N-Nitrosodimethylamine Formation in Cooked Frankfurters Containing Alaska Pollock (Theragra chalcogramma) Mince and Surimi

Studies were conducted to determine the feasibility of using Alaska pollock mince as a partial substitute for red meats in the formulation of frankfurters. Studies included the effects of fish form (unwashed and washed mince and surimi), percentage substitution (15 and 50) and five different methods of cooking the fish-meat franks on their N-nitrosodimethylamine (NDMA) content. The amount of formed NDMA depended on the method of cooking. Broiling and frying generated the highest levels. Microwave and boiling generated the lowest levels of NDMA, which were equivalent to the level in uncooked franks. Broiling was observed to increase the amount of dimethyl-and trimethylamine formed.     

Effect of rainbow trout (Oncorhynchus mykiss) plasma protein on the gelation of Alaska pollock (Theragra chalcogramma) Surimi

ABSTRACT:  The effect of rainbow trout plasma protein (RPP) on the gelation of Alaska pollock surimi was determined to evaluate the possibility of its commercialization as a new protein additive. For modori gel, the breaking force, deformation, whiteness, and water holding capacity increased as the addition amount of RPP (0 to 0.75 mg/g) increased, and decreased at higher concentration of RPP (0.75 to 1.50 mg/g) ( P < 0.05). Protein solubility of modori gel in the mixture of SDS, urea, and β-mercaptoethanol decreased as the addition amount of RPP increased up to 0.75 mg/g, and increased at higher concentration of RPP (0.75 to 1.50 mg/g) ( P < 0.05). The contents of trichloroacetic acid-soluble peptide decreased as the addition amount of RPP (0 to 1.50 mg/g) increased ( P < 0.05). Based on the result of sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), most myosin heavy chain of surimi was not degraded when RPP was added. Thus, RPP was supposed to act as a protease inhibitor in the gelation of Alaska pollock surimi. An RPP of 0.75 mg/g was the optimal concentration to prevent the gel weakening of Alaska pollock surimi. Compounds with molecular weights less than 10 kDa in RPP had no significant effect on the gelation of Alaska pollock surimi based on the result of the dialyzed RPP.     

Physicochemical Changes in Alaska Pollock Surimi and Surimi Gel as Affected by Electron Beam

ABSTRACT: Alaska pollock surimi and surimi gels (cooked) were subjected to various doses of electron beam (e-beam). Shear stress of surimi gels increased as the dose increased up to 6 to 8 kGy and then decreased. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed gradual degradation of myosin heavy chain as the dose increased. The degradation was slower for frozen samples. The integrity of actin was slightly affected by high doses (25 kGy). The amount of sulfhydryl groups and the level of surface hydrophobicity of Alaska pollock surimi decreased as the dose increased, suggesting formation of disulfide bonds and hydrophobic interactions. The sulfhydryl groups and hydrophobicity of surimi gels increased as the dose increased up to 6 kGy and then decreased.     

Characterization of protein fractions from immature Alaska walleye pollock (Theragra chalcogramma) roe

ABSTRACT:  There are good markets for mature pollock roe; however, immature pollock roe is underutilized. The physical and nutritional properties of immature pollock roe (IPR) have not been reported, which limits its potential use as a food ingredient. The objective of this study was to evaluate the physical and nutritional properties of immature pollock roe and soluble and insoluble protein powders made from the immature roe. IPR samples were obtained during the spring pollock harvest from a seafood processing plant in Kodiak, Alaska. Soluble (SP) and insoluble protein (IP) fractions were produced by heating IPR, separating by centrifugation and freeze drying. The protein contents of freeze-dried IPR, SP, and IP were 81.7%, 63.2%, and 83.0%, respectively. The amino acid contents of IPR and IP were similar except for isoleucine and valine. However, the amino acid contents of IPR and IP were different from values for SP. Lipid contents of IPR, SP, and IP were 9.2%, 9.3%, and 11.1%, respectively. Palmitic acid (C16:0; 21.2%), DHA (C22:6ω3; 21.2%), and EPA (C20:5ω3; 19.0%) were the 3 most abundant fatty acids in fresh IPR. Fat adsorption capacity value for SP was significantly higher than IPR and IP ( P < 0.05). SDS electrophoresis indicated a major protein band with molecular weight of 103 KDa in all samples. Results indicate that IPR can be utilized to make a number of unique food ingredients with good nutritional characteristics and functional properties.     

Application of recombinant chum salmon cystatin to Alaska pollock (Theragra chalcogramma) surimi to prevent gel weakening

ABSTRACT:  Recombinant chum salmon cystatin (RC) expressed in Saccharomyces cerevisiae was purified by His-select nickel affinity chromatography. The specific inhibitory activities of RC against papain and cathepsin L were 7.45 and 10.24 U/mg, respectively. RC was stable over pH 5.0 to 7.0 and at temperature below 65 °C. RC was used to prevent the gel weakening of Alaska pollock surimi. RC at 100 μg/g showed the highest inhibitory activity against the autolysis of surimi based on the analysis of TCA-soluble peptides. As the concentration of RC increased, both the breaking force and deformation of modori gel greatly increased ( P < 0.05). The addition of RC resulted in less expressible drip, which coincided with the increase of whiteness. More myosin heavy chain (MHC) was retained as the addition of RC increased. Therefore, RC could prevent the degradation of proteins in Alaska pollock surimi and was better than egg white (EW). Thus, RC could be applied to Alaska pollock surimi to prevent gel weakening and RC at 100 μg/g was the optimal concentration.     

近红外光谱技术快速无损测定狭鳕鱼糜水分和蛋白质含量

通过拟合狭鳕鱼糜的近红外漫反射光谱与其水分和蛋白质含量,建立近红外定量模型,用于狭鳕鱼糜水分和蛋白质的快速无损检测。模型采用偏最小二乘法(PLS)拟合,水分和蛋白质的定标模型相关系数分别达0.98 和0.96以上,优于近红外透射光谱建立模型的预测结果。模型的相对标准偏差(RSD)＜ 10%,相对分析误差(RPD)＞ 3,表明该模型能准确快速地测定狭鳕鱼糜中的水分和蛋白质含量,且可用于实际生产中。     

Fracture of Alaska Pollock Gels in Water: Effects of Minced Muscle Processing and Test Temperature

The effects of temperature on instrumental textural measurements of cooked Alaska pollock gels were evaluated. Independent variables were: raw materials (minced muscle, washed minced muscle alone or with cryoprotectants), cooking schedule (90°C for 20 min with/without preconditioning at 25°C) and test temperatures. Gels tested at 5°C were more brittle than those tested at 45–55°C. Gels preset at 25°C for 1 hr prior to cooking at 90°C had higher fracture shear stress values and were influenced differently by test temperatures than those not preset suggesting cooking history influenced structure of the gels at the molecular level. Results indicated gels set at 25°C were probably stabilized by more covalent bonds.     

Adenosine Triphosphate Catabolites as Flavor Compounds and Freshness Indicators in Pacific Cod (Gadus macrocephalus) and Pollock (Theragra chalcogramma)

Postmortem formation of 5′-inosine monophosphate, inosine and hypoxanthine in Pacific cod and pollock fillets during chilled storage was monitored over a two week period. Accumulation of hypoxanthine in Pacific cod (Gadus macrocephalus) fillets proceeded more slowly than has been reported for Atlantic cod (Gadus morhua) but similar to North Sea cod (Gadus callarias L.). For both both cod and pollock, hypoxanthine was negatively correlated with flavor and desirability (p < 0.01), while both inosine and 5′-inosine monophosphate were positively correlated with overall desirability (p < 0.01).     

Surimi Production from Partially Processed and Frozen Pacific Whiting (Merluccius productus)

Pacific whiting surimi was made from stabilized mince (SM), unstabilized mince (UM), and headed and gutted (H&G) fish kept in frozen storage and compared to a surimi control made from fresh fillets. SM was made by mixing fresh mince with 12% w/w sucrose and 0.2% w/w polyphosphates. Surimi was produced from SM, UM, H&G at 1, 30, 90, and 180 days and evaluated by torsion, measuring shear stress, and true strain. After 6 months, there were no differences (p>0.05) between surimi samples prepared from SM stored at - 20° and -50° and the control surimi. UM and H&G fish produced surimi of inferior quality.     

Suppression of Thermal Denaturation of Myosin Subfragment-1 of Alaska Pollack (Theragra chalcogramma) by Sorbitol and Accelerated Inactivation by Pyrophosphate

Thermal denaturation of myosin subfragment-1 (S-1), prepared from myofibrils (Mf) of Alaska pollack dorsal muscle by chymotryptic digestion, was well suppressed by sorbitol addition in a concentration dependent relationship. ATP and ADP also suppressed the ATPase inactivation significantly at different degrees. On the contrary, pyrophosphate (PPi) accelerated the inactivation by several-fold; half the maximal acceleration occurred at about 30 μn, M PPi concentration. The accelerated inactivation by PPi addition was remarkable at high-salt medium such as 0.5M KC1.     

Enzymatic hydrolysis of Alaska pollack (Theragra chalcogramma) skin and antioxidant activity of the resulting hydrolysate

BACKGROUND: Fish skin, a by‐product of the food industry, contains a large amount of collagen. However, only a small proportion of fish skin is used in the production of leather materials and animal feedstuffs, most of it being discarded. The aims of this study were to prepare peptides from Alaska pollack (Theragra chalcogramma) skin by enzymatic hydrolysis and to evaluate the antioxidant activity of the resulting hydrolysate. RESULTS: Protamex was the most efficient enzyme for preparing antioxidant peptides from Alaska pollack skin. The optimal hydrolysis conditions were as follows: hydrolysis time 8 h; enzyme/substrate ratio 2:1000; skin/water ratio 1:6; temperature 55 °C; pH 6.0. Under these conditions the highest yield of peptides was 83.44%, with 85.95% of the hydrolysate being mainly composed of oligopeptides with molecular weights ranging from 180 to 1000 Da. The hydrolysate showed 2,2‐diphenyl‐1‐picrylhydrazyl radical‐scavenging activity, with an IC₅₀ value of 2.5 mg mL^?1, and its reducing power was 0.14 at 1 mg mL^?1, 53.8% of that of reduced glutathione at the same concentration. CONCLUSION: This study demonstrated that the hydrolysate of Alaska pollack skin was mainly composed of oligopeptides with two to eight amino acid residues and possessed antioxidant activity. Copyright © 2010 Society of Chemical Industry     

鱼鱼肉与白鲢鱼鱼糜混合热聚集行为分析

为了研究不同混合比例下鳀鱼鱼肉与白鲢鱼鱼糜的热聚集行为,本文以凝胶强度、动态流变、热稳定性、粒径、内源荧光、拉曼光谱和扫描电子显微镜作为测定指标。当鳀鱼鱼肉与白鲢鱼鱼糜的质量比例为1:9和2:8时,混合体系的凝胶强度可达到7568.01和6804.22 g·mm。当鳀鱼鱼肉与白鲢鱼鱼糜的质量比例为0:10、1:9和2:8时,混合体系的热稳定性和储能模量最高。随着加热的进行,混合体系的最大荧光强度逐渐降低,与未加热时相比,第一段加热后(40 ℃,30 min)和第二段加热后(40 ℃,30 min;90 ℃,20 min)分别降低了38.8%和44.4%。当鳀鱼鱼肉与白鲢鱼鱼糜的质量比例为1:9时,二段式加热后混合体系中的α-螺旋相对含量最低,β-折叠相对含量最高;微观结构最为致密。结果表明,当鳀鱼鱼肉与白鲢鱼鱼糜的质量比例为1:9时,混合体系的热聚集效果最佳。     

罗非鱼与四种海水鱼鱼糜比较

比较了罗非鱼与工厂常用的四种海水鱼(黄姑鱼、带鱼、沙丁鱼、鲜丁鱼)鱼糜的基本成分含量、凝胶性能及鱼肌肉蛋白的营养价值。罗非鱼与海水鱼鱼糜的水分含量无显著差异(p>0.05),但蛋白质、脂肪、灰分、盐溶性蛋白含量及pH值有显著差异(p<0.05);罗非鱼鱼糜凝胶的强度、白度显著高于海水鱼(p<0.05),而凝胶的持水性显著低于海水鱼(p<0.05);通过分析几种鱼肌肉蛋白的必须氨基酸含量、氨基酸价(AAS)及氨基酸指数(EAAI),得出罗非鱼肌肉蛋白的营养价值高于黄姑鱼、带鱼和鲜丁鱼,但低于沙丁鱼。     

复合果蔬取代部分硝酸盐对降低发酵香肠中亚硝胺的作用

分析复合果蔬替代硝酸盐对发酵香肠中N-亚硝胺生成的影响,探究发酵香肠生产过程中复合果蔬取代部分硝酸盐的可能性。制备4 组中式发酵香肠：阴性对照组（negative control group,NCG,空白组）、阳性对照组（positive control group,PCG）、芹菜樱桃组（celery and cherry group,CCG）、卷心菜番茄组（cabbage and tomato group,CTG）,考察在发酵及成熟过程中亚硝酸盐、亚硝胺及生物胺含量的变化。结果表明：发酵过程中,果蔬发酵香肠（CCG和CTG）与PCG亚硝酸盐含量同样呈现先增加后降低趋势,但CTG峰值（65.52?mg/kg）显著低于PCG（105.31?mg/kg）。4?组发酵香肠均能检出N-二乙基亚硝胺（N-nitrosodiethylamine,NDEA）,而果蔬发酵香肠（CCG和CTG）在发酵后期NDEA含量（1.23 μg/kg未检出）显著低于PCG（3.72 μg/kg）。干燥成熟阶段,果蔬发酵香肠（CTG和CCG）亚硝酸盐残留量（36.45?mg/kg和47.97?mg/kg）显著高于NCG（24.49?mg/kg）和PCG（31.40 mg/kg）,但在干燥3 d后下降至国家标准限量（30 mg/kg）以下。成品中总生物胺含量排序为NCG＞PCG＞CCG＞CTG,CTG中未检出组胺和酪胺。各组样品中N-二甲基亚硝胺（N-nitrosodimethylamine,NDMA）（PCG除外）和NDEA含量均随干燥进程而逐渐增加,但是果蔬发酵香肠（CCG和CTG）在干燥结束时NDMA（0.16?μg/kg和0.11?μg/kg）和NDEA含量（4.33?μg/kg和4.13?μg/kg）低于NCG（1.73?μg/kg和9.50?μg/kg）,与PCG（0?μg/kg和4.74?μg/kg）相当。实验表明复合果蔬浆替代部分硝酸盐,可降低中式发酵香肠的N-亚硝胺和生物胺含量。     

发酵食品有害氨(胺)类代谢物:形成机制和消除策略

影响我国传统发酵食品安全最为重要的因素是各种含氮化合物代谢生成的有害胺(氨)类物质,如氨基甲酸乙酯、亚硝胺类和生物胺类等.以往基于生物化学和分子生物学的研究,已经阐明了与这些有害胺(氨)类物质相关的代谢途径及调控途径.在此基础上,研究人员通过一系列的代谢工程操作试图消除这些有害胺(氨)类物质的积累,但实际效果有限.近年来的研究表明,有害胺(氨)类物质的积累,与食品发酵过程中微生物对氨基酸等有机氮源的选择性吸收密切相关.由于部分氨基酸的滞后吸收,导致最终氨基酸无法有效利用,甚至被代谢为有害胺(氨)类物质.微生物对氮源的利用受到氮代谢物阻遏(Nitrogen Catabolite Repression,NCR)效应的严谨调控.对于NCR效应这一全局调控机制的解析,将对理解微生物积累有害胺(氨)类物质的机理,并进行有效消除,奠定良好的基础.本文综述了发酵食品有害胺(氨)类物质积累和NCR效应的研究进展,在此基础上提出利用对NCR效应的理性调控消除有害胺(氨)类物质积累的系统策略.     

Effect of cold atmospheric plasma on the physicochemical and functional properties of myofibrillar protein from Alaska pollock (Theragra chalcogramma)

This study aimed to investigate the effect of cold atmospheric plasma (CAP) on the physicochemical and functional properties of myofibrillar protein isolated from Alaska pollock (Theragra chalcogramma) muscle. Free sulfhydryl content, surface hydrophobicity, turbidity, differential scanning calorimetry, SDS-PAGE, heat-induced myofibrillar protein gel properties and water holding capacity were determined to evaluate the effect of CAP treatment on protein properties. CAP treatment from 10 to 60 kV for 10 min significantly (P < 0.05) increased the water holding capacity, textural properties and colour properties of heat-induced myofibrillar protein gel. As treatment voltage increased, free sulfhydryl content decreased significantly, while the turbidity and surface hydrophobicity of myofibrillar protein were increased. DSC data showed enhancement of thermal stability of the treated samples; however, the electrophoretic profile displayed a significant reduction in the band's intensity of protein at a higher voltage. These results suggest that cold atmospheric plasma (CAP) treatment could be used as an alternative approach to enhance the gelling properties of myofibrillar protein from Alaska pollock.     

性早熟蟹肉和白鲢鱼糜混合凝胶工艺优化及其凝胶特性

通过向白鲢鱼糜中添加蟹肉和0.3%谷氨酰胺转氨酶（transglutaminase,TG）,以凝胶强度和持水性为指标,研究蟹肉比例、凝胶化时间以及凝胶化温度3 个因素对混合凝胶特性的影响。在单因素试验基础上,采取3因素3水平的Box-Behnken设计进行响应面分析,得到最佳工艺条件为：蟹肉比例10%,凝胶化时间3.0 h,凝胶化温度35 ℃。验证实验结果显示,与传统鱼肠相比,优化后的鱼糜与蟹肉混合肠,其凝胶强度有显著的提升（P＜0.05）,持水性略有降低,但并不显著（P＞0.05）;聚丙烯酰胺凝胶电泳和扫描电镜结果表明,TG的添加可使混合凝胶中肌球蛋白重链明显减少,且凝胶表面更均匀、致密。     

Biogenic Amines Formation in Fish Sauce Prepared from Fresh and Temperature-abused Indian Anchovy (Stolephorus indicus)

ABSTRACT: The formation of biogenic amines in fish sauce made from fresh and temperature-abused (left at 35°C for 8 and 16 h) Indian anchovy ( Stolephorus indicus ) was investigated. Histamine, cadaverine, putrescine, and tyramine were the predominant biogenic amines found in anchovy left at 35°C for 16 h and its fish sauce product. Changes of biogenic amines were subtle during the course of fermentation at room temperature (RT) and at 40°C, suggesting that the main source of biogenic amines was associated with raw material, rather than with the fermentation process. Soluble peptide and total nitrogen of fish sauce prepared from temperature-abused anchovy were higher at the initial stage of fermentation at RT and 40°C and became comparable to those prepared from fresh anchovy at the end of fermentation. Total free amino acid contents of samples fermented at RT for 52 wk (7208.3 to 8473.6 mg/100 mL) were higher than those fermented at 40°C for 13 wk (4560.9 to 5730.9 mg/100 mL). Fish sauce prepared from temperature-abused anchovy contained less free histidine and arginine. Fish sauce of a good quality was obtained using fresh anchovy fermented at RT. Besides total nitrogen content, biogenic amines should be considered as quality indicators of fish sauce.     

棒状乳杆菌发酵秘鲁鱿鱼糜凝胶特性的变化及其形成机理

为阐明棒状乳杆菌（Lactobacillus coryniformis）Lz153发酵秘鲁鱿鱼糜的凝胶形成机理,通过质构仪测定棒状乳杆菌Lz153发酵秘鲁鱿鱼糜凝胶特性,分析凝胶形成过程中离子键、氢键、疏水相互作用、二硫键及非二硫共价键的变化,并利用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）方法观察肌原纤维蛋白变化情况。结果表明,棒状乳杆菌Lz153鱿鱼糜发酵24～36?h阶段凝胶特性最佳;离子键含量在发酵过程中呈逐渐减少趋势,氢键和疏水相互作用含量分别在发酵36?h和30?h达到最大值,二硫键和非二硫共价键含量随发酵时间延长而呈增加的趋势;氢键、疏水相互作用、二硫键和非二硫共价键是形成和维持凝胶网络的主要作用力。SDS-PAGE图谱显示,发酵后肌动蛋白和肌球蛋白重链均开始被降解,同时经发酵24?h后分子质量在100～135?kDa范围出现了新的盐溶性蛋白质条带,发酵至48?h也被降解。研究结果可为开发秘鲁鱿鱼为原料的乳酸菌发酵鱼糜制品加工提供参考依据。     

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%。