Alkyl chain length modulates antioxidant activity of gallic acid esters in spray-dried emulsions.

• We studied how phenolipid polarity affects antioxidant activity in dried emulsions. • Polar antioxidants (e.g., gallic acid) are not effective in spray-dried emulsions. • For both the surface and encapsulated fat, octyl gallate seems to be most effective. • Yet, dodecyl and hexadecyl gallates are both still relatively effective. • The onset of lipid oxidation occurs during the spray drying process. Lipid oxidation is a well-recognized issue in dried food emulsions, such as infant milk formula. Antioxidants can be used to mitigate this issue; however, their efficiency in such complex systems is far from understood. In this study, antioxidant polarity is varied through the alkyl chain length of gallic acid esters (0–16 carbon atoms) incorporated to O/W emulsions that are subsequently spray-dried. During processing and subsequent storage of the samples, antioxidants with more than eight carbon atoms are effective. Both for encapsulated fat and surface free fat, we observe a slight cut-off effect, meaning that beyond eight alkyl groups, a more nonpolar antioxidant is slightly less effective. Depending on the antioxidant polarity, lipid oxidation is faster either in the encapsulated or in the surface free fat. The insights obtained contribute to understanding lipid oxidation in low moisture food emulsions, and thus lead to effective antioxidant strategies. [ABSTRACT FROM AUTHOR]