How to preserve and defrost tuna
April and May of each year are a good opportunity to taste the delicious tuna and also a good time to fish for tuna. After catching tuna, how to preserve the color, freshness and deliciousness of the fish? How to defrost frozen tuna?
Today, let’s share with you how to store and defrost tuna.
At present, the mainstream tuna preservation methods include chilling, freezing in cold sea water, and ultra-low temperature freezing.
1. Chilled tuna:
After the tuna is caught on the ship, it needs to be quickly slaughtered, bloodletted and eviscerated, and then the processed tuna is buried in ice and kept fresh. After waiting for the fishing boat to land, the tuna is further washed, boxed, and frozen.
Advantages: Keep the delicious quality of tuna to the maximum.
Disadvantages: Very high requirements for storage and circulation processes.
2. Cold sea water freezing:
After the caught tuna is rough-processed, it is always stored in recirculating seawater mixed ice at -20℃ to -30℃. After the caught tuna is rough-processed, it is always stored in recirculating seawater mixed ice at -20℃ to -30℃.
Advantages: The entire body surface of the tuna can directly contact the cooling medium, which quickly reduces the body temperature of the center of the tuna.
3. Ultra-low temperature deep freezing:
The tuna that has undergone the necessary treatment is quickly frozen using the on-board freezing device before freezing, and then immediately placed in the ultra-low cold storage equipped with the fishing boat for storage. Tuna must be kept in an ultra-low temperature environment, that is, below -55°C, from the time it is caught, processed into finished products, stored, transported, and reaches the consumer's table.
Advantages: Long preservation time, ensuring the nutrition and freshness of tuna for two years. This is the most common method on the market, and the cost is relatively low.
The thawing process is also very important to keep the tuna meat delicious. If the correct thawing method is not used, a large amount of juice will be lost, and the taste, color, texture, and nutritional value of the fish will change, which will affect the quality of tuna eating.
Common thawing methods for tuna include warm salt water thawing and air thawing.
1. Defrost in warm salt water:
① Add salt to the warm water at about 40℃, and the salt water concentration is about 3%.
② Put the frozen tuna pieces in warm salt water and soak for about 1-3 minutes.
③ Take out the tuna in the salt water, use a clean absorbent paper or towel to absorb the moisture on the surface of the tuna.
④ Wrap the tuna pieces with clean absorbent paper or towels, put them in the refrigerator compartment (0-4°C), about 30 minutes.
⑤ Take out the fish pieces from the refrigerator and cut them into pieces before eating.
2. Air thawing: divided into cold storage thawing and natural thawing.
① The cold storage thawing is to put the tuna in the 0℃ cold storage.
Advantages: It keeps the color of the tuna and the freshness of the fish very well
Disadvantages: It takes a long time and leads to the loss of juice to a certain extent.
② Natural thawing is to defrost the tuna that has been frozen at an ultra-low temperature at room temperature, and transfer heat to the tuna to heat up and thaw.
Disadvantages: Natural thawing because the medium temperature is relatively high, there is a risk of bacterial reproduction.