油煎猪肉饼中6 种氨基咔啉类杂环胺的检测方法及加工条件对其生成的影响

建立一种同时测定油煎猪肉饼中6 种氨基咔啉类杂环胺（2-氨基-3-甲基-9H-吡啶并[2,3-b]吲哚、2-氨基-9H-吡啶并[2,3-b]吲哚、1-甲基-9H-吡啶并[3,4-b]吲哚、9H-吡啶并[3,4-b]吲哚、3-氨基-1,4-二甲基-5H-吡啶并[4,3-b]-吲哚和3-氨基-1-甲基-5H-吡啶并[4,3-b]吲哚）的超高效液相色谱-四极杆/静电场轨道阱高分辨质谱检测方法,并研究加工条件对猪肉饼中6 种氨基咔啉类杂环胺生成的影响。结果表明,待测杂环胺的最优提取和净化条件为：1 g样品中添加1.5 g NaCl、10 mL 1 mol/L NaOH溶液-乙腈（4∶6,V/V）提取,StrataTM-X-C柱净化,4 mL甲醇-氨水（90∶10,V/V）洗脱。6 种杂环胺在相应质量浓度范围内线性良好,相关系数均大于0.996,方法检出限和方法定量限分别为0.02～0.15 μg/kg和0.05～0.5 μg/kg,回收率为64%～91%。油煎5 min后生成的6 种杂环胺含量为9.50 μg/kg。选用菜籽油、复合涂层锅、猪肉饼直径4 cm加工条件下,6 种杂环胺生成量最高,分别为47.62、76.83 μg/kg和29.33 μg/kg。     

基于低场核磁共振技术的冷冻猪背最长肌品质变化研究

采用低场核磁共振技术、核磁成像技术和一维空间频率编码技术,研究猪背最长肌在-18℃冻藏0d和1,3,6,9,12,15个月后水分含量和迁移变化规律;并测定猪肉贮藏过程中TVB-N、TBARS、汁液流失率、蛋白质溶解度的变化,将水分变化和品质指标变化进行相关性综合分析。结果表明:猪背最长肌中3种组分的水分分别为:结合水(T_(20))、不易流动水(T_(21))和自由水(T_(22)),随着冻藏时间的延长,肉样中T_(21)组分降低,T_(22)组分增加;MRI表明随着时间的延长,样品水分分布从最初分布均匀到样品边缘信号强,中间部位信号低。随着冻藏时间的再延长,又逐渐恢复均匀状态,15个月后水分分布较均匀;用一维频率编码扫描发现随着冻藏时间的延长,肉中水分的信号量(幅值)逐渐降低;相关性分析结果表明:T_(21)与冻藏时间、TVB-N、TBARS、汁液流失率、蛋白质溶解度都显著相关(P0.05),T_(22)与冻藏时间、TVB-N极显著相关(P0.01),T_(22)与TBARS、汁液流失率、蛋白质溶解度显著相关(P0.05),T_(21)、T_(22)都与肉中品质指标呈现较好的相关性。     

微生物和理化特性影响

本文研究不同包装方式对调理预制烤猪肉冰温（-1 ℃）贮藏中微生物和理化特性的影响。结果表明,-1 ℃冰温贮藏28 d后托盘包装样品的细菌总数（7.53 lg cfu/g）显著高于真空包装样品的细菌总数（5.54 lg cfu/g）（P<0.05）,其优势腐败菌为假单胞菌和热杀索丝菌。真空包装样品优势菌为热杀索丝菌、乳酸菌和假单胞菌。贮藏28 d后,托盘包装的样品红度（a*）值为9.88、pH为6.37、硫代巴比妥酸（TBARS）值达到了3.02 mg/kg、挥发性盐基氮（TVB-N）值为56.6 mg/100 g、感官基本不可接受,而真空包装的a*值为10.87、pH为6.13、TBARS值为1.62 mg/kg、TVB-N值为43.9 mg/100 g、感官仍有一定的可接受性。SDS?聚丙烯酰胺凝胶电泳结果表明贮藏期间真空包装样品的所有蛋白条带的强度强于托盘包装的样品,直到贮藏结束时,真空包装样品的蛋白条带仍然较粗且清晰。研究表明冰温结合真空包装可有效的延长调理预制烤猪肉的保质期。     

Antioxidant Activity of Phosvitin in Phosphatidylcholine Liposomes and Meat Model Systems

ABSTRACT: Phosvitin, an iron-chelating protein, was tested for its ability to inhibit lipid oxidation in phosphatidylcholine (PC) liposomes and meats. Inhibition of thiobarbituric acid reactive substances (TBARS) formation increased with increasing phosvitin concentrations with maximal inhibition occurring at 40 and 15 mM in PC liposomes and pork muscle homogenates, respectively. Phosvitin lost only 2 to 15% of its antioxidant activity after being heated for 10 min at 60 to 100 °C. The ability of phosvitin to inhibit TBARS formation was maximal at pH 7.0. Phosvitin was a more effective antioxidant in cooked ground pork with 20 mM inhibiting 11 to 39% of oxidation compared with 0 to 20% inhibition in uncooked, salted ground pork containing 60 mM phosvitin.     

Biogenic Polyamines Affect Activity of Aminopeptidase B and Alanyl Aminopeptidase from Porcine Skeletal Muscle

The effect of biogenic polyamines (agmatine, cadaverine, putrescine, spermidine, and spermine) on the activity of pork muscle aminopeptidase and alanyl aminopeptidase was investigated. Agmatine (5 mM) showed a powerful inhibitory effect for both enzymes (more than 50% inhibition). Cadaverine and less intensely putrescine showed similar inhibitory effects for both enzymes. All assayed polyamines inhibited activity of both aminopeptidases except spermine and spermidine which did not affect aminopeptidase B. Thus, one of these inhibitors could be used to avoid the interference of alanyl aminopeptidase when assaying aminopeptidase B in muscle extracts.     

Quality characteristics of Chinese sausages made from PSE pork

Chinese sausages made from normal and different levels of PSE pork (100% Normal, 50%Normal+50% PSE and 100% PSE) were vacuum-packaged and stored at 4 °C for 45 days. The composition, processing yield, pH value, thiobarbituric acid (TBA) value, water activity, lactic acid bacteria counts and sensory properties of the meat products were evaluated. PSE pork loins had lower pH value, water holding capacity, moisture, fat and myofibrillar proteins content, but higher L^* value, drip loss and protein content than normal pork. Sausages made from 100% PSE pork had lower pH value, processing yield, moisture and fat content, but higher protein content than those of the 100% Normal and the 50% Normal+50% PSE treatments. Water activity was higher in the 100% PSE treatment than in other treatments. No differences in lactic acid bacterial counts among these treatments were observed. The pH values and water activity of the meat samples decreased, while lactic acid bacterial counts increased with storage time. TBA values among these treatments were not significantly different; however, the increase% of TBA values was higher for the 100% PSE treatment. TBA values of all treatments remained relatively low during storage. Chinese sausages made with 50–100% PSE pork had lower sensory texture, flavor and overall acceptability scores than the control samples, but were of acceptable quality.     

High-pressure-cooked Low-fat Pork and Chicken Batters as Affected by Salt Levels and Cooking Temperature

The application of high pressure (200 and 400 MPa, 30 min) favored water and fat binding properties of chicken and pork batters even at low ionic strength. Textural properties of meat batters (particularly hardness and chewiness, and to a lesser extent springiness and cohesiveness) were influenced by cooking temperature. High pressures influenced the texture of batters, so that pressurized samples were less hard, cohesive, springy or chewy than nonpressurized samples; this effect was not related to on salt concentration. High pressure treatment limited the formation of gel structures, which probably was associated with its preserving effect against thermal denaturation of meat proteins.     

Comparison of Essential Metals in Different Pork Meat Cuts from the Serbian Market

Pork consumption in Serbia accounts for a large share of total meat consumption. Pork is valuable sources of nutrients. We analyzed metal content in three different cuts of pork collected from the Serbian market during 2014. Analyses of the following isotopes: zinc (⁶⁶Zn), copper (⁶³Cu) and iron (⁵⁷Fe) were performed by ICP-MS. Our data show that Zn, Cu and Fe were present in significantly different levels in hind leg, loin and shoulder, and that shoulder meat was richest in the analyzed metals. The differing mineral status of different pork cuts implies differences in their nutritional benefits for the human diet.     

魔芋葡甘聚糖基活性纳米复合膜的构建及性能研究

目的 对魔芋葡甘聚糖(konjac glucomannan, KGM)薄膜进行改良。方法 以KGM为基质, 棉花纤维素纳米晶须(cellulose nanocrystals, CNC)作为增强剂, 马尾藻多酚(phlorotannins from Sargassum, PS)为抗菌抗氧化剂, 通过物理性能、自由基清除能力和抗菌性检测, 筛选KGM/CNC/PS活性纳米复合膜包装材料。该包装材料运用在鲜猪肉保鲜上时, 以菌落总数(total bacterial count, TBC)、总挥发性盐基氮(total volatile base nitrogen, TVB-N)、硫代巴比妥酸反应物(thiobarbituric acid reactive substances, TBARS)、pH等指标判断鲜猪肉腐败变质程度。结果 当质量比KGM:CNC:PS=100:9:9.81 (KCP-9)时, KGM/CNC/PS活性纳米复合膜的热稳定性、力学性能、水蒸气阻隔性能相对其他比例的复合膜显著提高, KGM:CNC:PS=100:9:18.53 (KCP-17)时, 抗氧化和抗菌性能最佳, 后者运用在鲜猪肉上时, TBC、TVB-N、TBARS、pH等指标明显优于对照组中不使用任何保鲜剂的猪肉, 可延缓鲜猪肉腐败变质速度, 延长其货架期。结论 当KGM:CNC:PS=100:9:18.53 (KCP-17)时, KGM/CNC/PS活性纳米复合膜包装材料具有良好的抗氧化和抗菌性, 在食品保鲜领域具有潜在的应用前景, 本研究可为提高食品包装材料机械性能、抗菌性和抗氧化能力研究提供参考。     

几种保湿剂对宁乡花猪肉干食用品质的影响

主要采用感官检验及测定水分含量的方法,分别研究了山梨醇、甘油、甘露醇、多聚磷酸钠等4种保湿剂对宁乡花猪肉干食用品质的影响。结果表明,这4种保湿剂对猪肉干食用品质具有明显改善作用。最合适的添加量分别为:山梨醇4g/100g、甘油3m L/100g、甘露醇4g/100g、多聚磷酸钠0.2g/100g。其中甘油的效果最好,在其最适添加量为3m L/100g时,肉干感官评分为92,水分含量为45.1%,空白对照肉干样品感官检验评分为65,水分含量为31.5%。