The auxiliary materials and additive ingredients added to the surimi products and the matching method are directly related to the flavor, taste, appearance, quality, and nutritional value of the product. The auxiliary materials referred to starch, oil, egg white, and so on. The additives include quality improvers, seasonings, food colorings, etc. These excipients and additives can be used in combination according to product types, quality requirements, market needs, consumer habits in different regions, and market prices. At the same time, special attention should be paid to their quality and an additional amount must meet the corresponding national standards.

1. Starch

The Characteristics of Raw Starch in Fish Balls:

Give the fish balls better elasticity, increase the viscosity, facilitate the molding, increase the whiteness, improve the taste, and reduce the cost.

Disadvantages of Using Raw Starch in Fish Balls:

The raw starch is retrograded, resulting in a bad taste during the shelf life. It has poor water retention, poor taste, and single nature, which cannot meet the various requirements of fish balls.

Theoretical Basis of Modified Starch Applied to Fish Balls:

In order to improve the properties of starch and expand its application range, physical, chemical, or enzymatic treatment is used to introduce new functional groups on starch molecules or change the size and particle properties of starch molecules, thereby changing its natural characteristics (such as gelatinization temperature, Thermal viscosity, and its stability, freeze-thaw stability, gel strength, film-forming, transparency, etc.), making it more suitable for certain applications. This starch that has undergone secondary processing and changed its properties is collectively referred to as modified starch. (Note: Because of the difference in the way of modification, degree of reaction, etc., the characteristics of the same modified starch are also different).

Fresh fish meat contains 72%-80% water, and most of the rest of the solid matter is protein. When the product is heated, the protein loses its ability to bind water due to denaturation, and starch can absorb this part of the water, gelatinize and form a stable structure. It can be seen that it is very important to select starch with good water absorption and a high swelling degree to ensure the water holding capacity of the product and improve the tissue structure.

Compared with other varieties, modified starch with special properties has a low gelatinization temperature. The two functions of protein gelatinization and starch gelatinization in the product are almost simultaneously carried out, and a small “pond” will not be formed inside. During the heating process, the meat protein is heated and gelatinized to form a network structure. There is still a part of the water in the mesh that is not tightly bound, which is absorbed and fixed by the starch granules. At the same time, the starch granules become soft and elastic, which can stick and retain water. The dual effect of surimi gel at the same time reduces the impact of the deterioration of surimi gel. Modified starch has a very high degree of swelling, strong water absorption capacity, and can retain the moisture in the meat and added. Therefore, the fishball products with modified starch are uniform and fine in the organization, compact in structure, elastic, smooth in cut surface, tender and palatable, and have strong water retention during long-term storage and low-temperature refrigeration.

2. Plant Protein

Vegetable protein is mainly used as an elasticity enhancer for surimi products. From plant protein raw materials, it can be roughly divided into two series: soybean protein and wheat protein.

In addition to its own nutritional components, soybean protein products also have thermal coagulation properties, fat dispersing properties, and fiber-forming properties. Soy protein solutions with near-neutral pH will gel when heated. Therefore, adding it to the surimi can enhance the elasticity of the product, and the general addition amount is 5%. When the pH value is above 6.5, its water retention capacity can reach more than 90%. It can emulsify fat in the form of oil droplets in water, and the lower the protein concentration, the higher the emulsification efficiency, and the stability of the emulsion is positively correlated with the protein concentration.

Types of Soy Protein:

• Defatted soybean meal: Use n-hexane, alcohol, and other solvents to remove fat from soybean meal, and then dry it.
• Protein Concentrate: Wash defatted soy flour to remove carbohydrates to increase protein content.
• Extraction of protein: the water extract of defatted soybean powder is heated and then spray-dried.
• Protein Isolation: The extracted protein is refined again to improve its odor, color, and good gelation performance.

Wheat protein, also known as active gluten, is a spray-dried product obtained by adjusting the gluten obtained by removing starch from wheat into acid and alkaline and then dissolving it. Wheat protein is practically insoluble in the water near neutrality, forming a very elastic new glue. The elasticity of this viscose is affected by pH and salt concentration. It shows its physical properties at around pH 6, and the gel strength is the highest at around pH 8. With the increase of salt concentration, its stretchability and pinching resistance increase, and it shows good physical properties at 3% salt concentration. Wheat protein can generally absorb 1 to 2 times of water and has coagulation or binding properties after heating. The heating temperature needs to be above 80 °C to enhance the characteristics of the product.

3. Fat and Oil

The oils and fats added to surimi products are mainly animal fats and vegetable oils added to make the products have a similar animal-meat flavor. When added to surimi, they enhance and alter the flavor, texture, and appearance of the product, making it refreshing, smooth, and soft. Fried surimi products have the functions of improving appearance, eliminating fishy odor, producing burnt yellow, preventing mold contamination, and improving product preservation. At the same time, there is also the problem of fat oxidation, which cannot be ignored in production.

4. Egg White

Egg white is an animal protein that is added to surimi products as an elasticity enhancer.

In the whole egg white, the outer watery egg white accounts for about 25%, the thick egg white accounts for about 50% to 60%, and the rest is the inner watery egg white and other ingredients. The freezing point of egg white starts at 56°C and completely solidifies at 80°C, which belongs to the irreversible degeneration of protein.

Frozen surimi is added with various concentrations of egg white: from the perspective of breaking strength, adding 10% whole egg white is the best, and adding 20% for sensory evaluation is the best. However, if the addition amount exceeds 20%, the elasticity enhancement effect will decrease, and there is an egg white taste. After the addition, the effect of the second heating product is more obvious than that of the first heating.

The elasticity enhancement effect of fresh whole egg white and frozen whole egg white is almost the same, but fresh egg white is better for chewiness and luster. The strengthening effect of fresh thick egg white and water-like egg white is not much different, but it is better than thick egg white. Salted egg whites containing 5% table salt are less effective and less white than frozen whole egg whites. The product with the addition of sterilized egg whites was less broken and dented than the addition of frozen egg whites. Dried egg white powder has less elasticity enhancement effect than frozen egg white, but higher whiteness.

5. Gelatin

Gelatin is a collagen protein obtained by heating and hydrolyzing animal skin, bone, cartilage, and other collagen substances. The dried gelatin obtained after degreasing, concentrating, drying and other processes is a colorless and odorless substance. Due to the lack of many essential amino acids, their nutritional value is not high. But the chain-like proteins of gelatin gel dissolve in hot water and can form a special network structure when cooled.

Gelatin can form a high-moisture gel and is used in various foods. It is also often used as a suspension and oil emulsifier, a dispersant for pigments and fragrances, and a brightener for products. The amount of gelatin added in surimi products is generally 3% to 5%, which can fill the gaps of muscle fibers, increase the gloss of the section, and is not easy to collapse when sliced. Moreover, the content of various taste-dissolving components and spices in the gelatin gel is uniform, and the separation phenomenon of taste is not easy to occur.

In general, gelatin swells in cold water. When the temperature is increased, the long-chain molecules of gelatin are dispersed in water to form a high-viscosity sol, and its sweetness increases as the temperature decreases. At concentrations above 1%, it loses fluidity and becomes an elastic gel. The transition temperature between sol and gel is generally: sol occurs when the temperature rises to 30°C to 35°C, and gel starts when the temperature drops to 26°C to 28°C.

6. Sugar

The application of sugar in the production of surimi, in addition to being used as a sweetener for seasoning, also plays the role of reducing salty taste, seasoning, antiseptic, removing the fishy smell, and relieving greasy. More importantly, it is used to prevent the freezing denaturation of fish protein in frozen surimi. Adding an appropriate amount of sucrose in the production of frozen surimi can reduce the freezing point of fish, reduce the freezing denaturation of protein, prevent the loss of water, and improve the quality of the product. Adding sugar to fish sausage can prevent the oxidation of sodium nitrite and play a role in assisting hair color.

Compared with sugar, sorbitol is more effective than sugar in preventing freezing and denaturation of fish protein, and the speed of denaturation is also slower.

Granulated sugar is generally used in surimi products, and the amount of added sugar varies from place to place, which must be paid attention to by the manufacturer. Generally speaking, my country has the habit of being sweet in the south and salty in the north. The amount of sugar added to the surimi products sold in the south can be controlled between 3% and 5% of the total amount of surimi, while the amount of sugar used in the products in the north is 1%~2%.