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).     

Gelation of Surimi by High Hydrostatic Pressure

The effects of high hydrostatic pressure (HHP) on gel strength of Pacific whiting and Alaska pollock surimi were determined by torsion. Pacific whiting gels were made with and without 1% beef plasma protein (BPP) as protease inhibitor. HHP treated whiting (1% BPP added) and pollock gels showed greatly increased strain values at all pressure/temperature combinations compared with heat-set controls. Stress values for the same samples were variable depending on treatment and species. A three-fold increase in strain and stress was found for HHP treated whiting gels made without inhibitor.     

Surimi Gel Colors as Affected by Moisture Content and Physical Conditions

Colors (CIE L*, a*, and b*) of Alaska pollock (7′heragra chalcogramma) and Pacific whiting (Mecs productus) surimi gels were evaluated and related to compositional and physical conditions during preparation and measurements. Ten samples were used in each treatment. Water addition, sample size, species, cooking and test temperatures, and freeze/thaw affected lightness (L*) and yellowness (b*) values, while outside light conditions at measurement did not affect colors. Greenness (-a*) values were less affected by all conditions.     

Linear Programming in Blending Various Components of Surimi Seafood

Shear stress, shear strain, whiteness of surimi gels made with high and low grades of Alaska pollock and Pacific whiting were investigated to determine linearity of their relationships. A canonical form of least square linear model in mixture design showed a greater linearity (r²0.99) for blending high and low grade surimi lots. Due to linearity without interaction (p<0.001), a least cost linear program provided optimum blending for surimi lots based on value, constraints, and decision variables. Linear programming to determine optimum formulation of surimi with starches and water content was not feasible due to interactions between surimi and starch, or starch and water.     

Functional Properties and Shelf Life of Fresh Surimi from Pacific Whiting

Total aerobic plate count (APC), shear stress, shear strain, and color of fresh Pacific whiting surimi stored at 5°C were determined at day 0, 1, 3, 5, and 7. Frozen surimi was prepared with four levels of cryoprotectams (0, 3, 6, and 9%) and was compared with fresh surimi for gelforming ability. Fresh Pacific whiting surimi had a shelf life of 5 days. The gel functionality remained unchanged throughout the storage time. Strain values of fresh surimi were not different from those of frozen surimi with 9% cryoprotectants, but stress values of fresh surimi were almost three times higher than those of frozen surimi.     

Gel Properties of Surimi from Various Fish Species as Affected by Moisture Content

Torsion, punch, and color tests as affected by moisture content were evaluated for surimi from pollock, Pacific herring, arrowtooth flounder, and Pacific whiting. Torsion stress and strain decreased linearly with increased moisture content but strain values were less sensitive to moisture than were stress values. This finding enabled mathematical normalization of torsion stress and strain values rather than adjusting the moisture content of samples prior to testing. Punch test results, while linearly related to moisture content, were not as consistent as torsion test results. The L* and whiteness increased with higher moisture content, but changes in a* and b* values were not consistent for surimi from different species.     

Rheological and Textural Properties of Pacific Whiting Surimi Gels As Influenced by Chicken Plasma

Rheological properties of Pacific whiting surimi, in the absence and presence of chicken plasma (CP) at different levels (0.3–3.0%, w/w), were studied by dynamic rheological (small strain) and torsion fracture measurements, respectively. The surimi paste exhibited two major distinctive rheological transitions during heating (1°C/min) from 20 to 90°C with peaks observed at 33 and 56°C. The abrupt loss of G′ upon heating from 47 to 57°C, and the occurrence of small peak of phase angle at the same temperature range were prevented by the addition of CP. Nevertheless, the final G′ of the surimi paste added with CP was lower than that of the control. But shear fracture stress of both kamaboko and modori gels increased as the CP levels increased and shear strain increased with the addition of CP up to 2% (P < 0.05). CP inhibited the degradation of myosin heavy chains (MHC) caused by endogenous proteinases as indicated by more retained MHC and lowered TCA-soluble peptide content. Whiteness of gels decreased somewhat with increasing CP levels. CP, thus, could be a helpful additive for improving gelling properties of Pacific whiting surimi     

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.     

Surimi–alginate gels as affected by setting: a study based on mixture design and regression models

Interaction and setting effects on surimi–alginate gels were investigated by d-optional mixture design and analyzed by linear and nonlinear manual or stepwise regression models. Nonlinear model showed significant interactions of surimi–water on water retention ability (WRA) and failure shear stress, and surimi–alginate on whiteness of control (non-set) surimi–alginate gels. But no interaction was found on shear strain of control gels. In set gels, only WRA fitted nonlinear model with interaction terms for surimi–water and alginate–water. Setting increased the gel functionalities such as WRA, whiteness, and shear stress of surimi–alginate gels. The response trace plots showed that WRAs and failure shear stresses of both control and set gels of surimi–alginate were increased by alginate and surimi contents, but decreased by water. However, whiteness was increased by water and surimi contents, but decreased by alginate, while shear strain was increased by surimi content, but decreased by alginate and water.     

Characterization of Thermorheological Behavior of Alaska Pollock and Pacific Whiting Surimi

ABSTRACT: Thermorheological behavior of Alaska pollock (AP) and Pacific whiting (PW) surimi was evaluated during gelation at different moisture contents (80% to 95%). The temperature sweep data (storage modulus, G', compared with temperature) for both surimi clearly indicated G' minima. Unlike for the PW surimi, the minimum values of the AP surimi was moisture-content dependent and there was a linear relationship between logarithm of concentration and reciprocal absolute temperature at gelation. The activation energy ( Ea ) for aggregation after gelation temperature at each moisture content was calculated by a nonisothermal kinetic model for both AP and PW Surimi. The Ea values increased with moisture content of the system and ranged from 172.8 to 232.9 kJ/mol. Based on the assumption that melting temperature for a thermo-reversible gel may be considered equivalent to gelation temperature for thermo-irreversible gels, an Arrhenius-type model was used to estimate the enthalpy of cross-links formation for AP surimi to be 300.3 kJ/mol.     

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.     

Functional Protein Additives in Surimi Gels

Medium-grade Alaska pollock surimi was used to investigate the effects of functional protein additives on texture and colors. Torsion failure and differential scanning calorimetry tests were applied to measure gel strength, gel deformability, and calorimetric properties. CIE Lab color values were also measured. Shear stress values of gels and peak temperature of DSC thermograms were all increased. Shear strain, a good indicator of protein-protein interaction, was increased only by addition of egg white and beef plasma protein. Yellowness (b*) values were affected by all additives except frozen egg white. Whiteness index (L*-3b*) was a more effective indicator to differentiate additives.     

TEXTURE DEGRADATION KINETICS OF GELS MADE FROM PACIFIC WHITING SURIMI

Degradation kinetics of whiting surimi gel texture were examined over a temperature/time range (40–85C, 0.5–35 min). Changes in textural properties of whiting surimi gel were mainly affected by proteolytic activity of endogenous proteinase. A decrease of failure shear stress and shear strain followed first order kinetics. The kinetic parameters developed using either isothermal or nonisothermal principles were similar. Degradation rate of gel texture increased with temperature, reaching a maximum at 55C. It then decreased to a minimum at 70C. E_a values for the activation and inactivation temperature range were 138.6–162.6 and 13.5–35.0 kJ/mol, respectively.     

Degradation Kinetics of Myosin Heavy Chain of Pacific Whiting Surimi

Pacific whiting surimi paste was ohmically heated to investigate degradation of myosin heavy chain (MHC) caused by endogenous proteinase over a range of 40–85°C and 0.5–35 min. Degradation was best described with an apparent reaction order of 1.4. Changes of degradation rate increased with temperature and reached a maximum at 57°C. Then, rate of MHC degradation decreased with higher temperature and reached a minimum at 75°C. E_a values of activation and inactivation zone were 142.3 and 83.1 kJ/mol, respectively. Generally, failure shear stress and shear strain increased linearly with MHC content. Proteolytic degradation of actin exhibited the same trend as that of MHC but at a slower rate. The synergistic effect of actin in the gelation of whiting surimi was predominant at ≥75°C.     

Ohmic Heating Maximizes Gel Functionality of Pacific Whiting Surimi

Surimi without enzyme inhibitors containing 78% moisture and 2% NaCl was heated conventionally and ohmically to 90°C after holding at 55°C for 0, 1, 3 and 5 min. Gels heated slowly in a water bath exhibited poor gel quality, while the ohmically heated gels without holding at 55°C showed more than a twofold increase in shear stress and shear strain over conventionally heated gels. Degradation of myosin and actin was minimized by ohmic heating, resulting in a continuous network structure. Ohmic heating with a rapid heating rate was an effective method for maximizing gel functionality of Pacific whiting surimi without enzyme inhibitors.     

Effect of Various Types of Egg White on Characteristics and Gelation of Fish Myofibrillar Proteins

ABSTRACT:  Three types of egg white protein (regular dried egg white [REW], special dried egg white [SEW], and liquid egg white [LEW]) were compared for their effect in surimi (CON), containing no egg white (EW). They were characterized for enzyme inhibition and time of EW addition, either with cryoprotectants prior to freezing or during gel preparation, using Pacific whiting surimi. In addition, the setting (suwari) effect and fish protein–EW protein interactions (dynamic rheological properties, total sulfhydryl groups, and fracture gel analysis) were evaluated using Alaska pollock surimi. After 12 mo frozen storage, adding 2% and 3% SEW to Pacific whiting surimi during chopping significantly ( P  < 0.05) increased the force and deformation values compared to adding the respective EW before freezing. The highest ( P  < 0.05) force (175.2 g) and deformation (9.0 mm) values after 12 mo were obtained when 3% SEW was added during chopping. Enzyme autolysis showed that addition of 2% EW protein was effective at inhibiting enzyme activity. During setting, adding 2% SEW maintained force (1047.4 g) and deformation (17.9 mm) values similar ( P  > 0.05) to CON (1055.1 g; 19.3 mm) and significantly ( P  < 0.05) better than 2% REW (666.1 g; 15.6 mm). Texture results corresponded well to other data where 2% SEW showed the lowest total sulfhydryl groups (48.3 mole/10⁵ g), and higher elastic modulus (G'), which suggests improved protein interaction for gel formation. Overall, the addition of 2% to 3% SEW improved gel textural properties of Pacific whiting and Alaska pollock fish protein.     

Functional properties of proteins recovered from silver carp (Hypophthalmichthys molitrix) by isoelectric solubilization/precipitation

Isoelectric solubilization/precipitation at acidic and basic pH ranges was applied to whole gutted silver carp (Hypophthalmichthys molitrix) in order to recover muscle proteins. Thermal denaturation (T_onset, T_max, and ΔH), viscoelasticity (G′), and texture properties (shear stress) of proteins recovered from carp as affected by functional additives (beef plasma protein, potato starch, exogenous transglutaminase, polyphosphate, and titanium dioxide) were determined and compared to Alaska pollock surimi. Proteins recovered from carp showed typical endothermic transitions only when functional additives were used. Similar to endothermic transitions, viscoelasticity in carp proteins increased only when the additives were used. Typical endothermic peaks and viscoelasticity increase were recorded for Alaska pollock surimi. Carp protein-based gels with functional additives had lower (P < 0.05) shear stress than their surimi counterparts, but greater (P < 0.05) or similar (P > 0.05) when compared to surimi gels without functional additives. In addition, generally higher shear stress was measured for carp protein-based gels developed from basic pH treatments than the acidic counterparts. The present study indicates that proteins can be recovered from whole gutted carp using isoelectric solubilization/precipitation. However, if the recovered proteins are used for subsequent development of restructured food products, functional additives should be used.     

Gel Properties of Surimi from Pacific Herring

Surimi produced from male Pacific herring (Clupea harengus pallusi), a by-product of the roe fishery, formed gels comparable to those formed by lower-grade pollock surimi but were darker in color. Linear relationships were found between moisture content of surimi and punch force, torsion stress, torsion strain, and compression force at failure. Addition of dried beef plasma, egg white, whey protein, wheat gluten or potato inhibitor resulted in stronger gels, although no proteolysis was detected in a control sample. Low-temperature setting, or heating at 40°C prior to cooking at 90°C resulted in stronger gels, as measured by punch test.     

The properties of surimi and kamaboko gels from nine British species of fish

This paper describes the preparation and properties of surimi and derived kamaboko gels from a range of British-caught species of teleost (or bony) fish including white fish (fillets, trimmings and skeletons), fatty fish and an elasmobranch (or cartilaginous) fish. The data include yields, moisture and fat contents, water-binding capacities, pH values and Hunter L,a,b colour values as well as sensory and instrumentally measured indices of texture.
Cod, haddock and whiting fillets and trimmings of haddock and whiting yielded surimi and derived gels with functional properties most closely approaching those of the Alaska pollack surimi used as a standard. Saithe gave a gel which was firm and elastic but which had a low water-binding capacity and was dark in colour. The fatty fish yielded surimi with some potentially useful functional properties but colour and water-binding capacity were inferior to pollack surimi.     

Transglutaminase Effects on Low Temperature Gelation of Fish Protein Sols

Myosin polymerization and formation of ?-(γ-glutamyl)lysine linkages were quantified in Alaska pollock surimi gels which contained no additive (control), or a commercial microbial transglutaminase (MTGase). As preincubation (“setting”) time at 25°C was increased, the gel strength of control and 0.2% MTGase-added samples increased, with greater increases at higher MTGase levels. SDS-PAGE and HPLC analyses showed increasing nondisulfide polymerization and ?-(γ-glutamyl)lysine dipeptide content, with increasing setting time and/or added MTGase. Content of ?-(γ-glutamyl)lysine dipeptide correlated with gel strength (shear stress) and shear modulus at failure (G_f) for these gels. Higher stresses were measured in samples containing 0.2% MTGase than in controls at corresponding levels of ?-(γ-glutamyl)lysine dipeptide, indicating that rate of myosin polymerization may affect ultimate gel strength.