Levels of pentanal and hexanal in spray dried nanoemulsions

•HS-SPME method was successfully validated for aldehyde quantification.•Pentanal and hexanal were significantly lower in powdered nanoemulsions.•Nanoemulsion powders had significantly lower porosity.•Partial replacement of lactose with sucrose may significantly reduce oxidation.

Lipid oxidation can adversely alter sensory and nutritional attributes of fats preserved in food powders. The aim of this study was to compare the extent of lipid oxidation in spray dried conventional emulsions and nanoemulsions. Powders containing lactose or lactose/sucrose (7:3) (57.9 g/100 g), sodium caseinate (12.4 g/100 g), sunflower oil (27.9 g/100 g) and water (1.8 g/100 g) were manufactured from control emulsions (D[4, 3] ∼ 1100 nm) and nanoemulsions (FGS ∼ 155 nm). A gas chromatographic headspace solid-phase microextraction (HS-SPME) method was validated and subsequently used to determine levels of volatile compounds pentanal and hexanal as indicators of lipid oxidation in powders stored over a 24 month period. Occluded air was significantly (P < 0.05) lower and interstitial air significantly higher (P < 0.05) in powders made from nanoemulsions. Levels of pentanal and hexanal were significantly (P < 0.05) reduced in powders made from nanoemulsions compared to those from control emulsions, due to their altered structure, lower porosity, and lower free fat. Partial replacement of lactose with sucrose may have also reduced pentanal and hexanal.