Study On Characteristics Of Antler's Freeze Drying Process

As one of the precious local products in the northeastern part of China, antler is a kind of rare and famous traditional Chinese medicinal material, which can exert the function of tonification of the kidney, heart, and brain, as well as lengthen one's life. The blood of antlers, which can enrich people's blood, also has a calming, sedative effect. The traditional method of processing antlers usually adopts boiling, which drains away most of the blood and other liquid substances in antlers, therefore causes great amount of effective medicine ingredients to run away. However, the materials obtained through the vacuum freeze drying method are characteristic in their excellent color, aroma, and taste, as well as in the excellent preservation of nutritional components. Comparing with the traditional method, the new one improves the effective medicine contents of antlers, namely, enhances their medicine values. Hence the freeze dried antlers possess a higher economic benefit comparing with the dried antlers; therefore, the income of deer raisers will be increased considerably, which makes the perfection and popularization of this technique very urgent.This thesis studies the characteristics of antler's freeze drying process comprehensively in a combining method of experiment and theory. Firstly, in the experimental studies of freeze drying process, I measure the temperature of the eutectic point of experimental materials with a homemade measurement system, and ascertain the prefreezing temperature. Then I respectively select antler slices and a whole antler to make the vacuum freeze drying experiment, obtain experimental data as well as freeze drying curves, and analyze qualitatively the experimental condition in which antlers of high quality can be obtained. At last, I respectively use optical microscope (reflected lighting and diascoptic lighting) to observe the microscopic structure of dry antlers, and mark the diameters of pores as well as the distances between every two pores, which provide boundary conditions for model resolve.During the study on the theory of antler's freeze drying process, I first summarize the developing history and the current research status of freeze drying theory, and then, directed towards the structural characteristics of antler, establish the mathematic and physical model of freeze drying process. Through the application of boundary conditions and resolving model provided by experiments, I analogue the temperature distribution in the process of heat and mass transfer, which is in line with the experimental data by comparison. By establishing the model of heat and mass transfer, the heat and mass transfer theory of biomaterials'freeze drying process is enriched.During the study of developing the specialized equipment for antler's freeze drying, firstly, I find out the features of antlers:little moisture content which leads to little gross amount of water capture; a low-temperature refrigeration system; a large freeze drying laboratory as the whole antler needs to be frozen and dried; an alterable workpiece shelf because both the whole antler and the antler slices need to be frozen and dried. Then according to these features, the specialized equipment for antler's freeze drying is developed.In the end, this thesis tests the effective medicine ingredients of the freeze dried antler, and makes an analysis by comparing them with those acquired by the traditional processing method. Thereby it arrives at a conclusion that the antler acquired by the freeze drying method has a more excellent quality.