Emulsifier effects on fat crystallisation

The effect of the addition of two emulsifiers differing in their molecular structure (mono and di glycerides and Tween 80) on the thermal behaviour of a bulk fat containing both solid and liquid components (75% coconut oil and 25% of sunflower oil) was investigated using differential scanning calorimetry (DSC). Different ratios of emulsifier to bulk fat were considered (emulsifier/bulk fat of 0.02, 0.05, 0.08, 0.1, 0.3, 0.6 and 1). Both the emulsifiers had an effect on the melting and crystallisation of the bulk lipid. Mono and di glycerides (MDGs), although crystallising independently of the bulk fat (i.e. the observation of the presence of independent melting peaks and enthalpies that were not dependent on the ratio of MDGs to bulk fat), were thought to act as templates for the crystallisation of the bulk fat, having an effect on the shape of the melting and crystallisation peaks. Tween 80, due to its structural properties (unsaturated carbon chain and large hydrophilic head) was thought to act as an impurity leading to the formation of less perfect crystals and a loosely packed lattice, resulting in less energy required to melt. Due to the bulk fat and emulsifiers used this work has relevance to the ice cream industry, and could have implications for the physical properties of ice cream, particularly partial coalescence during manufacture, meltdown properties, texture and sensory perception during consumption.