Purified water-soluble fraction analyzed by UPLC was separated
into two fractions (Supplementary data 1). The major fraction was
eluted between 0.8 and 1.6 min and contained most hydrophilic
constituents. According to MS data, the eluted compounds corresponded
to oligosaccharides (di- to pentasaccharides), in accordance
with previous HPLC analysis of the crude extract (Fig. 3).
In addition to oligosaccharides, a peak corresponding to vanillic
acid was detected at around 1.5 min. The second fraction was
eluted around 5.9 min, and was greater in white than gold sesame
seed extracts. Mass data showed that this fraction contained
another phenolic acid, ferulic acid. Jeong et al. (2004) reported
the presence of both vanillic and ferulic acids in defatted sesame
seed meal methanolic extract. However, they specified that ferulic
acid was only detected in unroasted sesame seed extract, while
vanillic acid appeared in roasted sesame seed extract. As our samples
were obtained from sesame oil extraction byproducts, they
come from roasted sesame seeds because roasting is a key operation
in sesame oil preparation influencing its organoleptic properties
as well as its oxidative stability. Our results demonstrated thepresence of both ferulic and vanillic acids in the water-soluble fraction;
however, ferulic acid content seemed to be lower than that of
vanillic acid. The difference from previous studies could have been
due to differences in sample preparation and/or analysis method
used.