Palm Oil Crystallization in the Presence of Sugar and Emulsifiers
This thesis explored the relationship between fat crystal network formation and rheology/texture in palm oil-based filling fats containing confectioner’s sugar and emulsifier. Filling fats are multi-component fat-continuous mixtures that are more complex than bulk fats due to the presence of dispersed particles that can alter fat crystallization and texture. The impact of palm oil type, emulsifier (lecithin or PGPR) and aeration on the crystallization, microstructural and mechanical properties of palm fat mixed at a 1:1 wt. ratio with confectioner’s sugar were evaluated over a period of four weeks. An increase in sample rigidity resulted from the addition of sugar to both palm oils. Conversely, there was a reduction in rigidity upon aeration. Addition of sugar did not impact palm oil melting enthalpy or solid fat content, demonstrating that addition of sugar did not greatly affect palm oil crystallization once present as a dispersion. The addition of emulsifier significantly reduced the viscosity of palm oil-sugar blends in the molten state. Bulk palm oil was seen to exist as crystalline spheroids 10-20 µm in diameter using microscopy. With lecithin present, there was an increase in the number concentration of spheroidal crystals but also a reduction in their size. PGPR reduced the extent of crystallization, however an increase in crystal size was observed. Addition of sugar greatly suppressed crystallization based on the difficulty in distinguishing fat crystals in the continuous phase of the palm oil-sugar blends. Overall, this study showed that the addition of sugar and emulsifier had a great impact the rheological attributes of palm oil. These findings help to strengthen the foundation iv necessary to optimize the crystallization of palm oil dispersions for industrial applications.