Direct and Accelerated Characterization of Formulation Stability

Abstract

Formulation of products as well as process and quality control is in need of fast and efficient measurement techniques of the state of dispersion products. We review the basics of experimental techniques of stability assessment of suspensions and emulsions, procedures of accelerated stability testing, and discuss the relationship between results of ''accelerated'' tests and the outcome under normal conditions of storage and usage (shelf life). Experimental results of the accelerated formulation testing are given with the focus on optical methods measuring stability based on space and time resolved changes of the volume concentration within the entire sample (STEP-Technology). In particular, acceleration of stability assessment acceleration by inclination and analytical centrifugation is demonstrated for diverse types of formulations. If the rate limiting step of destabilization is not sedimentation or creaming a combination with other established aging tests (temperature storage, freeze-thaw-cycles, physicochemical conditions, etc.) is suggested to reduce evaluation time.

Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

“…Several such conversions have been proposed in the literature. For example, Lerche and Sobisch 25 propose a method based on the initial separation velocity and the relative centrifugal force (RCF) at the meniscus, x max . The RCF is defined as the ratio of centrifugal acceleration to the gravitational acceleration.…”

“…Instruments are available to monitor transmission through the sample in time in a centrifuge. 25 The separation velocity under centrifugal force can be determined using these transmission profiles, and the corresponding Earth gravity separation velocity can be determined. However, recent studies have cast doubt on the accuracy of recovering Earth gravity settling velocities from centrifuge experiments.…”

Performance of whey protein hydrolysate–maltodextrin conjugates as emulsifiers in model infant formula emulsions

“…Stability of emulsions to creaming was determined at 23 C and 563 g for 8.5 h as detailed by Shimoni, Shani Levi, Levi Tal, and Lesmes (2013). Creaming velocity was calculated from front tracking profiles as detailed by Lerche and Sobisch (2011).…”

“…GmbH, Berlin, Germany). The principle of analysis by LUMiSizer has been detailed by Lerche and Sobisch (2011). Stability of emulsions to creaming was determined at 23 C and 563 g for 8.5 h as detailed by Shimoni, Shani Levi, Levi Tal, and Lesmes (2013).…”

Functionality-driven fractionation the need for mild food processing

“…Besides, no additional creaming was observed. Centrifugation can accelerate creaming, and is believed to be related to the long term storage stability of an emulsion (Lerche and Sobisch 2011). …”