The effects of high pressure processing on pork quality, palatability, and further processed products

The objective was to evaluate high pressure processing (HPP) on postmortem metabolism and pork quality. Six pigs were randomly selected immediately after slaughter. After splitting, one side was randomly designated for HPP of 215 MPa for 15 s with water temperature at 33 °C and the other side (non-pressure treated) served as the control. Chilled sides were fabricated into loins, boneless picnic, boneless Boston butt, and ham. Samples were cut from the loin, inside portion of the ham and cushion (M. triceps brachii). Pork quality, lipid oxidation, connective tissue solubility, protein functionality, sensory analysis, and processed characteristics of restructured hams were evaluated. HPP partially inhibits postmortem metabolism, indicated by lower muscle lactate levels and higher ultimate pH values. Cook and drip loss were both reduced in HPP treated muscles compared to controls. HPP treated sides were more tender than controls. Collagen content was not different between HPP and control groups.     

Utilization of Pork Collagen Protein in Emulsified and Whole Muscle Meat Products

ABSTRACT: Effects of pork collagen in emulsified and whole muscle products were evaluated. Eight frankfurter treatments (0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, and 3.5% pork collagen) and 4 ham treatments (0%, 1%, 2%, and 3% pork collagen) were formulated. Frankfurters and hams were evaluated for cooked yields, purge, color, texture, and sensory characteristics. Incorporation of pork collagen at 1% and above significantly ( P < 0.05) increased cooked and chilled yields in frankfurters but did not have any effect in hams. Purge was significantly ( P < 0.05) reduced in both frankfurters and hams after 4 wk of storage. Sensory difference testing showed no significant difference up to 2% usage level of pork collagen in both frankfurters and hams ( P > 0.05).     

Utilization of response surface modeling to evaluate the effects of non-meat adjuncts and combinations of PSE and RFN pork on water holding capacity and cooked color in the production of boneless cured pork

Boneless cured pork was produced from combinations of pale, soft, and exudative (PSE) and red, firm, and non-exudative (RFN) semimembranosus muscle. Response Surface Methodology was utilized to determine the effects of soy protein concentrate (SPC), sodium caseinate (SC), and modified food starch (MFS) on the water holding capacity and cooked color in a chunked and formed product. Fifteen ingredient combinations were replicated three times for each PSE and RFN combination giving 75 treatments per replication. Utilization of SPC decreased (P<0.01) cooking loss and redness while increasing (P<0.01) yellowness. MFS decreased (P<0.01) expressible moisture, and both MFS and SC increased (P<0.05) cooked redness while decreasing (P<0.01) cooked lightness. Product formulations using these adjuncts demonstrate potential to improve the water-holding capacity and cooked color in PSE as well as RFN pork. This research also demonstrated that diluting RFN pork with no more than 25% PSE pork permits the formation of a high quality boneless deli ham roll.     

Effect of level, source, and time of feeding prior to slaughter of supplementary dietary magnesium on pork quality

A total of 192 pigs were utilized in a 2×3×3 factorial arrangement with an additional control treatment. The treatments were: (1) magnesium level (1.6 vs. 3.2 g of magnesium pig(-1) day(-1)); (2) magnesium source (sulfate vs. proprionate vs. proteinate); (3) feeding duration (5 vs. 2 vs. 1 day), and a control (no supplementary magnesium). Minolta L(?) values were lower (P?0.05), indicating darker muscle color, for pigs supplemented with 1.6 g magnesium pig(-1) day(-1) compared to the controls while pigs on the 3.2 g magnesium level were intermediate between these two treatments. Animals on the 1 day treatment had a higher (P?0.05) ultimate pH and lower (P?0.05) Minolta L(?) compared to those on the 2 days and control treatments, while 5 days pigs were intermediate and had lower L(?) values compared to the controls. The sulfate and proteinate treatments produced pork with the lower (P?0.05) Minolta L(?) values compared to the controls. Pigs fed the sulfate diet had a lower (P?0.05) drip loss compared to those on the control treatment. Results from this study suggest that the lowest level (1.6 g magnesium pig(-1) day(-1)) and the shortest time of supplementation (1 day) may be effective in improving pork color and water-holding capacity.     

The Effects of Irradiation at 1.6 kGy on Quality Characteristics of Commercially Produced Ham and Pork Frankfurters over Extended Storage

ABSTRACT: Commercially produced sliced ham and all-pork frankfurters were obtained from a national meat processor and irradiated at 1.6 kGy. The samples were evaluated for color, lipid oxidation, odor, flavor, and the production of volatiles over an 8-wk storage period. Irradiation processing did not affect color values for the ham or frankfurters. Lipid oxidation as measured by 2-thiobarbituric acid-reactive substances (TBARS) did not increase for either the ham or frankfurters. Irradiation processing increased off-odor scores for the ham but not for frankfurters. On the other hand, off-flavor scores were not significantly different for ham but were higher in frankfurters after irradiation processing. Dimethyl disulfide content increased as a result of irradiation in both the ham and frankfurters but decreased during the 8-week storage period. Irradiation processing resulted in the formation of new volatile compounds in the ham samples including heptane, trans -1-butyl-2-methylcyclopropanone, 2-octene, and toluene, which were not present in nonirradiated ham. In the case of frankfurters, irradiation treatment resulted in the formation of 2-butanone, which was not present in the nonirradiated frankfurters. Most volatile compounds that were affected by irradiation processing of either the ham or frankfurters were increased when compared with nonirradiated controls. Although color and lipid oxidation (TBARS) did not seem to be affected by irradiation processing at 1.6 kGy, changes in odor, flavor, and the production of volatiles are of concern if irradiation is to be used to control microbial growth in ready-to-eat pork products.     

EFFECTS OF INJECTION OF A DILUTE PHOSPHATE-SALT SOLUTION ON PORK CHARACTERISTICS FROM PSE, NORMAL AND DFD CARCASSES

Phosphate-salt pump effects were evaluated on sensory characteristics of pale, soft, exudative (PSE) pork, normal and dark, firm and dry (DFD) pork. Water-holding capacity, instrumental color (L*, a*, b*), pH, and muscle color scores were determined at 24 h postmortem on pork loin pairs (n=21 pairs). Based on color score, paired loins were assigned to PSE, normal or dark, firm, dry groups. PSE muscles were lighter, redder and more yellow than normal or DFD muscles; hue angle indicated that DFD muscles were actually closer to the true red axis of the CIE Lab Color Space. Drip and purge losses were higher (p<0.05) in PSE muscles. Paired loins were pumped with water (controls) or 0.3% tripolyphosphate solution (0.25% salt) to 110% of original weight, vacuum packaged, frozen, cut into chops, and cooked to 70 or 80C. Phosphate-salt pumped loins were juicier and more tender (p<0.05) than water-pumped loins regardless of muscle condition. Loins cooked to 70C were juicier, were more tender (sensory) but required more force to shear than those cooked to 80C.     

Benchmarking value in the pork supply chain: Characterization of US pork in the retail marketplace

Retail pork from eight US cities was obtained for quality and palatability evaluations. Boneless pork loin chops were classified into one of three quality categories - "high," "average," or "low" - with higher quality chops possessing more desirable color, marbling, juiciness, and shear force characteristics than lower quality chops. Loin chops that were enhanced (injected with solution to improve juiciness and/or tenderness) had higher (P<0.05) pH, less purge and cook loss, and higher palatability ratings compared to non-enhanced chops. Hams compared by their protein fat free (PFF) classifications showed that ham and water product received the highest (P<0.05) ratings for juiciness and tenderness, and ham with natural juices received the highest (P<0.05) texture, ham flavor intensity, and smoke flavor ratings. Bacon was compared by price/brand categories; however, the highest priced, national branded bacon (US$12.03/kg) was similar (P>0.05) for most quality and all palatability traits to the lowest priced, national branded bacon (US$6.47/kg) and the store branded bacon (US$8.30/kg) even though retail prices differed widely. Overall, there were tremendous ranges in values for these products indicating that retail pork is quite variable and that efforts to improve the quality and consistency of it must continue.     

Effects of gamma-ray,electron-beam,and X-ray irradiation on physicochemical properties of heat-induced gel prepared with salt-soluble pork protein

The objective of this study was to investigate the physicochemical and textural properties of heat-induced gels prepared with pork muscles irradiated with gamma rays, electron beams, and X-rays. Pork muscles were irradiated at 5 kGy using the different irradiation sources, and heat-induced gels were prepared from the irradiated pork muscles at a protein concentration of 5 mg/mL. Each irradiation treatment produced lower water-holding capacity, protein solubility, apparent viscosity, hardness, springiness, cohesiveness, gumminess, and chewiness than the control gel prepared with non-irradiated pork muscle (P < 0.05). In addition, gamma irradiation was more influential than electron or X-ray irradiation on the negative impacts on water-holding capacity and texture of heat-induced gels. Therefore, this study suggests that the irradiation source could be one of the significant factors affecting gelling properties of irradiated meat.     

Benchmarking value in the pork supply chain: Processing and consumer characteristics of hams manufactured from different quality raw materials

Impact of fresh ham quality on finished ham product characteristics was evaluated. Bone-in hams destined for spiral-sliced ham manufacturing were sorted into two pH groups before processing: pH ⩽ 5.5 and pH ⩾ 5.6. For boneless hams, raw materials were sorted into groups with different levels of pale, soft, and exudative (PSE) product before manufacturing into sliced vacuum packaged hams: “Low PSE” (⩽5% PSE muscle), “Intermediate PSE” (20–30% PSE muscle) or “High PSE” (40–60% PSE muscle). Few differences were observed between the pH ⩽ 5.5 and pH ⩾ 5.6 groups in objective color measures and drip loss in bone-in spiral-sliced hams stored under refrigeration, however, after frozen storage, hams from the pH ⩽ 5.5 group had lower L*- and a*-values and had much higher drip loss than those from the pH ⩾ 5.6 group. Processing yields for bone-in spiral-sliced hams were similar through cooking and chilling, however, the pH ⩾ 5.6 group had higher yields after slicing. For boneless hams, defects occurred at a greater frequency in hams formulated with a greater percentage of PSE raw materials than those with lower amounts of PSE. Differences in objective color measures and purge were minimal over the duration of storage time, but hams formulated with greater percentages of PSE raw materials were lighter in appearance and had less redness. Consumers gave lower color responses for hams formulated with “High PSE” amounts, but did not differentiate between hams manufactured with lower quantities of PSE muscle. However, when consumers directly compared packages of ham, there was distinct discrimination against hams manufactured with greater amounts of PSE. Purchase intent showed that consumers favored ham manufactured from fresh ham muscles containing low quantities of PSE tissue. Further research is needed to determine the optimal ratio of allowable PSE product in formulation that enables processors to maximize consumer appeal with the economic realities of sorting out PSE pork.     

Association of single nucleotide polymorphism (SNP) markers in candidate genes and QTL regions with pork quality traits in commercial pigs

Numerous reports have described genetic markers or genomic regions (QTL) associated with pork quality and/or palatability but few validation studies have been reported. Therefore, 156 SNP markers from 45 candidate genes and eight QTL regions were analyzed for association with pork quality and palatability traits from 888 pork loins. Loins were collected at three slaughter facilities and selected to represent a wide range of pork color, pH and marbling. Phenotypic data recorded included objective and subjective measures of color and marbling, purge loss, shear force, and cooking loss. Data were analyzed with SAS PROC MIXED where loin was fit as a random effect. Results indicated some of the markers tested should be useful in industry, while others are not segregating in all populations or linkage disequilibrium between markers and causative genetic variation fluctuates among populations limiting their universal utility. Genes with the largest effects on pork quality were MC4R, IGF2, CAST and PRKAG3.     

Association of single nucleotide polymorphism (SNP) markers in candidate genes and QTL regions with pork quality traits in commercial pigs

Numerous reports have described genetic markers or genomic regions (QTL) associated with pork quality and/or palatability but few validation studies have been reported. Therefore, 156 SNP markers from 45 candidate genes and eight QTL regions were analyzed for association with pork quality and palatability traits from 888 pork loins. Loins were collected at three slaughter facilities and selected to represent a wide range of pork color, pH and marbling. Phenotypic data recorded included objective and subjective measures of color and marbling, purge loss, shear force, and cooking loss. Data were analyzed with SAS PROC MIXED where loin was fit as a random effect. Results indicated some of the markers tested should be useful in industry, while others are not segregating in all populations or linkage disequilibrium between markers and causative genetic variation fluctuates among populations limiting their universal utility. Genes with the largest effects on pork quality were MC4R, IGF2, CAST and PRKAG3.     

The effects of aging on moisture-enhanced pork loins

The effects of preinjection aging time on pork loins injected with a salt/phosphate/lactate solution were investigated. Ninety-six fresh pork loins, in two replicates, were divided into two treatments. Loins in the first treatment were injected to 13% of loin weight at 1 day post-slaughter with a brine containing 2.17% salt/3.04% phosphate/20.8% lactate. The second group was injected with the same brine 4 days after slaughter. Color and Warner-Bratzler shear (WBS) force were measured immediately, 7 and 14 days after injection. Purge was measured 8 and 15 days postmortem. Western blots to measure troponin-T degradation were performed on samples from the two loins that resulted in the lowest shear force, and from the two loins that resulted in the highest shear force, as measured by Warner-Bratzler shear. The two loins with the most purge loss and the two loins with the least purge loss were also analyzed by Western blots for desmin degradation. The L(?) and b(?) color values were higher (P<0.05) and purge was greater (P<0.05) for loins injected 1 day postmortem than for loins injected 4 days postmortem. Western blots demonstrated that injection did not affect protein degradation. Therefore, differences between individual animals that affect protein degradation remain important regardless of injection treatment.     

Prediction of color and pH measurement throughout boneless center-cut pork loins

Boneless pork loins (N=95) divided into three groupings based on National Pork Producers Council color standards were utilized to characterize changes in color and pH throughout the loin. CIE L(?), CIE a(?), CIE b(?), saturation, and hue angle differed (P<0.05) for color category and chop position. A color category by position interaction (P<0.05) existed only for pH values. These differences in color and pH measures throughout the loin indicate that one measurement may not characterize the entire boneless loin. For all color and pH measures significant orthogonal and polynomial contrasts existed, therefore, separate regression equations were developed for each color category to predict position response. Multiple regression equations were significant for most objective measures of color and pH, but the low R(2) values indicate that these models provide little information as to changes in color and pH throughout the boneless pork loin.     

植物油预乳状液替代猪脂肪对法兰克福香肠品质特性的影响

将1 g/100 mL氧化绿原酸添加到以猪血浆蛋白水解物作为乳化剂所制备的水包油型乳状液中,以此获得高稳定性的植物油预乳状液。然后将该预乳状液以15%、30%、45%和60%的比例替代猪脂肪加入到法兰克福香肠中,探讨替代脂肪比例对香肠品质特性的影响。测定香肠的蒸煮损失、质构、色度以及水分迁移规律,同时测定肉糜的乳化稳定性和流变特性。结果表明,随着预乳状液替代比例的增加,香肠的蒸煮损失显著降低（P＜0.05）,硬度、咀嚼性、L*值和b*值显著增加（P＜0.05）,而弹性、黏结性、感官评价无显著变化（P＞0.05）。低场核磁研究结果发现,预乳状液替代比例的增加能够显著缩短香肠的弛豫时间（P＜0.05）,说明其能增强蛋白质网络对水分子的束缚能力。与此同时,随着预乳状液替代比例的增加,肉糜的乳化稳定性显著增加（P＜0.05）。另外,肉糜的流变学测定结果表明,随着预乳状液替代比例的增加能够显著提高肉糜在加热终点的储能模量（G’）和损失模量（G′′）,而且显著降低了相位角正切值（tanδ）（P＜0.05）。在法兰克福香肠的制作中猪脂肪能够被预乳状液部分替代,而且对香肠的感官无显著影响,尤其以45%的替代量为最佳。     

超高压对低盐海藻鸡肉糜品质的影响

为探究超高压对低盐海藻鸡胸肉糜的影响,考察了不同压力（0.1～500 MPa/10 min）和保压时间 （0～25 min/300 MPa）时肉糜的色泽、盐溶蛋白溶解度、蒸煮损失率、持水性、冻融损失率、质构以及流变特 性的变化规律。结果表明：随着压力的升高,肉糜亮度（L*）和白度（W）先降低后增加,在200 MPa时最低, 红度（a*）逐渐上升;100～300 MPa超高压处理对盐溶蛋白溶解度无显著影响（P＞0.05）,压力大于300 MPa 时盐溶蛋白溶解度显著降低（P＜0.05）;蒸煮损失率和冻融损失率随压力的升高呈先降低后增加趋势,在压力 为300 MPa时达到最低值;与0.1 MPa处理组相比,100～500 MPa压力处理使肉糜持水性显著升高（P＜0.05）; 硬度和弹性随着压力的增加先升高后降低,在200～300 MPa时达最大值,200、300 MPa处理组间无显著差异 （P＞0.05）;与0.1 MPa处理组相比,超高压处理能够改善海藻鸡胸肉糜的储能模量（G’）和相位角正切值 （tan δ）。保压时间对低盐海藻鸡胸肉糜色泽、盐溶蛋白溶解度、蒸煮损失率无显著影响（P＞0.05）;随着保压 时间的延长,肉糜的持水性、G’、tan δ值和质构得到改善,但保压时间过长（25 min）可破坏肉糜的硬度和弹性。 本研究表明超高压处理能够改善低盐海藻鸡胸肉糜的品质,为新型肉制品的开发提供了理论依据。     

Quality characteristics of reduced-fat frankfurters with pork fat replaced by sunflower seed oils and dietary fiber extracted from makgeolli lees

The effects of reducing pork fat levels from 30% to 20% by partially substituting pork fat with a mix of sunflower seed oil (0, 5, 10, 15, and 20%) and makgeolli lees fiber (2%) were investigated based on physicochemical properties, textural properties, and sensory characteristics of reduced-fat frankfurters. The moisture and ash content, and lightness were higher in reduced-fat frankfurter samples containing sunflower seed oil and makgeolli lees fiber than in the control. The results showed that reduced-fat frankfurter samples with higher sunflower seed oil levels had lower redness and yellowness values, as well as less cooking loss, emulsion stability, hardness, springiness, and apparent viscosity. The results of this study show that incorporating sunflower seed oil and makgeolli lees fiber into the formulation successfully reduced animal fat in frankfurters, while improving quality characteristics.     

RAW MATERIAL pH, PUMP LEVEL AND PUMP COMPOSITION ON QUALITY CHARACTERISTICS OF PORK

ABTRACT
Boneless, paired pork loins (n=120) were selected based on pH at 14 h postmortem. Ultimate pH, drip loss, instrumental color (L*, a*, and b* values), and proximate analysis were determined prior to pumping. Paired loins were cut into four sections and pumped to 100%, 106%, 112% or 118% of original weight to result in a product containing 0.4% sodium tripolyphosphate (STP) for Experiment 1 (Exp. 1) and 0.4% STP plus 0.4% salt for Experiment 2 (Exp. 2). In Exp. I, additional pump level increased (P<0.05) vacuum package purge. Higher raw materials pH reduced purge. A pump level x pH interaction (P<0.05) occurred for cook loss at 70C. In Exp. 2, increased raw materials pH reduced (P<0.05) purge loss and resulted in juicier, more tender pork. Pumped pork had higher (P<0.05) tenderness, juiciness, and saltiness scores than controls.     

Effects of dietary magnesium and duration of refrigerated storage on the quality of vacuum-packaged, boneless pork loins

Quality data were initially collected on 78 pork loins from crossbred pigs fed diets containing 0, 1.25 or 2.5% magnesium mica (MM). Loins were then vacuum-packaged, and randomly assigned to either 4 or 8 weeks of storage at 2°C. Dietary MM had no (P > 0.05) effect on moisture loss/retention or subjective and objective color measurements. Purge volume increased (P<0.05) and drip loss decreased (P<0.05) as storage time increased. Moreover, longissimus thoracis et lumborum (LM) chops became lighter (P<0.05), redder (P<0.05), and more yellow (P<0.05) during 8 weeks of storage. Although TBARS values increased linearly (P<0.001) during extended storage, LM chops from pigs fed 2.5% MM tended to have lower (P<0.07) TBARS values after 4 weeks of storage than chops from pigs fed 0 and 1.25% MM. After 8 weeks of storage, however, there was a tendency for TBARS values of chops from pigs fed 1.25% MM to be lower (P<0.07) than chops from pigs fed 2.5% MM. Even though feeding swine diets containing MM did not affect color and water-holding capacity of pork loins during storage, the data indicated inclusion of MM in swine diets may retard onset of oxidative rancidity in vacuum-packaged pork loins.     

Evaluating an objective method to measure fresh pork loin firmness

The purpose of this study was to develop an objective method for measuring fresh pork loin firmness. A total of 42 fresh boneless pork loins were collected from a range of subjective firmness scores based on the whole boneless loin to create a population suitable for creating a prediction equation. Loins were subjectively scored by panelists prior to objectively being measured with a Texture Analyzer. An R(2) value of 0.54 was achieved for the prediction equation that was generated. A second trial was performed to test the equation resulting in an R(2) value of 0.30 concerning subjective and objective values. The results from these studies indicate that it is possible to create a standardized protocol in order to determine objective firmness that would be useful for future studies and for the development of hand held or online firmness measuring devices.     

脂肪含量对低盐猪肉凝胶品质的影响

以未添加磷酸盐的低盐猪肉凝胶作为研究对象,考察脂肪添加量(0～20%)对猪肉凝胶保水、质构和色泽的影响。结果显示,脂肪添加量在15%～20%范围内,凝胶保水性显著增加(P<0.05);添加5%以上的脂肪,可显著提高猪肉凝胶的L*值(P<0.05);在脂肪添加量不高于5%条件下,猪肉凝胶可形成良好的硬度、弹性、凝聚性和咀嚼性,并能保持较好的红度值(a*值),利于开发低脂猪肉制品。