[0010] Technical process of the present invention is described in detail as follows:
[0011] 1. The raw material of abalone is received, and the specification requires about 60g/piece (including shell weight).
[0012] 2. Raw material pretreatment:
[0013] ① Peel off the shell, remove the viscera, remove the mantle, and exfoliate the jaw plate (a component of the abalone mouthparts).
[0014] ②Use 8% refined salt to rub, wash, and scrub until the melanin around the feet is removed. The purpose of using refined salt is also to promote dehydration and convergence of the body as soon as possible, so that the protein can be solidified, which can prevent the shape from cracking caused by the next cooking process.
[0015] ③Cut pattern: Abalone's feet and side shells are rich in muscle mass, and the muscle mass is dense, the type of muscle scars and lines are not obvious, lack of filamentous muscle fibers, and the connective tissue formed between muscle proteins has extremely poor water permeability. This is the difference Due to the important physical properties of most fish and meat textures, it is not conducive to the evaporation and analysis of moisture in the traditional drying process. This process cuts the foot muscles and side shell muscles of the abalone in cross twill (grain size 0.3×0.3cm), so that the thickness of the layer to be dried of the abalone body muscles is less than 10mm, which is beneficial to heat and mass transfer in the drying process.
[0016] 3. Cooking, cooling, and neutralization: put the pretreated abalone body into 0.2% edible soda ash solution, submerge and cook for 10-15 minutes, which can soften the matrix in a certain procedure; The finished abalone is picked up, soaked in 0.4% citric acid solution with a water temperature below 8°C for 10 minutes, and neutralized until the pH value of the solution is 6.2-7.8; taken out, rinsed with clean water to remove excess residual liquid from the abalone body.
[0017] 4. Low temperature soaking, color protection: water temperature below 4°C/2Hr, 0.2% natural vitamin C + 0.05% tea polyphenols are added at the same time during the soaking process to prevent oxidative browning and ensure that the raw materials are bright and bright. Finally, rinse with clean water, pick up, drain, and spread on a plate.
[0018] 5. Freezing: The freezing rate for the first hour formulated in this program is 20-25°C/hr (ie 0.33-0.42°C/min), the total freezing time is 4 hours, and the temperature of the material after freezing is -24°C--30°C. When the water freezing ratio in the abalone matrix reaches more than 90%. This freezing scheme controls the reasonable rate of abalone matrix ice crystal formation zone, forms suitable tiny and stable ice crystals, and reduces the formation of large ice crystals. Such products will rarely be sponge-like after freeze-drying, and basically keep the same as before freezing. The physical structure improves the production efficiency on the premise of ensuring its reversibility and quality to the greatest extent.
[0019] 6. Vacuum freeze-drying in the drying chamber:
[0020] ①Basic principle of freeze-drying: The process of freeze-drying is divided into two processes: sublimation and analysis.
[0021] 1) For example, water at 0.01°C has a water vapor pressure of 610.5pa (4.58mmHg), and water, ice, and water vapor can coexist and balance each other. When the vapor pressure is greater than 611Pa, water can only melt into water first, and then vaporize. When the vapor pressure around the ice is lower than 611Pa, the ice can directly sublime into water vapor. Another example: ice at a temperature of -10°C, if the water vapor pressure around it is 400Pa, the ice can only begin to sublimate when the vapor pressure is lowered to less than 260Pa (the saturated vapor pressure of ice at -10°C). For ice with a vapor pressure of 103.5Pa, if its temperature is -30°C, it must be raised above -20°C (the ice temperature in equilibrium with the water vapor pressure of 103.5Pa) before the ice begins to sublimate. Therefore, the basic conditions for sublimation are: first, keep the ice from melting; second, the water vapor pressure around the ice must be lower than 610.5Pa. Ice sublimation needs to absorb heat. The sublimation heat of ice is different at different temperatures, but the difference is not large. Therefore, when sublimation is drying, it is necessary to continuously transfer heat to the ice crystal to provide the heat required for sublimation. But if the supplied heat is greater than the heat required for the sublimation of the ice, the excess heat will be absorbed as sensible heat, causing the temperature of the ice to rise. Ice melts when the temperature rises to freezing point, so even in an environment where the total pressure is well below the three-phase equilibrium point, it is possible for ice to melt if improperly heated. If the water vapor pressure on the ice surface is lower than the saturation vapor pressure of the ice, a part of the ice sublimates into water vapor, which increases the water vapor pressure. When the water vapor pressure increases to equal to the saturated vapor pressure of ice at this temperature, the ice and water vapor reach equilibrium, and the sublimation stops macroscopically. Therefore, there are two necessary conditions for maintaining sublimation drying: one is to continuously supply heat to the ice; the other is to continuously remove the water vapor on the surface of the ice, which needs to be equipped with a steam trapping device (composed of a condenser tube 4 and an ice melting tank 6) To remove the water vapor in the drying chamber 1, this technology adopts the technology of automatic alternate continuous water catching and melting ice so that the water vapor will never reach the saturated vapor pressure of ice. The sublimation drying is carried out in the drying chamber 1, and the material tray 3 is placed between the heating plates 2. The vacuum degree in the drying chamber 1 is controlled by the vacuum adjustment device 5. When the vacuum degree in the chamber reaches a certain value, the heating plate The temperature of 2 operates according to the preset freeze-drying temperature curve. The freeze-drying temperature curve is obtained through experiments. The maximum temperature should maintain the vacuum in the warehouse not exceeding the working vacuum range and the allowable value of the dry material temperature.
[0022] 2) After the ice sublimation is completed (the lowest temperature of the general material exceeds 0°C), the water content of the product drops to 15-40%. Freeze water. Aw is generally still greater than the optimum range, which provides conditions for the growth and reproduction of microorganisms and certain chemical reactions. In order to improve the storage stability of the product and prolong the shelf life, it is necessary to further analyze and dry to remove these moisture. After the analytical drying starts, due to the large temperature difference between the material and the heat source, the temperature of the material rises, and the unfrozen water in the material begins to evaporate and vaporize. When the temperature curve of the material is parallel or coincides with the heating temperature curve for a period of time, the heating is stopped. Break the vacuum and the freeze-drying is over.
[0023] ②Abalone vacuum freezing sublimation dehydration drying process parameters and curves:
[0024] Trap condenser tube 4 temperature: -35℃~-43℃
[0025] Pressure in drying chamber 1: 20~100Pa
[0026]Description of freeze-drying temperature curve: Heating plate 2 rises from 30°C to 95°C within 50 minutes (maintains for 1.5 hours), then drops to 90°C within 10 minutes (maintains for 2 hours), then drops to 85°C within 10 minutes ( maintain for 2 hours), then drop to 80°C within 10 minutes (maintain for 2 hours), then drop to 75°C within 10 minutes (maintain for 2.5 hours), and finally drop to 70°C within 10 minutes (maintain for 3 hours). When the moisture content of the material is less than or equal to 6%, it can basically meet the drying requirements.
[0027] One of the methods for judging the drying of the material is: when there is a relatively stable and close to parallel process between the temperature of the material and the temperature curve of the heating plate for more than 1 hour, at this time, the heating can be stopped, the vacuum is broken, and the product is released from the warehouse.
