Salt Extractable Protein Research Articles

Investigation of cryoprotectants-treated surimi protein deterioration during chilled and frozen storage: Functional properties and kinetic modeling.

The relative cryoprotective effects of flaxseed protein hydrolysate and pectin in comparison with conventional cryoprotectant (sucrose + sorbitol + sodium tripolyphosphates) on stabilization of proteins in surimi of Capoor (Cyprinus carpio) were investigated during freezing (-20°C for 4 months) and chilling storage (4°C for 10 days). Although pectin caused to improve water-holding capacity (27.8%; 4°C and 21.5%; -20°C) on account of highly more inhibitory impact on the ice crystals growth, the protein denaturation may have occurred. It can be related to higher reduction in the amount of salt extractable protein (%) and the immeasurable value of thiol group in surimi formulation containing pectin compared with other cryoprotectants. The results of modeling surimi samples showed that salt extractable protein and sulfhydryl content were in good agreement with the first-order reaction model at -20°C and second-order kinetic model at 4°C. In comparison with other samples, samples treated with flaxseed protein showed the lowest reaction rate constant during chilled and frozen storage. The results confirmed that flaxseed protein with no sweetness and considerable caloric value had a cryoprotective effect similar to sucrose + sorbitol + polyphosphate and even better.

Effect of chitosan coating on the quality characteristics of rohu (Labeo rohita) fillets during chilled storage

The current work was undertaken to examine the effect of chitosan as a natural edible coating on the quality of rohu (Labeo rohita) fillets during 30 days of chilled storage. The fish fillets were treated with different concentrations of chitosan (0.1, 0.25, 0.5 and 1% chitosan) and fish fillet without addition of chitosan was kept as control. Sampling was done initially on the 0th day and thereafter at ten day intervals and were examined periodically for water holding capacity (WHC), water extractable protein (WEP), salt extractable protein (SEP), thiobarbituric acid reactive substances (TBARS), pH, total viable count (TVC), psychrotrophic count (PTC) and sensory characteristics. Findings indicated that chitosan coating aided in retaining the quality and extended the shelf life of rohu fillets during refrigerated storage suggesting the suitability of using chitosan as a bio-preservative to extend the shelf life of chilled stored fish.

Synergistic effects of ultrasound and soluble soybean polysaccharide on frozen surimi from grass carp

Ultrasound and water soluble soybean polysaccharide (SSPS) were applied during the freezing of grass carp surimi. Ultrasound-assisted immersion freezing (UF) process was observed from 0 °C to −15 °C. Based on characteristic freezing time, tempering-stage freezing rate and the quality change of surimi after a 14-day storage period, the optimal sonication was performed 5 times at 300 W, for 10 s, with 40 s intervals. The cryoprotective effects of SSPS content on surimi myofibillar protein were subsequently investigated during 28-day frozen storage at −18 °C. The Ca2+-ATPase activity, total sulphydryl content, active sulphydryl content, salt extractable protein content, whiteness and water-holding capacity of frozen surimi were determined after adding SSPS (0%, 1%, 3% and 5%). The results showed that synergism of SSPS and UF occurred. Consequently 3% SSPS was best for mitigating the protein denaturation during processing.

Effect of cryogenic immersion freezing on quality changes of vacuum-packed bighead carp (Aristichthys nobilis ) during frozen storage

The effect of cryogenic immersion freezing (CIF) on the quality characteristics of bighead carp fillet was investigated during frozen storage and compared with air‐blast freezing (AF). Freezing rate of CIF treated filets was approximately 4.5 times higher than that of AF treated samples. Cryogenically frozen carp fillets showed higher retention (60%) of texture and better integrity of the muscle microstructure than the AF treated samples during the frozen storage. Additionally, a significant inhibition effect (p < .05) on the decrease of salt extractable protein and total SH content, Ca²⁺‐ATPase activity were observed in CIF than AF. Compared with the AF treatment, the CIF technique improved the quality of frozen carp fillets overall and the shelf‐life could be extended to at least 6 months. The findings indicated that cryogenic immersion freezing could be an effective rapid freezing technology for long‐term storage of freshwater fish with better scale‐up feasibility. PRACTICAL APPLICATIONS: Bighead carp fillets were frozen approximately 4.5 times faster by cryogenic cabinet quick freezer than by air‐blast freezer. Cryogenic immersion frozen carp fillets had better overall quality as compared with the samples frozen by air‐blast freezer. Cryogenic immersion freezing could be considered as an effective rapid freezing technology for long‐term storage of freshwater fish with better scale‐up feasibility.

Production and assessment of Pacific hake (Merluccius productus) hydrolysates as cryoprotectants for frozen fish mince

The aim of this study was to investigate application of fish protein hydrolysates (FPHs) as cryoprotectants for cod fish mince subjected to freeze-thaw abuse. Response surface methodology revealed little difference in cryoprotectant ability between FPHs produced from Pacific hake muscle within the range of conditions studied, namely Flavourzyme® enzyme/substrate ratio (E/S 1–4%), time (1–6h) and pH (5–7). When added at 4% or higher concentrations, FPH minimized expressible moisture and cook loss, while maximizing salt extractable protein from freeze-thaw abused fish mince, providing similar or better cryoprotection compared to an 8% sucrose-sorbitol blend, and a stabilizing effect of FPH on myosin was observed by differential scanning calorimetry. Sensory evaluation showed that addition of 8% FPH in fish ball products increased the perception of fishiness, saltiness, bitterness and firmness while decreasing moistness. FPH could be a viable alternative to the sugar-based cryoprotectants currently used for frozen fish products.

The effects of superchilling with modified atmosphere packaging on the physicochemical properties and shelf life of swimming crab.

The objective of the present study was to investigate the effects of superchilling with modified atmosphere packaging on the physicochemical properties and shelf life of swimming crab. As the storage time increased, the rates at which the total aerobic plate count, total volatile basic nitrogen, pH, peroxide value and thiobarbituric acid-reactive substances value increase were significantly lower for the superchilling with modified atmosphere packaging (SCS+MAP) treatment compared to superchilling storage (SCS) and chilling storage (CS). With increasing storage time, the carbonyl content of the proteins increased from 1.21nmol/mg of protein (0day) to 2.03, 1.87, 1.66nmol carbonyl/mg protein on the 6th day for CS, SCS and SCS+MAP, respectively. The disulfide bonds increased in a similar manner, and the total sulfhydryl content, salt extractable protein and Ca-ATPase stability decreased. Sodium dodecyl sulphate polyacrylamide gel elcetrophoresis (SDS-PAGE) and microstructure analysis also indicated that SCS+MAP could reduce the degree of protein degradation. These results suggested that superchilling with modified atmosphere packaging offers an effective approach to slowdown protein and lipid oxidation, and extends the shelf life of swimming crab. However, superchilling with high-CO2 packaging had a negative effect on the surface hydrophobicity and drip loss of swimming crab.

Comparison between the Arrhenius model and the radial basis function neural network (RBFNN) model for predicting quality changes of frozen shrimp (Solenocera melantho)

ABSTRACTChanges in quality indices [total volatile base nitrogen (TVB-N), salt extractable protein (SEP), hypoxanthine (Hx), K-value, sensory assessment (SA), and electrical conductivity (EC)] for shrimp (Solenocera melantho) stored at −28, −20, and −12°C for 112 days were investigated in this study. The Arrhenius model and the radial basis function neural network (RBFNN) model were established to predict changes in the quality of shrimp during storage. Quality of shrimp stored at −12°C changed more quickly during 56–112 days, but those stored at −28°C deteriorated slowly during the entire storage period. Additionally, the indicators SEP, EC, and SA all fitted to the Arrhenius model well (relative errors within ±10%), but this model did not perform well in the prediction of K-value, Hx, and TVB-N on some days. However, the RBFNN model showed excellent accuracy for all indicators (relative errors within ±0.5%). The RBFNN model performed better than the Arrhenius model in predicting the quality of shrimp stored at −28°C to −12°C.

Effects of High Hydrostatic Pressure on the Physical, Microbial, and Chemical Attributes of Oysters (Crassostrea virginica).

The change in the quality attributes (physical, microbial, and chemical) of oysters (Crassostrea virginica) after high hydrostatic pressure (HHP) treatment at 300 MPa at room temperature (RT, 25 °C) 300, 450, and 500 MPa at 0 °C for 2 min and control oysters without treatment were evaluated over 3 wk. The texture and tissue yield percentages of oysters HHP treated at 300 MPa, RT increased significantly (P < 0.05) compared to control. Aerobic and psychrotrophic bacteria in control oysters reached the spoilage point of 7 log CFU/g after 15 d. Coliform counts (log MPN/g) were low during storage with total and fecal coliforms less than 3.5 and 1.0. High pressure treated oysters at 500 MPa at 0 °C were significantly higher (P < 0.05) than oysters HHP treated at 300 MPa at 0 °C in lipid oxidation values. The highest pressure (500 MPa) treatment in this study, significantly (P < 0.05) decreased unsaturated fatty acid percentage compared to control. The glycogen content of control oysters at 3 wk was significantly higher (P < 0.05) when compared to HHP treated oysters [300 MPa, (RT); 450 MPa (0 °C); and 500 MPa (0 °C)]. HHP treatments of oysters were not significantly different in pH, percent salt extractable protein (SEP), and total lipid values compared to control. Based on our results, HHP prolongs the physical, microbial, and chemical quality of oysters.

Effects of ozone on the removal of geosmin and the physicochemical properties of fish meat from bighead carp ( Hypophthalmichthys nobilis )

Two manners of ozone treatment (washing with ozonized water and ozone-flotation) were selected to remove the geosmin in the fish muscle from bighead carp. A total of 42.09%–54.28% and 42.78%–69.19% geosmin in fish muscle could be eliminated by ozone water and ozone-flotation washing for 5–20 min, respectively. Treatment with ozone of an appropriate condition significantly increased the salt-extractable protein, Ca2 +-ATPase activity, total sulfhydryl and active sulfhydryl contents, carbonyl content of the myofibrillar protein, and gel strength without improving PV and TBA values too much. No apparent changes in the protein distribution and no new patterns appeared in SDS-PAGE after the ozone water treatment. The results indicate that ozone water treatment is a prospectively mild oxidation protocol than ozone flotation to enhance the physicochemical properties of fish protein from bighead carp as well as to eliminate muddy flavours. Ozonation has been used for years to disinfect water for drinking purposes in Europe. A number of other commercial uses have been found for ozone including disinfection of bottled water, swimming pools, prevention of fouling of cooling towers, and wastewater treatment. Ozone use may have many advantages in the food industry. There are suggested applications of ozone in the food industry such as food surface hygiene, sanitation of food plant equipment, reuse of waste water, and lowering of the biological oxygen demand (BOD) and chemical oxygen demand (COD) of food plant waste. Ozone is a strong oxidant that also has decolorizing and deodorizing effects, and thus offers many advantages in the food industry, and has been traditionally used in freshwater aquaculture systems in the treatment of fish, disinfection of eggs, sterilization of water to improve the water quality, and decomposition of odorous compounds in natural water in addition to its applications for improving the sensory quality and shelf life of fish. Since 1920, scientists have attempted to exploit the wide-range disinfection characteristics of ozone to slow the decomposition for improving the safety of fishing products. A number of commercial uses have been found for ozone, including the disinfection and preservation of aquatic products. In the United States, ozone received Generally Recognized as Safe (GRAS) classification in 1997, and in 2001, the FDA officially approved ozone for use in the food industry and for direct contact with food products, including fish, meat, and poultry. Ozone has continued to gain momentum in the food processing industry as the safest, most cost-effective, and a chemical-free way of dealing with food safety management.

Quality changes and predictive models of radial basis function neural networks for brined common carp (Cyprinus carpio) fillets during frozen storage

To investigate and predict quality of 2% brined common carp (Cyprinus carpio) fillets during frozen storage, free fatty acids (FFA), salt extractable protein (SEP), total sulfhydryl (SH) content, and Ca2+-ATPase activity were determined at 261K, 253K, and 245K, respectively. There was a dramatic increase (P<0.05) in FFA and a sharp decrease (P<0.05) in SH at 261K during the first 3weeks. SEP decreased to 67.31% after 17weeks at 245K, whereas it took about 7weeks and 13weeks to decrease to the same extent at 261K and 253K, respectively. Ca2+-ATPase activity kept decreasing to 18.28% after 7weeks at 261K. Furthermore, radial basis function neural networks (RBFNNs) were developed to predict quality (FFA, SEP, SH, and Ca2+-ATPase activity) of brined carp fillets during frozen storage with relative errors all within ±5%. Thus, RBFNN is a promising method to predict quality of carp fillets during storage at 245–261K.

Effect of Different Thawing Methods and Multiple Freeze-Thaw Cycles on the Quality of Common Carp (Cyprinus carpio)

The effect of different thawing methods—running water, microwave, slack water (25°C), air (25°C), and refrigerator (4°C)—and multiple freeze-thaw cycles (0, 1, 3, and 5) on the quality of common carp were investigated. Microwave thawing showed the lowest score for sensory assessment and the highest cooking loss (p < 0.05), while 4°C refrigerator thawing showed less thawing loss and cooking loss but required the longest thawing time. Ca2+-ATPase activity and sulfhydryl content of air thawing were lower (p < 0.05), while no significant differences were observed among other thawing methods. Water loss and the thiobarbituric acid reactive substances (TBARS) value increased (p < 0.05) when freeze-thaw cycles increased. The sensory scores and hardness decreased significantly when the freeze-thaw cycles increased (p < 0.05). A significant decrease (p < 0.05) was observed in salt-extractable protein content after five freeze-thaw cycles. Different thawing methods affected the quality of common carp. Frozen common carp subjected to freeze-thaw cycles resulted in accelerated lipid and protein oxidation and caused mechanical damage to muscle tissues.

Effects of Ozone-Induced Oxidation on the Physicochemical Properties of Myofibrillar Proteins Recovered from Bighead Carp (Hypophthalmichthys nobilis)

The effect of oxidation with ozone on myofibrillar proteins from bighead carp (Hypophthalmichthys nobilis) and its influence on the textural properties of surimi gels of bighead carp were investigated. Treatment with ozone of an appropriate concentration significantly increased the salt extractable protein (SEP), Ca2+-ATPase activity, total sulfhydryl and active sulfhydryl contents, surface hydrophobicity, and carbonyl content of the myofibrillar proteins. The breaking force and deformation of the surimi gels of bighead carp initially increased and subsequently decreased as the extent of oxidation increased. Based on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis, there were no apparent changes in the protein distribution and no new patterns appeared in electrophoresis processing analysis after the ozone treatment. Differential scanning calorimetry (DSC) found that low concentrations of ozone water rinse had slight effects on thermal stabilities of myofibrillar proteins, which coincided with the above results. The present study indicates that ozone treatment is a prospectively mild oxidation protocol for enhancing the physicochemical properties of fish proteins from bighead carp.

Quality Changes and Establishment of Predictive Models for Bighead Carp (Aristichthys nobilis) Fillets During Frozen Storage

The objectives of this study were to investigate quality changes of bighead carp fillets during frozen storage by measuring free fatty acids (FFA), salt extractable protein (SEP) content, Ca2+-ATPase activity, and total sulfhydryl (SH) content and to develop predictive models based on them. FFA increased with the extension of storage time. Meanwhile, SEP content, SH content, and Ca2+-ATPase activity all decreased during storage. A marked inhibition (p < 0.05) of FFA formation and SEP content, Ca2+-ATPase activity and SH content decrease was observed during storage of bighead carp fillets at −30 °C, compared to those stored at −10 and −20 °C. Additionally, the relative errors of models based on Ca2+-ATPase and SH were all below 10 %. Thus, the lower frozen temperature can inhibit quality damage effectively, and a reliable estimation of quality changes could be performed by models based on Ca2+-ATPase and SH.

Changes in Texture and Liquid Holding Capacity of Spiced Liquid Smoked Silver Carp (Hypophthalmichthys Molitrix) Muscle Wrapped in Aluminium Foil during Refrigerated Storage

The effects of equivalent concentrations of both garlic and ginger separately in fresh and powder form in muscle proteins of liquid smoked silver carp (Hypophthalmichthys molitrix) during chilled storage were investigated for a period of 24 days. The control and the treated smoked fish samples were analysed periodically for liquid holding capacity, salt extractable protein, texture and sensory quality characteristics. The results showed loss of that liquid holding capacity, salt extractable protein content for all sample (P < 0.05), however more loss observed on ginger treated samples. Force required compressing or shearing the sample as hardness, decreased more in ginger incorporated samples (p < 0.05). Sensory parameters of odour, texture, and appearance for all samples decreased during the chilled storage period (p < 0.05) but were still within acceptable limits, except on texture of fresh ginger samples at day 24. The results obtained from this study suggest that ginger in fresh and powder form, have high negative impacts on texture properties and protein functionality of liquid smoked silver carp muscle stored at 4 ± 1°C.

Research on Proteinous Adhesive Made of Protein Isolated from Crayfish Shell Waste

Defatted crayfish shell waste (CSW) was prepared by the removal of extractable fat with cyclohexane. CSW was pretreated by benzoic acid and demineralized by acids. Proteins in the pretreated CSW were extracted with NaOH and 0-4% NaCl concentrations with 0.05% CaCl2 at pH 5.5-6.6 for 1 h at 50°C. By using the salt extraction procedure, CSW protein concentrate (29 g) was obtained from pretreated CSW (100 g). Recovery of protein was dependent on the extraction temperature employed; recovery values ranged from 33.2 to 51.4%. At 4% NaCl concentration, CaCl2 increased protein solubility by 30%, compared to the control. The adhesiveness of saltextractable protein at various pH values ranging from 5.0 to 9.0 was investigated. At pH 6.0-8.0, adhesiveness of salt-extractable protein showed the highest value (78.2 kg). The adhesiveness increased linearly as the salt-extractable protein concentration increased up to 24% with respect to temperature for salt-extractable protein adhesiveness, the greatest adhesiveness was in the range of 70 to 90. Improved adhesiveness and water resistance were observed with 0.05% glutaraldehyde treatment.

Effects of Bicarbonate, Xanthan Gum, and Preparation Methods on Biochemical, Physicochemical, and Gel Properties of Nile Tilapia (Oreochomis niloticus Linn) Mince

This study was aimed to determine the effects of phosphate compound substitutions (sodium bicarbonate and xanthan gum) and preparation methods—headed, gutted whole fish, and mince; fresh and after frozen storage (−20°C for 3 months)—on Nile tilapia mince qualities. Results showed that bicarbonate (0.3% with 8% sucrose/sorbitol) is an efficient phosphate compound replacement as evidenced by the comparative values of salt extractable protein, Ca2+-ATPase activity, total sulfhydryl content, and textural properties to those of the phosphate-added—0.3% sodium tripolyphosphate (STPP) with 8% sucrose-sorbitol—sample after 3-month frozen storage (p > 0.05). Both cryoprotected samples containing STPP or bicarbonate exhibited higher denaturation temperatures of myosin than others. Xanthan gum (0.5%) could neither stabilize the biochemical and physicochemical properties of mince during 3-month frozen storage nor improve textural properties of gel from frozen whole fish.

Cryoprotective effect of trehalose on washed chicken meat.

The cryoprotective effects of trehalose (w = 0-10%) on washed chicken meat (WCM) were investigated. WCM was produced from broiler, frozen and stored for 360days on -30°C. Myofibrillar protein functional stability was monitored by salt extractable protein (SEP) and differential scanning calorimetry (DSC). Salt extractable protein (SEP) showed that the addition of trehalose caused smaller decrease in protein solubility during frozen storage. Peak thermal transition (T p) and denaturation enthalpy (ΔH) of myofibrillar proteins were evaluated. Differential scanning calorimetry (DSC) revealed a shift in peak thermal transition temperature (T p) of myosin and actin to higher temperature as the mass fraction of trehalose increases. The transitions enthalpies of myosin and actin of WCM samples showed higher increase with the increase of mass fraction of trehalose. Since the value of denaturation enthalpy is directly related to amount of native proteins, higher values of ΔH indicates to the higher cryoprotective effects of trehalose.

Cryoprotective effect of trehalose and maltose on washed and frozen stored beef meat

The cryoprotective effects of trehalose and maltose (w = 2&amp;ndash;10%) on washed beef meat were investigated. Washed beef meat produced from fresh beef meat was frozen and stored for 360 days at &amp;ndash;30&amp;deg;C. Myofibrillar protein functional stability was monitored by salt extractable protein (SEP) and differential scanning calorimetry (DSC). Salt extractable protein (SEP) showed that the addition of trehalose and maltose causeda smaller loss of protein solubility during the frozen storage. Peak thermal transition (T&lt;sub&gt;p&lt;/sub&gt;) and denaturation enthalpy (&amp;Delta;H) of myofibrillar proteins were evaluated. Differential scanning calorimetry (DSC) revealed a shift in the peak thermal transition temperature (T&lt;sub&gt;p&lt;/sub&gt;) of myosin and actin to higher temperature as the mass fractions of trehalose and maltose increased. The transitions enthalpies of myosin and actin of the washed beef meat samples showed a higher increase with the increase of mass fraction of trehalose then of that of maltose. Since the value of denaturation enthalpy is directly related to the amount of native proteins, higher values of &amp;Delta;H point to higher cryoprotective effects of trehalose.

Gelation Properties of Spent Duck Meat Surimi‐Like Material Produced Using Acid–Alkaline Solubilization Methods

The gelation properties of spent duck meat surimi-like material produced using acid solubilization (ACS) or alkaline solubilization (ALS) were studied and compared with conventionally processed (CON) surimi-like material. The ACS process yielded the highest protein recovery (P < 0.05). The ALS process generated the highest lipid reduction, and the CON process yielded the lowest reduction (P < 0.05). Surimi-like material produced by the CON process had the highest gel strength, salt extractable protein (SEP), and water holding capacity (WHC), followed by materials produced via the ALS and ACS processes and untreated duck meat (P < 0.05). The material produced by the CON process also had the highest cohesiveness, hardness, and gumminess values and the lowest springiness value. Material produced by the ACS and ALS processes had higher whiteness values than untreated duck meat gels and gels produced by the CON method (P < 0.05). Surimi-like material produced using the ACS and CON processes had significantly higher myoglobin removal (P < 0.05) than that produced by the ALS method and untreated duck meat. Among all surimi-like materials, the highest Ca(2+)-ATPase activity was found in conventionally produced gels (P < 0.05). This suggests that protein oxidation was induced by acid-alkaline solubilization. The gels produced by ALS had a significantly lower (P < 0.05) total SH content than the other samples. This result showed that the acid-alkaline solubilization clearly improved gelation and color properties of spent duck and possibly applied for other high fat raw material.

CHANGES IN SALT EXTRACTABLE PROTEIN AND CA2+‐ATPASE ACTIVITY OF MINCE FROM SILVER CARP (HYPOPHTHALMICHTHYS MOLLITRIX) DURING FROZEN STORAGE: A KINETIC STUDY

ABSTRACT Changes in salt extractable protein (SEP) and Ca2 + ‐ATPase activity of actomyosin from washed and unwashed silver carp stored at −10 and −20C were investigated. The resultant decrease of SEP and Ca2 + ‐ATPase activity mainly occurred in the first 5 and 7 weeks, and the changes obeyed first‐order model. The kinetic models of SEP and Ca2 + ‐ATPase changes were established during frozen storage. The rate constant k of decline in SEP and Ca2+‐ATPase activity of samples stored at −10C were higher than that of samples stored at −20C; the D value of samples stored at −10C were lower than that of samples stored at −20C. Compared with washed samples, unwashed samples had a higher rate constant k and activation energies E, and a lower D value. Activation energies E of SEP were higher than E of Ca2+‐ATPase activity in all samples.PRACTICAL APPLICATIONSSilver carp is one of the main freshwater fish species in China. Washing is an important step for fish processing and temperature is an important factor on fish protein storage. The changes of the kinetic models of SEP and Ca2+‐ATPase during frozen storage can explain the effect of temperature and time on silver carp mince quality. These kinetic models can be used to predict the silver carp protein functional changes during frozen storage, and help to provide better methods to effectively utilize silver carp protein resource.