Emulsion Surimi Gel with Tunable Gel Properties and Improved Thermal Stability by Modulating Oil Types and Emulsification Degree

High resistance to heating treatments is a prerequisite for ready-to-eat (RTE) surimi products. In this study, emulsion-formulated surimi gels were prepared, and the effects of oil types and emulsification degrees on the thermal stability of surimi gel were investigated. The results showed the gel properties of surimi gels were modulated by oil types and emulsification degrees. In detail, the rising pre-emulsification ratio caused the increase of the emulsifying activity index (EAI) and decrease of emulsifying stability index (ESI) for both emulsions. The larger droplet sizes of perilla seed oil than soybean oil may be responsible for their emulsifying stability difference. The gel strength, water retention, dynamic modulus and texture properties of both kinds of surimi gels displayed a firstly increased and then decreased tendency with the rising pre-emulsification ratios. The peak values were obtained as perilla seed oil emulsion with emulsification ratio of 20% group (P1) and soybean oil emulsion with emulsification ratio of 40% group (S2), respectively. Anyway, all emulsion gels showed higher thermal stability than the control group regardless of oil types. Similar curves were also obtained for the changes of hydrogen bond, ionic bond and hydrophobic interactions. Overall, perilla seed oil emulsion with emulsification ratio of 20% (P1 group) contributed to the improved thermal stability of surimi gels.

Improvement of Gel Quality of Squid (Dosidicus gigas) Meat by Using Sodium Gluconate, Sodium Citrate, and Sodium Tartrate

In order to improve the quality of squid surimi products, squid surimi gels were prepared using several types of organic salts under two heating conditions to study the effects of organic salts on squid gel properties. Compared with the NaCl group, organic salts reduced the solubilization capacity of myofibrillar protein, and significant (p < 0.05) decreases in the breaking force, breaking distance, texture, and water-holding capacity of the gel were observed in the sodium gluconate group, while significant (p < 0.05) increases in the breaking force, breaking distance, texture, and water-holding capacity of the gel were observed in the sodium citrate and sodium tartrate groups. Although the mixed addition of NaCl and organic salt improved surimi gel quality, the effective improvement was still lower than that of only organic salt. Rheological properties indicated that sodium citrate and sodium tartrate had high viscoelasticity. The squid surimi gel prepared by direct heating exhibited better properties than gels prepared by two-step heating. The chemical force of squid gel prepared with sodium citrate and sodium tartrate formed a stronger matrix than the gels prepared with other salts. For color, the addition of sodium citrate resulted in an undesirable color of squid surimi gels, while the addition of sodium tartrate improved the whiteness of the surimi gel. The results showed that the quality of surimi gel was dependent upon the choice of heating method and the types of salt used. Sodium citrate and sodium tartrate could significantly improve the gel properties of squid surimi. This study provides reliable guidance for improving the overall quality of squid surimi gels.

Effects of transglutaminase enzyme on physicochemical properties of milkfish (Chanos chanos) surimi gel

Milkfish is one type of fish that can be used as raw material for surimi. However, previous research indicated that the quality of surimi powder produced from milkfish needed some improvements in order to produce surimi with good texture and strength gel. The addition of microbial transglutaminase (MTGase) enzyme is expected to produce surimi with better gel characteristics. The research objectives were to determine the best enzyme concentration and reaction time in the formation of surimi gel and to determine the effect of enzyme addition on the physical and chemical characteristics of surimi gel produced. The research was divided into two stages: 1) preparation for making surimi, and 2) determination of enzyme concentration and reaction time for surimi gel formation. The research treatment consisted of two factors, which were enzyme concentration (0, 0.1, 0.3, 0.5 units/g of surimi) and reaction time (0, 30, 60 mins). The observation parameters consisted of yield, gel strength, whiteness, pH, water content, protein content, and fat content. The results showed that the best concentration of MTGase enzyme was 0.5 units/ g with a reaction time of 60 mins. The addition of transglutaminase enzyme gave an effect significantly on gel strength, whiteness, protein content, and fat content in the milkfish surimi gel produced.

Karakteristik Sensoris Chikuwa dengan Perbedaan Bahan Baku Surimi Ikan

Increased production of aquacultured freshwater fish, such as Pangasius pangasius, Oreochromis niloticus, and Clarias batrachus, wich have low commercial value as potential alternative raw materials for surimi. This study aimed to determine the sensory characteristics of chikuwa produced using different raw materials of surimi and increase the diversity of processed fishery products that are highly nutritious with recommended physical quality. This research used the randomized block design (RBD) method with three repetitions. The treatment used were the difference in raw materials of surimi, P1 (Pangasius pangasius), P2 (Oreochromis niloticus) and P3 (Clarias batrachus). Parameters in this research included physical analysis of surimi (gel strength), chemical analysis of surimi (protein content and moisture content), and chikuwa sensory analysis. The results showed that Pangasius pangasius had a significant effect on surimi gel strength, surimi protein content and surimi water content, but had no significant effect on Oreochromis niloticus and Clarias batrachus. Based on the chemical analysis results, all raw materials for surimi have met the standard of SNI 01-2694-2013 except for Pangasius pangasius surimi protein (11,94%). Different raw materials of surimi had a significant effect on the appearance, taste, color, and texture of the organoleptic test. However, it had no significant effect on the chikuwa aroma parameters. Chikuwa (P1) produced the best characteristics from an organoleptic.

Insight into the Effect of Ice Addition on the Gel Properties of Nemipterus virgatus Surimi Gel Combined with Water Migration

The effect of the amount of ice added (20–60%) on the gel properties and water migration of Nemipterus virgatus surimi gel obtained with two-stage heat treatment was studied. The gel strength and water-holding capability (WHC) of the surimi gel with 30% ice added were significantly higher than those of other treatment groups (p < 0.05). The addition of 30% ice was conducive to the increase of protein β-sheet proportion during heat treatment, exposing more reactive sulfhydryl groups. These promoted the combination of protein-protein through disulfide bonds and hydrophobic-hydrophobic interactions, forming an ordered three-dimensional gel network structure. Meanwhile, the increase in hydrogen bonds promoted the protein-water interaction. Low-field nuclear magnetic resonance analysis showed that more bound water was locked in the gel system, reducing the migration of immobile water to free water and finally showing better gel properties. When the amount of ice added was insufficient (20%), the gel structure lacked the support of immobile water, resulting in deterioration of gel strength. However, excessive addition of ice (>30%) was not conducive to the combination of protein-protein and protein-water, forming a large and rough gel structure, resulting in the migration of immobile water to free water and ultimately exhibited weak gel properties.