An Automatic Method Based on Fiber-Optic Sensing for the Determination of Slip Melting Point of Fats

摘要

A automated open capillary tube melting point method based on the two-channel fiber optic refractive index sensor was designed and applied to determination the melting point of fats. The technique employs one optical fiber head to detect the molten state of samples and another optical fiber to serve as temperature sensor. Principle of the method is that the relationship between the heating temperature and the refractive index of the simethicone is a straight line. The refractive index-time curve is recorded by the sensor, the abrupt change point of the curve indicates the melting point. Combination of the refractive index of simethicone-temperature curve and the refractive index of simethicone-time curve, the melting point can be obtained easily. The principle and design of the apparatus were introduced in detail. The apparatus has been successfully applied to the determination of melting point of some kinds of fats. The results obtained with this technique show good agreement with the results from Wiley melting point method, with lower standard deviation. The automatic method based on fiber optic sensing show its obvious development of the traditional open capillary tube method, with objective and automatic endpoint determination, good repeatability, accurate results.