Polymorphism of Tristearin

Pharmaceutical active ingredients, fats, oils, metals, salts and many other materials can exist in different crystalline forms. This property is known as polymorphism. This article shows how polymorphous materials can be investigated by DSC using tristearin as an example.

Introduction

A large number of materials exhibit polymorphic behavior. Knowledge about the different polymorphs is important especially for active pharmaceutical compounds and in the food industry because the different modifications of an active substance can have different effects: in foods, different polymorphs influence the texture of a foodstuff. For example, six modifications of cocoa butter are known that melt between 17.3 and 36.3 °C. In dark chocolate, the cocoa butter is mostly present in high-melting modifications and in milk chocolate in lower melting modifications. As a result of this, dark chocolate and milk chocolate create a different feeling in your mouth (the so-called mouthfeel).

In this article, we describe strategies that show how polymorphism can be detected and investigated by DSC. Tristearin was measured as an example.

Vegetable fats and oils consist mainly of triglycerides of fatty acids. Tristearin is a simple triglyceride in which three stearic Tristearin (1 molecule) Stearic acid (3 molecules) Glycerol (1 molecule) acid molecules are combined with a glycerol molecule (see Figure 1). Three modifications of tristearin are known, which according to the scientific literature melt at 54 °C (α-phase), 63.5 °C (β'-phase) and 72.7 °C (β-phase) [1, 2].

_{Polymorphism of Tristearin | Thermal Analysis Application No. UC 512 | Application published in METTLER TOLEDO Thermal Analysis UserCom 51}