Research On The Key Drying Technologies Of Scallops

In recent years, the scallops were welcomed by consumers because of its high nutritive value, special flavor, storage stability and portability. However, the scallops were drying by traditional natural air drying in most of the areas at present. In order to improve the level of drying scallops, using the bay scallops as the raw materials to meet the domestic and international market demand in this paper. Studies of this paper are based on drying dynamics of scallops and the properties of dried scallops at different conditions. It is the trend of modern drying techniques, and it will give a processing standard to scallops industry. The effects of three drying methods on the physical, chemical and sensory characteristics were investigated in this paper. The results showed that:1 The drying dynamics characteristics and drying model of scallops were studied and constructed, respectively. The drying temperature influenced significantly on drying characteristics of scallops, the higher the temperature, the shorter the drying time is, the faster the drying efficiency is, and the down faster the moisture content is. It can be seen that the removal of moisture from the material is governed by diffusion phenomenon. The drying behaviors of the present study were best fitted with the Page model. Scallops studied in temperature range were more difficult to dry, the effective diffusivities for scallops varied from 2.45×10^-11m²/s⁵.36×10^-11m²/s, and the activation energy was found to be 12.58kJ/mol. Considering the rehydration quality of scallops and the drying efficiency, drying at 55℃was proper for scallops.2 The experimental study on the relationship among the operational parameters and the time or the energy consumption during vacuum freeze-drying was carried out on scallops. According to the methods of quadratic orthogonal experiment, the mathematical models of the time or the energy consumption with the material thickness, heating temperature and pressure of drying chamber were established by the Design-Expert statistical software by analyzing the effects of the three main influential parameters. The optimum conditions : material loadage is 101.59g, heating temperature is 45.29℃and drying chamber vacuum degree is 54.79Pa.3 Studied three drying methods how to influence the drying curve, water activity, shrinkage rate and rehydration rate of the drying characteristics. Hot air drying and vacuum freeze-drying drying rate was faster, the drying time was shorter, the water activity was less than 0.700. Except for lower hardness, the hot-air dried scallops showed better appearance, lower shrinkage rate and higher rehydration in comparing with naturally dried product.4 Studied the influence of three different drying methods of scallops in sensory characteristics. Scallops of the natural air and hot air drying were moderate intensity in hard, and tasted good. The color of scallops dried by vacuum freezing-drying was closer to not drying ones.5 In this paper, general nutrients （moisture, crude ash, crude protein and crude fat）, amino acids, fatty acids as well as mineral elements in edible part of scallops were investigated. Protein in the scallops by vacuum freezing drying was rich, the amino acids and fatty acids reached the highest level, and it had significant difference whit two other drying methods. Scallops of Vacuum freezing drying had higher nutrition than the ones dried by other methods.6 Aroma compounds of drying scallops were analyzed by different methods, respectively. Solid phase micro-extraction coupled with gas chromatography mass spectrometry （SPME/GC-MS） techniques was applied in isolation and identification of aroma compounds. As a result, volatile compounds in three scallops dried by different drying methods were identified at 93, 79 and 94, respectively. Acids, aldehydes, ketones, esters, alcohols, alkanes and a few other compounds existed in the volatile compounds. The test results showed that the different drying temperature can induce a significant difference in content and variety of arom components in scallops.In a word, the drying techniques were discussed theoretically and practically in this paper. The tests of processing parameters and quantity for the production of drying scallops had certain directive significance.