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J. P. SHIELDS1, Y.-C. Hung2, and M. A. Farmer1. (1) Center for Advanced Ultrastructural Research, Univ. of Georgia, Dept. of Cellular Biology, 724 Biological Sciences Bldg., Athens, GA 30602-2607, (2) Dept. of Food Science & Technology, Univ. of Georgia, 1109 Experiment St., 180 Melton Bldg., Griffin, GA 30223-1797 Understanding the structure-function relationship has long been recognized as an important tool for controlling and improving the quality of frozen foods. Various types of microscopes have been used to provide the image of food structure. Most of the early images were taken using standard techniques in light microscopy which suffered from having limited resolution. Major advances on food structural analyses were achieved after the advent of electron microscopy techniques. This presentation will first review some of the traditional methods for preparing frozen food samples for microscopy like fixation, dehydration, and coating. A low temperature scanning electron microscope (SEM) equipped with a cold stage can be used to observe frozen food in its original state. This technique is a useful tool for observing the effect of freezing method and frozen storage conditions on the structure of frozen foods. Other new advances such as environmental SEM to study ice formation, crystal ripening and sublimation; atomic force microscopy to study protein structure, and dynamic confocal scanning laser microscopy to study milk protein gelation are increasingly being employed by food scientists. In addition to advances in cold stage design for the low temperature SEM other techniques such as cryo-transmission electron microscopy, automated detection procedures to improve image contrast and create a 3D images, and freeze fracture techniques will also be discussed.
Session 28, Ultrastructural measurements in frozen foods
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