Crystallization behaviour of binary fat blends containing shea stearin as hard fat.

Filling fats are used in bakery and confectionery applications. These fats are made up of complex mixtures of triacylglycerols (TAG). The crystallization, melting behaviour and polymorphic stability of fat blends are determined by the behaviour of the TAGs that they contain. Filling functionalities are influenced by their fat composition but also by the processing conditions used for crystallization. In this study, the crystallization behaviour of fat blends, all based on shea stearin as hard fat (which is high in 1,3-distearoyl-2-oleoyl glycerol (SOS)) combined with either sunflower oil, shea olein or rapeseed oil, were investigated by means of pulsed nuclear magnetic resonance (pNMR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Blends containing either 30 or 40% shea stearin combined with one of the soft fats were selected as they met the criteria required for filling fats. Under static isothermal conditions (at 10°C, 15°C or 20°C), a two-step crystallization was observed for those blends, which can be explained by polymorphic transitions from α-form into more stable forms. All the selected blends exhibited different crystallization mechanisms according to the TAG composition of the liquid phase and their complementarity with TAG from the solid phase. Practical applications: Results of this research are useful for the fat industry as they could help to develop new filling fats, based on shea stearin, with a reduced content of saturated fats, while maintaining the desired physical properties of such specific products. pNMR isothermal crystallization curves obtained at 10°C (A), 15°C (B) and 20°C (C) for binary blend made of 30% shea stearin and 70% sunflower oil (plain lines) and binary blend made of 30% shea stearin and 70% shea olein (dashed lines) and corresponding XRD pattern collected at the end of the isothermal period (4 h). A1, B1, C1: 30% shea stearin/70%sunflower oil; A2, B2, C2: 30% shea stearin/70%shea olein. [ABSTRACT FROM AUTHOR]