Bioactive compound content, antioxidant activity, deoxynivalenol and heavy metal contamination of pearled wheat fractions.

Wheat kernels are rich in antioxidant compounds, that are mainly present in the outer bran layers and which are removed during milling. Unfortunately, several contaminants, e.g., mycotoxins and heavy metals, are also concentrated in the external layers. Pearling of 3 wheat varieties gave five fractions (each 5% of the original grain weight), starting from the outer layer until the inner kernel, designated as 0-5%, 5-10%, 10-15%, 15-20%, 20-25%, respectively. The remaining 75% of the inner kernel was also collected. Dietary fibre, free phenolic acids and total antioxidant activity decreased progressively from the external to the internal layers. However, the 5-10% fraction was richer in β-glucan content than the external one (0-5%). Heavy metals were only found in the most external fraction. Deoxynivalenol contamination decreased from the external to the internal layers: 64% of total contamination of kernel was found in the 0-5% and 5-10% fractions. The 10-15% kernel fraction offered the best compromise between high nutritional value and low contamination risk.