Sarcoplasmic Protein Solubility Research Articles

Effects of enhancing vitamin D status by 25-hydroxycholecalciferol supplementation, alone or in combination with calcium and phosphorus, on sternum mineralisation and breast meat quality in broilers

ABSTRACT1. The aim of the present study was to examine the effects of improving vitamin D status in broiler diets by supplementary 25-hydroxycholecalciferol (25OHD3), alone or in combination with calcium (Ca) and available phosphorus (aP), on live performance, sternum mineralisation and breast meat quality in broilers.2. A total of 936 1-d-old Ross 308 broilers were used in the study. After gender determination at the hatchery, chicks from each sex were randomly distributed into three dietary treatments. The following dietary treatments were used in the experiment from hatch to 38 d: (1) A control diet formulated to meet all of the nutrient requirements of broiler chicks according to the management guide; (2) The control diet supplemented with 18.7–15.0 µg/kg of 25OHD3; and (3) The control diet supplemented with 18.7–15.0 µg/kg of 25OHD3 plus Ca + aP.3. Improvement in vitamin D status by 25OHD3 supplementation, alone or in combination with Ca and aP, had no effect on body weight and feed conversion ratio of broilers.4. The serum 25OHD3 concentration significantly increased with 25OHD3 and 25OHD3 plus Ca + aP supplementation (P < 0.05), whereas the ionised Ca and Mg concentrations remained unchanged.5. Sternum absolute weight, ash content and the concentrations of Ca and P significantly increased (P < 0.01) with supplementation of 25OHD3, alone or in combination with Ca + aP.6. Supplemental 25OHD3, alone or in combination with Ca + aP, slightly increased pH24 (P = 0.05) and decreased (P < 0.01) squeezable water loss in breast meat, whereas it had no significant effect on lightness, yellowness and sarcoplasmic protein solubility.7. In conclusion, the results suggested that enhancing vitamin D status by 25OHD3 supplementation alone or in combination with Ca + aP may improve sternum structure and mineral accretion. Furthermore, supplemental 25OHD3, even in a nutritionally complete diet, may offer an effective way to improve protein solubility in female broilers.

Effects of high-voltage electrostatic field treatment on the thawing rate and post-thawing quality of frozen rabbit meat

Abstract The thawing rate and post-thawing quality of frozen rabbit meat after the use of high-voltage electrostatic fields (HVEFs) were investigated in this study. The thawing efficiency could be significantly improved at voltages of − 15, − 20 or − 25 kV, and HVEF treatment resulted in 0.5–1.7log reductions in the number of microorganisms. The rabbit meat thawed at − 20 kV had optimal qualities, including a high water-holding capacity (WHC) and good texture quality. Although there were structural alterations of the myoglobin treated at − 20 kV HVEF, the sarcoplasmic protein solubility was not reduced. Additionally, the − 20 kV HVEF treatment led to less denaturation of the myofibrillar proteins than with still air thawing, as demonstrated by the actin denaturation enthalpy (− 0.26 ± 0.085 and − 0.12 ± 0.040 J/g, respectively). Finally, thawing at − 20 kV HVEF had little influence on the relaxation of water, including the water mobility, in rabbit meat. Industrial relevance This study found that HVEF thawing could shorten thawing time by 60%. Moreover, compared with air thawing, − 20 kV HVEF thawing led to less denaturation of the myofibrillar proteins, which is very important for further processing in the rabbit meat industry.

Effects of dietary starch types on growth performance, meat quality and myofibre type of finishing pigs

To investigate the effects of dietary starch types on growth performance and meat quality of finishing pigs, ninety barrows (68.0±2.0kg) were randomly allotted to three experimental diets with five replicates of six pigs, containing pure waxy maize starch (WMS), nonwaxy maize starch (NMS) and pea starch (PS) (amylose/amylopectin were 0.07, 0.19 and 0.28 respectively). Compared with WMS diet, PS diet increased the average daily gain, loin eye area, pH45 value, NMR transverse relaxation (T2)2 peak area ratio and sarcoplasmic protein solubility, decreased the feed to gain ratio, back fat, drip loss, cooking loss and T23 peak area ratio (P<0.05). Moreover, PS diet increased the myosin heavy-chain (MyHC)-I and IIa levels, decreased the MyHC-IIb level, decreased the miR23a level and increased its target gene level, increased the miR499 level and decreased its target gene level (P<0.05). Diet with high amylose content might be beneficial to the growth performance and meat quality of finishing pigs.

Effect of acute heat stress and slaughter processing on poultry meat quality and postmortem carbohydrate metabolism

This study investigated the effects of acute heat stress and slaughter processing on poultry meat quality and carbohydrate metabolism. Broilers (200) were randomly divided into 2 groups receiving heat stress (HS; 36°C for one h), compared to a non-stressed control (C). At slaughter, each group was further divided into 2 groups for slaughter processing (L = laboratory; F = commercial factory). L group breasts were removed immediately after bleeding without carcass scalding or defeathering, and stored at 4°C. F group broilers were scalded (60°C, 45 s) after bleeding and defeathering. Then the breasts were removed and cooled in ice water until the core temperature was ≤4°C. Rates of Pectoralis core temperature and pH decline were changed by slaughter processing, but only HS affected ultimate pH in group L. HS muscles had higher L* values (P < 0.05) than controls at 24 h postmortem. Laboratory processing “hot-deboning” increased drip loss, which resulted in a lower cooked loss (P < 0.05). Postmortem glycolysis was affected only by HS. The speed of lactic acid accumulation and glycogen degradation was faster in the HS group than controls at 5 min postmortem. During storage the glycolysis rates were not different (P > 0.05). Sarcoplasmic protein solubility was higher in F processed birds (P < 0.05). HS decreased the solubility of myofibrillar and total protein in the L-slaughtered birds. Thus, HS caused a higher frequency of accelerated muscle glycolysis than controls. Factory processing (chilling) could not completely eliminate the effects of accelerated glycolysis caused by pre-slaughter HS.

Breast Meat Quality and Protein Functionality of Broilers with Different Probiotic Levels and Cyclic Heat Challenge Exposure

This study was performed to evaluate the effect of probiotic feeding level on meat quality and protein functionality of breast muscle from chickens exposed to cyclic heat challenge. A total of 180 one-d-old male chicks were randomly allocated in 36 floor pens. From Day 15, the birds were exposed to 32°C for 10 h daily until the end of the experiment (Day 46). Three dietary treatments containing different levels of probiotic (a mixture of 4 lactic acid bacteria, 5.0 × 109 cfu/g) were prepared; regular diet without probiotic (control), regular diet with 0.5 g of probiotic/kg feed (probiotic 0.5) and regular diet with 1.0 g of probiotic/kg feed (probiotic 1). Both breast muscles (M. pectoralis major) were collected at 24 h postmortem, and the same side breast muscle was assigned to each experiment 1 (meat quality analysis, n = 6) and 2 (protein functionality analysis, n = 3). Probiotic feeding level did not affect initial pH and temperature declines (P &gt; 0.05) of breast muscle until 6 h postmortem. However, the breast muscles from probiotic 1 group (5.92) showed a significantly higher ultimate pH than those from control (5.78) or probiotic 0.5 (5.82) groups at 24 h postmortem. No differences in chemical composition (moisture, protein, fat, ash, and phospholipids), water-holding capacity (cooking loss and display weight loss), shear force, and lipid oxidation stability were found in breast muscles from chickens exposed to cyclic heat challenge, regardless of probiotic levels (P &gt; 0.05). An increase in probiotic level increased total protein solubility (P = 0.0004) and emulsion activity index of sarcoplasmic protein (P = 0.0032) of ground chicken breast. The results from the current study suggest that the supplementation of this commercial probiotic product could partially improve protein functionality of breast muscles from chickens exposed to cyclic heat challenge, in a dose-dependent manner within the applied level.

Impact of white striping on functionality attributes of broiler breast meat

The influence of white striping (WS) on the water-holding capacity (WHC) and protein functionality attributes of broiler breast meat was investigated. Boneless breast fillets (Pectoralis major) were collected from the deboning line of a commercial processing plant and categorized by WS score (normal, moderate, severe). The physical (weight, pH, CIE-color values), water-holding capacity (salt-induced water uptake, cook loss, final yield), protein functionality (solubility, emulsifying activity), and protein composition (SDS-PAGE) characteristics of the fillets were measured in three experiments. Breast meat with WS exhibited greater fillet weights, higher pH, and similar color values (L*a*b*) to normal fillets. In experiment 1, fillets were frozen-thawed prior to analysis. The WS condition reduced thaw loss, sarcoplasmic protein solubility, and the emulsifying activity of the myofibrillar proteins, but did not significantly affect salt-induced water uptake, cook loss, final yield, or myofibrillar protein solubility. In experiment 2, breast meat was analyzed fresh and after a freeze-thaw cycle. Freezing samples prior to analysis negatively influenced WHC and reduced sarcoplasmic protein solubility in both WS and normal fillets. In fresh and frozen-thawed meat, the WS condition decreased sarcoplasmic protein solubility but did not significantly alter WHC or myofibrillar protein solubility. For experiment 3, fillets were portioned into 3 sections (Location A, cranial end-ventral surface; Location B, cranial end-dorsal surface; Location C, caudal end). The effects of WS on WHC and protein solubility were dependent upon breast fillet sampling location. Fillets with WS exhibited lower salt-induced water uptake, greater cook loss, and lower sarcoplasmic protein solubility than normal fillets when sampled from location A. SDS-PAGE analysis indicated that differences in the composition of sarcoplasmic and myofibrillar protein fractions between WS and normal fillets were influenced by sampling location. These results suggest that WS diminishes the WHC and protein functionality of broiler breast meat, but demonstrate that the WS effects on these traits are not uniform throughout the breast muscle.

Effects of dietary lysine and methionine supplementation on Ross 708 male broilers from 21 to 42 days of age (II): breast meat quality

SUMMARY In a previous companion study, we found that broiler growth performance and meat yield were improved by the feeding of increased levels of dietary lysine (Lys) and methionine (Met). In the current study, dietary Lys and Met supplementation were evaluated for their effect on the breast (pectoralis major) meat quality of male Ross × Ross 708 broilers. A completely randomized block design with a 2 × 4 factorial arrangement of treatments was applied (10 blocks and 8 treatments/block). The diets, including 2 Lys levels (1.013 and 1.216%) and 4 Met levels (0.304, 0.380, 0.456, and 0.532%), were fed from 21 to 42 d of age in the form of pellets, and broilers were processed at 42 d of age. Data were analyzed by 2-way ANOVA using the MIXED procedures of SAS 9.2. Lysine supplementation yielded breast meat with increased sarcoplasmic protein (soluble protein) solubility (P = 0.007) and pH (less protein denaturation; P

Effect of irradiated pork on physicochemical properties of meat emulsions

Abstract The effect of pork irradiated with doses up to 10 kGy on meat emulsions formulated with carboxy methyl cellulose (CMC) was investigated. Raw pork was vacuums packaged at a thickness of 2.0 cm and irradiated by X-ray linear accelerator (15 kW, 5 MeV). The emulsion had higher lightness, myofibrillar protein solubility, total protein solubility, and apparent viscosity with increasing doses, whereas cooking loss, total expressible fluid separation, and hardness decreased. There were no significant differences in fat separation, sarcoplasmic protein solubility, springiness, and cohesiveness. Our results indicated that it is treatment by ionizing radiation which causes the effects the physicochemical properties of the final raw meat product.

Relationship between water-holding capacity and protein denaturation in broiler breast meat

The objective of this study was to determine the relationship between water-holding capacity (WHC) attributes and protein denaturation in broiler breast meat. Boneless skinless breast fillets (n = 72) were collected from a commercial processing plant at 2 h postmortem and segregated into low-WHC and high-WHC groups based on muscle pH and color (L*a*b*). At 6 and 24 h postmortem, brine uptake (%), cooking loss (%), and protein solubility (sarcoplasmic and myofibrillar) were measured and protein fractions were analyzed using SDS-PAGE. Drip loss accumulation (%) was measured after storage for 2 and 7 days postmortem. High-WHC fillets exhibited lower L*-lightness values and greater pH values at 2 and 24 h postmortem than low-WHC fillets. High-WHC fillets had greater brine uptake and less cooking loss at both 6 and 24 h postmortem compared to low-WHC fillets. Aging from 6 to 24 h postmortem increased brine uptake in high-WHC fillets, but did not affect cooking loss in either low-WHC or high-WHC fillets. Drip loss accumulation was greater in low-WHC fillets at both 2 and 7 days postmortem. Myofibrillar protein solubility decreased with postmortem time but was not different between low-WHC and high-WHC fillets. Sarcoplasmic protein solubility increased with postmortem time and was greater in high-WHC fillets. SDS-PAGE analysis indicated that low-WHC fillets exhibited more glycogen phosphorylase denaturation than high-WHC fillets as evidenced by a more extensive shift of the protein from the sarcoplasmic to the myofibrillar protein fraction. Correlation analysis revealed that overall protein solubility measurements were not related to WHC attributes but that the degree of glycogen phosphorylase denaturation was significantly correlated (|r| = 0.52 to 0.80) to measures of WHC. Data indicated that WHC differences in broiler breast fillets were not due to differences in myofibrillar protein denaturation and suggested that the denaturation of sarcoplasmic proteins onto myofibrils may influence WHC in breast meat.

Relationship of changes in quality attributes and protein solubility of ground beef under pasteurization conditions

Cook loss and shrinkage are important parameters for evaluating quality attributes of processed meats with the most important determinant being the thermal stability of proteins in the muscle tissue. In this study, we found that these attributes correlated with a loss of soluble sarcoplasmic proteins (SSP) and soluble myofibrillar proteins (SMP) in ground beef patties during pasteurization (65–90 °C, 1–60 min). Cook loss in beef patties was linearly correlated with the area shrinkage (R2 = 0.95), and with the loss of SSP (R2 = 0.87), SMP (R2 = 0.85), and total soluble proteins (TSP; R2 = 0.89). About 60–80% of SSP and SMP were rapidly lost in the first 2–5 min of heating, then decreased at lower rate until reaching an equilibrium value of approximately 22% of SSP and 20% of SMP of their initial values. Cook loss (29–35%) and area shrinkage (19–28%) also occurred rapidly in the first 2–5 min of heating. The concentration of TSP in exudate decreased, but the net weight of TSP and percentage of TSP (2–10%) lost in the exudate increased with heating time while the sum of TSP in exudate and meat decreased.

Quantity and functionality of protein fractions in chicken breast fillets affected by white striping

Recently, white striations parallel to muscle fibers direction have been observed on the surface of chicken breast, which could be ascribed to intensive growth selection. The aim of this study was to evaluate the effect of white striping on chemical composition with special emphasis on myofibrillar and sarcoplasmic protein fractions that are relevant to the processing features of chicken breast meat. During this study, a total of 12 pectoralis major muscles from both normal and white striped fillets were used to evaluate chemical composition, protein solubility (sarcoplasmic, myofibrillar, and total protein solubility), protein quantity (sarcoplasmic, myofibrillar, and stromal proteins), water holding capacity, and protein profile by SDS-PAGE analysis. White-striped fillets exhibited a higher percentage of moisture (75.4 vs. 73.8%;P < 0.01), intramuscular fat (2.15 vs. 0.98%;P < 0.01), and collagen (1.36 vs. 1.22%;P < 0.01), and lower content of protein (18.7 vs. 22.8%;P < 0.01) and ash (1.14 vs. 1.34%;P < 0.01), in comparison with normal fillets. There was a great decline in myofibrillar (14.0 vs. 8.7%;P < 0.01) and sarcoplasmic (3.2 vs. 2.6%;P < 0.01) content and solubility as well as an increase in cooking loss (33.7 vs. 27.4%;P < 0.05) due to white striping defects. Moreover, gel electrophoresis showed that the concentration of 3 myofibrillar proteins corresponding to actin (42 kDa); LC1, slow-twitch light chain myosin (27.5 kDa); and LC3, fast-twitch light chain myosin (16 kDa), and almost all sarcoplasmic proteins were lower than normal. In conclusion, the findings of this study revealed that chicken breast meat with white striping defect had different chemical composition (more fat and less protein) and protein quality and quantity (low content of myofibrillar proteins and high content of stromal proteins) with respect to normal meat. Furthermore, white striped fillets had lower protein functionality (higher cooking loss). All the former changes indicate that white striping has great impact on quality characteristics of chicken breast meat.

Effects of gamma irradiation on physicochemical properties of heat-induced gel prepared with chicken salt-soluble proteins

The technological effects of gamma irradiation (0, 3, 7, and 10kGy) on chicken salt-soluble meat proteins in a model system were investigated. There were no significant differences in protein, fat, and ash content, and sarcoplasmic protein solubility among all samples. The samples with increasing gamma irradiation levels had higher pH, lightness, yellowness, and apparent viscosity, whereas moisture content, water holding capacity, redness, myofibrillar protein solubility, total protein solubility, hardness, springiness, cohesiveness, gumminess, and chewiness were the highest in the unirradiated control. The result from meat products using gamma irradiation was intended to provide a basic resource processing technology.

Comparison of protein degradation, protein oxidation, and μ-calpain activation between pale, soft, and exudative and red, firm, and nonexudative pork during postmortem aging.

The objective of this study was to investigate the differences in protein modifications between pale, soft, and exudative (PSE) and red, firm, and nonexudative (RFN) pork during postmortem (PM) aging. Longissimus dorsi (LD) including 8 PSE and 8 RFN muscles were individually removed from 16 carcasses. These 16 LD muscles were vacuum packaged at 24 h after slaughter and stored at 4°C for 1, 3, and 5 d. The centrifugation loss, drip loss, color, protein solubility, protein oxidation, protein degradation including desmin, troponin T, and integrin, and μ-calpain activation were determined. The pH of PSE samples was significantly lower than that of RFN samples at both 1 and 24 h PM (P < 0.05). The L* values of PSE pork were significantly greater than that of RFN pork at different time point during PM storage (P < 0.01). The centrifugation loss of PSE samples at d 1 was extremely greater than samples from RFN pork (P < 0.01). The cumulative drip loss for d 0 to 1, d 0 to 3, and d 0 to 5 in PSE pork were significantly greater than that from RFN pork (P < 0.05). The carbonyl content of myofibrillar proteins was not significantly different between PSE and RFN pork samples (P > 0.05). In addition, PSE pork presented a lower solubility of sarcoplasmic protein, myofibrillar protein, and total protein than RFN pork except the solubility of myofibrillar protein at d 1 (P < 0.05). The intensity of intact desmin and troponin T 2 in PSE pork at d 3 and 5 were significantly greater than that in RFN pork (P < 0.05), whereas no significant difference was detected at d 1. The intensity of intact troponin T 1 in PSE pork at d 5 was greater than that in RFN pork (P < 0.05). However, more degradation products of integrin were detected in PSE pork compared to that of RFN pork at d 1 (P < 0.05). Red, firm, and nonexudative pork presented lower intensity of intact 80 kDa calpain and greater intensity of autolyzed 76 kDa product compared to PSE pork (P < 0.01). The results indicate that the degree of μ-calpain activation, the extent of protein degradation including desmin and integrin, and the level of protein solubility in PSE pork could contribute to its low water holding capacity during PM storage.

Impact of carcass scalding and chilling on muscle proteins and meat quality of broiler breast fillets

The objective of this study was to determine the effects of broiler carcass scalding and chilling methods on meat quality and muscle proteins. During processing, carcasses were hard (60 °C, 1.5 min) or soft (52.8 °C, 3 min) scalded, and either immersion chilled (IC: 0.5 °C, 40 min) or air chilled (AC: 0.5 °C, 120 min). Breast fillets were deboned at 4 h postmortem and used for measuring meat quality and muscle protein characteristics. Scalding by chilling treatment interaction effects on meat quality were not observed. Air chilled carcasses had greater pH24, and reduced drip loss and shear force compared to IC carcasses. Cook yield, color (L*a*b*), and moisture content were not different between chilling treatments. Scalding treatments did not influence quality traits. Sarcoplasmic protein solubility was not influenced by chilling treatment, but was greater in hard versus soft scalded carcasses. Myofibrillar protein solubility was greater in fillets from soft scalded IC carcasses. Alterations in the electrophoretic profiles of the myofibrillar and sarcoplasmic proteins due to treatments indicated minor changes in protein degradation and solubility. Data suggest that while only chilling method influenced meat quality, both scalding and chilling methods influenced protein solubility and degradation in breast fillets deboned 4 h postmortem.

Pre-rigor carcass stretching counteracts the negative effects of high rigor temperature on tenderness and water-holding capacity – using lamb muscles as a model

High pre-rigor muscle temperature has negative consequences on quality and has been predominantly studied in the excised longissimus muscle of beef and lamb carcasses. There is little data on other muscles, the application in whole carcasses or potential amelioration techniques such as stretching. This study evaluated the effects of electrical stimulation, high pre-rigor temperature and stretching of lamb sides on quality traits and protein denaturation in four leg muscles [gluteus medius (GM), rectus femoris (RF), semimembranosus (SM) and semitendinosus (ST)]. Twenty lamb carcasses were used with two electrical stimulation treatments (stimulated or non-stimulated, +/−) and two pre-rigor temperature treatments (chilled at 2°C directly after slaughter, or held in 37°C water for 4.5 h before transfer to a 2°C chiller) applied. One side of each carcass was suspended from the Achilles tendon, whereas the other side was stretched by allowing the leg to drop and tying it to the ribs. Electrical stimulation did not influence the different traits except for pH fall post slaughter and myosin denaturation. Stretching resulted in greater muscle and sarcomere lengths for the GM, SM and ST, but a decrease in sarcomere length for the RF. For the non-stretched GM and SM, the 37°C treatment resulted in tougher meat at 1 and 8 days post mortem compared with the 2°C treatment. In contrast, the stretched 37°C treatment resulted in more tender meat for the GM, SM and ST at 1 day post mortem compared with the 2°C treatment. For all muscles, the 37°C treatment resulted in a decrease in the water-holding capacity (increased purge, surface exudate and cooking losses). The magnitude of this effect was generally diminished by stretching for the GM, SM and ST, but for the RF, (which was not stretched by the treatment) this effect was reversed. The 37°C treatment resulted in paler meat (increased L*-values) for the GM, SM and ST relative to the 2°C treatment. The observed effects of the 37°C treatment on water-holding capacity and colour could be explained by the effects of this treatment on indicators of protein denaturation (sarcoplasmic protein solubility and myofibrillar ATPase activity), which were decreased for the GM, SM and ST. The response to both temperature and stretching varied between the muscles, due to different anatomical location and also due to postulated differences in the fibre types. In conclusion, pre-rigor stretching of lamb sides can counteract the negative effects of high early post-mortem temperature on tenderness and water-holding capacity for those muscles that are stretched as a result of this hanging method.

Effect of pre-rigor temperature incubation on sarcoplasmic protein solubility, calpain activity and meat properties in porcine muscle

The aim of the study was to investigate the effect of pre-rigor temperature incubation on sarcoplasmic protein characteristics in relation to meat properties within porcine muscle. Porcine Longissimus dorsi muscles were incubated at temperatures of 0, 10, 20, 30 and 40 °C to 6 h post mortem. Incubation at 40 °C induced a significant decrease of sarcoplasmic protein solubility and an increase in proteins in the myofibrillar fraction. The protein relocation was followed till 72 h post mortem but had largely been completed by the end of the temperature incubation at 6 h. SDS-PAGE and Western blot analyses suggested that phosphorylase and creatine kinase precipitated onto the myofilaments during incubation at 40 °C. Drip loss increased following incubation at 40 °C, indicating that the precipitation of phosphorylase and creatine kinase may be a factor of reduced water-holding capacity at the combination of high temperature and low pH. Incubation at 40 °C resulted in substantially lower shear force in parallel with loss of extractable activity of μ- and m-calpain, suggesting a rapid activation of both enzymes at high temperatures and low pH early post mortem.

Impact of High Pressure Processing on the Functional Aspects of Beef Muscle Injected with Salt and/or Sodium Phosphates

This study aimed to determine the interactions among salt (NaCl), sodium phosphate (SP) and mild high pressure processing (HPP) in brine-injected beef. Beef strip loin segments were injected to 10% over initial weight with solutions containing water and various levels of salt (0, 2 or 4% of solution) and/or SP (0 or 4% of solution). Pieces from the loin sections were exposed to varying pressure levels (0.1, 152 or 303 MPa) and evaluated for selected quality and biochemical characteristics. Use of SP and pressure application increased pH by ∼0.2 units. L* values were increased by pressure and decreased by SP. Redness (a*) increased at 303 MPa. Purge increases due to pressure were mitigated by SP. Pressure application at 303 MPa reduced total and sarcoplasmic protein solubility by 24 and 32%, respectively. There were no beneficial interactions among salt or SP and HPP. However, results indicate SP may prevent yield loss due to HPP. Practical Application This study has demonstrated that beneficial interactions between HPP and salt are not achieved in brine-injected whole muscle beef when salt levels are at or below 0.4% of final product weight. However, use of sodium phosphates prevented reduced yields and alleviated some of the color change incurred by HPP at mild pressures.

Characterization of Textural Properties and Changes of Myofibrillar and Sarcoplasmic Proteins in Salame Felino During Ripening

Textural properties and changes of myofibrillar and sarcoplasmic proteins of salame Felino, a typical Italian dry-cured fermented sausage, were studied during ripening. Hardness, chewiness, and gumminess increased over the ripening period. Adhesiveness showed a gradual but significant decrease after 14 days and further at 28 days of ripening. A remarkable increase of the proteolysis index and a significant decrease of myofibrillar and sarcoplasmic protein solubility were observed. Hardness showed a significant negative correlation with myofibrillar protein solubility. Sarcoplasmic proteins appeared to be more susceptible to degradation.

Relationship between pork quality and characteristics of muscle fibers classified by the distribution of myosin heavy chain isoforms1

A total of six fiber types, including four pure types (type I, IIA, IIX, and IIB) and two hybrid types (type IIAX and IIXB), were classified according to the expression of myosin heavy chain (MHC) isoforms by immunohistochemistry with MHC specific monoclonal antibodies. The comparison of the muscle fiber characteristics and pork quality between pork quality groups (DFD: dark, firm, and dry; PSE: pale, soft, and exudative; RFN: reddish pink, firm, and nonexudative; and RSE: reddish pink, soft, and exudative) classified by muscle pH, drip loss, and lightness was conducted and the relationship of myofiber characteristics to pork quality was investigated. The DFD group had the highest value of IIAX fiber density (P<0.05). The DFD group also showed the greatest fiber relative area of type I, IIA, and IIAX (P<0.05) whereas there were no significant differences in area composition for types I, IIA, and IIAX among the other groups including PSE, RFN, and RSE (P>0.05). The DFD group had the highest cross-sectional area (CSA) in types I, IIA, and IIX among the groups. The increase in density of type IIAX was related with the higher pH and the lower hue and drip loss. An increase in the fiber number composition of hybrid type IIXB increased the lightness and cooking loss and decreased sarcoplasmic protein solubility (SPS). Regarding fiber relative area, pure type I and IIA and hybrid type IIAX were greater in the DFD group and had lower lightness and drip loss. Hybrid type IIAX influences the desirability of the pork due to its association with low lightness and high pH and water-holding capacity (WHC). In contrast, type IIXB was related to poor quality pork, including pale color, low WHC in cooked meat, and low SPS.

Changes in Shear Parameters, Protein Degradation and Ultrastructure of Pork Following Water Bath and Ohmic Cooking

The objective of this study was to investigate the effects of ohmic (OH) and water bath (WB) cooking on shear parameters, protein degradation and ultrastructure changes of porcine longissimus dorsi muscle at the same endpoint temperatures (EPTs; range, 20–100 °C). The cooking loss and Warner–Bratzler shear force of the OH-cooked meat were significantly lower (P < 0.05) while protein solubility, pH and endothermic transition temperature were higher than those obtained by WB cooking at the same EPTs (range, 20–80 °C). Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis showed that during OH cooking, the meat had slightly fainter protein bands than that of WB-cooked ones. Less obvious shrinkage of the sarcomere and loss in the structure of Z discs were detected especially in OH-cooked meat at EPTs (100 °C). Strong correlations among pH, cooking loss, Warner–Bratzler shear force, sarcoplasmic protein solubility, Tmax2, and Tmax3 were observed in meat following OH cooking.