In surimi preparation engineering, product quality is affected by many factors. Carrying out the adaptive processing of surimi products and products is of great significance to the deep processing of low-value freshwater fish. This paper summarizes the research progress of such products in order to provide a scientific basis for further research.
1. Research Progress on Processing and Preservation of Surimi
Freshwater surimi has lower gelling properties. The compound processing of seawater surimi and low-value surimi is an important way to enrich the source of raw materials. The gel strength and salt-soluble protein of the mixed surimi prepared by adding tilapia to 60% mackerel, 60% sea bass, 40% golden pomfret, and 40% kite squid, respectively, were significantly improved.
Frozen storage is the most common preservation method for surimi products. In order to alleviate protein denaturation during storage, maintain good spatial conformation, and lead to protein physicochemical properties and gel properties, surimi, such as oligosaccharides, protein hydrolyzates, enzymolysates, polyols, and salts, can be added to the surimi. Antifreeze can inhibit protein freezing denaturation to a certain extent.
After the pollock surimi was salted, 5% fish oil was added to prepare emulsified surimi thermal gel, which could reduce the thawing loss and pressing loss during frozen storage. The average particle size of ice crystals in the emulsified thermal gel is smaller, and the effect of rapid freezing is more pronounced.
Under an ice temperature storage environment, with the prolongation of storage time, the cooking loss of silver carp surimi products first decreased and then increased, while grass carp and carp surimi products gradually decreased. decrease over time. Silver carp surimi products decreased significantly ( P ＜ 0.05). the TBARS value of the surimi increased with the prolongation of storage time, and storage at ( -1.5 ± 0.03) ℃ should not exceed 3 weeks. And in the storage process of grass carp surimi, the use of electron beam irradiation combined with vacuum packaging can significantly prolong the shelf life of the product, but it will have a negative impact on the oxidation and unsaturated fatty acids of the product.
Rinsing helps improve the safety of surimi products. Rinsing twice can prolong the shelf life of catfish surimi by 4 hours, and can reduce the fishy smell of surimi. At the same time, adding fishbone peptide (0.5%), chitosan (10%) + tea polyphenols (0.3%), Whey protein (12.5%) can improve the freshness of surimi, and fishbone peptide is better. Using sucrose ( 4% ), sorbitol ( 4% ), and sodium tripolyphosphate ( 0.2% ) as cryoprotectants, the shelf life of surimi catfish at (4 ± 1) ℃ could be extended to 6 d.
In the research on the thawing method of surimi, microwave thawing and radiofrequency thawing have higher thawing rates than the traditional air thawing method. However, the gel water-holding capacity and gel-forming ability of microwave-thawed surimi were poor, and there was no significant difference in gel water-holding capacity between air-thawed and radio-frequency thawed surimi ( P ＞ 0.05).
The processing of surimi products is one of the key development directions of freshwater fish with low economic value. Improving the processing yield of surimi is an important guarantee for realizing economic value. The use of pH-shifting technology can significantly improve surimi yield without damaging the gel properties of surimi.
2. Research Progress on the Application of Transglutaminase and Vegetable Gum
Keratin helps to improve the gel properties of animal proteins and can significantly increase the formation of non-disulfide bonds. Adding 5% keratin to the surimi, the gel structure of the surimi is more dense and uniform. However, while adding konjac gum to Alaskan pollock surimi, antagonism will appear when adding konjac gum. The braking force and breaking strength of the gel decreased with the increase of the proportion of konjac gum added.
Carrageenan (0.5%) and guar gum (0.1%) can significantly increase the gel properties of silver carp surimi gel in the study on the improvement of xanthan gum, carrageenan, konjac, and guar gum. Hardness, breaking strength, gel strength, and whiteness, are suitable for product processing.
The content of sulfhydryl groups in the surimi products gradually decreased with the prolongation of heating time and the increase of heating temperature, indicating that the sulfhydryl groups formed disulfide bonds and cross-linked, showing better gel properties. With the same high-temperature treatment of 120 ℃, adding wheat protein or/and transglutaminase (TGase) to Alaskan pollock surimi can improve the gel strength of surimi products. When the two substances are added at the same time, the network structure is denser, and the gel strength of the product obtained by two-stage heating can be increased by 1 time.
Appropriate addition of TG enzyme (28.08 U/100g surimi) can reduce the gel temperature and gel activation energy, and significantly improve the gel strength and water holding capacity of bighead surimi. TG enzymes catalyze the cross-linking of myofibrillar proteins. As the degree of cross-linking increases, the surimi gel gradually changes from stickiness to elasticity and brittleness, and the flavor of the product also changes.
Regarding the application of TG enzyme in surimi products, the elasticity and hardness of the surimi gel of South Sea kite squid can also be significantly improved (100 U/g, 2%). Rinsing with CaCl2 solution (0.1 g/100mL) can enhance the gel strength of surimi cuttlefish. The addition of TG enzyme (1.0 g/100g) can enhance the gel strength and reduce the water loss rate; meanwhile, the pH value of the minced meat and the addition amount of sodium chloride also affect the water-holding capacity and gel strength of the surimi squid gel.
The activity of endogenous TG enzyme in grass carp surimi was affected by factors such as pH, temperature, ionic strength, activator, inhibitor, and frozen storage time of surimi. TG enzyme can enhance the cross-linking of actomyosin (the highest degree of cross-linking at 40-45 ℃), and the action intensity of exogenous microbial TG enzyme is better than that of endogenous TG enzyme. When the addition amount of TG enzyme was 1.5%, the gel strength of grass carp surimi was the largest, and the gel quality of potato starch, wheat starch, and corn starch was enhanced at the same time.
TG enzymes contribute to the formation of a highly dense, homogeneous horse mackerel surimi gel. When used in combination with other additives, it can significantly reduce the water loss rate of tilapia-sea bass mixed surimi and improve the gel strength of surimi products.
Regarding the thermoforming test of surimi, many research results show that the quality of products prepared by two-stage heating is better. At the same time, differences in steaming, boiling or microwave heating methods can also significantly affect the texture quality of surimi. Among them, the gel network structure of the product obtained by microwave heating is relatively good.
3. Research Progress in the Application of Protease Inhibitors, Proteins, and Starches
In the addition test of protease inhibitors, paramyosin was involved in the formation of the surimi gel of iris squid. Adding sodium pyrophosphate, bovine serum albumin, and potato flour can enhance the gel hardness, elasticity, and water holding capacity of surimi cuttlefish. And protein inhibitors and TG enzymes can jointly promote the formation of gel, and the more effective formulations are TG enzyme (2%), EDTA (250 mg/kg), sodium pyrophosphate (0.3%), bovine serum albumin (3%). %) and potato flour (3%).
Starch and modified starch are widely used in meat products because of their excellent functional properties. In surimi products, tapioca native starch, hydroxypropylated distarch phosphate, acetylated distarch adipate, phosphoric acid cross-linked starch and When the addition amount of hydroxypropylated starch was 10%, the sterilized surimi had better gel properties. It was manifested in the increase of gel whiteness and gel strength, especially the gel strength enhancement effect of hydroxypropylated distarch phosphate and acetylated distarch adipate was significant (P < 0.05). Tapioca native starch, hydroxypropylated distarch phosphate, and acetylated distarch adipate have significant effects on enhancing water holding capacity.
When sweet potato starch, corn starch, tapioca starch, and potato starch were added to the squid surimi, the gel strength of the product was increased by 49.08%, 20.77%, 26.46%, and 30.16%, respectively, and the water-holding capacity of the gel was enhanced. Among them, sweet potato starch is better. In addition to whey protein, soy protein isolate, soy protein concentrate and egg white protein increased the gel strength of surimi squid by 39.03%, 29.30%, and 35.82%, respectively. That is, some starch and protein products can improve the gel properties of squid surimi.
Whey protein has obvious biological activity and rheological properties and has a wide range of applications in the food industry. Different from the results of Wang Dongni et al., the most suitable forming conditions for the gelatinous surimi gel are 40 ℃ and 60 min. The addition of 5% and 10% whey protein concentrates enhances gel strength, maintains and improves gel elasticity, and inhibits deterioration at higher temperatures (50°C). The addition of 10% whey protein also improved the whiteness of the surimi gel (P < 0.05). When whey protein ( 10.22% ) compounded with calcium chloride ( 0.83% ) and modified starch ( 10.69% ) are used in golden pomfret surimi products, the gel strength and water holding capacity can be enhanced, but the gel whiteness reduce.
Egg albumin also significantly improved the gelatinous properties of silver carp surimi. However, egg albumin reduced the formation of surimi gels induced by microbial TG enzymes, and significantly reduced the strength and breaking strength of silver carp surimi gels. But does not affect the cross-linking of myosin heavy chain.
When ovalbumin was added to horse mackerel surimi, the breaking strength and concave degree of the gel increased significantly (P ＜ 0.05) with the increase of the addition amount (P ＜ 0.05), and the network structure of the gel was more consistent. The gel had the best gel properties when 1.0% ovalbumin was added, heated at 30 °C for 5 h, and then heated at 90 °C for 20 min.
When Kong Wenjun et al. added ovalbumin to Peruvian squid surimi, they also found that ovalbumin could significantly improve the breaking strength and gel strength of squid surimi (P ＜ 0.05). However, the addition of whey protein and soy protein did not significantly improve the breaking strength and gel strength of Peruvian squid surimi. At the same time, it was found that adding porcine plasma protein powder will reduce the breaking strength and gel strength.
It is also a non-muscle protein. When the amount of soy protein isolate in horse mackerel surimi is more than 1%, the degradation of surimi protein is significantly inhibited. When the addition of gluten was 10% and the addition of soy protein isolate was 5%, the gel properties of horse mackerel surimi reached the maximum. Has excellent burst strength, dent and gel strength, and improved water holding capacity. However, peanut protein concentrate will reduce the water holding capacity of the surimi, and the gelling properties of the surimi will also be reduced.
Rice dregs are a by-product of grain processing, but rice dregs contain more cheap protein. When rice dregs were added to silver carp surimi, various sensory indexes of surimi gel decreased significantly with the increase of the additional amount. After adding rice dregs protein, the gel strength, water holding capacity, TPA index, braking force, and breaking distance of surimi all increased first and then decreased. And when the addition amount is 1.0%, it is better, and the elasticity of surimi will decrease significantly when the addition amount is more than 1.0% ( P < 0.05). Rice dregs and rice dregs protein only play a filling role in surimi, thereby changing the texture properties of the gel.
Compared with rice protein, gluten protein is more effective in improving the gel properties of silver carp surimi. The addition of 3% gluten protein can promote the formation of a very dense three-dimensional network structure of silver carp surimi gel. The gel strength and water holding capacity are at a high level, but the whiteness of the surimi gel is slightly reduced.
4. Research Progress on the Application of Plant Fiber and Other Substances
Dietary fiber has an important physiological role. Meng Shuangshuang extracts soluble dietary fiber with different solubility and insoluble dietary fiber with different particle sizes from small bran by compound enzyme method and adds it to surimi. The gel strength of the surimi dietary fiber composite system was related to the amount of dietary fiber added. Appropriate addition of dietary fiber can improve the water holding capacity and hardness of the gel, and the effect of soluble dietary fiber is better.
Phenolic substances have different degrees of oxidative inhibition. Oxidized ferulic acid, tannic acid, catechin, and caffeic acid were added to the surimi crucian carp. When the addition amount is 0.20%, 0.05%, 0.10%, 0.05%, the surimi has higher gel strength and water holding capacity, the whiteness of the product will be reduced, and the microstructure will also change in different ways.
Chitosan has obvious antibacterial properties and is often used in the preparation of plastic wrap. When chitosan was added to silver carp surimi, the degree of deacetylation of chitosan had a greater effect on the gel properties of surimi. At 64% deacetylation, the gel strength gain was higher and the water loss was lower. The influence of molecular weight on the gel strength was small, and the texture properties of the gel improved with the increase of the additional amount. Adding 1.0% chitosan was similar to adding 4.0% starch.
Sodium glutamate and ethanol are often used to improve the taste and flavor of products. Adding sodium glutamate and ethanol to silver carp surimi, sodium glutamate (1.5%) or synergistic effect with sodium chloride (2%), improves the gel strength and breaking force of surimi. When the addition of ethanol increased to 0.6%, the hydrophobic interaction and the content of disulfide bonds in the surimi gel increased significantly, and the microstructure was dense, the pores were smaller and the distribution was uniform.
Perilla essential oil can increase the whiteness of grass carp surimi gel but has negative effects on gel strength, water holding capacity, and texture. When added gingerol or gingerol used in synergy with perilla oil, it has higher gel strength and water holding capacity. Fat oxidation, protein oxidation, volatile base nitrogen, and total microbial count were all at low levels in the product.
5. Research Progress on Other Processing of Surimi Products
Rinsing is an important process step in the processing of surimi products. The sarcoplasmic protein dissolved in the catfish rinsing process, recovered by isoelectric point precipitation, and added to the catfish ham slightly reduced the brightness of the catfish ham. With the increase of sarcoplasmic protein content (2% to 10%), the texture properties of ham showed a trend of first increase and then decrease. However, it can significantly increase the protein content of the ham and has the highest gel strength at 6% addition, which is better than the addition of TG enzyme or cornstarch samples.
Reducing the number of rinses can reduce the loss of protein while reducing the temperature of the rinse water can also reduce the degree of protein oxidation. When the mackerel surimi was washed with soda water, the braking force of the surimi gel gradually increased with the increase of the number of cycles of soda water. In the preparation process of golden pomfret surimi, the gel properties of the product prepared by rinsing 5 times (4 min each time), beating for 21 min, and two-stage heating were better. And adding 4.5% trehalose, 6.7% xylitol, and 1.2% complex phosphate for antifreeze treatment can delay the protein degradation and oxidation of surimi during frozen storage, thereby extending the shelf life of frozen storage.
In the preparation process of carp surimi gel, Li Haiping et al. rinsed 3 times with 4 times water to obtain the best gel quality. However, different from previous research results, it is believed that the quality of heating at 90 °C is the best. When rinsing pike surimi, rinsing with a CaCl2 solution can improve the gel properties of the surimi. At the concentration of 0.5%, the surimi gel prepared by a one-stage heating method at 100 °C for 20 min has a denser structure and a more orderly arrangement.
At present, minced products are mainly refrigerated or frozen products. The product has a short shelf life and has high transportation and storage costs. High-temperature sterilized products have higher shelf life and safety, but thermal processing will destroy the gel structure of surimi.
In the processing of silver carp surimi sausage, adding keratin and potato hydroxypropyl distarch phosphate can reduce the whiteness value of the surimi composite gel and strengthen the interaction with myosin heavy chain and actin. combined, which improved the stability, textural properties, and sensory quality of the surimi gel. And the best formula is 69.2% surimi, 26.1% water, 2.8% potato hydroxypropyl distarch phosphate, 1.7% salt, and 0.2% keratin.
Kedaran can improve the gel properties of surimi. In the process of fishball processing, the addition of keratin can significantly improve the gel strength, water holding capacity, and texture properties of fish balls ( P ＜ 0.05), and the effect is the best when the addition amount is 0.60%. At the same time, adding sage extract (0.1%), oregano extract (0.1%), and grape seed extract (0.01%) to the surimi can significantly reduce the fishy smell of fishball products. fishy smell.
In the process of surimi crushing, chopping will make the particle size of surimi first decrease and then increase. The optimal chopping parameters are 1 500 r/min rotation speed, 2 min air chopping, and 2-4 min salt chopping, but the texture and gel properties are still inferior to the beat-prepared products. The effect of different breaking methods on the gel properties of surimi is mainly reflected in the effect on protein denaturation and the effect on endogenous enzyme activity.
In addition to freezing and refrigerating the preservation of surimi, heat treatment is also an effective means of maintaining the quality of surimi products. With the increase in temperature (>100 ℃), the random coil damage of fish protein became more serious, and the myosin and actin changed. As the number of hydrogen bonds and disulfide bonds increases, the water holding capacity of the gel decreases. However, the damage caused by thermal processing will be alleviated after adding a water-retaining agent or process optimization.
Microwave heating is an effective technology for heating food bases. When the silver carp surimi was thermally processed by microwave alone and water bath microwave combined, the gel strength was 608.64 g cm, the water holding capacity was 83.64%, and the whiteness of the surimi was 608.64 g cm when heated by microwave alone ( 600 W, 60 s). The degree is 75.79. The gel strength was 627.37 g cm, the water-holding capacity was 85.37%, and the whiteness was 74.37 when the water-bath microwave combined heating ( 40 ℃, 1 h, 450 W, 60 s) was superior to the traditional two-stage water-bath heating. And the heating effect is more obvious when combined with a water bath and microwave.
When using ultrasonic-assisted strengthening, the power intensity of 0.49 W/cm2 and above can improve the gel strength and water holding capacity of silver carp surimi. 0.85W/cm2 works best.
The interaction between polysaccharides and proteins in the mixed gel was stronger under microwave heating conditions. Microwave heating for 5-10 min can improve the gel strength and water holding capacity of pollock surimi protein-konjac polysaccharide gel.
Ultra-high pressure can improve product quality and microbial safety. When the grass carp surimi is processed, the gel properties of the surimi can be improved. When the pressure exceeds 400 MPa, the gel properties of grass carp surimi are significantly higher than those of the heat-treated samples, the texture is more dense and uniform, and the hardness is lower. Ultra-high pressure can inhibit the activity of endogenous proteases that can cause the deterioration of surimi gel quality, and the effect is stronger with the increase of pressure.
In the analysis of the effect of lipids on the functional properties of surimi protein gel, Zhou Xuxia et al. added Camellia oleifera seed oil containing a higher content of unsaturated fatty acids, vitamin E, and tea saponin to the surimi. The gel strength, emulsion stability, and water holding capacity of surimi increased significantly with the increase of the addition amount (P ＜ 0.05), and the parameters were stable when the addition amount was 8%. At this time, the gel strength was 225.1 g cm and the juice loss was 2.60%.
When adding virgin coconut oil to yellow croaker surimi, the gel properties of surimi first decreased and then stabilized with the increase of virgin coconut oil (10%-25%). At 10% addition, there was no significant change in firmness and chewiness, but the whiteness of the surimi gel was improved and the free moisture content decreased.
γ-Polyglutamic acid can effectively protect the gluten to stabilize the network structure during the frozen storage period and improve the low-temperature stability of the gluten protein. When added to the surimi, the gel strength of the surimi can be significantly improved (P<0.05) when the addition amount is 0.54‰, and it has little effect on the whiteness value of the product. The effect of the addition amount of γ-polyglutamic acid, the heating temperature of the first stage, and the heating time on the gel strength decreased in turn.
In the preparation process of fermented silver carp surimi products, the endogenous TG enzyme mainly increases the gel strength of the product by enhancing the cross-linking strength of fish protein in the early stage of fermentation. The gel strength of surimi products decreased in the later stage, which was mainly caused by protein degradation under the action of endogenous enzymes. And its 2,2-azido-bis[3-ethyl-benzothiazole-6-sulfonic acid] diammonium salt (ABTS) clearance rate and iron ion chelating ability gradually increased. The clearance of 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) first increased and then decreased, which may be related to sulfur-containing amino acids and polypeptides with molecular weights between 1 000 and 5 000.
At the same time, glucose oxidase can promote the oxidative cross-linking of sulfhydryl groups of surimi protein to form insoluble protein. Different concentrations of glucose oxidase can enhance the gel strength, water-holding capacity, breaking strength, and braking distance of surimi products, and will not affect the whiteness. The optimum process conditions were heating at 40 °C for 30 min, heating at 90 °C for 20 min, and the addition amount of glucose oxidase was 0.5‰.
There are many factors affecting the quality of surimi products. The gel-forming ability of single source fish, especially freshwater fish, is poor. Through the optimization of process parameters and scientific compounding with exogenous excipients, one is to increase the degree of cross-linking of surimi protein, and the other is to cross-link with surimi protein, making the gel texture of surimi more uniform, dense, and stable.
In order to better carry out the processing of surimi products and the production of surimi products, it is necessary not only to control the product quality from the source of raw materials but also to do a good job in the adaptability research of parameters such as storage conditions and processing technology. Similarly, as an important part of the international food trade, the development of international quality standards for surimi and its products can provide more convenience for the output of products.
