Dr. Ran Drori

Dr. Ran Drori, assistant professor of chemistry and biochemistry, was awarded a research grant of $274,000 from the National Institute of Food and Agriculture of the U.S. Department of Agriculture to develop new imaging methods that will limit the damages of ice growth in food. This research grant is part of the competitive program named Agriculture and Food Research Initiative. When food is being frozen, ice crystals grow inside it and structural damages occur, which ultimately lead to decreased quality and taste of the food product. During storage of frozen food, ice crystals in the food product recrystallize, a process in which larger crystals grow on the expense of smaller crystals. These are the challenges of the effort to keep the high quality and taste of frozen food products. Controlling the formation and growth of ice frozen food may unlock new pathways to maintaining frozen food quality. Dr. Drori’s plan is to use two approaches: 1) using fluorescence microscopy and ice-binding proteins to identify how various natural molecules limit ice recrystallization in aqueous solutions, and 2) developing a new method of imaging ice growth inside frozen food using an Infra-Red thermal camera. News caught up with Dr. Drori to learn more about how these two approaches will achieve his goals.

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The grant is to help you develop two methods for imaging crystallization in food products. The first uses fluorescence microscopy and ice-binding proteins. What kind of information would this method give you? Using fluorescence microscopy, we can image special proteins that inhibit ice growth, called ice-binding proteins. We have labeled these proteins with fluorescence dyes so that each protein molecule carries around a dye molecule. In this way, we can measure how fast these proteins bind to ice and their density on the ice surface. These experiments will allow us to explain what factors affect ice recrystallization and how we should limit this damaging process.   The second uses an infra-red thermal camera. I thought ice crystals were cold. Ice is indeed cold, but when ice grows, it releases heat into the surrounding liquid, and studies have shown that thermal cameras are able to capture this small and local increase in temperature. The main challenge to image ice growing inside frozen foods is that the food sample is not transparent. The novelty of our plan is to use a special thermal camera that provides a temperature-based image. By controlling the temperature of the food sample while imaging it with the thermal camera, we will measure the exact temperature that each type of food product (e.g., bread, dough, meat, fish, vegetables and so on) freezes. In addition, we aim to measure the rate of ice recrystallization in the food product while it is stored at freezing temperatures. The ultimate goal is to use the knowledge obtained in the fluorescence microscopy experiments and to slow down the rate of ice recrystallization in food produces using ice-binding proteins.   If these two methods work, how much value would it bring to the frozen food industry? The success of this project will provide new information to the food industry and to the public. For example, we might discover that it is best to store food products at -10 degrees Celsius instead of at -20 degrees Celsius, which is the temperature of our freezer at home. Imagine the impact on energy costs if freezers will be manufactured to work at 10 degrees Celsius higher. The initial freezing process of food products might also be improved to achieve higher quality of frozen food and to limit the damage of ice growth in the food while it is frozen and during storage.