Stearidonic Acid Soybean Oil Enriched with Palmitic Acid at the sn-2 Position by Enzymatic Interesterification for Use as Human Milk Fat Analogues

Stearidonic acid (SDA, C18:4n-3) enriched soybean oil may be added to the diet to increase intake of omega-3 fatty acids (FAs). Human milk fat has ≥60% of palmitic acid (PA), by weight, esterified at the sn-2 position to improve absorption of fat and calcium in infants. Enzymatic interesterification of SDA soybean oil and tripalmitin produced structured lipids (SLs) enriched with PA at the sn-2 position of the triacylglycerol. Reactions were catalyzed by Novozym 435 or Lipozyme TL IM under various conditions of time, temperature, and substrate mole ratio. Response surface methodology was used to design the experiments. Model optimization conditions were predicted to be 1:2 substrate mole ratio at 50 °C for 18 h with 10% (by weight) Lipozyme TL IM resulting in 6.82 ± 1.87% total SDA and 67.19 ± 9.59% PA at sn-2; 1:2 substrate mole ratio at 50 °C for 15.6 h resulting in 8.01 ± 2.41% total SDA and 64.43 ± 13.69% PA at sn-2 with 10% (by weight) Novozym 435 as the biocatalyst. The SLs may be useful as human milk fat analogues for infant formula formulation with health benefits of the omega-3 FAs.