Influence of spray drying on the stability of food-grade solid lipid nanoparticles

This study investigated spray drying of food-grade solid lipid particles (SLN) and nanostructured lipid carriers (NLC) containing ω-3 fish oil. Stable SLN and NLC dispersions with tristearin as carrier lipid were formed by using a combination of Quillaja saponins and high-melting lecithin as emulsifiers. Our specific goal was to study the influence of four different spray drying inlet and outlet temperatures (T_inlet/outlet = 140-170 °C/65-95 °C) and two different maltodextrin types (DE 6 and DE 21) with different molecular weights as protective wall materials on the physical and polymorphic stability of the solid lipid particles. The results revealed that the low molecular weight maltodextrin DE 21 was a superior wall material in stabilizing the solid lipid particles. Moreover, the lipid particles spray dried at T_inlet/outlet of 140/65 °C exhibited the highest physical and polymorphic stability, whereas using higher T_inlet/outlet led to bigger particles which were more prone to polymorphic transition. This was also verified in a 71-day storage test. The findings were explained that by preventing the melting of the tristearin carrier lipid during spray drying, the crystallized lipid particles remained intact inside the amorphous maltodextrin layer and exhibited high physical and polymorphic stability. These findings are important for generating stable food-grade spray dried powders.