Structural weakening of intramuscular connective tissue during postmortem aging of pork

We studied structural changes in the endomysium and perimysium during postmortem aging of pork using the cell‐maceration/scanning electron microscope method. Immediately post mortem, endomysia sheaths that house individual muscle fibers displayed a honeycomb‐like structure. The sheaths of the endomysium consisted of tightly arranged collagen fibrils in a random network. The perimysium comprised several layers of wavy sheets made up of tightly bundled collagen fibers. While the structure of the intramuscular connective tissues remained almost unchanged up to five days post mortem, the endomysium had resolved into individual collagen fibrils, and the thick sheets of the perimysium had separated into collagen fibers and fibrils at 8 days post mortem. These results provide direct evidence for structural weakening of the endomysium and perimysium during postmortem aging of pork. The shear‐force value of raw pork decreased rapidly within six days post mortem and then decreased slowly until 14 days post mortem. Since the rapid increase in tenderness is mainly due to structural weakening of myofibrils, we conclude that the disintegration of the endomysium and perimysium contributes to tenderization of pork during extended postmortem aging.     

影响猪肉品质的主基因及其研究进展

影响猪肉品质的因素很多,但遗传基础是改善猪肉品质的关键。本文将对影响猪肉品质的两种主基因:氟烷基因(Hal)和酸肉基因(RN)的研究现状作一综述。     

Influence of harvest processes on pork loin and ham quality

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.     

Effect of a low‐voltage electrical stimulation on yak meat tenderness during postmortem aging

This study evaluates the effect of a low‐voltage electrical stimulation (ES) on the tenderness of yak longissimus muscle (LM). Samples from 16 yak bulls were divided into four treatment groups: normal chilling (NC), ES and chilling (ES & C) for 72 s (ES &C 72 s), ES & C for 90 s (ES & C 90 s), and ES & C for 108 s (ES & C 108 s). The temperature, the pH, the glycogen content, the Warner‐Bratzler shear force (WBSF), the myofibril fragmentation index (MFI), and the muscle ultrastructure were determined during the course of postmortem aging. ES caused a rapid decrease in the pH to form a high‐temperature and low‐pH environment. The glycogen content gradually decreased with aging. The WBSF value of the ES & C groups was significantly lower than for the NC group (p < .05). The MFI values of ES & C groups after 24 hr postmortem aging were significantly higher than for the NC group. We concluded that ES improved yak meat tenderness during postmortem aging and that the different duration time by ES indicated different effects, and its affect was remarkable in the ES & C 90 s.     

植物提取物对育肥猪生长性能、胴体性状、猪肉品质及抗氧化能力的影响

本试验旨在研究植物提取物对育肥猪生长性能、胴体性状、肉品质及猪肉抗氧化能力的影响。选用20头体重相近[(83.75±5.83 kg)]的PIC猪,随机分为对照组(基础日粮)和试验组(基础日粮中额外添加0.04%植物提取物),每个处理5个重复,每个重复2头猪。结果表明,两组间育肥猪采食量、日增重、料肉比和胴体性状差异不显著(P>0.05)。与对照组相比,试验组肉色a*45min值显著提高(P<0.05),L*96 h值极显著降低(P<0.01);4℃下储存0、3 d和7 d猪肉,试验组肉样中丙二醛(MDA)的含量显著降低,超氧化物歧化酶(SOD)活性显著提高(P<0.05)。因此,饲粮中添加植物提取物有利于储存中猪肉品质的改善。     

Comparison of histochemical characteristics in various pork groups categorized by postmortem metabolic rate and pork quality

The purpose of the present study was to investigate the variations in histochemical characteristics of muscle samples segregated according to metabolic rates (MR) and pork quality attributes. A total of 231 crossbred Duroc x (Yorkshire x Landrace) pigs was evaluated. Samples of the LM were taken to evaluate histochemical characteristics, postmortem MR, and meat quality. Samples were classified into fast, normal, and slow MR groups based on muscle pH at 45 min and R-value. Drip loss and lightness (L*) were used to assign samples to 1 of 4 quality classes. Pale, soft, and exudative pork belonging in the fast group had the greatest (P < 0.05) percentage of type IIb fibers, and RSE (reddish-pink, soft, and exudative) pork belonging in the fast group had a similar tendency. Additionally, RFN (reddish-pink, firm, and nonexudative) pork belonging in the normal group showed a lower (P < 0.05) percentage of type IIb fibers than PSE or RSE, regardless of MR, and DFD pork had the lowest (P < 0.05) percentage of type IIb fibers. In general, the fast-glycolyzing PSE pork with the lowest pH at both 45 min and 24 h had greater percentages of type IIb fibers than the fast-glycolyzing RFN pork. There were more fiber-type composition differences between quality classes in pork undergoing a fast rate of metabolism compared with pork undergoing a normal rate of metabolism. It can be concluded that muscle histochemical characteristics are associated with early postmortem MR, the extent of glycolysis, and, thereby, pork quality; however, these effects are limited to the pigs exhibiting a fast glycolytic rate.     

Slaughterline records of various postmortem pathological lesions and their influence on carcass and meat quality in slaughtered pigs

The aim of this study was to identify the prevalence of pathological lesions in pigs from small‐scale farms and to determine associations between pathological lesions and hematological parameters, and carcass and meat quality in slaughtered pigs. The study was conducted on 625 pigs (~115 kg) originating from 20 small‐scale farms. Any signs of pneumonia, pleurisy, pericarditis, and liver milk spots were recorded as present or absent. Complete blood count was investigated. The following carcass quality parameters were measured: live, hot and cold carcass weights, cooling loss, dressing percentage, backfat thickness, and meatiness. Meat pH and temperature were measured 45 min postmortem. Of the 625 examined pigs, 41.8% had pneumonia, 23.5% pleurisy, 2.7% pericarditis, and 29.9% liver milk spots. The presence of pathological lesions in slaughtered pigs adversely affected hematological parameters, reduced live, hot and cold carcass weights, and meatiness and had deleterious effects on meat quality (higher pH_45min and higher prevalence of dark, firm and dry meat). In conclusion, this study showed a high prevalence of pathological lesions in slaughtered pigs, indicating serious health problems in smallholder pig production systems. The presence of single and, especially, multiple pathological lesions in slaughtered pigs negatively affected hematological parameters, and carcass and meat quality.     

Effects of fasting and transportation on pork quality development and extent of postmortem metabolism

One hundred seventy-seven pigs were used to determine the interaction effects of fasting and length of transport prior to harvest on pork muscle quality. The study design was a 2 x 2 x 3 factorial, which involved two genetic sources, fasting (F) or no fasting (N) of pigs 48-h prior to harvest, and three transport times (0.5, 2.5, or 8.0 h) on a semitrailer to the packing plant. Genetic source was a significant source of variation (P < 0.05) for most composition and muscle quality variables. Fasting reduced hot carcass weight 3.6% (P < 0.05), but length of transport did not affect hot carcass weight (P > 0.05). There were no differences (P > 0.05) in percent lean among fasting and transport treatments. Fasted pigs had higher longissimus dorsi (LD) ultimate pH (pHu), darker lean color, higher marbling score and lower 7-d purge loss, 24-h drip loss, and cooking loss (P < 0.05) than nonfasted pigs. Meat from pigs that were transported 8.0 h had lower glycolytic potential (GP), higher LD and semimembranosus (SM) pHu, darker lean color, and lower L*, 7-d purge loss, 24-h drip loss, cooking loss, and shear force values than meat from pigs transported 0.5 h (P < 0.05). Meat from pigs transported 2.5 h had higher LD and SM pHu and lower L*, 7-d purge loss, 24-h drip loss, and cooking loss than meat from pigs transported 0.5 h (P < 0.05). Meat from pigs transported 8.0 h had higher LD pHu and color scores and lower L* and cooking loss than meat from pigs transported 2.5 h (P < 0.05). The fasting x transport interaction was significant for SM pHu, L*, color score, and drip loss. Fasting improved SM pHu, L*, color score, and drip loss for pigs that were transported 0.5 h (P < 0.05), but when pigs were transported for 2.5 h or 8.0 h, fasting had little or no effect on these muscle quality traits. Fasting lowered GP and increased LD pHu for pigs from the genetic source with the higher initial pork quality (P < 0.05), while fasting had no effect on pork quality for pigs from the genetic source with the lower initial pork quality (P > 0.05). Longer transport times resulted in lower GP and higher LD pHu regardless of genetic source. Fasting and length of transport each had positive effects on pork quality, but length of transport effects was greater in magnitude. When pigs were transported for 0.5 h, fasting for 48 h prior to harvest improved pork quality, but when pigs were transported 2.5 or 8.0 h, fasting had little effect on pork quality.     

Effect of deep-freeze storage time and thawing method on intramuscular lipids oxidation and sensory quality of pork loin

In the present study, microwave thawing was compared with conventional thawing in atmospheric air. It was found that the quality of intramuscular lipids, reflected in the acid value, deteriorated during six-month deep-freeze storage, irrespective of the thawing method. The sensory quality of m. longissimus dorsi was related to the thawing method and the time of deep-freeze storage. The rate of changes was faster in samples thawed in the air, compared to those thawed in a microwave oven.     

猪肉品质的评价指标及其影响因素

本文对猪肉品质的评价指标及其影响因素进行探讨。     

互助猪胴体性状和肉脂品质的测定及其相关分析

测定了２５头互助猪的胴体性能和肉脂品质，结果表明，互助猪的胴体性能远远劣于国外瘦肉型猪，但优于国内某些地方猪种，瘦肉率低是其显著特点；肉脂品质优于国外瘦肉型猪，表现在良好肉色和肌间脂肪含量，相关分析表明，互助猪的产瘦肉能力与肉脂品质呈出一定的拮抗关系，表现为胴体瘦肉率愈高，背膘愈薄，肌间脂肪含量就愈低，贮存损失率也愈大。     

Effects of postmortem calcium chloride injection on meat palatability traits of strip loin steaks from cattle supplemented with or without zilpaterol hydrochloride

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P < 0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P < 0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values < 4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P > 0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P < 0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P < 0.05) MFI values, but INJ resulted in greater (P < 0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P < 0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.     

地方品种猪肉品质及其膳食营养论述

随着社会经济的快速发展与人民生活水平的不断提高,消费者对肉制品的食品安全、风味与口感、营养与健康有了更高的要求.大量试验研究表明,我国地方猪种的肉品质相比长白猪、大约克猪、杜洛克猪、杜长大猪等国外品种品系,有着明显优势.文章对我国地方品种猪肉品质的优势特点及其膳食营养和对人体健康的影响进行综述.     

壳聚糖对天山雪鹅屠宰性能及肉品质的影响

本试验旨在研究壳聚糖对天山雪鹅屠宰性能及肉品质的影响,选用健康1日龄天山雪鹅100只,随机分为5组。对照组饲喂基础日粮,试验组分别饲喂基础日粮中添加100、200、300g/t和400g/t壳聚糖的试验组日粮,试验期42d。结果表明:日粮中添加不同水平的壳聚糖可显著降低天山雪鹅屠体脂肪含量(P0.05);但对其他屠宰性能无显著影响(P0.05);鹅肉的pH和干物质含量无显著变化(P0.05),但粗蛋白质含量有所增加,脂肪含量有所下降。     

中药提高猪肉品质应用上的研究进展

如今受集约化养殖弊端的影响,动物的活动量大量减少.相较于野猪和放养猪的肉质而言,集约化养殖的猪肉品质较差,因此寻找合适的添加剂对集约化养殖的猪肉进行改善显得尤为重要.而中药属于天然药物,具有无残留、无耐药性和低毒副作用等特点,且具有提高肉品质的作用,因此受到越来越多的学者的关注.文章主要介绍了中药的特点、功能及其对猪肉...     

The effect of inulin supply to high‐fat diet rich in saturated fatty acids on pork quality and profile of sarcoplasmic protein in meat exudate

The aim of the study was to evaluate the influence of inulin supply to high‐fat diet rich in saturated fatty acids (SFA) on pork quality and profile of sarcoplasmic protein in drip loss. At 50 days of age, twenty cross‐bred pigs (gilts) were randomly allotted to four groups: the control (C) group fed a standard diet, and three experimental (D1, D2 and D3) groups fed a high‐fat diet rich in SFA. Moreover, pigs from the groups D2 and D3 consumed an extra inulin supply (7% of daily feed intake) from 85 to 120 days of age (for 5 weeks) and from 50 to 120 days of age (for 10 weeks) respectively. The addition of inulin to the diet reduced meaty odour and flavour significantly, improved tenderness and overall sensory quality of pork and additionally influenced ultimate pH, L* colour parameter, lactate level and protein content in meat. The diets also affected the profile of sarcoplasmic proteins. Significant effects were observed for the following enzymes—PK/PGI (pyruvate kinase/phosphoglucose isomerase) and ALD (aldolase), which are related to the intensity of post‐mortem glycolysis. Presented data indicate that long‐term inulin supply to high‐fat diet has a positive effect on technological and sensory quality as well as protein profile of pork.     

Comparison of the antioxidant activities of 22 commonly used culinary herbs and spices on the lipid oxidation of pork meat

The antioxidant activities of 22 selected culinary herbs and spices (i.e. ginger, cinnamon, clove, bay, sage, rosemary, thyme, savory, oregano, sweet basil, parsley, coriander, tarragon, sansho, allspice, cumin, black and white peppercorns, nutmeg, caraway, dill and fennel) when they were added to pork homogenate were measured and expressed as a thiobarbituric acid (TBA) value. The addition of liquid extracts of all the herbs and spices significantly suppressed lipid oxidation of the pork, especially the extracts of sansho, sage and ginger, which showed the strongest inhibition of lipid oxidation.     

不同复合氨基酸-金属配合物添加剂对猪肉质量的作用效果

对饲喂复合氨基酸 金属配合物不同添加剂组合的生长育肥猪肉品质和化学成分进行分析测定 ,结果表明 ,不同复合氨基酸 金属配合物添加剂对生长育肥猪肉品质和化学成分的改善都有良好的促进作用 ,提高了猪肉的质量 ,其中以复合氨基酸 微量元素 稀土元素配合物饲料添加剂的作用更为明显。