The thermal shrinkage force in perimysium from different beef muscles is not affected by post-mortem ageing

Mechanism of textural properties changes of cooked chicken in early postmortem: Effect of protein degradation induced by calpain on heating shrinkage

Although the relationship between myofibrillar protein status and cooked meat quality is well documented, its underlying mechanism still need to be clarified. In this study, the effect of calpain-induced myofibrillar degradation on the cooked chicken quality was discussed by comparing the difference in muscle fiber's heat shrinkage state. In early postmortem, the protein around Z-line was degraded, which would cause the unstable Z-line and released into the sarcoplasm, according to WB results. This phenomenon will aggravate the lateral contraction of muscle fragments during the heating process. Then along comes a higher cooking loss and lower texture properties of meat. Above findings indicate that the Z-line dissociation caused by calpain in the early postmortem period is an essential reason for the quality difference of mature chicken. This study provided a fresh light on the mechanism underlying the impact of myofibril degradation in the early postmortem on the quality of cooked chicken.

Structural changes in collagen and aggrecan during extended aging may improve beef tenderness

The aim of this study was to characterize structural and property modifications of intramuscular connective tissue (IMCT) during extended aging. Longissimus lumborum (LL), Gluteus medius (GM), and Gastrocnemius (GT) muscles were collected from 10 USDA choice carcasses, fabricated and assigned to one of four aging periods: 3, 21, 42, or 63 days (n = 120). As expected, tenderness improved, and IMCT texture weakened after 21 days of postmortem aging (dpm; P < 0.05). In addition, transition temperature of collagen decreased (P < 0.01) after 42 dpm. It is interesting to note the collagen structure was also altered where relative % of γ chain decreased after 42 dpm (P < 0.05), and the α1 chain % increased at 63 days (P < 0.01). Finally, The LL and GT had a decrease in the 75 kDa aggrecan fragments from 3 to 21 to 42 dpm (P < 0.05). This study provided evidence that IMCT weakens during postmortem aging due to the modifications of IMCT components such as collagen and proteoglycan.

Role of Intramuscular Connective Tissue in Water Holding Capacity of Porcine Muscles

BACKGROUND

This study evaluated the influence of intramuscular connective tissue (IMCT) on structural shrinkage and water loss during cooking. Longissimus thoracis (LT), semimembranosus (SM) and semitendinosus (ST) muscles were cut and boiled for 30 min in boiling water, followed by detection of water holding capacity (WHC), tenderness, fiber volume shrinkage and protein denaturation.

RESULTS

Compared with LT and SM, ST had the best WHC and lowest WBSF and area shrinkage ratio. The mobility of immobilized water (T22) was key to holding the water of meat. ST contained the highest content of total and heat-soluble collagen. On the contrary, ST showed the lowest content of cross-links and decorin, which indicate the IMCT strength of ST is weaker than the other two. The heat-soluble collagen is positively correlated to T22.

CONCLUSIONS

The shrinkage of heat-insoluble IMCT on WHC and WBSF may partly depend on the structural strength changes of IMCT components rather than solely caused by quantitative changes of IMCT.

Shrinkage Properties and Their Relationship with Degradation of Proteins Linking the Endomysium and Myofibril in Lamb Meat Submitted to Heating or Air Drying

The shrinkage of the connective tissue and myofiber of lamb meat submitted to heat treatment or air drying at different storage stages (1, 5 and 7 days) was evaluated herein. The longitudinal and transverse shrinkage of heated lamb meat was significantly influenced by storage time and water bath heating temperature (50 °C, 70 °C and 90 °C) (p < 0.001). In contrast, the shrinkage of air-dried lamb meat was not influenced by storage time (p > 0.05). The microstructure of heated lamb meat, namely, the distance between muscle fascicles, the distance between myofibril networks, the area of myofibril networks, and the endomysium circumference, was significantly influenced by storage time (p < 0.05). During storage, the proportion of muscle fibers completely detached from endomysium increased, which could be due to the progressive degradation of proteins linking the endomysium and myofibril, including β-dystroglycan, α-dystroglycan, integrin-β1, and dystrophin. However, degradation of such proteins did not influence the shrinkage of lamb meat stored for five days or longer, since the decreased distance between myofibril networks indicated a higher shrinkage ratio of the endomysium compared to myofibers in samples air-dried at 35 °C or heated at 90 °C. The effect of these proteins on the shrinkage of heated lamb meat (raw meat stored for 1 day or less time) requires further elucidation.

A linear systems model of the hydrothermal isometric tension test for assessing collagenous tissue quality

Collagen is the most abundant structural protein in the animal kingdom. Its thermal and thermomechanical properties are often measured using differential scanning calorimetry (DSC) and hydrothermal isometric tension (HIT) tests, respectively. In living tissues, not all collagenous structures (molecules, fibrils, etc.) have the same "quality," and the heterogeneity among these structures in specific tissues increases with remodeling, aging, and/or disease states. In this paper, first, a peak-fitting analysis is carried out to separate and distinguish the sequential denaturation events in a DSC endotherm, which presumably stem from heterogeneity in the collagen fibrils. The fitting analysis uses one of two functions: a Gaussian function or a function proposed by Miles. The individual endotherms were then convolved with a physics-based parametric function, J(T), proposed by the authors, to model the development of the isometric tension in two stages: 1) tension development due to a sudden increase in conformational entropy as each collagen packet denatures, and 2) additional isometric tension development due to increasing temperature, consistent with rubber thermo-elasticity. The proposed function parameters were then found by fitting to actual HIT curves using a global optimization technique. This model provides a decoupling of the effects of denaturation kinetics and collagen network connectivity and therefore an improved interpretation of HIT test results during the temperature ramp from ambient temperature to 90 °C. The simple model outputs are two parameters, α and β, that have physical meaning and aid in assessing collagenous tissue quality in terms of connectivity and integrity.

Meat tenderness: advances in biology, biochemistry, molecular mechanisms and new technologies

Meat tenderness is an important quality trait critical to consumer acceptance, and determines satisfaction, repeat purchase and willingness-to-pay premium prices. Recent advances in tenderness research from a variety of perspectives are presented. Our understanding of molecular factors influencing tenderization are discussed in relation to glycolysis, calcium release, protease activation, apoptosis and heat shock proteins, the use of proteomic analysis for monitoring changes, proteomic biomarkers and oxidative/nitrosative stress. Each of these structural, metabolic and molecular determinants of meat tenderness are then discussed in greater detail in relation to animal variation, postmortem influences, and changes during cooking, with a focus on recent advances. Innovations in postmortem technologies and enzymes for meat tenderization are discussed including their potential commercial application. Continued success of the meat industry relies on ongoing advances in our understanding, and in industry innovation. The recent advances in fundamental and applied research on meat tenderness in relation to the various sectors of the supply chain will enable such innovation.

Insight into the Effects of Sous Vide on Cathepsin B and L Activities, Protein Degradation and the Ultrastructure of Beef

This study aimed to evaluate the effects of sous vide cooking (SV) on beef tenderness and its underlying potential mechanism. Beef semimembranosus (SM) were subjected to SV treatments at 45 °C, 55 °C and 65 °C for 4 h. Compared with control samples (CK, cooked at 75 °C until a core temperature of 72 °C was attained), SV treatment significantly promoted the release of cathepsin B and cathepsin L from lysosomes and decreased the shear force of beef SM (p < 0.05). In comparison with CK, samples treated with SV had more hydrolysis of myosin heavy chain and obtained higher myofibrillar fragmentation index, collagen solubility as well as longer sarcomere length (p < 0.05). The current study showed that the proteolysis of myofibrillar protein and collagen induced by cathepsin B and cathepsin L, and the limited longitudinal shrinkage together contributed to the improvement of beef tenderness upon SV.

Muscle, Ageing and Temperature Influence the Changes in Texture, Cooking Loss and Shrinkage of Cooked Beef

This study aimed to quantify the effect of muscle, ageing and cooking temperature on the texture, cooking loss and shrinkage of cooked beef. Cuboids from unaged (1 day post mortem) and aged (14 days post mortem) semitendinosus, biceps femoris and psoas major muscles, from both sides of five beef carcasses, were cooked at four different cooking temperatures (50, 60, 70 and 80 °C) for 30 min. and their Warner-Bratzler shear force (WBSF), cooking loss and shrinkage (longitudinal and transverse) were quantified. The WBSF was reduced by ageing in the muscles at the specific cooking temperatures: psoas major (cooked at 50, 60 and 80 °C), semitendinosus (70 and 80 °C) and biceps femoris (80 °C). The cooking loss was 3% greater in aged compared to unaged muscles. The longitudinal shrinkage was greatest in psoas major at 80 °C amongst the muscle types and it was reduced by ageing in psoas major (70 and 80 °C) and biceps femoris (80 °C). The transverse shrinkage was reduced by ageing only in biceps femoris, across all temperatures; and the diameter of homogenized fibre fragments from semitendinosus and biceps femoris was reduced more by cooking at 50 °C in unaged compared to aged condition. WBSF was related to transverse shrinkage, and cooking loss was related to longitudinal shrinkage. The effect of muscle type on the physical changes occurring during cooking of beef is dependent on ageing and cooking temperature.

Cooking of meat: effect on texture, cooking loss and microbiological quality – a review

Cooking can positively affect meat tenderness, on the other hand, the heat treatment also causes weight loss. The resulting tenderness of cooked meat is influenced by the background toughness of fresh meat, by the post mortem ageing process and by the method of cooking. In the case of heat treatment, the temperature and duration of action play a key role. In this respect, the meat tenderness depends on the type of appliance used for cooking. The cooking loss of meat during heat treatment is caused by contraction of muscle fibres and intramuscular connective tissue, the intensity of which also depends on the temperature and device used. The extent of this contraction increases with increasing temperature. Cooking of meat is considered the most effective way of eliminating microorganisms causing food-borne diseases. The recommended combination of temperature and time of 70 °C for 2 min reduces the number of Listeria monocytogenes bacteria by more than 6 log. This temperature is not, however, always attained with the use of many meat cooking methods, such as grilling or frying. This presents the risk of survival of food-borne agents. The latest knowledge indicates that, in the case of cross contamination, the population of food-borne agents is of the order of 1–2 log CFU/cm2 or g. If they do not multiply as a result of a higher environmental temperature, the population of pathogenic bacteria present is then reliably eliminated during adequate cooking, either entirely or to an amount that does not suffice to induce illness.

Single-nucleotide polymorphisms for matrix metalloprotease-1 can affect perimysial strength and intramuscular fat content but not growth rate of cattle

Context Single-nucleotide polymorphisms (SNPs) in the gene coding for matrix metalloprotease-1 (MMP-1) are known to affect the level of intramuscular fat found in cattle. As well as a signalling molecule affecting adipogenesis, MMP-1 is a major collagenase involved in the turnover of connective tissue. Aims The aim of the work was to assess whether SNPs in the gene for MMP-1 may affect the mechanical properties of intramuscular connective tissue, and therefore meat texture. Methods Allelic frequencies of three SNPs for MMP-1 were determined in a group of black Aberdeen Angus cattle whose growth characteristics had been traced for 450 days before slaughter. Associations between the alleles of each of the three SNPs and growth rate, killing out percentage, half-carcass weight, intramuscular fat content, cooking loss, strength of perimysium in cooked M. semitendinosus and Warner–Bratzler peak force of cooked M. longissimus dorsi were studied. Key results None of the SNPs studied had any effect on growth curves, and only one SNP (ss77831914) showed differences in half-carcass weight between alleles. Carcass yield and killing out percentage showed a small difference between alleles of ss7783924. No effects were found on the Warner–Bratzler peak force of M. longissimus dorsi cooked to 70°C. Two SNPs (ss77831914 and ss77831924) showed significant differences between alleles in the raw strength of perimysium in M. semitendinosus and the amount of intramuscular fat. Conclusions Commonly occurring SNPs of the major collagenase MMP-1 can affect the strength of intramuscular connective tissue as well as intramuscular fat content. Although these differences in connective tissue strength do not influence Warner–Bratzler measures of toughness at a cooking temperature of 70°C, they may contribute to differences in toughness in low-temperature, long-time cooking. Implications Because none of the SNPs had effects on the growth curves of the cattle studied, selection of animals with the relevant alleles of SNPs ss77831914 ss77831924 could be used to produce more tender meat without affecting carcass yield.

Physicochemical, thermal and mechanical characterization study of perimysial collagen of two bovine muscles

Chemical, thermal and mechanical collagen characteristics of intramuscular perimysial connective tissue (IMCT) from bovine Semitendinosus (ST) and Pectoralis profundus (PP) muscles were studied. Furthermore, these collagen characteristics in presence/absence of other extracellular matrix components were analyzed for both muscles. Differences between muscles were observed for collagen content; all IMCT-PP perimysial samples were higher than ST samples. In addition, for both muscles, IMCT-alkali resistant samples allowed the highest trypsin soluble collagen. The main differences between muscles were recorder for thermal and mechanical properties. The denaturation of collagen in the perimysium evidenced differences in total denaturation energy (ΔH) and peak temperatures (Tp). The ΔH resulted higher for IMCT-PP than for IMCT-ST tissues in all samples. By the tensile test it was observed that the maximum loads were constant and higher in all PP samples. In the FTIR assay, the peaks for the main amides were registered in both tissues. However, slight differences between ST and PP-IMCT were detected on hydrogen bond interactions and in secondary structure of the protein. The results reinforce the hypothesis of the presence of different IMCT-perimysial-collagen pools. In this study, chemical, thermal and mechanical characteristics were considered and quantified. However, the mechanical function and development of muscle in-vivo could be the main influence on the extracellular collagen characteristics as well as its interactions with non-collagen compounds. Its formation is essential for muscle function.

An analysis of the influence of various tenderising treatments on the tenderness of meat from Polish Holstein-Friesian bulls and the course of changes in collagen

The aim of the study was to analyse the influence of tenderising treatments applied to the carcasses of Polish Holstein-Friesian (PHF) bulls of Black-and-White variety on the process of meat tenderisation and to assess the role of collagen in this process. The research was carried out on m. longissimus thoracis et lumborum. The carcasses were subjected to high-voltage electrical stimulation (ES), conditioning (CD), and both treatments together (ES + CD). The carcasses which were only refrigerated were the control group. The content of collagen in meat, its solubility, the share of the polypeptide subunits α1(I)CB7 and α1(I)CB8 of type I collagen and α1(III)CB5 of type III collagen were also analysed. ES with and without CD significantly accelerated the meat tenderisation and increased collagen solubility. CD always caused the degradation of type I collagen subunits, especially the α1(I)CB7 subunit. However, CD had significantly lesser influence on the rate of meat tenderisation than ES.