Industrial processing effects on chestnut fruits (Castanea sativa Mill.). 2. Crude protein, free amino acids and phenolic phytochemicals

Summary The aim of this study was to analyse the effects of industrial processing on the composition of proteins, free amino acids and phenolics in Castanea sativa Mill. fruits of 2 years. The Portuguese cultivars were Judia, Longal, Martaínha and Lada, and the European cultivars were ‘Spanish’ (Puga do Bolo) and ‘Italian’ (Viterbes). At all processing stages the fruits contained low contents of protein (4.1–5.4 g 100 g−1 d.m.). The essential amino acid Thr had the highest values (3.6–10.0 mg 100 g−1 f.w.), while the highest non‐essential amino acid was Asn (14.9–36.4 g 100 g−1 f.w.). Total phenolics (6.6–18.3 mg g−1 f.w.) were more significantly affected by the processing stage factor. In 2007 the gallic acid contents were more affected by the processing stage and interaction factors (cultivar × processing stage), whereas the cultivar factor had more of an effect on ellagic acid. Industrial processing has some negative effects, specifically reducing the contents of some amino acids.