Gel Properties Of Myofibrillar Protein Research Articles

Structural characteristics of Sheldrake meat and secondary structure of myofibrillar protein: effects of oxidation

ABSTRACTThe present study aimed to investigate the effects of oxidation on physicochemical properties of Sheldrake meat and secondary structure of myofibrillar proteins. Sheldrake breast meat was treated with hydroxyl radical generating systems containing different hydrogen peroxide (H2O2) concentrations. Upon oxidation, the water-holding capacity of Sheldrake meat decreased while toughness increased. Myofibrillar proteins were extracted from the non-oxidized and oxidized meat and heat-treated to form myofibrillar protein gels. It was found that 2-thiobarbituric acid (TBARS), protein carbonyl content, and disulfide bond values increased with H2O2 concentration. Raman spectroscopy analysis of the myofibrillar protein gels showed that oxidation led to protein unfolding, decreased α-helix structure, and increased β-sheets, β-turns, and random coils structures. Changes in the secondary structures of proteins affected the water-holding capacity and textural properties of myofibrillar protein gels. Water-holding capacity of the myofibrillar protein gels decreased with H2O2 concentration. Oxidized myofibrillar protein gels showed reduced hardness, springiness, and cohesiveness.

Effects of Red Bean (Vigna angularis) Protein Isolates on Rheological Properties of Microbial Transglutaminase Mediated Pork Myofibrillar Protein Gels as Affected by Fractioning and Preheat Treatment.

Fractioning and/or preheating treatment on the rheological properties of myofibrillar protein (MP) gels induced by microbial transglutaminase (MTG) has been reported that they may improve the functional properties. However, the optimum condition was varied depending on the experimental factors. This study was to evaluate the effect of red bean protein isolate (RBPI) on the rheological properties of MP gels mediated by MTG as affected by modifications (fractioning: 7S-globulin of RBPI and/or preheat treatment (pre-heating; 95℃/30 min): pre-heating RBPI or pre-heating/7S-globulin). Cooking yields (CY, %) of MP gels was increased with RBPI (p<0.05), while 7S-globulin decreased the effect of RBPI (p<0.05); however, preheating treatments did not affect the CY (p>0.05). Gel strength of MP was decreased when RBPI or 7S-globulin added, while preheat treatments compensated for the negative effects of those in MP. This effect was entirely reversed by MTG treatment. Although the major band of RBPI disappeared, the preheated 7S globulin band was remained. In scanning electron microscopic (SEM) technique, the appearance of more cross-linked structures were observed when RBPI was prepared with preheating at 95℃ to improve the protein-protein interaction during gel setting of MP mixtures. Thus, the effects of RBPI and 7S-globulin as a substrate, and water and meat binder for MTG-mediated MP gels were confirmed to improve the rheological properties. However, preheat treatment of RBPI should be optimized.

Physicochemical and Gel Properties of Myofibrillar Protein from Sin Croaker (Johnius dussumieri) Fish During Ice Storage

ABSTRACTThe physicochemical and gel properties of myofibrillar protein (MFP) from sin croaker fish were studied during ice storage for 18 days. Significant changes in the trends of solubility, Ca2+ ATPase enzyme activity, surface hydrophobicity, and water holding capacity of extracted MFP were observed by the 6th day of storage. The Ca2+ ATPase enzyme activity reduced significantly (p < 0.05) by the 6th day of storage. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) did not show a remarkable change in the concentration of myosin heavy chain. Surface hydrophobicity increased almost four times from its original value of 18.98 µg; whereas, water holding capacity showed a fluctuating trend during storage. The emulsion capacity of the MFP was in the range of 0.89- to 1.92-mL oil/mg protein during storage. The gel strength value (313.45 g.cm) of heat-induced gel prepared from fresh minced meat decreased significantly (p < 0.05) by the 6th day of ice storage. Texture profile analysis revealed that changes in hardness and gumminess were concurrent to steeply reducing breaking force up to the 6th day. The histological observation showed gradually increasing gaps between muscle fibers. The histological observations and physicochemical quality indicated that the sin croaker fish can be used for producing good quality surimi when stored for up to 6 days in ice.

Influence of Linoleic Acid-Induced Oxidative Modification on Gel Properties of Myofibrillar Protein from Silver Carp (Hypophthalmichthys molitrix) Muscle

Oxidation extent of myofibrillar protein (MP) from silver carp (Hypophthalmichthys molitrix) was affected by the content and type of lipid peroxidation (LPO) products. Oxidized linoleic acid (OLA) was selected as a main representative of lipid peroxidation to investigate the effects of oxidative modification of LPO products on MP structure. Structural changes of the oxidized myofibrillar protein were evaluated by the contents of carbonyl and total sulfhydryls, surface hydrophobicity, SDS-PAGE and Fourier transform infrared spectroscopy. Heating procedure was also applied for further evaluation of gelling properties. The results from SDS-PAGE indicated that aggregation and denaturation of myosin occurred in the oxidized system. The presence of OLA intensified oxidation-initiated loss of a-helix conformation as well as tertiary structure of MP. With the addition of OLA concentration less than 3 mM, a remarkably enhanced gelling capacity of MP was observed. While the excessive covalent bond (OLA > 5 mM) could lead to the breakage of protein-protein bonds, causing the collapse of the gel structure. The gelation procedure induced by OLA involved simultaneous protein oxidation and internal cross-linking.

Effect of High Intensity Ultrasound on the Gel and Structural Properties ofCtenopharyngodon idellusMyofibrillar Protein

Effect of ultrasound (US) treatment at 0–800 W on the gel properties of Ctenopharyngodon idellus myofibrillar protein (MP) was first evaluated by analyzing the textural properties, water-holding capacity (WHC) and whiteness. Particle size, fluorescence spectra, free sulfhydryl (SH) groups and microstructure were measured to investigate the structure changes. The MP gel treated with US at 600 W gave the best gel properties, including the highest gel strength, hardness, gumminess, chewiness, WHC and whiteness. Compared with untreated gel, the gel network structure of MP gel treated by US was also more denser and uniform. The reduced particle size, narrowed particle distribution, decreased free SH content and intrinsic fluorescence, as well as improved surface hydrophobicity caused by US treatment indicated the unfolding and disaggragation of MP, which could also be the possible mechanism of improved gel properties. Practical Applications The gelation characteristics of myofibrillar protein (MP) are largely responsible for the textural and functional properties of fish products, and are especially important for the quality of surimi. The poor gel properties of Ctenopharyngodon idellus MP largely limited its application in food industry. This research found that high intensity US at 200–800 W, especially at 600 W, could greatly improve the gel properties of C. idellus MP, which can provide a promising alternative to modify the gel properties of MP, and promote the application of C. idellus MP in food industry.

Evaluation of red bean protein [Vigna angularis] isolate on rheological properties of pork myofibrillar protein gels induced by microbial transglutaminase

SummaryThe effects of 1% red bean protein isolate (RBPI) on the gel properties of myofibrillar protein (MP) in various levels of microbial transglutaminase (MTG: 0%, 0.1%, 0.5%, &amp; 1%) were evaluated. The cooking yield (CY) of the MP gels decreased with increasing MTG level, while the addition of RBPI improved the CY of the MP gels. Gel strength (GS) was also improved when RBPI was incorporated into the MP gels containing higher than 0.5% of MTG. The addition of MTG and RBPI was slightly changed the endothermic peak temperatures. Scanning electron microscopy (SEM) showed that the three‐dimensional structure of MP with RBPI alone or in combined with MTG was compacted as compared to the control. Based on the results, RBPI could be functioned as a substrate for MTG (0.5–1.0%) and a water binder of meat protein gel mediated by MTG.

Effects of Oxidation on Water Distribution and Physicochemical Properties of Porcine Myofibrillar Protein Gel

The effects of hydroxyl radicals induced oxidation on water distribution of porcine myofibrillar protein (MP) gels were investigated using nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI), and relationship between MP gel properties and water distribution was analyzed with Pearson’s correlation. Results of NMR spin-spin relaxation time (T2) and MRI suggested that, comparing with unoxidized MP gel, the population of immobile water of gel (P22) decreased by 18.81 %, while that of free water (P23) increased by 85.56 %, and grey scale value decreased by 18.52 %, after being oxidized with 20 mM H2O2, respectively. Images of scanning electron microscope (SEM) showed the highest degree of oxidation led to the most coarse and porous gel-network. Gel properties including WHC, whiteness and strength of MP gels decreased by 14.65 %, 2.83 % and 52.74 % after being oxidized with 20 mM H2O2 (p < 0.05), respectively. Pearson’s correlation analysis showed oxidation, gel-properties and NMR results were highly correlated (p < 0.05). Therefore, we hypothesized that hydroxyl radicals induced oxidation resulted in immobile water shifting to free water partly, thus reduced the abundance of water and gel properties of gels.

Effects and mechanism of modified starches on the gel properties of myofibrillar protein from grass carp

The effects and mechanism of cassava starch (CS), hydroxypropylated cassava starch (HCS) and cross-linked hydroxypropylated cassava starch (CHCS), on gel properties of myofibrillar protein (MP) from grass carp were investigated using texture analyzer, dynamic rheometer, scanning electron microscopy (SEM) and circular dichroism (CD). Water holding capacity (WHC) of MP gels increased from 70% to ca. 90% with an increase in additive amount of modified starches (MS) and HCS improved WHC most effectively. The MS (HCS and CS) at proper additive amount (1.5wt%) improved the textural properties of MP gels significantly (P<0.05). In rheological test, all MS-MP solutions showed viscoelastic nature of MP, but adding MS resulted in much higher G′, suggesting the effect of MS (especially 2.5wt% CHCS) was considerable and equal to increasing protein concentration. The SEM photographs showed the MP gel with 2.5wt% CHCS or 0.5wt% HCS formed compact and homogeneous network, while the gel with CS agglomerated and the agglomerate phenomenon occurred more obviously with increasing additive amount. The addition of MS, especially CHCS, promoted the heat–induced conformational transition from the α-helix companied with β-turn to β-sheet, leading to the MP molecules stretching out.

Effects of fish sarcoplasmic proteins on the properties of myofibrillar protein gels mediated by microbial transglutaminase

Fish sarcoplasmic protein (SP) was extracted and lyophilized to obtain the SP powder. Fish myofibrillar protein (MP) was mixed with SP powder (0, 0.1, 0.5, and 1.0 g/100 g) in 1.8 and 2.6 g/100 g NaCl in the presence of 0.5 g/100 g microbial transglutaminase (MTG) at 4 °C for 6 h. Shear stress of MP mixture decreased with increasing SP concentrations. High thermal stability of MP mixture, assessed by differential scanning calorimetry, at either 1.8 or 2.6 g/100 g NaCl, was observed when SP (1 g/100 g) was added. The myosin heavy chain partially disappeared, suggesting the formation of cross-linked proteins. The gel strength of MP was not affected by the addition of 0.1 g/100 g SP (P > 0.05) whereas it started to decrease when SP was added up to 0.5 g/100 g, regardless of the NaCl concentration. The cooking loss of the MP gel was reduced efficiently when SP was added, even at a low concentration (0.1 g/100 g). A further reduction of cooking loss was observed when SP concentration was increased. The smooth microstructure of the gel surface was observed in samples containing SP, showing the lower cooking loss of fish myofibrillar protein gel.

Effects of Transgluninase and GDL on Gel Properties of Chicken Myofibrillar Proteins

Myofibrillar protein gel properties were studied. Based on which Box-Benhnken center-united experiment was designed for optimization of ratio scheme for gelation strength. The optimum conditions for best gel strength were found to the transgluninase 0.37% of myofibrillar proteins, GDL 1.19%, in 0.88mol/L NaCl concentration at pH 5.96 to form 40mg/ml protein concentration solution. The gel strength was 316.953g. The study showed that transgluninase and GDL could interact significantly in improving gel strength (P &lt;0.01).

Hydroxyl Radical and Ferryl‐Generating Systems Promote Gel Network Formation of Myofibrillar Protein

The objective of the study was to examine how oxidatively induced protein cross-linking would influence the gelation properties of myofibrillar protein (MP) under meat processing conditions. MP suspensions in 0.6 M NaCl at pH 6 were treated with an iron-catalyzed oxidizing system (IOS: 10 microM FeCl(3), 0.1 mM ascorbic acid, 0.05 to 5 mM H(2)O(2)) or a H(2)O(2)-activated metmyoglobin oxidizing system (MOS: 0.01 to 0.1 mM metmyoglobin/H(2)O(2)) that produced hydroxyl radical and ferryl species, respectively. Both oxidizing systems promoted MP thermal gelation, which was evidenced by rapid protein-protein interaction and the enhancement in storage modulus (elasticity) of the gel network as revealed by dynamic rheological testing in the 20 to 74 degrees C temperature range. This gelation-enhancing effect was attributed to the shift of myosin aggregation in the early stage of heating from predominantly head-head association (nonoxidized control samples) to prevalently tail-tail cross-linking through disulfide bonds. However, both hardness and water-holding capacity of chilled gels tended to decline when MP was exposed to >or=1 mM H(2)O(2) in IOS and to all concentrations of metmyoglobin in MOS. Microscopic examination confirmed a more porous structure in oxidized gels when compared with nonoxidized protein gels. The results demonstrated that mild oxidation altered the mode of myosin aggregation in favor of an elastic gel network formation, but it did not improve or had a negative effect on water-binding properties of MP gels. Mild oxidation promotes protein network formation and enhances gelation of myofibrillar protein under normal salt and pH conditions used in meat processing. This oxidative effect, which involves disulfide linkages, is somewhat similar to that in bakery product processing where oxidants are used to improve dough performance through gluten protein interaction.