Effect of selection for growth rate on the ageing of myofibrils, meat texture properties and the muscle proteolytic potential of m. longissimus in rabbits

Effects of low voltage electrostatic field on the microstructural damage and protein structural changes in prepared beef steak during the freezing process

This study investigated the effect of low voltage electrostatic field (LVEF) on the microstructure damage and protein structure changes of prepared beef steak during freezing. The scanning electron microscopy results showed that LVEF-assisted freezing (LVEFF) minimized the gaps in the cross section between muscle fibers induced by freezing and thus improved fiber compactness. Furthermore, LVEFF reduced the length of the enlarged sarcomere, repaired the Z-line fractures, and intensified the dismission of the A band in the air-blast freezing (AF) process. The decreased carbonyl content and increased total sulfhydryl content indicated that LVEFF reduced protein oxidation in the freezing process. In addition, the results of Raman spectroscopy and fluorescence spectroscopy revealed that LVEFF minimized the changes in protein secondary and tertiary structures during freezing. In conclusion, utilization of LVEF in the freezing of prepared beef steak could reduce both the microstructure damage and protein structure changes in the freezing process.

Effect of Electrical and Mechanical Stunning on Rabbit Meat Quality Traits

Increased interest in the production of rabbit meat justifies the need to assess and improve the welfare of these animals not only during the production cycle but also at slaughter. Therefore, the aim of this study was to assess the effects of different stunning methods on the level of blood biochemical parameters (stress indicators), and meat quality of slaughter rabbits. Rabbits of the Hycole line (n = 60) were subjected to the following stunning methods: mechanical with a non-penetrating captive bolt (group I; n = 20), mechanical by hitting a narrow rod on the head (group II; n = 20), and electrical stunning (n = 20). In the stunning groups there were no differences found in the blood level of insulin, cortisol, glucose, total cholesterol, triglycerides, non-esterified fatty acids, and protein content (P>0.05). The stunning method did not affect the pH of rabbit meat (P=0.768), but significantly influenced the L* and b* colour parameters. The muscles of longissimus thoracis et lumborum, from the group of rabbits mechanically stunned by hitting a narrow rod on the head, were the darkest (L * = 58.4), with the lowest yellowness values (b* = 4.04). The meat of electrically stunned rabbits was characterised by higher drip loss (P<0.001), lower plasticity (P=0.043), and higher free water content (P=0.043). From the analysed texture measures, only the Warner Bratzler Shear Energy values of the cooked meat were affected by the stunning method. These values were higher in the meat of the mechanically stunned groups compared to the electrically stunned rabbits (P=0.042). The percentage of dry matter, crude protein, extractable fat and water to protein ratio, were affected only by the muscle type (P<0.001). To conclude, the rabbit meat was characterised by good quality, with only slight differences between the groups. No differences were found in the stress reaction of rabbits subjected to the examined stunning methods.

Effect of Two Different Stunning Methods on the Quality Traits of Rabbit Meat

Simple Summary

According to consumer opinion, poor welfare leads to lower quality animal products. The stunning method plays a very important role as far as animal welfare, meat quality, and public health are concerned. The aim of the presented study was to assess the effect of two different stunning methods on the blood stress indicators and the quality of rabbit meat. The underlying goal was to improve the welfare of rabbits at the time of slaughter. The study was conducted on a commercial rabbit farm in Poland. The hybrids used in this study were obtained crossing Hyplus PS19 females with Hycole males (genotype I) and Jordan × Hycole females with Hyla males (genotype II). According to the presented findings, the genotype groups of rabbits differed in meat performance, but the differences in meat quality were minor. The examination of the blood stress biomarkers showed that both stunning methods are optimal when taking the welfare of rabbits into consideration. The presented research revealed some differences in the physiochemical traits of meat, with only slight differences between genotypes and stunning methods.

Abstract

The aim of the study was to assess the effect of two different stunning methods on the level of blood stress indicators (cortisol, insulin, glucose) and rabbit meat quality. The experiment was conducted on crossbreds of Hycole, Hyla, and Jordan rabbit strains: from mating Hyplus PS19 females with Hycole males (genotype I, n = 20) and Jordan × Hycole females with Hyla males (genotype II, n = 20). Prior to slaughter, the animals were weighed and divided into two groups according to the stunning method: 10 rabbits from each genetic group were stunned with an electric stunner, and the remaining 10 were stunned mechanically using a club. Genotype II was characterised by higher body weight at slaughter (p < 0.05), hot dressing percentage (p < 0.05), cold dressing percentage (p < 0.05), hot carcass weight (p < 0.05), and cold carcass weight (p < 0.05), compared to genotype I. The stunning method slightly influenced the meat lightness (p = 0.035). The meat of electrically stunned rabbits was characterised with higher drip loss (p < 0.0001) and lower plasticity (p = 0.043). Among the analysed traits of meat, only the drip loss (p = 0.014) and the percentage of extractable fat were affected by genotype (p = 0.044). Neither the stunning method nor the genotype affected rabbit meat texture characteristics. The study was undertaken because of the increasing importance of rabbit meat production as a developing sector of the meat industry and the need to improve the welfare of rabbits by selecting the most acceptable slaughter methods for these animals. To conclude, the analysed rabbit meat was characterised with good quality. There were only slight differences between genotypes and the stunning groups.

The effects of hydrolysed sorghum on growth performance and meat quality of rabbits

<p class="Articletitle">The effect of sorghum hydrolysed by <em>Trametes maxima</em> CU1 and <em>Pycnoporus sanguineus</em> CS2 was evaluated on growth performance traits and rabbit meat quality. A total of 24 unsexed New Zealand rabbits, weaned at 20 d of age, were allocated to 2 treatments: T1 (diet including 300 g/kg of non-hydrolysed sorghum) and T2 (diet including 300 g/kg of hydrolysed sorghum by <em>Trametes maxima</em> CU1 and <em>Pycnoporus sanguineus</em> CS2). Rabbits of group T2 did not have significantly different (<em>P</em>&gt;0.05) feed intake compared to those in T1. Carcass traits were also not significantly different (<em>P</em>&gt;0.05) between the 2 groups. The pH, water-holding capacity, colour and cooking loss of the longissimus lumborum were not different (<em>P</em>&gt;0.05) between treatments, whereas the pH of the rabbits biceps femoris was higher in T2 (6.21; <em>P</em>&lt;0.05) than in T1 (6.14). Meat hardness and gumminess in T2 were lower (<em>P</em>&lt;0.05) in comparison to meat from T1. Thus, sorghum hydrolysed by <em>Trametes maxima</em> CU1 and <em>Pycnoporus sanguineus</em> CS2 contributed to a better rabbit meat texture.</p>

Comparison of myofibrillar protein degradation, antioxidant profile, fatty acids, metmyoglobin reducing activity, physicochemical properties and sensory attributes of gluteus medius and infraspinatus muscles in goats

BACKGROUND

The functionality of myofibrillar proteins is a major factor influencing the quality attributes of muscle foods. Nonetheless, the relationships between muscle type and oxidative changes in chevon during ageing are meagrely elucidated. Postmortem changes in antioxidant status and physicochemical properties of glycolytic gluteus medius (GM) and oxidative infraspinatus (IS) muscles in goats were compared.

METHODS

Twenty Boer bucks (9-10 months old, body weight of 36.9 ± 0.725 kg) were slaughtered and the carcasses were subjected to chill storage (4 ± 0.5 °C). Analyses were conducted on GM and IS muscles sampled on 0, 1, 4 and 7 d postmortem.

RESULTS

Chill storage did not affect the antioxidant enzyme activities in both muscles. The IS had greater (P < 0.05) superoxide dismutase and catalase activities than GM. Carotenoid and tocopherol contents did not differ between muscles but decreased (P < 0.05) over storage. The IS had higher (P < 0.05) glycogen and ultimate pH and lower (P < 0.05) shear force and cooking loss than GM. The carbonyl content, % metmyoglobin, drip loss and TBARS increased (P < 0.05) while free thiol, metmyoglobin reducing activity (MRA), shear force and myoglobin decreased (P < 0.05) over storage. Muscle type had no effect (P > 0.05) on free thiol, MRA and TBARS. The GM had lower (P < 0.05) redness on d 0 and 1 than IS while the IS had greater carbonyl, % metmyoglobin and drip loss than GM on d 7. The reflective density of slow myosin heavy chain (MHC) was higher (P < 0.05) while the density of fast MHC and actin was lower (P < 0.05) in IS than GM. Regardless of muscle type, the density of MHC decreased (P < 0.05) while that of actin was stable over storage. Nonetheless, the degradation of fast and slow MHC was greater (P < 0.05) in IS than GM. Muscle type had no effect (P > 0.05) on consumer preference for flavour, juiciness and overall acceptability. However, IS had higher (P < 0.05) tenderness score than GM on d 1 and 4 postmortem. Intramuscular fat was higher (P < 0.05) in IS compared with GM. Fatty acid composition did not differ between the muscles. However, GM had lower (P < 0.05) n-6/n-3 ratio than IS. The n-3 and n-6 PUFA declined (P < 0.05) while the SFA increased (P < 0.05) over storage.

CONCLUSION

The changes in myofibrillar proteins and physicochemical properties of goat meat during postmortem chill storage are muscle-dependent.

Analysis of the texture of rabbit meat subjected to different means of heat treatment

The aim of this study was to examine the influence of different types of heat treatment on the shear force and texture profile analysis (TPA) of rabbit meat. The research material was meat samples from 22 Blanc de Termonde rabbits. Two samples from the right loin (m. longissimus lumborum) were collected. The first sample was vacuum-packed in a plastic bag and frozen for 72 h at –18 °C; after thawing the samples were immersed in a water bath and boiled for 40 min at 80 °C. The second sample was placed in a plastic frozen-storage bag and frozen for 72 h at –18 °C; after thawing the samples were roasted at 180 °� � � � � � � � � � � � � � C to an internal temperature of 78 °� C. Shear force, hardness, springiness, cohesiveness and chewiness were measured. Significant differences in hardness, cohesiveness and chewiness were found depending on the type of heat treatment. The hardness of the boiled meat was 32% higher than that of the roasted meat, cohesiveness 10% higher, and chewiness 39% higher than in the case of the roasted meat.

Changes of microbial spoilage, lipid-protein oxidation and physicochemical properties during post mortem refrigerated storage of goat meat

Examined was the effect of post mortem refrigerated storage on microbial spoilage, lipid-protein oxidation and physicochemical traits of goat meat. Seven Boer bucks were slaughtered, eviscerated and aged for 24 h. The Longissimus lumborum (LL) and Semitendinosus (ST) muscles were excised and subjected to 13 days post mortem refrigerated storage. The pH, lipid and protein oxidation, tenderness, color and drip loss were determined in LL while microbiological analysis was performed on ST. Bacterial counts generally increased with increasing aging time and the limit for fresh meat was reached at day 14 post mortem. Significant differences were observed in malondialdehyde (MDA) content at day 7 of storage. The thiol concentration significantly reduced as aging time increased. The band intensities of myosin heavy chain (MHC) and troponin-T significantly decreased as storage progressed, while actin remained relatively stable. After 14 days of aging, tenderness showed significant improvement while muscle pH and drip loss reduced with increase in storage time. Samples aged for 14 days had higher lightness (P < 0.05) and lower (P < 0.05) yellowness and redness. Post mortem refrigerated storage influenced oxidative and microbial stability and physico-chemical properties of goat meat.

Tenderization of Bovine Longissimus Dorsi Muscle using Aqueous Extract from Sarcodon aspratus

The aim of this study was to investigate the effects of aqueous extract from Sarcodon aspratus on tenderization of the bovine longissimus dorsi muscles in comparison with commercial proteolytic enzymes. Furthermore, meat quality and muscle protein degradation were examined. We marinated meat with 2% Sarcodon aspratus extract, 2% kiwi extract, and 0.2% papain. Beef chunks (3×3×3 cm³) were marinated with distilled water (control), Sarcodon aspratus extract (T1), kiwi extract (T2) or papain (T3) for 48 h at 4℃. There were no significant differences in muscle pH and lightness between control and treated samples. T1 had the lowest redness (p<0.01), and higher cooking loss and water holding capacity than control and T2 (p<0.05). T1 and T3 exhibited lower shear force values than control (p<0.05). Total protein solubility did not differ significantly between T1 and control, but T1 had less myofibrillar protein solubility than control and T2 (p<0.001). The degradation of myosin heavy chain in T1 and T3 was observed. This degradation of myofibrillar protein suggests that Sarcodon aspratus extract could influence tenderization. These results show that aqueous extract of Sarcodon aspratus extract actively affect the tenderness of the bovine longissimus dorsi muscle.

Physico-chemical characteristics of Longissimus lumborum muscle in goats subjected to halal slaughter and anesthesia (halothane) pre-slaughter

This study assessed the effect of halal slaughter and anesthesia pre-slaughter followed by bleeding on meat quality characteristics of goats. Eleven male Boer cross goats were divided into two groups and subjected to either halal slaughter (HS) or anesthesia with halothane and propofol pre-slaughter (AS). At pre-rigor, HS had significantly lower (P < 0.05) muscle pH and glycogen than AS. However, no significant difference was observed in the pH and glycogen content between the treatments on 1, 3 and 7 days post mortem. The drip loss of HS was significantly lower (P < 0.05) than that of AS at all aging periods. Treatment had no effect on sarcomere length, myofibrillar fragmentation index and shear force values, loss of thiol groups and degradation of major myofibrillar proteins. It can be concluded that HS did not have deleterious effect on meat quality traits of goat when compared to AS.

Development of microbial spoilage and lipid and protein oxidation in rabbit meat

This experiment aimed to determine microbial spoilage and lipid and protein oxidation during aerobic refrigerated (4°C) storage of rabbit meat. Forty male New Zealand white rabbits were slaughtered according to the Halal slaughter procedure. The hind limbs were used for microbial analysis while the Longissimus lumborum m. was used for determination of lipid and protein oxidation. Bacterial counts generally increased with aging time and the limit for fresh meat (10(8)cfu/g) was reached at d 7 postmortem. Significant differences in malondialdehyde content were observed after 3d of storage. The thiol concentration significantly decreased with increase in aging time. The band intensities of myosin heavy chain and troponin T significantly reduced with increased refrigerated storage while actin remained relatively stable. This study thus proposes protein oxidation as a potential deteriorative change in refrigerated rabbit meat along with microbial spoilage and lipid oxidation.