Lennart Fries

Influence of Feed Composition and Drying Parameters on the Surface Composition of a Spray-Dried Multicomponent Particle

Surface properties of multicomponent particles produced in spray drying can be controlled by selective accumulation of specific components, which are present in the liquid feed, on the particle surface. Such modification of the surface composition can take place only before a solid shell forms on the particle surface. In this contribution, the influence of the concentration of surface active component on modifications of the surface composition is discussed. Based on results of single-droplet drying simulations, changes in the concentration of the surface active component at the solution-air interface are related to the composition of spray-dried particles.

Vitamin A degradation in triglycerides varying by their saturation levels

Vitamin A deficiency has a widespread occurrence globally and is considered as one of the worlds most serious health risk factors. Potential solutions to address this deficiency include dietary diversification or supplementation, but food fortification is generally accepted as the most cost-effective solution. The main issue with food fortification of this vitamin is related to its high instability in food matrices. Dilution of vitamin A in triglycerides is a natural and appropriate way to stabilize this compound. We show here that vitamin A palmitate stability increases with increasing concentration of triglycerides. Moreover, we found that vitamin A palmitate displays improved stability in more saturated oils. Using various temperatures, and Arrhenius plots of experiments performed at storage temperatures between 30°C and 60°C for oils varying by their saturation and crystallinity, we demonstrate that crystallization is not responsible for this phenomenon. Additionally, we show by centrifugation that vitamin A is preferably solubilized in the liquid phase compared to the crystalline phase, explaining that triglyceride crystallization does not stabilize vitamin A palmitate. It is proposed that unsaturated fats generate more oxidation products such as radicals and peroxides, leading to a quicker degradation of vitamin A.

Growth Agglomeration of Food Powders

This article introduces technical solutions applied in food, pharmaceutical, and chemical industries to enhance flowability and reconstitution of amorphous powders. Growth agglomeration describes the controlled buildup of porous structures by bringing sticky particles in contact with each other. Building on the material science describing glass transition, hygrosensitivity, and viscous flow, an overview is given on common methods to increase adhesion forces effectively by controlling local wetting, gas flow patterns, and powder movement in industrial systems. Three process concepts are compared with respect to the achievable product structure (size, instant properties, and tensile strength) as well as regarding throughput and cost: agglomeration during spray drying, steam jet agglomeration, and fluidized bed agglomeration. Examples are given from the food and beverage industry on typical applications of these processes.