In milk based infant foods not enriched with PS, Zunin et al.
(1998) reported 7-ketositosterol contents as a marker of phytosterol
oxidation ranging between 5.8 and 115.8 μg/100 g of dried sample. In
another study by our group, POP contents from β-sitosterol, stigmasterol
and campesterol were determined in milk and cereal based infant
foods (García-Llatas et al., 2008), resulting in 7-ketoderivatives of
β-sitosterol>stigmasterol>campesterol. The total POP contents were
low (0.9–16.1 μg of POPs/100 g of sample), though these foodstuffs
were not enriched with PS. Unlike in the present study, the predominant
oxide was 7-ketositosterol, followed by α-epoxysitosterol.