Postmortem pH Research Articles

Effect of Physico-chemical Characteristics of Raw Muscles from Three Iberian × Duroc Genotypes on Dry-cured Meat Products Quality

The effect of raw material characteristics (longissimus dorsi and biceps femoris) on dry-cured loin and ham quality from three different Iberian · Duroc genotypes was studied: GEN1: ♂ Iberian · ♀ Duroc1, GEN2: ♂ Duroc1 · ♀ Iberian; GEN3: ♂ Duroc2 · ♀ Iberian. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The line Duroc1 (DU1) was selected for the manufacture of dry-cured meat products, whereas the line Duroc2 (DU2) was selected for meat production with low carcass fat. Raw material and dry-cured meat products did not differ between reciprocal crosses (GEN1 vs. GEN2). However, the genotype of the Duroc sire line affected the quality of meat and dry-cured meat products. GEN1 and GEN2 had higher adipogenic nature and higher postmortem pH than GEN3, and as a result, these dry-cured meat products had better instrumental and sensory quality than those from GEN3. By contrast, meat from GEN3 had lower pH, fat content, and oxidative stability which decreased the quality of dry-cured meat products. Therefore, there was a close connection between raw material and dry-cured meat products quality as it was affected by characteristics related to the genotype such as the adipogenic character and meat quality traits associated with pH.

Effects of temperature conditioning on postmortem changes in physico-chemical properties in Korean native cattle (Hanwoo)

The objective of this study was to examine the changes in physico-chemical properties that occur after adjusting postmortem chilling temperatures in Hanwoo beef. The right sides of beef carcasses were chilled for 4 h at 2 °C, 4 h at 12 °C and 16 h at 2 °C. The left sides were used as controls, chilled for 24 h at 2 °C. It took 8 h for the control carcasses to cool down to <10 °C and 10 h 20 min for the treatment. Adjusting the chilling temperature could be effective in lowering the postmortem pH and glycogen content. Treatment muscles at least 8 h postmortem had longer sarcomeres than the control ( P < 0.05). The shear force in treatment carcasses at day 1 was similar to that of the control at day 6. Alternate chilling temperature had no detrimental effect on drip, cooking, total loss or color. Total numbers of aerobic plate counts were not significantly different between the control and treatment.

Mechanisms controlling pork quality development: The biochemistry controlling postmortem energy metabolism

Pale, soft and exudative (PSE) pork represents considerable economic losses for the industry due to its limited functionality and undesirable appearance. During the past several decades, exhaustive research covering various aspects of the food chain has established genotyping procedures, recommended handling practices, and quality indicators in order to reduce the incidence of inferior pork quality. Despite these efforts, there is still a relatively high occurrence of PSE pork. Development of pork quality attributes is largely governed by the rate and extent of postmortem pH decline. The combination of high temperature at low pH or abnormally low ultimate pH causes denaturation of sarcoplasmic and myofibrillar proteins, resulting in paler color and reduced water holding capacity. The pH decline is closely related to muscle energy availability and demand at or around slaughter. The postmortem degradation of glycogen through glycogenolysis and glycolysis provides ATP to help meet energy demand and decreases pH by generating lactate and H+. Therefore, the flux of metabolites through glycolysis, the involvement of energy signaling pathways that modulate glycolytic activity, and the inherent metabolism of different fiber types are critical factors influencing pH decline and pork quality. Further, recent work implicates adenosine monophosphate-activated protein kinase (AMPK) as a major energy sensor for the cell, and thus may be involved in the control of postmortem metabolism. The intent of this paper is to review the biochemistry controlling postmortem energy metabolism in pig muscle and explore new information generated using genetic mutations in order to define the fundamental mechanisms controlling the transformation of muscle to meat.

The crossbreeding of different Duroc lines with the Iberian pig affects colour and oxidative stability of meat during storage

Colour and oxidative stability of Longissimus dorsi (LD) and Biceps femoris (BF) muscles from 3 different Iberian × Duroc genotypes (GEN1: ♂ Iberian × ♀ Duroc1, GEN2: ♂ Duroc1 × ♀ Iberian; GEN3: ♂ Duroc2 × ♀ Iberian) were analysed during 10 days of refrigerated storage. GEN1 and GEN2 are reciprocal crosses, while the difference between GEN2 and GEN3 is the Duroc sire line. The genotype Duroc1 was selected for the manufacture of dry-cured-meat products while the genotype Duroc2 was selected for meat production. BF showed more intense colour and oxidative changes during storage than LD, which is in accordance with their different metabolic pattern, since BF is an intermediate oxidative muscle whereas LD is a glycolytic one. Important differences were found between crosses due to the genotype of the Duroc sire line; however, reciprocal crosses (GEN1 and GEN2) showed a similar pattern. The lowest post-mortem pH of GEN3 could be a deciding factor of the oxidative and colour stability during storage as GEN3 had higher drip and cook loss as well as higher susceptibility to iron-ascorbate-induced oxidation. In addition, chops from GEN3 were paler (lower L ∗) and showed a higher discolouration (higher decrease of a ∗) besides higher lipid (TBA-RS) and protein oxidation (carbonyl content) after the storage.

Rate and extent of pH decline affect proteolysis of cytoskeletal proteins and water-holding capacity in pork

The objective of this study was to determine the extent to which early postmortem (PM) pH decline influences proteolysis of the intermediate filament protein desmin, the costameric proteins vinculin and talin and autolysis of μ-calpain in the longissimus muscle (LM) of pigs from two genetic lines. Based on the LM 3 h pH (H = 3 h pH of LM > 6.0; L = 3 h pH of LM pH < 5.7) PM, 10 carcasses per line and pH group were selected. The average 3 h pH within pH group was 6.23 (H) and 5.44 (L). The LM samples were collected 24, 48, 72, and 120 h PM and percent drip loss was measured after 1, 2, and 4 d of storage. Samples collected at 24, 48, 72, and 120 h PM were used to monitor desmin, vinculin, and talin degradation and samples collected at 24 h PM were used to determine the extent of μ-calpain autolysis by immunoblotting. Higher ( P < 0.01) pH values at 45 min, 6 h, and 24 h PM and lower ( P < 0.01) drip losses after 1, 2, and 4 d of storage were recorded in the H-compared to the L-group. Abundance of the 76 kDa μ-calpain autolysis product was greater ( P < 0.01), proteolysis of talin at all measured time points and proteolysis of desmin after 24 and 48 h PM was greater ( P ⩽ 0.03) in the H-group than in the L-group. The current findings indicate activation rate of μ-calpain may be associated with proteolysis of desmin and talin and could play a role in the development of drip loss. The rate of early PM pH decline can partly explain the variation of desmin and talin degradation by affecting the activation of μ-calpain.

Factors Affecting Fat Distribution in Pork Carcasses

ABSTRACT Fat distribution and pork quality were evaluated in carcasses of 2 genetic populations with different rates of lean growth. At 60 kg BW, 48 pigs of each genetic population were fed diets without beef tallow (NBT) or with 5% added beef tallow (BT). Pigs were harvested at 105, 120, and 135 kg BW. The 4 primal cuts were dissected into lean, subcutaneous fat, and intermuscular fat, which were analyzed for percent lipid. Carcasses of the high-lean genetic population contained less (P 0.05) total fat or total fat-free lean. Pigs fed BT had heavier (P 0.05) 24-h postmortem pH, Hunter color values, longissimus muscle (LM) area, drip loss, or loin color, firmness, and marbling scores. Percent LM intramuscular fat was not affected by BT in the high-lean pigs (BT: 1.89 vs. NBT: 1.85%), but was increased (P

Difference in tenderness and pH decline between water buffalo meat and beef during postmortem aging

The objective of this research was to determine the difference in tenderness and some characteristics of water buffalo meat and beef during postmortem aging. Five female crossbred water-buffalo (Philippine Carabao × Bulgarian Murrah) and five female crossbred cattle (Brahman × Philippine Native), were finished on the same diet for 6 months and slaughtered at 30 months of age. The muscle pH was measured at 40 min, 3 h, 7 h, 24 h, and 48 h postmortem. Longissimus thoracis (LT) and semimembranosus (SM) muscles were excised at 2 d postmortem, and shear force was measured at 2, 4, 7, and 14 d postmortem. Glycogen and lactate concentrations were determined from 0, 2, and 4 d LT samples, and myosin heavy chain type of buffalo and cattle LT was determined by ELISA methods. Myofibrillar protein degradation was also observed by SDS–PAGE and Western blotting of fast-type troponin T. Results showed that the buffalo meat had significantly lower shear force values compared to beef for LT and SM muscles, which was supported by a difference in troponin T degradation. Postmortem pH decline of buffalo meat was significantly slower than that of beef, which was confirmed by lactic acid concentrations, but was not explained by glycogen content. In addition, there was no significant difference in the ratio of slow to fast type muscle fibers in buffalo and cattle, indicating that myosin heavy chain type was not responsible for the difference in pH decline and tenderness between the buffalo meat and beef. This study demonstrated that the tenderness of water buffalo meat was superior to that of Brahman beef, which may have been due to the difference in pH decline and the subsequent effect on muscle protease activity.

Carcass composition and meat quality of three different Iberian × Duroc genotype pigs

Carcass composition and meat quality of Longissimus dorsi (LD) and Biceps femoris (BF) muscles from three different Iberian × Duroc genotype pigs were studied: GEN1: ♂ Iberian × ♀ Duroc1; GEN2: ♂ Duroc1 × ♀ Iberian; GEN3: ♂ Duroc2 × ♀ Iberian. Duroc1 (DU1) were selected for the manufacture of dry-cured meat products while Duroc2 (DU2) were pigs selected for meat production, with high percentages of meat cuts and low carcass fat. Genotype had a significant effect on the differences found while sex had not. GEN2 showed the highest weights at days 180 and 238 of weaning and the highest slaughter weights (day 316) followed by GEN3, while the lowest weights were found in GEN1. GEN3 had well conformed carcasses in comparison with GEN1 and GEN2, since GEN3 showed the highest percentages of ham and loin and the highest weight of loin as well as the lowest back and ham fat thickness. However, the use of DU2 pigs in the cross with Iberian had negative effects on meat quality, as GEN3 gave the worst meat quality in both muscles, postmortem pH, cook and drip loss, and colour and the lowest percentages of intramuscular fat (IMF). In subcutaneous fat (SCF), GEN3 had higher percentages of polyunsaturated fatty acids (PUFA) than GEN2, while GEN2 had higher saturated fatty acids (SFA) levels. In LD, IMF from GEN3 showed the highest percentage of MUFA and PUFA; while the fatty acid profile of GEN2 was more saturated. BF muscle showed similar trends, but not significantly so. On the other hand, few differences were found between reciprocal crosses (GEN1 vs. GEN2). GEN2 showed higher IMF in LD than GEN1, agreeing with their carcass weight. As a result, GEN1 had a fatty acid profile of IMF in the LD that was more unsaturated.

Impact of RN genotype and ageing time on colour characteristics of the pork muscles longissimus dorsi and semimembranosus

The effect of RN genotype on pH decline, ultimate pH, pigment content, blooming and colour stability during 6 days of display at 5 °C was studied in two pig muscles, M. longissimus dorsi (LD) and M. semimembranosus (SM), and furthermore the effect of anaerobic storage time (2 days vs. 9 days of ageing) on the same parameters was examined. The postmortem pH decline was faster and the ultimate pH lower in LD and SM of the RN − genotype compared with corresponding muscles from the rn + genotype. Pork of the RN − genotype was initially lighter and more red and yellow than pork of the rn + genotype due to a higher degree of blooming, which might be explained by the faster pH decline and/or lower ultimate pH. The level of oxymyoglobin (MbO 2) was decisive for the redness of both muscles during display in air despite a higher presence of metmyoglobin (MetMb). Pork of the RN − genotype was thus redder than that of the rn + genotype throughout display in air despite higher oxidation to MetMb. Ageing for 9 days in chill improved the blooming potential in pork of both genotypes compared with 2 days of ageing, resulting in superior meat colour. However, only in pork from the RN − genotype, the colour was not negatively affected by ageing time upon display in air.

Slaughter stress, postmortem muscle pH and rigor development in farmed Atlantic cod (Gadus morhua L.)

Slaughter stress, postmortem muscle pH and rigor development in farmed Atlantic cod (<i>Gadus morhua</i> L.)

Creatine Monohydrate and Glucose Supplementation to Slow- and Fast-Growing Chickens Changes the Postmortem pH in Pectoralis Major

The energy status of the chicken at slaughter has a large impact on the development of pH postmortem and thus on color and water-holding capacity (WHC). Supplementation of creatine monohydrate and glucose (CMH+GLU) may increase the creatine content in the muscles before slaughter, thereby delaying the formation of lactic acid and postponing the pH decline. The objective of this study was to examine the impact of supplementing CMH+GLU in the drinking water within the last 48 h before slaughter on the pH decline, meat color, and WHC in the pectoralis major from 2 strains of Ross chickens. Forty Ross 308 (fast-growing) female chickens and 40 Ross 1972 (slow-growing) female chickens had free access to drinking water either supplemented with CMH (15 g/ L) and glucose (50 g/L) within the last 48 h before slaughter or without supplementation. All chickens were slaughtered at 42 or 43 d of age irrespective of weight. Temperature and pH were measured at 1 and 30 min and at 1, 3, 8, and 24 h postmortem. Also, WHC measured as drip loss and color were determined postmortem. The CMH+GLU supplementation decreased pH (P < 0.05) at all time points between 1 min and 8 h postmortem in both strains, whereas at 24 h postmortem only pH in Ross 308 chickens were decreased significantly upon supplementation. Lightness was significantly increased in the meat from Ross 308 but not from Ross 1972 chickens upon supplementation. This interaction was significant (P < 0.05). The redness of the meat was decreased upon supplementation (P < 0.05), although only significantly in Ross 1972. The pH was lower for Ross 1972 chickens at the early time points (P < 0.01) and also a higher drip loss (P < 0.05), lightness (P < 0.01), and redness (P < 0.001) were observed. Thus, there seems to be no beneficial effect of CMH+GLU supplementation on chicken meat quality on the basis of results from this experiment.

Influence of animal temperament and stress responsiveness on the carcass quality and beef tenderness of feedlot cattle

Three groups of steers (A, B, C) were used to study the effect of temperament (Calm, Intermediate, and Excitable) on meat quality. Temperament was based on exit velocity, pen scores, and chute scores. Temperament traits were consistent across evaluations, and values decreased ( P < 0.05) in magnitude over time. Increasing excitability was associated with higher ( P < 0.05) serum cortisol concentrations. Carcasses from cattle with calm temperaments had higher ( P < 0.05) 0.5 h postmortem pH values than those from Intermediate and Excitable cattle (0.1 and 0.2 units, respectively). Group C Excitable steers had higher ( P < 0.05) WBS values than the calmer Group C steers. This trend was observed in Group A steers, although the values were not statistically different. Correlations were highest between temperament values and tenderness after 21 d. Temperament influences tenderness, although the mechanism is not clear.

The effect of genotype and plane of nutrition on the rate of pH decline in lamb carcasses and the expression of metabolic enzymatic markers

The objective of this study was to establish the effect of sire (n = 9) estimated breeding values (EBVs) and pasture-based nutritional systems (low and high quality and availability) from birth to slaughter on the metabolic characteristics and post-mortem pH changes in muscle of ~8-month-old lambs (n = 56). Nutritional restriction resulted in a general decrease in glycolytic capacity as indicated by the enzymes phosphofructokinase and lactate dehydrogenase (LDH), suggesting greater metabolic efficiency. Alternatively, it also depressed oxidative capacity as indicated by myoglobin and isocitrate dehydrogenase, which aligns with the histological results suggesting a fast glycolytic fibre type characteristic of less mature animals. Increasing PEMD EBV resulted in a marked shift towards a metabolically more glycolytic muscle type as demonstrated by LDH, although this did not correspond strongly with an increase in the proportion of type 2B fibres based on histological assessment of myofibre type using immunostaining of myosin heavy chain isoforms. Myoglobin concentration aligned with this trend, decreasing in all muscles as PEMD EBV increased, suggesting that selection for muscling will lead to a whiter muscle appearance. Rate of pH decline was increased in the low nutrition lambs, and through selection for PEMD EBV, this response aligning with the metabolically more glycolytic muscle type.

Low birth weight is associated with enlarged muscle fiber area and impaired meat tenderness of the longissimus muscle in pigs1,2

The objective of this study was to determine the relationships between birth-weight-associated modifications in histological or chemical muscle characteristics and meat quality traits in pigs. At 68 d of age, Pietrain x (Large White x Landrace) female littermates were allocated into 2 groups on the basis of low birth weight (LW = 1.05 +/- 0.04 kg; n = 15) or high birth weight (HW = 1.89 +/- 0.02 kg; n = 15). Pigs were reared in individual pens with free access to a standard diet up to slaughter at approximately 112 kg of BW. During the growing-finishing period, LW and HW pigs had a similar daily feed consumption, whereas G:F was lower (P = 0.009) for LW pigs than for HW littermates. At final BW, LW pigs were 12 d older (P < 0.001) than HW littermates. Estimated lean meat content, relative proportions of loin and ham in the carcass, and weights of LM and semitendinosus muscle (SM) were decreased (P < 0.05) in LW pigs compared with HW pigs. Conversely, the LW pigs exhibited a fatter carcass, greater activity levels of fatty acid synthase and malic enzyme in backfat (n = 15 per group), and enlarged subcutaneous adipocytes (n = 8 per group) compared with the HW pigs. Similarly, lipid content was increased by 25% (P = 0.009), and mean adipocyte diameter was 12% greater (P = 0.008) in the SM from LW pigs compared with that from HW pigs, whereas lipid content did not vary in the LM of either group. Mean myofiber cross-sectional areas were 14% greater in the LM (P = 0.045) and the SM (P = 0.062) of LW pigs than of HW pigs. Conversely, the total number of myofibers was less (P = 0.003) in the SM of LW vs. HW pigs. There were no differences between groups for glycolytic potential at slaughter and rate and extent of postmortem pH decline in both muscles, as well as for LM drip losses. A trained sensory test panel judged the roast loin meat to be less tender (P = 0.002) in LW pigs relative to HW pigs. Scores for juiciness, flavor, flouriness, and fibrousness of meat did not differ between groups. Overall, negative but somewhat low correlation coefficients were found between LM tenderness score and ultimate pH (r = -0.36; P = 0.06) and between LM tenderness and mean cross-sectional area of myofibers (r = -0.34; P = 0.07). This study demonstrates a lower tenderness of meat from pigs that had a LW, partly as a result of their enlarged myofibers at market weight.

Properties of Tilapia Carboxy- and Oxyhemoglobin at Postmortem pH

Hemoglobin plays an important role in the color and oxidative stability of seafoods. A recent practice in the seafood industry is to stabilize muscle color by the application of gases containing carbon monoxide. The goal of this study was to examine and compare the properties of tilapia hemoglobin complexed to either O(2) (Oxy-Hb) or CO (CO-Hb) at pH 6.5, which reflects the tilapia muscle postmortem pH. CO-Hb was significantly (p < 0.01) more stable against autoxidation compared to Oxy-Hb when kept at 4 and -30 degrees C for 23 days. Almost no loss of CO was detected for both temperatures according to the UV-vis spectra of Hb. This stabilization was also believed to play a role in increased protein structure stabilization (p < 0.001) since less protein aggregation was seen for CO-Hb. The higher protein stabilization for Hb was linked to the heme group, which was maintained in its reduced state longer for CO-Hb vs Oxy-Hb and was likely less exposed to solvent. CO-Hb had significantly (p < 0.01) less peroxidase activity than Oxy-Hb and thus reactivity with H(2)O(2). The pro-oxidative activity of CO-Hb was significantly (p < 0.01) reduced in a linoleic acid micelle system compared to that of Oxy-Hb, while smaller differences in activity were seen in a washed cod and tilapia muscle model system.

Effect of Ultimate pH on the Physicochemical and Biochemical Characteristics of Turkey Breast Muscle Showing Normal Rate of Postmortem pH Fall

This experiment aimed to study the effect of ultimate pH (pHu) on the biochemical and physicochemical characteristics of turkey breast muscle with normal rate of postmortem pH fall. Five hundred turkey toms (12 wk old, 10 kg live weight) were randomly chosen from a commercial flock. At 24 h postmortem, 64 birds were randomly selected within the subgroup showing pH higher than 6.0 at 20 min postmortem and pHu lower than 6.1. These pH levels were used to exclude pale, soft, and exudative (PSE) meat and dark, firm, and dry (DFD) meat, respectively. The pHu was significantly correlated with luminance (L*; r = -0.37) and yellowness (b*; r = -0.36) at 24 h postmortem, drip losses (r = -0.56 to -0.62), thawing loss (r = -0.47), 80% compression (r = -0.29), yield of curing and cooking (r = 0.37), glycolytic potential at slaughter (r = -0.44) and lactate at 24 h postmortem (r = -0.47). Significant correlations were found between drip losses and compression test on cooked meat (r = 0.27 to 0.34). Cooking loss was correlated with WB shear force (r = 0.32). These results show that when PSE defects are excluded, the intensities of the correlations between pHu and meat quality traits are lower than those usually reported. The present data also indicate that the level of glycogen at time of slaughter poorly explains the variability in pHu. Thus, further research is needed to identify the mechanisms explaining pHu variation in poultry muscle.

Water-Holding Capacity in Chicken Breast Muscle is Enhanced by Pyruvate and Reduced by Creatine Supplements

In commercial production, chickens are subjected to feed withdrawal prior to slaughter and exposed to stress during transport and handling of the animals at the slaughterhouse; this causes plasma glucose and glycogen stores in liver and muscle to decrease, which has a negative impact on meat quality. The aim of the present study was to investigate how supplementation of the energy complements creatine and pyruvate during the fasting period would affect postmortem pH decrease, water-holding capacity, and color of the meat. Female Ross 208 broilers were supplemented with glucose combined with either pyruvate or creatine via the drinking water for 18 or 42 h prior to slaughter, i.e., before and throughout the fasting period. Chickens were slaughtered at 42 or 43 d of age. Temperature and pH were measured at 1, 10, 30, and 45 min and 1, 2, 4, 8, and 12 h postmortem. The results showed that the pyruvate and glucose supplementation increased the pH at 45 min postmortem by 0.25 units and decreased drip loss of musculus pectoralis major (PM) by 50 to 65% in chickens supplemented for 42 h. The creatine and glucose supplementation reduced pH at 3 and 4 h postmortem by 0.32 to 0.42 units, increased the lightness (L*) by 2.3 to 5.6 units, and increased drip loss by 51 to 137% in the PM of chickens supplemented for 18 and 42 h. Pyruvate and glucose supplementation thus appear beneficial but whether this is concomitant with an overall improvement in meat quality remains to be determined.

Influence of harvest processes on pork loin and ham quality1

The purpose of this study was to determine the specific effects of extending the interval between dwell time and the duration of scalding on pork quality attributes. Sixty-four Duroc x Yorkshire pigs were randomly assigned to a 2 x 2 factorial treatment arrangement. Treatments included extending the dwell duration from 5 to 10 min and extending the scald duration from 5 to 8 min. All carcasses entered the cooler 50 min after exsanguination. At exsanguination, blood was collected for three 1-min intervals and then for a final 2-min period. Temperature and pH of the LM and semimembranosus muscle (SM) were measured at 45 min, and at 2, 4, 6, and 24 h postmortem (PM). Hunter L*, a*, and b* values were determined on the LM, SM, and biceps femoris (BF). Purge loss was measured on the SM, BF, and the sirloin end of the loin. Drip loss was measured in duplicate from LM chops after 1 and 5 d of storage. Warner-Bratzler shear force (WBS) measurements were determined on LM chops aged 1, 3, 5, and 7 d PM. Over 99% of the collected blood was obtained during the first 3 min after sticking. Carcasses scalded for 8 min had greater (P < 0.05) semi-membranosus 2 h temperature (28.8 degrees C) than carcasses scalded 5 min (27.3 degrees C). An 8-min scald process resulted in longissimus dorsi chops with lower hue angle and greater WBS values than the 5-min scald process. Increasing dwell time from 5 to 10 min resulted in biceps femoris chops with greater hue angle and loin chops with greater WBS values at 3 d PM. Harvest processes did not significantly affect subjective quality scores, Hunter L* values, purge or drip loss. Lengthening the duration of dwell and scalding may result in a more rapid PM pH decline. Reducing the duration of scalding may lead to increased time for manual removal of hair. Because of differences in facilities, it is recommended that individual facilities monitor dwell and scald durations to determine how to best minimize time of entry into the cooler.

비육돈 사료의 영양소 수준이 돈육 품질에 미치는 영향

본 시험은 비육돈 사료의 변화가 돈육의 일반성분, 이화학적 특성, 육색, 아미노산 및 지방산 조성에 미치는 영향을 조사하기 위해 실시하였다. 60<TEX>${\pm}$</TEX>3kg의 삼원교잡종 240두를 공시하여 비육돈 사료 변화의 영양소 수준에 따라 대조구는 저영양소 사료 ME 2,960kcal/kg, CP 12.25%, Lysine 0.41%, Ca 0.70, T1은 중영양소 사료 ME 3,220kcal/kg, CP 15.50%, Lysine 0.87%, Ca 0.90 및 T2는 고영양소 사료 ME 3,350kcal/kg, CP 17.50%, Lysine 1.08%, Ca 0.90%로 배합한 사료를 66일간 급여하였다. 단백질, 지방 및 수분 함량은 대조구와 처리구간에 유사하였으며, 조회분 함량은 T1 처리구가 대조구와 T2 처리구에 비해 유의적으로 높았다(p〈0.05). 최종 pH<TEX>$_{u}$</TEX>는 T2 처리구가 대조구와 T1 처리구에 비해 유의적으로 높았고, 반면 가열감량은 낮게 나타났다(p〈0.05). 필수아미노산인 Threonine, Isoleucine 및 Histidine는 T2 처리구가 대조구에 비해 높은 반면 비필수아미노산인 Proline과 Glycine는 유의적으로 낮았다(p〈0.05). 대조구가 T1 처리구와 T2 처리구에 비해 포화지방산 및 단일불포화지방산 함량은 높은 경향을 보였고 특히, Oleic acid(18:1) 함량은 유의적으로 높았다(p〈0.05). 다가불포화지방산인 linoleic acid(C18:2)와 arachidonic acid(C20:4) 함량은 대조구에 비해 T1 및 T2 처리구가 유의적으로 높았다(p〈0.05). 이상에서 비육돈 사료 변화의 영양소 수준이 높은 T2 사료를 급여했을 때, 이화학적 특성에서 pH<TEX>$_{u}$</TEX>가 높고 가열 감량이 낮아 돈육품질이 향상되었으며 일반성분, 아미노산 및 지방산 조성에서도 대조구와 차이를 보였다. In a trial involving 240pigs, the proximate composition, physico-chemical properites, color, amino acid composition and fatty acid composition of loin muscle were investigated in feeding various finished pig feeds. The treatments included feeding control) the low-nutrient density diet(2,960cal/kg ME, 12.25% CP, 0.41% lysine and 0.70% Ca), T1) the medium-nutrient density diet(3,220cal/kg ME, 15.50% CP, 0.87% lysine and 0.90% Ca) and T2) the hight-nutrient density diet(3,350cal/kg ME, 17.50% CP, 1.05% lysine and 0.90% Ca). The crude ash contents of T1 were significantly(p〈0.05) higher than those of control and T2. The pH<TEX>$_{u}$</TEX> of T2 were significantly higher than those of control and T1, but cooking loss were significantly(p〈0.05) lower than those of control. In compositions amino acid, aspartic acid, threonine, iso-leucine and histidine of T2 were higher than those of control, but proline and glycine were significantly(p〈0.05) lower then those of control. The oleic acid(18:1) contents of control were significantly higher than those of T1 and T2, but the contents of linoleic acid(C18:2) and arachidonic(C20:4) acid were significantly(p〈0.05) lower. Inconclusion, the results of the experiments suggest that the high-nutrient density diet for pigs tended to improve the postmortem pH<TEX>$_{u}$</TEX> and cooking loss.

Effects of feeding different levels of conjugated linoleic acid and total oil to pigs on subsequent pork quality and palatability

The objective of the present study was to compare pork quality, composition and palatability of pigs fed different levels of conjugated linoleic acid (CLA) and total oil (TO). A 3 × 2 factorial design was used feeding three levels of CLA (0, 0.25, and 0. 5%) and two levels of TO (2 and 5% made up with canola oil). Thirty-six pigs were allotted per diet and diets were fed from 35 to 115 kg liveweight. TO had no effect on longissimus thoracis (LT) moisture or intramuscular fat contents, but feeding CLA decreased LT moisture (P = 0.04) and increased LT intramuscular fat (P = 0.04). CLA and TO had no effect on LT subjective color, structure or marbling scores. Post-mortem LT temperature was also unaffected by feeding CLA or TO. Pigs fed 0.5% CLA had a marginally higher muscle pH (P = 0.01), a tendency toward lower post-mortem lactate levels (P = 0.06) and had higher glycogen concentrations (P = 0.03) at 30 min post mortem. Feeding CLA may thus offer limited protection against rapid post-mortem pH decline. Adding CLA to the diet increased subcutaneous fat hardness (P = 0.01), which was related to increased saturated (P = 0.01) and reduced monounsaturated fatty acid levels (P = 0.01). Increasing TO had an opposite effect resulting in softer fat with lower saturated and higher mono- and polyunsaturated fatty acid levels (P = 0.01). Supplementing diets with CLA in combination with canola oil did not have any detrimental effect on pork quality, composition or palatability. Feeding CLA does, however, have the potential to improve pork quality by increasing intramuscular fat levels, reducing post-mortem glycogen utilization rates and increasing subcutaneous fat hardness. Key words: Conjugated linoleic acid, canola oil, pork quality, palatability, marbling, fat composition