Alkylresorcinols in wheat and rye flour and bread

The alkylresorcinol (AR) content and relative homologue composition were determined in Norwegian flours and bread. The following average values for total AR content (μg/g dm) were found: wholegrain wheat flour available only to bakers (490) and to both consumers and bakers (710), refined wheat flour (36), wheat bran (3625), wholegrain spelt wheat flour (650), refined spelt wheat flour (80), wholegrain rye flour (972), refined rye flour (90) and rye bran (2753). The C17:0/C21:0 ratio was 0.1 for wheat and 0.8–0.9 for rye, confirming that it can be used to distinguish between wheat and rye. The AR content of Norwegian refined wheat flour was higher than that of Swedish, due to a consistently higher milling extraction rate in Norway. The content of AR varied from 27 to 2766 μg/g dm in hard bread and 21 to 548 μg/g dm in soft bread. The highest contents were found in bread with a high proportion of wholegrain flour and/or bran, in agreement with earlier studies. There was a good correlation (r = 0.91) and a high compliance between calculated and analysed AR levels in soft bread, confirming that AR can be used as a biomarker for wholegrain wheat and/or rye content in a cereal product.