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.     

Microbial Transglutaminase and Recombinant Cystatin Effects on Improving the Quality of Mackerel Surimi

ABSTRACT: Effects of microbial transglutaminase (MTGase), recombinant cystatin, or their combination on the gel properties of mackerel surimi were investigated. The addition of MTGase caused the cross-linking of myosin heavy chain (MHC) and substantially increased the gel strength (from 536.6 to 2012.4 g × cm), while the recombinant cystatin could effectively prevent the MHC degradation and gel softening during the production of mackerel surimi-based products. Combined use of MTGase and recombinant cystatin revealed synergistic effectiveness on improving the quality of mackerel surimi (increased from 435 to 2438 g × cm, set at 45 °C for 20 min).     

Purified NADPH-Sulfite Reductase from Saccharomyces cerevisiae Effects on Quality of Ozonated Mackerel Surimi

The NADPH-sulfite reductase from Saccharomyces cerevisiae was purified to electrophoretic homogeneity by ammonium sulfate fractionation, DEAE Sephacel, Sephacryl S-300 and DEAE Sephadex A-50 chromatography. Optimal pH was 7.3 and temperature 25°C. It was inhibited by IAA, PCMPS, PMSF, NEM, PCMB, cyanide and most divalent metal ions. For the ozonated mackerel surimi ground with purified reductase, the reactive SH increased from 2.29∞10⁵ to 4.46∞10⁵mole/g and gel strength from 256.7 to 360.5g·cm. According to SDS-PAGE, the recovery of myosin heavy chain was observed on the ozonated mackerel surimi with addition of NADPH-sulfite reductase.     

臭氧水漂洗对鲅鱼鱼糜品质及肌原纤维蛋白氧化的影响

采用不同浓度(0、2、4、6、8、10 mg/L)臭氧水对鲅鱼鱼糜进行漂洗处理,探究其对鲅鱼鱼糜色泽和风味特征以及肌原纤维蛋白氧化效应的影响。结果显示,经臭氧水漂洗后的鲅鱼鱼糜白度值高于未经臭氧水处理的样品。该漂洗处理明显降低了与腥味相关的芳香族、氨类、短链烷烃、甲基化合物及有机硫化合物的电子鼻响应值;GC-MS结果进一步证明:与对照组(0 mg/L臭氧水漂洗的鲅鱼鱼糜)相比,臭氧水漂洗的鲅鱼鱼糜中醛类、醇类、烯烃类、硫醚类、烷烃类等挥发性物质含量显著减少(P<0.05)。同时,臭氧水漂洗导致了蛋白质发生一定程度的氧化。随着臭氧水浓度的增加,肌原纤维蛋白羰基含量逐渐增加,总巯基含量明显降低。拉曼光谱谱图显示肌原纤维蛋白二级结构发生了变化:α-螺旋转变为β-折叠、β-转角、无规则卷曲。色氨酸、酪氨酸以及疏水性氨基酸等残基从蛋白质内部暴露到极性环境中。SDS-PAGE电泳结果表明臭氧水漂洗的鱼糜肌原纤维蛋白分子间发生一定程度的交联和聚集。综上,臭氧水漂洗可以改善鲅鱼鱼糜色泽和风味,同时也能引起肌原纤维蛋白氧化,导致蛋白质的结构和构象发生改变。     

Stability of Mackerel Surimi Prepared under Lipid-Stabilizing Processing Conditions

Surimi from mackerel whole and light muscle was prepared under conditions designed to minimize oxidation and development of rancidity. The lipid-stabilizing procedure included early addition of both lipid-and water-soluble antioxidants, avoidance of added sodium chloride, and exclusion of oxygen. Surimi prepared from light muscle was stable to rancid odor development in both the raw and cooked form; gel strength was reasonably stable during frozen storage, although the color was somewhat dark. Surimi prepared from mackerel whole muscle was darker, its odor quality lower and less consistent, and its gel strength lessened more rapidly during frozen storage than surimi prepared from light muscle.     

Gel Strengthening Effect of Wood Extract on Surimi Produced from Mackerel Stored in Ice

ABSTRACT:  The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel ( Rastrelliger kanagurta ) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously ( P  < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.     

Color and Quality of Mackerel Surimi as Affected by Alkaline Washing and Ozonation

Washing with alkaline phosphate or bicarbonate buffers (>pH 8.0) did not remove the pigments from minced mackerel. Thirty min ozonation in citrate buffer (pH 3.0) increased the whiteness (51.7 to 60.1) and L value (53.9 to 62.6), and decreased myoglobin (47.8 to 12.2 mg/100g) and total pigments (78.5 to 15.5 mg/100g). However, the deformation of surimi decreased from 0.90 cm to 0.45 cm, even though there was no change in breaking force. In comparison with untreated sample, addition of 0.10% NaHSO₃, 0.15% cysteine or 0.20% ascorbic acid during grinding resulted in substantial recovery of the deformation and breaking force of ozonated surimi.     

Quality Improvement of Mackerel Surimi with NADPH-Sulfite Reductase from Escherichia coli

The application of NADPH‐sulfite reductase, produced from Escherichia coli, on mackerel surimi was investigated. The activity of this reductase was very stable. There was about 70%, 80%, and 90% activity left even after 8–wk storage at 25 °C and 12–wk storage at 4 or ‐30 °C, respectively. Increase in mackerel‐surimi gel properties containing reductase was consistent with the amounts of reactive sulfhydryl groups detected. SDS‐PAGE indicated that NADPH‐sulfite reductase could reconstitute myosin heavy‐chain and increase soluble actomyosin. From the data obtained, E. coli NADPH‐sulfite reductase effectively improved the gel properties of mackerel surimi.     

碱性pH对马鲛鱼肌球蛋白热聚集行为的影响

为探究碱性条件下pH对马鲛鱼肌球蛋白热聚集行为的影响,以马鲛鱼肌球蛋白为研究对象,探究在加热条件下pH（7.0、8.0、9.0）对肌球蛋白的结构和理化性质（溶解度、浊度、二级结构、总巯基含量、表面疏水性）的影响,未加热组作为空白对照组。结果表明：对照组肌球蛋白在pH（7.0、8.0、9.0）下溶解度从68.00%升高到82.00%、浊度变化不明显;加热组则有较大差异,溶解度从30.00%增加到94.00%,浊度吸光值从0.49降低到0.23;加热组pH 9.0的肌球蛋白α-螺旋含量减少,在所有组中含量最低,为45.60%,β-折叠含量增加,为10.60%;加热组的巯基含量呈下降趋势,由70.45 nmol/mg减少到50.11 nmol/mg,碱性pH下的蛋白质有助于巯基向分子间和分子内二硫键的转化;随着pH值的增加,对照组肌球蛋白的表面疏水性系数依次增加,而加热组下降,但加热组肌球蛋白的表面疏水性系数仍然远高于对照组。综上所述,通过探究碱性条件下肌球蛋白热聚集体的性质,有助于对其热聚集进行调控,获得一种热稳定性较好的肌球蛋白溶液,对以后研究其作为乳化剂添加到食品中有重要意义。     

Thermal Gel Degradation (Modori) in Sturgeon (Acipenseridae) Surimi Gels

Sturgeon meat has been found to be suitable as surimi raw materials. The present study determined the modori phenomenon in sturgeon surimi gels and identified its relationship with cathepsins. In all heat‐treated gels (25 to 90 °C, at 5 °C intervals), the 40 °C‐incubated sturgeon surimi gel showed the weakest gel properties and water‐holding capacity (P < 0.05), a rough protein gel network under SEM, and the highest protein solubility and trichloroacetic acid‐soluble peptides content (P < 0.05). SDS‐PAGE indicated that the myosin heavy chain band of sturgeon surimi gels was almost completely degraded at 40 °C. Moreover, the highest cathepsin L activity was observed in 40 °C‐treated sturgeon surimi gels (P < 0.05). Our results suggested that the modori phenomenon in sturgeon surimi gels occurred at 40 °C, which was partially attributed to cathepsin L, thereby allowing for the better exploitation and utilization of sturgeon surimi.     

苹果多酚改性蛋清改善鲅鱼鱼糜的凝胶性质

为探讨苹果多酚改性蛋清对鲅鱼鱼糜性质的作用机制,将质量比分别为0.50%、0.75%、1.00%、1.25%、1.50%苹果多酚改性的蛋清加入鱼糜中,与控制组（只添加蛋清）及空白组对比,通过测定凝胶特性;测定鱼糜凝胶的TVB-N、菌落总数、TBARS、以及TPA参数随贮藏时间的变化;检测鲅鱼鱼糜肌原纤维蛋白的圆二色谱、及紫外吸收光谱。结果显示添加苹果多酚改性蛋清的鱼糜凝胶强度（2962.81、3342.79、3088.05、2527.83、2147.12 mm?g）、持水性（0.87%、0.85%、0.87%、0.86%、0.86%）有着显著性的提升（p<0.05）,随着苹果多酚浓度的增加,鱼糜的L*（亮度）从69.58降至64.10,a*（红绿值）从-1.83升至1.23（p<0.05）;鱼糜凝胶硬度、弹性、回复性存在先上升后下降的趋势;在贮藏期内,挥发性盐基氮值、过氧化值和菌落总数值相对于空白组均有显著性下降（p<0.05）。经过苹果多酚改性蛋清处理的鱼糜肌原纤维蛋白,0.5% AP-EW组相对于空白组的α-螺旋含量增加了1.87%,β-转角和无规卷曲相对含量有降低。结果证明苹果多酚改性蛋清的添加可显著提高鲅鱼鱼糜的凝胶性质。     

Thermal Gel Degradation (Modori) in Sardine Surimi Gels

Sardine (Sardina pilchardus) surimi gels set (50°C or 60°C), or set and cooked (50°C or 60°C + 90°C) for different times were studied in order to evaluate modori (thermal gel degradation). The texture data of the set gels were similar to data obtained previously in gels set at lower temperature that produced good kamaboko gels. However, in gels set at 50°C and 60°C modori occurred upon cooking. Microscopically the set gels exhibited globular aggregated structures that became more compact when modori occurred. Results suggested that at modori temperature protein-protein bonding caused massive protein coagulation preventing the formation of a fibrillar matrix upon cooking.     

Ionic Strength Effects on Heat-induced Gelation of Myofibrils and Myosin from Fast- and Slow-twitch Rabbit Muscles

The effects of ionic strength on myofibrils and myosin from rabbit fast-twitch Psoas major (PM) and slow-twitch Semimembranosus proprius (SMp) muscles before and after heating were studied by electron microscopy and thermal scanning rheometry. The direct suspension of proteins in low ionic strength (0.2M KCl; pH 6.0) led to very weak gels, whereas a gradual lowering of the ionic strength (by dialysis against 0.2M KCl; pH 6.0) of 0.6M KCl protein solutions induced strand-type networks at low temperature and strong heat-induced gels. As shown by transmission and scanning electron micrographs, in low ionic strength, SMp myosins formed shorter filaments before heating and thinner and shorter structures in heat-induced gels, as well as a lower gel porosity than PM myosins.     

Pediococcus pentosaceus L and S Utilization in Fermentation and Storage of Mackerel Sausage

ABSTRACT During 72 h fermentation at 37 °C, rapid increase in lactic acid bacteria count (LAB), dramatic decline in pH and suppression in the growth of contaminating Pseudomonas, Staphylococcus, and Enterobacteriaceae of mackerel minces with Pediococcus pentosaceus strains L and S were observed (p < 0.05). When the mackerel mince was processed into Chinese style sausage with 4% sucrose, no significant changes in pH, growth of LAB, Aerobic Plate Count, and Pseudomonas of the fermented mackerel sausage with Pediococcus pentosaceus strains L and S were obtained (p > 0.05) during 3 wk storage at 4 °C, however, the growth of Enterobacteriaceae and Staphylococcus were effectively suppressed. The residual nitrite in sample decreased during processing and fermentation, and was minimally detected after 72 h fermentation. Suppression of VBN and psychrophilic microflora, and lowering residual nitrite suggest the potential of using these 2 strains in the fermented fish products.     

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。     

Proteolytic Degradation of Tropical Tilapia Surimi

Proteolytic degradation of tropical tilapia surimi was biochemically and rheologically characterized to identify a group of proteinase(s) responsible for its textural degradation. Proteolysis of tilapia surimi occurred as the temperature increased and attained the highest activity at 65 °C. Smaller proteins with molecular weight of 116-97 kDa were noted as a result of myosin heavy chain (MHC) degradation. MHC completely disappeared when incubated at 65 °C for 4 h. Proteolysis was significantly inhibited by soybean trypsin inhibitor (SB) and leupeptin (LE). Storage modulus (G') of surimi gels mixed with either SB or LE was higher than other inhibitors indicating that serine type proteinase(s) were involved in proteolysis of tropical tilapia surimi.     

Predictive Models for Microbial Inactivation and Texture Degradation in Surimi Seafood During Thermal Processing

Models for Staphylococcus aureus inactivation and texture degradation during thermal processing of surimi seafood were developed based on the modified thermal‐death‐time (TDT) concept. Validation studies showed good fit between experimental and predicted values. The models allow input of processing parameters, resulting in a surface response that determines microbial inactivation and texture degradation. D‐values for microbial inactivation were determined between 55 and 95 °C. The z‐value, however, was not linear. Therefore, a polynomial equation was used to calculate D‐values at intermediate temperatures. Texture degradation between 55 and 95 °C followed a power function. Therefore, power “n” was used as the degradation rate for modeling purposes. Polynomial equation was used to calculate “n” at intermediate temperatures.     

热处理条件对竹荚鱼鱼糜凝胶特性的影响

研究加热条件对竹荚鱼鱼糜凝胶特性的影响,主要采用质构分析法、扫描电镜法、持水力、白度、TCA-可溶性肽含量和鱼糜凝胶溶解度的测定等方法研究凝胶化温度、凝胶化时间和加热方式对竹荚鱼鱼糜凝胶特性的影响。结果表明：凝胶化温度、凝胶化时间和加热方式影响竹荚鱼鱼糜的凝胶特性。竹荚鱼鱼糜凝胶的制备宜采用30℃凝胶化5h 或40℃凝胶化4h,然后90℃加热20min 的二段加热方式,竹荚鱼鱼糜形成了高度致密、均一的三维网络结构。50～70℃凝胶化后,竹荚鱼鱼糜形成大小不一的凝胶孔洞,凝胶网络的致密性下降,呈现出明显的凝胶劣化现象。     

不同冷冻温度对鲅鱼理化指标及新鲜度的影响

以pH、挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量、硫代巴比妥酸值(thiobarbituric acid,TBA)和肌原纤维蛋白含量等理化指标,结合感官评价,分析了-50、-30和-18℃ 3种冻结温度下鲅鱼新鲜度差异。采用电子鼻技术,获取了不同冻结温度处理后鲅鱼的气味信息,利用主成分分析(principal component analysis,PCA)法处理了电子鼻气味信息数据,建立一种快速区分鲅鱼新鲜度的方法。结果表明,不同冻结温度处理后鲅鱼的新鲜度存在显著差异(p<0.05),-50℃冻结组综合新鲜度显著优于另两组,其中TVB-N和TBA值显著低于另外两组(p<0.05),而pH和肌原纤维蛋白含量显著高于另外两组(p<0.05),同时,-50℃冻结组感官评分也优于其他两组。电子鼻结果显示,电子鼻对各个温度下冻结的鲅鱼肉响应灵敏,区分结果同理化和感官评价结果相一致,能有效区分出不同冻结温度下鲅鱼肉气味差异,表明电子鼻技术可以作为一种区分冻结鲅鱼新鲜度的快速检测手段。     

Cathepsin Degradation of Pacific Whiting Surimi Proteins

Cathepsin B was the most active cysteine protease in Pacific whiting fish fillets; cathepsin L was predominant in surimi. Cathepsin L showed highest activity at 55°C in both fish fillets and surimi, indicating its function in myosin degradation during conventional heating of fillets and surimi, gels. Washing during surimi processing removed cathepsin B and H but not cathepsin L. Myosin heavy chain was the primary substrate during autolysis of surimi paste and actin and myosin light chain showed limited hydrolysis during 2 hr incubation. Purified Pacific whiting cathepsin L hydrolyzed myofibrils, myosin and native and heat-denatured collagen. The degradation pattern of myofibrils by the protease was the same as the autolytic pattern of surimi.