Hot Pork Processing, Brine Chilling and Mechanical Portioning as a Fresh Pork Processing System

Rapid chilling was investigated as a link between hot pork processing and mechanical portioning. Loins from market weight hogs (n = 40) were removed (pre- or post-rigor) and were assigned to one of two chilling treatments (brine chilling or blast freezing). Loins were chilled until crust frozen, then tempered, pressed and cleaved. Ultimate pH, cooking yields, taste panel ratings and Warner-Bratzler shear force values (WBS) were obtained. Pre-rigor chops had significantly higher WBS values and lower (less tender) taste panel ratings than post-rigor chops. Generally, pre-rigor chops were juicier but less tender. There were no major differences between rapid chilling treatments nor in ultimate pH or cooking data. Less severe chilling techniques are needed to make this processing system feasible.     

Effect of Rapid Chilling and Accelerated Processing on the Physical and Sensory Characteristics of Cured Pork Bellies

The effects of accelerated and conventional processing systems on the physical and sensory characteristics of cured pork bellies were investigated using three accelerated processing systems. Accelerated processing, with or without electrical stimulation, was effective in producing bellies and bacon strips equal to or superior to those which were conventionally processed. Non stimulated accelerated processing samples were evaluated as being less crispy than other treatments. Rapid chilling in conjunction with accelerated processing, with or without the aid of electrical stimulation, can produce cured bellies as well as bacon slices that are comparable in all traits with bellies from conventionally processed carcasses.     

Processing Properties of Pork as Affected by Electrical Stimulation, Post-Slaughter Chilling and Muscle Group

Left sides of 30 slaughtered pigs were electrically stimulated (ES); right sides were not stimulated (NES). Sides were placed in a conventional cooler (24 hr) or blast freezer (3 hr) or showered with a brine solution (15.8% salt, -5.6°C for 3 hr). Twenty-four hr postmortem, picnic shoulders were removed, dissected into four muscle groups and determinations made for certain processing properties. ES decreased (P < 0.05) pH values for predominantly white muscles, increased (P < 0.05) juice loss during cooking for shank muscles and decreased (P < 0.05) percentages of salt-soluble protein (SSP) for both predominantly red and shank muscles. Other muscle properties were not affected by ES. Rapid initial chilling did not affect (P > 0.05) processing properties of muscle groups.     

宰后放置时间和冷冻对中式香肠品质的影响

采用均匀试验设计,以宰后放置时间和是否冷冻为考察因素,以猪肉为原料进行香肠加工,探讨宰后放置时间和是否冷冻对香肠品质的影响规律。结果表明：宰后放置时间和是否冷冻对中式香肠的感官评分没有显著影响;对pH 值、原料肉系水力、生香肠的硫代巴比妥酸反应物(TBARS)值和出品率有显著影响,且均呈非线性关系。进行优化计算得到：当所选用的原料为冷冻肉时,暂未找到共同解;当所选用的原料为未经冷冻的肉样时,宰后冷冻时间越早,出品率越大,生香肠的TBARS 值越小。因而以鲜肉为原料制作香肠,所选原料越新鲜,香肠品质越好。     

超快速冷却结合不同包装贮藏对冷鲜猪肉品质的影响

为探究超快速冷却(冷却速度14.43℃/h)结合不同包装方式对贮藏猪肉品质的影响,对超快速冷却处理的猪背最长肌分别进行有氧托盘包装、气调包装(50%O₂+50%CO₂)、真空包装和真空收缩包装,分析猪背最长肌在(-1.0±0.5)℃贮藏过程中pH、肉色、蒸煮损失、质构特性、菌落总数、挥发性盐基氮和脂肪氧化的变化,以期明确超快速冷却结合4种包装的猪肉在贮藏期间的品质变化规律。结果表明,在贮藏30 d时,超快速冷却结合气调包装猪肉红度值a^*(3.62)高于超快速冷却结合有氧托盘包装(3.35)、真空包装(3.20)和真空收缩包装(1.66)的猪肉;超快速冷却结合真空包装和真空收缩包装的猪肉蒸煮损失分别为20.82%和21.83%,显著低于有氧托盘包装和气调包装的猪肉(P <0.05);真空收缩包装猪肉的菌落总数、挥发性盐基氮和脂肪氧化程度分别为4.92 lg(CFU/g),9.69 mg/100 g和0.77 mg MDA/kg,显著低于其它3种包装猪肉(P <0.05)。与有氧托盘包装相比,真空包装、真空收缩包...     

Discoloration of Fresh Pork as Related to Muscle and Display Conditions

Pale, soft, exudative (PSE), normal, and dark, firm, dry (DFD) pork was held 7 days at 4°C under light or dark then color was evaluated instrumentally and visually. Change in reflectance (R630-R580) was used to estimate color changes due to oxymyoglobin. PSE pork was lighter (high L*) than normal and DFD pork, but did not change over time. An increase in a* and R630-R580 occurred the first day for normal and DFD, but not for PSE samples. A subsequent increase in hue angle and decrease in R630-R580 (loss of redness) occurred in PSE and normal, but not in DFD samples. Changes in hue angle and R630-R580 were more rapid in PSE than in normal samples. Light exposure accelerated all changes except L*. Visual redness inversely correlated with L* value.     

乳过氧化物酶体系在冷却猪肉保鲜中的应用研究

为了评定乳过氧化物酶体系对冷却猪肉的保鲜效果,对冷却鲜猪肉分别采用浓度为3μg/ml的乳过氧化物酶体系(LPS)、4μg/ml的LPS、40μg/ml的乳酸链球菌素(Nisin)、3μg/ml的LPS+40μg/ml的Nisin、4μg/ml的LPS+40μg/ml的Nisin等5组不同保鲜剂处理,以蒸馏水处理做对照,测试猪肉在3±0.5℃保存条件下感官指标、理化指标和细菌总数的变化。结果表明:经LPS处理的冷却猪肉在贮藏过程中的感官指标、理化指标和细菌总数的变化比对照组缓慢,差异达到极显著水平(p<0.01),LPS可有效延长冷却猪肉的保鲜期;LPS处理比Nisin处理的保鲜效果更好,差异达到显著水平(p<0.05);当LPS与Nisin复配时,可以达到更好的保鲜效果,猪肉的保鲜期可达20d以上;Nisin可以减轻LPS导致的猪肉脂肪氧化。     

预冷环境及时间对猪胴体冷却损耗的影响

为了解决传统企业在猪胴体冷却过程中干耗较严重的问题,在春季选取若干宰后猪胴体,研究预冷库内不同位置的风速、温度、相对湿度的变化规律,不同冷却时间和冷库内不同位置对猪胴体冷却损耗的影响。结果表明：预冷库内不同位置之间的风速、温度、相对湿度之间差异对猪胴体预冷损耗存在显著影响（P＜0.05）,风速大的位置其胴体周围环境相对湿度高,温度低,胴体冷却损耗小;随着预冷时间的延长,猪胴体损耗逐渐增大,且预冷时间对冷却损耗也有显著影响（P＜0.05）。     

低温等离子体冷杀菌处理时间及电压强度对生鲜猪肉脂质氧化的影响

以生鲜猪肉中提取的脂质为试样,采用聚对苯二甲酸乙二醇酯/聚乙烯（polyethylene terephthalate/polyethylene,PET/PE）构成的双层复合材料空气包装,以电压强度及处理时间为实验因素,研究不同温度下低温等离子体冷杀菌处理条件对生鲜猪肉脂质氧化的影响,并通过构建动力学模型分析其对脂质一次氧化和二次氧化活化能（activation energy,Ea）的影响。结果表明：一定程度的低温等离子体处理（电压小于80?kV、时间小于80?s）时,处理时间、电压强度及贮藏温度对肌肉脂质一次及二次氧化均有显著的促进作用,并且电压强度对脂质氧化的影响大于处理时间。另外,低温等离子体处理时间及电压强度的增加均可显著降低脂质二次氧化所需的Ea;脂质一次氧化所需Ea随电压强度的增加而降低,随处理时间的延长呈现抛物线变化趋势（y＝－0.005?3x2＋0.464?1x＋20.684（R2＝0.974?4））;处理时间为43.8?s时,一次氧化所需的Ea最高,为30.84?kJ/mol。当电压强度为30～80?kV、处理时间为30.7～80.0?s时,二次氧化所需的Ea低于一次氧化,肌肉脂质更容易发生二次氧化。采用低温等离子体冷杀菌设备处理生鲜猪肉使脂质更容易发生氧化,或可作为促进脂质氧化的一项新技术,适用于低温贮藏短时处理猪肉产品。     

Effects of Packaging and Processing Procedures on the Quality and Shelf Life of Fresh Pork Loins

Thirty crossbred hogs were slaughtered and the longissimus muscle from the left side was removed and divided into two equal sections within 20 min postmortem (HP) and those from the right side were removed and divided 24 hr postmortem(CP). One-half of the muscle from each side was wrapped in parchment paper (PP) and the other half was vacuum packaged (VP) and loin sections were assigned to storage intervals of 0, 7, 14, 21, or 28 days. At the end of each storage period, loins were evaluated for moisture loss, bacterial levels, off-odor, sensory properties and retail case display. VP and HP treatments had reduced moisture loss (P<0.05). Off-odor scores were higher (P<0.05) for PP wrapped loins on day 14. Few palatability differences were observed with packaging and processing treatments. Vacuum packaging had positive effects on the storage and retail display characteristics of fresh pork.     

Consumer-rated Quality Characteristics as Related to Purchase Intent of Fresh Pork

Consumers (n=556) rated pink color, wet/dry appearance, overall acceptability and purchase intent of normal, pale, soft and exudative (PSE), and dark, firm and dry (DFD) pork loin slices in PVC packages in five retail supermarkets. DFD samples appeared driest and PSE samples appeared wettest. Samples in the higher ranked two purchase intent categories appeared more wet than those in the lower three categories. The pinker PSE samples and all DFD samples were in the higher ranked purchase intent categories. Purchase intent generally paralleled overall acceptability; however, prediction equations indicated that wet/dry appearance, color and overall acceptability all contributed to purchase intent decision depending on muscle condition.     

Konjac Flour Gel as Fat Substitute in Low-fat Prerigor Fresh Pork Sausage

Prerigor trimmings from four lean cuts of pork carcasses (n = 3) were used to manufacture three replications of low-fat (10%) fresh pork sausage containing konjac flour gel, at 0, 10 or 20% levels and compared to a 40% fat control. Treatment sausages showed equal or improved cooked yields, slightly higher shear force (kg/g) and sensory textural attributes, but rated slightly lower in juiciness. As konjac flour gel levels increased, shear force and sensory textural attributes became more like the control. Storage time had minimal effect on quality and shelf life. Acceptable low-fat, prerigor pork sausage can be produced with 10–20% incorporation of konjac flour gel.     

Retail Display Lighting Type and Fresh Pork Color

The effects of lighting type on fresh pork color were studied by displaying chops under delux cool white (DCW), cool white, Surlyn® coated (CWSC), or warm white (WW) fluorescent or cool flood (CF) incandescent lights. Initial color desirability was assessed. Hunter colorimeter values and percentage myoglobin (Mb), oxymyoglobin (OMb) aand metmyoglobin (MMb) were determined over 5 days of display. Light types CF and DCW provided the most desirable color rendition. Chops displayed under CF lights became darker, had less percentage OMb and greater Mb, and likely had greater microbial growth than other chops due to an increase in chop temperature. It appears that CF and DCW lights provide the most desirable color and that precautions against temperature elevation are needed.     

Acceptability and Shelf-life of Marinated Fresh and Precooked Pork

Fresh (FL) and precooked (PL) longissimus chops and fresh semi-membranosus/adductor (SM) roasts were evaluated to determine acceptability of marinated pork. Citric acid and sodium acid pyrophosphate lowered pH (CAP), sodium acid pyrophosphate attained intermediate pH (SAP), and sodium tripolyphosphate increased pH (TPP). In FL and SM cuts, TPP improved sensory characteristics, water-holding capacity (WHC) and processing yields. CAP reduced microbial growth in FL chops and improved tenderness in SM roasts. In PL cuts, TPP improved juiciness and reheating yields. Marinating at low pH reduced microbial growth; marinating at high pH improved sensory properties, WHC, fresh pork processing yields and precooked pork juiciness and reheating yields.     

冷却猪肉初始菌相分析与冷藏过程中的菌相变化规律研究

本文采用选择性培养基对托盘包装冷却猪肉的初始菌相进行了分析,并研究了在0、2、5和7℃储藏温度下的菌相变化规律。结果表明:假单胞菌、热死环丝菌、肠杆菌科和乳酸菌是构成有氧条件下冷却猪肉初始菌相的主要微生物。在不同的储藏温度下,细菌总数均有不同程度的增长。假单胞菌在所研究的温度下均与细菌总数相当,增长速度最快。热死环丝菌和肠杆菌也有不同程度的增长,在实验时间的末期也达到了较高的对数值。     

宰前处理和冷却方式对猪肉品质的影响

本文对宰前处理方式、致晕方法和冷却方式对猪肉品质(肉色、滴水损失/持水性-WHC和电导率)的影响进行了比较总结,旨在对屠宰行业在控制肉品质,减少PSE发生方面提供参考。     

质谱法评价猪肉新鲜度

目的 建立一种可用质谱法评价猪肉新鲜度的检测方法。方法 通过顶空固相微萃取–气相色谱–质谱联用(HS-SPME-GC-MS)方法对不同新鲜度猪肉的挥发性成分进行检测分析, 根据猪肉挥发性物质的特性指纹图谱, 采用欧氏距离平方计算猪肉样品间的相似系数, 采用组间平均连接距离方法进行聚类分析。结果 不同新鲜度的猪肉的挥发性成分有较大差异, 新鲜猪肉选取18个共有峰, 次新鲜猪肉选取30个共有峰, 变质猪肉选取25个共有峰。结论 通过指纹图谱技术和聚类分析检验猪肉新鲜度是一种客观可行的新技术。     

HACCP与冷却肉加工技术

本文阐述了HACCP的概念和原则及其在冷却肉生产中的应用,着重介绍了肉类冷却工艺的几种不同处理方式.     

肉类的冻结加工技术与经济分析

肉类的冻结加工技术有两阶段冻结工艺和直接冻结工艺等.通过试验对比认为,直接冻结工艺优于两阶段冻结工艺,且对提高冷藏企业的经济效益有一定的积极作用.