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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. [ABSTRACT FROM AUTHOR]

This is the first two year study with the major aim of evaluating the effects at the four sequential major stages of industrial processing (A-fresh, B-after storage during 3 months at ±0 °C and RH = 90%, C-after industrial peeling by flame or fire at 800–1000 °C, D-after freezing in a tunnel with a CO2 flow at –65 °C) on the contents of important nutrients in the fruits of four Portuguese (Judia, Longal, Martaínha and Lada) and two European (‘Spanish’–Puga do Bolo, and ‘Italian’– Viterbes) cultivars of Castanea sativa Mill. Fruits were found to contain significant contents of crude energy but low fat. In both harvest years, the interaction cultivar × processing step had the greatest influence on the starch contents while the cultivar factor had a much greater influence on the dry matter content. The fibre contents were more influenced by the processing stage for both harvests years. [ABSTRACT FROM AUTHOR]