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.     

Tenderness, ageing rate and meat quality of pork M. longissimus thoracis et lumborum after accelerated boning

The impact of accelerated boning on tenderness, ageing rate and meat quality of pork longissimus muscle was investigated. Accelerated boning of eight Large White×Landrace pork carcasses at 30 min post-mortem followed by chilling at 0°C resulted in tougher pork with higher drip loss and a darker surface lightness relative to conventional boning at 24 h post-mortem. The increased toughness was still observed at 4 days post-mortem, a time by which 80% of ageing generally had occurred as seen in experiment 2. The increased toughness could be attributed to cold shortening and a reduction in proteolysis.     

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.     

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.     

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.     

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.     

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.     

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.     

The influence of season on quality characteristics of hot-boned beef m. longissimus thoracis

Samples of m. longissimus thoracis (LT) muscle were randomly collected from 70 Omani beef cattle 1 h after slaughter between August 2001 and July 2002 in the Muscat Municipality central slaughterhouse to investigate the effect of seasonal parameters on meat quality during the hot and cool seasons of Oman. The collection period (12 months) was divided into two seasons according to ambient temperatures and relative humidity and termed: Cool Season (November–March with average temperature of 21.2±1.40 °C and 57.9±1.61% relative humidity) and Hot Season (April–October with average temperature of 34.3±1.67 °C and 48.8±7.57% relative humidity). The season had a significant effect on meat quality characteristics of the LT muscle. Muscles collected during the hot season had significantly (P<0.001) higher ultimate pH values (6.24) with significantly (P<0.001) lower Warner–Bratzler (WB) shear force values (10.12) than those collected during the cool season (5.54 and 15.58). In these hot-boned samples, there was a linear relationship between ultimate pH and WB shear values. Cooking loss was significantly (P<0.001) higher for cool season samples (26.01%) than from hot season samples (19.75%). Beef from the hot season group had significantly (P<0.001) darker meat than that of the cold season group, based on L* (31.45 vs 35.58), a* (18.53 vs 23.19) and b* (4.16 vs 6.40) colour measurements. There was a linear relationship between ultimate pH and cooking loss, L*, a* and b*. These results indicated that heat stress (>30 °C) lead to physiological stress in beef cattle, which in turn increased muscle ultimate pH and influenced related meat quality characteristics.     

Changes in colour of beef m. longissimus dorsi muscle during ageing

The effects of vacuum packaging, chilling rate (slow or fast), and fat cover thickness (?4 mm or 7-8 mm) on the colour parameters of beef m. longissimus dorsi muscle were assessed during ageing. The m. longissimus dorsi muscle was aged on the carcass or in vacuum packaging. Muscle samples for analysis were taken on days 0 (24 hr post mortem), 2, 4, 8, 12 and 16 to ascertain the parameters. Ageing time influenced all colour parameters, while chilling rate affected lightness ('L'), yellowness ('b'), and hue angle difference (HD), and fat cover thickness influenced 'L' and 'b' only.     

Relationships between sensory and objective measures of meat tenderness of beef m. longissimus thoracis from bulls and steers

This study assessed whether relationships between sensory and objective measures of beef tenderness were different for beef from bulls and steers. Trained panelists and instruments were used to measure tenderness of m. longissimus thoracis from bulls (n=58) and steers (n=59). Four measures of sensory tenderness (hardness, cohesiveness, toughness and chewiness) were closely correlated with each other, and moderately correlated with mechanical measures using a Warner-Bratzler device, a MIRINZ tenderometer and a compression cell in an Instron device. With increasing values of objective measures, sensory scores increased at a decreasing rate. Use of a general-least-squares model with sensory measures as the dependent variable and objective measures as covariates (linear and quadratic), showed that, after adjustment to a constant objective measure, significant differences between bulls and steers in sensory measures of toughness remained (P<0.001). Adjusted sensory measures also decreased with increasing ultimate pH in some instances. The bull/steer effects on adjusted sensory measures were smaller when regressions were fitted within the two groups. It is concluded that when using a common prediction equation to estimate sensory scores from objective measures, it can be expected that groups or individual samples with higher scores will tend to be under-estimated, and those with lower scores, over-estimated.     

电刺激对牛背最长肌中钙激活酶活性及嫩度的影响

通过对中国杂交黄牛(鲁西黄牛×西门塔尔)牛背最长肌中Calpains活性及剪切力值的分析,研究了电刺激对牛背最长肌宰后成熟过程中Calpains活性及牛肉嫩度的影响。结果表明:电刺激显著提高了μ-calpain的活性(P<0.05),降低了calpastatin对μ-calpain的抑制作用,提高了牛背最长肌的嫩度,缩短了牛肉的成熟时间;但电刺激仅在宰后成熟1h,显著提高了m-calpain的活性(P<0.05);宰后成熟24h、3d,与对照组之间差异不显著(P>0.05),试验结果证实,电刺激通过对Calpains体系的影响,改变了牛肉的成熟速度,显著的改善了牛肉的嫩度。     

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.

Effect of selection for growth rate on the ageing of myofibrils, meat texture properties and the muscle proteolytic potential of m. longissimus in rabbits

The effect of selection for growth rate on the degradation of the myofibrillar proteins and on meat texture properties of rabbit longissimus muscle at two ageing times (1 and 7 days) was studied as well as its effect on the proteolytic potential of the muscle. Two groups of contemporary animals (20 rabbits per group), one selected for growth rate (S) for 14 generations and the other unselected control group (C) were compared. The control group was formed from the offspring of the embryos belonging to the 7th generation and was compared with selected animals belonging to 21st generation. Myofibrillar protein degradation was studied by SDS-PAGE electrophoresis (12.5% and 4-15% polyacrylamide gels) followed by densitometric analysis of the pherograms. Texture properties were evaluated by Warner-Bratzler (WB) test and Texture profile analysis (TPA). The activities of proteolytic enzymes calpains and cathepsins and of their inhibitors were determined in the muscle at 24h. Densitometric analysis of the pherograms of samples aged 7 days showed an extra 30kDa band and the disappearance of a band with higher molecular weight than the myosin heavy chain with respect to samples aged 24h in both groups of rabbits. TPA results showed that cohesiveness was significantly lower in meat at 7 days than at 24h (P<0.0001), whereas springiness and chewiness presented a clear tendency to be lower at 7 days than at 24h (P=0.0646 and P=0.0764, respectively). Regarding the genetic type, S animals presented higher hardness and chewiness than C rabbits. Shear firmness (WB test) was significantly (P<0.0001) higher for S group, whereas no significant differences in shear force and area were found. No significant effect (P>0.05) of ageing time was detected using WB test. Selection for growth rate did not affect the activities of proteolytic enzymes or their inhibitors.     

"Chilled" pork - Part II. Consumer perception of sensory quality

The objective of this study was to compare consumer perception of the sensory quality of grilled Canadian pork destined for Japanese and domestic markets, with particular reference to export selection criteria imposed by Japanese importers and transportation conditions. Consumers from Quebec, Canada tasted local and export quality pork subjected to "chilled" (aged 43days at -1.7°C) or conventional ageing (5days at 3.1°C). Consumers' scores (out of 10) were higher (P<0.05) in the "chilled" than conventionally aged pork for tenderness (6.8 vs 5.7), juiciness (6.6 vs 6.0), taste liking (6.4 vs 5.9) and overall acceptability (6.7 vs 6.1). When informed that the conventionally aged, domestic quality pork was destined for the domestic market, consumer scores increased significantly (P<0.05). No effect of information was observed on the perception of the 'chilled' export quality meat, perhaps a consequence of the high sensory quality observed prior to labelling.     

Indoor fattening of lambs raised on pasture. Part 1: Influence of stall finishing duration on lipid classes and fatty acids in the longissimus thoracis muscle

Forty male Ile-de-France lambs (10 blocks of 4 homologous lambs) were used to study the effects of four feeding systems on muscle fatty acids (FA): raising and finishing on cool-season grasses (G), raising on the same grasses and stall-finishing, indoors, on concentrates and hay, respectively, for 22 (GSS) or 41 days (GSL), and stall-feeding indoors on concentrates and hay during both growing and finishing periods (S). Twenty-four lambs only (6 blocks) were retained for comparison of growth performances, lipid content in the longissimus thoracis muscle (LT) and their FA composition according to treatment. The 16 other lambs (4 blocks) were removed from the comparison, due to a large spread in the growth of the lambs towards the end of the trial. No significant effects of treatment were seen on the rate of growth (221, 228, 243 and 245±SE 8.0g/d, respectively, for G, GSS, GSL and S groups), and the lipid contents of the LT (2.22, 2.16, 2.17 and 2.52±SE 0.11g/100g fresh tissue). Grazing, lowered n-6 PUFA (polyunsaturated fatty acids), and increased n-3 PUFA and C18:2 c9t11 (conjugated linoleic acid cis9, trans11) compared to concentrate feeding. The main effects of grazing were not removed by a short period of finish indoors on concentrate (GSS group), but C20:4 n-6 and C22:6 n-3 contents achieved the lowest contents in this group, with significant differences from the values observed for GSL and S groups (C20:4 n-6) or from the three other groups (C22:6 n-3). After a longer period of finish on concentrate (GSL group), C18:3 n-3 (linolenic acid), C18:2 c9t11 and long chain (LC) n-3 PUFA were brought to the levels observed in the S group. In terms of adequacy for human health, the C18:2 n-6/C18:3 n-3 ratios were favourably low in the four groups (2.6, 3.6, 4.9 and 5.2±SE 0.7, respectively, for G, GSS, GSL and S groups), the level observed in the case of G group being significantly lower than for the three other groups and the level observed for GSS group being significantly lower than for the GSL and S groups.     

Effect of Brussels sprouts and inulin/rape seed cake on the sensory profile of pork M. longissimus dorsi

The objective of the present study was to evaluate the influence of two diets containing either Brussels sprouts or inulin/rape seed cake, compared with a standard diet (control) for slaughter pigs on flavour and odour attributes and sensory profile of cooked pork. Three weeks prior to slaughter 24 female pigs were allocated to three diets: (1) a standard grower-finishing diet (control) for slaughter pigs containing barley, wheat and soy-bean meal, (2) the control diet containing 11 energy percent Brussels sprouts and (3) a diet containing 25% inulin and 55% rape seed cake. The odour and flavour of the cooked meat from inulin/rape seed cake-fed pigs differed significantly from the other two diets, showing reduced meat odour, increased pig and acrid odour, increased pig flavour, reduced fresh flavour and total impression. Meat from the Brussels sprouts-fed pigs deviated only slightly from the control-fed pigs.     

Influence of vacuum or high-oxygen modified atmosphere packaging on quality of beef M. longissimus dorsi steaks after different ageing times

The objective of the study was to determine if beef quality parameters differ between steaks in modified atmosphere packaging (MAP; 80% O₂ and 20% CO₂) and in vacuum packaging. Both M. longissimus dorsi (LD) from ten young bulls were cut in steaks day 3 postmortem and frozen either directly or after storage for 5 or 15 days in MAP and/or vacuum. The parameters studied were Warner Bratzler shear force, colour stability, α-tocopherol content, protein oxidation, water holding capacity and sensory attributes. Steaks stored in MAP had higher shear force than steaks stored in only vacuum at all ageing times. Tenderness and juiciness were negatively affected by storage in MAP. Ageing in MAP induced higher levels of metmyoglobin compared with vacuum ageing. In conclusion, high-oxygen MAP negatively influenced shear force, thawing loss, α-tocopherol content and colour stability, as well as the sensory attributes tenderness, juiciness and to some extent meat flavour.