Halothane genotype and pork quality. 3. Comminuted meat products derived from the three halothane genotypes

The effect of the halothane gene on cured meat products was investigated using the meat from 60 Landrace×Large White pigs of known halothane genotype (NN=25, Nn=19, nn=16). Results for the two types of fresh sausage manufactured (with and without rusk) indicated that the NN pigs (15.7%) had lower total moisture losses (P<0.05) compared to the nn pigs (18.9%), with Nn being intermediate (17.4%) for the sausage without rusk. Where rusk was added, there were no significant differences between genotypes for moisture losses (NN=12.6%, Nn=13. 0%, nn=14.2%). Taste panel evaluations of the fresh sausages made without rusk indicated no genotypic influence for juiciness, however the sausage made with the rusk was judged the juiciest for the nn genotype, with Nn being intermediate and NN the least juiciest. The smoking and cooking losses during manufacturing of the emulsion product (vienna) indicated that the nn genotype (12.5%) had significantly (P<0.05) higher total losses than the Nn genotype (11. 3%), with NN being intermediate (12.4%).     

Halothane genotype and pork quality. 1. Carcass and meat quality characteristics of three halothane genotypes

The carcass and meat quality characteristics of three halothane genotypes in pigs were evaluated. Sixty crossbred Landrace×Large White pigs (NN=25, Nn=19, nn=16) of ±86 kg live weight were slaughtered, the carcasses chilled for 24 h at 2°C, certain carcass and meat quality traits determined and the shoulder and leg cuts deboned and cut into primal cuts. Dressing percentage of the Nn pigs was higher (P<0.05) than that of the NN and nn pigs. Carcass length was the longest (P<0.05) for the nn pigs. Midline fat measurements as well as measurements at the 2nd-3rd last rib (45 mm from the midline) indicated that the nn pigs had less fat (P<0.05) and a larger eye muscle width (P<0.05), depth (P<0.001) and area (P<0.001) than the NN or Nn pigs. This resulted in the nn pigs having the highest (P<0.05) percentage predicted carcass lean content. Fat, bone and lean yield of the shoulder identified the nn pigs with the least bone (P<0.05) and fat (P<0.001) and the highest lean yield (P<0.05), expressed as a percentage of total shoulder weight. Yield from the legs identified the nn pigs as having the lowest fat (P<0.001) and highest lean (P<0.05), expressed as a percentage of total leg weight. The primal lean cuts (topside, silverside, thickflank and rump) from the legs showed that the nn pigs had the highest values (P<0.05) for lean as a fraction of cold carcass weight. This resulted from the higher weight of these cuts (P<0.05) in the nn pigs. Calculation of bone yield in the legs showed that the femur weights were highest (P<0.05) for the Nn pigs, also when expressed as percentage of leg weight (P<0.05) and as a fraction of cold carcass weight (P<0.05). Comparison of meat quality traits show that the nn pigs had poor quality with regard to pH(45) (P<0.001), pH(24) (P<0.05), drip loss (P<0.001) and reflectance values (P<0.05).     

Halothane genotype and pork quality. 2. Cured meat products of three halothane genotypes

The effect of the halothane gene on cured meat products was investigated using the meat from 60 Landrace×Large White pigs of known halothane genotype (NN=25, Nn=19, nn=16). The backs and hams were used to prepare cured, smoked bacon and canned hams. Initial bacon gain in pumped weight was significantly higher (P<0.001) for the NN (15.2%) and Nn (14.9%) compared to the nn pigs (8.9%). Similarly, the total gain in bacon yield was the highest for the Nn (11.5%) and NN pigs (10.0%), and significantly higher (P<0.05) than the bacon from nn pigs (3.4%). Differences between sexes were not significant. Canned hams (no phosphate) from the NN genotype had a significantly (P<0.001) lower percentage cooking loss (27.9%) compared to the Nn (30.1%) and nn pigs (31.1%), which did not differ statistically. Although addition of phosphates (0.3% on final product) led to a decrease in percentage cooking loss, the genotypes gave a similar response, with the NN genotype having 13.8% cooking loss, significantly lower (P<0.001) than the Nn (16.9%) and nn genotypes (17.7%). The results indicate reduced product quality with the inclusion of the halothane gene.     

Sensory characteristics of cooked pork loin as affected by nucleotide content and post-mortem meat quality

Muscle longissimus dorsi excised at 2hr post mortem was utilised to study the effect of post-mortem meat quality, and their content of nucleotide metabolites, on the sensory characteristics of cooked loin. Four different post mortem meat qualities were defined: pale soft exudative (PSE), red soft exudative (RSE), red firm non-exudative (RFN) and dark firm dry (DFD). The DFD meat quality class showed low sour and salty tastes and a high sweet taste, low astringency and high juiciness and tenderness, giving the best overall quality. On the other hand, the RSE quality class produced a meat with a low juiciness and high hardness, and a low overall quality although these differences were not significant (p<0.05) against RFN and PSE meats. The effect of nucleotide metabolite contents on the sensory meat properties were most significant on taste although, the different meat qualities were only significantly different (p<0.05) in the content of hypoxanthine, guanosine, GDP and IDP.     

Muscle glycogen level and meat quality in pigs of different halothane genotypes

The halothane genotype of 22 Polish landrace pigs was determined using halothane test and blood typing. Eight homozygous normal (NN), eight hetero-zygotes (Nn) and six homozygous recessive (nn) were identified. The levels of glycogen and lactate were measured in biopsy samples taken from the longissimus lumborum using a shot biopsy technique. pH (pH(1)) and IMP/ATP ratio (R) were determined at 30 min after slaughter, while pH, meat colour and water holding capacity were determined on the day after slaughter. The halothane genotype did not affect intra vitam glycogen level. The nn pigs had a higher R value and lower pH(1) than both Nn and NN animals. Heterozygous animals were intermediate between both homo-zygotes for biopsy lactate level and meat colour. The lactate content of biopsy samples was significantly correlated with pH(1) (r = -0·68; P < 0·01), R (r = 0·68; P < 0·01), meat colour (r = 0·57; P < 0·01) and water holding capacity (r = 0·45; P · 0·05).     

Carcass characteristics and meat quality of halothane negative and halothane positive pietrain pigs

One hundred and seventy-six Pietrain pigs were tested for halothane sensitivity by means of a 5-min halothane anaesthesia in two experiments. One hundred and twenty were halothane negative (HN) and 56 were halothane positive (HP). In one experiment pigs were slaughtered under commercial (stress) conditions; in the other experiment pigs were killed under minimal stress conditions.

The carcasses of HP pigs were meatier and shorter and contained 2·2% more muscle than the carcasses of HN pigs.

Halothane positive pigs gave a meat of poorer quality, as assessed in the fresh state. When the pigs were slaughtered under commercial conditions, hams from HP pigs were not inferior in curing ability and had a higher total processing yield of Paris ham due to their higher trimming yield. When the pigs were killed under minimal stress conditions, there was no difference in the total processing yield betwen HN and HP pigs, because the technological yield was markedly reduced in HP pigs. However, in both cases, HP pigs produced more cooked ham per pig.

It is suggested that different physiological mechanisms may account for either PSE (pale soft exudative) or DFD (dark firm dry) meat. The former is the consequence of an excessively high rate of post mortem glycolysis which is clearly manifest in HP pigs when they are killed under minimal stress conditions and the latter appears to be unrelated to halothane sensitivity as the ultimate pH of HP and HN pigs is similar when the animals are slaughtered under stress conditions.     

Texture and rheological properties of meat from pigs of different halothane genotypes

The effects of halothane genotype (NN, Nn and nn) in pigs on meat texture, rheological properties, fibre diameter, area of intramuscular fat, pH, colour, drip loss, cooking loss and yield of cooked and of smoked loin were examined. Cooked and smoked meat of NN pigs exhibited lower hardness, gumminess, chewiness, elasticity moduli, greater cohesiveness and a longer relaxation time compared to meat from pigs with genotype Nn or nn. Meat from pigs of the nn genotype exhibited the greatest hardness and elasticity, the shortest relaxation time and the lowest viscosity and cohesiveness, while meat from genotype Nn was intermediate regarding these parameters. Significant correlations were found between parameters of texture, and rheological properties and pH, structure, drip and cooking loss. © 1998 SCI.     

Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca²⁺ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca²⁺ specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca²⁺ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice.

Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH₁ and fibre optic probe (FOP) measurements.

The extent of deterioration (%) in Ca²⁺ accumulation showed high correlations with fluid (r = −0·861) and pH (fluid) (r = −0·831) in the biopsy LD samples, and with pH₁ (r = 0·663), FOP (r = −0·812), and drip (%) loss (r = −0·777) in the post-mortem LD samples.     

Effects of dry-ageing on pork quality characteristics in different genotypes

Presumably, dry-ageing enhances flavour attributes of meat by surface desiccation to increase and modify fatty acid content and other organoleptic molecules. However information regarding dry-ageing of fresh pork is limited. To examine the effects of dry-ageing on pork quality, Large White (LW, n = 24) and Large White × Duroc (Duroc, n = 24) barrows were slaughtered and three longissimus thoracis et lumborum sections from each side of the carcass were wet or dry-aged for 2, 7 or 14 d. Dry-aged meat had lower (P < 0.001) moisture and higher (P < 0.001) protein content due to higher purge losses (P < 0.001) when compared with wet aged meat. However no dry-ageing effect (P > 0.05) was observed on sensory characteristics. The increase in the duration of ageing decreased moisture content and drip loss and increased (P < 0.001) protein content, purge loss and L*, chroma and hue values. These changes were more accentuated in dry-aged meat (P < 0.01). Days of ageing dependent increases (P < 0.001) were observed for instrumental and sensory tenderness and juiciness in both ageing types. Moreover, meat from Duroc barrows had lower (P < 0.001) moisture and protein content, and higher (P < 0.01) fat content, L* and hue values. Instrumental and sensory tenderness, juiciness and flavour were higher (P < 0.01) in meat from Duroc than LW barrows. Increases (P < 0.01) in flavour intensity and decreases in off-flavour of meat from LW barrows were greater (P < 0.05) in d 7 than in d 14. Therefore the duration of ageing affected most quality and sensory characteristics, while the changes to quality attributes of dry versus wet-aged pork were attributable to the differences in shrink losses in the present study.     

Muscle fibre characteristics and metabolic response at slaughter in pigs of different halothane genotypes and their relation to meat quality

Muscle samples for histochemical and biochemical analyses were taken immediately at slaughter from M. longissimus dorsi of pigs with different halothane genotypes (NN and nn). Fibre type composition was similar between groups but the nn-genotype had larger mean fibre areas and lower capillary density than the NN-genotype. At exsanguination the nn-genotype had lower muscle pH (pH(e)), higher lactate and ammonia and lower glycogen and phosphagen (ATP and CP) concentrations and twice as many glycogen-depleted type IIA and IIB fibres as compared with the NN-genotype. Muscle pH(e) was correlated positively to capillary density, glycogen and phosphagen concentrations and negatively to mean fibre area, ammonia and lactate concentrations. Ammonia concentrations were correlated negatively to ATP concentrations and positively to the percentage of glycogen-depleted IIB fibres. The highest reflectance and drip loss values were seen in the nn-genotype. The reflectance values were correlated positively to the percentage of glycogen-depleted type IIB fibres in muscle and the values for drip loss were correlated negatively to pH(e). These data show that fibre size and capillary density in muscle seem to be important factors that influence the metabolic response at slaughter and thus meat quality.     

Sensory and meat quality traits of pork in relation to post-slaughter treatment and RN genotype

The effects on eating quality and meat quality of two different forms of post-slaughter treatment, performed in an abattoir, were studied in carriers and non-carriers of the RN(-) allele. Carcasses were subjected to rapid and slow chilling, and pelvic and Achilles suspension in a factorial experimental design. A temperature of 10?°C was achieved in the centre of M. longissimus dorsi (LD) within 3.5 h in rapidly chilled carcasses and within 8 h in slowly chilled carcasses. In deep M. semimembranosus (SM) a temperature of 10?°C was achieved within 11.5 h in rapidly chilled carcasses and within 14 h in slowly chilled carcasses. LD from slowly chilled RN(-) carriers suspended by the pelvis exhibited the greatest tenderness, while LD from rapidly chilled non-carriers suspended from the Achilles tendon exhibited the lowest tenderness. Pelvic suspension or slow chilling of non-carriers produced the same improvement in tenderness, and when combined the tenderness increased further. However, the tenderness of the RN(-) carriers was already high, and no significant improvement was seen following any of the studied post-slaughter treatments. Pelvic suspension prevented shortening of muscle fibres, as seen by longer sarcomeres in LD from pelvic-suspended sides. However, longer sarcomeres were associated with greater tenderness only in LD from non-carriers of the RN(-) allele. The presence of the RN(-) allele and a slow chilling regime increased the rate of pH decline in LD. Achilles suspension also increased the rate of pH fall in SM, in addition to the RN(-) allele and slow chilling. The overall tenderness of LD was mainly related to the course of pH decline during rigor; lower pH values between 3 and 7 h post-mortem contributing to greater tenderness. The myofibrillar length was predominantly related to RN genotype and was shorter in RN(-) carriers than in non-carriers. The RN(-) allele and slow chilling contributed to higher evaporation losses and RN(-) carriers exhibited increased frequency of PSE meat in the ham muscles. The use of pelvic suspension appears advantageous over slower chilling, since it improved tenderness without any negative influence on drip loss, evaporation or cooking loss.     

劣质猪肉的感官鉴别法

劣质猪肉不仅影响肉品的质量,而且严重危害食用者的身体健康.为了保证人民群众吃上健康无疫、色泽良好的肉品,笔者结合多年的工作实践经验,将劣质肉的感官鉴别要点介绍如下,以便大家快速准确的识别肉品质量,维护自身健康和经济利益.     

Sensory quality of meat from lambs fed garlic

The objective of this study was to determine whether the inclusion of garlic in a ration would have a negative impact on the flavour of lamb. The study used meat from 31 Merino wether lambs fed diets with varying levels of garlic (0%, 1.8% and 3.6%) for 10 weeks. Cooked samples of meat from the lambs were assessed for flavour and acceptability as lamb by an untrained consumer panel. There was no difference (P>0.05) between the treatments in flavour score, but the 3.6% garlic treatment group scored significantly higher in terms of acceptability as lamb (P<0.05) and was commented on positively by the panellists more frequently than the meat from any other treatment (P<0.05). These results suggest that the inclusion of garlic into the animals' feed did not have a negative impact on the flavour of the lamb and, at the high rate (3.6%), made the meat more acceptable to the panellists.     

Antioxidant, lipolytic and proteolytic enzyme activities in pork meat from different genotypes

Oxidative processes in meat lead to meat quality deterioration. Meat has endogenous antioxidants and prooxidants, but information on factors influencing the activity of antioxidant enzymes in meat is limited. Lipolytic and proteolytic enzymes are involved in important aspects of meat quality. Our objective was to find differences between five different genotypes on the activity of antioxidant, lipolytic and proteolytic enzymes in meat. Forty Psoas major muscles of females of five different pig genotypes were used, Pietrain, Landrace, Large-White, lberian, and lberian×Duroc. Pre slaughter conditions were similar for all the genotypes. After slaughter, muscles were vacuum packed and frozen at -20?°C until required. Differences between genotypes were found for the activity of catalase and SOD, while GSH-Px showed no differences. The highest differences between breeds were found for the lberian breed where catalase had the highest activity. Catalase activity also showed differences between the white pigs, with large values for LR and lower activities in P. There were no differences in neutral lipase activities between the different genotypes while acid lipase and phospholipase showed significant differences. The activities of cathepsin B and H were significantly lower for Iberian pigs compared with other breeds except LR, while the ratio of cathepsin B+L/cathepsin B was higher in Iberian. The differences between genotypes found in enzyme activities suggest some genetic effects on the antioxidant, lipolytic and proteolitytic activity of pork meat.     

Influence of meat exudates on the quality characteristics of fresh and freeze-thawed pork

The influence of the accumulated exudates released from pork loin of itself on the quality characteristics of fresh and freeze-thawed pork during cold storage was investigated. Pork loins were divided into four groups (fresh pork with exudates, fresh pork without exudates, freeze-thawed pork with exudates and freeze-thawed pork without exudates) and stored at 1.0 °C for 7 days. Exudate amount increased due to freeze-thawing and with storage, and most quality traits such as drip loss, cooking loss, tenderness, lightness, redness, and moisture content were affected by freeze-thawing (p < 0.05). Freeze–thaw increased drip loss but decreased moisture content, cooking loss, tenderness, lightness and redness of meat (p < 0.05). Microbial growth was solely affected by exudate removal and the removal of initial exudates decreased microbial growth (p < 0.05). Exudates were positively correlated with total protein content and total plate count but negatively correlated with pH and cooking loss. Therefore, removing meat exudates and avoiding freeze can slow down the quality deterioration of pork during cold storage.     

The relationship between carcass, meat and eating quality of three pig genotypes

The relation between the intrinsic carcass and meat quality and the organoleptical characteristics of three genotypes of pigs was studied. In total 411 pigs, consisting of 121 BL-genotype pigs, 115 hybrids (Seghers Hybrid) and 175 Large White-genotype pigs, were screened. Slaughter day and genetic background had a great impact on the intrinsic meat quality parameters. The factor 'slaughter day' implies the stunning method besides the total specific transport and slaughter conditions. Whatever the genetic background is, halothane susceptibility is obviously the crucial factor. Selection against the halothane gene positively influences the intrinsic and sensory meat quality parameters. This study also suggests that an increase in the intramuscular fat content, if desirable in the interest of the sensory meat quality, can be achieved without deterioration of the zoo-technical performance and the carcass quality of the pigs.     

Influence of porcine stress on blood composition and early post-mortem meat quality in pigs of different halothane genotypes

The purpose of this study was to investigate porcine stress, blood serum values and early post-mortem (pm) meat quality in pigs of unknown and known halothane genotype. Collection, transportation and slaughtering of the pigs were studied from the farm up to the carcass chilling (45 min pm). Reactors (nn) had the highest creative kinase (CK) activity. CK activity increased most prominently during transport in reactors, and at the abattoir in non-reactors (Nn or NN). The content of serum glucose was highest in non-reactors and lowest in non-carriers (NN, P<0·01). Serum glycerol level was highest in reactors and lowest in carriers (Nn, P < 0·05). Differences in serum lactate and pH values were not significant. Carriers had the highest and non-reactors the lowest carcass temperature, 0 min pm (P = 0·001). Temperature of non-reactors increased most rapidly (9·4%) and that of carriers increased most slowly (0·9%) during scalding. Reactors had the most rapid (3·1%) and carriers the slowest (0·3%) fall in carcass temperature between scalding and chilling. No significant differences were found between halothane genotypes in the rate of glycogen breakdown and lactate formation, 45 min pm. PSE (pH(1) ≤ 5·8) frequencies of reactors, non-reactors, non-carriers and carriers were 100·0, 14·3, 13·0 and 12·5, respectively.     

Prevalence and genotypes of Toxoplasma gondii in pork from retail meat stores in Eastern China

Pork is known as one of the most important sources of Toxoplasma gondii infection in China. In the present study, 416 fresh pork samples were collected from different locations of Anhui province, Eastern China. Tissue fluid ELISA was conducted to detect the antibodies to T. gondii. Real-time PCR and bioassay were performed to identify the presence of T. gondii DNA and viable parasites, respectively. Seventy-five out of 416 samples (18.03%) demonstrated real-time PCR positive reaction and 42 out of 416 samples (10.1%) showed tissue fluid ELISA positive reaction. One isolate (Tgpkfx171) was obtained through bioassay in mice from 14 samples that demonstrated both PCR and ELISA positive reaction. The isolate and seven positive DNA samples were genotyped using 9 PCR-RFLP markers including SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico. Among these, only the isolate and two positive DNA samples were genotyped with complete data for all loci, belonging to ToxoDB#9 (Chinese 1) and ToxoDB#213, respectively. This is the first report of the prevalence and genetic typing of T. gondii from pork in retail meat stores in China. The present results provide an accurate picture of the risk of exposure to T. gondii in retail pork in China.     

Consumers' expected quality and intention to purchase high quality pork meat

Expected quality is believed to be one of the most important factors that influence consumers' intention to purchase food. The present study seeks to explore the concept of pork meat expected quality and compare it with self-stated consumer intention to purchase pork meat. The aim is attempted by means of a field research conducted in Greece, following a conjoint analytic procedure. Results show that quality expectations comply with intention to buy pork, in many aspects. However, several differences have been identified. More specifically, country of origin and marbling appear to be more important for respondents' purchase decisions than they are for their quality evaluations, while the opposite appears to be true for price. Finally, socio-demographic factors such as gender, level of education, place of purchase and consumption habits seem to influence perceptions.     

Low-frequency dielectric spectrum to determine pork meat quality

The use of dielectric spectra to determine meat quality classes (PSE, DFD, RFN) in porcine muscle during postmortem period was evaluated. The changes in dielectric properties during meat ageing were also analyzed for each meat quality class. For these purposes, dielectric spectra were measured from 100 Hz to 0.4 MHz in parallel and in perpendicular to muscle fiber directions. Significant differences (p < 0.05) in dielectric constant and loss factor among classes were observed at 24 and 48 h post-mortem. Thus, the use of dielectric properties to detect low meat qualities is more reliable at 24 h after slaughtering. Moreover, two indexes for evaluating meat ageing were developed from dielectric properties with good results. This research is the first step for developing a sensor based on electromagnetic waves at radio frequencies for controlling pork meat quality. The results are promising and some definite frequencies are demonstrated to be useful for these purposes.Industrial RelevanceThe results of this research article are demonstrated to be useful for discriminating low meat qualities (PSE and DFD meats). Thus, the industrial relevance is clear in this case because the detection of low meat qualities is identified as one of the most important challenges of meat industry nowadays. On the other hand, basing on the results of the present paper it is possible to develop a prototype for industrial applications. Moreover, two possible Indexes are developed in the present paper for determining meat freshness which also can be considered important from an industrial point of view. All this determinations were made by using dielectric spectroscopy which can be considered an emerging technology. For all these reasons we are sending to this journal “Innovative Food Science and Emerging Technologies” our results.