Sarcoplasmic Protein Solubility Research Articles

Tenderness and physicochemical characteristics of meat treated by recombinant bromelain of MD2 pineapple from a codon-optimized synthetic gene

Bromelain is a complex of cysteine proteases from pineapple (Ananas comosus) which was widely used in meat tenderizers. Earlier, using a synthetic optimized gene approach, recombinant bromelain of MD2-pineapple (MD2-MBro) was successfully produced in a fully soluble form. Nevertheless, the use of MD2-MBro to tenderize the meat has never been examined. Indeed, no report on the meat tenderization activity using recombinant bromelain was found. The aim of the current study is to determine the effect of MD2-MBro on meat tenderness and its physicochemical properties. To address this, MD2-MBro was over-expressed in Escherichia coli BL21 CodonPlus(DE3), followed by purification using a single step of Ni-NTA affinity chromatography. Fresh lamb shoulder meat from a local market in Kota Kinabalu, Sabah, Malaysia, was then treated with MD2-MBro at the concentration of 0 (B0), 0.01 (B1), 0.05 (B2), and 0.1% (B3). The meat tenderness was measured using Warner-Bratzler shear forces, indicating that the addition of MD2-MBro had significantly (P < 0.01) reduced the shear force value from 8.80kg/cm2 to the range of 6.01 to 6.92 kg/cm2, which falls under the category of tender. The ability of MD2-MBro to tenderize meat might be related to its ability to degrade myofibril protein, as demonstrated by the formation of a clear zone under an agar plate system and scanning electron microscopy. Besides, the total protein or sarcoplasmic protein solubility was significantly enhanced by the MD2-MBro treatments, along with soluble peptides, free amino acids, collagen content, and collagen solubility, which indicated the improvement in meat protein digestibility. Other physicochemical properties (color, pH, water-holding capacity, and cooking loss) of the meat were affected by MD2-MBro treatments yet remained in the normal range. Altogether, while MD2-MBro consisted of only a single cysteine protease enzyme, this protein can tenderize meat and increase protein digestibility, with acceptable changes in the overall physicochemical properties.
 Keywords: bromelain, cysteine protease, meat tenderizer, recombinant protein, pineapple

Dietary guanidinoacetic acid supplementation improves water holding capacity and lowers free amino acid concentration of fresh meat in finishing pigs fed with various dietary protein levels.

The current study was carried out to detect the effect of dietary guanidinoacetic acid (GAA) supplementation on carcass characteristics and meat quality in finishing pigs fed different dietary crude protein (CP) levels. Sixty-four barrows with an initial body weight of 73.05 ± 2.34 kg were randomly allocated into 1 of 4 dietary treatments in a 2 (100% vs. 125% NRC CP level) × 2 (0 vs. 300 mg/kg GAA) factorial arrangement (n = 7). The feeding trial lasted for 49 d. GAA supplementation significantly reduced drip loss (P = 0.01), free water distribution (T23 peak area ratio) (P = 0.05) and the concentrations of free alanine, threonine, methionine and isoleucine (P < 0.05); but increased total glycine content (P = 0.03) in the longissimus dorsi muscle of finishing pigs regardless of the dietary CP levels. Furthermore, primary myogenic cell differentiation system was employed to investigate the influence of inclusion of GAA on free amino acid concentrations in myotubes (n = 4) and validate the finding in the animal feeding trial. We found that GAA inclusion in culture medium also decreased intracellular concentrations of free alanine, threonine, methionine, isoleucine, valine and proline in differentiated primary myogenic cells in vitro (P < 0.05). Meanwhile, relative to diets with 100% NRC CP level, the intake of diets with 125% NRC CP level improved sarcoplasmic protein solubility, increased the contents of carnosine and total free amino acids as well as flavor amino acids in the longissimus dorsi muscle and decreased backfat thickness at the 6–7th ribs in pigs (P < 0.05). In addition, we observed that the impact of dietary GAA supplementation on the last rib fat thickness, shear force, and free lysine content in the longissimus dorsi muscle was dependent on dietary CP levels (P < 0.05). Collectively, dietary GAA supplementation can reduce drip loss, decrease the concentrations of free amino acids and flavor amino acids of fresh meat independent of dietary CP levels.

Влияние продолжительности сухого созревания и состава посолочных веществ на белки высококачественной говядины

Meat quality largely depends on the maturation conditions and natural biochemical processes that affect its taste, aroma, tenderness, and technological properties. Dry maturation and technological processing attract a lot of scientific attention. The research objective was to study the effect of dry maturation time on the physicochemical parameters of high-quality beef, as well as the effect of a new curing mix on the properties of raw materials.&#x0D; The research featured dorsal-lumbar cuts of high-quality beef on maturation days 21 and 40. Matured meat was tested for the main components, the solubility of sarcoplasmic and myofibrillar proteins, the hydrophobicity of myofibrillar proteins, protein oxidation products, and the activity of catalase and peroxidase. The chemical composition was evaluated depending on the dry maturation time using the arbitration method. The solubility of proteins was determined by the calorimetric method with a biuret reagent. The hydrophobicity of myofibrillar proteins was determined by bromophenol blue reaction, and the activity of catalase and peroxidase was determined by standard methods. Proteins were extracted with potassium phosphate buffer (pH 7.2), while myofibrillar proteins were extracted with Tris-HCl and KCl buffers at pH 7.5 and 7.0. &#x0D; The meat samples were deboned and salted using sodium chloride and a combined mix of 70% magnesium chloride and 30% sodium chloride. The solubility of myofibrillar proteins on day 21 increased by 23.95% but decreased by 14.1% by day 40. The solubility of sarcoplasmic proteins decreased continuously (22.10 and 31.12%, respectively). The obtained data matched the hydrophobicity of proteins. Dry maturation initiated protein oxidation, as demonstrated by carbonyl and sulfhydryl groups of myofibrillar proteins on maturation day 40 (27.85 nmol/L and 27.3 µmol/g of protein, respectively). Sodium chloride and its mix increased the extractability of proteins by 5.2 and 6.9% on day 21 and by 6.8 and 10.6% on day 40 but triggered protein oxidation.&#x0D; Muscle proteins of high-quality beef proved functional after 21 days of dry maturation. The new mix with reduced sodium content can be recommended for high-quality dry-aged beef production.

Effects of Maturation after Slaughter on Physicochemical Properties and Proteins Expression of Goats Meat

In order to investigate the physical and chemical properties of goats during maturation process within 48 h after death, longissimus dorsi muscle of goats at 0, 12, 24 and 48 h after slaughter was taken respectively. The TPA, pH, water retention rate, sarcoplasmic protein solubility and differential expression proteins (DEPs) level were measured respectively to study the change of meat quality at different maturation stages. The results showed as follows: With the extension of post-mortem time point, the pH of goats meat decreased significantly within 48 h (P 0.05). Within 12 h after slaughter, the solubility of myofibrillar proteins in goat meat samples decreased significantly (P<0.05), and then increased gradually (P<0.05), solubility of sarcoplasmic fibers protein increased gradually with the prolongation of post-slaughter time (P<0.05). The glycogen content of Xinjiang goats within 48 h after slaughter was significantly decreased (P<0.05). Compared with 0 h, there were 13 DEPs in the 12 h group, 26 DEPs in the 24 h group, and 69 DEPs in the 48 h group. The expression of enzymes related to energy metabolism was up-regulated from 0 to 48 h, and the expression of proteins related to lamb odor was up-regulated from 24 to 48 h. The tenderness, color and taste of Xinjiang goat meat were superior during the maturation period of 24~48 h after slaughter, the processing and storage during this period could provide basic guarantee for the quality of Xinjiang goats.

Processing Characteristics of Freeze-Dried Pork Powder for Meat Emulsion Gel.

The processing characteristics of freeze-dried pork powder as raw meat for comminuted meat products were compared with those of freeze-thawed pork. The tertiary structural properties, oxidation, and solubility of proteins in the freeze-dried pork powder were investigated. In addition, the properties of the emulsion gels manufactured with freeze-dried pork powder (GFD) and freeze-thawed pork (GFT) at 1.5% and 2.0% NaCl were evaluated. The surface hydrophobicity and intrinsic tryptophan fluorescence intensity of myofibrillar proteins between the freeze-dried pork powder and freeze-thawed pork were similar. However, freeze-dried pork powder had higher carbonyl compounds and lower solubility of sarcoplasmic and myofibrillar proteins than freeze-thawed pork (p<0.05). GFD had higher cooking loss than GFT in 2.0% NaCl, and lower hardness and a* value of GFD were observed regardless of NaCl level (p<0.05). Moreover, GFD had higher malondialdehyde content than GFT at the two NaCl concentrations (p<0.05). Therefore, our study demonstrated that freeze-dried pork powder has lower functional properties than freeze-thawed pork as raw meat for comminuted meat products.

Physicochemical characteristics and textural parameters of restructured pork steaks hydrolysed with bromelain

Enzymatic tenderisation including bromelain enhances underused cuts of meat in emerged restructuring technology. Physicochemical and textural characteristics of restructured pork steak hydrolysed with bromelain for masticatory dysfunction people were evaluated. Restructured pork steak treated with bromelain at 0.05 and 0.1% (w/w) was hydrolysed at 50 °C for 0, 3, 6, 9 and 12 min. The cooking losses of 0.05% (w/w) bromelain for 0, 3 and 6 min were lower than 0.1% (w/w) bromelain samples. The ΔE increased after increasing the enzyme concentration and hydrolysis time. Bromelain-treated samples at higher concentrations showed lower WBSF, KSF and TPA parameters, but cohesiveness of 0.05% (w/w) had higher than 0.1% (w/w) bromelain samples. Total protein, sarcoplasmic protein solubility, TCA-soluble peptide, total collagen and soluble collagen contents were the highest in 0.1% (w/w) bromelain-treated samples for 12 min (P < 0.05). According to SDS-PAGE and SEM, various proteins in the enzyme-treated samples were degraded.

Investigation of the effect of pork compositions on freezing points in different pork cuts by measuring thermal properties and water mobility and distribution.

This work was to compare the difference of freezing point in the four pork cuts (chuck roll, picnic shoulder, loin, and topside) and evaluate the effect of pork compositions on the freezing points. Loin exhibited lower freezing points and accompanied by higher content of unfreezable water, lower relaxation times, and higher proportions of bound water, compared with other pork cuts. Low freezing points of pork may be attributed to high sarcoplasmic protein solubility, due to high sarcoplasmic protein solubility related to increase of bound water proportion and decrease of NMR T2 relaxometry. In addition, correlation analysis revealed that sarcoplasmic protein solubility and ash content were negatively related to the freezing point, which was verified by a quadratic polynomial correlation between the sarcoplasmic protein solubility and the freezing point in vitro. These results could help to better understand the freezing point of pork and provide more theories for improving superchilled storage.

Changes in Physical Meat Traits, Protein Solubility, and the Microstructure of Different Beef Muscles during Post-Mortem Aging.

This study was performed to compare the differences in pH, myofibril fragmentation index (MFI), total protein solubility (TPS), sarcoplasmic protein solubility (SPS), myofibrillar protein solubility (MPS), and the microstructure of seven beef muscles during aging. From the six beef carcasses of Xinjiang brown cattle, a total of 252 samples from semitendinosus (ST), longissimus thoracis (LT), rhomboideus (RH), gastrocnemius (GN), infraspinatus (IN), psoas major (PM), and biceps femoris (BF) muscles were collected, portioned, and assigned to six aging periods (1, 3, 7, 9, 11, and 14 day/s) and 42 samples were used per storage period. IN muscle showed the highest pH (p < 0.05) from 1 to 14 days and the lowest TPS (p < 0.01) from 9 to 14 days with respect to the other muscles. Moreover, the changes in IN were further supported by transmission electron microscopy due to the destruction of the myofibril structure. The highest value of MFI was tested in ST muscle from 7 to 14 days. The total protein solubility in PM, RH, and GN muscles were not affected (p > 0.05) as the aging period increased. The lowest TPS was found in the RH muscle on day 1, 3, and 7 and in the IN muscle on day 9, 11, and 14. The pH showed negative correlations with the MFI, TPS, and MPS (p < 0.01). The results suggest that changes in protein solubility and muscle fiber structure are related to muscle location in the carcass during aging. These results provide new insights to optimize the processing and storage of different beef muscles and enhance our understanding of the biological characteristics of Xinjiang brown cattle muscles.

Functional/physicochemical properties and oxidative stability of ground meat from broilers reared under different photoperiods

Long photoperiods are used in the broiler industry to maximize animal performance, though the impact on meat quality remains poorly understood. The current study evaluated the impact of photoperiod on functional/physicochemical properties and oxidative stability of meat through broiler processing. Ross 308 broilers (n = 432) were randomly assigned to 4 photoperiod treatments (hours in L = light, D = dark): 20L:4D, 18L:6D, 16L:8D, or 12L:12D with 6 pens per treatment. At 42 D of age, 2 broilers per pen (n = 12 per treatment) were harvested under standard conditions. Broiler tenderloin (M. Pectoralis minor) and leg muscles were removed at 1 D postmortem and frozen/stored at −40°C. After 24 h thawing at 2°C, the samples were deboned, ground, and formed into patties in 3 independent batches. Photoperiod had no impact on pH, water-holding capacity, textural profile, meat emulsion activity index, and thiol content (P > 0.05). The patties from 12L:12D and 16L:8D had lower CIE b∗ (yellowness) values than 18L:6D and 20L:4D (P < 0.05), whereas 12L:12D had lower chroma (color intensity) values than other treatments (P < 0.05). The meat from 20L:4D exhibited lower sarcoplasmic protein solubility than other treatments (P < 0.05), whereas both 20L:4D and 18L:6D exhibited lower total protein solubility than 12L:12D (P < 0.05). Higher transmission values (indication of protein denaturation) were observed in 20L:4D than in other treatments (P < 0.05), whereas 12L:12D also maintained lower values than both 18L:6D and 16L:8D (P < 0.05). There was an interaction (P < 0.05) between photoperiod and display storage on 2-thiobarbituric acid reactive substances values, where the patties from 12L:12D maintained less lipid oxidation compared with the patties from other treatments. Results of this study suggest photoperiod has limited impact on meat quality attributes, though rearing broilers with a 12L:12D lighting schedule may be beneficial in reducing protein denaturation and improving lipid stability.

Using shear force, sarcomere length, particle size, collagen content, and protein solubility metrics to predict consumer acceptance of aged beef tenderness.

In this study, the relationship between sensory evaluation and several objective metrics of beef tenderness was tested. Objective metrics included shear force, sarcomere length, collagen content, myofibrillar, and sarcoplasmic protein solubility and particle size analysis. These results were compared to consumer panel scores of tenderness for the same aged beef striploin (longissimus lumborum muscle) samples. There was found to be a significant relationship between sarcomere length, shear force, and particle size with tenderness scores. Collagen content and protein solubilities were not associated to tenderness scores (p > 0.05). Sarcomere length contributions for explaining tenderness variation were overlapped by the contributions of shear force (collinearity). Independent models demonstrated that the lower 95% confidence interval of the fitted regression line exceeded 50% acceptance of tenderness when shear force values <42.6 N and when particle size values <198 μm. We can recommend these as thresholds for consumer acceptance of beef tenderness, although considerations of sample type, analytical methodology, and consumer demographics should be made prior to their adoption. This provision was based on the variation in tenderness scores evident between individual panelists and experimental striploins.

Effect of spaghetti meat abnormality on broiler chicken breast meat composition and technological quality

The effects of spaghetti meat (SM) myopathy and sampling location on chicken breast meat physical traits, composition, and protein functionality were investigated using 30 normal (N) and 30 SM boneless fillets. Weight, drip loss, pH, and color traits were determined on intact fillets. Proximate composition, water holding capacity, mineral profile, SDS-PAGE, myofibrillar, and sarcoplasmic protein solubility, and emulsifying properties were assessed on both the superficial (S) and deep (D) layers of the breasts. SM fillets were heavier (P < 0.0001) and exhibited greater drip loss (P = 0.0131) and higher b* index on the skin side of the muscle (P < 0.0001). Muscle condition by layer interaction effect revealed that the superficial portion of SM fillets (SM-S) exhibited the highest moisture (P = 0.0003) and fat contents (P = 0.0011) coupled with the lowest protein (P < 0.0001) and ash contents (P = 0.0458). Total and soluble collagen amounts were higher in N-S and SM-S groups compared with N-D and SM-D (P < 0.0001). SM-S group exhibited the highest calcium (P = 0.0035) and sodium (P < 0.0001) levels. Overall, the myopathy had only minor impacts on protein profiles, while the muscle layer exerted a more remarkable effect. SM fillets exhibited higher pH but a lower myofibrillar protein solubility (P < 0.0001). Salt-induced water uptake, cooking loss, and final yield values suggested a potential impairment of water-holding capacity in SM-affected meat. Sarcoplasmic and myofibrillar emulsion activity indexes were similar between the 2 muscle conditions, but the stability of the emulsions was lower in SM meat. Overall, significant layer and muscle condition by layer effects were not observed in the functional properties of the breast meat. SM exerted a profound and negative impact on breast meat composition that led to detrimental consequences on functionality traits. Given the fundamental role of protein quality for meat processing, these data suggest that a further step toward the understanding of this myopathy should be the investigation of intrinsic protein characteristics.

The coordination of dietary valine and isoleucine on water holding capacity, pH value and protein solubility of fresh meat in finishing pigs

To investigate coordination of dietary levels of valine (Val) and isoleucine (Ile) on carcass traits and meat quality in pigs, 72 of 73.8 ± 1.6 kg crossbred barrows were randomly divided into a 2 (0.31% vs. 0.65% standard ileum digestible (SID) Val) × 2 (0.25% vs. 0.53% SID Ile) factorial arrangement. As a result, high dietary valine decreased myosin heavy-chain (MyHC)-I mRNA expression, pH24 h value, bound water amount (T21 peak area ratio), sarcoplasmic protein solubility and water holding capacity (WHC) of meat (P < .05). Meanwhile, high dietary isoleucine increased pH24 h value, sarcomere length (P < .05) and tend to decrease drip loss (P = .07). The significant interactions between valine and isoleucine were observed on backfat thickness, water distribution forms and myofibrillar protein solubility (P < .05) of pork. High valine diets undermined WHC of meat probably through decreasing pH24 h value and sarcoplasmic protein solubility considering their significant correlations with drip loss

Functional/Physicochemical Properties and Oxidative Stability of Ground Meat from Broilers Exposed to Different Photoperiods

ObjectivesProlonged photoperiod (light) is a common practice in the broiler industry to maximize feed intake, growth and yield. Several studies, however, have found negative impacts of extended photoperiod on animal welfare-related characteristics (e.g., leg abnormalities). While the previous research has primarily focused on animal growth/welfare aspects, the effect of photoperiod on functional properties and quality attributes of broiler meat has not been evaluated. Thus, this study was aimed to determine functional properties, physicochemical attributes and oxidative stability of ground meat from broilers reared under different photoperiod conditions.Materials and MethodsRoss 308 broiler chicks (n = 432) were assigned to 4 rooms with 6 pens per treatment, which were equipped with one of the following photoperiods (T20, T18, T16, and T12; the hours of lighting per day), started from Day 15. At 42 d of age, the broilers (n = 12/treatment) were randomly taken, slaughtered and chilled for 24 h at 2°C. At 1 d postmortem, tenderloins and leg muscles were separated from the carcasses and stored at –40°C until further processing. In three batches, meat samples were ground using 1/4 in plate and formed into patties (100 g each). The ground samples were measured for pH, protein solubility, emulsion activity index, protein denaturation, salt-induced water uptake and subsequent cooking loss and final yield. The patties were displayed at 2°C under light (l × 1800) and color stability, lipid oxidation (TBARS) and thiol contents were examined. The patties were also measured for purge/cooking loss and texture profile analysis (TPA). All data were analyzed using the PROC MIXED procedure of SAS (v.9.4). Means were separated using least significant differences (P &lt; 0.05).ResultsT20 samples had the lowest sarcoplasmic protein solubility among treatments, while T18 had a lower myofibrillar protein solubility compared to other treatments (P &lt; 0.05). The emulsion activity index of T20 was higher in sarcoplasmic fraction than T12 (P &lt; 0.05). T20 group also had a lower extractable protein concentration compared to other treatments, which subsequently resulted in an increase in protein denaturation (P &lt; 0.05). T20 samples had a lower value of pH, salt-induced water uptake, and cooking loss, while T18 had a lower final yield than T16 and T12 (P &lt; 0.05). No differences in physicochemical traits of patties were found between treatments, indicated by TPA, purge and cooking loss results (P &gt; 0.05), however T20 had a greater display weight loss than T12 (P &lt; 0.05). T20 patties maintained the highest L* and hue angle values during entire display, which could be attributed to its inferior water-holding capacity (P &lt; 0.05). Both lipid (TBARS) and protein oxidation (thiol content) were increased with display (P &lt; 0.05), but no significant photoperiod effect was found (P &gt; 0.05).ConclusionThe results from the present study indicate that extended photoperiod would result in adverse impacts on functional/technological properties and oxidative stability of broiler meat. This is the first study reporting the importance of broiler housing condition (photoperiod) and its subsequent impacts on final meat quality and processing properties. The findings would provide insights into development of mitigating strategies for the poultry industry to prevent quality deteriorations of broiler meat due to the extended photoperiod.

Changes in chicken meat proteins during microwave and electric oven cooking

Alterations in proteins and some functional properties of chicken thigh (TM) and breast meats (BM) cooked with microwave oven (MWO) were evaluated in comparison to traditional electric oven (EO). Cooking loss in both TM and BM did not differ between the cooking methods (p > .05). In TM, MWO cooking resulted in higher water-holding capacity (WHC) than EO (p < .05). Sarcoplasmic protein solubility of TM decreased with MWO cooking while both cooking methods resulted in reduction in both sarcoplasmic and myofibrillar protein solubility in BM (p < .05). TM and BM cooked with MWO were harder in texture (p < .05) than EO cooked samples as determined in texture profile analysis. The intensity of myofibrillar protein bands in the Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) decreased after cooking by both MWO and EO, whereas EO cooked samples demonstrated more fragmentation in both sarcoplasmic and myofibrillar proteins in comparison with MWO cooked chicken meats. Practical applications Microwave cooking is an alternative, efficient method to reduce time, energy, and cost as compared to conventional oven cooking. In oven cooking, thermal energy is transmitted quite slow from the surface of the food to the center, whereas microwave energy is converted into heat inside the food itself which provides homogeneous heat distribution. In the present study, the effects of microwave and EO cooking methods on some quality characteristics, mainly proteins of TM and BM were evaluated. It was found that microwave cooking resulted in harder texture, but better WHC to its counterpart which also caused more degradation in myofibrillar and sarcoplasmic proteins. Because microwaves shorten cooking time, lowers the energy consumption, and makes the production process sustainable and more efficient than with conventional ovens, while better preserving the nutritional quality of the product becomes a sound alternative. Therefore, it is worth to keep exploring this novel cooking approach that might render significant advantages in industrial applications.

Superchilled, chilled and frozen storage of Atlantic mackerel (Scomber scombrus) fillets – changes in texture, drip loss, protein solubility and oxidation

SummaryChanges in quality characteristics in relation to protease activity and protein oxidation in chilled, superchilled and frozen mackerel fillets during storage were studied. The solubility of sarcoplasmic proteins was quite stable in mackerel samples for all storage experiments, whereas the solubility of myofibrillar proteins decreased in both superchilled and frozen samples. A significant correlation (r = 0.983, P &lt; 0.05) between the increased activity of cathepsin B+L in chilled fillets and softening of the fish flesh during storage was revealed. Contrary with chilled samples, the texture of superchilled mackerel fillets became tougher along the storage period, which can be explained by a higher rate of myofibrillar oxidation (r = 0.940, P &lt; 0.05). The hardness and drip loss decreased slightly at the end of frozen storage. Superchilling preserved the quality of mackerel fillets with the least side effects in relation to protein solubility, drip loss and softening of the fish tissue as compared to chilled and frozen storage.

Tenderization of Camel Meat by Alkaline and Acidic Proteases from Mullet (Mugil cephalus) Viscera

Recently, tenderness of meat become more interest due to its relation with meat quality. Camel meat chunks were tenderized by injected with 20 and 40U of alkaline and acidic proteases which extracted from mullet viscera for 2, 4 and 6 hrs at room temperature. Alkaline and acidic proteases increased moisture content, WHC values, solubility of collagen, sarcoplasmic, myofibrillar and total protein of treated camel meat chunks. On the other hand, decreased protein content, cooking loss and shear force values of treated camel meat chunks. Sensory evaluation appeared improvement in juiciness, tenderness and overall acceptability of all treated camel meat chunks compared to untreated camel meat (control sample) with no significant differences in appearance and flavor between all camel meat samples. The results indicated that, camel meat chunks were tenderized and improved their quality by treated with alkaline and acidic mullet proteases.

Degradation of myofibrillar, sarcoplasmic and connective tissue proteins by plant proteolytic enzymes and their impact on camel meat tenderness.

Inside round muscles (Adductor) from camels treated with bromelain or ficin or papain at 50 or 100ppm were subsequently stored at 4°C for 4days to study the impact on quality attributes, protein degradation and textural changes. Results revealed that papain (100ppm) treated camel meat showed higher drip loss and lower water holding capacity compared to other treatments. Total protein, sarcoplasmic protein solubility, trichloroacetic acid (TCA)-soluble peptides and soluble collagen were higher in papain and bromelain treated samples at 100ppm compared to other treatments. Electrophoretic profile of whole camel meat, isolated sarcoplasmic and myofibrillar proteins depicted a noticeable degradation of various proteins in enzyme treated samples, with papain and bromelain (100ppm) displaying pronounced effect. Meat treated with papain at 100ppm displayed lower hardness and shear force (P < 0.05). Thus, enzymes treatment at 100ppm displayed good potential to tenderize camel meat with the papain being more effective among all.

Optimization of Replacing Pork Meat with Yellow Worm (Tenebrio molitor L.) for Frankfurters.

The effects of replacing pork meat with yellow mealworms on the physicochemical properties and sensory characteristics of frankfurters were investigated in this study. The control (50% pork ham), T1 (45% pork ham + 5% yellow mealworm), T2 (40% pork ham + 10% yellow mealworm), T3 (35% pork ham + 15% yellow mealworm), T4 (30% pork ham + 20% yellow mealworm), T5 (25% pork ham + 25% yellow mealworm), and T6 (20% pork ham + 30% yellow mealworm) were prepared, replacing lean pork meat with yellow mealworm. The moisture content, lightness, sarcoplasmic protein solubility, hardness, gumminess, chewiness, and apparent viscosity of frankfurters with yellow mealworm were lower than those of the control (p<0.05), whereas the content of protein and ash, pH, and yellowness of frankfurters with yellow mealworm were higher than those of the control (p<0.05). The fat content of frankfurters in T1 (p<0.05) was the highest, and the fat content of treatments decreased with increasing yellow mealworm concentrations (p<0.05). Frankfurters with increasing yellow mealworm concentrations had lower color, flavor, off-flavor, and juiciness scores. The overall acceptability was not significantly different in the control, T1, and T2 (p>0.05). Thus, the results of this study showed that replacing lean pork meat with up to 10% yellow mealworm successfully maintained the quality of frankfurters at a level similar to that of the regular control frankfurters.

Effects of chilled-then-frozen storage (up to 52 weeks) on an indicator of protein oxidation and indices of protein degradation in lamb M. longissimus lumborum

This study investigated the protein oxidation properties of lamb following chilled-then-frozen storage. Experimental (n=360) M. longissimus lumborum (LL) were randomly sampled from the boning room of a commercial Australian abattoir, at 24h post mortem, and assigned to five chilled storage periods (0, 2, 4, 6 and 8weeks) and six subsequent frozen storage periods (0, 4, 8, 12, 24 and 52weeks). Upon completion of each storage treatment combination, corresponding LL were sub-sectioned and analysed for carbonyl content, protein solubility, nitrate/nitrite content, particle size analysis and estimated myoglobin fractions. The association between these protein measures and shear force was also explored. During chilled storage, particle size and sarcoplasmic protein solubility decreased which indicated protein degradation, while frozen storage only affected myoglobin oxidation. Tenderness was best explained by decreased particle size, decreased deoxymyoglobin and increased oxymyoglobin. No carbonyl effects were observed. It can be concluded that, according to these analyses, that in chilled-then-frozen lamb carbonyl formation was negligible.

Effects of different thawing methods on the quality of chicken breast

SummaryFreezing and thawing technologies are widely used in meat industry. This study aimed to investigate the effects of freezing and different thawing methods (Control group, CG; water immersing thawing, WT; low temperature combined with high‐humidity thawing, LT; combined thawing 1 (WT 15 min, then LT), CT1; combined thawing 2 (LT 2 h, then WT), CT2) on the quality of chicken breast. The results showed that all thawing methods significantly increased shear force value, the gap between muscle fibres, the contents of malondialdehyde (MDA) and carbonyl compounds, meanwhile, decreased the pH, CIE a* value, total protein solubility and sarcoplasmic protein solubility, compared with CG (P &lt; 0.05). Among different thawing methods, LT was most effective in decreasing thawing loss but it had the highest contents of MDA and carbonyl compounds (P &lt; 0.05). CT1 significantly decreased shear force value and MDA content (P &lt; 0.05). Overall, freezing and thawing process had a detrimental effect on the quality of chicken breast, and the extent was pronounced with different thawing methods. On the basis of shortening thawing time and keeping meat quality, the results of this study suggested that CT1 could be chosen as the better thawing method.