The aim of this study was to evaluate the effect of enzymatic modification of poultry myofibril preparation on its selected functional properties, that is, solubility of proteins, polymerisation rates of myosin and actin, thermodynamic properties and texture. The myofibril preparation (MP) from mechanically recovered chicken meat, produced by washing and separation of fat and connective tissue, was subjected to the action of the transglutaminase preparation added at 0.3 % for a period ranging from 0.5 to 24 h at a temperature of 6-7°C. The highest dynamics of a reduction in protein solubility was observed up to 3 h of incubation. A reduction in solubility influenced the electrophoretic pattern of proteins. A significant decrease was found for the intensity of the myosin band in successive modification periods. The addition of the enzyme also influenced a reduction in enthalpy for proteins of the tested system, occurring most dynamically up to 3 h of incubation. The most distinct changes characterising a high increase in all the texture parameters of MP were found in the initial period of enzymatic modification, that is, up to 4.5 h.

of the meat tenderness using canonical correlation analysis. Based on the percentage participation of the selected muscle tissue and centrifugal drip proteins and measurements of pH and EC at specified time pm it was possible to predict tenderness with a very high probability, even 89%.

The objective of this study was to estimate the impact of the polymorphism of μ-calpain (CAPN1S) gene on protein changes of the cattle muscle tissue and its tenderness during 10-day cold storage. The analysis was performed on the longest dorsal and lumbar muscles collected from 76 bulls 6 to 12 months of age. Polymorphism identification of the above-mentioned gene was conducted using the PCR-RFLP technique. Its effect on the course of the proteolysis process was assessed by monitoring changes in proportions of tissue proteins during 10-day process of meat ageing. Special attention was focused on changes in native titin (T1) share and products of its degradation (proteins of molecular weight (m.w.) of 2400 and 200 kDa), α-actinin and protein of 37 kDa as well as myosin heavy chains (MHC). In the case of the last proteins, their polymorphism was evaluated as well. Meat tenderness was estimated measuring the value of shear force and sensorially. The highest tenderness was ascertained for the heterozygote. Its improvement was associated with a significant decrease in proportions of proteins of molecular weight of approximately 37 kDa accompanied by an increase of those with 200 kDa molecular weight. Muscles derived from cattle of CT genotype were characterised by the highest proportions of type 2a MHC isoform. Value differences between proportions determined for the heterozygote and CC and TT homozygotes of the CAPN1S gene were statistically significant. Therefore, it can be presumed that the process of meat tenderisation was especially connected with MHC polymorphism.

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Abstract. The aim of the investigations was to analyse the share of myosin heavy chains (MHC) isoforms (type I, IIa, IIb, and IIx) in the longissimus thoracis et lumborum muscle derived from pigs of different RYR1 genotypes (TT – homozygous negative, CT – heterozygous, CC – homozygous positive). The composition of the MHC isoforms in the muscle tissue of the examined animals was referred to selected meat quality traits. It was revealed that the animals with the CT and TT genotypes were characterized by a significantly (P≤0.05) lower share of the type I and higher share of the type IIb MHC isoform in comparison to homozygotes CC. Inferior tenderness and water holding capacity of meat obtained from pigs susceptible to stress (TT) at 144 h after slaughter could have been associated, among others things, with the increased share of MHC isoform type IIb. The composition of MHC isoforms might be a useful indicator in breeding work in the selection of animals carrying the gene of susceptibility to stress.

The aim of this study was to compare the quality of meat of the young Limousin bulls slaughtered at the age of 6, 9 and 12 months, with particular regard to the residual glycogen content in the meat and the value of the glycolytic potential. The study was conducted on bovine longissimus lumborum muscle. The residual glycogen content, glycolytic potential value (96 h post-mortem), pH value (45 min, 24 h, 48 h and 96 h post-mortem), IMP/ATP index (45 min post-mortem), colour parameters (L*, a* and b*), natural and cooking losses, free water content, the chemical composition, sensory parameters (aroma, flavour, juiciness and tenderness) as well as instrumental tenderness based on cutting test (96 h post-mortem) were analysed. The slaughter age of bulls had significant (p<0.05) effect on following meat parameters: concentration of glycogen, glycolytic potential value, lightness (L*) and redness (a*), shear force value, intramuscular fat content and sensory evaluation of aroma, flavour, juiciness and tenderness.  The longissimus lumborum muscle from young bulls slaughtered at the age of 6 months had significantly (p<0.05) lower values for glycogen concentration, glycolytic potential and intramuscular fat content when compared to animals slaughtered at the age of 12 months. Moreover, the colour of the examined muscle from the youngest bulls was characterised by the highest L* value and the lowest a* value as well as the lowest shear force value when compared to the meat of older bulls slaughtered at the age of 9 and 12 months.

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The aim of the study was to evaluate the post mortem proteolysis of centrifugal drip protein derived from pork. The varied course of the process of meat tenderization in muscles using the isoelectric focusing (IEF) technique was observed. The experimental material was the longissimus lumborum et thoracis muscle excised from 24 pigs of known origin, breeding and rearing conditions. Meat of normal quality (RFN) was examined in this study. On the basis of shear force values, the experimental muscles were divided into 4 groups of different courses of tenderization: A – meat remaining tough during the entire 6-day period of post-slaughter changes; B – meat characterized by a typical tenderization process, i.e. tough 48 h after slaughter and tender after 6 days of storage; C – tender or relatively tender meat on both dates of examination; D – meat which was the toughest 48 hours after slaughter and the most tender 144 hours after slaughter. Proteins for electrophoretic analysis on the agarose gel of the centrifugal drip fraction were submitted after 48 h and 144 h post mortem. The separation of the proteins was performed in a horizontal layout, using an FBE-3000 apparatus and an ECPS power pack (Pharmacia). On every path of the proteins separation, four ranges of pH value were evaluated, namely: 4.0 ÷ 6.0 pI, 6.1 ÷ 7.2 pI, 7.3 ÷ 7.7 pI and > 7.7 pI. Meat tenderness on the second day after slaughter was influenced by proteins, in which their pI was in the range of 6.1÷ 7.2 and 4.0 ÷ 6.0. From the evaluation which was carried out in the immunoblotting analysis of proteins using troponin T (9D) antibodies it was demonstrated that 48 h after slaughtering the most intense reactions were observed in the range of pI of 5.5 ÷ 5.9, which is the pH range corresponding to the isoelectric point of troponin T. However, after 144 h post mortem the most intense reaction was demonstrated in the range of pI of 6.1÷ 7.7. This indicates the breakdown of troponin T and an increase of the number of degradation products of this protein occurring while the meat tenderization process progresses. The degradation products of troponin T identified by IEF can be an indicator of meat tenderization.