Industrial processing effects on chestnut fruits (Castanea sativa Mill.) 3. Minerals, free sugars, carotenoids and antioxidant vitamins

Summary The major aim of this study was to evaluate the effects of industrial processing on the composition of minerals, free sugars, vitamins and pigments in fruits of chestnut cultivars at four stages of industrial processing (A–fresh; B–after 3 months storage at ± 0 °C and relative humidity = 90%; C–after flame peeling at 800 °–1000 °C for 1–2 s; D–after freezing in a tunnel with a CO2 flow at −65 °C for 15–20 min) from two harvest years. Potassium and phosphorous were predominant in the fruits of all cultivars for both harvest years. Calcium, magnesium, iron, zinc and manganese were also present in the fruits. Fruits from both harvest years had a significant content of free sugars, with sucrose predominating, and these sugars were more affected by the processing stage. Significant levels of lutein, lutein esters, γ‐tocopherol and vitamin C were also found in the chestnut fruits. Fruit carotenoids and vitamin C significantly decreased during the industrial processing.