Porcine Plasma Proteins as a Surimi Protease Inhibitor: Effects on Actomyosin Gelation

Effect of porcine plasma proteins (PPP) on thermal gelation of actomyosin in the presence and absence of fish proteinase was studied using a dynamic rheological test. Substantial decreases in development rate and magnitude of gel modulus were observed by the addition of proteinase to actomyosin gels. PPP was effective in protecting a myosin-heavy chain from proteolytic degradation, however, PPP itself interfered with the formation of actomyosin gel. Lower gel modulus was observed with actomyosin gels developed with higher concentrations of PPP added. Overall, PPP reversed the loss of gel modulus by the proteinase, however, the recovered gel modulus was only as high as those containing PPP only. These results implicated that, although PPP may revert autolytic activity in surimi, it interfaces with actomyosin gelation.     

Gelation Characteristics of Paddlefish (Polyodon spathula) Surimi Under Different Heating Conditions

Gelation properties of paddlefish surimi were investigated with different heating procedures. Without pre-incubation, gel strength of paddlefish surimi increased as temperature increased from 40 to 60 °C. Pre-incubation at 40 °C caused myosin degradation and reduced gel strength by 55% compared to the control. Pre-incubation at 70 °C followed by cooking at 90 °C produced gels with maximum strength. Isothermal heating between 40 and 50 °C produced rheological transitions between 0 and 15 min. Beef plasma powder reduced myosin degradation and enhanced gelation of surimi incubated around 40 °C. These results indicated that the gel-weakening phenomenon in paddlefish surimi was due to the degradation of myosin by some endogenous protease(s).     

Influence of Some Protease Inhibitors on Gelation of Squid Muscle

ABSTRACT: The effect of 4 food-grade protease inhibitors–bovine plasma, potato powder, ethylenediamine-tetraacetic acid, and sodium pyrophosphate–on heat gelation of squid (Todaropsis eblanae) muscle was studied. The action of these ingredients was characterized by determining the proteolytic activity in batters containing them and the rheological properties of gels made with them. The gelation profile showed that the setting effect was greatest with pyrophosphate (PPI) and that gel rigidity was highest with bovine plasma (BP). All 4 inhibited proteolytic activity to some extent at 65 °C. BP was the most effective. At 40 °C, only EDTA and PPI were active. Rheologically, the most effective combination was PPI plus bovine plasma in that this combined inhibition of proteolytic activity with gel enhancement.     

Protease Inhibitors Affect Physical Properties of Arrowtooth Flounder and Walleye Pollock Surimi

The effects of protease inhibitors from potato, bovine plasma and egg white on the punch, torsion and color tests of arrowtooth flounder and pollock surimi were determined. At 2% addition, the inhibitors increased the strength of arrowtooth gels while variable results were found with pollock gels. Bovine plasma produced a gel with a yellow hue while the gel with potato inhibitor was darkest.     

Gel Forming Characteristics of Frozen Surimi from Chum Salmon in the Presence of Protease Inhibitors

When salted surimi paste of chum salmon was incubated at 20–60°C, a marked loss of the breaking strength of heat-induced gel occurred simultaneously with breakdown of myosin heavy chain, but this was effectively suppressed by addition of cysteine protease inhibitors or bovine plasma powder. In the presence of protease inhibitor, the surimi gels were formed at relatively low temperatures showing highest gel strength at incubations of 50 and 60°C. Chum salmon surimi showed no evidence of suwari and no myosin heavy chain cross-linking.     

鲟鱼鱼糜凝胶形成过程中的物理化学变化

以鲟鱼为原料制备鲟鱼鱼糜凝胶,通过蛋白质组成、水分分布、傅里叶变换红外光谱、流变特性分析以及十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析研究了鲟鱼鱼糜凝胶形成过程中的物理化学变化。结果表明：在鲟鱼鱼糜凝胶形成过程中,其盐溶性蛋白比例和水溶性蛋白比例均下降,不溶性蛋白比例上升;肌球蛋白重链、肌动蛋白含量均下降;鱼糜蛋白质的吸收峰在1 100 cm－1附近发生红移;鲟鱼鱼糜的弛豫时间T2有4 个区间,加工后鱼糜凝胶对水分子的束缚力更大,黏弹性也更高;说明经过漂洗、擂溃和凝胶化处理后,鲟鱼鱼糜凝胶形成了致密的凝胶网状结构。本研究为进一步提高鲟鱼鱼糜凝胶的品质提供了理论依据。     

鲢鱼卵中低分子CPIs的纯化鉴定及改善鱼糜凝胶强度的效果研究

通过比较鲢鱼卵半胱氨酸蛋白酶抑制因子（cysteine proteinase inhibitors,CPIs）粗提过程中的比活力（Azocasein法）,确定其最佳粗提条件为：以含0.1 mmol/L苯甲基磺酰氟（phenylmethanesulfonyl fluoride,PMSF）的20 mmol/L磷酸盐缓冲液（pH 6.0）作为匀浆缓冲液,并于30 ℃对匀浆样进行pH 3.0酸处理10 min,然后碱回调至pH 8.0,CPIs纯度提高了15.54 倍。进一步经SP Sepharose Fast Flow阳离子层析验证表明,与pH 4.0相比,pH 3.0酸处理能高效除去活性峰Ⅱ中的酸碱及热不稳定杂蛋白,使CPIs比活力提高了48.22 倍。采用SephacrylS-200分子筛层析,获得部分纯化的低分子CPIs组分Ⅱ-b和Ⅱ-c,比活力和纯化倍数分别为1 098.59 U/mg、312.10 倍和1 769.23 U/mg、502.62 倍。电泳分析表明,明胶底物-SDS-反相酶谱法无法鉴定Ⅱ-b和Ⅱ-c的抑制活性;而与木瓜蛋白酶在适宜条件下反应后进行的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecylsulfatepolyacrylamide gel electrophoresis,SDS-PAGE）则初步鉴定Ⅱ-b和Ⅱ-c中均含有至少7 kD和10 kD两种低分子CPIs。最后经质构分析表明,Ⅱ-b和Ⅱ-c以5 U/g添加入鲢鱼鱼糜时,均能够极显著提高鲢鱼鱼糜凝胶强度（48.77%和55.55%）,抑制软化。     

Gelation of Beef Heart Surimi as Affected by Antioxidants

Oxidation of proteins (carbonyls) and lipids (TBARS) in beef heart surimi-like materials during preparation and storage (2°C) was inhibited by propyl gallate (0.02%) or α-tocopherol (0.2%). Inhibition of oxidation did not affect surimi gel property (storage modulus, G'). Storage promoted oxidation of proteins in 0.2% ascorbate-washed mince, leading to increases in peak (～ 55°C) and final (70°C) G' of thermally induced surimi gel. Protein carbonyls in stored surimi and its sol (salted), as well as TBARS of the sol, strongly correlated with both peak and final G of gels. Incorporation of tripolyphosphate into washed mince promoted gelation whether the surimi-like material was oxidized or not.     

Inhibition of Thermal Degradation of Mackerel Surimi by Pig Plasma Protein and L-kininogen

ABSTRACT: Use of purified L-kininogen to prevent actomyosin (AM) degradation by cathepsins, and pig plasma proteins to reduce mackerel modori were investigated. Myosin heavy chain (MHC) degradation in AM containing various cathepsins was significantly inhibited by purified L-kininogen. The texture of mackerel gel increased to 2-fold and 1.7-fold in breaking force (g) and deformation (cm) separately after adding 1% pig plasma protein. SDSPAGE showed that degradation of MHC in mackerel surimi was significantly reduced after 1% pig plasma protein addition at several temperatures. It suggested that the pig plasma protein containing L-kininogen could effectively reduce the modori phenomenon of mackerel surimi during processing.     

Heat-Induced Gelation Properties of Surimi From Mechanically Separated Chicken

Chicken surimi was prepared from fresh mechanically separated chicken meat using a sodium bicarbonate washing process. The heat-induced gelation properties were assessed under different conditions of pH, temperature, heating rate, protein and sodium tripolyphosphate (TPP) concentrations. Surimi gel strength increased (p < 0.05) after: reducing pH from 6.4 to 6.0, increasing temperature from 40°C to 80°C, reducing heating rate from 5°C/min to 1°C/min, increasing protein concentration from 4% (w/w) to 8% (w/w) or addition of 0.3% (w/w) TPP. Freeze thaw stability studies revealed that the gel strength of surimi decreased (p < 0.05) when subjected to frozen storage at – 18°C.     

Linear Heating Rate Affects Gelation of Alaska Pollock and Pacific Whiting Surimi

Shear stress of Alaska pollock surimi gels with and without beef plasma protein (BPP) increased as heating rate decreased, but shear strain was unaffected. An increase in shear stress was accompanied by an increase of cross-linked myosin heavy chain. Slow heating rates increased proteolysis in Pacific whiting surimi as shown by degradation of myosin heavy chain and low shear stress and shear strain. Proteolysis of whiting surimi was lessened by BPP to a greater extent at rapid heating rates (20 and 30°C/min) than at slow heating rates (1 and 5°C/min).     

钙离子对白鲢鱼糜热诱导凝胶化的影响

本文通过不同浓度钙离子对白鲢鱼糜凝胶的凝胶特性、溶解率及MHC影响的研究,探讨了Ca2+增强白鲢鱼糜凝胶特性的机理及在白鲢鱼糜中的适宜添加量。结果表明,低浓度的钙离子(10、20mmol/kg)可以激活内源性转谷氨酰胺酶,催化MHC之间共价交联形成ε-(γ-Glu)-Lys共价键,导致鱼糜凝胶溶解率降低,MHC减少,凝胶特性增强,且钙离子的最适添加量为20mmol/kg;但是50mmol/kg的钙离子浓度使MHC的交联受阻,致使鱼糜凝胶特性降低,溶解率增加;当钙离子浓度达到80mmol/kg时,钙离子可与鱼糜蛋白之间形成蛋白质-钙-蛋白质的钙桥结构,使凝胶变硬,弹性降低。     

Combination Effects of Microbial Transglutaminase, Reducing Agent, and Protease Inhibitor on the Quality of Hairtail Surimi

A combination of microbial transglutaminase (MTGase), reducing agent and protease inhibitor was employed to improve the quality of underutilized fish surimi. SDS-PAGE indicated that cross-linking of myosin heavy chain (MHC) occurred in MTGase-contained samples, while MHC of samples without MTGase disappeared after 120 min incubation at 45°C. Although the gel-forming ability increased with MTGase added up to 0.6 unit/g, it was still too low to be commercially acceptable. However, the combined use of 0.1% NaHSO₃, 0.01 mM transepoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64) and 0.35 units MTGase/g substantially improved the quality of hairtail surimi. Based on this result, the combined use of E-64, MTGase and NaHSO₃ seemed to be a better way to improve gel-forming ability of hairtail surimi.     

白鲢鱼鱼糜凝胶过程中水分及凝胶特性的变化

本文研究了白鲢鱼鱼糜凝胶过程中的水分及凝胶特性变化规律,主要考察了鱼糜在凝胶过程中持水力、低场核磁T2横向弛豫时间及T2峰比例、凝胶特性、色差及凝胶微观结构指标的变化,并通过TG-DTGA(Thermogravimetric-Derivative Thermogravimetry Analysis)分析鱼糜凝胶在两段式加热中的结晶水含量变化。鱼糜与淀粉、水、盐混合斩拌后,采用两段式凝胶进行凝胶化。结果发现,加热过程中鱼糜持水力显著增加,在第二段加热25 min时达到最大值为96.93%;T23弛豫时间呈现下降的趋势,并在第二段加热过程中下降速度较快,在第二段加热30 min时达到最低值为30.51 ms;T23峰比例呈现上升趋势且在第一段加热过程中升速较快,在第二段加热10 min后达到最大值为93.97%;弹性、硬度等显著增加;亮度和白度呈现显著上升的趋势;结晶水含量在二段加热中呈现先增加后减少的趋势,在第一段加热30 min时达到最大值为6.59%。     

Protease Inhibitor Effects on Torsion Measurements and Autolysis of Pacific Whiting Surimi

Beef plasma protein (BPP), egg white and potato extract were tested for their ability to inhibit proteolysis in fish mince and surimi made from Pacific whiting (Merluccius productus). Strong inhibition resulted from all three compounds in fish mince when measured by autolysis. However, when tested in surimi significant differences occurred among the compounds. BPP showed strongest inhibition of proteolytic effect followed by egg white and potato extract when measured by autolysis, gel electrophoresis and torsion. BPP was an effective inhibitor in surimi at a concentration as low as 1%.     

有机酸诱导和热诱导形成的秘鲁鱿鱼香肠的品质比较

基于传统加工方式制成的头足类鱼糜制品的凝胶强度普遍较差。酸诱导凝胶是除热诱导凝胶外的另一种理想的凝胶方法。本研究采用柠檬酸钠、琥珀酸钠、乳酸钠和醋酸钠4 种有机酸盐代替氯化钠对秘鲁鱿鱼鱼糜中的盐溶性蛋白进行溶出,之后进行热诱导和对应有机酸诱导,对形成的鱼肉香肠品质进行了比较。结果发现：有机酸诱导组在破断强度、持水性、硬度、回复性以及咀嚼度方面比热诱导组形成的样品显著提高（P＜0.05）;在白度上甚至超过了自身以及部分海水鱼、淡水鱼的热诱导鱼糜制品;在破断距离、弹性和黏聚性等指标上两种凝胶方式差异不显著（P＞0.05）。琥珀酸钠组用两种诱导方式制成的鱼糜制品在感官上均较好,而乳酸钠组较差。     

羊血浆蛋白对高温杀菌鱼糜制品凝胶特性的影响

为改善高温杀菌鱼糜制品的品质,研究羊血浆蛋白对121℃处理鱼糜制品凝胶特性的影响。以白鲢鱼糜为原料,测定羊血浆蛋白的添加对鱼糜凝胶质构特性、凝胶强度、持水性、折叠性、白度和流变特性的影响,并通过测定分子间作用力和溶解率的变化探究其影响机制。结果表明,与对照组相比,随着羊血浆蛋白的添加,高温处理鱼糜制品的硬度、弹性、胶粘性和咀嚼性显著增大(P<0.05),持水性显著增强(P<0.05),折叠性能增强,白度降低。当添加量为2%时,鱼糜制品的凝胶强度增加了92.88%。分子间作用力和溶解率分析显示,添加羊血浆蛋白能够提高体系氢键和非二硫共价键含量,从而改善高温处理鱼糜制品凝胶品质。     

Thermal Gelation in Relation to Binding of Bovine Serum Albumin-Polysaccharide Systems

Thermal gelation of bovine serum albumin (BSA)-sodium alginate, BSA-pectin and BSA-methyl cellulose systems in relation to binding was studied using rheological testing, turbidimetric analysis and gel filtration. Two electrostatic binding mechanisms, distinguished by particle and chain segment binding models were found in BSA-anionic polysaccharide systems. Particle binding resulted in poor gelation properties. Positive effects on gelation were found when conditions favored the chain segment binding model. Mechanisms for gelation-binding relationships were hypothesized. No evidence of binding was found in the BSA-methyl cellulose system, which generally exhibited the combined gelation properties of the individual components.     

Substrate Profiling of Cysteine Protease from Zingiber officinale

Plants have different types of proteases and four types of cysteine protease have been isolated from ginger (GPI, II, 2, and 3). This study analyzed the structure and cleavage specificity of a newly isolated protease (GPii) from Zingiber officinale to evaluate the general properties of this protease. GPs were purified using anion exchange chromatography. Three GPs were purified and shown to be similar to the three reported types of GPs (GPII, 2, and 3). This is the first study in which one cultivar contains three types of GPs. GPii was sequenced, and revealed to carry two substitutions compared with GPII. The cleavage specificity of GPii was analyzed using protein substrates. GPii showed cleavage specificity for Ser, Gly, Lys, and Arg at first position; Ala, Pro, Ile, and Tyr at the second position; and Gly at the third position of the N-terminal side. Further, GPii could not cleave the insoluble substrate.