Effect of phosphate compounds on gel-forming ability of surimi from bigeye snapper (Priacanthus tayenus)

The properties of surimi gel from bigeye snapper (Priacanthus tayenus) added with various phosphate compounds (sodium pyrophosphate, PP; sodium tripolyphosphate, TPP; and sodium hexametaphosphate, HMP) at different levels (0%, 0.05%, 0.1%, 0.3% and 0.5% w/w) and heated under various conditions were studied. Kamaboko and directly heated gels from bigeye snapper surimi added with 0.05% PP had the increase in breaking force and deformation by 17.35% and 11.52%, and 13.54% and 3.53%, respectively, compared with the control gel (without PP addition). At the same level used (0.05%), TPP had no influence, but HMP exhibited a detrimental effect on kamaboko gel. The addition of PP (0.025%) in combination with 50 mmol CaCl₂/kg increased the breaking force by 38.68% as compared with the control gel (without additives), suggesting that the sufficient amount of CaCl₂ could enhance the setting of the gel. Generally, the marked decrease in breaking force with the coincidental increased expressible moisture was observed when the excessive amount of phosphate compounds was used (p<0.05). Microstructure study revealed that a gel with a fine network was formed with addition of PP. Therefore, the addition of PP in combination with CaCl₂ could increase the gel strength as well as water holding capacity of surimi gel.     

Effects of washing with oxidising agents on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus)

The effects of washing with hydrogen peroxide (H₂O₂) and sodium hypochlorite (NaOCl) solutions on the gel-forming ability and physicochemical properties of surimi produced from bigeye snapper (Priacanthus tayenus), stored in ice for up to 14 days, were investigated. Generally, pH and the trichloroacetic acid (TCA)-soluble peptide content of washed mince varied, depending on the type of oxidizing agent and storage time of the fish. With increasing time of storage, the pHs of water- and H₂O₂-washed mince were lower than that of NaOCl-washed mince (P < 0.05). However, no differences in the TCA-soluble peptide contents of the resulting mince washed with any media were observed (P > 0.05). Washing with 20 ppm NaOCl resulted in the highest increase in both the breaking force and the deformation of mince from fish stored in ice for all the times studied (P < 0.05). Natural actomyosin (NAM) extracted from NaOCl-washed mince had higher surface hydrophobicity and disulfide bond (SS) content than that of water-washed mince (P < 0.05). With no effect on Ca²⁺-, Mg²⁺-, or Mg²⁺–Ca²⁺-ATPase activities, NaOCl washing resulted in an increase in Mg²⁺–EGTA-ATPase activity of NAM (P < 0.05). The results suggested that washing mince with the appropriate type and concentration of oxidizing agent can improve the gelling ability of surimi, particularly from low quality fish.     

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.     

Physicochemical properties and gel-forming ability of surimi from three species of mackerel caught in Southern Thailand

Physicochemical and gelation properties of surimi prepared from three species of mackerel were investigated. The highest whiteness with the lowest redness index corresponding to the lowest myoglobin content especially its oxidised form, metmyoglobin, was found in short-bodied mackerel (Rastrelliger brachysoma) surimi (p < 0.05). Frigate mackerel (Auxis thazard) surimi contained the highest lipid content (p < 0.05). The pH of all surimi was in the range of 6.58–6.80. The highest sulfhydryl group and Ca²⁺-ATPase activity was found in natural actomyosin extracted from short-bodied mackerel surimi (p < 0.05). The highest TCA-soluble peptide content was found in frigate mackerel surimi gels (p < 0.05). Kamaboko gel of short-bodied mackerel surimi exhibited the highest breaking force with the lowest expressible drip (p < 0.05). Heating regime had no effect on deformability of gels from Indian mackerel (Rastrelliger kanagurta) and short-bodied mackerel but not for frigate mackerel. The highest metmyoglobin content with the lowest whiteness was found in frigate mackerel surimi gel (p < 0.05). Therefore, short-bodied mackerel was the best suited for the production of surimi with superior functional attributes including whiteness and gel-forming ability.     

Effects of konjac glucomannan on physicochemical properties of myofibrillar protein and surimi gels from grass carp (Ctenopharyngodon idella)

The cryoprotective effect of konjac glucomannan (KGM) on myofibrillar protein from grass carp (Ctenopharyngodon idella) during frozen storage at −18 °C and the influence of five levels of KGM (0%, 0.5%, 1%, 1.5%, and 2%) on texture properties, water-holding capacity, and whiteness of grass carp surimi gels were investigated. KGM as a novel cryoprotectant could significantly mitigate the decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, and total sulphydryl and active sulphydryl contents of myofibrillar protein during frozen storage. KGM at the level of 1% showed the same good cryoprotective effect as a conventional cryoprotectant (10% sucrose–sorbitol, 1:1, w/w). As the levels of KGM increased, breaking force and deformation of grass carp surimi gels increased significantly. Water-holding properties of the surimi gels are improved with the increasing addition of KGM, but the whiteness decreased and the colour became darker. The optimum addition level of KGM was suggested to be 1%.     

Gelling properties of surimi as affected by the particle size of fish bone

The effects of adding fish bone with two different particle sizes (micro and nano) on Alaska pollock surimi gels prepared by two heating procedures were investigated. Heating procedures (with or without setting) resulted in significantly different gel texture values. The addition of nano-scaled fish bone (NFB) (up to 1 g/100 g) effectively increased gel breaking force and penetration distance while micro-scaled fish bone (MFB) did not. Endogenous transglutaminase (TGase) activity of surimi paste increased obviously as the concentration of NFB increased, indicating calcium ions readily released from NFB and assisting gel formation through TGase-induced covalent bonds. With MFB, TGase activity increased slightly, but not significantly. Scanning electron microscopy (SEM) results revealed NFB was capable of being imbedded in the gel matrices without disrupting the myofibrillar gel network. Surimi with MFB formed a discontinuous and porous network with pores near the size of MFB. Lightness (L*) and whiteness (L*-3b*) of NFB gels were higher than those of MFB.     

Cryoprotective effects of trehalose and sodium lactate on tilapia (Sarotherodon nilotica) surimi during frozen storage

The cryoprotective effects of trehalose and sodium lactate at level of 8% (w/w) in tilapia surimi were studied in comparison with a conventional cryoprotectant (sucrose/sorbitol, 1:1) during extended storage at −18 °C for up to 24 weeks. All present cryoprotectants retarded the protein changes as evidenced by the lowered decrease in salt extractable protein (SEP), Ca²⁺-ATPase activity, total sulfhydryl content as well as the impeded increase in disulfide bond content and surface hydrophobicity. The gel-forming ability of frozen surimi was more retained with addition of cryoprotectants. Among all cryoprotectants used, trehalose exhibited the greatest protective effect on protein denaturation as shown by the effectiveness in maintaining Ca²⁺-ATPase activity and protein solubility. Additionally, the greatest breaking force and deformation were obtained in surimi added with 8% trehalose throughout the frozen storage up to 24 weeks. Sodium lactate showed a similar cryoprotective effect to sucrose/sorbitol blend. Therefore, trehalose and sodium lactate appeared to be promising alternative cryoprotectants for surimi owing to their low sweetness and caloric value.     

Impact of microbial transglutaminase on gelling properties of Indian mackerel fish protein isolates

Impacts of microbial transglutaminase (MTGase) (0–0.6 units/g sample) on gel properties of Indian mackerel unwashed mince, surimi and protein isolates with and without prewashing were studied. Generally, lower myoglobin and lipid contents were found in protein isolate with and without prewashing, compared to those of unwashed mince and surimi (P < 0.05). Protein isolate had the decreased Ca²⁺-ATPase and protein solubility, indicating protein denaturation. When MTGase was incorporated, breaking force and deformation of all gels markedly increased, especially as MTGase levels increased (P < 0.05). At the same MTGase level, gel from protein isolate with prewashing exhibited the highest breaking force and deformation (P < 0.05). The addition of MTGase could lower the expressible moisture content of most gels. No change in whiteness of gel was observed with the addition of MTGase (P > 0.05), but gel from protein isolate gels had decreased whiteness as MTGase at high level was added. The microstructure of protein isolate gels without prewashing showed a similar network to unwashed mince gels, whilst a similar network was observed between surimi gel and gel from protein isolate with prewashing. Nevertheless, a larger void was noticeable in gels from protein isolates. All gels incorporated with MTGase (0.6 units/g) showed a slightly denser network than those without MTGase. Thus, gel with improved properties could be obtained from protein isolate from Indian mackerel with added MTGase.     

Effect of several cryoprotectants on the physicochemical and rheological properties of suwari gels from frozen squid surimi made by two methods

Functionality of squid surimi (Dosidicus gigas) made by two methods (isoelectric precipitation A, and acid washing, B) and stored for 6 months at −15 °C, was analysed as a function of several cryoprotectants. The cryoprotectant effect was studied in terms of the ability to form suwari gels (SA and SB) from the two kinds of surimi. Chemical analyses to detect protein aggregation, dynamic oscillatory tests at constant temperature (10 °C) and temperature sweep tests from 10 to 90 °C were performed.     

Physicochemical properties, gel-forming ability and myoglobin content of sardine (Sardinella gibbosa) and mackerel (Rastrelliger kanagurta) surimi produced by conventional method and alkaline solubilisation process

Characteristics and gel properties of sardine and mackerel surimi produced by conventional washing process and alkaline solubilising process were investigated. The decrease in Ca²⁺-ATPase activity with the changes in the surface hydrophobicity was found in surimi produced by alkaline solubilising process (p<0.05), suggesting the denaturation of protein induced by this process. The alkal-ine solubilising process with prewashing could remove myoglobin most effectively from sardine muscle, whereas the process without prewashing resulted in the greatest myoglobin removal in mackerel muscle (p<0.05). Surimi conventionally prepared by water or NaCl washing showed the gel with greater breaking force and deformation than that from alkaline solubilising process (p<0.05). The hig-her expressible moisture was found in the gels of surimi pre-pared by alkaline process, indicating the poor water holding capacity of the gel matrix. The highest whiteness was found in the gel of sardine surimi produced by alkaline process with prewashing but the highest whiteness was obtained in the gel of mackerel surimi washed with distilled water.     

Biochemical and gelling properties of tilapia surimi and protein recovered using an acid-alkaline process

The biochemical and gel properties of tilapia surimi prepared by a conventional washing method and protein isolated using alkaline-acid-aided processes were studied. Solubility and recovery of protein was found to be highest by using a conventional method, followed by an alkaline- and acid-aided process, respectively. Decreases in myoglobin and lipid contents were found in alkaline- or acid-aided process when compared to the conventional process (p < 0.05). The highest breaking force and deformation of kamaboko and modori gels was found in the gels prepared by the conventional washing method. Higher expressible water and whiteness were found in modori gels when compared to kamaboko gels. TCA-soluble peptide contents of conventional surimi gels were lower than those of acid- and alkaline-recovered protein gels. Degradation of myofibrillar protein was observed in acid-isolated protein. Microstructure of kamaboko gels showed more compact network than in modori gels in both conventional surimi and protein recovered using the pH-shift process.     

Negative effect of combining microbial transglutaminase with low methoxyl pectins on the mechanical properties and colour attributes of fish gels

The objective of this work was to determine the effect of combining different concentrations of microbial transglutaminase (MTGase) and types of low methoxyl (LM) pectin on the mechanical properties (textural profile analysis, puncture test) and the colour attributes of fish restructured products. A disruptive effect was observed when LM pectin and MTGase were added to fish gels. Adding 1% MTGase with LM32 pectin significantly decreased the hardness (3.85 kg), springiness (0.631) and chewiness (0.434 kg). When LM32 pectin and 0.1% MTGase were added together, significant decreases of the three puncture test parameters were observed. The chroma of fish gels decreased significantly when 0.3% MTGase was added. Fish gels containing the LM35 pectin had higher chroma values than all other fish gels with the same level of MTGase. Hue value was increased in all fish gels after increasing the MTGase level. The results obtained showed that LM pectin is not suitable for use in products containing MTGase.     

食品酶制剂对冷冻面团流变学和微结构的影响

应用动态流变仪,Brabender拉伸仪,扫描电子显微镜(SEM)研究了葡萄糖氧化酶和谷氨酰胺转胺酶对冷冻面团粘弹模性量粘弹模量,抗拉伸阻力R5及微结构影响。空白面团(未加添加剂),含有葡萄糖氧化酶面团和含有谷氨酰胺转胺酶面团于-18℃冷冻贮藏7,21,35d,随冷冻贮藏时间延长,面团弹性模量(G′)降低。在同一冷冻贮藏时期内空白面团弹性模量最小,添加葡萄糖氧化酶面团弹性模量最大;含有葡萄糖氧化酶和含有谷氨酰胺转胺酶面团抗拉伸阻力R5大于空白面团。葡萄糖氧化酶和谷氨酰胺转胺酶使新鲜面团(未冷冻面团)面筋网络增强,淀粉颗粒镶嵌于交错的面筋网络之间,在-18℃经过35d冷冻贮藏,空白面团面筋网络不再连续,支离破碎,并与淀粉颗粒分离,而且面筋膜变薄。含有葡萄糖氧化酶和含有谷氨酰胺转胺酶面团依然有大量连续面筋网络存在。葡萄糖氧化酶和谷氨酰胺转胺酶抑制了面团弹性模量和抗拉伸阻力R5的恶化,而且抑制冰晶对面团中面筋三维网络结构的破坏。     

The effect of whitening agents on the gel-forming ability and whiteness of surimi

The effect of different concentrations of the whitening agents, calcium carbonate, titanium dioxide and soybean oil, on the gel‐forming ability and whiteness of a mixture of bigeye snapper and mackerel surimi was investigated. The whiteness of the surimi gels increased as the concentration of all whitening agents increased (P < 0.05). Titanium dioxide was a good whitening agent and it had no detrimental effects on gel‐forming ability, while oil reduced the gel breaking force and deformation. The addition of calcium carbonate did not result in a marked increase in whiteness, but it did increase the breaking force and deformation to some extent. The different whitening agents showed different influences on the whiteness and gelling characteristics of surimi gel.     

Transglutaminase effects on gelation capacity of thermally induced beef protein gels

Transglutaminase (TG) is an enzyme that catalyzes an acyl-transfer reaction between the γ-carboxyamide group of peptide or protein-bound glutaminyl residues, and primary amines. TG action on protein molecules, causes a cross-linking and polymerizing effect of these latter, through ε-(γ-glutamyl)lysine bonds. This TG-mediated protein cross-linking creates drastic physical changes in protein-rich foods.     

Comparison of Atlantic menhaden gels from surimi processed by acid or alkaline solubilization

Heat-induced gelling abilities of surimis prepared by pH shifting (isoelectric precipitation following acid (AC) or alkaline (AL) solubilization) were compared to that of conventionally washed (CW) surimi. Greater endogenous transglutaminase activity (evidenced as enhanced strength of cooked gels subjected to 30–40 °C preincubation) was measured for CW and AL surimi than for AC surimi (all at pH 7). Upon addition of microbial transglutaminase (MTGase), increased crosslinking of myosin heavy chain and gel strengthening during 30–40 °C preincubation were apparent for all three types of surimi, most markedly in CW and AL surimi. Salt addition improved CW gels most, but seemed to adversely affect MTGase activity in AC and AL surimi. AC and AL surimi gels were of lower whiteness than were CW surimi gels.     

Effect of oxidised tannic acid on the gel properties of mackerel (Rastrelliger kanagurta) mince and surimi prepared by different washing processes

Effect of oxidised tannic acid (OTA) at different levels (0, 0.25, 0.50 and 0.75% of protein content) on the gel properties of mackerel (Rastrelliger kanagurta) mince and surimi prepared by different washing processes was investigated. Breaking force and deformation of gels varied with washing processes and concentrations of OTA. The gel of alkaline-saline washing process surimi (ASWPS) added with 0.25% OTA had the increases in breaking force and deformation by 166.2 and 45.9%, respectively, compared with that of conventional washing process surimi (CWPS) without OTA addition. Those increases were associated with the lowered expressible moisture content. Electrophoretic studies revealed that the greater polymerisation was found in ASWPS added with 0.25% OTA. Slight retention of myosin heavy chain (MHC) with lowered trichloroacetic acid (TCA) soluble peptide contents was observed in ASWPS gel added with 0.25% OTA, suggesting the decreased degradation induced by indigenous proteases. The microstructure of ASWPS gels became more ordered, compact and denser with the addition of 0.25% OTA. The use of OTA in conjunction with alkaline-saline washing process could improve the properties of gel from mackerel surimi without adverse effect on sensory properties.     

Whey protein concentrate: Autolysis inhibition and effects on the gel properties of surimi prepared from tropical fish

Effects of whey protein concentrate (WPC) on autolysis inhibition and gel properties of surimi produced from bigeye snapper (Priacanthus tayenus), goatfish (Mulloidichthys vanicolensis), threadfin bream (Nemipterus bleekeri) and lizardfish (Saurida tumbil) were investigated. WPC (0–3%) showed inhibitory activity against autolysis in all surimi at both 60 and 65 °C in a concentration-dependent manner. Myosin heavy chain (MHC) of surimi was more retained in the presence of WPC. Breaking force and deformation of kamaboko gels of all surimi increased as added levels of WPC increased (P < 0.05). This was associated with lower levels of protein degradation, as evidenced by the decrease in trichloroacetic acid-soluble peptide content (P < 0.05). WPC at 3% (w/w) significantly decreased the whiteness of gels. However, water-holding capacity of kamaboko gels was improved with increasing concentration of WPC. The microstructure of surimi gels generally became denser with the addition of WPC.     

Effect of oxidised phenolic compounds on the gel property of mackerel (Rastrelliger kanagurta) surimi

The effects of different oxidised phenolic compounds (ferulic acid, OFA; tannic acid, OTA; catechin, OCT and caffeic acid, OCF) at different levels (0-0.60% of protein content) on the properties of gels from mackerel (Rastrelliger kanagurta) surimi were investigated. Gels with addition of 0.40% OFA, 0.50% OTA, 0.50% OCF or 0.10% OCT had increases in breaking force by 45%, 115%, 46.1% and 70.3% and in deformation by 12.2, 27.5, 28.1 and 28.4%, respectively, compared with the control (without addition of oxidised phenolics). Lowered expressible moisture content without any change in the whiteness of resulting gels was found. Slightly lower myosin heavy chain (MHC) band intensity of gels added with oxidised phenolics at the optimal level was noticeable compared with that of the control. A sensory evaluation study indicated that addition of oxidised phenolic compounds had no negative impact on the colour and taste of the resulting gels (P > 0.05). Gels with addition of all oxidised phenolics had a finer matrix with smaller strands.