NDC'01

THREE-DIMENSIONAL MEASUREMENT OF ICE CRYSTALS IN FROZEN MATERIALS WITH A MICRO-SLICER IMAGE PROCESSING SYSTEM

Gab-Soo DO¹, Yasuyuki SAGARA¹, Mizuho TABATA¹, Ken-ichi KUDOH², Toshiro HIGUCHI²
1. Department of Global Agricultural Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo,
Yayoi 1-1-1 Bunkyo-ku Tokyo 113-8657, JAPAN,
dogabsoo@iml.u-tokyo.ac.jp
2. Department of Precision Machinery Engineering, Graduate School of Engineering, The University of Tokyo

Key words: Ice crystal, 3 Dimensional Measurement, Micro-Slicer, Image processing,

ABSTRACT

A novel technique has been developed for measuring the three-dimensional (3-D) structure and distribution of ice crystals formed in frozen foods and biological materials by using a Micro-Slicer Image Processing System (MSIPS). The system has functions to reconstruct the 3-D image based on the image data of exposed cross-sections obtained by multi-slicing of a frozen sample with the minimum thickness of 1 m and to display the internal structure as well as an arbitrary cross-section of the sample choosing observation angles. The size and distribution of ice crystals can be determined from the 2-dimensional quantitative information such as the periphery and area of the crystals. The effects of freezing conditions on the morphology and distribution of ice crystals were demonstrated quantitatively from the observations of raw beef stained by fluorescent indicator. The network structure of ice crystals about 100 m in cross- sectional size was observed mainly at intercellular space for the specimen frozen at a temperature of 15° , while that prepared at 120° showed the spherical crystals of 10<< 20 m in diameter within the cells. The 3-D image of the sample demonstrated that the growth of ice columns was restricted by the intrinsic structure of muscle fibers. These results indicated that the proposed method provided a new tool to investigate the effects of freezing conditions on the structure and then transport properties for the dried layer of the materials undergoing freeze-drying.