Large Icefish Processing Technology Part 2: Detailed Methods

II. Processing of Lightly Dried Large Icefish Products

The processing technology for lightly dried icefish products is simple and convenient for storage, and because this kind of processing can preserve the inherent flavor of icefish, it is more popular among consumers than salted dried products.

1. Processing workflow

Raw materials → cleaning → soaking in alum water → secondary drying → piling and cooling → packaging → storage

2. Key operation points

(1) Raw material handling: First remove miscellaneous fish, shrimp and other impurities, pour the icefish into a wooden barrel pre-filled with half a barrel of clean water, add a few drops of cooking oil, stir by hand for 2-3 minutes, and remove foam and mucus.

In rainy weather, fresh icefish must be soaked and washed in alum water of different concentrations after being taken out of the water to prevent spoilage and to speed up drying. However, treatment with alum water affects their quality and reduces the product yield. Therefore, the following three points must be mastered when soaking and washing with alum water:

① When the weather is good, sunlight is strong, and evaporation is fast, use little or no alum. The standard for the alum water is that it only needs to wash off the mucus from the icefish, and the tail of the fish must not turn white from the alum. The ratio of alum to water is 1:60. The alum water can be used three times. The first soaking must not exceed 1 minute, the second can be extended to 2 minutes, and the third can be extended to 5 minutes. After washing, dry in the sun.

② When the weather is cloudy, water evaporates slowly, so more alum can be used. The standard for the alum water is that the tail of the fish can turn white from the alum, but the body of the fish must not turn white. The ratio of alum to water is 4:60. The alum water can also be used three times, and the length of time is mainly determined by just enough for the fish tail to turn white from the alum.

③ In rainy weather, the air is humid and the fish easily becomes moldy. The ratio of alum to water is 12:60. Soak the icefish in the alum water until the whole body turns white, then after the weather clears, rinse with clean water and dry in the sun. This is generally used when it rains continuously for one to two days during the thunderstorm season.

(2) First drying: On the boat, spread the treated raw materials on fish-drying net racks and press gently and evenly, then dry in the sunlight. When drying the fish, spread them thinly and evenly to shorten the sun-drying time and speed up drying. After drying, collect them into the cabin for temporary storage.

(3) Second drying: After 3-5 days, dry them again in the sun on a cement yard. The thickness of the spread depends on the degree of the first drying. If the first drying reached 70-80 percent dryness, spread to a thickness of 6-10 cm; if it reached more than 90 percent dryness, spread to a thickness of 10-15 cm. After drying for 1 hour, turn them over. After that, to make the finished product dry evenly, turn them once every 10-15 minutes, and once every 5 minutes under strong sunlight, until they are completely dry.

(4) Drying standard: To judge whether they are thoroughly sun-dried, besides checking that there is no damp feeling when grasped by hand, take one icefish and place it flat on the separated middle and index fingers, then press the middle section of the fish body with the thumb. If it has become crisp and can be broken, or has white fracture marks, it is completely dry. Special attention should be paid during sun-drying not to overdry, otherwise it will easily break apart after packing.

(5) Packaging: Move the completely dried icefish into the warehouse and pile them on wooden boards. After one day and night, wait for the heat to dissipate and for them to cool completely before packaging. If packed while hot, they are easily crushed or may heat up and deteriorate. They can be packed in gunny sacks, 50 kg or 100 kg per sack. When packaging, press them tightly; otherwise, not only will the volume be large and difficult to handle, but the large gaps in between will easily absorb moisture and cause deterioration. They can also be sealed and packaged in plastic bags of different specifications. The finished product can be stored for more than half a year, and under refrigeration conditions, it can be stored for one year.

3. Product yield and finished product grading

The grading of finished lightly dried large icefish products is mostly based on empirical assessment. Grade I: strips and sizes uniform, no alum or light alum, fresh when sun-dried, no impurities, white in color at the time of purchase, later turning flesh-colored; Grade II: strips and sizes uniform, relatively heavy alum water, fresh when sun-dried, strips round and slightly curved, slightly yellow at the time of purchase, later turning yellow; Grade III: strips and sizes uniform, produced in rainy weather, heavy alum water, curved strips, with impurities, yellow at the time of purchase, later turning red-yellow.