Yingtai: Freeze-drying of Aquatic Products

Yingtai: Freeze-drying of aquatic products

Aquatic products, such as fish, shrimp, shellfish, etc., are favored by consumers for their rich nutritional value and unique taste. However, since aquatic products are susceptible to deterioration due to environmental influences, their preservation and conservation have become an important research topic. In recent years, with the continuous development of food processing technology, freeze-drying technology has been widely used in the field of aquatic products processing. The process of aquatic products freeze-drying technology mainly includes four steps: pretreatment, freezing, sublimation drying and post-treatment.

1. Pre-treatment

Firstly, aquatic products are cleaned, scaled and gutted to ensure product quality. Subsequently, the aquatic products are properly marinated and seasoned to enhance the flavor of the products.

2. Freezing

The pre-treated aquatic products are subjected to rapid freezing to convert the moisture into solid state. At low temperatures, the water exists as a solid inside the product, greatly reducing the chance of damage to other chemicals or life elements caused by the evaporation process of water.

3. Sublimation drying

The frozen aquatic products are put into the freeze dryer, and the ice is directly sublimated into gaseous water by lowering the pressure and heating, so as to achieve the purpose of dehydration. There is no need to add any other medium in this process, which can keep the original flavor and nutrition of the products.

4. Post-processing

After the drying is completed, vacuum packaging and other subsequent processing work is carried out to improve the preservation and shelf life of the product. *Some of the graphic materials are from the internet

With the increase in the production of surimi products, there is a growing scarcity of fish for raw materials. Shrimp meat is nutritious, delicious, the use of its protein gelatinization properties and the production of shrimp surimi products such as shrimp slipper, shrimp balls, etc., in recent years favored by consumers. However, the salt soluble protein content of shrimp meat is relatively low, and rich in endogenous proteases, will affect the gelatinization properties of shrimp meat, thus affecting the quality of shrimp products. Therefore, it is necessary to develop minced shrimp products to improve their gel quality. In addition, the effects of two drying methods, hot-air drying (HD) and freeze-drying (FD), on the lipid and color properties of shrimp from Vanabin and their mechanisms of action were investigated. It was found that freeze-drying reduced lipid oxidation more effectively than hot-air drying, resulting in lower primary and secondary oxidation products and acidity, and higher content of beneficial lipids such as triacylglycerol, phosphatidylcholine, phosphatidylethanolamine, eicosapentaenoic acid and docosahexaenoic acid. During the drying process, lipase and lipoxygenase were involved in lipid oxidation and hydrolysis reactions, and the freeze-dried treated shrimp had higher whiteness values while maintaining lower yellowness values and color differences. Correlation analysis revealed that lipid oxidation, astaxanthin degradation and the Meladic reaction jointly influenced the color change of shrimp. The principal component analysis showed that the freeze-drying technique exhibited superior quality deterioration control compared to hot air drying. In conclusion, freeze-drying is recommended to preserve the lipid nutrition and color of shrimp because it is more effective in controlling lipid oxidation.