Tenderness of pork m. longissimus thoracis et lumborum after accelerated boning. Part II. Effect of post-slaughter ageing

This research investigated the effect of ageing time (0-10 days) at 2?°C on tenderness of pork longissimus muscle after either rigor boning (RB) or accelerated boning (removal from carcass within 30 min post slaughter) and temperature conditioning at either 0 or 14?°C. Ageing occurred most rapidly in muscles conditioned at 14?°C- maximum tenderization occurred by 4 days post-mortem. RB muscles and muscles conditioned at 0?°C aged more slowly and took 8 and 10 days, respectively, to reach a comparable level of tenderness. Temperature conditioning at 14?°C, produced muscles which had lower drip loss and lighter surface colour.     

Effect of calcium infusion on tenderness and ageing rate of pork m. longissimus thoracis et lumborum after accelerated boning

The effect of calcium chloride infusion at either 0.5 or 6 h post slaughter on tenderness, ageing rate and meat quality of pork longissimus muscle that had been boned at rigor or had undergone accelerated processing and conditioning at either 0?°C or 14?°C was investigated. The time of calcium infusion had no effect on the initial WBSF values or the aging rate. However, calcium infusion overall resulted in lower WBSF initially (1-day post-mortem) and also after 6 days ageing at 2?°C regardless of the processing procedures used. Calcium infusion did not, however, increase the ageing rate compared to comparable treatments that had not been calcium infused. Based on this observation and the myofibrillar fragmentation index results, it was concluded that the increased tenderness due to calcium infusion was not due to increased proteolysis as has been previously postulated, but was due to either a direct effect of calcium on tenderness, or an indirect effect of calcium via increased post-mortem glycolysis and pH decline rate resulting in reduced cold shortening. Calcium infusion had detrimental effects on drip loss and meat colour.     

Tenderness of pork m. longissimus thoracis et lumborum after accelerated boning. Part I. Effect of temperature conditioning

This research investigated the effect on tenderness and meat quality of temperature conditioning at 0, 7, 14 or 21?°C of pork longissimus muscle after accelerated boning (removal from the carcass within 30 min post slaughter). The conditioning temperature had no effect (P>0.05) on tenderness at the end of the conditioning period (i.e. at the onset of rigor) but had a significant effect (P<0.05) after the muscles were aged for four days at 2?°C. After aging, the muscles conditioned at 14?°C were more tender than muscles conditioned at the other three temperatures; the muscles conditioned at 0?°C were tougher than the muscles conditioned at the higher three temperatures. Conditioning at 14?°C produced muscles that had lighter surface colour and lower drip loss due to prevention of cold toughening which occurred at lower temperatures or protein denaturation at the higher temperatures.     

Variation of the sensory quality within the m. longissimus thoracis et lumborum of PSE and normal pork

This study evaluated the variation in instrumental and sensory meat quality within the m. longissimus thoracis et lumborum of carcasses with normal and PSE meat. Out of 80 slaughtered pigs, respectively, 9 and 7 carcasses were selected with a pH30 value > or=5.80 (normal pork) and a pH30 value <5.80 (PSE pork). Instrumental and sensory meat quality measurements were performed at three locations on these carcasses: longissimus thoracis (LT), longissimus thoracis et lumborum: (LTL-mid-loin) and longissimus lumborum (LL). Meat of the thoracis site (LT) was paler, but more favourable for pH45, cooking loss, juiciness, tenderness and preference scores than meat of the mid-loin part. The lumborum site (LL) was more or less in between the other two locations for meat quality, but closer to the LTL than the LT site. The meat quality variation within the m. longissimus thoracis et lumborum followed a similar pattern for normal and PSE carcasses. It can be concluded that the mid-loin part is best suited as a reference place for meat quality assessment, if one wants to eliminate carcasses with unacceptable meat.     

Predicting variability of ageing and toughness in beef M. Longissimus lumborum et thoracis

The object of this study was to determine muscle characteristics which might predict meat toughness. Eleven Charolais cattle were slaughtered at approximately 26 months of age and the Longissimus lumborum et thoracis muscle was taken 1 hr post mortem and stored at 12 °C for 24 hr and then at 4 °C.

The average half-life for ageing in these raw muscles was 4.6 days but the toughness varied widely between the animals. Toughness varied 3-fold and the rate of ageing varied 20-fold between animals.

Correlations were done to determine which characteristics might explain this variability. Toughness was correlated positively with increase in oxidative status of muscle and the initial levels of calpastatin. Toughness was correlated negatively with the initial levels of μ- and m-calpains and cysteine and serine proteinase inhibitors, the initial pH values and the rates of their decline. The rates of ageing were highly correlated positively with the initial levels of proteinase inhibitors and the rates of decline of calpastatin and negatively with the ultimate amounts of expressible juice.

There was a wide variability in tenderness in M. Longissimus lumborum et thoracis from similar animals. Variations in metabolism and enzyme activity controlled by inhibitors and calpains appear to be largely responsible for this variability.     

The use of visible and near infrared reflectance spectroscopy to predict beef M. longissimus thoracis et lumborum quality attributes

Visible and near infrared reflectance spectroscopy was used to predict pH at 24 h (pH24) post-mortem, sarcomere length (SL), cooking loss (CL), Warner–Bratzler Shear Force (WBSF) and colour parameters (L^∗, a^∗, b^∗) in beef cattle samples. Samples from M. longissimus thoracis et lumborum from 30 bulls were aged at 4 °C for 1, 3, 7 and 14 days and analysed for pH, SL, CL, WBSF and colour. NIRS calibrations for pH24, luminosity at 0 (L^∗t0) and 60 min (L^∗t60) showed good predictability (R² = 0.97, 0.85 and 0.82; SECV = 0.10, 1.16, 1.36, respectively), whereas those related to the rest of the parameters were poorer.     

The effect of ultra-rapid chilling and subsequent ageing on the calpain/calpastatin system and myofibrillar degradation in lamb M. longissimus thoracis et lumborum

The effect of ultra-rapid chilling (-20°C) on the proteolytic degradation of myofibrillar proteins during ageing, by the calpain/calpastatin system in lamb was investigated. Carcasses (36) were ultra-rapidly chilled (-20°C for 3.5 h followed by 20.5 h at +4°C) or chilling at +4°C for 24 h. After chilling all carcasses were stored at +4°C for a further 4 days. Samples of M. longissimus thoracis et lumborum were taken for Warner-Bratzler shear force measurement, sarcomere length, SDS-PAGE and enzyme activity analysis. Ultra-rapid chilling (-20°C) had no effect on the proteolytic degradation of myofibrillar proteins by the calpain/calpastatin system compared to conventional chilling (+4°C). However, no difference in tenderness was found between the two chilling regimes at 1 or 5 days postmortem so differences in myofibrillar degradation or enzyme activity would not be expected.     

Distribution of intramuscular lipid throughout M. longissimus thoracis et lumborum in Japanese Black, Japanese Shorthorn, Holstein and Japanese Black crossbreds

Intramuscular lipid content of M. longissimus thoracis et lumborum was determined at five locations within the ribeye muscle from 267 Japanese Black, Japanese Shorthorn, Holstein and Japanese Black crossbred steers and heifers or cows in order to investigate the distribution of marbling. Breed was a highly significant (P < 0·001) source of variation for amount of marbling at each of the locations measured. Percentage of lipid was higher at the extremities of the muscle than in the middle part and was not affected by sex at any location except for opposite the 6th rib (P > 0·05). Regression equations were derived which relate the percentage of lipid at various locations within M. longissimus thoracis et lumborum to that opposite the 6th rib. A substantial portion of the variation in marbling observed at the other locations could be accounted for by marbling at the 6th rib (R(2) = 0·73-0·90). These data confirm that marbling varies within the ribeye muscle but suggest that it is rather consistent in the distribution pattern exhibited by Japanese Black cattle and their crosses.     

Effect of restricted feeding and realimentation periods on pork quality and fatty acid profile of M. longissimus thoracis

An experiment with 94 fattening pigs (48 gilts and 46 barrows) was conducted to determine the effect of feeding 25% restricted diets at different body weights on meat quality and fatty acid profile of M. longissimus thoracis (LT). During the 84 days of the experiment (4 periods, 21 days each), animals with an initial weight of about 31 kg were fed in different periods of observation ad libitum (A) or restricted diets (R) in groups AAAA, AARA, RAAA and RARA. After 21 days of the experiment, the restricted-fed pigs, compared to those fed ad libitum, had a lower total fat content of M. longissimus thoracis (P<0.05), higher shear force (P=0.068), and lower proportions of SFA (C14:0, C18:0 P<0.05) and MUFA and higher proportions of PUFA (C20:4, C22:4 P<0.05) in the fatty acid profile. Three weeks after the restricted feed supply was lifted, the total fat content in LT muscle was higher than in animals fed ad libitum throughout (2.34 vs. 2.02), very close after the next 3 weeks of realimentation (3.16 vs. 3.15) and lower after another 3 weeks (3.19 vs. 3.49). Regardless of the time at which restricted feeding was started and the number of restricted feeding periods, the total fat content in the LT muscle at the end of the experiment was similar or lower in groups RAAA, AARA and RARA, compared to group AAAA. The coefficient of correlation between the total fat content in LT and the shear force was -0.36 (P<0.01). Colour, pH and drip loss did not depend on the level of nutrition. After 84 days of observation, animals from groups RARA and AARA, compared to pigs from groups AAAA and RAAA, were characterized by a slightly higher shear force of LT, lower SFA and MUFA (P<0.001), and higher n-6 PUFA (P<0.01) and n-3 PUFA (P<0.01) proportions in the fatty acid profile. The fatty acid profiles of AAAA pigs and pigs undergoing a 63-day realimentation period (RAAA) were similar. Regardless of the feeding scheme, the n-6:n-3 ratio exceeded 10 in all the groups.     

Iron content in musculus longissimus lumborum et thoracis (m.l.l.t.) of fattening pigs

Pork is among the most essential dietary sources of iron in Germany, considering its beneficial absorption rate. During 1997 and 1998 meat samples from 52 pigs per year were collected at the Thuringian performance testing station in order to examine the total iron content of pork. Musculus longissismus lumborum et thoracis (13./14. thoracic vertebra) from the right side of the carcasses were prepared for analyses. The total iron content was measured by atomic emission spectroscopy with inductively coupled plasma. The iron content of the meat was 4.18 +/- 0.97 mg/kg fresh material. This result was significantly lower than corresponding data from literature. An influence of the genetic composition of the pigs examined on the total iron content could be observed. The daily gain (R = -0.26) and intramuscular fat content (R = -0.28) were inversely correlated to the iron content. However, the lean meat proportion (R = 0.26) as well as haem pigment content (R = 0.27) were directly correlated to the total iron content of the meat.     

Ultrasonic scanning measurements of the longissimus thoracis et lumborum muscle to predict carcass muscle content in sheep

Nineteen Omani sheep (average 26 kg body weight) were scanned over the 6th rib, 12th rib and the second-last lumbar vertebra, to determine the maximum depth (B), circumference, area of the cross-section and volume of the longissimus thoracis et lumborum (LD) muscle. The volume of the muscle was estimated by multiplying the average area of its cross-section obtained at the three sites by its length. After slaughter, the LD muscle was dissected out, frozen, and its maximum depth, circumference, length, weight and volume were determined. Correlation and regression analyses were carried out to evaluate relationships between scanning and real measurements and between scanning measurements and carcass total muscle content. Generally there were positive correlations (r = 0.43-0.66) between the LD scanning measurements made at the 12th rib and the corresponding measurements made on the dissected muscle. The volume of the LD muscle estimated from scanning was positively correlated (r = 0.59) with its real volume which was correlated with its weight (r = 0.51) and consequently with the total carcass muscle content (r = 0.69). Ultrasonic scanning can be used to predict the circumference and volume of the LD muscle. These may be used for prediction of total carcass muscle content in sheep in addition to traditional measurements of the muscle (the maximum depth B) and area.     

Calpains and calpastatin from cold-shortened bovine M. longissimus lumborum

Sections of beef longissimus lumborum from four animals were held after 1 hr post mortem at either 0 ° (cold-shortened) or at 15 °C (controls). After 24 hr, the levels of μ- and m-calpains were the same in both treatments and about 30% and 85% of their initial levels respectively. The level of calpastatin at 24 h was higher in cold-shortened (100%) than in controls (60% of its initial level). During subsequent storage at 4 °C, the activities of calpains and calpastatin decreased similarly in extracts from both cold-shortened and control muscles. The similar levels of μ-calpain during the first 24 hr post mortem but at the lower temperature suggest that there is less activity under cold-shortening conditions. This, combined with the increased calpastatin levels, would produce less proteolysis by the calpain system. Reduced proteolysis is therefore a factor which should be considered in an understanding of the mechanism of cold-shortening toughness.     

The effects of finishing diet and postmortem ageing on the eating quality of the M. longissimus thoracis of electrically stimulated Brahman steer carcasses

Beef from cattle finished on grass will be of similar quality to that from cattle finished on grain when their carcasses are processed using best practice protocols. To test this hypothesis, carcasses of twenty Brahman steers, finished to 400 kg live weight on either Buffel grass pasture (n=10) or grain (n=10), were electrically stimulated with 400 V for 50 s 45 min postmortem, and their beef quality assessed 1 and 14 days postmortem. Hot weight, rump subcutaneous fat thickness and animal rate of growth in the 205 days preceding slaughter were recorded for each carcass as potential influences on beef quality. Quality of the M. longissimus thoracis (LT) at 1 and 14 days postmortem was evaluated using peak Warner-Bratzler shear force, compression, pH, cooking loss and taste panel acceptability, as well as by moisture and crude fat contents measured at 1 day postmortem. Results showed that steers finished on pasture grew the slowest and had the least subcutaneous fat at the same carcass weight. LT from carcasses of steers finished on pasture also had the shortest mean sarcomere lengths, suggesting these muscles may have been cold-affected, but there was no effect of diet on peak shear force. LT from carcasses of steers finished on pasture had the highest mean compression value, possibly because of increased collagen cross-linking associated with slow growth or increased exercise. Ageing significantly decreased LT peak shear force and compression values and increased cooking loss, L (?), a (?) and b (?) values. Taste panellists rated the aged, grass-finished beef the most tender and the best quality; however, the taste panel in this study may have favoured LT from grass-finished steers because it was significantly juicier than LT from the grain-finished steer carcasses. These results indicated that carcass composition and processing conditions interact to exert a greater effect on LT toughness and sensory acceptability than finishing diet. Ageing LT from steers finished on grass improved its colour, and thus may enhance its consumer acceptability.     

Variation in Flavor and Textural Descriptions of Cooked Steaks from Bovine m. longissimus thoracis et lumborum from Different Production and Aging Regimes

ABSTRACT: Free choice profiling (FCP) and generalized Procrustes analysis (GPA) were used to assess flavor differences in cooked bovine m. longissimus thoracis et lumborum (LTL) steaks sourced wholesale or from steers fed the same diet. Wholesale steaks were from LTL muscles that were either unaged or aged for 93 d with high or low visible marbling from old and young grass- and grain-finished cattle. The GPA of this sensory data showed that the 1st dimension contrasted grass- and grain-finished beef and accounted for 44.1% of the total variance, whereas the 2nd dimension contrasted unaged and aged beef and accounted for 22.9% of the variance. GPA was also used to assess flavor variation in cooked LTL steaks aged 4 or 14 d postmortem from 10 steers finished on the same diet, and the 1st 2 dimensions accounted for 39% of the total variance. Univariate analysis of beef aroma, flavor intensity, tenderness, and juiciness showed only tenderness increased with aging ( P = 0.041) and Duncan's multiple comparison test on all FCP data indicated that aging beef up to 14 d shifted beef sensory characteristics toward increased tenderness, juiciness, and fatty flavor. The results of these studies showed that distinct flavors exist in beef from cattle finished in different production systems and that there is less variation in the flavor of beef from steers produced on the same farm than in beef available for general retail.     

Compensatory growth response as a strategy to enhance tenderness in entire male and female pork M. longissimus thoracis

The effects of restrictive feeding strategies aimed at promoting a compensatory growth response were investigated with respect to tenderness improvement in pork M. longissimus thoracis. Compensatory growth response is defined by increased weight in pigs fed ad libitum after a period with restricted feeding compared to pigs fed ad libitum the entire fattening period. Specifically, the aim was to study the sensory textural characteristics after female and entire male pigs have been exposed to restrictions in either energy, protein or both in specific growth periods. It was found that textural differences were caused by feeding strategies and not related to variation in intramuscular fat, which did not vary significantly between genders. The female pigs demonstrated compensatory growth response and the texture was significantly (P<0.001) improved by low dietary level of energy from day 50 to 90 and normal dietary level of protein during the entire feeding period. For the entire male pigs, low level of protein in the late feeding period significantly (P<0.05) improved the texture. Also, low level of protein and normal level of energy in the early feeding period resulted in improved tenderness. However, these texture improvements were deemed not to be an effect of compensatory growth since the entire male pigs did not compensate for the feeding restriction in the early feeding period. The tenderness enhancement for the entire male pigs compromised the production results in terms of 7-15% lower carcass weight.     

Effect of low and high pulsed electric field on the quality and nutritional minerals in cold boned beef M. longissimus et lumborum

The present research investigated the effects of low PEF (LPEF, 2.5 kV, 200 Hz and 20 μs) and high PEF (HPEF, 10 kV, 200 Hz and 20 μs) on the quality of cold-boned beef loins at 1 and 14 days of post-treatment. HPEF increased (P < 0.001) the temperature of the beef M. longissimus et lumborum (LL) samples. HPEF samples had higher (P = 0.007) shear force than LPEF samples and control samples were not different from either. HPEF beef LL samples had higher L* values and lower a* values (P < 0.001) compared to LPEF and control samples. Higher lipid oxidation (P = 0.013) was found in HPEF samples compared to LPEF samples. Lower (P < 0.01) P, K and Fe concentrations were found in HPEF samples compared to LPEF samples. The results suggest that high intensity PEF treatment can negatively affect the quality of beef.     

The relationship between pig genetics, myosin heavy chain I, biochemical traits and quality of M. longissimus thoracis

The relationship between muscle biochemical traits, myosin heavy chain I and meat quality of longissimus thoracis was studied using gilts from five divergent porcine lines (A to E) (carcass weight: 83.7±8.7 kg). Intramuscular fat (IMF) and haem pigments content as well as myosin heavy chain 1 (MyHC I) percentage and the activity of lactate dehydrogenase (LDH) and isocitrate dehydrogenase (ICDH) were determined. Only group E, a well conformed line of pigs, included the halothane positive genotype. The presence of the Hal gene in this line resulted in meat of poorer quality in terms of meat of higher exudate compared to line D, also a well conformed line of predominantly Pietrain origin but being halothane gene free. Line C presented the highest IMF content (2.02%) as well as high oxidative characteristics (MyHC I, 10.0%; LDH/ICDH, 1.92 μmol nmol(-1); ICDH activity, 1.78 nmol min(-1) g(-1)) and the lowest drip losses (5.3%). According to a principal component analysis including MyHC I, biochemical traits and meat quality parameters, line C was characterized by a high IMF content and oxidative traits, and line B by a high glycolytic metabolism. Line E was distinguished by high drip losses and by low pH(45) and pH(u). In conclusion, several observed differences in muscle metabolism between lines free of the halothane gene (A, B, C and D) must be caused by other "genetic background" factors.     

Changes in biogenic amine contents, non-protein nitrogen and crude protein during curing and thermal processing of M. longissimus, pars lumborum of pork

Changes in histamine, putrescine, cadaverine and tyramine, weight, dry matter, crude protein and non-protein nitrogen were studied during immersion-curing (brine with NaNO₂ and NaCl content of 0.6 g/l and 99.4 g/l, respectively and brine with NaNO₂ and NaCl content of 0.6 g/l and 199.4 g/l, respectively) and boiling and grilling (70 °C core temperature) of both “fresh” and “stored” (storage 5 days at 4 °C) pork loin chops. Amine concentrations were significantly higher in “stored” pork; this difference was preserved during most of the processing techniques. Correlations of amines with nonprotein nitrogen were weak and not significant, but strong and significant for putrescine: cadaverine (r=0.89) as well as putrescine: tyramine (r=0.95). Amine reductions for “fresh” pork were not pronounced. In “stored” pork both cooking in water (water/meat = 1:1, weight base) and curing in the less concentrated brine resulted in mean reductions of 65, 77, and 68% for putrescine, cadaverine and tyramine, respectively. Boiling of cured samples yielded reductions of 50–77, 74–80, 67–71, and 77–91% for histamine, tyramine, putrescine and cadaverine, respectively.

Influence of intramuscular fat content on the quality of pig meat - 2. Consumer acceptability of m. longissimus lumborum

The present study is part of a project which aimed to examine the influence of intramuscular fat (IMF) content on sensory attributes and consumer acceptability of pork. Two experiments were conducted to evaluate consumer acceptability of pork chops with varying IMF level in muscle Longissimus lumborum (LL). Each experiment used 32 castrated male pigs selected after slaughter either from 125 Duroc × Landrace (Experiment 1) or 102 Tia Meslan × Landrace (Experiment 2) crossbred animals, and showing large variability in LL IMF content: from <1.5 to >3.5% in Experiment 1 and from 1.25 to 3.25% in Experiment 2. A group of 56 consumers evaluated various items on rib-eye (LL muscle trimmed of backfat) (Experiment 1) and on entire chops trimmed of backfat (Experiment 2). Data from Experiment 1 indicate that an increase in IMF level is associated with an increase in visual perception of fat and a corresponding decrease in the willingness to eat and purchase the meat, when expressed before tasting. The latter effect disappeared after the consumers had tasted the meat, probably due to a positive effect of increase IMF, up to 3.5%, on the perception of texture and taste. In Experiment 2, where entire chops were evaluated, the perception of visible fat was not affected by IMF level, probably due to the lack of variation in the level of intermuscular fat between the four IMF groups. The willingness to eat and purchase the meat were unaffected by IMF level, whereas the perception of texture and taste was enhanced with increased IMF levels up to 3.25%. The present data suggest that the acceptability of pork may be improved by increasing IMF level but: (1) this effect disappeared for IMF levels higher than 3.5%, which are associated with a high risk of meat rejection due to visible fat and (2) the positive effect of increased IMF probably holds true as long as it is not associated with an increase in the level of intermuscular fat.