The fundamentals and consequences of water vapor-solid interactions
Date and Location
When (Date/Time)October 20, 2016, 4:00 PM - 5:00 PM
Where252 Erickson Food Science Building
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The interactions between food ingredients and water are critical components of food quality and shelf stability. Water is ubiquitous in the environment in which foods are processed, stored, and used and is the culprit in many physical and chemical changes that occur during storage. Understanding the basic mechanisms by which water vapor interacts with solids can provide insight into what can and cannot be controlled for a given food product, production, or storage scenario. An overview of the five water vapor-solid interaction mechanisms will be provided (adsorption, capillary condensation, deliquescence, crystal hydrate formation, absorption), including commentary on how much water might be involved in each mechanism and what might be occurring in complex ingredient blends. Phase diagrams of deliquescence and hydrate forming deliquescent ingredients will be discussed. We will then move to the manipulation of food ingredient architecture. Many food formulation and production practices lead to alterations in food ingredient architecture, particularly in miscible ingredient blends and when using unit operations that include rapid solvent removal or high shear conditions. While many ingredients are crystalline or partially crystalline, they may adopt an amorphous structure during food production. Amorphous structures are thermodynamically and chemically less stable than their crystalline counterparts but exhibit enhanced dissolution profiles and softer textures. Case studies of the amorphization of common food ingredients will be discussed in terms of formulation, storage stability, hygroscopicity/hygrocapacity, glass transition temperature, and intermolecular interactions.