Method for improving water-retaining property and texture quality of frozen tilapia mossambica through low-salt pickling treatment before freezing

Abstract

The invention discloses a method for improving the water-retaining property and texture quality of frozen tilapia mossambica through low-salt pickling treatment before freezing, and relates to the field of aquatic product processing. According to the method, low-salt pickling pretreatment is combined with a rapid freezing technology, so that the juice loss rate of the unfrozen tilapia fillets is remarkably reduced, the elasticity of the product is improved, and the quality problems of tissue looseness, juice loss and the like in the freezing storage process of the frozen tilapia fillets are effectively solved. The method disclosed by the invention is simple, low in cost and high in feasibility, and can be used for standardized and large-scale production; meanwhile, the quality of the existing frozen fish fillets is remarkably improved, the nutrient loss and the eating quality of fish meat are reduced, and the waste of aquatic resources is reduced. The frozen tilapia mossambica does not use other food additives except the flavoring agent salt, and the obtained frozen tilapia mossambica is safe, sanitary and convenient to eat.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic product processing, and in particular to a method for improving the water retention and texture quality of frozen tilapia by low-salt pickling treatment before freezing. Background Art

[0002] Aquatic products are a high-quality source of protein, and freezing is still the main processing and storage method for aquatic products. With the sharp increase in market demand for frozen convenient aquatic products such as frozen fish fillets and fish balls, the demand for high-quality processing technology for frozen freshwater fish products such as tilapia is becoming increasingly urgent. However, freshwater fish have poor freezing resistance, and frozen aquatic products have problems such as juice loss and rough taste after thawing. The edible quality and processing performance of frozen products have been greatly reduced, resulting in a waste of aquatic resources.

[0003] Tilapia is rich in nutrition, with delicious meat, white color and few bones. In 2023, the scale of my country's tilapia market will reach 31.3 billion yuan. The main tilapia processed products are frozen whole fish and frozen fish fillets. In 2023, the total export volume of frozen tilapia fillets will be about 25,600 tons. During the freezing and frozen storage process, the water in the muscle forms ice crystals. As the storage time increases and the temperature fluctuates, the ice crystals in the muscle continue to grow. The formation and growth of ice crystals cause muscle tissue damage, myofibrillar protein denaturation, decreased solubility, and a significant decrease in the quality of frozen products. During the processing and storage of frozen tilapia, problems such as juice loss, rough taste, and poor elasticity often occur, causing certain economic losses and waste of aquatic resources. Using different technologies to inhibit the formation and recrystallization of ice crystals in the muscle and improve the frozen storage stability of tilapia fillets will help improve the product's domestic and international market competitiveness. Summary of the invention

[0004] The invention provides a method for improving the water retention and texture quality of frozen tilapia with low cost and simple operation. The method aims to perform rapid freezing on the frozen tilapia after low-salt pickling before freezing, so that the morphology and distribution of ice crystals in the muscle are greatly improved, and the frozen storage stability of the frozen tilapia is significantly improved, so as to overcome the problems of loss of fish fillet juice and rough taste after thawing.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing, specifically comprising the following steps:

[0007] (1) Preparation of tilapia fillets: Stun fresh tilapia, remove the head, viscera, skin and clean it, and cut it into two pieces along the spine to obtain tilapia fillets;

[0008] (2) pickling of tilapia fillets: pickling the tilapia fillets in step (1) by wet pickling;

[0009] (3) Quick freezing of tilapia fillets: Put the low-salt marinated tilapia fillets into a plate freezer for quick freezing;

[0010] (4) Low temperature storage of tilapia fillets: storing the quick-frozen tilapia fillets for a certain period of time;

[0011] (5) Thawing of tilapia fillets: Take out the tilapia fillets after being frozen for a certain period of time and thaw them until the center of the tilapia fillets reaches a certain temperature.

[0012] As a preferred embodiment, in the step (2), the tilapia fillets in the step (1) are marinated at 4° C. for 1-10 hours by wet marinating.

[0013] As a preferred embodiment, in step (2), the mass concentration of salt in the pickling liquid used is 3%-15%.

[0014] As a preferred embodiment, in step (2), the weight ratio of the marinade to the fish fillets is 3:1.

[0015] As a preferred embodiment, in the step (3), the low-salt marinated tilapia fillets are placed in a -40°C plate freezer for rapid freezing for 4 hours.

[0016] As a preferred embodiment, in the step (4), the quick-frozen tilapia fillets are placed in a -18°C environment and stored for a certain period of time.

[0017] As a preferred embodiment, in the step (5), the tilapia fillets are taken out after being frozen for a certain period of time and thawed at 4° C. for 2-6 hours.

[0018] As a preferred embodiment, in the step (5), the tilapia fillets are taken out after being frozen for a certain period of time and thawed until the center temperature of the tilapia fillets is 0-4°C. DETAILED DESCRIPTION

[0019] The following is a detailed description of an embodiment of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0020] Embodiment 1:

[0021] After stunning a fresh tilapia, the head, viscera, skin and cleaning are removed, and the tilapia is cut into two pieces along the spine to obtain tilapia fillets. The tilapia fillets are marinated at 4°C by wet pickling, and the weight ratio of the pickling liquid to the fillets is 3:1. The low-salt pickling conditions are 6% NaCl solution-2 hours, 6% NaCl solution-4 hours, 9% NaCl solution-1 hour and 12% NaCl solution-0.5 hours, respectively. The NaCl content in the tilapia fillets prepared under the four conditions is 1.5%, which is called low-salt pickled fillets. The low-salt tilapia fillets are placed in a -40°C plate freezer for rapid freezing for 4 hours, and then stored at -18°C for a certain period of time. The fish fillets were taken out after frozen storage for 0 days (not frozen after pickling), 2 days, 14 days and 28 days, and thawed at 4°C for 2-6 hours until the center temperature of the tilapia fillets was 0-4°C. The changes in the quality of the frozen tilapia fillets, such as thawing loss, centrifugal loss, elasticity and cohesion, were investigated.

[0022] The method of the present invention can significantly reduce the thawing loss and centrifugal loss of frozen tilapia fillets during frozen storage, and improve their water holding capacity, elasticity and cohesion. Under the same frozen storage time, the thawing loss of low-salt pickled tilapia fillets is significantly lower than that of the untreated group, indicating that the method of the present invention can significantly reduce the loss of juice and nutrition during the thawing process of tilapia fillets and maintain a good appearance. After frozen storage, the centrifugal loss of low-salt pickled tilapia fillets is less than 10% of the control group. The elasticity and cohesion of low-salt pickled tilapia fillets are significantly increased, and still maintain high elasticity and cohesion after frozen storage.

[0023] Embodiment 2:

[0024] After stunning the fresh tilapia, the head, viscera, skin and cleaning are removed, and the tilapia is cut into two pieces along the spine to obtain tilapia fillets. The tilapia fillets are marinated at 4°C by wet pickling, the weight ratio of the marinade to the fillets is 3:1, and the low-salt pickling condition is 9% NaCl solution-1 hour. At this time, the NaCl content in the prepared tilapia fillets is 1.5%, which belongs to low-salt tilapia fillets. The low-salt tilapia fillets are placed in a -40°C plate freezer for rapid freezing for 4 hours, and then placed at -18°C for storage. The pickled and unpickled samples are divided into 5 parts on average, and 0, 1, 3, 5 and 7 freeze-thaw cycles are performed respectively. The freeze-thaw treatment is carried out in the following steps: the tilapia fillets frozen at -18°C are thawed at 4°C to a central temperature of 0°C, and then the fillets are returned to -18°C to be completely frozen. This is a freeze-thaw cycle, and a freeze-thaw cycle is performed every 3 days. Thawing loss, centrifugal loss, water holding capacity and textural properties of fish fillets were determined immediately after freeze-thaw completion.

[0025] The method of the present invention can significantly reduce the thawing loss and centrifugal loss of frozen tilapia fillets during repeated freezing and thawing, and improve their water retention and elasticity. With the increase in the number of repeated freezing and thawing, the thawing loss of uncured fillets increased significantly, but the thawing loss of low-salt cured tilapia fillets did not change significantly, and both remained at a low level. After repeated freezing and thawing, the centrifugal loss of low-salt cured tilapia fillets was more than 10% lower than that of uncured fillets. The elasticity of low-salt cured tilapia fillets increased significantly. After repeated freezing and thawing, the elasticity of low-salt cured tilapia fillets was significantly higher than that of uncured fillets. The results show that low-salt curing before freezing can improve the freeze-thaw stability of water retention and elasticity of tilapia fillets.

[0026] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing, characterized in that: The specific steps include: (1) Preparation of tilapia fillets: Stun fresh tilapia, remove the head, viscera, skin and clean it, and cut it into two pieces along the spine to obtain tilapia fillets; (2) pickling of tilapia fillets: pickling the tilapia fillets in step (1) by wet pickling; (3) Quick freezing of tilapia fillets: Put the low-salt marinated tilapia fillets into a plate freezer for quick freezing; (4) Low temperature storage of tilapia fillets: storing the quick-frozen tilapia fillets for a certain period of time; (5) Thawing of tilapia fillets: Take out the tilapia fillets after being frozen for a certain period of time and thaw them until the center of the tilapia fillets reaches a certain temperature.

2. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (2), the tilapia fillets in the step (1) are marinated at 4° C. for 1-10 hours by wet marinating.

3. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (2), the mass concentration of salt in the pickling liquid is 3%-15%.

4. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: As a preferred embodiment, in step (2), the weight ratio of the marinade to the fish fillets is 3:

1.

5. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (3), the low-salt marinated tilapia fillets are placed in a -40°C plate freezer for rapid freezing for 4 hours.

6. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (4), the quick-frozen tilapia fillets are placed in a -18°C environment and stored for a certain period of time.

7. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (5), the tilapia fillets are taken out after being frozen for a certain period of time and thawed at 4° C. for 2-6 hours.

8. A method for improving the water retention and texture quality of frozen tilapia by low-salt pickling before freezing according to claim 1, characterized in that: In the step (5), the tilapia fillets are taken out after being frozen for a certain period of time and thawed until the center temperature of the tilapia fillets is 0-4°C.