Quality Control of emulsion processing and application
by NiuShangshen
With the emulsions’ physical properties, the information to verify the results with a reliable quality control (QC) process is extremely essential to ensure the dispersing & homogenizing processes are producing reliable results across batches.
Creaming is the phenomenon in which the dispersed phase separates out, forming a layer on the top of the continuous phase. It is notable that in creaming, the dispersed phase remains in globules state so that it can be re-dispersed on shaking. Creaming can be minimized if the viscosity of the continuous phase is increased. The easiest method is to put the emulsion on a shelf and observe it for creaming over time. A minimum acceptable shelf life can be a QC specification. Unfortunately, the price for this simplicity is that a poor batch might not be discovered until after the product reaches the customer. To overcome this, the creaming process can be accelerated by heating the emulsion or by centrifuging it. These results must then be related to a corresponding static creaming rate at room temperature. All these creaming-rate measurements are simple, but they are not precise.
Various factors can affect emulsion stability. Common issues with emulsion instabilities are coalescence, flocculation, creaming & breaking. Therefore, it becomes important to monitor its properties in real-time and make adaptive adjustments:
*Emulsifier concentration
*Oil/Water ratio
*Stirring intensity
*Mixing temperature
*Mixing time
Given that the viscosity of the emulsion is not a static parameter but is varying due to process requirement as well as from the processing itself, it is crucial to monitor and control viscosity during the complete processing cycle.
Creaming is the phenomenon in which the dispersed phase separates out, forming a layer on the top of the continuous phase. It is notable that in creaming, the dispersed phase remains in globules state so that it can be re-dispersed on shaking. Creaming can be minimized if the viscosity of the continuous phase is increased. The easiest method is to put the emulsion on a shelf and observe it for creaming over time. A minimum acceptable shelf life can be a QC specification. Unfortunately, the price for this simplicity is that a poor batch might not be discovered until after the product reaches the customer. To overcome this, the creaming process can be accelerated by heating the emulsion or by centrifuging it. These results must then be related to a corresponding static creaming rate at room temperature. All these creaming-rate measurements are simple, but they are not precise.
Various factors can affect emulsion stability. Common issues with emulsion instabilities are coalescence, flocculation, creaming & breaking. Therefore, it becomes important to monitor its properties in real-time and make adaptive adjustments:
*Emulsifier concentration
*Oil/Water ratio
*Stirring intensity
*Mixing temperature
*Mixing time
Given that the viscosity of the emulsion is not a static parameter but is varying due to process requirement as well as from the processing itself, it is crucial to monitor and control viscosity during the complete processing cycle.