Proteins degradation value in cured meat product made from M. Cutaneous-omo brachialis muscle of bovine

We analyzed differences in some physicochemical parameters of proteins in shoulder rose (M. Cutaneous-omo brachialis) muscle as a result of beef processing to produce pastirma. Samples from processed muscles showed significantly increased concentrations of extracted proteins, especially of H₂O P-ex and Guba-Straub–adenosine triphosphate solution (P < 0.01), as a result of the salting–curing process. The salt-curing process was likely to have an important effect on the extractability of muscle proteins such as myosin heavy chain (MHC) and water-soluble proteins, possibly as a result of releasing some proteins from each other and cleaving the structures between certain proteins. The fluorescence intensities of processed samples were higher than those of the control samples at all guanidine hydrochloride concentrations. The hydrophobicity also increased on account of new compounds that were created during the pastirma-making process. Since the process of making pastirma lasts about 4 weeks (drying), the metmyoglobin content was greatly increased in pastirma samples compared with the unprocessed samples (by as much as 57 %). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis results conceived that during processing of pastirma products, MHC and other muscle proteins degraded into polypeptides with smaller molecular weight lower than 15-kDa. The results of this study demonstrated that meat processing promoted the enzymatic digestion of some proteins, and the differences in composition between the control and pastirma samples were thus likely to be owing to protein degradation. The traditional pastirma-making process hence has no negative impact on the structure of the muscle and produces a firmer-textured.     

Effect of Existence of Exogenous Protein on Physicochemical Properties of Heat- and Transglutaminase-induced Bovine Collagen-peptide Gel

ABSTRACT: The combined influence of preheat treatment, mixing with various proteins, and the addition of microbial transglutaminase (MTGase) on the physicochemical properties of bovine collagen-peptide (BCP) gel was investigated. The preheat treatment and the mixing with various proteins contributed to the enhancement of the gel strength and polymerization of BCP. The gel made with 0.1% MTGase showed the highest breaking strength. The melting point of the preheated BCP gel was higher than that of the unheated one ( P < 0.05). The gel made with a combination of preheated BCP-casein or preheated BCP-soybean protein showed a higher melting point than that made with preheated BCP alone ( P < 0.05). The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern of the mixture of preheated BCP with casein or soybean protein showed that the protein bands with relatively low molecular weights disappeared and the bands with relatively high molecular weights increased. Observation by a scanning electron microscope revealed that the preheated BCP gel prepared with MTGase had a well-defined cross-linked network and showed some clumps of aggregated proteins. These results show that preheating, mixing with other proteins and MTGase treatment, are effective ways to make BCP a fine biopolymer.     

Effect of microbial transglutaminase on the natural actomyosin cross-linking in chicken and beef

The objective of this research was to investigate the difference between chicken and beef in the interaction of actomyosin (myosin B) with microbial transglutaminase (MTG). The gel strength of myosin B was improved in both species and was significantly greater in beef than in chicken (P < 0.01). The degree of protein viscosity and the ε(γ-glutamyl)lysine (G–L) content were significantly higher in beef than in chicken (P < 0.01). Myosin heavy chain (MHC) bands visualized by SDS–PAGE revealed that the same proteins in various meat species vary in their size and structure. Scanning electron microscope images (SEMI) revealed that myosin B in both species was polymerized, and formed multi-projection structures of G–L; surprisingly, more of these structures were found in beef than in chicken. It is possible that the proteins in chicken are folded into a strand shape that tightly encases a considerable number of glutamine and lysine residues, whereas MTG substrate cannot couple glutamine and lysine. This suggests that the reactivity of MTG is dependent on the residual amino acids present on the surface of myosin B in meat. Some protein components (peptides with long reiterated methylene groups attached) joined by disulfide bonds (cysteine) in chicken samples were inhibitory and reduced MTG activity. SEMI also suggested that all MTG-dependent mega-structures of protein molecules generated in chicken and beef may vary greatly in size, configuration and complexity after treatment with MTG. We concluded that the optimal cross-links in myosin B induced by MTG are heterogeneous in chicken and beef.     

Dependence of microbial transglutaminase on meat type in myofibrillar proteins cross-linking

The objectives of this study were to determine the factors that cause differences in the improvements of gel strength and ε(γ-glutamyl)lysine (G-L) content in chicken and beef (Japanese black cattle) myofibrillar proteins after adding microbial transglutaminase (MTG). As the amount of MTG added increased, the breaking strength increased progressively (p < 0.01) in chicken and beef samples, with the exception of chicken samples treated at 40 °C. The values of elasticity in the chicken samples were lower than those of the beef samples (p < 0.01). Surprisingly, the elasticity level, ε(γ-glutamyl)lysine contents and myosin heavy chain (MHC) band sizes of chicken and beef at all levels of MTG were significantly different (p < 0.01). The results of this study suggest that MTG activity was affected by MTG inhibitors; that MTG develops the texture of myofibrils differently in different species. However, the activity is limited and inconstant among meat proteins, as suggested by the data collected from the chicken samples. As a result, when the transferable amino acid residues are depleted (cross-linked) by MTG activity, the function of MTG will be insignificant. The correlation between MTG and different sources of meat protein is quite unstable but it is strong, which was observed when chicken and beef responded differently to MTG because their chemical and physiological properties were different. The remarkable rate of formation of cross-linked proteins and the discrepancy between the expected and observed amount of dipeptide raises the possibility that there are enzymes capable of reversing the reaction induced by transglutaminase in chicken and beef myofibrils. In summary, our results suggest that access of MTG to chicken and beef myofibrils is different because it depends on physiological (muscles and their fibre types), biological (substrates) and biochemical (inhibitors and amino acids) variables.     

Effects of a humidity-stabilizing sheet on the color and K value of beef stored at cold temperatures

The effects of a humidity-stabilizing sheet containing glycerol, on the color and K value of beef stored at cold temperatures were investigated in this study. A drip-absorbing sheet seems to be effective for the preservation of meat quality, while a humidity-stabilizing sheet containing glycerol prevents the increase of metmyoglobin in cold stored beef. Maintaining samples wrapped in humidity-stabilizing sheets containing glycerol at low temperature for 7days was a functional method for conserving the concentration of inosine monophosphate. Beef samples wrapped in sheets containing glycerol had lower K values than samples wrapped in sheets not containing glycerol. When the surface of the meat starts to desiccate, the humidity-stabilizing sheet releases moisture that has been absorbed from the beef in the early stages of storage. Thus, glycerol could potentially play a role as a humidity-stabilizing controller and color preservative. This research suggests that a humidity-stabilizing sheet containing glycerol is a useful moisture controller and prevents deterioration of meat quality, discoloration, and desiccation.     

Differentiation in improvements of gel strength in chicken and beef sausages induced by transglutaminase

This research investigated the improvement in the texture of chicken and beef sausages induced by using microbial transglutaminase (MTG). The ε-(γ-glutamyl)lysine (G-L) content and the extractability of myofibrillar proteins from these sausages were also investigated. Treatment with MTG significantly affected the breaking strength score in both meat types, especially for beef cooked at 80°C (p<0.001). The protein concentration of both meat types treated with MTG and extracted in water-soluble protein solution (WSP) was slightly decreased; compared with a significant decrease (p<0.003) in samples extracted in Guba-Straub-ATP solution (GS-ATP). The variation in protein extractability of both meat types could lead to some considerations of the mechanisms and the high affinity reaction between MTG and myosin heavy chain (MHC). SDS-PAGE analysis revealed significant changes in the density of the bands after adding MTG, especially for the beef samples. The G-L content in the presence of MTG was double that in control samples of both meat types. The amount of crosslinking in chicken and beef meat was different and found to be reasonable. Collectively, this suggests that the binding ability of myofibrillar proteins with MTG is strong and dominated by MHC. There was a unique reaction among MHC proteins with MTG molecules considered as a very advantageous reaction. This leads us to suggest that the functional properties of MTG make it a beneficial protein-binding agent, positively helping the functionality of proteins to improve the texture and gelation of meat products that are treated mechanically, such as sausages. Some variation in gel improvement level between chicken and beef sausages was observed; this resulted from the variation in meat proteins in response to MTG, as well as to the original glutamyl and lysine contents.     

Impact of transglutaminase on the textural, physicochemical, and structural properties of chicken skeletal, smooth, and cardiac muscles

This study examined the effects of microbial transglutaminase (MTG; 3.1 mg/ml) on chicken skeletal, smooth, and cardiac muscles; the meat containing the different muscle types was shaped into sausages and treated at 40 °C and/or 78 °C for 30 min. Although the three muscle types were obtained from the same bird, the effects of MTG addition were not uniform. All the muscle types showed a significant increase in the breaking strength (P < 0.01), but skeletal muscle exhibited the maximum increase. All samples showed a decrease in the fluorescence intensity and a significant reduction in the concentration of proteins that were extracted in a high ionic strength solution (P < 0.05). Scanning electron microscopy images and histological studies revealed that different muscle types had different physical structures and frameworks after MTG treatment, which is a reflection of the differences in the reaction specificity of MTG with different muscle proteins. Histological studies revealed that the reactions of MTG with meat proteins are both exogenous and endogenous. Cooking loss data suggested that MTG did not have any negative effect on water retention during cooking. MTG appears to be a functional and contributive substance since the results suggest that MTG can function on all muscle types that are mechanically processed for different industrial applications. MTG aggregates muscle proteins in different ways that improve their organoleptic properties such as texture, appearance, and water retention.     

A review of meat protein hydrolysates and hypertension

We tested the hypothesis that meat is a source of peptides that are effective at preventing and reducing chronic lifestyle-related diseases (CLSRDs) such as hypertension. This analysis reflects the importance of empowering hypertensive people in quality versus quantity of life issues, and in offering nutritional treatment options rather than medical alternatives. For both hypertensive and normotensive individuals, chemically based medications may have harmful side effects. Functional food rich in antioxidant vitamins, and proteins or biologically active peptides, can lower blood pressure in persons with essential hypertension, possibly by preventing an underlying cause of the condition. Deficiency in consumption of crucial nutrients such as proteins from meat origins, along with abnormalities in carbohydrate and fat metabolism, may underlie the etiology of the clinical course of hypertension. Food derived from meat rich in nutrients may provide physiologically functional peptides, as well as improve digestion, and the metabolism of carbohydrate and fats, thus lowering blood pressure, and normalizing associated biochemical and histopathological changes.     

Identification of pro-drug type ACE inhibitory peptide sourced from porcine myosin B: Evaluation of its antihypertensive effects in vivo

This study aimed to identify a novel angiotensin I-converting enzyme (ACE) inhibitory peptide from porcine skeletal myosin B. Proteins were hydrolyzed with pepsin and the hydrolysates were then subjected to various types of chromatography to isolate the active peptides. The 50% inhibitory concentrations of Lys–Arg–Val–Ile–Gln–Try (M6 a novel peptide) and Val–Lys–Ala–Gly–Phe (A5, a peptide discovered by Ukeda et al. (1991)) were 6.1 and 20.3 μM, respectively. As a result of a homology search, it was determined that the M6 peptide originated from myosin and peptide A5 was of actin origin. M6 is a novel ACE inhibitory peptide, whose activity was shown to be the strongest amongst the previously published myosin-originated peptides. Kinetic evaluations showed that both peptides are competitive inhibitors of ACE. Based on their activity against ACE, M6 was classified as a pro-drug conformer and A5 was classified as a substrate conformer. When both peptides were administered orally to spontaneously hypertensive rats at doses of 10 mg/kg, temporal hypertension was observed after 6 h. This study suggests that M6 and A5 are peptides that may serve several purposes. Based on their remarkable antihypertensive activity, we suggest that M6 and A5 may have potential applications as functional food, which could be used as nutraceutical compounds.     

Evaluation of the performance of osmotic dehydration sheets on freshness parameters in cold-stored beef biceps femoris muscle

This study aimed to evaluate the effects of osmotic dehydration sheet (ODS) packaging on the quality parameters of beef biceps femoris muscle samples stored at 4 °C for 0, 1, 3 and 7 days. Quality indices such as Hunter color values (L^∗, a^∗ and b^∗, the percentage of metmyoglobin (Met-Mb%), K value (freshness index), and the contents of adenosine triphosphate (ATP)-related compounds (ARCs), thiobarbituric acid reactive substances (TBA-RS) and volatile basic nitrogen (VBN) were measured. ODS gave lower a^∗ and b^∗ values and lower Met-Mb% compared with control samples wrapped in polyvinylidene chloride film (PVDCF) (P < 0.01), but had no effect on L^∗ (P < 0.01). As a result, with higher levels of osmotic dehydration produced by the ODS, the percentage of weight loss and the total contents of ARCs and inosine monophosphate of the samples also increased (P < 0.05). The K values of ODS samples were also significantly lower than PVDCF-wrapped samples (P < 0.05). Low performance ODS wrapping reduced the TBA-RS values below those found with PVDCF and high performance ODS processing (P < 0.01). Moreover, the use of ODS had no effect on VBN values. Thus, although the bright red of beef samples changed to a dark purple color and the weights of samples decreased, the ODS approach has potential as a tool for decreasing the deterioration of other quality indices such as Met-Mb%, TBA-RS, ARCs, K values and the VBN content of cold-stored beef.