高压和食盐对鸡肉肠品质特性的影响

在不同压强条件（0.1、200、400 MPa）下对不同食盐添加量（质量分数0%、1%、2%）的生鸡肉肠加热（60 ℃）处理30 min,测定处理后鸡肉肠的持水力、水分分布、质构特性和微观结构,分析高压和食盐对鸡肉肠热诱导凝胶特性的影响。结果发现：常压下,减少食盐添加量会降低鸡肉肠的保水性和质构特性,但高压处理能降低食盐对鸡肉肠的影响。相比常压组,200 MPa高压处理能显著提高产品的保水性和质构特性（P＜0.05）,而400 MPa的高压处理则显著降低产品的保水性和质构特性（P＜0.05）。高压能促进肉糜中的肌纤维分解,使不易流动水的比例升高,自由水比例下降;200 MPa下能形成致密的凝胶网络,而400 MPa则阻碍凝胶网络的形成。高压结合加热处理可用于提高低盐鸡肉肠的品质特性。     

Combination of high pressure and heat on the gelation of chicken myofibrillar proteins

The effects of combinations of high pressure and heat on chicken myofibrillar gels were investigated. High pressure was either applied simultaneously with heating (heating under pressure, HUP), before heating (PBH) or no high pressure with heat-only (HT). PBH treatment induced many similar properties in gels as did by HT treatment, except that PBH treatment promoted secondary structure transformation and formed more covalent bonds. HUP treatment resulted in less heat denaturation of the protein, induced fewer hydrophobic interactions and covalent bonds, hindered secondary and tertiary structural transformation, and formed a gel with a more porous microstructure. The gels induced by HUP treatment had softer texture and higher water holding capacity than gels induced by PBH or HT treatments. These findings suggest that high pressure with HUP treatment changes gel properties by resisting the heat-induced denaturation and gelation of myofibrillar proteins, while high pressure with PBH treatment alters gel properties by promoting denaturation of myofibrillar proteins.Industrial relevanceThe main constituents in meat are myofibrillar proteins, which are responsible for the functional properties of processed meat products. The gelation of myofibrillar proteins differs according to the sequence in which pressure/temperature combinations are applied. The pressure-modified protein interactions should be considered when adopting high pressure in meat product processing since the microstructure of the meat gel is affected by pressure, which would further affect water holding capacity and textural properties. HUP treatment showed its advantages in forming a fine microstructure and improving water-holding capacity.     

Simultaneous application of microbial transglutaminase and high hydrostatic pressure to improve heat induced gelation of pork plasma

The effects of treating porcine plasma with microbial tranglutaminase (MTGase) under high hydrostatic pressure (HHP) were studied as a means of improving its gel-forming properties when subsequently heated at pH 5.5, near the pH of meats. Plasma containing varying levels of commercial MTGase was pressurized (400MPa, room temperature, pH 7) for different times, and adjusted to pH 5.5 prior to heating to induce gelation. MTGase-treatment under HHP led to greater enhancement of heat-induced plasma gel properties as compared to control samples. The greatest improvements were achieved by pressurising plasma with 43.3U MTGase/g protein for 30min, thereby achieving recoveries of 49% and 63% in fracture force (gel strength) and fracture distance (gel deformability) of the subsequently heat-induced gels, respectively, relative to gel properties obtained by heating untreated plasma at physiological conditions (pH 7.5).     

高压预处理及加热方式对混合蛋白凝胶特性的影响

将鸡肉肌原纤维蛋白(MPI)和大豆分离蛋白(SPI)按体积比1∶1混合,经过100、200、400、600MPa高压预处理20min,在40、55、70、85℃水浴加热20min制成凝胶,研究了凝胶的质构特性、保水性及微观结构。结果表明,55℃加热制备的凝胶明显优于传统线性升温制备的凝胶,硬度、弹性、保水性分别提高了35.50%、27.71%、47.29%。微观观察发现,混合蛋白高压处理后,形成的凝胶结构均匀致密,然而过高的压力预处理对混合蛋白凝胶会产生破坏作用。     

Protein extractability and thermal gel formability of myofibrils isolated from skeletal and cardiac muscles at different post-mortem periods

The effects of the post-mortem ageing period on the extractability of myofibrillar proteins from pork cardiac and rabbit skeletal muscles under various conditions of pH and ionic strength were studied with particular reference to the changes in the solubility of individual myofibrillar proteins and their denaturation characteristics. The ultimate influence of these changes on the heat-induced gel forming ability of myofibrils isolated from cardiac and skeletal muscles at different post-mortem stages was also investigated. Results showed that pork cardiac myofibrils always exhibited lower solubility than those from rabbit skeletal muscles under identical conditions of pH, ionic strength and temperature. SDS-PAGE profiles indicated several quantitative differences in the relative proportion of individual protein species present in cardiac and skeletal myofibrils. The solubility of various proteins present in myofibrils was also affected differently on heating in 0-1 and 0-6 _M NaCl solution at various pH values. Thermal denaturation of cardiac myofibrils occurred at about 10°C higher than that of skeletal myofibrils as revealed by differential scanning calorimetry. Cardiac myofibrils formed much weaker heat-induced gels than those produced by skeletal myofibrils under identical conditions of temperature, pH, ionic strength and protein content.     

Thermal Gelation of Myofibrils from Pork, Beef, Fish, Chicken and Turkey

Myofibril gels with 5, 7, or 10% protein and 2% NaCl were prepared from pork, beef, fish, chicken and turkey muscles using a heating rate of 0.7°C/min and pH 6.0 to compare the thermal gelation properties of myofibrillar protein from different species. The force required to rupture gel (Pf), force required to move plunger through gel (Fp), viscosity index (Ni), and elasticity (Ea) increased and cooking loss decreased with increasing protein contents. Myofibrils of chicken breast and thigh had lower and fish and turkey thigh had higher cooking loss at protein contents of 7% or 10%.     

超高压对鸡肉肌原纤维蛋白-MgCl2凝胶特性的影响

在低盐条件下（2.3% NaCl）,以含有质量分数0.3% MgCl2的鸡肉肌原纤维蛋白（myofibrillar protein, MP）混合体系（MP-MgCl2）为研究对象,室温下（20～25 ℃）考察超高压处理（high pressure processing, HPP）（100～400 MPa,10 min）对混合体系凝胶硬度和保水性（water holding capacity,WHC）的影响, 并通过对该混合体系流变特性、横向弛豫时间及凝胶微结构分析,探讨其凝胶特性的变化机制。结果表明： 100～400 MPa的HPP可显著提高凝胶的硬度和WHC（P＜0.05）,且300 MPa是改善其凝胶硬度的合适压力;HPP 通过增加MP-MgCl2混合体系的储能模量（G’）,缩短自旋-自旋弛豫时间T22和T23,促进凝胶形成交联、密实的多孔 网络结构,进而改善混合体系凝胶的特性。     

基于宰后蛋白质磷酸化研究L-组氨酸和L-赖氨酸对鸡胸肉加工特性的影响

为研究低盐（1% NaCl）条件下添加L-组氨酸（L-histidine，L-His）及L-赖氨酸（L-lysine，L-Lys）调节宰后鸡胸肉肌原纤维蛋白磷酸化的变化规律及其对鸡胸肉加工特性（蒸煮损失、质构、蛋白溶解度、流变特性）的影响，提取腌制后鸡胸肉肌原纤维蛋白，进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳，再通过荧光染色和液相色谱-串联质谱鉴定。结果表明：L-His和L-Lys的添加不影响肌原纤维蛋白的整体磷酸化水平，但是可以改变单个蛋白质的磷酸化水平；相比于1% NaCl处理组，1% NaCl＋0.06% L-His/L-Lys处理组硬度和蛋白溶解度均有显著提高，蛋白流变特性改善，蒸煮损失无显著变化；相关性分析得出，多个蛋白质磷酸化水平与肉的蒸煮损失及蛋白溶解度等加工特性呈显著正相关或负相关，且单个蛋白质的磷酸化水平还会受到其他蛋白质磷酸化水平的影响；将11 条磷酸化水平差异显著的条带进行质谱鉴定后，发现大多是与肌肉收缩或糖酵解有关的酶，表明L-His、L-Lys的添加可能通过对肌原纤维蛋白磷酸化水平产生正面效应影响宰后僵直成熟过程，进而影响肉品品质。     

超高压对带鱼鱼糜凝胶特性及其肌原纤维蛋白结构的影响

以带鱼鱼糜为原料,分别采用不同的超高压参数和热处理,分析鱼糜凝胶强度、白度、质构指标、微观结构以及肌原纤维蛋白含量和构象单元的变化,探究超高压处理对带鱼鱼糜凝胶特性及其肌原纤维蛋白结构的影响。结果表明：超高压诱导带鱼鱼糜凝胶网络结构形成,超高压诱导组质构特性、凝胶强度、白度均比对照组有所提高,扫描电子显微镜图显示350 MPa保压8 min后（350-8组）所形成的鱼糜凝胶网络结构与热诱导组接近;超高压处理后,鱼糜凝胶中的肌原纤维蛋白含量有所降低,经圆二色光谱测定,肌原纤维蛋白的两个负峰逐渐消失,其α-螺旋结构相对含量下降,无规卷曲和β-折叠的相对含量有不同程度上升,350-8组无规卷曲相对含量与热诱导组接近。综上,适宜的超高压处理条件（350 MPa保压8 min）显著影响带鱼鱼糜凝胶特性及其肌原纤维蛋白二级结构,促进凝胶网络形成,改善鱼糜凝胶品质。     

Gelation properties of chicken myofibrillar protein induced by transglutaminase crosslinking

Gelation properties of chicken myofibrillar protein isolate (MPI) and the effect of microbial transglutaminase (MTG) were studied using a dynamic oscillatory rheometer and a texture analyzer. Final heating temperature had a great impact on gel stiffness and the maximum gel stiffness was obtained at 95 °C. pH and ionic strength also influenced gel stiffness and the maximum gel stiffness was achieved at pH 6, 0.9 M NaCl; however, less stiff gels were formed in 0.6 and 1.2 M NaCl. In the MPI concentration range of ∼0.5-5%, a positive correlation was observed between gel stiffness or gel peak force and MPI concentration. When MTG was included at levels of ∼0 to 12-15 U, positive linear relations were found between gel stiffness or peak force and MTG levels. However, negative correlations for these parameters were observed at higher MTG concentrations. When MTG level was greater than 15 U, gel stiffness or peak force tended to decrease. The improvement in gel strength or gel peak force for the MPI with inclusion of MTG suggested that some ε (γ-glutamyl) lysine (G-L) crosslinking occurred among myofibrillar molecules. Thus, MTG is useful in improving gelation properties of heat-induced MPI gel and provides new opportunities to expand the utilization of low value meat in muscle foods.     

超高压诱导鱼糜凝胶性能的研究

本文研究了压力对六齿金线鱼鱼糜凝胶的凝胶特性、溶解度、电泳和TCA-可溶性肽含量的影响,并与热处理的结果对比。研究表明,压力诱导凝胶的凝胶强度随压力增大而增大,600MPa处理的凝胶强度达到最大值为429．775g-cm,比热处理凝胶高23．03％。与热处理样相比,压力诱导凝胶的硬度、咀嚼性较低,内聚性较高,弹性在200MPa以上时较高,持水性较好,白度较低。压力诱导凝胶的溶解度高于热处理凝胶,SDS-PAGE显示其肌球蛋白重链较深,表明压力会使内源性转谷氨酰胺酶的活性降低,不利于形成ε-（γ一谷氨酰）赖氨酸键。压力诱导凝胶的TCA-可溶性肽含量低于热处理凝胶,表明压力可抑制引起鱼糜凝胶劣化的内源性水解蛋白酶的活性。结果表明,超高压处理有利于形成柔软、有弹性和凝胶强度高的凝胶;对内源性水解蛋白酶活性的抑制作用可能是超高压改善其凝胺特性的主要原因之一。     

Cold storage of porcine plasma treated with microbial transglutaminase under high pressure. Effects on its heat-induced gel properties

The objective of this work was to study the heat-induced gelling properties, at acid pH, of porcine plasma previously treated with microbial transglutaminase (MTGase) under high pressure (HP), when kept under refrigeration conditions for different times (setting time). The results indicated that, although the cross-linking activity of MTGase was enhanced under pressure, consequently, improving the thermal gel texture, the most significant effects, particularly on gel hardness, were obtained by keeping the treated plasma solutions under refrigeration for at least 2 h before gelation. On the whole, under such conditions, increases of approximately 60% of this textural parameter, calculated on the basis of the values corresponding to the heat-induced non-treated plasma gels at pH 5.5, were achieved. However, from the SDS–PAGE profiles, it can be suggested that mechanisms other than polymerisation by MTGase explain the beneficial effects of the treated plasma cold storage on gel texture. In contrast, the setting time had no effects on the water-holding capacity of heat-induced plasma gels at acid pH value, although this gel property was slightly enhanced by submitting porcine plasma solutions to the combined treatment (MTGase plus HP), with improvements being in accordance with the better-structured network of these heat-induced plasma gels.     

超高压条件下亚麻籽胶对猪肉肌原纤维蛋白凝胶特性的影响

将亚麻籽胶添加到猪肉肌原纤维蛋白中制成混合体系,经不同压力梯度（0.1～400 MPa、10 min）处理,通过对混合体系的流变特性、低场核磁水分分布、分子间作用力和凝胶微观结构分析,研究不同压力下亚麻籽胶对肌原纤维蛋白凝胶保水性（water-holding capacity,WHC）、硬度以及作用机制的影响,确定最适处理压力,以期进一步增强亚麻籽胶对肌原纤维蛋白凝胶特性的改善作用。结果表明：0.1～100 MPa处理时,亚麻籽胶显著提高了肌原纤维蛋白凝胶WHC,使肌原纤维蛋白储能模量（G’）、损耗模量（G’’）下降,显著降低了肌原纤维蛋白凝胶强度（P＜0.05）;压力升高至200 MPa时,亚麻籽胶进一步提高了肌原纤维蛋白凝胶WHC,增加了其G’、G’’和结合水的峰面积,形成的凝胶微观结构交联致密,显著提高了肌原纤维蛋白凝胶硬度（P＜0.05）;300～400 MPa处理时,随着压力进一步增加,亚麻籽胶对肌原纤维蛋白凝胶WHC和凝胶强度的提高作用下降。0.1～400 MPa时,随着压力增加,对照组与处理组疏水性和活性巯基含量均显著增加（P＜0.05）,亚麻籽胶对其基本无影响。以上结果表明,200 MPa处理条件下,亚麻籽胶对肌原纤维蛋白凝胶特性的改善达到最佳,是亚麻籽胶发挥其作用的最适处理压力。     

High pressure–temperature degradation kinetics of polyacetylenes in carrots

The present study assessed the effect of high pressure–temperature (HPT) processing on the levels of three polyacetylenes in carrot disks immediately after processing in comparison to sous-vide processing. The degradation kinetics of these compounds following processing at HPT was also investigated. The highest pressure–temperature combination which gave maximum retention during the time 10–30 min, for falcarinol it was 400 MPa, at 50 and 60 °C for 10 min; for falcarindiol it was 400 MPa, at 50 °C for 10 min and for falcarindiol-3-acetate was 400 MPa, at 50 °C for 10 min, respectively. Falcarindiol-3-acetate was found to be most barosensitive and falcarindiol was found to be most thermosensitive of the three polyacetylenes studied. When compared with sous-vide (SV) processed carrot disks, HPT processed samples showed higher retention of polyacetylenes. The changes in the levels of polyacetylenes during HPT treatment were adequately described by Weibull model function.     

超声波辅助酸/碱溶解等电点沉淀法提取鸡架分离蛋白的组成及其凝胶特性

利用高强度超声（high intensity ultrasound,HIU）辅助酸/碱溶解等电点沉淀（isoelectric solubilization/precipitation,ISP）法提取鸡架分离蛋白（protein isolate,PI）,采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳研究PI组成,并分析PI凝胶特性。结果表明：PI主要由肌原纤维蛋白组成;酸溶解会导致肌球蛋白重链降解,HIU可减弱降解程度;碱溶PI凝胶的硬度、蒸煮损失率、离心损失率与对照（鸡胸肉糜凝胶,后同）无显著差异,显著高于酸溶PI凝胶（P＜0.05）;HIU显著提高了酸溶PI凝胶的硬度和弹性（P＜0.05）,降低了蒸煮损失率及离心损失率（P＜0.05）;PI凝胶白度均显著低于对照（P＜0.05）。碱溶PI凝胶对水分子的结合力和束缚力均优于酸溶PI凝胶;碱溶PI凝胶与对照凝胶均具有均匀致密微观结构,而酸溶PI凝胶微观结构明显粗糙、不均匀。结论：HIU辅助碱溶ISP法可高效提取鸡架中肌原纤维蛋白并保持其凝胶特性,有助于鸡架增值利用。     

Gelation of chicken batters during heating under high pressure

The gelling process of chicken meat batters, which were heated (75 °C) under atmospheric pressure or high pressure (200/400 MPa), was investigated by determining the hardness of batter, residual denaturation enthalpy, microstructure, and protein secondary structure. The results showed that meat batters heated at 200 MPa showed a similar increase in hardness to heat-only samples, but meat batters heated at 400 MPa showed a texture decreasing tendency after a limited increase. High pressure disrupted the myofibrils, promoted protein denaturation and aggregation in the first stage of heating under pressure treatment. In the second stage of treatment, heating was the main driving force for protein gelation, which was disturbed by hindering the structural transformation of proteins in the presence of high pressure during heating. The effect of 200 MPa on muscle proteins was relatively gentle and had a less negative effect. Excessive high pressure should be avoided when applying heating under pressure for gel-type meat products processing.Industry relevanceHigh-pressure processing is increasingly applied in the meat industry. By combining high pressure with heating, their effects on texture improvement and microbial inactivation can be maximized. In this study, the influence of high pressure on the texture of meat products was analyzed, which showed that excessive pressure would significantly interfere with the thermal denaturation of the protein, thus adversely affecting the formation of the gel structure. High pressure at 400 MPa and above should be avoided when applying heating under pressure for gel-type meat products processing.     

3种不同香辛料提取物对猪肉肌原纤维蛋白功能特性的影响

将迷迭香、丁香、肉桂3种香辛料提取物添加到猪肉肌原纤维蛋白中(0.005、0.010、0.020 g/g pro),研究其对蛋白质巯基、表面疏水性、溶解度及凝胶特性的影响。结果表明,3种香辛料提取物均降低了蛋白质的总巯基含量和溶解性,表面疏水性随添加量的增加先升高后降低。3个添加量在加热最终阶段弹性模量(G’)均高于对照组,低、中添加量提取物使凝胶强度增加,有利于蛋白凝胶的形成,而高添加量提取物对凝胶形成有破坏作用。因此,香辛料提取物与肌原纤维蛋白发生相互作用,从而对蛋白质的结构和凝胶特性产生影响。     

转谷氨酰胺酶对猪肉肌原纤维蛋白凝胶性质的影响

以猪背最长肌为材料,研究转谷氨酰胺酶(TG)浓度对肌原纤维蛋白质(MP)热诱导凝胶强度和持水力的影响,探讨转谷氨酰胺酶在不同pH 值条件下对肌原纤维蛋白质凝聚性和交联的作用以及对热诱导凝胶强度、持水力的影响,比较TG 处理对凝胶结构的微观影响。结果表明：TG 处理会显著提高肌原纤维蛋白质的凝胶强度,TG最佳使用量为0.3%,NaCl 浓度为0.6mol/L,pH 值在5.8～6.4 之间时添加TG 会增加蛋白质的蒸煮损失,而pH 值在6.4～6.7 范围内添加TG 可降低蒸煮损失;电镜扫描结果表明TG 处理可改善热诱导凝胶的网络结构;TG 处理可改善肌原纤维蛋白的质构性质。     

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.     

Coagulation of Egg White of Soft-Shell Turtle (Pelodiscus Sinensis) at High Pressure or High Temperature

The coagulations of soft-shell turtle egg white at high pressure or at high temperature were investigated and compared to chicken egg white. Unlike chicken egg white, no coagulation of soft-shell turtle egg white was observed after high-pressure processing (HPP; 200–600 MPa) or heating treatment (75°C). Basic amino acids, histidine, lysine, and arginine were present at higher percentages in soft-shell turtle egg white proteins than in chicken egg white proteins. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis showed that the intensities of soft-shell turtle egg white components were balanced, there were more components with high molecular mass in soft-shell turtle egg white, and that aggregates formed in both soft-shell turtle egg white and chicken egg white. This work revealed some differences in soft-shell turtle egg white compositions. The low protein content in egg white was responsible for the non-coagulation of soft-shell turtle egg white in response to high pressure or temperature.