Water-solid interactions: Case studies relating to the effect of anticaking agents, relative humidity, temperature, moisture content, and pH on the chemical and physical stability of deliquescent ingredients
Abstract
Powdered ingredients and products are commonly used in the food and pharmaceutical industry. The stability of these powders may be affected by a variety of conditions, including temperature, relative humidity (RH), light, oxygen, pH, and particle size. Premixes are often used in a manufacturing setting, and blended systems are less stable than their individual counterparts. Water is ubiquitous to the environment and can have an impact on both the chemical and physical stability of powder systems. Deliquescence is a first order phase transformation from solid to liquid state that occurs at a specific RH for various water soluble crystalline solids. Current research indicates that the onset of deliquescence leads to instability for a variety of individual powders and blends. Understanding how the environmental and formulations factors influence the deliquescence for powder systems is important for quality control. The general scope of this study was to (1) determine the effect of anticaking agents on the chemical stability, moisture sorption, and deliquescence RH for crystalline solids and blends; (2) determine the effect of initial moisture content and RH cycling on the chemical stability and color change of vitamin C; and (3) determine the relationship between temperature, solubility, and heat of solution on the onset deliquescence RH for individual ingredients and blends of deliquescent solids. All deliquescent ingredients were affected by the addition of anticaking agents over time, including vitamin C, sodium chloride, sucrose, fructose, and citric acid. RH cycling led to minimal changes in chemical stability. Changes in initial moisture content in vitamin C samples led to minimal amounts of chemical degradation in concentrated systems and complete instability in dilute solutions, while color change occurred at a faster rate than chemical degradation. In addition, mathematical models were utilized for complex blends of deliquescent ingredients to predict the deliquescence RH based upon temperature, solubility, and heat of solution. In conclusion, numerous factors affect deliquescence, leading to enhanced moisture sensitivity and reduced chemical and physical stability of powder blends. Careful consideration should be made when formulating powder blends and determining proper storage conditions to optimized product quality and enhance powder shelf-life.
Degree
Ph.D.
Advisors
Mauer, Purdue University.
Subject Area
Food Science
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