Effect of cooking on free amino acid and mineral profiles of sweet chestnut (Castanea sativaMill.)

Abstract

Introduction . Chestnut represents one of the most important crops for the Portuguese economy. The most common consumption mode of these fruits is roasted or boiled. In this context, the major aim of our study was to evaluate the amino acid contents and the mineral composition of raw and cooked chestnuts. Materials and methods . Amino acids were determined by HPLC and minerals were determined by molecular absorption spectrophotometry, by atomic absorption spectrophotometry or by flame emission photometry. The most important Portuguese cultivars were evaluated: Aveleira, Boaventura, Cota, Judia, Lada, Lamela, Longal Padrela, Longal Soutos da Lapa, Negra and Martainha. Results and discussion . The cooking method significantly affected the total amino acid composition with contents in roasted samples 13% and 12 % higher than in boiled and raw chestnuts, respectively. Roasted chestnuts presented higher alanine, arginine, isoleucine, leucine, phenylalanine, threonine, tyrosine and valine contents than either raw or boiled chestnuts. Moreover, serine presented the highest content in raw or roasted chestnut kernels. Regarding the mineral composition, potassium (K) was the predominant macronutrient in the chestnuts, whereas phosphorus (P), calcium (Ca) and magnesium (Mg) were found in low contents. Cooking significantly affected the mineral composition, except for iron (Fe), copper (Cu), and manganese (Mn) contents. In general, calcium decreased upon cooking. K, Ca, Mg and B decreased with boiling. The present data confirm that cooked chestnuts are a good source of amino acids and minerals, both affected by boiling and roasting, which have been associated with positive health benefits.