Gel-forming Ability Research Articles

Biochemical susceptibility of myosin in chicken myofibrils subjected to hydroxyl radical oxidizing systems.

Biochemical changes of myosin in chicken myofibrils exposed to nonenzymatic, hydroxyl radical generation systems (HRGS) were investigated by means of cross-linking reaction, ATPase activity, salt solubility, and 40% saturated ammonium sulfate (AS) extractability. HRGS treatment of myofibrils caused cross-linking of myosin heavy chains (MHC) via disulfide bonding, an increase in Ca-ATPase activity, and a decrease in K-ATPase activity, suggesting that thiol groups of myosin including those at the active site were modified. The specific changes depended on the concentrations of H(2)O(2) in HRGS as well as the weight ratio of H(2)O(2) to myofibrils. On the other hand, the decrease in salt solubility or AS extractability of myosin in HRGS-treated samples proceeded slowly when compared with the cross-linking reaction of MHC, indicating that considerable amounts of myosin biopolymers remained hydrophilic in the ionic solutions. The results demonstrated that initial cross-linking of MHC occurred inside the myosin molecule, and this was followed by progressive aggregation of myosin molecules through intermolecular cross-linking. Oxidation under the current experimental condition decreased the gel-forming ability of myofibrillar proteins, which coincided with the progress of the intra- and intermolecular cross-linking reactions as well as with ATPase activity changes.

Identification of specific oxidatively modified proteins in chicken muscles using a combined immunologic and proteomic approach.

Muscle proteins are generally believed to be key players in free radical processes that eventually lead to oxidative deterioration or modifications of meat proteins resulting in alterations in functionality, for example, gel-forming ability, emulsification properties, and water-binding capacity. This study addresses protein oxidation in chicken muscles using a combined immunologic and proteomic approach and identifies specific proteins that contain carbonyls and/or 3-nitrotyrosine (3-NT). Whereas alpha-enolase was the predominant carbonyl-reactive species among the water-soluble muscle proteins, several other proteins (actin, heat shock protein 70, and creatine kinase) contained carbonyls and/or 3-nitrotyrosine. Finally, this approach was used to demonstrate differential susceptibility of water-soluble muscle proteins toward oxidation in chickens fed a low-antioxidant diet compared with chickens fed a diet supplemented with antioxidant-rich fruits/vegetables.

Inhibition of autolytic activity of lizardfish surimi by proteinase inhibitors

Optimum autolytic activities of lizardfish ( Saurida tumbil) mince and surimi were at pH 6 and 7, respectively, with optimum temperature at 65 °C. Autolysis of surimi was mainly inhibited by phenylmethanesulfonyl fluoride and p-tosyl- l-phenylalanyl-chloromethylketone, indicating the involvement of myofibrillar-associated serine proteinase. Myosin heavy chain (MHC) and tropomyosin were preferentially hydrolyzed, resulting in poor textural properties. Based on TCA-soluble oligopeptide assay, egg white powder (EW) and whey protein concentrate (WPC) showed 77% and 96% inhibition, respectively. However, a significant loss of MHC was found. At any pre-incubation condition (25 °C/4 h, 40 °C/1 h and 65 °C/1 h), EW improved gel-forming ability of lizardfish surimi to a greater extent than WPC. Addition of 1% EW and pre-incubation at 25 °C resulted in an increase of higher molecular weight cross-linked proteins, corresponding to a twofold increase in the breaking force.

Preparation of a gel-forming ointment base applicable to the recovery stage of bedsore and clinical evaluation of a treatment method with different ointment bases suitable to each stage of bedsore

An ointment base for better treatment of bedsores was developed to improve the release rate of minocycline hydrochloride (MH) and the water absorption capacity using various types of hydrophobic to hydrophilic ointment bases. The effect of purified lanolin (PL) on the release behavior of MH from a hydrophilic ointment (HO) base was the primary focus. It was found that the drug release rate from the ointment base was modified according to the method of preparation of the ointment base and the type of cyclodextrins admixed. The physicochemical properties, such as viscosity, elution volume, and water absorption, of the ointment base were also modified by those factors. To develop an ointment formulation suitable for the recovery stages of bedsores, including the proliferation period of granulation and the formative period of epidermis, the physicochemical properties of Macrogol ointment containing various hydrophilic polymers, which have gel-forming ability, were tested. A novel ointment base suitable for the treatment in the recovery stage of bedsores was developed using hydrophobically modified hydroxypropyl methylcellulose (HM-HPMC). Considerably sustained release of MH (T50 of 170 at a min) was attained with a macrogol ointment mixed with HM-HPMC and Carbopol formulation ratio of 3:7. We clinically evaluated the effectiveness of bedsore treatment by applying different ointment bases to patients with different stages of bedsores.

Characteristics and gel properties of muscles from sardine ( Sardinella gibbosa) and mackerel ( Rastrelliger kanagurta) caught in Thailand

Dark and ordinary muscle from sardine ( Sardinella gibbosa) and mackerel ( Rastrelliger kanagurta) were characterized. Lipid and myoglobin contents were higher in dark muscle than in ordinary muscle of both species, and higher contents of both constituents were found in sardine muscle than mackerel muscle. The extractable myoglobin contents in sardine dark and ordinary muscle were 14.27 and 2.18 mg/g, while mackerel dark and ordinary muscle contained 4.88 and 1.37 mg myoglobin/g sample, respectively. Alkali-soluble protein and stroma contents were greater in dark muscle than ordinary muscle. Mackerel muscle comprised a higher content of non-protein nitrogenous compounds than sardine muscle. The effect of washing conditions on the myoglobin extractability was investigated. A large amount of myoglobin was removed in the first washing cycle and only a small amount was removed in the second washing cycle. The highest removal of myoglobin from sardine (32.10–46.55%) and from mackerel muscle (103.20–313.66%) was achieved when the mince was washed with 0.2% NaCl and 0.5% NaCl, respectively. Washing media showed the marked effect on the color, expressible drip and textural properties of sardine and mackerel mince gels. The breaking force of directly heated and kamaboko gels from both sardine and mackerel mince washed with NaCl solution was higher than that of unwashed mince and water washed mince. However, no difference in deformation was observed. Washing also resulted in increased whiteness and lowered expressible moisture. In general, sardine surimi showed the superior gel-forming ability and whiteness to mackerel surimi.

Seasonal variations in gel-forming ability of rabbit fish

: We studied the potential utilization of rabbit fish (Siganus fuscescens) meat in textured products. We examined the gel-forming ability of rabbit fish caught between July 2001 and August 2002 off the coast of Nagasaki. Fish obtained from approximately July to September (during the spawning season and immediately after), had low gel-forming ability. Fish caught in winter or spring showed high elastic gel formation. Washing of meat with fresh water was found to be important for gel formation. It was concluded that rabbit fish meat has a high gel-forming ability and, therefore, that rabbit fish meat is suitable for textured food production except during the spawning season.

Effect of enzymatic fish-scrap protein hydrolysate on gel-forming ability and denaturation of lizard fish Saurida wanieso surimi during frozen storage

: Fish protein hydrolysate (FPH) was prepared from fish scrap of five marine species by enzymatic treatment for the effective utilization of fish wastes. The major components of the FPH were peptide (82.3–85.8%) with other nitrogenous compounds (11.5–16.3%). Lizard fish Saurida wanieso surimi containing FPH (5.0%, dried weight/wet weight) was stored at −25°C and the suppressive effects of FPH on the decrease in the gel-forming ability, unfrozen water content and Ca-ATPase activity were determined during the frozen storage. FPH maintained a high gel-forming ability and Ca-ATPase activity were determined during the frozen storage. FPH also suppressed the decrease of unfrozen water content of surimi. These results suggest that FPH can be used as a cryoprotectant to suppress the denaturation of muscle protein of lizard fish surimi during frozen storage.

Effect of porcine plasma protein and setting on gel properties of surimi produced from fish caught in Thailand

Effects of porcine plasma protein (PPP) and high temperature setting on gel properties of surimi from bigeye snapper, bigeye croaker, threadfin bream and barracuda were investigated. PPP was effective in increasing breaking force and deformation of kamaboko gels set at 40°C for 30 min and heated at 90°C for 20 min. The optimum levels of PPP were 0.5, 0.5, 1.5 and 1.5 g/100 g and the optimum setting times were 2, 1.5, 1.5 and 2 h for bigeye snapper, bigeye croaker, threadfin bream and barracuda surimi, respectively. However, the addition of PPP significantly decreased whiteness ( P<0.05). An increase in gel-forming ability of surimi with PPP coincided with a decrease in solubility in mixture of SDS, urea and β-mercaptoethanol, indicating the formation of nondisulfide covalent bond induced by both endogenous and plasma transglutaminase. The results supported that PPP improve the gelation of surimi in combination with setting.

Suwari gel properties as affected by transglutaminase activator and inhibitors

Effect of transglutaminase activator and inhibitors on textural properties and cross-linking of myofibrillar proteins in suwari gel of surimi from four fish species, including bigeye snapper, threadfin bream, barracuda and bigeye croaker was investigated. Breaking force and deformation of suwari increased as calcium chloride added increased (P<0.05); however, a slight decrease was observed with an excessive amount of addded calcium chloride. With addition of calcium chloride, the concomitant decrease in solubility of suwari gel, in a mixture of sodium dodecyl sulfate, urea and β-mercaptoethanol, suggested increased non-disulfide covalent bond formation. Conversely, the addition of transglutaminase inhibitors, including N-methylmaleimide (NEM), ammonium chloride and EDTA, resulted in a marked decrease in breaking force and deformation, especially with increasing concentration. The decrease in gel-forming ability was associated with the decrease in non-disulfide covalent cross-linking, as indicate by an increase in solubility and more myosin heavy chain (MHC) retained. The results indicate that endogenous transglutaminase played an essential role in setting, at high temperature (40 °C), of surimi from tropical fish.

Effect of some protein additives on proteolysis and gel-forming ability of lizardfish ( Saurida tumbil)

Effect of beef plasma protein (BPP) and egg white (EW) on proteolysis and gelling properties of lizardfish ( Saurida tumbil) was investigated. Both BPP and EW showed the inhibitory activity toward heat-activated sarcoplasmic proteinases and autolysis of lizardfish mince and washed mince at 60 °C in a concentration-dependent manner. BPP was more effective in proteolysis prevention than EW as shown by more retained myosin heavy chain (MHC) on SDS–PAGE. Effect of BPP and EW (1, 2 and 3%) on the properties of lizardfish surimi prepared under different heating conditions (40/90 °C, 60/90 °C and 90 °C) was also studied. Regardless of heating conditions, incorporation of BPP and EW resulted in the increased breaking force and deformation of surimi gels. Nevertheless, BPP showed higher gel strengthening effect than EW. Addition of BPP resulted in a lower whiteness, while no changes in whiteness were observed with gels added with EW. Therefore, proteolysis of lizardfish muscle or surimi, associated with endogenous proteinase, can be retarded by the addition of BPP or EW, leading to the increased gel strength.

Designing alginate hydrogels to maintain viability of immobilized cells

Hydrogel-forming materials have been widely utilized as an immobilization matrix and transport vehicle for cells. Success in these applications is dependent upon maintaining cell viability through the gel preparation process. We hypothesized that the high viscosity of pre-gelled solutions typically used in these applications may decrease cell viability due to the high shear forces required to mix cells with these solutions. Further, we proposed this harmful effect could be mediated by decreasing the molecular weight ( M w) of the polymer used to form the gel, while maintaining its gel-forming ability. To investigate this hypothesis, alginate was used as model system, as this copolymer consists of cross-linkable guluronic acid (G) blocks and non-cross-linkable blocks. Decreasing the M w of alginate using irradiation (e.g., irradiating at dose of 2 Mrad) decreased the low shear viscosity of 2% (w/w) pre-gelled solutions from 1000 to 4 cP, while maintaining high elastic moduli, once cross-linked to form a gel. Importantly, the immobilization of cells with these polymer hydrogels increased cell viability from 40% to 70%, as compared to using high M w polymer chains to form the gels. Furthermore, the solids concentration of gels formed with the low M w alginate could be raised to further increase the moduli of gels without significantly deteriorating the viability of immobilized cells. This was likely due to the limited increase in the viscosity of these solutions. This material design approach may be useful with a variety of synthetic or naturally occurring block copolymers used to immobilize cells.

Production, Properties, and Some New Applications of Chitin and Its Derivatives

Chitin is a polysaccharide composed from N-acetyl-D-glucosamine units. It is the second most abundant biopolymer on Earth and found mainly in invertebrates, insects, marine diatoms, algae, fungi, and yeasts. Recent investigations confirm the suitability of chitin and its derivatives in chemistry, biotechnology, medicine, veterinary, dentistry, agriculture, food processing, environmental protection, and textile production. The development of technologies based on the utilization of chitin derivatives is caused by their polyelectrolite properties, the presence of reactive functional groups, gel-forming ability, high adsorption capacity, biodegradability and bacteriostatic, and fungistatic and antitumour influence. Resources of chitin for industrial processing are crustacean shells and fungal mycelia. Fungi contain also chitosan, the product of N-deacetylation of chitin. Traditionally, chitin is isolated from crustacean shells by demineralization with diluted acid and deproteinization in a hot base solution. Furthermore, chitin is converted to chitosan by deacetylation in concentrated NaOH solution. It causes changes in molecular weight and a degree of deacetylation of the product and degradation of nutritionally valuable proteins. Thus, enzymatic procedures for deproteinization of the shells or mold mycelia and for chitin deacetylation were investigated. These studies show that chitin is resistant to enzymatic deacetylation. However, chitin deacetylated partially by chemical treatment can be processed further by deacetylase. Efficiency of enzymatic deproteinization depends on the source of crustacean offal and the process conditions. Mild enzymatic treatment removes about 90% of the protein and carotenoids from shrimp-processing waste, and the carotenoprotein produced is useful for feed supplementation. In contrast, deproteinization of shrimp shells by Alcalase led to the isolation of chitin containing about 4.5% of protein impurities and recovery of protein hydrolysate.Referee: Dr. Norman F. Haard, Professor, Institute of Marine Resources, Department of Food Science & Technology, University of California, Davis, CA 95616

CHITOSAN AFFECTS TRANSGLUTAMINASE-INDUCED SURIMI GELATION

Effect of chitosan on barred garfish (Hemiramphus far) surimi gel was studied in the presence of EDTA and microbial transglutaminase (MTGase). An increase in breaking force of surimi gels added with 1.0% prawn shell chitosan indicated the gel enhancing effect of chitosan on the heat-induced gelation of fish myofibrillar proteins. However, gel-forming ability of surimi containing chitosan was inhibited in the presence of EDTA, especially at higher concentration. Therefore, the enhancing effect of chitosan was possibly mediated through the action of endogenous transglutaminase (TGase) during setting, resulting in the formation of protein-protein and protein-chitosan conjugates. In general, addition of MTGase remarkably increased both breaking force and deformation of surimi gel (P<0.05). However, enhancing effect of MTGase was retarded in the presence of chitosan, resulting in lower magnitude of breaking force and deformation (P<0.05). Scanning electron microscopy showed that chitosan particles were uniformly dispersed in the gel matrix. A tightly associated gel network was formed in surimi containing MTGase, whereas a large number of voids were noted in gels with EDTA. These results suggest that chitosan acted as a surimi gel enhancer in combination with endogenous TGase in fish muscle, but hindered gel formation in the presence of MTGase.

Effect of modified atmosphere packaging for keeping gel-forming ability of lizardfish

Effect of modified atmosphere packaging for keeping gel-forming ability of lizardfish

Changes in physico-chemical properties and gel-forming ability of lizardfish ( Saurida tumbil) during post-mortem storage in ice

Changes in physico-chemical properties and gel-forming ability of lizardfish muscle ( Saurida tumbil), stored in ice, were investigated up to 15 days. Heading and eviscerating, prior to iced storage, retarded myosin heavy chain degradation and formaldehyde formation. Additionally, denaturation of myosin and troponin was slightly impeded as monitored by the lower decrease in Ca 2+-ATPase and lower increase in Mg 2+–EGTA-ATPase, respectively. Gel-forming ability of surimi, prepared under different setting and/or heating conditions, decreased as storage time increased ( P<0.05). However, superior breaking force and deformation of surimi gel, from headed/eviscerated fish, to that from whole fish was observed throughout the storage. Whiteness of surimi gel from headed/eviscerated fish was much higher than that from whole fish, especially when the storage time increased. Therefore, storage time and pretreatment were found to be crucial factors, determining the changes in physico-chemical properties and gel-forming ability of lizardfish during iced storage.

Decoloration and Gel‐forming Ability of Horse Mackerel Mince by Air‐flotation Washing

ABSTRACT: The decoloration effects and gel‐forming ability of horse mackerel mince by air‐flotation washing (AFW) was investigated. The lowest residual myoglobin content (RMb) and relative fluorescence intensity (RFI), the highest metmyoglobin (metMb) content and best decoloration effects were recorded for the mince washed with AFW. AFW also effectively improved gel strength in heated surimi. No significant difference in RMb was found when mince was treated with flotation washing using nitrogen, air and ozone. Although the highest metMb content and the lowest RFI were found for the mince washed with ozone, significant differences in whiteness were observed only when the mince was treated with a different gas at 10 or 20 L/min for 5 to 10 min. The physical removal of myoglobin was suggested to be the main factor contributing to accelerated decoloration with AFW.

Functional Characterization of a Protein Concentrate from Bristly Sardine Made Under Acidic Conditions

A protein concentrate from bristly sardine (Opisthonema libertate)was produced under acidic conditions and its gel-forming ability evaluated by texture profile analysis and folding test index. Process protein recovery and lipid removal were greater than 60% and 85%, respectively. A protein-protein aggregate, insoluble in 0.56 M NaCl, was detected during sol preparation. The protein concentrate showed a goodtoexcellent gel-forming ability with an averaged folding test of 4.5. Storage of whole fish for five days at 0°C affected the gel-forming ability of theconcentrate.

Influence of Temperature on the Gel-forming Ability of Some Under-utilized Marine Fish Species in Bangladesh

Influence of Temperature on the Gel-forming Ability of Some Under-utilized Marine Fish Species in Bangladesh

Inhibiting effect of polymerization and degradation of myosin heavy chain during preheating at 30oC and 50oC on the gel-forming ability of walleye pollack surimi

To confirm the contribution of polymerization and degradation of myosin heavy chain (MHC) during preheating to the gel-forming ability of fish meat paste, walleye pollack surimi paste was preheated at 30∞C and 50∞C prior to heating at 80∞C in the presence of various inhibitors. At 30∞C, ethyleneglycol bis(2-aminoethyl ether)-N,N,N¢,N¢-tetraacetic acid (EGTA) and ethylenedi- aminetetraacitic acid (EDTA) inhibited gel formation as well as the polymerization of MHC, whereas dithiothreitol (DTT) and leupeptin promoted gel formation, which was accompanied by the enhance- ment of MHC polymerization and decreased MHC degradation, respectively. At 50∞C, leupeptin inhib- ited MHC degradation and improved gel strength, whereas EGTA, EDTA and DTT had no effect on MHC polymerization and degradation and did not affect gel formation. The results demonstrate that the gel strength of cooked gel (80∞C) is not affected by preheating at 30∞C and 50∞C and does not inhibit polymerization and degradation. Results suggest that the gel strength of cooked gel is depen- dent on the polymerization and degradation of MHC during preheating.

Effect of Alkaline and Acidic Wash Treatments on Functional Properties and Color of Monterey Sardine (Sardinops sagax caerulea)Minced Flesh

Modification of pH during washing showed a beneficial effect on the composition, color and gel-forming ability of Monterey sardine minced flesh. Further improvements in colorand gel-forming ability were achieved by washing under acidic conditions. The proposed washing procedures reduced water usage from 10 to 55% as compared to those used for the washing of dark fleshed fish. Final recoveries after washing were 52% and 49.5% for solids, and 57.4% and 55.8% for protein for acidic and alkaline processes, respectively. Gel-forming ability of mince was compromised as a result of pH modifications. Further studies are required to improve the gel-forming ability of mince by adjusting pH above 6.7 during sol/gel preparation.