9-5 |
Polysacchride stabilizers in frozen foods: Understanding their functionality through microstructural analysis |
H. D. GOFF, Dept. of Food Science, Univ. of Guelph, Guelph, ON N1G 2W1, Canada Polysaccharide stabilizers have been used in frozen food systems for many years, to slow down the process of ice recrystallization and structural changes during frozen storage. When this phenomenon proceeds, it negatively impacts water-holding properties of the product during thawing, and can also negatively impact textural characteristics upon consumption. Ice cream is one such product that utilizes polysaccharide stabilizers, but it is unique in that it is consumed frozen and hence the size distribution of ice crystals is of critical importance for textural quality. Understanding how these polysaccharides function to control ice crystal growth, however, has been challenging, but is of importance to both finding and assessing new ingredients and or modifications to existing food products. Polysaccahrides are well known viscosity enhancers in solution, which occurs through their structure and their ability to interact. Through microstructural analyses, two additional phenomena are evident in frozen systems, both of which are relevant to polysaccharide functionality. The first is cryo-gelation, an inter-molecular interaction induced by freeze-concentration which sets up an element of 3-dimensional macromolecular structure, and the second is incompatibility and phase separation with proteins, if present in the food system, which is also enhanced by freeze-concentration and adds a further element of structure. These three phenomena are all responsible for polysaccharide functionality in frozen systems. Various microscopic techniques can be used to explore their structure, including specific staining with light or transmission electron microscopy and the use of labeled polysaccharides and fluorescence microscopy.
Session 9, Function of carbohydrates in frozen and refrigerated foods
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