Sugar particles and their role in crystallization kinetics and structural properties in fats used for nougat creme production

Palm oil-based fat crystal networks, such as nougat cremes, often show liquid oil separation during storage. To understand the relationship between oil separation and the underlying fat crystal network retaining trapped liquid oil, palm oil dispersions with different sucrose particle size distributions were generated. In particular, the interplay of particle dispersity, crystallization kinetics, and mechanical properties were studied. The effect of sucrose particles on crystallization kinetics and mechanical properties was compared to a modified lipid profile by adding either a tripalmitin-rich fraction (palm stearin) or hazelnut oil to palm oil. The particle addition increased the maximum rate constants from 0.272 min⁻¹ to 0.310–0.317 min⁻¹, whereas the effect of a modified lipid profile on crystallization kinetics was far more pronounced (0.472 min⁻¹ for stearin addition in contrast to 0.084 min⁻¹ in the case of hazelnut oil addition). However, sucrose was found to be a bound filler and fine particles, in particular, substantially increase structural properties by providing junction points when fats crystallize under quiescent conditions. Furthermore, the yield point (τ₀) was increased from 559 to 828 Pa by the addition of 5% fine particles to palm oil equal to the addition of 20% stearin.