Multi-Step Fractionation of New High Stearic Sunflower Oils

Fractionation plays a key role in the manufacture of specialty fats, particularly when applied to tropical oils characterized by a high content of saturated fatty acids, such as palm and coconut oils. This technique is based on the selective crystallization of triacylglycerols (TAGs) with higher saturation, followed by separation of the solid (stearin) and liquid (olein) phases to obtain fractions with increased solid content. The approach has also been extended to sunflower oils enriched in stearic and oleic acids. Here, we further examine the fractionation of high-stearic sunflower oils. Newly developed oil varieties with elevated stearic acid levels (20 to 22%) and varying oleic-to-linoleic acid ratios were evaluated. Additionally, the feasibility of applying a multistep fractionation strategy, similar to that used for palm oil, was assessed. Fractionation was successfully achieved under all studied conditions, and the physico-chemical properties of the resulting fractions were analyzed. The novel two-step process increased stearin recovery to overall yields above 50%, producing two distinct fractions: a solid fat with progressive melting behavior, and a mid-fraction enriched in disaturated TAGs with a faster melting profile, both of which may offer promising applications in a wide range of food formulations. The implications of these findings for the design and implementation of future industrial-scale fractionation processes are discussed.