Antioxidant properties of wheat mill streams

Knowing the quality of mill streams is very important for getting flours with improved quality. In the present work, 49 mill streams, obtained by milling common wheat with an industrial roller mill, were characterized in terms of phenolic content, antioxidant activity and iron content. The antioxidant activity was estimated using different methods: DPPH-radical scavenging, Trolox equivalent antioxidant capacity, and iron reducing antioxidant power. The break tailings and first tailings of the reduction passages had the largest contents of iron. The total phenolic contents (TPC) from flour streams ranged between 76.3 and 369 mg ferulic acid equivalent/100 g d.w. The highest TPC were obtained for the second fractions resulting from 1st and 2nd break rolls. The highest antioxidant activity was registered for flour streams collected from: the last two break rolls, the reduction rolls that process the tailings of the first three reduction passages and bran finisher. Trolox equivalent antioxidant capacity had the same trend as DPPH-radical scavenging activity. The highest iron reducing antioxidant power was found in the tailings of the reduction rolls. The knowledge provided by this study could be successfully applied for getting flour with improved antioxidant activity and iron content by mixing different types of mill streams.

► The mill streams' properties depend on the anatomical parts they come from. ► The break and first reduction tailings had the largest contents of iron. ► Flour streams from break and reduction rolls had the highest antioxidant activity. ► Tailings have higher total phenolic contents compared to sieved fractions. ► Results show the possibility of using underutilized mill fraction in flour mixtures.