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BACKGROUND Texture softening is always a problem during chilling of grass carp fillets. To solve this problem and provide for better quality of flesh, understanding the mechanism of softening is necessary. Gelatinolytic proteinases are suspected to play an essential role in the disintegration of collagen in softening of fish flesh. In the present study, the types and contribution of gelatinolytic proteinases in chilled fillets were investigated. RESULTS: Four active bands (G1, 250 kDa; G2, 68 kDa; G3, 66 kDa; G4, 29 kDa) of gelatinolytic proteinases were identified in grass carp fillets by gelatin zymography. The effect of inhibitors and metal ions revealed that G1 was possibly a serine proteinase, G2 and G3 were calcium‐dependent metalloproteinases and G4 was a cysteine proteinase. The effect of the inhibitors phenylmethanesulfonyl fluoride (PMSF), l‐3‐carboxy‐trans‐2,3‐epoxy‐propionyl‐l‐leucine‐4‐guanidinobutylamide (E‐64) and 1,10‐phenanthroline (Phen) on chilled fillets revealed that gelatinolytic proteinase activities were significantly suppressed. Collagen solubility indicated that metalloproteinase and serine proteinase played critical roles in collagen breakdown during the first 3 days, and cysteine proteinase revealed its effect after 3 days. Meanwhile, during chilled storage for 11 days, the final values of shear force increased 19.68% and 24.33% in PMSF and E‐64 treatments when compared to control fillets respectively, whereas the increase after Phen treatment was 49.89%. CONCLUSION: Our study concluded that the disintegration of collagen in post‐mortem softening of grass carp fillets was mainly mediated by metalloproteinase and to a lesser extent by serine proteinase and cysteine proteinase. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: High variation in meat quality has been reported between animals and within muscles of same animals. An understanding of these variations is a pivotal step to design strategies for better utilization of such meat while producing high quality meat to consumers. The current study was aimed to unravel biochemical and physico-chemical profile of sheep hind limb. Methods: The sheep hind limb was procured from traditionally slaughtered sheep immediately after exsanguination. The Vastus lateralis (VL), Gluteo biceps femoris (GBF), Gluteomedius (GM), Longissimus thoracis et lumborum (LTL), Psoas major (PM) and Semitendinosus (ST) muscles were separated from hot boned carcass of sheep. Each hot boned muscle was cut and analysed for biochemical and physico-chemical characteristics. Result: There was significant (p<0.05) variation in water holding capacity, protein extractability (Sarcoplasmic, myofibrillar and total), collagen content, collagen solubility and instrumental colour value among different skeletal muscles studied. Non-significant (p>0.05) variations were found in parameters like pH, drip loss, myofibrillar fragmentation index, muscle fibre diameter and Warner Bratzler shear force values. The Gluteo biceps femoris muscle was found to have higher myoglobin; myofibrillar fragmentation index and Warner Bratzler shear force values with lowest protein extractability values. The collagen content in the Gluteo biceps femoris was significantly (p<0.05) higher with lowest collagen solubility (15.32%) as compared to other muscles. [ABSTRACT FROM AUTHOR]

Summary: The aim of the present study was to investigate the underlying mechanisms of softening texture in chilled grass carp filletsunderpinning collagen solubility, gelatinolytic proteinase activity and physicochemical parameters. Acid‐soluble collagen (ASC) and heat soluble collagen (HSC) increased markedly, while a significant decline was detected in total collagen and insoluble collagen (ISC) during the first 3 days of storage, coinciding with a loss of shear force and water‐holding capacity (WHC) (P < 0.05). Moreover, the activity of gelatinolytic proteinases was gradually activated and reached the peak at day 3 (P < 0.05). Pearson coefficient analysis showed that gelatinolytic proteinase activity revealed a significant correlation with collagen solubility. Total collagen, ASC, ISC and HSC were significantly correlated with shear force and WHC. Our study clarified that the increase of collagen solubility by gelatinolytic proteinases played an important role for texture softening in the early stage of chilled grass carp fillets. [ABSTRACT FROM AUTHOR]

The combination of proper temperature and time duration in sous-vide cooking could provide good water-holding capacity, color parameters, and tender cooked meat. In this study, goat muscles gluteus medius (GM) and biceps femoris (BF) treated with single-stage sous-vide (cooked at 60 °C, 65 °C, 70 °C) and two-stage sous-vide (cooked at 45 and 60 °C, 45 and 65 °C, 45 and 70 °C) methods for 6 h and 12 h were compared. Cooking loss decreased by 5–10% for GM and 10–13% for BF after 6 h of heat treatment with two-stage sous-vide likely due to high sarcoplasmic solubility. Cooking time and temperature combination in two-stage sous-vide contributed to better a* values for both GM and BF, with higher values recorded for 6 h at 45 and 60 °C. Significant reduction of toughness was successfully achieved using stepped cooking temperatures compared with sous-vide cooking at a single temperature. The lowest shear force values were achieved at a combined temperature of 45 and 60 °C with only 6 h of cooking duration (GM 28 N; BF 40 N) likely from desmin degradation. However, the tenderness effect of single-stage sous-vide was seen after collagen solubility was maximized in prolonged cooking at 70 °C, but other quality features such as redness values and water content had recorded the lowest values. [ABSTRACT FROM AUTHOR]

Intramuscular collagen may affect the value of meat by limiting its tenderness and cooking convenience. Production factors such as age of animal at slaughter, the use of steroids and beta-adrenergic agonists as growth promotants, and cattle breed may affect the contribution of collagen to beef quality. Recent research has indicated that concentrations of the mature collagen cross-link pyridinoline (PYR) are positively correlated with Warner-Bratzler shear force (WBSF) and animal age at slaughter, while contribution of the concentration of a second mature collagen cross-link Ehrlich's Chromogen (EC) to beef toughness declines with cattle age. Cattle breed influences total collagen content of muscle due to differing rates of maturation among breeds. Growth promoting technologies do not appear to affect collagen solubility, but do influence PYR and EC densities and concentrations in some beef muscles. Concentrations of PYR and EC do not account for all the variation in collagen heat solubility in beef muscles, nor do advanced glycation end products given the relative immaturity of cattle at slaughter. In light of this, other collagen cross-links such as heat-stable divalent cross-links may warrant reconsideration with regard to their contribution to cooked beef toughness. [ABSTRACT FROM AUTHOR]

Most scientific studies are dedicated to the possibility of preparing beef for consumption under industrial conditions. Few publications are devoted to the issue of collagen thermohydrolysis in conditions available to the consumer. This study has analyzed the effect of small values of water vapor pressure on major culinary indices and chemical components of the longissimus lumborum muscle obtained from bulls with different growth rates. The experiment involved 48 animals. On the basis of the gain during the fattening time, the animals were divided into a low growth intensity group, with a daily body weight gain of =900 g, and a high growth intensity group with a daily gain of >900 g/day. A part of the samples of the longissimus lumborum muscle (control) was thermally treated in a water bath at 75°C. Another part was heat treated in a pressure-pot at 150°C, at a pressure of 0.1 MPa. The next part of samples was subjected to the same temperature, but the pressure was 0.2 MPa. The obtained results indicate that the values of the studied indices were largely affected by thermal processing parameters rather than the animals' growth rate. The highest contents of total protein and water-soluble collagen were obtained in the case of a temperature of 150°C and the highest pressure (0.2 MPa). Water vapor with increased temperature and pressure also created favorable conditions for obtaining better meat tenderness and more favorable values of the water holding capacity. The latter characteristic appeared to be strongly connected with an increasing amount of water-soluble collagen, which was confirmed by relatively high values of the correlation coefficient between these characteristics. A strong positive correlation was also shown between thermal drip and the total collagen content in meat. [ABSTRACT FROM AUTHOR]

The objective of the current study was to include tenderizing agents in the formulation of camel meat burger patties to improve the physico-chemical and sensory characteristics of the product. Camel meat burger patties were processed with addition of ginger extract (7%), papain (0.01%) and mixture of ginger extract (5%) and papain (0.005%) in addition to control. Addition of ginger, papain and their mixture resulted in significant ( P < 0.05) increase of the collagen solubility and sensory scores (juiciness, tenderness and overall acceptability) with significant ( P < 0.05) reduction of the shear force values. Ginger extract resulted in extensive fragmentation of myofibrils; however, papain extract caused noticeable destructive effect on connective tissue. Moreover, ginger and papain resulted in improvement of the lipid stability of treated burger patties during storage. Therefore, addition of ginger extract and papain powder during formulation of camel burger patties can improve their physico-chemical and sensory properties. [ABSTRACT FROM AUTHOR]

The effect of radiation processing (0, 2.5, 5 and 10 kGy) on the tenderness of three types of popularly consumed meat in India namely chicken, lamb and buffalo was investigated. In irradiated meat samples dose dependant reduction in water holding capacity, cooking yield and shear force was observed. Reduction in shear force upon radiation processing was more pronounced in buffalo meat. Protein and collagen solubility as well as TCA soluble protein content increased on irradiation. Radiation processing of meat samples resulted in some change in colour of meat. Results suggested that irradiation leads to dose dependant tenderization of meat. Radiation processing of meat at a dose of 2.5 kGy improved its texture and had acceptable odour. [ABSTRACT FROM AUTHOR]

Abstract: The tenderness characteristics of 15 primal cuts of beef of three different age groups were assessed, and the most reliable cut to predict carcass tenderness was determined. Fifteen wholesale cuts from each age group, representing the full variation in fatness, were aged, cooked and underwent sensory evaluation, shear force resistance and proximate analysis. Collagen content and solubility was determined. Percentage fat was used as a covariant during statistical analyses. Tenderness, residue and collagen solubility of all cuts decreased significantly with animal age. Collagen solubility was the largest discriminant between the three age groups, while animal age had no significant effect on collagen content. Tenderness of primal cuts from the same carcass varied considerably, with collagen content and shear force resistance as the largest discriminants between the cuts. Cuts most representative of total carcass tenderness were M. vastus lateralis, M. semimembranosus, M. gluteobiceps, M. semitendinosus and M. triceps brachii caput longum. [ABSTRACT FROM AUTHOR]

Collagen is the main component of the extra-cellular matrix and has been utilised for numerous clinical applications in many forms and products. However, since collagen remains a natural animal-derived biopolymer, variation between batches should be addressed and minimised to ensure reproducibility of the fabrication process. Recently, electro-spinning of collagen has been introduced as a leading technique for the production of bio-mimetic nano-scale scaffolds for tissue-engineering applications. However, no protocols are available that would allow comparisons of the quality of different collagen raw materials prior to the electro-spinning process. In order to bridge this gap we assessed the solubility of various freeze-dried collagens in 0.5 M acetic acid and analysed the solved collagen by gel electrophoresis. We show that raw material of limited solubility in acetic acid will not render high quality electro-spun nano-fibres using hexafluoropropanol. In particular, insoluble collagen directly failed to produce nano-fibres, collagen of reduced solubility produced fused nano-fibres with limited inter-nano-fibre space, whilst purified type-I collagen of high solubility produced smooth, reproducible nano-fibres. Gel electrophoresis confirmed the amount of solubility, as well as qualitative differences in terms of collagen cross-links and collagen types. We recommend this simple and fast step to save costs and to enhance control over the electro-spinning process of collagen. Furthermore, we believe that the solubility test should be introduced prior to any collagenous matrix preparation in order to ensure reproducibility and accuracy. [ABSTRACT FROM AUTHOR]

Abstract: Connective tissue of three porcine muscles (M. infraspinatus, IS; M. longissimus dorsi, LD; M. semimembranosus, SM) from 27 animals [populations A (n =13, reared in Ireland) and B (n =14, reared in Finland)] was studied by measuring the collagen content, collagen solubility and thermal shrinkage temperature of the connective tissue. Colour and pH were also determined. Collagen solubility was highest in IS (p <0.05) and lowest in SM (p <0.05) although no difference between LD and SM was found in population B. The onset and peak temperatures of thermal shrinkage (T o and T p) were highest in IS (p <0.05). The lowest T o and T p were found in SM from population B whereas no differences were seen between LD and SM muscles in population A. It was concluded that the thermal stability of the connective tissue in the three porcine muscles differ. IS, as a dark muscle has high thermal shrinkage temperatures and high collagen solubilities in comparison to the lighter LD and SM muscles which have lower thermal shrinkage temperatures and collagen solubilities. Collagen contents were highest in IS and lowest in LD. [Copyright &y& Elsevier]

Abstract: The effect of cooking temperature (80–100°C) and time (30–60min) on collagen solubility of Semimembranosus muscle in carabeef were investigated. The pH, cooking loss, shear force value, collagen content, collagen solubility, sensory evaluation and histological observations of water bath cooked and pressure cooked Semimembranosus meat samples were measured. Increase in pH, cooking loss, collagen solubility and tenderness scores with decrease in shear force value and collagen content was observed with increases in cooking temperature and time. However, no statistical difference was observed for shear force values, collagen solubility values and tenderness scores in pressure cooked meat and meat cooked in a water bath at 100°C for 45min, inferring that cooking of buffalo meat at 100°C for 45min improved collagen solubility and tenderness to the same extent as that due to pressure cooking. [Copyright &y& Elsevier]

Effects of preslaughter nutritional condition on intramuscular collagen characteristics were studied, in order to clarify the potential of intensive feeding to aged animals in improving meat tenderness. Ten castrated male goats were assigned into one of two groups: one group was allowed ad libitum access to a concentrate diet (total digestible nutrients 70%, crude protein 15%) and Italian ryegrass hay (ADLIB-group), and the other group was fed a restricted amount of their diet (concentrate diet 0.5% of bodyweight/day; hay 1.5% of bodyweight/day) to maintain their bodyweight (MAIN-group). After 3 months of the experimental period, goats were slaughtered and meat samples were obtained immediately. Goats in ADLIB-group had lower total and insoluble collagen concentrations, higher fat concentrations and collagen solubility than those in MAIN-group, but soluble collagen concentrations of muscles were similar for both groups. Goats in ADLIB-group had lower pyridinoline concentrations than those in MAIN-group, in all muscles, but the differences of pyridinoline concentration between the groups were not statistically significant. Warner-Bratzler shear force values of Longissimus and Biceps femoris muscles were lower in ADLIB-group than in MAIN-group. The increase of meat tenderness by preslaughter intensive feeding seemed to be associated with the increase in intramuscular fat deposition and high collagen solubility, and pyridinoline cross-link appeared to be one of the factors related to collagen solubility. [ABSTRACT FROM AUTHOR]

Bovine semitendinosus (ST) muscles aged for 5 and 12 days at 4 °C were roasted at 170 °C to internal temperatures of 50, 60, 70, 80 and 90 °C. Microstructural changes in meat were evaluated using a scanning electron microscope (SEM). Texture profile analysis (TPA) and measurements of the shear force values of samples were conducted using a texture analyser. The cooking losses and quantity of total and soluble collagen were also estimated. The structure of intramuscular connective tissue and myofibrillar structure of meat after 5 days of ageing was very regular. In 12-day-aged samples fibrous and myofibrillar structures were less distinct, damages of endomysium tubes appeared and fibres of perimysium were swelled. Ageing of ST muscle for 12 days caused a two-fold increase in the quantity of soluble collagen and a two-fold decrease in the value of TPA parameters—hardness and chewiness, as compared to 5-day-aged samples. The decrease in fibre diameter and sarcomere length during roasting started at 60 °C in 5-day-aged meat and at 50 °C in 12-day-aged samples. The shear force values measured after roasting were lower for 12-day-aged meat than for 5-day-aged samples. The quantity of soluble collagen in roasted meat increased at an internal temperature of 80 °C. At a higher temperature of meat this variable depended on the degree of meat ageing. The cooking losses during roasting of meat were about 3% lower for 12-day-aged than for 5-day-aged samples. In the examined range of internal temperature of meat the cooking losses and the sarcomere length were negatively correlated. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]