Evaluating the potential of chestnut (Castanea sativa Mill.) fruit pericarp and integument as a source of tocopherols, pigments and polyphenols

The chestnut fruit processing generates large amounts of residues as pericarp (outer shell; 8.9–13.5%) and integument (inner shell; 6.3–10.1%). These materials clearly have the potential as sources of valuable co-products. The analyses of the pericarp and integument of four Portuguese chestnut cultivars (Judia, Longal, Martaínha and Lada) revealed significant contents of total phenolics, low molecular weight phenolics (gallic and ellagic acid), condensed tannins and ellagitannins including castalagin, vescalagin, acutissimin A and acutissimin B. The integument tissues had the highest levels of total phenolics and condensed tannins. The most efficient extraction solvent for the total phenolics, total condensed tannins and low molecular weight phenolics (in Longal) was 70:30 acetone:water at 20 °C. The pericarp and integument tissues of the cultivar Longal were richest in gallic acid and castalagin. It is clear that these materials could be used for the extraction of valuable phenolics.