Salted and dried fish is a kind of processed product that salted fresh fish first and then dried. There are many raw fish that can be processed into salted dried products, including sardines, mackerel, saury and other "prolific" fish species, as well as advanced fish species such as spiny fish, puffer fish and snapper. Japan's salted and dried fish processing products mainly include "fish tube" in which the whole fish body is salted and dried, and "fish shark" in which the abdomen or back is scraped and salted and dried. There are salty and dry products (suitable for drying: water content is about 35%), but recently, dried products with light salty taste and low dryness (called fresh salted products: water content is about 60%) have gradually increased. This is due to the technical progress of mechanical devices for processing, especially the popularization of dryers.

Raw material conditioning

Except for the direct salting of the fish body, the conditioning of other raw fish needs to be processed through various processes. For fish tube products with hidden fish, the internal organs are directly removed from the gills of raw fish, or the abdomen is cut open to reduce the internal organs. For fish products, except for fish with thin abdominal muscle layer (such as sardines), the back is usually cut open and the head is generally not removed.

wash

The conditioned raw materials are dipped in clear water or washed in slow running water, and the dirt attached to the raw materials is removed by washing, and the mucus and blood on the fish surface are removed as much as possible. In particular, dirty blood has an impact on the color and luster of the product, so blood removal must be very thorough.

Salting

Washing with water, draining and salting. Salting methods include dipping fish in salt water, mixing salt with solid salt sprinkled or coated on fish, and salting fish in shaking concentrated salt water, which is called semi-dipping method and so on. The purpose of salting is to make the salt penetrate into the fish body by soaking in salt water, at the same time, take away the water in the fish body, make the raw fish have suitable salty taste and unique taste, and prolong the storage time.

According to the species (characters, sizes) of raw fish, the requirements for products (salt content and dryness), appropriate methods and conditions are adopted for salting. Generally speaking, it is suitable for salted and dried fish by salting, and fresh salted and dried fish by dipping. The salt spraying method should be10 ~ 20% of the fish's weight, the concentration of salt solution should be 5 ~15%, and the salting temperature and time should be balanced.

puncture

When the size of the raw fish is small, several or even 20 fish can be connected by puncturing with bamboo sticks, wormwood cores and plastic thin sticks. Puncture methods include eye puncture through the eyes; Cheek puncture from gills through oral cavity; The needling method through the chin and so on.

Desalination

Salted raw materials and punctured salted raw materials are directly immersed in clean water or dipped and washed in slow running water to remove salt. When drying after desalting, in order to prevent the salt concentration on the surface of fish from being too high and the color and luster of products from deteriorating, the salted fish by immersion method and semi-immersion method should be washed with water before drying.

dry

The desalt and washed raw material are spread flat on that bamboo hat, or the puncture product is directly hung on the frame for drying. There are two drying methods: solarization method and mechanical method, each of which has its advantages and disadvantages. Mechanical method is widely used, and both of them are used properly.

The solarization method is a method of drying by using the sun and wind, which costs little for drying, which is its biggest advantage. However, in addition to having a large outdoor drying room, drying is easily restricted by meteorological conditions, which is its disadvantage. When the weather is bad, it is not easy to dry. Even if it is dried, the quality of the product is poor, and sometimes the fish body often deteriorates. Therefore, it is used more in the seasons of sun drying, general air drying and low temperature. The mechanical drying method has the advantage that it can be processed at any time, although the equipment and drying expenses are high. Dryers have hot air type and cold air type. The applicable temperature of hot air type is 25 ~ 30℃, and that of cold air type is about 20℃. It is ideal to control the temperature at 20℃ in high temperature season.

The drying process can be divided into the initial drying in which the water on the surface of the fish body is removed and the complete drying in which the water is completely removed after the fish body is continuously dried. The drying speed should be controlled faster at the initial stage, but not too fast during the complete drying process, so that the processing is ideal and the quality products can be obtained. Therefore, the hot air mechanical method is used in the initial drying process or the sun exposure method is used when the meteorological conditions are suitable, but the cold air mechanical method is used in the complete drying process.

In addition, when drying large-sized raw fish, if it is dried continuously, the result can only be that the surface of the fish is dry, and the products with uneven drying degree appear in quality. Moreover, the risk of corruption is likely to occur from the inside. In this case, when the drying reaches a certain level, the drying treatment should be stopped, and it should be left under natural conditions for some time to allow the water in the raw materials to distribute evenly before drying, so as to prevent the fish from being dried unevenly.