# Comparative Evaluation of Traditional and Controlled Drying Methods of Chestnuts (Castanea sativa Mill.): Impact on the Chemical Composition, Aromatic, and Sensory Profile of Flour

## TL;DR

This study compares traditional and controlled drying methods for chestnuts and their effects on flour quality, aroma, and nutrients.

## Contribution

The study provides a comparative analysis of traditional and controlled drying methods and their impact on chestnut flour's chemical and sensory properties.

## Key findings

- Traditional smoke-based drying enhances aromatic complexity but risks undesirable sensory notes.
- Controlled drying preserves bioactive compounds like polyphenols and ascorbic acid.
- Controlled drying retains fresh chestnut aroma notes while ensuring quality preservation.

## Abstract

Chestnut flour, obtained through drying and milling of Castanea sativa fruits, has evolved from a subsistence food into a sought-after niche product, appreciated for its naturally gluten-free profile, high starch content, and richness in micronutrients. Over the past decade, its demand has steadily increased due to consumer perception of the health benefits associated with chestnut consumption. As the market for chestnut flour expanded from small-scale to large-scale production, alternative methods to the traditional process were developed. Its distinctive aroma and flavor are strongly influenced by processing methods, which are the focus of this study. Two drying approaches were compared: a traditional smoke-based method (drying house named metato) characterized by a wood-drying method and a controlled laboratory process using a forced-air dryer that maintained a constant temperature of 40 °C. The impact of these methods on the physico-chemical composition, volatile organic compounds (VOCs), and sensory properties of the flour was evaluated using chemical, instrumental, and sensory analyses. The traditional method enhanced the flour’s aromatic complexity and typicity through the application of smoke, which has been demonstrated to generate volatile organic compounds (VOCs), such as guaiacol, furfural, and o-creosol, that are associated with the smoked aroma. Nevertheless, if not properly managed, it can lead to undesirable sensory notes due to excessive smoke exposure. In contrast, the laboratory-controlled process ensured better preservation of bioactive compounds—such as polyphenols (351 mg GAE/100 g dm) and ascorbic acid (322 mg/kg dm)—while retaining the aroma notes associated with fresh chestnuts. Optimizing processing methods may support the valorization of chestnut flour as a high-quality ingredient in the modern gluten-free and functional food market.