituric acid (TBA) measurements Lipid oxidation was determined measuring 2-thiobarbituric acid reactive substances (TBARS) according to the method of Witte, Krause, & Bailey (1970). The resulting colour was measured at 530 nm in Varian Cary 300 Bio spectrophotometer (Varian Australia PTY, Ltd.). The TBARS values were calculated by multiplying absorbance by 5.2. Results were expressed as mg of malondialdehyde (MDA) per kg of tissue. 2.2.4. pH measurement The meat pH was measured using CP-401 pH-meter (Elmetron, Poland) directly in muscle tissue at 24 h (ultimate pH), and 7 days (after storage) post mortem. 2.2.5. Colour measurements The meat colour was measured using Minolta CR-310 (Minolta Camera Co., Ltd., Osaka, Japan) portable chromameter (illuminant D65, geometry 0° and 50 mm of measure aperture). Due to diameter of aperture colour measurement was determined only for semimembranosus muscle. The entire muscle had been removed from thigh, then cut off to create a fresh surface and bloomed for 30 min at 4 °C. Results were given in the CIE L*a*b* colour space (CIE, 2004). 2.2.6. Drip and cooking loss Drip and cooking loss were determined according to Honikel (1998). Drip loss (DL) was expressed as a percentage of the initial weight of muscle sample to samples after storage. Cooking loss (CL) was expressed as a percentage of the initial weight of muscle sample to samples after thermal treatment in the water bath at 70 °C for 45 min, then cooled for 30 min in running tap water and stored at 4 °C until analysis. 2.2.7. Expressible water and meat spreadability The filter paper press method (Grau & Hamm, 1952) was used to measure the meat spreadability and the amount of expressible water from meat (0.3 g) held under pressure (2-kg pressure for 5 min). The total and meat area were measured using imaging software (MultiScan Base ver. 14). The area of the outer circle represented the expressible water while the inner circle represented meat spreadability. 2.2.8. Warner-Bratzler shear force Shear force (N) and shear energy (J) measurement was carried out using Zwick/Roell universal testing machine Proline BDO125 FB0.5TS (Zwick GmbH & Co, Ulm, Germany) and Warner-Bratzler device (Vblade), after thermal treatment of the samples. From each muscle sample a minimum of five stripes (10 × 10 × 50 mm) of 1 cm2 area were cut perpendicular to the fiber direction, at a crosshead speed of 100 mm min−1. Results of measurements were obtained using TestXpert® II software. 2.3. Statistical analysis The analyses were performed using the Statistica 12 software (StatSoft, 2014). For proximate composition to compare the means for three cuts (six samples of each cut) obtained from young and mature beavers, the analysis of variance (ANOVA) was performed using the General Linear Model (GLM). The linear model included fixed effects of carcass cut and animal age (young and mature) with interaction. Similarly, the main effects of animal age (young and mature), muscle type (LTL and SM) and storage post mortem (24 h and 7 days) and their interactions on physicochemical properties of beaver meat were analysed using the GLM procedure. Considering the lack of interactions for proximate composition of meat and physicochemical properties of muscles only the main effects were reported. Statistical significance was set at P b 0.05 or P b 0.01.
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3. Results and discussion 3.1. Proximate composition The meat proximate composition and indices were given in Table 1. No differences (P N 0.05) in all constituents and indices were observed between beaver cuts. The meat from all cuts had a relatively high protein (between 20.88% and 21.45%) and low (between 0.96% and 1.95%) fat contents. Consequently, the energy value of meat regardless of cut was similar, ranged from 396 kJ 100 g−1 (loin) to 423 kJ 100 g−1 (shoulder). The meat from mature beavers contained significantly more protein (P b 0.01), but less fat and moisture (P b 0.01 and P b 0.05). Consequently, the significantly lower (P b 0.01) moisture:protein ratio and INQ for fat, but higher INQ for protein were found in meat from mature animals. A similar (P N 0.05) content of ash and energy value was determined in meat regardless animal age. The present study revealed that meat both young and mature beavers is a good source of protein, due to high values of INQ (2.03–2.24). In the present research protein and ash contents were close to those reported by Korzeniowski, Żmijewski, Jankowska, & Kwiatkowska (2002b) for meat (loin, thigh and tail mixture) of farmed beavers (22.09 and 1.33 g 100 g−1), and by Jankowska et al. (2005) for wild beavers (20.9–21.8% and 1.27–1.31%). Similar content of protein and ash to present results was also stated by Razmaitė et al. (2011) in thigh of wild beavers hunted in Lithuania (21.6 and 1.09%), and Strazdina et al. (2015) for biceps femoris of animals from Latvia (21.39 and 1.13%). In other investigation Korzeniowski, Kwiatkowska, Jankowska, & Żmijewski (2002a) did not find any influence of beaver weight (b10 kg, 10–20 kg, N20 kg) and sex (male vs. female) on the chemical composition of meat. Similarly, Tulley et al. (2000) found no differences in protein and moisture content when comparing male vs. female and young vs. old nutria caught in the wild. The fat content in present study was higher compared to Lithuanian research (0.51%) (Razmaitė et al., 2011), but lower than Latvian (4.29%) (Strazdina et al., 2015), and earlier Polish (3.8–4.6%) (Jankowska et al., 2005; Korzeniowski, Kwiatkowska, et al., 2002a) investigations. Although, no additional information about age or weight of beavers from Lithuania and Latvia were reported, it is well known that the lipids content in different tissues depends on the composition of diet and dietary habits of beavers (Czyżowski, Karpiński, & Drozd, 2009), as well as season (Razmaitė et al., 2011). The high content of fat in muscle tissue from young beavers may be related, among other factors, to the initial feeding stage, i.e. suckling period. The beaver weight at birth ranges between 320 and 770 g. In the age of 15 days this weight is already doubled, and during lactation (for approximately 60 days) the beavers reach the mean weight of 3.1 (2.0–4.8) kg. Rapid growth of kits is possible owing to high nutritive value of beaver females' milk, which is characterized by a high dry matter (in the range of 21.6 to 30%), fat
(8.2–17.6%) and total protein (8.0–10.0%) contents (Żurowski, Kisza, & Kruk, 1971). In present study no differences in energy value were found between cuts and beaver age. Higher energy compared to our results was reported by Korzeniowski, Kwiatkowska, et al. (2002a) for thigh and rump (492 and 516 kJ/100 g, respectively) from wild beaver males hunted in autumn. However, these differences might be explained by a higher fat content (thigh 3.5% and rump 4.1%) related to hunting season and the availability of the food resources. 3.2. Physicochemical properties Table 2 shows the effect of animal age, muscle type and storage on physicochemical properties of beaver meat. The meat of mature animals contained significantly (P b 0.05) more total pigments and showed significantly (P b 0.05) darker surface compared to young animals. Muscle type significantly influenced drip and cooking loss (P b 0.05) as well total pigments content (P b 0.01). Lower values of drip and cooking loss, but higher content of pigments showed SM than LTL. However, the significant impact of storage was observed for the most physicochemical properties, with the exception of pH and CIE colour characteristics. The TBARS value at 24 h was not very high, but significantly (P b 0.01) increased, even triplet initial level after 7 days post mortem. Nevertheless, this value was well below those threshold levels indicating rancidity or warmed-over flavour in pork - approximately 1.0 mg of MDA per kg tissue (Gray & Pearson, 1987) or in beef - 2.0 mg (Campo et al., 2006). The storage significantly (P b 0.01) increased drip and cooking loss after 7 days, compared to amounts at 24 h post mortem. Nevertheless, storage improved significantly meat tenderness (P b 0.01) and water holding capacity (P b 0.05). The studies on the technological parameters of meat obtained from large rodents are rarely published. However, some information for capybara was available in the literature. Bressan et al. (2004) reported similar pH (6.02) and shear force (50.9 N), but almost twice higher cooking loss (31.28%) in males longissimus dorsi after 24 h post mortem, compared to our results. In present study CIE L*, a* and b* values were determined only for SM muscle up to 7 days post mortem (Table 2); in the future it will be important to follow changes during longer storage for different muscles. Among colour coordinates, significant (P b 0.05) difference was stated only for lightness (L*). The SM muscle of mature beavers was darker (L* = 28.51) in comparison to meat of young animals (L* = 30.97). The dark colour of meat of mature beavers resulted from the significantly (P b 0.01) higher total pigment concentrations in comparison with young animals. Beaver muscles store large quantities of oxygen which results from the specific environmental conditions under which they live. In present study it was reflected by a high total pigment concentrations in LTL and SM which were greater than found in bovine meat, for
Table 1 Effect of carcass cut and animal age on proximate composition of beaver meat (mean ± standard deviation). Components and indices
Moisture (g 100 g−1) Protein (g 100 g−1) Fat (g 100 g−1) Ash (g 100 g−1) Moisture:protein ratio Energy (kJ 100 g−1) INQ for protein INQ for fat
Carcass cut (C)
Animal age (A)
P values
Loin n=6
Thigh n=6
Shoulder n=6
Young beaver (up to 1 year) n=9
Mature beaver (2–3 years) n=9
C
A
76.38 ± 0.63 21.45 ± 0.93 0.96 ± 0.51 1.16 ± 0.12 3.57 ± 0.18 396 ± 11.7 2.17 ± 0.11 0.07 ± 0.03
76.19 ± 0.61 21.36 ± 0.82 1.22 ± 0.68 1.19 ± 0.05 3.57 ± 0.16 404 ± 18.7 2.12 ± 0.14 0.09 ± 0.04
76.13 ± 0.57 20.88 ± 1.52 1.95 ± 0.75 1.19 ± 0.04 3.66 ± 0.29 423 ± 25.9 1.99 ± 0.26 0.13 ± 0.08
76.56b ± 0.51 20.52A ± 0.84 1.86B ± 0.81 1.19 ± 0.08 3.74B ± 0.17 414 ± 18.6 2.03A ± 0.14 0.13B ± 0.04
75.80a ± 0.38 22.16B ± 0.30 0.73A ± 0.19 1.18 ± 0.08 3.42A ± 0.10 399 ± 10.6 2.24B ± 0.08 0.05A ± 0.02
NS NS NS NS NS NS NS NS
⁎ ⁎⁎ ⁎⁎
INQ, index of nutritional quality. NS, not significant. Means in the same row with different letters are significantly different: a, b P b 0.05; A, B P b 0.01. ⁎ P b 0.05. ⁎⁎ P b 0.01.
NS ⁎⁎ NS ⁎⁎ ⁎⁎
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Table 2 Effect of animal age, muscle and storage on physicochemical properties of beaver meat (mean ± standard deviation). Characteristics
pH TBARS (mg MDA kg−1) Drip loss (%) Cooking loss (%) Expressible water (%) Spreadability (%) Shear force (N) Shear energy (J) Total pigments (ppm) CIE L* CIE a* CIE b*
Animal age (A)
Muscle (M)
Storage (S)
P values
Young beaver (up to 1 year) n = 12
Mature beaver (2–3 years) n = 12
LTL n = 12
SM n = 12
24 h n = 12
7 days n = 12
A
M
S
5.96 ± 0.13 0.31 ± 0.19 0.72 ± 0.28 18.42 ± 3.14 55.63 ± 5.22 44.36 ± 5.22 38.0 ± 10.6 0.14 ± 0.06 359A ± 56.3 30.97b ± 1.10 19.80 ± 0.94 −2.05 ± 0.50
6.09 ± 0.15 0.31 ± 0.20 0.79 ± 0.21 19.21 ± 3.59 53.93 ± 4.50 46.07 ± 4.50 48.7 ± 12.3 0.19 ± 0.09 608B ± 114.2 28.51a ± 1.04 18.73 ± 1.11 −2.19 ± 0.40
5.99 ± 0.17 0.26 ± 0.14 0.84b ± 0.29 19.58b ± 3.29 55.78 ± 4.13 44.21 ± 4.13 45.5 ± 12.1 0.17 ± 0.09 401A ± 111.5 – – –
6.06 ± 0.13 0.36 ± 0.23 0.65a ± 0.17 17.89a ± 3.16 54.13 ± 5.66 45.87 ± 5.66 40.1 ± 10.9 0.15 ± 0.06 517B ± 173.0 29.74 ± 1.41 19.27 ± 1.05 −2.12 ± 0.42
5.98 ± 0.14 0.15A ± 0.04 0.59A ± 0.11 15.99A ± 1.67 57.45b ± 4.03 42.55b ± 4.03 51.4B ± 11.4 0.21B ± 0.08 – 29.22 ± 1.64 19.59 ± 0.81 −1.96 ± 0.41
6.10 ± 0.14 0.46B ± 0.16 0.90B ± 0.26 21.49B ± 2.05 52.45a ± 4.52 47.55a ± 4.52 33.2A ± 6.0 0.11A ± 0.03 – 30.26 ± 1.53 19.69 ± 0.89 −2.28 ± 0.42
NS NS NS NS NS NS NS NS ⁎⁎ ⁎
NS NS ⁎ ⁎
NS ⁎⁎ ⁎⁎ ⁎⁎ ⁎ ⁎ ⁎⁎ ⁎⁎
NS NS
NS NS NS NS ⁎⁎ – – –
– NS NS NS
LTL, longissimus thoracis et lumborum; SM, semimembranosus; TBARS, 2-thiobarbituric acid reactive substances. CIE L* = black to white (0 to 100); CIE a* = negative green, positive red; CIE b* = negative blue, positive yellow. NS, not significant. Means in the same row with different letters are significantly different: a, b P b 0.05; A, B P b 0.01. ⁎ P b 0.05. ⁎⁎ P b 0.01.
instance veal (Florek, Litwińczuk, Skałecki & Grodzicki, 2009), beef (Litwińczuk et al., 2014) or buffalo meat (Malik & Sharma, 2010). There were no significant effects of beaver age or storage on a* and b* coordinates. However, the negative value of the b* indicated a bluish tint on the beaver SM surface after blooming. The higher values for L* and positive b*, whereas lower for a* (35.02, 1.85 and 9.88, respectively) compared to those in present trial were reported by Bressan et al. (2004) for longissimus dorsi of capybara males. Generally, taking into account the physicochemical properties, presented comparisons indicate that differences between beaver ages or muscle type were lesser than the differences between storage. Our findings point to an improvement of water holding capacity (reduction in expressible water and a low drip loss) and tenderness (reduction in shear force and shear energy) of beaver meat with 7 days storage. The shear force of beaver meat averaged 33.2 N after 7 days storage should be considered very tender (Belew, Brooks, Mckenna, & Savell, 2003). 4. Conclusions This pilot study showed that beaver meat is a rich and good source of protein, due to high value of nutritional quality index (INQ) as well as has a relatively low fat content. Additionally, colour of beaver meat is influenced by the total pigment concentrations, which increases with age. Results suggest that storage has a larger impact on technological properties and lipid oxidation (TBARS) compared to beaver age or muscle type. Furthermore, the tendency of tenderness improvement and water holding capacity after 7 days storage was revealed. Summing up, the future investigations are needed to understand presented observation, as well as widen the knowledge of this alternative red meat. Author contributions Designed the study: LD MF. Organized sample collection: LD KT. Performed the technological measurements: MF PS PD. Performed the chemical analysis: PD AL. Helped in data acquisition: KT. Analysed the data: MF PS PD. Performed the statistical analysis, drafted the manuscript and decided the submission of the article for publication: MF. Involved in the discussion of the manuscript: LD PS PD KT AL. All authors have read and approved the manuscript to be published. Conflict of interests There is no conflict of interest.
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