DRYING OF AQUATIC PRODUCTS

The principle of aquatic product drying and processing is to remove water to inhibit the reproduction of microorganisms, prevent the deterioration of aquatic products, and thus preserve them for a long time. In addition, the oxidation of aquatic products by oxygen from the environment is also related to the water content. There are many ways to dry aquatic products, but no matter which method is used, its basic process is to transfer heat to the raw materials and transfer moisture out of the product.

During the drying process of aquatic products, there is heat transfer and moisture migration, that is, drying includes heat and mass transfer processes. Drying can be natural drying or artificial drying. Natural drying methods mainly integrate sun drying and air drying. There are many methods of artificial drying, but the best method is hot air drying with a heat pump.

sun dried and air dried

Sun drying refers to the drying process using the radiation energy of sunlight. Air drying refers to the process of dehydration by balancing the water vapor pressure of moist materials and the water vapor pressure difference in the air.

The temperature of materials in the drying process is relatively low. Warm, dry and well-ventilated weather is best suited for drying. But drying requires a larger site. To reduce the loss of raw materials and reduce costs, drying should take place as close to or at the place of origin as possible. In order to ensure hygiene, improve the drying rate and utilization rate of the site, the drying site should be located in a sunny place, long lighting time, ventilated location, and away from livestock sheds and garbage dumps. The site is easy to drain and avoid contamination by dust and other debris. The characteristics of sun drying are simple equipment, simple operation, energy saving and low cost. However, due to the limitation of weather conditions, natural drying has many factors that are difficult to control (such as temperature), so it is difficult to produce high-quality products. At the same time, it needs a large sunny area and a large amount of manpower. In addition, it is vulnerable to dust, insects and other contaminants, as well as the invasion of birds and rodents, creating waste and unsanitary conditions.

The secret to drying fish

To properly dry fish or shellfish, low-temperature air drying is used. The cold air drying technique is used, with the aim of simulating a natural drying environment (low temperature, low humidity and high air velocity) similar to autumn conditions. The use of TROCKNNER drying equipment is recommended because the sanitary conditions are good and it can perform drying at constant temperature.

For example, for a production of 1000kg of cod, it is recommended to use the TROCK - FOOD 1000 model. The cod is stored below 18℃. Before drying, raw fish must be thawed, for this, it is placed in a thawing tank with water for 3 to 5 hours. After thawing, the body temperature of the fish is around -2 to 4 °C. Then the fish is cleaned and seasoned. Finally, it is ready to enter the drying chamber.

The priority in the cod or shellfish drying process is that it must be carried out at a constant temperature. It is necessary to control the oven temperature at approximately 21 to 25 °C and the relative humidity at 30%. The drying time of the fish fillets is set to an appropriate period according to the water requirements. Subsequently, the fish is packaged and shipped.

*Reference table

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The TROCK - FOOD 1000 model recommendation is just a practical example.

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