Mackerel Surimi Research Articles

Relatively Low Lecithin Inclusion Improved Gelling Characteristics and Oxidative Stability of Single-Washed Mackerel (Auxis thazard) Surimi.

The effect of lecithin addition on the gelling characteristics and oxidative stability of single-washed mackerel (Auxis thazard) surimi was investigated in this study. Surimi was chopped in the presence of 2.5% (w/w) NaCl with different concentrations of lecithin (0, 0.1, 0.5, 1, and 1.5 g/100 g surimi). The rheological behavior, gel-forming ability, microstructure, and lipid oxidation of lecithin-added surimi varied significantly depending on lecithin content. When compared to the control, lecithin at 0.1, 0.5, and 1 g/100 g improved the breaking force of the gel (p < 0.05). The breaking force of the gel decreased significantly as lecithin concentration increased (up to 1.5 g/100 g) (p < 0.05). Deformation, on the other hand, reacted differently to the lecithin than it did to the breaking force. At a lecithin level of 0.1 g/100 g, the surimi gel displayed improved deformation (p < 0.05). Nonetheless, at higher doses (0.5-1.5 g/100 g), lecithin considerably reduced surimi gel deformation (p < 0.05), and the gel containing lecithin at 1.5 g/100 g showed significantly decreased deformation. Surimi with 0.1 g/100 g lecithin had the lowest expressible drip (p < 0.05). In general, lecithin at concentrations ranging from 0.1 to 1 g/100 g reduced expressible drip (p < 0.05), but not at 1.5 g/100 g, which was equivalent to the control (p > 0.05). Adding lecithin to mackerel surimi improved its whiteness slightly, regardless of concentration. Lecithin impacted the microstructures of surimi gel in a concentration-dependent manner. Lecithin at a concentration of 0.1 g/100 g produced a densely packed network with small, jointed clusters and minimal holes within the gel. Joined clusters in the gel were reduced by 0.5-1.5 g/100 g lecithin, and continuous aggregates predominated. Surprisingly, at higher doses of lecithin, notably 1.5 g/100 g, porous structures with continuous voids were perceived. Surimi gels treated with various lecithin doses had lower thiobarbituric acid reactive substances (TBARS) levels than the control (p < 0.05). Overall, lecithin at a low concentration of 0.1 g/100 g was most effective at improving the texture, increasing water-holding capacity, lightening the color, and delaying lipid oxidation of single-washed mackerel surimi.

Evaluation of the Improvement Effect of Whey Protein Poly-Peptides on Quality Characteristics of Repeated Freeze–Thawed Spanish Mackerel Surimi Balls

This investigation aimed to assess the effects of whey protein hydrolysate (WPH) on the oxidative stability of protein and the ability of Scomberomorus niphoniu surimi balls to retain water after repeated freeze-thaw (F-T) cycles. Ten percent natural whey peptides (NWP), 5% WPH, 10% WPH, 15% WPH, 0.02% butyl hydroxyl anisole (BHA), and a control group that did not receive any treatment were the six groups that were employed in the experiment. The cooking loss, water retention, total sulfhydryl content, and carbonyl content of each group were all measured. Notably, it was found that the surimi balls’ capacity to hold onto water and fend off oxidation was enhanced in a dose-dependent manner by the addition of WPH. Furthermore, the results showed that the 15% WPH added to the surimi balls effectively decreased protein oxidation in the F–T cycles and ameliorated the texture deterioration of surimi balls induced by repeated F–T, laying a theoretical foundation for the industrial application of WPH in surimi products.

Protection of Whey Polypeptide on the Lipid Oxidation, Color, and Textural Stability of Frozen-Thawed Spanish Mackerel Surimi.

Repeated freeze-thaw (FT) cycles can have an impact on surimi quality. In this study, we used 0.02% BHA as a positive control group. We examined the effects of different concentrations (0%, 5%, 10%, and 15%) of whey protein hydrolysate (WPH) on surimi, focusing on alterations in color metrics (L* for brightness, a* for red-green, b* for yellow-blue, and overall whiteness), textural characteristics, and antioxidant capacity during various freeze-thaw (FT) cycles. The results showed that the lipid oxidant values of surimi, as well as its a* and b* values, rose as the number of FT cycles increased; whereas the adhesiveness, resilience, gumminess, and shear force dropped, as did L* and the whiteness values, leading to an overall darkening of color and gloss. By contrast, the study found that the addition of WPH could effectively slow down the decrease of surimi textural stability after repeated freeze-thawing, with the textural stability of the group with 15% WPH being significantly superior to those of the other groups (p < 0.05). Under the same number of cycles, adding 15% WPH to the experimental group could successfully lower total volatile basic nitrogen (TVB-N) and effectively increase the antioxidant activity of surimi. This finding suggested that 15% WPH had the greatest effect on increasing surimi FT stability. To conclude, it was proved that WPH can be added to frozen surimi and improve its quality.

Surimi Production from Tropical Mackerel: A Simple Washing Strategy for Better Utilization of Dark-Fleshed Fish Resources

Mackerel (Auxis thazard), a tropical dark-fleshed fish, is currently a viable resource for the manufacture of surimi, but the optimal washing procedure for more efficient use of this particular species is required right away. Washing is the most critical stage in surimi production to ensure optimal gelation with odorless and colorless surimi. The goal of this study was to set a simple washing medium to the test for making mackerel surimi. Washing was performed three times with different media. T1 was washed with three cycles of cold carbonated water (CW). T2, T3, and T4 were washed once with cold CW containing 0.3%, 0.6%, or 0.9% NaCl, followed by two cycles of cold water. T5, T6, and T7 were produced for three cycles with CW containing 0.3%, 0.6%, or 0.9% NaCl. For comparison, unwashed mince (U) and conventional surimi washed three times in cold tap water (C) were employed. The maximum yield (62.27%) was obtained by washing with T1. When varying quantities of NaCl were mixed into the first washing medium (T2–T4), the yield decreased with increasing NaCl content (27.24–54.77%). When washing with NaCl for three cycles (T5–T7), the yield was greatly decreased (16.69–35.23%). Conventional surimi washing (C) produced a yield of roughly 40%, which was comparable to T3. Based on the results, treatments that produced lower yields than C were eliminated in order to maximize the use of fish resources and for commercial reasons. The maximum NaCl content in CW can be set at 0.6% only during the first washing cycle (T3). Because of the onset of optimal unfolding as reported by specific biochemical characteristics such as Ca2+-ATPase activity (0.2 μmol inorganic phosphate/mg protein/min), reactive sulfhydryl group (3.61 mol/108 g protein), and hydrophobicity (64.02 µg of bromophenol blue bound), T3 washing resulted in surimi with the greatest gel strength (965 g.mm) and water holding capacity (~65%), with fine network structure visualized by scanning electron microscope. It also efficiently removed lipid (~80% reduction), myoglobin (~65% reduction), non-heme iron (~94% reduction), and trichloroacetic acid-soluble peptide (~52% reduction) contents, which improves whiteness (~45% improvement), reduces lipid oxidation (TBARS value &lt; 0.5 mg malondialdehyde equivalent/kg), and decreases the intensity of the gel’s fishy odor (~30% reduction). As a result, washing mackerel surimi (A. thazard) with CW containing 0.6% (w/v) NaCl in the first cycle, followed by two cycles of cold water washing (T3), can be a simple method for increasing gel-forming capability and oxidative stability. The mackerel surimi produced using this washing approach has a higher quality than that produced with regular washing. This straightforward method will enable the sustainable use of dark-fleshed fish for the production of surimi.

Single Ultrasonic-Assisted Washing for Eco-Efficient Production of Mackerel (Auxis thazard) Surimi.

This study highlights a promising single washing method for producing dark-fleshed mackerel surimi aided by ultrasonication in conjunction with cold carbonated water containing 0.6% NaCl and mixed antioxidants (0.5% EDTA/0.2% sodium erythorbate/0.2% sodium tripolyphosphate) (CSA). Different washing periods (5, 10, and 15 min) with and without ultrasound were tested. Unwashed mince (A1) and conventional water-washed surimi (10 min/cycle, 3 cycles) (A2) were used as controls. A3, A4, and A5 were subjected to ultrasound-assisted washing for 5, 10, and 15 min, respectively, whereas A6, A7, and A8 had non-ultrasound-assisted washing for 5, 10, and 15 min. Results showed that the surimi yield decreased as the ultrasonic treatment time increased from 5 to 15 min (p < 0.05). Increased ultrasonic time resulted in greater protein denaturation, protein oxidation, myoglobin removal, and lipid oxidation in surimi (p < 0.05). Surimi produced by CSA ultrasonication for 5 min (A3), on the other hand, had a comparable overall quality to A2 surimi (p > 0.05). The correspondence gel (A3) outperformed the control gel (A2) in terms of gel strength, whiteness, and water-holding capacity (p < 0.05). The formation of regularly continuous, more organized, and smooth network structures in surimi gel was observed in A2 and A3 gels, whereas sparse and larger pore sizes were noticed in surimi gels produced by longer ultrasonic treatment. All of the surimi gels had identical FTIR spectra, indicating that the functional groups of the protein gel were consistent throughout. As a result, a single 5 min CSA-ultrasonic washing could potentially yield surimi of comparable quality to conventional washing. This could pave the way for the development of dark-fleshed fish surimi, which would require less washing time and produce less waste water.

Impact of Washing with Antioxidant-Infused Soda-Saline Solution on Gel Functionality of Mackerel (Auxis thazard) Surimi.

Mackerel (Auxis thazard), a tropical dark-fleshed fish, has the potential to be used in the production of surimi. It is necessary to identify the optimal washing method to make better use of this species since efficient washing is the most important step in surimi processing to ensure maximal gelling and high-quality surimi. The purpose of this study was to evaluate the combined effect of cold carbonated water (CW) with NaCl and antioxidants in washing media, so-called antioxidant-infused soda-saline solution, on lipid and myoglobin removal efficacy, biochemical characteristics, gelling properties, sensory features, and the oxidative stability of mackerel surimi in comparison with unwashed mince (T1) and conventional water washed surimi (T2). Mackerel mince was washed with CW in the presence of 0.6% NaCl at a medium to mince ratio of 3:1 (v/w) without antioxidant (T3) or with the addition of 1.5 mM EDTA plus 0.2% (w/v) sodium erythorbate and 0.2% sodium tripolyphosphate (T4), 100 mg/L gallic acid (T5), and 5 mM citric acid containing 8 mM calcium chloride (T6). During the first washing cycle, the antioxidants were mixed into the washing medium. The second and third washing cycles were then completed with cold water. The yields of all treatments were roughly 75-83%, based on the gross weight of the raw mince. The pH of the surimi was in a range of 5.47-6.46. All of the surimi had higher reactive sulfhydryl (SH) content and surface hydrophobicity but lower Ca2+-ATPase activity than unwashed mince (p < 0.05). After washing, lipids decreased significantly (p < 0.05), accounted for a 65-76% reduction. The T2 surimi had the highest peroxide value (PV). T1 had the lowest conjugated diene value. T1 and T4 surimi had the lowest TBARS value (p < 0.05). A lower non-heme iron level was found in all antioxidant-treated samples than in T1. Washing can increase the redox stability of myoglobin regardless of the washing media, as seen by the relatively low metmyoglobin levels. According to the dynamic viscoelastic behavior, all surimi and unwashed mince underwent the same degree of sol-gel transition following heat gelation. T1 showed the lowest breaking force, deformation, gel strength, and whiteness (p < 0.05). Surimi made from T4 or T5 had the highest gel strength when both breaking and deformation were considered, but the latter's expressible drip was noticeably higher. Surimi gel appears to be stabilized against lipid oxidation, as demonstrated by low PV and TBARS levels, when produced with T4. Because of the low level of TBARS, all 10 panelists rated rancid odor as low (~1 out of 4), with no significant variations across treatments. Only treatments with T4 and T6 tended to have a lower fishy odor score as compared to unwashed mince. Scanning electron microscope demonstrated that surimi gels washed with all washing media exhibited microstructures that were very comparable, with the exception of the T6 treatment, which had big pores and aggregates. Based on the quality features, T4 appeared to be the optimal medium to enhance the gel functionality of mackerel surimi.

Comparative Effect of Cricket Protein Powder and Soy Protein Isolate on Gel Properties of Indian Mackerel Surimi.

This work comparatively investigated the effects of different levels (0, 1, 3, and 5%, w/w) of cricket protein powder (CP) and soy protein isolate (SPI) on the gel properties of mackerel surimi. Both SPI and CP enhanced the rheological properties of surimi pastes during heating, as indicated by the increase in G' and G″ and the decrease in tan δ. With increasing SPI content, the proteolytic inhibition, gel properties, water-holding capacity, and textural profiles of surimi gel were markedly enhanced. Molecular driving-force results showed that SPI markedly promoted the hydrophobic interaction, while disulfide bonds were dominant in CP-added gel. However, the whiteness of surimi gels tended to decrease with the increased levels of both additives, in particular CP. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that SPI hindered the polymerization of myosin heavy chain while CP participated in the formation of non-disulfide covalent bonds with actin. Fourier transform infrared (FTIR) spectra indicated that CP and SPI did not influence the secondary structure of proteins in surimi. Scanning electron microscopy (SEM) demonstrated that CP or SPI induced the myofibrillar protein to form smoother and compact gel network structures. Overall acceptability of the mackerel surimi gel can be improved by the incorporation of 5% SPI while CP had a negative impact on several parameters. However, CP showed the remarkable ability to prevent the lipid oxidation of the gel after storage at 4 °C for 7 days. Overall, both SPI and CP demonstrated positive impacts on the gelling characteristics of mackerel surimi; however, SPI was more advantageous than CP in terms of the gel-strengthening effect and sensory qualities. This study offered a potential use for plant and insect proteins as functional and nutritional ingredients for the production of dark-fleshed fish surimi.

UV irradiation improved gel properties and chill‐stored stability of surimi gel

SummaryThe study investigated the properties and storage stability of Japanese Spanish mackerel (Scomberomorus niphonius) surimi gel exposed to ultraviolet irradiation for 0.5, 1, 2 and 3 h (UV0.5, UV1, UV2, UV3) before thermal treatment. The results showed that all UV‐irradiated surimi gels exhibited compact microstructure along with increased gel strength and water‐holding capacity than control. Investigations on chemical properties of myofibrillar protein (MP) from surimi showed that tryptophan fluorescence intensity declined while bromophenol blue‐binding capability increased after UV irradiation. Sulfhydryl content in MP of UV2 and UV3 decreased while their carbonyl content increased. Electrophoresis analysis indicated that myosin heavy chain of UV2 was most attenuated. Storage test showed that UV2 maintained the highest gel strength during chilled‐storage and its total viable count was below 5 log10CFU•g−1 after 18 days. Therefore, UV irradiation might be applied to improve surimi gel properties and extend shelf life.

Reduced Washing Cycle for Sustainable Mackerel (Rastrelliger kanagurta) Surimi Production: Evaluation of Bio-Physico-Chemical, Rheological, and Gel-Forming Properties.

Although dark muscle is currently the most important obstacle in marketing high-quality Indian mackerel (Rastrelliger kanagurta) surimi, reducing washing remains a challenge for long-term surimi production from this species. Herein, the impact of washing cycles (one (W1), two (W2), and three (W3) cycles) with a 1:3 mince to water ratio on the bio-physico-chemical properties, rheology, and gelling ability of mackerel surimi was evaluated. The yield, Ca2+-ATPase activity, TCA-soluble peptide, and myoglobin contents of surimi decreased as the number of washing cycles increased, while lipid removal, reactive SH content, and surface hydrophobicity of surimi increased. Surimi generated by W2 and W3 provided the same rheological patterns and Fourier-transform infrared spectroscopy (FTIR) spectra as unwashed mince, with the highest gel strength and whiteness, as well as the lowest expressible drip, thiobarbituric acid reactive substances (TBARS), and fishy odor. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated the presence of polymerized proteins stabilized by disulfide and other interactions. Using a scanning electron microscope, several concentrated dense areas and distributed pores generated by myofibrillar proteins gel networks were found. Surimi from W2 and W3 appeared to be of similar overall quality, however W2 had a larger yield. As a result of the evaluation of bio-physico-chemical, rheological, and gel-forming capabilities, as well as product yield, W2 may be the best option for producing high-quality surimi from Indian mackerel in a sustainable manner.

Biochemical property and gel-forming ability of mackerel (Auxis thazard) surimi prepared by ultrasonic assisted washing.

A low gel-forming ability is needed to be encountered using the dark-fleshed fish as a raw material. Optimal washing process can be a principled way of improving the gelling properties because washing is the most important step for surimi production. This study aimed to investigate the effect of ultrasonic-assisted washing (UAW) on the biochemical properties and gel-forming ability of frigate mackerel (Auxis thazard) surimi. Unwashed mince and conventional washing (CW) with 3-cycle of water (10 min per cycle) were compared to UAW for 5 and 10 min per cycle. UAW tended to improve the lipid removal, reduce the TCA-soluble peptide, and increase the surface hydrophobicity of surimi, but it had no influence on the Ca2+-ATPase activity, reactive sulfhydryl content, haem protein content, and lipid oxidation. UAW for 5 min per cycle rendered the surimi with the highest gel strength, whiteness, and water holding capacity as well as a regular aggregated network. With this method, the washing time can be reduced to 50% compared to the CW. Therefore, UAW for 5 min per cycle was an alternative approach for the production of mackerel surimi.

Premix Flour for Preparation of Empek-Empek Based on Surimi Technology

Empek-empek is one of signatured food from Indonesia which made from fish paste, tapioca starch, and other additional ingredients. The objective of this present work was to develop premix flour for making empek-empek using mackerel surimi and to evaluate their chemical characteristic and sensory attributes of the product. The mackerel fish was made into surimi, powdered, then mixed with tapioca starch and other additional ingredients. The following aspect were characterized including moisture, fat, protein, ash, carbohydrate content, and sensory acceptability of the premix product. The results showed that mackerel surimi flour at level of 66,67% is the recommended formula. The empek-empek which made from this premix flour presented hedonic score “like” for color and “like moderately” for aroma, texture and flavor. In conclusion, our premix can be used for preparing empek-empek with less complicated process and the product did not have any negative results on sensory acceptability.

Physiochemical properties and tastes of gels from Japanese Spanish mackerel (Scomberomorus niphonius) surimi by different washing processes.

The study investigated the properties of gels from Japanese Spanish mackerel (Scomberomorus niphonius) (JSM) surimi received conventional washing (CW) or alkaline-saline washing (AW) and un-washing (UW). AW gel exhibited the highest breaking force and deformation as well as water-holding capacity, but CW gel only had higher breaking force than UW gel. Low-field NMR analysis showed that peak P22 in AW gel was shifted to higher relaxation time and the areas of peak P21 and P22 in AW gel were higher than those in UW and CW gels. Compared with UW gel, network structure of AW gel was more continuous with many tiny voids, but CW gel microstructure showed partially uneven area with large voids. SDS-PAGE showed that band intensity of myosin heavy chain attenuated more in AW gel than in UW and CW gels in nonreducing electrophoresis and it recovered more pronounced in reducing electrophoresis. Solubility attributed to hydrophobic interaction, hydrogen and disulfide bonds increased in CW and AW gels. AW gel gave stronger bitterness and aftertaste A while CW gel showed heavier sourness, astringency, and aftertaste B than UW gel. Results suggest that AW improved physiochemical properties of gel and preserved a closer taste pattern to UW gel. It is recommended for JSM surimi producing. PRACTICAL APPLICATIONS: Surimi food has great potential due to its convenience, elasticity, and nutritional value. Japanese Spanish mackerel (JSM), a popular fish species in China, is widely used for producing surimi food, such as fish ball, dumpling, and sausage. Washing is a practical way to improve its gel properties. This study investigated the gel strength, water status, protein pattern, molecular interactions, microstructure, color, and taste of gels from JSM surimi received conventional washing or alkaline-saline washing and un-washing. Some practical information of effects of washing on gel properties was obtained. These results provide supports to the gel properties improvement by appropriate washing for JSM.

Premix formulation for making the Indonesian otak-otak

Otak-otak is one indigenous foods from Indonesia which made from fish paste, tapioca flour and spices. The aim of this research was to produce premix flour for making otak-otak using mackerel surimi, tapioca flour and spices and to evaluate their chemical properties and sensory acceptability of the product. Mackerel surimi was first dried, miled into powder form then mixed with tapioca flour and spices. The result showed that, otak-otak which made from Premix-B formula (40% mackerel surimi powder and 60% tapioca flour) was the best result for all sensory attributes. It presented “like moderately” for hedonic score. Protein, ash, moisture, carbohydrate, and fat contents of the premix-B formula were 23.51%, 2.44%, 7.31%, 71.02%, 4.28%, respectively, which met the SNI requirements. Overall, this study clearly showed that it was possible to make otak-otak with less complicated process and the product did not have any negative results on sensory perception.

Carbonated water as a novel washing medium for mackerel (Auxis thazard) surimi production.

Effect of cold carbonated water (CW) washing on the biochemical properties and gel characteristics of mackerel surimi was evaluated. Three washing cycles were performed with different orders of washing medium including T1 (water, water and water), T2 (CW, water and water), T3 (CW, CW and water) and T4 (CW, CW and CW). The results showed that CW washing, especially T4, caused the decrease in pH, Ca2+-ATPase activity and surface hydrophobicity and led to the increase in reactive sulfhydryl content. Regardless of washing treatment, haem protein of surimi decreased significantly compared to unwashed mince. However, carbonated water did not improve haem protein removal. The highest lipid reduction was found in T1 and T2. Gels from all CW washing treatments had a comparable whiteness. Breaking force of CW surimi gel increased with increasing washing cycle (T2<T3<T4). Deformations of all surimi gels were not much different (~7mm). Expressible drip increased with increasing CW washing cycle. Numbers of jointed spherical matrices were found in surimi gel microstructures. With increasing CW washing cycle, densely packed aggregates were formed. Therefore, CW washing with appropriate cycle can be used as an alternative means for mackerel surimi production.

アイゴ,ワニエソ,マアジすり身の凍結貯蔵耐性に及ぼす糖添加の影響

アイゴ,ワニエソ,マアジすり身の凍結貯蔵耐性に及ぼす糖添加の影響

EFFECT OF KIAM WOOD EXTRACT AS INFLUENCED BY pH DURING OXYGENATION ON MACKEREL SURIMI GEL

Impact of ethanolic kiam wood extract (EKWE) oxygenated at various pHs on the properties of gels from mackerel (Rastrelliger kanagurta) surimi was studied in comparison with commercial tannin (CT). When 0.3% CT and 0.15% EKWE oxygenated at alkaline pHs (8 and 9) were incorporated, surimi gel had the increases in breaking force by 123.4–135.7% and 136.9–157.5%, respectively, while the deformation was increased by 20.9–38.1% and 33.7–48.2%, respectively, compared with those of the control (P < 0.05). Those increases were associated with the lowered expressible moisture content and the disappearance of myosin heavy chain band intensity. However, CT and EKWE oxygenated at pH 3 and 7 showed no pronounced effect. Gels added with 0.15% EKWE oxygenated at alkaline pH had the finer matrix with smaller strands and voids. Thus, the pH for oxygenation of phenolic compounds in EKWE had the impact on the gel strength of mackerel surimi. PRACTICAL APLICATIONS Gel strength is a prime factor determining the quality and price of surimi. Several additives have been used to improve the gel strength. Recently the use of phenolic compounds in their oxidized form effectively enhanced gel strength of surimi. The extract from kiam wood is another natural additive exhibiting gel strengthening effect. Oxygenation of the extract at alkaline pH could increase the efficacy of the extract, in which the lower amount was required and no negative effect on the resulting gel was obtained.

Gelling Properties of Spanish Mackerel (Scomberomorus niphonius) Surimi as Affected by Washing Process and High Pressure

This study evaluated the effect of washing conditions on gel properties of Spanish mackerel and investigated the application of high pressure to improve the gel properties of Spanish mackerel. Alkaline-saline washing process surimi (ASWPS) showed the increase in gel strength by 40.19% than unwashed surimi, and by 26.74% than conventional washing process surimi (CWPS). These increases were associated with the lowered expressible moisture content. However, no differences were found in deformation of gels prepared by different washing processes. Electrophoretic studies revealed that ASWPS had the highest MHC and actin band intensity. Alkaline-saline washing process surimi was subjected to ultra-high pressures of 100, 200, 300, 400, 500 MPa for 30 min at 40°C. The effects of pressure on both springiness and cohesiveness were insignificant. Hardness and chewiness of samples treated at 300 and 400 MPa increased significantly when compared with the control, which increase by 2.68 and 2.40 times at 300 MPa and by 2.87 and 2.70 times at 400 MPa, respectively. However, these values slightly decreased after treatment at 500 MPa. In addition, pressure increased the whiteness of surimi, the higher pressure the more increase.

Gel properties of croaker–mackerel surimi blend

Gel properties of croaker surimi blended with three types of mackerel surimi at different ratios were evaluated. The gel strength of the croaker–mackerel surimi blend was higher than that of the original mackerel surimi ( p < 0.05). The presence of croaker surimi in the blend resulted in the increase in myosin heavy chain (MHC) band intensity. No differences in deformation of gels were observed in croaker surimi and croaker-short-bodied mackerel blend at all ratios ( p > 0.05). The addition of short-bodied mackerel surimi into croaker surimi up to a ratio of 1:2 had no effect on whiteness and metmyoglobin content of the gel ( p > 0.05). Marked decrease in expressible drip and TCA-soluble peptide of gel was noticeable in croaker–frigate mackerel surimi blend ( p < 0.05). Therefore, the gel properties of croaker–mackerel surimi blend were governed by the type and content of mackerel surimi used.

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.

Gel Strengthening Effect of Wood Extract on Surimi Produced from Mackerel Stored in Ice

The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel (Rastrelliger kanagurta) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously (P < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.