Comparison of otolith and scale readings for age and growth estimation of common dentex Dentex dentex.

Three methods of age estimation were compared for Dentex dentex. Based on sectioned otoliths, scales appeared to be relevant only up to 5 years and whole otoliths up to 12 years. The maximum estimated age was 36 years, which constitutes to date the oldest age reported.

Sarcomere length determination using front-face fluorescence polarization.

Tryptophan is the major intrinsic fluorophore in muscle and is a constituent of proteins that have two preferential alignments both parallel and perpendicular to muscle fibre direction. A simple theoretical model and an experimental method based on front-face fluorescence polarization technique for tryptophan fluorescence anisotropy measurements were used for the estimation of post-rigor sarcomere length in beef in the range 1.6-3.4µm. Fluorescence anisotropy and structure-related model variables displayed changes in cold-shortened samples compared with normal and stretched ones. The anisotropy of contracted samples was lowered by misalignment of fibres in the sample. This method can therefore be used for in-line detection of cold shortening which has meat toughness as a consequence.

Sonoelasticity to monitor mechanical changes during rigor and ageing.

We propose the use of sonoelasticity as a non-destructive method to monitor changes in the resistance of muscle fibres, unaffected by connective tissue. Vibrations were applied at low frequency to induce oscillations in soft tissues and an ultrasound transducer was used to detect the motions. The experiments were carried out on the M. biceps femoris muscles of three beef cattle. In addition to the sonoelasticity measurements, the changes in meat during rigor and ageing were followed by measurements of both the mechanical resistance of myofibres and pH. The variations of mechanical resistance and pH were compared to those of the sonoelastic variables (velocity and attenuation) at two frequencies. The relationships between pH and velocity or attenuation and between the velocity or attenuation and the stress at 20% deformation were highly correlated. We concluded that sonoelasticity is a non-destructive method that can be used to monitor mechanical changes in muscle fibers during rigor-mortis and ageing.

Influence of season and host age on wild boar parasites in Corsica using indicator species analysis.

The indicator value (Ind Val) method which combines measures of fidelity and specificity has been used in a study on wild boar parasites in Corsica during 2001-2003. Because of its resilience to changes in abundance, IndVal is a particularly effective tool for ecological bioindication. The Ind Val method showed how season can influence the occurrence of parasite species in the wild boar, and also identified parasites as bioindicators relative to host age. The randomization test identified five parasite species having a significant indicator value for the season (the ticks, Hyalomma aegyptium and Rhipicephalus sanguineus, the louse, Haematopinus suis and the nematodes Globocephalus urosubulatus and Ascaris suum and two indicator species of an age class (the nematodes G. urosubulatus and Metastrongylus sp.). Data on species composition and infection levels would help improve the monitoring and management of parasitism in Suidae populations.

Measuring of viscoelastic properties of homogeneous soft solid using transient elastography: an inverse problem approach.

Two main questions are at the center of this paper. The first one concerns the choice of a rheological model in the frequency range of transient elastography, sonoelasticity or NMR elastography for soft solids (20-1000 Hz). Transient elastography experiments based on plane shear waves that propagate in an Agar-gelatin phantom or in bovine muscles enable one to quantify their viscoelastic properties. The comparison of these experimental results to the prediction of the two simplest rheological models indicate clearly that Voigt's model is the better. The second question studied in the paper deals with the feasibility of quantitative viscosity mapping using inverse problem algorithm. In the ideal situation where plane shear waves propagate in a sample, a simple inverse problem based on the Helmholtz equation correctly retrieves both elasticity and viscosity. In a more realistic situation with nonplane shear waves, this simple approach fails. Nevertheless, it is shown that quantitative viscosity mapping is still possible if one uses an appropriate inverse problem that fully takes into account diffraction in solids.

Perimysial collagen crosslinking and meat tenderness in Belgian Blue double-muscled cattle.

The relationship between intramuscular collagen and five collagen crosslink concentrations, and the tenderness of meat from Belgian Blue normal, heterozygous double-muscled (DM) and homozygous DM cattle was investigated using M. semitendinosus (St) and M. gluteobiceps (Gb). The histidinohydroxymerodesmosine (HHMD) concentration (per mol collagen) in St was less in DM animals than normal animals. Concentrations (per gram of wet meat) of HHMD and Erlich chromogen (EC) in Gb, and HHMD, EC, dihydroxylysinorleucine (DHLNL) and hydroxylysinorleucine (HLNL) in St were also lower in DM animals than normal animals. Shear force of raw meat was significantly greater in normal animals than DM for both muscles; cooked meat shear force was greater in the normal animals for the Gb muscles only, showing a good correlation with sarcomere length. Most correlations between shear force and collagen or crosslink concentrations were not significant and those that were highly significant were generally weak.

Effect of nutritional factors on biochemical, structural and metabolic characteristics of muscles in ruminants, consequences on dietetic value and sensorial qualities of meat.

Ruminant meat is an important source of nutrients and is also of high sensory value. However, the importance and nature of these characteristics depend on ruminant nutrition. The first part of this review is focused on biochemical and dietetic value of this meat. It offers a panel of quantitative and qualitative contributions, especially through its fatty acids characteristics. Since saturated and trans-monounsaturated fatty acids are considered as harmful to human health, their amount in muscles can be reduced by increasing the proportions of dietary polyunsaturated fatty acids (PUFA) absorbed by the animals. On the contrary, some fatty acids (n-6 and n-3 PUFA, conjugated linoleic acid) specifically incorporated in muscle tissues would play a favourable role in the prevention or reduction of major diseases in human (cancers, atherosclerosis, obesity) and therefore be recommended. The second part of this review treats different aspects of the sensorial qualities of meat. Skeletal muscle structure and its biochemical components influence muscle transformation to meat and sensorial qualities including tenderness, colour, flavour and juiciness. This paper shows how nutrition can influence, in ruminants, metabolic activity as well as muscle structure and composition, and thereby affect meat quality.

Effects of age and sex on the structural, chemical and technological characteristics of mule duck meat.

1. The aim of the study was to analyse the effect of age and sex on the chemical, structural and technological characteristics of mule duck meat. 2. Ten males and 10 females were weighed and slaughtered at 8, 10, 11, 12 and 13 weeks of age. Weight, pH value, colour, tenderness and juice loss of breast muscle were determined. 3. The activities of 3 enzymes (citrate synthase, beta-hydroxyacyl CoA dehydrogenase, lactate dehydrogenase) which indicate muscular metabolic activity were assayed. 4. Chemical composition (moisture, lipids, proteins, minerals, lipid and phospholipid classes, fatty acid composition) of breast muscle was analysed. 5. Fibre type, fibre type percentage and cross-sectional areas were determined using histochemistry and an image analysis system. 6. For growth performance and muscular structure, the ideal slaughter age of mule ducks is 10 weeks of age. Chemical and technological analysis indicated that muscular maturity in Pectoralis major was reached at 11 weeks of age, but, at this age, breast lipid content is high. Moreover, after 10 weeks of age, food costs rapidly increased. 7. Lastly, sexual dimorphism for body weight is minor. In this study, at any given age, no significant differences between males and females were shown. Thus, it is possible to rear both sexes together and to slaughter them at the same age.

Effects of the halothane genotype and slaughter weight on texture of pork.

The objective of this study was to investigate the effects of the halothane (HAL) genotype, slaughter weight (SW), and the HAL x SW interaction on compositional and textural traits of raw and cooked pork. Pigs were bred to exhibit one of the three HAL genotypes (NN, Nn, and nn) with otherwise equivalent genomes. The nn halothane reactors are known to typically produce PSE pork, whereas NN pigs do not typically produce PSE pork. Pietrain x Large White gilts and boars, all with verified Nn genotype (by DNA test), were mated to obtain F2 littermates of the three HAL genotypes. These pigs were slaughtered at either 101 +/- 3 ("light") or 127 +/- 3 ("heavy") kg BW and were evaluated for longissimus muscle traits. The pH at .5 h after death (pH1) was 6.35, 6.13, and 5.68 in NN, Nn, and nn pigs, respectively. Sarcomere length was greater in nn than in NN and Nn pigs (1.94 vs 1.83 and 1.85 microm, respectively). Mechanical resistance was higher in nn than in NN pigs for both raw and cooked meat. Meat from nn pigs was judged by a trained panel to be less rough, more cohesive, harder, more fibrous, less granular, more elastic, and less easy to swallow than meat from NN pigs. For most traits under study, the heterozygotes were intermediate between the homozygotes but closer to NN than to nn pigs. Muscle from heavy pigs had longer sarcomeres and less moisture than muscle from light pigs. The n allele of the HAL gene unfavorably affects pork texture, and this effect is maintained throughout the range of 101 to 127 kg BW.

Treadmill running starting 3 months after orchidectomy restores femoral bone mass in rats.

The present study was designed to provide data on the effects on femoral bone of endurance training starting only 3 months after orchidectomy in rats. A total of 70 Wistar male rats were used at 8 weeks of age. On day 0 of the experiment, 10 rats were killed by cervical dislocation to be used as first controls. Among the 60 other animals, half was surgically castrated (CX) or sham operated (SH). On day 90, 10 CX and 10 SH were killed and used as intermediary controls (ICX and ISH). Among the other 20 CX and 20 SH, 10 within each group (CXE, SHE) were selected for treadmill running (60% maximal oxygen uptake, 1 h x day(-1), 5 days x week(-1) for 12 weeks). The 20 other rats were used as sedentary controls (CXR, SHR) and killed (as runners) on day 180. On day 90 femoral bone density (BMD) and mineral content (BMC) were lower in ICX than in ISH. On day 180 total femoral BMD was lower in CXR than in CXE. Simultaneously metaphyseal femoral BMD was lower in CXR than in CXE, SHR or SHE. Furthermore, at that time, no significant difference concerning BMD and BMC was observed between SHR and CXE. This would indicate that treadmill running starting only 3 months after orchidectomy is able to restore BMD and BMC to control values, mainly by inhibiting bone resorption (as shown by decreased urinary deoxypyridinoline excretion in CXE) without decreasing osteoblastic activity (evaluated by plasma osteocalcin concentration).

Effects of high-intensity high-frequency ultrasound on ageing rate, ultrastructure and some physico-chemical properties of beef.

High-intensity and high-frequency ultrasound was tested for its ability to accelerate meat ageing and increase beef tenderness. Samples (≈50g) of semimembranosus muscles from 8 cull cows were assigned to ultrasonic treatment (2.6MHz; 10W/cm(2); 2 ×15s) either pre-rigor (day 0, pH 6.2) or post-rigor (day 1, pH 5.4). When applied pre-rigor, ultrasound induced a slight delay in rigor mortis onset, a stretching (12-15%) of the sarcomeres (p<0.05), an ultrastructural alteration in the Z-line region and an immediate increase (around 30%) in the release of calcium in the cytosol (p<0.05). However, no conclusive effect on meat ageing rate was observed. Post-rigor ultrasonic treatment did not induce any structural modification but slightly improved the ageing index after 6 days (p<0.05). However, no improvement in the final (day 14) ageing index was observed compared to the controls. As ultrasound had also no effect on the thermal stability of collagen, at both postmortem times, no improvement in meat tenderness can be expected under the conditions used.

Effect of pelvic suspension and cooking temperature on the tenderness of electrically stimulated and aged beef, assessed with shear and compression tests.

Electrically stimulated carcass sides of young bulls were suspended at 1 hr post mortem from the aitch bone (pelvic suspension; PS) and Achilles tendon (AT), respectively. After an ageing period of 14 days at 3 °C, shear force (SF) and compression (20 and 80% compression) tests of the Mm. longissimus lumborum et thoracis (LO) and semimembranosus (SM) were conducted in raw muscle and after heating for 1 hr at 55, 60, 65, 70 and 80 °C. Collagen content was higher in SM than in LO, while sarcomere length (SL) of raw muscle were 1.75 and 1.78, for LO and SM. In comparison with the AT-side, PS increased SL by 21 and 47% and cooking loss (at 80 °C) by 2 and 6% for LO and SM, respectively. Drip loss of whole muscles from the PS-side during the ageing period tended to be lower (n.s.). Over the whole cooking temperature range, SF-values were relatively high for the SM in comparison with LO. For both muscles from the AT-side, the lowest SF-values were observed at 60 and 65 °C. The PS-treatment resulted in higher SF- values for raw muscle and after cooking at low temperatures (55 and 60 °C), particularly in the SM. In the intermediate temperature range (65 and 70 °C), PS had no significant effect, while in the higher temperature range (80 °C), SF-values were lower in the PS-side. Similar tendencies were observed in the LO, although the lower SF-values for the PS-side were observed already at 60 °C. In non-destructive compression (20%), there was a gradual increase in stress values with increasing cooking temperature. In comparison with the AT-side, the PS treatment resulted in the LO in similar or higher, and in the SM in lower stress values. With destructive compression (80%), PS resulted in SM in higher stress values in raw muscle and at 55 °C, in accordance with the SF-values. It is suggested that the higher SF- and 80% compression values in raw muscle and at low cooking temperatures, are caused by an increase in collagen strength due to a change in the direction and spatial organisation of the collagen fibres as a result of stretching of the muscle. This study demonstrates that the relative contributions of the collagen and myofibrillar components to the mechanical assessed toughness, as well as the effect of pelvic suspension, is dependent of muscle, cooking temperature and the mechanical test applied.

Influence of treadmill running on femoral bone in young orchidectomized rats.

Forty 6-wk-old male Wistar rats weighing 308 +/- 24 g were divided into two groups. On day 0, the 20 animals in one group were surgically castrated and the other group was sham operated. Within each group, 10 rats were selected for treadmill running (60% maximal O2 consumption, 1 h/day, 6 days/wk for 15 wk). The 20 sedentary rats were used as controls. At the time the rats were killed (day 105), running had no significant effect on femoral mechanical properties either in castrated or in sham-operated rats. Femoral bone density was lower in orchidectomized than in sham-operated rats. Nevertheless, it was higher in exercised than in sedentary rats. Femoral Ca content paralleled changes in bone density. Treadmill running had no significant effect on plasma osteocalcin concentration but inhibited the increase in urinary deoxypyridinoline excretion observed in castrated rats. Image analysis (measured at the distal femoral diaphysis) revealed that these effects mainly resulted from decreased trabecular bone resorption in castrated exercised rats.

Effects of high pressure on meat: A review.

Extensive investigations in the last decade have revealed the potential benefits of high pressure processing (100-800 MPa) for the preservation and modification of foods. Simultaneously, a few pressurised foods have become commercially available in Japan, Europe and the USA. In the present review, the basic principles underlying the effects of high pressure on food constituents and quality attributes are first presented. Recent data concerning the following specific effects of high pressure on muscle and meat products are then reported and discussed: changes in muscle enzymes and meat proteolysis; modifications in muscle ultrastructure; effects on myofibrillar proteins; meat texture and pressureassisted tenderisation processes; pressure-induced gelation and restructuring of minced meat; changes in myoglobin and meat colour; influence of pressure on lipid oxidation in muscle; high pressure-inactivation of pathogenic and spoilage micro-organisms in meat; combined high pressure-moderate temperature 'pasteurisation' of meat products.

Effect of duration of feed withdrawal and transportation time on muscle characteristics and quality in Friesian-Holstein calves.

Twenty-week-old Friesian-Holstein calves were used to assess the influences of the duration of feed withdrawal before transport (1 or 11 h) and of transport time (1 or 11 h) on carcass and muscle characteristics and meat sensory qualities. One hundred twelve calves were used for live weight and carcass measurements, following a 2 x 2 factorial design (28 replicates). Twelve calves were randomly selected in each treatment group to examine muscle characteristics and sensory quality of longissimus lumborum (LL) and semimembranosus (SM). Long transport (11 h) increased loss in live weight (P < .001) and dressing percentage (P < .001). Feed withdrawal for 11 h also increased dressing percentage (P < .001). Long transport resulted in decreased liver weight (P < .05), glycolytic potential (P < .01), and pH at 4 h postmortem (P < .05) in the LL. Drip loss, compositional traits, cooking loss, and sarcomere length in the LL, as well as drip loss, pH values, compositional traits, cooking loss, and sarcomere length in the SM, were unaffected by the treatments. However, long transport decreased tenderness score in the LL (P < .05) and SM (P < .01). It also increased myofibrillar resistance (P < .001) in the latter muscle. The results demonstrate an unfavorable effect of long transport on the sensory quality of veal. This effect cannot be explained on the basis of differences in pH values and(or) compositional characteristics.

Mechanical properties of meat.

Determination of meat mechanical properties is still usually performed under empirical conditions, using tests which have been developed many years ago. This paper discusses the limitations of these methods. It also reviews recently developed research which has been focused on a more analytical approach to mechanical tests performed in closely controlled conditions. The objectives of these investigations are on the one hand to obtain specific properties of the myofibre and connective tissue structures involved in meat toughness and on the other hand to understand the fracture mechanisms involved in the perception of texture. Due to the anisotropic and composite nature of meat, attention has been focused on the influence of the direction and amplitude of strains to be used for the characterisation of myofibres and connective tissue, respectively. These strain conditions are linked to the contraction and stretching state of each of these structures. Indeed, whatever the type of deformation (shear, compression or tension), myofibre resistance can be determined under low strain conditions as long as collagen fibres in the connective tissue remain in a more crimped state than myofibres, i.e. in raw or slightly cooked meat of normal sarcomere length. On the contrary, determination of connective tissue resistance has, up to now, only been obtained using large strain tests. Contraction of collagen fibres induced by cooking makes the separate analysis of meat structures more difficult, but this can partially be overcome by applying mechanical tests in different strain directions. However, the role of the spatial distribution of connective network on the mechanical properties of meat still remains largely unknown. Image analysis and ultrasonic methods, currently developed to study this problem, are briefly presented.

Performance, muscle composition and meat texture in veal calves administered a ß-agonist (clenbuterol).

The effect of clenbuterol administration on performance, muscle composition and meat texture was studied in veal calves. Three groups, of ten animals each, were assigned to the three following treatments for 27 days: control, administration of 0·3 and 1·0 ppm in the feed (dry matter basis). After a 14-day withdrawal period, the animals were slaughtered, and three muscles were sampled (M. longissumus thoracis; M. triceps brachii caput longum; M. rectus abdominis). During the period of clenbuterol administration, the treated calves exhibited a higher daily liveweight gain (DLWG) and a higher feed conversion efficiency (FCE) compared to those of the control calves, but these effects were reversed during the subsequent withdrawal period. At slaughter, the overall DLWG, FCE and carcass weight were similar in the three treatments, but the dressing percentage in the clenbuterol-treated calves was up to 5·7 points higher than that of the control calves. In the muscles studied, the clenbuterol had little effect on pH, sarcomere length, dry matter and nitrogen contents, collagen heat stability (solubility, isometric tension) or cooking loss; but it markedly reduced the content of lipids, collagen and haem pigments. The clenbuterol also affected myofibrillar strength after ageing, measured either on raw meat or on cooked meat. This was particularly evident in cooked meat which showed up to a two-fold increase in mechanical parameters (maximum stress, compression modulus) after the clenbuterol treatment. No dose effect was detected except for the mechanical parameters. It was concluded that clenbuterol administration affects, meat in two opposite ways, viz. a marked toughening effects, due to a reduction in the muscle ageing rate, that is not compensated by a concomitant tenderizing effect (through a decrease in the intramuscular collagen content).

Effect of feed protein on carcass composition and meat quality in steers.

Forty-five Charolais steers were fed one of four experimental regimes containing maize silage and maize grain supplemented with either protected soyabean-rapessed meal or linseed meal. The first three regimes were formulated to supply the same energy and different protein levels with soyabean-rapessed meal: low (L-SRM), medium (M-SRM) and high (H-SRM). The fourth regime consisted in feeding the same amount (kg/day) of linseed meal as that of soyabean-rapessed meal in the H-SRM regime (LSM). As the protein level increased from L-SRM to H-SRM, the daily weight gain of steers increased and the carcass composition was changed towards higher muscle and lower fat proportions. Though the actual supply of feed protein by regime LSM was close to that achieved with M-SRM, the effect of linseed meal supplementation on weight gain and carcass composition was comparable to that obtained by feeding the high protein level (H-SRM). The dry matter content increased and the heme pigments and lipids contents decreased in longissimus thoracis muscle as the protein supply increased from the low to the high level. Again the amplitude of the differences in meat quality with L-SRM were similar in H-SRM and LSM. Muscle colour, connective tissue and mechanical strength remained practically unaffected by the protein treatments. However, meat was scored less tender in H-SRM and less juicy in treatment LSM than in treatment L-SRM. The results obtained with linseed meal suggest a specific effect of type of feed protein on beef carcass composition and meat quality.

Influence of technological parameters on the structure of the batter and the texture of frankfurter type sausages.

The aim of the study was, on the one hand, to determine the relationships between various technological factors, the structure of the batters and the texture characteristics of frankfurter type sausages, and, on the other, to define the possibilities of realizing a reference scale for texture. The addition of sodium chloride in the 0-2% range induces a large increase (60%) in the cooking yield, a decrease in the specific gravity and an increase in the viscosity of the batter determined indirectly through the evolution of the product temperature during chopping. These variations together, give a 30% decrease in the mechanical firmness and a 100% and 90% increase in the juiciness and elasticity of the final products, respectively. However, beyond 2%, sodium chloride does not induce any significant effect on these characteristics. The addition of caseinate in a 1-3% range induces a degassing of the batter and a 10-37% decrease in the water losses during cooking. The higher the caseinate content in the 0-6% range, the larger the rise in the batter temperature during chopping. Sausages are also considered harder (+22%) and less juicy and elastic (-50%) when caseinate content increases. Addition of 0·1-0·5% polyphosphates and chopping under vacuum (0·2 atm) induce variations in the cooking yield, +3% and -1%, respectively, but have no influence on the texture of the final products. Modifications of all these technological parameters induced variations by a factor of 2 in the different mechanical parameters and in parallel differences of 1-2 points on a 6 point scale for sensory characteristics.