Meat tenderization by proteolytic enzymes after osmotic dehydration

The treatment of proteolytic enzymes is one of the popular methods for meat tenderization. In this case, it is very important how to introduce the enzymes into the meat cut. This paper describes meat tenderization by dipping the meat cut in a solution containing proteolytic enzymes after contact-osmotic dehydration. After the dehydration of each piece of meat from culled cow for 18 h by contact-dehydration sheet, each sample was dipped for 3 h in a solution containing papain or proteinases from Aspergillus traditionally used for soysauce production in Japan. It was stored at 3～4°C for 24, 48 and 168 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. The penetration efficiency of the enzyme solution (of around 80%) after the contact-osmotic dehydration seemed to be sufficient. A marked decrease in hardness by texture measurements was observed in the meats treated with proteolytic enzymes and higher sensory scores for tenderness were observed in the meats treated with enzymes as compared with the untreated meat. The papain-treated meat received the highest score in tenderness, but the scores given to juiciness and taste were lower than that of the control. The rapid increases of the fragmentation of myofibrils from the enzyme-treated meat were observed at first 24 h of storage as compared with that of the control. Remarkable degradation of myosin molecule in the myofibrils from the enzyme-treated meats was observed on SDS-PAGE profiles. Considerable degradation of myofibrilar structure especially due to proteolytic removal of Z-lines, was observed among the myofibrils from enzyme-treated meats by electronmicroscopy. The remarkable deformation and disruption of honeycomb-like structure of endomysium were also observed in the meats treated with enzymes. From these results, it was shown that treatment after osmotic dehydration, was effective in tenderizing.     

Tenderization effect of cold-adapted collagenolytic protease MCP-01 on beef meat at low temperature and its mechanism

The enzymes currently used to increase meat tenderness are all mesophilic or thermophilic proteases. This study provides insight into the tenderization effect and the mechanism of a cold-adapted collagenolytic enzyme MCP-01 on beef meat at low temperatures. MCP-01 (10 U of caseinolytic activity) reduced the meat shear force by 23% and increased the relative myofibrillar fragmentation index of the meat by 91.7% at 4 °C, and it also kept the fresh colour and moisture of the meat. Compared to the commercially used tenderizers papain and bromelain, MCP-01 showed a unique tenderization mechanism. MCP-01 had a strong selectivity for degrading collagen at 4 °C, showed a distinct digestion pattern on the myofibrillar proteins, and had a different disruption pattern on the muscle fibres under scanning electron micrograph. These results suggest that the cold-adapted collagenolytic protease MCP-01 may be promising for use as a meat tenderizer at low and moderate temperatures.     

木瓜蛋白酶嫩化牛肉效果的研究

采用TA-XT2i质构仪,研究木瓜蛋白酶处理对牛肉嫩度的影响,对酶活力、pH值、处理温度、处理时间进行实验,并通过L9(34)正交试验选择出最佳嫩化工艺。结果表明：木瓜蛋白酶液的酶活、pH值、处理温度、处理时间对牛肉的持水力、烹饪失水率、剪切力均有显著的影响。木瓜蛋白酶最佳嫩化条件：酶用量20U/g(0.01%)、pH7.0、处理温度37℃、处理时间1.5h;或酶用量40u/g (0.02%)、pH7.0、处理温度20℃、处理时间1.5h。因素的显著性次序为：处理温度＞处理时间＞酶活＞pH值。     

Calcium and potassium content in beef: Influences on tenderness and associations with molecular markers in Nellore cattle

Calcium (Ca) and potassium (K) are essential nutrients in animal nutrition. Furthermore, the Ca content can influence meat tenderness because it is needed by the proteolytic system of calpains and calpastatins, major factors in postmortem tenderization of skeletal muscles. K content, which is needed for muscle contraction, can also affect meat tenderness. This study showed that K positively affects the Warner–Bratzler shear force (WBSF), measured at 14 days of meat aging, which means that higher levels of K are related to lower meat tenderness. Additionally, a significant effect (P ≤ 0.015) of a SNP in the calcium-activated neutral protease 1 (CAPN1) gene on Ca content was observed. Metal content in beef can affect not only nutritional values but also meat quality traits. Part of this effect may be related to variation in specific genes.     

Application of exogenous enzymes to beef muscle of high and low-connective tissue

Exogenous enzymes tenderize meat through proteolysis. Triceps brachii and Supraspinatus were randomly assigned to the seven enzyme treatments, papain, ficin, bromelain, homogenized fresh ginger, Bacillus subtilis protease, and two Aspergillus oryzae proteases or control to determine the extent of tenderization (Warner–Bratzler shear and sensory evaluation) and mode of action (myofibrillar or collagen degradation). Sensory evaluation showed improvement (P < 0.0009) for tenderness and connective tissue component and all except ginger had a lower shear force than the control (P < 0.003). Ginger produced more off-flavor than all other treatments (P < 0.0001). Only papain increased soluble collagen (P < 0.0001). Control samples were only significantly less than ficin for water soluble (P = 0.0002) and A. oryzae concentrate for salt soluble proteins (P = 0.0148). All enzyme treatments can increase tenderness via myofibrillar and collagenous protein degradation with no difference among high and low-connective tissue muscles.     

Tenderization and fragmentation of myofibrillar proteins in bovine longissimus dorsi muscle using proteolytic extract from Sarcodon aspratus

The objective of this study was to examine the Sarcodon aspratus extract including protease how to affect tenderness of the bovine longissimus dorsi muscle. In addition, we investigated myofibrillar protein fragmentation, particularly in myosin, and its influence on meat tenderness. Beef loin chunks were marinated with 0.5 g/100 g, 1 g/100 g, and 2 g/100 g powdered S. aspratus extract, 0.2 g/100 mL papain, and distilled water (control), respectively. Although tenderness of meat is increased by adding S. aspratus extract, differences in meat quality traits, such as muscle pH and meat color, were small and not considered to have practical importance between the control and enzyme-treated samples. Furthermore, the S. aspratus extract influenced the myofibril fragmentation index (MFI) as well as protein solubility. The changes in MFI and protein solubility were due to the myofibrillar protein degradation. Through Western blotting, we found that the S. aspratus extract, as well as papain, caused fragmentation of the myosin heavy chain, but the mushroom extract induced more fragmentations of myofibrillar proteins, and caused more tender meat.     

Antibacterial effects of natural tenderizing enzymes on different strains of Escherichia coli O157:H7 and Listeria monocytogenes on beef

This study determined the efficacy of actinidin and papain on reducing Listeria monocytogenes and three mixed strains of Escherichia coli O157:H7 populations on beef. The average reduction of E. coli O157:H7 was greater than that of L. monocytogenes and higher concentrations of either protease yielded greater reduction in bacterial populations. For instance, actinidin at 700 mg/ml significantly (p ≤ 0.05) reduced the population of L. monocytogenes by 1.49 log cfu/ml meat rinse after 3 h at 25 & 35 °C, and by 1.45 log cfu/ml rinse after 24 h at 5 °C, while the same actinidin concentration significantly reduced the populations of three mixed strains of E. coli O157:H7 by 1.81 log cfu/ml rinse after 3 h at 25 & 35 °C, and 1.94 log cfu/ml rinse after 24 h at 5 °C. These findings suggest that, in addition to improving the sensory attributes of beef, proteolytic enzymes can enhance meat safety when stored at suitable temperatures.     

Effect of blade tenderization and tumbling time on the processing characteristics and tenderness of injected cooked roast beef

The combined effect of blade tenderization (T, NT) and tumbling time (0, 2, 16 h) on quality characteristics of cooked beef roasts processed with 20 or 40% injection level was investigated. Properties of the beef roasts were determined by measuring processing and textural characteristics (shear force, texture profile analysis). Extended tumbling (to 16 h) favorably affected hydration properties and thermal stability, yielding lower cooking loss and purge and higher WHC for beef roasts. It also decreased shear force and hardness of beef samples by 50–60%, but was unable to increase cohesiveness. Blade tenderization prior to injection generally was found to be beneficial for textural characteristics, tended to improve cook yield, but did not influence other hydration properties. An interaction between tenderization and tumbling was observed for shear force. Blade tenderization decreased shear values by 15–20% for roasts tumbled for 0 or 2 h, but did not improve tenderness with extended tumbling.     

重组弹性蛋白酶在猪肉嫩化中的应用

以木瓜蛋白酶作为对照,研究本实验室构建的重组毕赤酵母表达产物即弹性蛋白酶在肉类嫩化方面的应用,测定酶的活力,并对酶的最佳作用条件进行研究,进一步对其在肉类嫩化应用中加酶量、加入方式,肉的处理温度和时间进行优化。实验利用质构仪和嫩度计测定肉的剪切力的变化,按照剪切力与嫩化程度成反相关的规律并结合显微镜观察结果综合判断肉的嫩化程度。结果显示：利用注射法把酶液均匀注射入经过75～80℃水浴加热20～30min 处理的肉样中,加入酶量约20～37mg/mL,处理时间为2.5～6h 时,该重组弹性蛋白酶对肉的嫩化效果较好。     

Intramuscular lipids of Mertolenga-PDO beef, Mertolenga-PDO veal and “Vitela Tradicional do Montado”-PGI veal

Three quality branded meats (n = 68), “Vitela Tradicional do Montado”-PGI veal, Mertolenga-PDO veal and Mertolenga-PDO beef were analysed for cholesterol (HPLC-UV), α-tocopherol (HPLC-FD), fatty acid composition (GC-FID), including conjugated linoleic acid (CLA) isomeric profile (Ag⁺-HPLC), and nutritional value of lipids. All the meats analysed had similar contents (P > 0.05) of cholesterol, α-tocopherol and intramuscular fat. In contrast, the percentage of 18:0 was lower for PGI veal, and that of 18:1 c9 was higher in PDO veal, whilst the percentage of 18:2 n−6 was higher in PDO beef, relative to other two meats. The content of total CLA and the percentage of its t11,c13 isomer were higher, and the n−6/n−3 ratio was lower, in PDO veal, relative to the other two meats. The data suggested that PGI veal has higher variability for most fatty acids than the other two types of meat. Finally, a discriminant analysis was conducted and the three meat types were well discriminated using the meat fatty acid profile as variables.     

MEAT QUALITY ATTRIBUTES OF CHILLED VENISON AND BEEF

ABSTRACT

Meat quality attributes of venison and beef “semimembranosus” muscle stored at ?1.5 C for 4 weeks were compared. Chilled venison had lower L*, a*, b*and chroma compared to beef. Percent expressible water (PEW), shear force and cook loss were lower in venison compared to beef. μ‐Calpain activities at pH 7.4 and 5.5 were higher and the activity of μ + m‐calpain at pH 5.5 (and not at pH 7.4) was lower in venison compared to beef. L*, a*, b*and chroma in meat from both species increased with chilled storage time (P < 0.01); the increase was higher in beef compared to venison. μ‐Calpain activities at pH 7.4 and 5.5 in venison increased in the first week of storage and then declined in the second while it decreased with time in beef at pH 7.4 and followed similar trend as venison at pH 5.5. Activities of μ + m‐calpain at pH 7.4 and 5.5 decreased with chilled storage time in both types of meat. Shear force decreased with storage time, raw meat PEW increased in the first week and cook loss increased for the first 2 weeks of storage and then declined thereafter in both meats. Within the parameters of this study, the table‐eating quality of venison improved and its color deteriorated faster in chilled storage compared to beef implying that the processing inputs required to maximize meat quality of beef may not be suitable for venison and vice versa.

PRACTICAL APPLICATIONS

The following are some of the practical applications of this research: (1) process variables for optimal quality of table beef and venison differ, processors should tailor their process specifically for each specie; (2) venison producers who supply distant markets should consider the rapid rate of tenderization of venison to avoid supplying products with poor texture resulting from over tenderization; (3) the practice of packaging meat under high oxygen environment to enhance color may affect the quality of venison more than other red meats because of the rapid rate of oxidation in venison relative to these meats; (4) the rapid deterioration in the color of venison underscored the need to come up with a way of convincing the consumer to accept the browner color of venison as an inherent characteristic of this meat in order to minimize any bias against the meat because of its color; and (5) the use of fluorogenic substrates for determining calpain activities if further validated in other studies can be used for the online prediction of tenderness early postmortem.

     

Ohmic cooking of whole beef muscle — Evaluation of the impact of a novel rapid ohmic cooking method on product quality

Cylindrical cores of beef semitendinosus (500 g) were cooked in a combined ohmic/convection heating system to low (72 °C, LTLT) and high (95 °C, HTST) target end-point temperatures. A control was also cooked to an end-point temperature of 72 °C at the coldest point. Microbial challenge studies on a model meat matrix confirmed product safety. Hunter L-values showed that ohmically heated meat had significantly (p < 0.05) lighter surface-colours (63.05 (LTLT) and 62.26 (HTST)) relative to the control (56.85). No significant texture differences (p ≥ 0.05) were suggested by Warner–Bratzler peak load values (34.09, 36.37 vs. 35.19 N). Cook loss was significantly (p < 0.05) lower for LTLT samples (29.3%) compared to the other meats (36.3 and 33.8%). Sensory studies largely confirmed these observations. Cook values were lower for LTLT (3.05) while HTST and the control were more comparable (6.09 and 7.71, respectively). These results demonstrate considerable potential for this application of ohmic heating for whole meats.     

Imaging optical diffuse reflectance in beef muscles for tenderness prediction

The objective of this study was to investigate the potential of a novel optical reflectance imaging method to predict beef tenderness. Two-dimensional (2D) optical reflectance in beef muscles induced by a point incident light was acquired. A set of five parameters were extracted from each reflectance image to describe quantitatively the reflectance profiles. Two parameters, q and B, were derived by numerically fitting the equi-intensity contours of the reflectance pattern. Two spatial gradients were calculated along the directions parallel and perpendicular to muscle fibers and total scattering intensity was obtained by excluding the specular reflectance. This method was applied to analyze 2D images of optical diffuse reflectance in 336 beef samples obtained from 14 steers in which large variations in tenderness were generated by altering animal genetics, suspension method and aging time as well as utilizing muscles varying in their inherent tenderness. Tenderness was evaluated using Warner–Bratzler shear force (WBSF). The effects of animal breed, muscle, types of suspension, and aging were investigated and results indicate that the scattering intensity measured at 1-d was correlated (R² = 0.50 at λ = 720 nm) with 10-d WBSF in M. longissimus dorsi muscles; and the q parameters measured at 1-d was correlated (R² = 0.46 at λ = 720 nm) with 10-d WBSF in M. psoas major muscles. These results show analyzing 2D reflectance images of meat surfaces provides valuable information regarding the physical characteristics of meat that are responsible for beef tenderness.     

A comparison of needle-free and needle-injection methods and solutions for enhancement of beef longissimus lumborum muscles

In Experiment 1, beef strip loins (n = 15) were halved and assigned to needle (N) or needle-free (NF) injection enhancement with a phosphate plus salt solution (PS) to determine effects on color, water-binding, and palatability. Pump yields tended (P = 0.08) to be higher for NF injection. Needle-injected steaks were darker (P < 0.05) on day 1 only. The NF treatment had greater instrumental tenderness and intensity of off-flavors but less cooking loss and beef flavor (both P < 0.05). In Experiment 2, strip loins (n = 28) were halved and assigned to one of four treatments: (1) N, or (2) NF injection with PS; (3) N, or (4) NF injection with a calcium lactate solution (CL) to determine effects on water-binding and palatability. Needle-free injection resulted in a greater incidence (P < 0.05) of off-flavors and abnormal texture. The PS solution resulted in greater (P < 0.05) instrumental, myofibrillar, and overall tenderness; greater juiciness; greater incidence of off-flavors and abnormal texture; and less (P < 0.05) connective tissue and cooking losses than CL. The PS and NF combination had the highest pumped yields and least cooking losses (both P < 0.05). Enhancing beef strip loins with PS and NF injection has potential to improve yield, tenderness, and juiciness but harm texture and flavor.     

Meat quality attributes of the Longissimus lumborum muscle of the Kh'ara genotype of llama (Lama glama) reared extensively in northern Chile

Twenty male llama of the Kh'ara genotype, reared extensively in the north of Chile, were slaughtered at ages between 2 and 4 permanent teeth (2 to 3.5 years) and analyses were carried out on the Longissimus lumborum muscle, including composition (moisture, fat, protein, ash, cholesterol, amino acids, fatty acid profile and collagen content) and meat quality parameters (pH, color, water holding capacity and Warner–Bratzler shear-force). Llama meat was characterized by a low cholesterol (39.04 mg/100 g) and intramuscular fat (1.56%) content, a total collagen content of 6.28 mg/g, of which 20.28% was soluble collagen. Amino acid composition and fatty acid profile were similar to those found for beef finished on forage. Llama meat showed a low n − 6/n − 3 (4.69) and hypocholesterolemic/hypercholesterolemic (1.55) ratio and acceptable values of DFA (65.78%). Quality parameters in llama Longissimus muscle were within the ranges reported for more traditional meats such as beef and lamb.     

菠萝汁对牛肉的嫩化效果研究

以菠萝汁和牛肉为原料,研究菠萝汁中菠萝蛋白酶对牛肉的嫩化作用,得到了嫩化的最佳工艺：菠萝汁浓度6%、时间60min、温度50℃、pH7.0。在此条件下,牛肉剪切力可降低50% 左右。对菠萝汁、生姜汁、木瓜蛋白酶嫩化产品与对照组进行了风味、色泽、剪切力的对比,结果表明：菠萝汁较生姜汁能够显著(p ≤ 0.05)提高产品的风味,相比木瓜蛋白酶及对照组其风味也有不同程度提高;菠萝汁、生姜汁、木瓜蛋白酶都能极显著(p ≤ 0.01)的提高产品的嫩度,而三种嫩化产品之间嫩度没有显著差异;用菠萝汁嫩化牛肉,在牛肉腌制后,其色度的b 值和a/b 值相对于对照组有极显著(p ≤ 0.01)提高,而在煮制后,只有b 值和对照组有显著(p ≤ 0.05)差异,而a/b 值无显著差异,表明用菠萝汁嫩化牛肉不会对产品的色泽造成不良影响。     

Variation in bull beef quality due to ultimate muscle pH is correlated to endopeptidase and small heat shock protein levels

This study set out to determine if ultimate pH (pH_u) affected the performance of intracellular small heat shock protein and endopeptidase dynamics in muscle during beef ageing. Longissimus dorsi muscles from 39 Angus or Limousin × Angus bulls were examined to see if pH_u achieved at 22 h post mortem (rigor) affected tenderness and water holding capacity of beef. Samples were segregated into three pH_u groups termed high (pH > 6.3), intermediate (5.7 < pH < 6.3) and low (pH < 5.7) pH_u beef. More than 30% of bull beef did not achieve acceptable tenderness at 8 days post mortem with this ageing regime. No significant differences in calpain or cathepsin enzyme levels due to meat pH were observed until after 22 h post mortem, but low pH_u beef had elevated caspase 3/7 activity soon after slaughter. At 22 h post mortem, greater levels of μ-calpain enzyme were found in the high and intermediate pH_u beef and cathepsin B levels were superior in the low pH_u beef after 2 days post mortem. Different rates of desmin and troponin T protein degradation were also observed in aged bull beef. Both proteins were degraded within 6 h post mortem for high pH_u beef, but took >3 days post mortem for intermediate pH_u beef. High levels of alpha β-crystallin (aβC) at 22 h post mortem coincided with delayed muscle protein degradation for low pH_u beef. Our results support the hypothesis that aβC shields myofibrils and buffers against endopeptidase degradation of beef structure during ageing.     

Biochemical and sensorial evaluation of intact and boned broiler breast meat tenderness during ageing

Meat tenderness is the main characteristic demanded by consumers and is affected by rigor mortis development and proteolysis activities, both of which occur during carcass refrigeration. In this work, we demonstrate that broiler breast fillet tenderness can be further increased and its extension depends on whether or not meat is excised from the carcass. Post-harvest samples taken from 0 to 72 h after slaughtering and kept refrigerated at 2 ± 2 °C were evaluated for tenderness by myofibrillar fragmentation index determination, shear force analysis and sensorial testing. The 24 h post-harvested intact samples were 30.6% more tender than excised samples and 41.7% more tender than control samples (p ? 0.05). The myofibrillar fragments index was 13.2% higher in intact samples than in deboned fillet (p ? 0.05) and a sensory test showed that the 24 h intact samples were of major acceptability. Our results demonstrated that tenderness was best achieved with intact breast fillet samples stored at 2 ± 2 °C for 24 h.     

新型牛肉嫩化技术研究进展

嫩度是评价牛肉品质的关键指标,直接影响消费者的购买意向。因此,如何改善牛肉的嫩度一直是肉品研究领域的重点。随着科学技术的发展,新型肉类嫩化技术不断涌现,目前在牛肉生产中新引入的智能拉伸、超声波和脉冲电场等技术在牛肉生产领域得到广泛关注。基于近期的研究成果,该文详细深入地对上述3种技术的作用机制、嫩化效果及应用前景进行了综述,发现高强度(10~1 000 W/cm^2)低频率(20~100 k Hz)超声波在改善牛肉嫩度方面效果显著,是一种有效的牛肉嫩化技术,多种肉类嫩化技术的复合应用也是未来肉类产业发展的趋势。     

Mutations in calpastatin and μ-calpain are associated with meat tenderness,flavor and juiciness in Hanwoo (Korean cattle): Molecular modeling of the effects of substitutions in the calpastatin/μ-calpain complex

The objective of this study was to evaluate the effects of seven single nucleotide polymorphisms (SNPs) in Calpain 1 and Calpastatin genes previously associated with meat tenderness attributes in other cattle breeds in Korean Hanwoo cattle. The Hanwoo resource population was used to study association of 7 SNPs with beef tenderness, flavor, juiciness, intramuscular fat and shear force. In this association study, CAST:c.182A > G (+ 0.14, P = 0.04) and CAST:c.1985G > C (− 0.12, P = 0.02) had significant effects on juiciness, but no effects on other traits. In contrast, CAPN1:c.1589G > A was associated with meat tenderness (P = 0.01) and juiciness (P = 0.04). The CAPN1:c.1589G > A (Val530Ile) SNP marker displayed significant effect on the meat tenderness score which is strongly supported by molecular modeling of the CAPN1:c.1589G > A (Val530Ile) variant that inhibits CAST protein from binding more strongly than the wild-type protein, which may explain its effect on meat tenderness.