The main objectives of the present work were as follows: (a) to develop an analytical procedure to quantify free sugars on chestnuts based on green-chemistry principles and (b) to evaluate the effect of hot air convective drying (50 °C along 10 hr) on the carbohydrate profile of sliced chestnuts (Longal and Judia varieties). The analytical method allowed the quantification of several sugars in chestnut extracts, with low detection limits and good precision. In fresh, Judia variety had higher sucrose, fructose, and glucose contents than Longal, together with amylose. Nevertheless, when applying hot air convective drying to chestnut slices, a significant increase in fructose contents was observed with time, particularly after 10 hr drying in Longal variety. Nonetheless, a significant increase in glucose content was observed on both varieties, probably related to starch thermal hydrolysis. Practical applications: An environment-friendly methodology for free sugars quantification, based on ethanol/water extraction (green solvents), ion-exchange high-performance liquid chromatography separation with water as mobile phase, and evaporative light scattering detection, was developed. The method allowed the quantification of raffinose, sucrose, glucose, and fructose in chestnut extracts, with detection limits of 6 μg for sucrose and 0.3 μg for other sugars. Good precision was achieved with intra-day and inter-day coefficients of variation below 5%. Regarding chestnuts' drying, hot air convective drying might be applied to chestnut slices but it may induce modifications on the carbohydrate composition of the samples, particularly when long drying periods are applied, requiring some attention because it might induce both visual and sensory changes.
