Browsing by Subject "Meat quality"

Now showing 1 - 6 of 6
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    Development of high quality niche products from local chicken and pig genetic resources
    (2016) Muth, Philipp; Valle Zárate, Anne
    This thesis indicates that the application of non-conventional and/or slow-growing pig and chicken genotypes alone does not guarantee a superior and/or distinctive meat color and quality of the products. It appears that the valorization of monogastric meat products through niche marketing is critically dependent on matching the respective genotype with appropriate production methods, thus, for instance, highlighting the need for producers to be discerning in regard to the choice of slaughter age and feeding strategy. In the case that these premises are implemented, a distinguished positioning of meat products derived from local pig and chicken genetic resources can be realized, and, expanded by standards that also take the social and economic dimensions of food value chains into account, translated into a common pool resource as a basis for an alternative food network. Efforts should then be directed toward the elaboration of stable distribution channels and effective governance structures in the respective food network.
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    Genome-wide mapping and functional analysis of genes determining the meat quality in pigs
    (2014) Stratz, Patrick; Bennewitz, Jörn
    In chapter one QTL were mapped and tested for pairwise epistasis for meat quality traits in three connected porcine F2 crosses comprising around 1000 individuals. The crosses were derived from Chinese Meishan, European Wild Boar and Piétrain. The animals were genotyped genomewide for approximately 250 genetic markers and phenotyped for seven meat quality traits. QTL mapping was done using a multi-QTL multi-allele model. It considered additive (a), dominance (d) and imprinting (i) effects. The major gene RYR1:G.1843C>T affecting the meat quality was included as a cofactor in the model. The mapped QTL were tested for possible epistatic effects between the main effects, leading to nine orthogonal forms of epistasis (aa, ad, da, di, id, ai, ia, dd and ii). Numerous QTL were found; the most interesting are located on chromosome SSC6. Epistasis was significant (FDR q-value<0.2) for the pairwise QTL on SSC12 and SSC14 for pH 24 h after slaughter and for the QTL on SSC2 and SSC5 for rigour. In chapter two around 500 progeny tested Piétrain sires were genotyped with the PorcineSNP60 BeadChip. After data filtering around 48k SNPs were useable in this sample. These SNPs were used to conduct a genome-wide association analysis for growth, muscularity and meat quality traits. Because it is known, that a mutation in the RYR1 gene located on chromosome 6 shows a major effect on meat quality, this mutation was included in the models. Single-marker and multi-marker association analysis were performed. The results revealed between one and eight significant associations per trait with P-value<0.00005. Of special interest are SNPs located on SSC6, 10 and 15. In chapter three a literature search was conducted to search putative candidate genes in the vicinity of significant SNPs found in the association analysis. MYOD1 was suggested as putative candidate gene. The expression of MYOD1 was measured in muscle tissue from 20 Piétrain sires. Growth, muscularity and meat quality traits were available. DNA was isolated out of blood tissue to genotype the SNP ASGA0010149:g. 47980126G>A. Significant Correlations (FDR q-value<0.15) between the expression of MYOD1 and growth and muscularity traits were found. Association between the traits, respectively MYOD1, and ASGA0010149:g. 47980126G>A was tested, but was only significant (FDR q-value<0.15) for two muscularity traits. In chapter four the LD structure in the genome of the Piétrain pigs was characterized using data from the PorcineSNP60 BeadChip. The Relative Extended Haplotype Homozygosity test was conducted genome-wide to search for selection signatures using core haplotypes above a frequency of 0.25. The test was also conduct in targeted regions, where significant SNPs were already found in association analysis. A small subdivision of the population with regard to the geographical origin of the individuals was observed. As a measure of the extent of linkage disequilibrium, r2 was calculated genome-wide for SNP pairs with a distance 5Mb and was on average 0.34. Six selection signatures having a P-value<0.001 were genome-wide detected, located on SSC1, 2, 6 and 17. In targeted regions, it was possible to successfully annotate nine SNPs to core regions. Strong evidence for recent selection was not found in those regions. Three selection signatures with P-value<0.1 were detected on SSC2, 5 and 16. To reduce the costs of genomic selection, selection candidates can be genotyped with an SNP panel of reduced density (384 SNPs). The aim of chapter five was to investigate two strategies for the selection of SNPs to be considered in the above mentioned SNP panel, using 895 progeny tested and genotyped German Piétrain boars. In the first strategy equal spaced SNPs were selected, which were used to impute the high density genotypes. In the second strategy SNPs were selected based on results of association analysis. Direct genomic values were estimated with GBLUP from deregressed estimated breeding values. Accuracies of direct genomic values for the two strategies were obtained from cross validation. A regression approach to correct for the upward bias of the cross validation accuracy of the direct genomic values was used. The first strategy resulted in more accurate direct genomic values. This implies that imputation is beneficial even if only 384 SNPs are genotyped for the selection candidates.
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    Influence of transport distance, animal weight, and muscle position on the quality factors of meat of young bulls during the summer months
    (2024) Poveda-Arteaga, Alejandro; Bobe, Alexander; Krell, Johannes; Heinz, Volker; Terjung, Nino; Tomasevic, Igor; Gibis, Monika
    This study investigated the potential effects of transport distance, animal weight, and muscle position on meat quality in young bulls under commercial conditions across four slaughtering weeks during the summer months (May to September). Data on transport distance, lairage time, and ambient temperature during slaughtering days were collected from 80 young bulls from North German farms. Meat quality parameters, including pH, temperature, and meat color were also recorded at several post-mortem times from two different carcass locations (shoulder clod and silverside). Meat texture was evaluated both by sensory and instrumental analysis, and their values were compared to find possible correlations between them. All of the aforementioned main factors (transport distance, animal weight, and muscle position), as well as the interaction between animal weight and transport distance, significantly influenced (p < 0.01) meat quality traits. The results of the assessment of the meat texture from the cooked meat patties suggested that silverside cuts were consistently harder than shoulder clod cuts, despite having lower pH48 values.
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    Physiologische und genetische Einflüsse auf die Qualität von Schweinefleisch aus baden-württembergischen Gebrauchskreuzungen
    (2012) Fecke, Anna; Weiler, Ulrike
    What genotypes, basing on the genetic lines supplied by German Genetic, guarantees both a high-value carcass and excellent pork quality and high eating quality and also how the criteria of fertility, weight development and yield at slaughter, relate to the criteria of pork quality. 10 genotypes were studied. Therefore the sows crossbred represent typically genotypes in Baden-Württemberg as well as the Leicoma hybrid sows. These sows were bred at the LSZ Boxberg with Pietrain and Duroc boars. The sows of the LW*(LC*DL) had the highest fertility rate. The boar lines showed no influence on either the birth weight or fertility parameters. The boar line, however, did reflect a highly significant influence on the daily gain in all further production periods (Duroc vs. Pietrain: suckling +8%; rearing +3,8%; fattening +6,5%).The offspring from the sows LW*(LC*DL) had the greatest daily gain in the suckling period and had a higher weaning weight (+6%, p<0.05) than the offspring from the LW*(SH*DL), which achieved the lowest overall weaning weight. On analyzing the relationship between the development weights in the various production periods and the birth weight, it was obvious that the birth weight provides a significant positive influence on the performance in every production period, except for rearing. Indeed, in the rearing period the animals with a high birth weight tended to show low daily gains, whereas the piglets with a low birth weight were able to partially compensate for the early growth deficit during this period. The Pietrain offspring had more lean meat content than the Duroc offspring. The dissection in Trial #2 shows that the Pietrain offspring had 3.3% more ham content and 4.0% more of the valuable cuts. The Duroc offspring had less lean meat content in the belly (-4.2%, Gruber Formula), more back fat (+13.7%), more leaf fat (+14.6%), and 12.5% more corrected fat area than the Pietrain offspring. The offspring of the sows LC*LW had a significantly shorter carcass than the offspring of the other sows. The offspring from the 50% Leicoma sows showed the greatest corrected fat area. The offspring from the sows LW*(LC*DL) had 17.1% less corrected fat area. The correlation analysis resulted in the established relationships. Especially of a practical interest, is the close relationship between lean meat content (FOM) and the pork underbelly (Gruber Formula) (r=0.92; n=240; p<0.001). For nearly every parameter the results of the pork quality grading under practical conditions (Trial #1) tended toward improved values for the pigs with Duroc genes, which showed a significantly lower drip loss. The influence of the sows on pork quality parameters was negligible. Besides these parameters, some carcasses were also characterized with PSE qualities (pH1<5.8; conductivity 24hr p.m.>8.0mS/cm). In Trial #1, based on the pH-readings at the slaughterhouse, almost no carcasses (0.15%) were identified with PSE, whereas the conductivity measurements in ham, 5.79% of the carcasses were identified as PSE. In Trial #2, 15.0% of the animals were PSE based on pH1 or conductivity measurements in the loin and ham. There were 5 carcasses which have PSE after both measurements in loin and ham. In the histochemical analysis of the muscle fiber classification the only difference between the boar lines was found in the percentage of red fibers. The eating quality tests revealed an influence from the boar line. In general, all genotypes produced a high quality lean meat content according to the market requirements. As to expectation the improved pork quality of the Duroc breed was justified by the best eating quality, an improved water-holding capacity and a higher intramuscular fat content. An acceptable overall pork quality can be achieved by pairing the offspring from the Pietrain*LW*(LC*DL). The offspring with some Schwäbisch-Hall genes have an opportunity to establish a regional market. However, their performance was not convincing because in fertility, in daily gain, and even in pork quality they attained below average values. Nevertheless, an optimal pork quality can be achieved more efficiently with other genotypes. On establishing predicting criteria, the percentage of PSE of the pork carcasses is quite positive. The superiority of the 24hr p.m. conductivity value for the drip loss predict is evident here. The measurement of the conductivity subsume the effects of slaughtering and cooling and is more appropriate than the pH1 value, especially, for the incoming inspection in the deboning area as well as for quality assurance.
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    Das Potenzial der teilmobilen Schlachtung von Rindern im Herkunftsbetrieb : Stressbelastung und Fleischqualität
    (2022) Zeidler, Johannes
    The industrialization of animal husbandry and the focus on large production volumes have led to the killing of farm animals taking place almost exclusively in what are now a few large slaughterhouses. Of the approximately 3.4 Mio cattle slaughtered in Germany in 2019, nearly 78% are slaughtered in Germanys 10 largest slaughterhouses. Local butchers and small slaughterhouses often cannot comply with the strict legal hygiene regulations. The animals must therefore be transported alive, where loading, the journey, the foreign environment, the separation from the herd and the meeting with unfamiliar animals and humans, are known to cause stress and as well have negative impacts on meat quality. Since the revision of the EU regulation 853/2004 in 2021, slaughter at the farm of origin is now considered an official slaughter method. Although research focussing on slaughtering cattle on the farm of origin using captive bold stunning is missing, meat of cattle slaughtered via gunshot on pasture tends to be more tender and stress levels can be reduced in comparison to cattle slaughtered in the slaughterhouse. This leads to the assumption that also slaughtering cattle on the farm of origin, using captive bolt stunning, should result in higher meat quality and reduce stress prior to slaughter. For this purpose, this study examined 27 cattle from seven different farms slaughtered either on farm of origin using captive bolt stunning, via gunshot or in commercial slaughterhouses. Meat quality parameters and stress indicators were assessed to evaluate these three slaughter methods from a meat quality and an animal welfare perspective Based on the cortisol levels in the blood of exsanguination, no significant differences in the stress levels of the different slaughter methods could be determined. Nevertheless, tendencies towards less stressed animals with slaughtered via gunshot and slaughtered on the farm of origin using captive bolt stunning compared to the slaughterhouse could be revealed. As large variances of cortisol concentrations were measured within cattle slaughtered on farm of origin, stress level seems to depend on the individual slaughtering and preparing procedure. Further research is needed to improve and give recommendations for practical implementation of this method taking different farm structures into account. Quality parameters were not unambiguous. A significant effect of the slaughter method could only be found on ultimate pH-value and redness (a* L*a*b* System). Contrary to our expectations, ultimate pH-value was significantly lower in meat of cattle slaughtered on farm of origin using captive bolt stunning than in meat of cattle slaughtered via gunshot. Moreover, cattle slaughtered on farm of origin using captive bold, had significantly redder meat than cattle slaughtered via gunshot This contradicts the assumption that more stress leads to less red meat. However, it is consistent with the lower pH values of meat from cattle slaughtered with bolt stunning at the farm of origin, because low pH values lead to redder meat. Exploratory results comparing only meat from commercial slaughterhouses with meat from cattle slaughtered on farm using captive bolt stunning show clearer trends. Lower ultimate pH-values, as well as trends towards more tender and juicy meat could be found in cattle slaughtered on farm. To ensure these results and to evaluate meat quality according to different slaughter methods in upcoming research, either environmental effects should be reduced, or the dataset must be larger.
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    Process, structure and function relationship in ground meat
    (2023) Berger, Lisa Marie; Weiss, Jochen
    Ground beef has enjoyed high popularity with consumers because it is convenient to use and facilitates a rapid preparation of a large variety of different meals. In the production of ground meat, the particle size of the meat is systematically reduced, and the cell structures are partially disintegrated. Ideally, the original cellular meat or fat structure is preserved as much as possible so that important quality attributes are optimized. However, the effect of varying conditions and parameters in modern processes on the quality of ground meat has not yet been investigated in detail. According to the current German “Leitsätze für Fleisch und Fleischerzeugnisse”, hamburgers must not contain more than 20 Vol.% of non-intact cell structures to be sold without further declaration. Therefore, this work aimed to identify process, structure, and function relationships in ground meat production to facilitate a gentler processing of in particular hamburgers. To investigate these effects systematically, a standardized production method for hamburgers was developed and a pilot plant scale meat grinder was set up with the possibility to record process-relevant data. The relationship between the structure and functionality of ground meat was investigated using a model system with increasing amounts of added meat batter to simulate changes in meat structure due to cell disintegration. A new term, i.e., the amount of non-intact cells (ANIC), was introduced to quantify the amount of disintegrated meat cells during processing. It was shown that changes in the structure due to a higher or lower ANIC resulted in altered physicochemical and functional properties of the ground meat system. The effect of frozen meat content and temperature on the structure and function of hamburgers was investigated to verify the above-obtained correlation to an application-relevant setting. As the specific cutting resistance is significantly higher in frozen than in chilled meat, it was assumed, that the impact on the ground meat’s structure and function differed accordingly. Indeed, this could be verified. In hamburger manufacturing, it is common practice to re-fed imperfectly molded patties, e.g., in a frozen, coarsely crushed state. In contrast to those findings, the use of up to 20 % re-fed material in hamburger manufacturing did not result in any noticeable differences as neither the specific mechanical energy input (SME) nor the ANIC was significantly changed. It was thus demonstrated, that some raw material variations can have an impact on both structure and function of hamburgers. Especially, temperature effects and associated changes in the cutting resistance of the raw material had the strongest influence on structure and function of ground meat. However, if structural differences were found, they were not sufficient to manifest in differences in sensory evaluation. This means that the consumer perception and thus the quality of the hamburger was not influenced. The process parameters and their impact on the structure and function of hamburgers were studied by investigating the impact of the four main processing steps pre-grinding, mixing, grinding, and forming. An increased ANIC was determined with progressive processing, whereby the grinding steps accounted for the strongest increase. Mixing and forming were of minor importance for structural and functional changes. By varying the cutting set parameters, the influence of the cutting set compositions on the structure and function of hamburgers was assessed. The SME and the ANIC increased if more cutting levels were used due to higher shear stress applied to the meat. However, the hole plate properties did cause no or only negligible changes in the ANIC and SME. Although an impact of the cutting set composition on the structure could be found, no or only marginal effects on the function and the sensory and optical quality of the hamburgers were found. It can therefore be concluded that the shear forces acting on the meat during grinding have the strongest influence on the structure and function of beef. By reducing the acting shear forces, the grinding can be designed to be gentler resulting in lower ANIC. Despite the influence on the process-control (SME, pressure, torque) and the structural parameters (ANIC), it needs to be emphasized that the influence on the function and quality of the hamburgers is small in application-relevant ranges. In application-relevant ranges this relationship is only slightly pronounced. Comparable results were found, as raw material variations only partially caused structural, functional, and quality effects in the hamburgers. This in turn means that changes in structure cannot always be linked to a shift in perceived quality. In order to carry out an integrated evaluation of the product, structural parameters and quality parameters must be defined, assessed separately, and merged into a combined overall sample assessment.