Molding Research On A New Type Freezing Point Determinator For Food Materials

The freezing point is one of the important physical properties of fruits and vegetables, meat, eggs and milk and other food materials. With the development of the preservation technology of ice temperature, ice temperature preservation technology is an important preservation methods for food materials.The key of ice temperature preservation technology is to determine the freezing point of food materials. For many kinds of food materials, the determination of the freezing point will help to determine the appropriate storage temperature and freezing temperature, so the freezing point determination becomes an important technology.This thesis studies the relationship among conductivity, temperature and time through the determination of electrical conductivity by the freezing process on a variety of food materials and finds that when the material temperature dropped to a temperature below0℃, the conductivity will decline sharply. The temperature of the mutation point and freezing point value derived using the traditional method of temperature measurement are well matched, which proved the temperature when the conductivity drops sharply is the initial freezing point of food materials, so a new method of freezing point determination can be established, and this determination method is more accurate than the traditional method.By the choices of different freezing temperature,-21℃is determined as the freezing temperature of this study. This study takes the method of food materials freezing point determination through the material conductivity in the freezing process, so we need to determine the conductivity of materials in different temperatures, and warming constant of the conductivity meter is set to0.00%.Through the choices of different conductivity meter, the Chinese laboratory conductivity meter and the CON4000industrial conductivity meter can detennine the freezing point of food materials, because the CON4000industrial conductivity meter can match with a variety of electrodes, it is chosen for this study.Through the study of electrode and conductance constant, we find a multiple of between the electrode constant ranges from1to10, multiple of the measured conductivity values is between1and2. indicating that the conductivity of a materialsize is within a certain range. However, with the different electrode constants, the range of the electrical conductivity is different. When determining the electrical conductivity, we just select the appropriate measurement range of the electrode, and needn’t to select the electrode with too large electrode constant, otherwise, it will affect the conductivity values.Through the study of stainless steel electrodes and plate electrodes of different electrode constant can determinate freezing point of food materials. we propose a new type of three cylindrical electrodes. Such electrode can well maintain the organizational structure of the material when determining material freezing temperature, and makes the data more accurate.