Microbial Inactivation and Electron Penetration in Surimi Seafood During Electron Beam Processing

Electron penetration and microbial inactivation by electron beam (e‐beam) in surimi seafood were investigated. Dose map revealed that 1‐ and 2‐sided e‐beam could efficiently penetrate 33‐ and 82‐mm thick surimi seafood, respectively. Modeling of microbial inactivation by e‐beam demonstrated that 2‐sided e‐beam may control Staphylococcus aureus if the surimi seafood package is thinner than 82 mm. The D_e‐beam value for S. aureus was 0.34 kGy. An e‐beam dose of 4 kGy resulted in a minimum of a 7‐log and most likely a 12‐log reduction of S. aureus. Microbial inactivation was slower when frozen samples were subjected to e‐beam.     

Chemical properties of surimi seafood nutrified with ω-3 rich oils

Surimi-based seafood products are widely accepted and enjoyed worldwide. The US consumption increased in 1980s; however, it leveled thereafter. Food products nutrified with ω-3 polyunsaturated fatty acids (PUFAs) are in increasing demand due to demonstrated health benefits. Currently, surimi seafood is not nutrified with ω-3 PUFAs. In the present study, surimi seafood was nutritionally-enhanced with ω-3 PUFAs-rich oils (flaxseed, algae, menhaden, krill, and blend). The objectives were (1) chemical characterization of FA composition and oxidation, and (2) determination of physicochemical properties (colour and texture) of the nutritionally-enhanced surimi seafood. Oil addition resulted in increased (P < 0.05) concentration of total ω-3 FAs in surimi seafood; however, the concentration of α-linolenic (ALA, 18:3ω-3), eicosapentaenoic (EPA, 20:5ω-3) and docosahexaenoic (DHA, 22:6ω-3) acids depended on which oil was added. Although the ω-3 PUFAs nutrification resulted in increased (P < 0.05) susceptibility of surimi seafood to lipid oxidation, it was within ranges acceptable to consumers. Texture analysis (texture profile analysis, Kramer shear and torsion test) showed that ω-3 PUFAs nutrification did not affect texture. Colour properties of ω-3 PUFAs nutrified surimi seafood were generally improved except when krill oil or blend was added. This study demonstrates that nutritional value of surimi seafood can be enhanced with concurrent improvement of colour and without affecting texture.     

Dynamic rheology and thermal transitions of surimi seafood enhanced with ω-3-rich oils

Surimi-based seafood products are widely accepted and enjoyed worldwide. The U.S. consumption increased in 1980s; however, it leveled thereafter. Food products nutrified with ω-3 polyunsaturated fatty acids (PUFAs) are in increasing demand due to demonstrated health benefits. Currently, surimi seafood is not nutrified with ω-3 PUFAs. In the present study, surimi seafood was nutritionally-enhanced with ω-3 PUFAs-rich oils (flaxseed, algae, menhaden, krill, and blend). Protein endothermal transitions, heat-induced gelation (elastic modulus, G′), and fundamental texture properties (shear stress) of Alaska pollock surimi nutrified with ω-3 PUFAs-rich oils (flaxseed, algae, menhaden, krill, and blend) were determined and compared to Alaska pollock surimi without oil (control). Differential scanning calorimetry showed that oil addition enhanced thermal transition of actin and did not compromise the transition of myosin. The addition of oil improved heat-induced protein gelation as demonstrated with dynamic rheology. Elastic modulus increased when oil was added. There were no differences (P > 0.05) in shear stress between surimi gels with and without oil, indicating that nutrification with ω-3 PUFAs-rich oils within the ranges tested did not alter gel strength. This study demonstrates that the nutritional value and gelation of surimi seafood can be enhanced without altering texture properties by addition of ω-3 PUFAs-rich oils.     

Negative Roles of Salt in Gelation Properties of Fish Protein Isolate

ABSTRACT: Salt effect on gelling properties of fish protein isolate (FPI) prepared by acid‐ and alkali‐aided extraction was investigated. Acid‐ or alkali‐extracted FPI formed significantly better gel texture with 0% NaCl than with 3% NaCl. Texture properties of acid‐ or alkali‐extracted FPI decreased as NaCl content increased, especially at 2% to 3% salt. Contrarily, salt significantly promoted texture qualities of conventional surimi gels. The effect was highlighted when they were subjected to low temperature setting. The myofibrillar proteins in FPI were not solubilized when NaCl was added, perhaps due to protein aggregation caused by acid or alkali extraction. FPI solubility, however, was not closely related to their texture properties. Cold setting did not promote texture properties of FPI gels as much as conventional surimi gels. Acid‐extracted gels gave the best color properties.     

A NONLINEAR PROGRAMMING TECHNIQUE TO DEVELOP LEAST COST FORMULATIONS OF SURIMI PRODUCTS

Optimization programming techniques were applied to develop the least cost formulations for Pacific whiting surimi-based seafood (PWSBS). To develop the quality constraint functions, texture and color of whiting surimi gels were determined by torsion test and colorimeter, respectively. Whiting surimi gels were produced by heating at 90C for 15 min with 2% NaCl, five final moisture contents (74, 76, 78, 80, 82%), and various combinations of beef plasma protein (0–2%), potato starch (0–8%), and two whey protein concentrates (0–8%). Due to the nonlinear constraint functions describing texture and color, a nonlinear programming search technique was required to solve the least cost model for PWSBS. Results for representative target quality constraints are reported in this study and show that whey protein concentrate both increases the texture properties and remains economically competitive with other ingredients which similarly influence functionality in PWSBS.     

Physicochemical changes in surimi with salt substitute

Protein endothermic transitions (thermal denaturation), rheological properties (protein gelation), and fundamental texture properties (shear stress and strain at mechanical fracture) of Alaska pollock surimi gels made with 0 (control), 1, 2, and 3 g/100 g of salt (NaCl) were determined and compared with equal molar concentration of salt substitute. Salt and salt substitute shifted the onset of myosin transition to higher temperature and resulted in larger myosin peaks (i.e., transition enthalpy). Endothermic transitions showed similar trends to rheological properties. The elastic modulus (G′) increased when salt or salt substitute was added to surimi, except at the highest concentration of salt and salt substitute. Salt and salt substitute also induced the onset of protein gelation (i.e., as measured by significant increase of G′) at lower temperature. Surimi gels with salt substitute and salt at equal molar concentrations had similar texture properties (shear stress and strain). Based on the present study, salt substitute can be used in the development of low-sodium surimi seafood products without significant change in gelation and texture.     

添加微细鲽鱼鱼骨泥对金线鱼鱼糜凝胶品质的影响

以鲽鱼骨为研究对象,首先采用湿法超微粉碎技术将其加工成微细骨泥,再将其添加到金线鱼鱼糜制品中开发高钙鱼糜制品,从鱼糜溶胶pH值、肌原纤维蛋白Ca2＋-ATP酶活力、凝胶强度、质构、持水性、色泽、凝胶溶解度、微观结构方面探讨添加不同质量分数（2.5%～12.5%）鱼骨泥对鱼糜制品凝胶品质的影响。结果显示：添加微细鱼骨泥不影响鱼糜正常凝胶的pH值;较低质量分数（不超过5.0%）时,鱼骨泥中的Ca2＋可以激活鱼糜溶胶中肌原纤维蛋白的ATP酶,显著提升Ca2＋-ATP酶活力;鱼糜凝胶的凝胶强度、质构、持水性、色泽指标均在添加质量分数5.0%鱼骨泥时达到最高值,而凝胶溶解度达到最低值。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析和扫描电子显微镜观察结果表明,添加质量分数2.5%～5.0%鱼骨泥一定程度上促进了肌球蛋白重链（myosin heavy chain,MHC）的交联,可以促进鱼糜凝胶形成致密均匀的网状结构,过量添加则会影响MHC交联和凝胶网络致密性。     

不同还原糖对鲢鱼肉糜凝胶品质的影响

鲢鱼蛋白质凝胶性差、鱼腥味重是限制其精深加工的主要原因。为了探究糖基化对鲢鱼肉糜凝胶色泽、质构及风味等的影响,选取葡萄糖、低聚异麦芽糖、葡聚糖、L-阿拉伯糖和木糖作为还原糖。利用紫外分光光度计、色差仪、pH计、质构仪和感官评价测定样品的接枝度、色泽、pH值、质构和风味变化。结果表明:添加L-阿拉伯糖和木糖的鲢鱼肉糜凝胶的接枝度高达(58.24±0.62)%和(61.89±2.06)%,与未加糖的对照组相比,2组样品的pH值显著下降(P<0.05),褐变和质构指标显著增加(P<0.05);定量描述分析发现,糖基化可以降低鲢鱼肉糜凝胶的鱼腥味,增加肉香味、烤味和烧焦味;喜好度评价表明,要控制接枝度为44.85%～61.89%,才能获得整体可接受度良好的产品。因此,L-阿拉伯糖和木糖是2种较好的还原羰基,可以用于增强鲢鱼肉糜凝胶的质构和香气。     

Color improvement by titanium dioxide and its effect on gelation and texture of proteins recovered from whole fish using isoelectric solubilization/precipitation

Whiteness is a critical attribute for restructured fish products such as surimi seafood. However, the whiteness of gels made from proteins recovered from fish processing by-products or whole fish using isoelectric solubilization/precipitation is poor. The by-products and whole fish contain bones, scales, skin, etc. that affect gel color. Therefore, whiteness needs to be improved if marketable products are to be developed from recovered proteins. The objectives of this study were to determine effects of titanium dioxide (TiO₂) on: (1) color; (2) texture; and (3) viscoelasticity (G′) of gels made from isolated carp proteins and Alaska pollock surimi. Carp proteins were recovered with isoelectric solubilization/precipitation. TiO₂ was added to carp proteins at 0-0.5 g/100 g. TiO₂ was not added to surimi. Due to much higher (P < 0.05) yellowness (b^∗) and lower (P < 0.05) lightness (L^∗), the whiteness of carp gels without TiO₂ was lower (P < 0.05) than surimi gels. TiO₂ at ≥ 0.2 g/100 g resulted in better (P < 0.05) whiteness of carp gels than surimi gels without chalky and artificially white appearance. TiO₂ did not affect texture or viscoelasticity. This research demonstrates that whiteness of restructured fish products based on proteins recovered from whole fish via isoelectric solubilization/precipitation can be similar to the whiteness of surimi seafood.     

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.     

Surimi: The “high tech” raw materials from minced fish flesh

Abstract

Unknown in the United States before 1979, the age‐old Japanese process of preparing gelled fish protein products has excited the world seafood industry. Made from washed minced flesh, surimi is an ideal raw material for analog seafood products (e.g., crab, scallops, shrimp) and other innovative formulated foods. Surimi is a highly functional, pure fish protein‐water‐cryoprotectant combination that, when properly combined with other ingredients, will form a stable gel.

International politics involving the International Fishery Conservation Act, the establishment of fishery conservation zones, and world need for better utilization of raw material from the sea have all contributed to the rapid rise in popularity of surimi products. Surimi, truly the “high tech” product from modernization of the world's fishing industry, can enable us to realize total utilization of this most important source of protein.     

Optimum chopping conditions for Alaska pollock, Pacific whiting, and threadfin bream surimi paste and gel based on rheological and Raman spectroscopic analysis

Rheological and Raman spectroscopic properties of surimi from three species [Alaska pollock (AP) (cold water), Pacific whiting (temperate water), and threadfin bream (warm water)] were investigated as affected by various chopping conditions. Comminuting Alaska pollock surimi at 0 °C demonstrated superior gel hardness and cohesiveness when chopping time was extended to 15-18 min; however, long chopping time at higher temperatures resulted in a significantly decreased gel texture particularly at 20 °C. Warm water fish threadfin bream exhibited higher gel texture when chopping was done longer at higher temperature. Rheological properties were significantly affected by both chopping time and temperature. Species effect, based on their thermal stability, was readily apparent. Raman spectroscopy revealed a significant change in disulfide linkage and the reduction of secondary structure upon extended chopping. Dynamic oscillation rheology demonstrated the damage of light meromyoisn and lowering of onset of gelling temperature as the chopping time was extended. PRACTICAL APPLICATION: Chopping conditions to determine gel quality and manufacture surimi seafood are varied by all manufacturers. This paper covering three primary species for surimi with their suggested optimum chopping conditions: 15 min for Alaska pollock when chopped at 0 °C, 15 min for Pacific whiting at 15-20 °C, and 18 min for threadfin bream at 25-30 °C. The use of optimum chopping condition should maximize the value of each surimi and provide consistent quality to the end users.     

TEXTURAL PROPERTIES AND COLOR CHARACTERISTICS OF RESTRUCTURED BEEF STEAKS WITH SELECTED BINDERS AND NOMEAT ADJUNCTS

Restructured steaks were evaluated using subjective and objective texture and color analyses. Treatments included: intact muscle, restructured steaks with no additives, salt/sodium tripolyphosphate (NaCl/STP), calcium alginate, crude myosin extract (CME) with 0.1% Nad and 0.4% STP [low salt & phosphate (LSP)], CME with 1.0 NaCl and 0.4% STP [high salt & phosphate (HSP)], surimi LSP and surimi HSP. Restructured steaks made from CME (HSP) or surimi (HSP) exhibited superior (P < 0.05) sensory textural evaluation, tensile strength values, cooking loss properties, color and color stability (subjective and objective) when compared to other restructured steaks except CME (LSP) and NaCl/STP (in some parameters). Restructured steaks made with CME or surimi in combination with 1% NaCl and 0.4% STP improved or maintained textural properties as well as color and color stability of restructured steaks.     

超高压对鲤鱼肉糜-MgCl2凝胶特性的影响

为研究超高压对低盐鲤鱼肉糜凝胶品质的影响,本文在低盐条件下（2% NaCl）,探讨了不同压力超高压处理（100~400 MPa）对含有0.3%氯化镁（MgCl₂）鲤鱼肉糜凝胶的蒸煮得率、保水性、色泽、质构、凝胶强度和流变学特性的改善作用。结果表明:适当的压力处理结合MgCl₂可以显著提高鲤鱼肉糜的凝胶品质。当处理压力为200 MPa时,鲤鱼肉糜凝胶的蒸煮得率、保水性、硬度、凝胶强度均达到最大值,分别为93.14%、95.24%、3327.25 g、3277 g。与对照组相比,适当的压力处理可以显著改善鲤鱼肉糜-MgCl₂凝胶的储能模量（G'）,同时对产品的色泽影响较小。因此,超高压结合氯化镁可以改善低盐鲤鱼鱼糜凝胶的品质,为低盐淡水鱼糜制品的开发提供理论依据。     

PHYSICAL PROPERTIES OF FISH PROTEINS COOKED WITH STARCHES OR PROTEIN ADDITIVES UNDER OHMIC HEATING

ABSTRACT

The texture, color and microstructure of surimi seafood gels were investigated to determine the interaction effects of fish proteins with starches or protein additives under ohmic heating, and to compare ohmically cooked gels with conventional water‐bath‐cooked gels. Gel properties were affected by the type of additive, concentration and cooking method. The effect of starch on gel texture was more pronounced at low concentrations. Compared to wheat starch, potato starch seemed to slightly improve gel strength; however, it decreased the gel whiteness. All nonfish protein additives resulted in better or equal textural properties of gels, whereas there was a slightly negative effect for gel color. Fast ohmic‐cooked gels mostly exhibited higher gel strength than conventionally cooked gels.

PRACTICAL APPLICATIONS

There is a discrepancy between current gel preparation (slow heating by water bath) and current practice of crabstick manufacturing (fast heating). The use of data generated from slow cooking gel preparation for the manufacture of fast cooking crabstick does not make sense. This study demonstrates how starch and protein additives behave at ohmic heating which mimics the fast cooking crabstick manufacture.

     

RECOVERY AND UTILIZATION OF PROTEIN DERIVED FROM SURIMI WASH‐WATER

ABSTRACT

Surimi processors are committed to improve utilization of seafood resources, increase productivity and reduce organic matter discharged into the environment. The object of this study was to recover protein from pollock surimi processing wash‐water using membrane filtration and characterize properties of the recovered material. A pilot unit equipped with membrane elements concentrated protein from the surimi wash‐water. Membrane concentrate and control surimi samples were analyzed for proximate composition, lipid oxidation, color, sodium dodecyl sulfate gel electrophoresis, amino acids and minerals. Membrane concentrate, membrane concentrate plus surimi and control surimi were monitored for 180 days of storage at ?20C. The membrane concentrate had significantly higher moisture and lipid, but lower protein content than surimi. As determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis, membrane concentrate proteins displayed a greater amount of lower molar mass molecules compared with surimi. The amino acid profile was comparable to control surimi and the recovered membrane concentrate proteins had similar nutritional values to that of surimi. The results indicate that the addition of 5% membrane concentrate to surimi will not adversely affect the storage at ?20C and that the recovered wash‐water protein could be used to obtain a fish protein ingredient or added back at a low percentage to surimi products.

PRACTICAL APPLICATIONS

In order to increase productivity and improve utilization of seafood resources, surimi processors are looking into alternative technologies to recover proteins and other material from the wastewater. Membrane filtration is a promising option for the concentration of wastewater. This study was conducted to determine the recovery and characterize the material recovered from surimi wash‐water using a commercial membrane filtration unit. It was demonstrated that the recoverable material is nutritionally similar to the final surimi product and that the overall yield can be increased using membrane technology. In addition to the benefit of recovering protein, the membrane filtration can reduce the amount of material in the waste stream.

     

EFFECT OF PACIFIC WHITING WASH WATER PROTEINS ON ALASKA POLLACK SURIMI GELS

The objective of this work was to evaluate the effect of adding insoluble proteins recovered from Pacific whiting surimi wash water (SWW) on the mechanical and functional properties of Alaska pollack surimi gels. Insoluble proteins from Pacific whiting SWW were added at 0 (control), 10, 30 or 50 g/kg into Alaska pollack grade FA surimi. Changes on mechanical properties, expressible water ( EW ) and color attributes were evaluated in pastes and gels. Results obtained showed that texture profile analysis, puncture test and EW parameters increased significantly by increasing the amount of insoluble proteins added. Although slight changes in color attributes were detected, all surimi gels remained in the same color zone. The results obtained suggest that insoluble proteins from Pacific whiting SWW could be used to improve the mechanical properties of Alaska pollack grade FA surimi gels with a minimum effect on color.

PRACTICAL APPLICATIONS

Insoluble proteins recovered from surimi wash water (SWW) of Pacific whiting added at 10–50 g/kg to Alaska pollack surimi showed no adverse effects on their textural properties (hardness, fracturability, springiness and chewiness) and slight changes on color attributes. The results obtained suggest that it is feasible the use of insoluble proteins recovered from SWW of Pacific whiting in Alaska pollack surimi. Therefore, a double target is obtained: the preservation of environment and an increase in the yield of surimi processing without negative effects on texture.     

The effect of egg albumen on the viscoelasticity of crab sticks made from Alaska Pollock and Pacific Whiting surimi

The influence of the amount of egg albumen contained as a gelation agent in crab sticks made from Alaska Pollock or Pacific Whiting surimi on their viscoelastic properties was examined. Dynamic oscillatory and transient tests allowed a variety of parameters to be measured in order to establish the intensity of the interactions in the protein network which characterize the gel strength. This physical property is fundamental for the nominal quality texture and eating quality of surimi and surimi-based seafood analog products (surimi seafood). Three different egg albumen contents around the nominal value (2%) were studied, namely: 1.5, 2 and 2.5%. The viscoelastic gel strength (A_n) and gel strength (S) values obtained in the frequency sweep and creep tests, respectively, were quite consistent. Increasing the protein content of the surimi increased the gel strength of both types of crab sticks (p < 0.05). The optimum egg albumen content was found to be about 1.5% for Alaska Pollock and 2% for Pacific Whiting surimi. Based on these results, the industry could use less albumen in making crab sticks from Alaska Pollock surimi, which surpasses Pacific Whiting surimi in quality.     

Physical Characteristics of Surimi Seafood as Affected By Thermal Processing Conditions

Texture, color and microbiological characteristics of surimi seafood were measured at three processing temperatures (93°, 85°, and 75°C) and various times (0–120 min). The time required to provide a zero aerobic plate count at 93°, 85°, and 75°C was 5,15, and 15 min, respectively. Both thermal processing temperature and time affected whiteness and shear strain of surimi seafood. As the thermal processing temperature and time increased, the shear strain and whiteness decreased. The higher the thermal processing temperature and longer time, the lower were the shear strain and whiteness. Results indicated 15 min at 75° or 85°C were the optimum thermal processing conditions.