Italian chestnuts, between tradition and innovation

Italian chestnuts have represented for centuries a multifunctional resource of inestimable value for the hilly and mountainous areas of the Bel Paese. The fruits of the European chestnut have guaranteed the sustenance of entire rural populations in Italy, providing a food that today stands at the crossroads between the tradition of ‘Made in Italy’ and product innovation, responding to the needs of increasingly attentive global consumers towards ‘plant-based’ and gluten-free foods.

This article explores the botany of the chestnut tree, the main varieties of chestnuts and marrons, their nutritional properties and enhancement opportunities that link ancient knowledge to modern technologies. To fully understand the value of the chestnut tree, it is essential to start from its biological characteristics and its millenary history, which binds it indissolubly to the Italian landscape and culture.

Botany, origins and distribution

The European chestnut, Castanea sativa Mill., is a woody plant with a tree-like habit belonging to the family of Fagaceae (IPFI sheet, Acta Plantarum, n.d.), as well as oaks and beeches.

Thetree reaches large sizes that can attain 35m in height and considerable diameters (Propetto, 2007). The famous ‘chestnut of the 100 horses’ – located in Sicily, in the Etna Park (Monte Etna UNESCO Site, n.d.) – has a trunk 22 meters in diameter and a crown 100 meters wide. Under normal growing conditions, the tree develops an imposing and straight trunk, characterized by smooth and shiny bark, gray-brown in color (Italian Museums, 2022).

The leaves are large and have a leathery texture. Their shape is characterized by a rounded-cordate base and a pronounced coarse dentation. Although young leaves are initially pubescent, they tend to become glabrous and shiny with maturation (Propetto, 2007).

The flowering

The chestnut is a monoecious species, meaning that on the same plant there are both male and female flowers, although distinct. The male inflorescences, called catkins, are long and yellowish, while the female ones are gathered at the base of the male catkins, inside a cup that will evolve into the burr.

Thepollination is predominantly anemophilous, meaning it is wind-driven. Pollen production is crucial for fruiting and depends on the type of male flower: long-stamened genotypes produce abundant pollen, while others, like many Italian marrons, are astaminate and therefore male sterile, requiring the presence of suitable pollinators in the chestnut grove.

The fruit

That of the European chestnut (Castanea sativa Mill.) is a composite fruit called trimosum, composed of several dry indehiscent fruits, the achenes (that is the chestnuts) enclosed in a spiny husk (pericarp) called burr. The burr, globose in shape and with a diameter varying between 5 and 10 cm, opens at maturity along four lines of dehiscence, usually releasing two or three achenes of color shiny brown. Each fruit is covered by a thin and leathery pericarp that protects the pulp, intended for human and animal consumption. Globose with a diameter of about 10 cm, it opens at maturity and disperses 2-3 indehiscent, brown, shiny achenes of 2-3 cm (Propetto, 2007)

Chestnuts and marrons, what are the differences?

From a botanical point of view chestnuts and marrons are fruits of the same species (Castanea sativa Mill.). Although the terms 'chestnut' and 'marron' are often considered synonyms in common language, the two products are clearly distinct from an agronomic point of view (Neri et al., 2010). The marrons are often produced by specific cultivars in specialized chestnut groves, while chestnuts are also collected from spontaneous woods (Alessandri et al., 2020). The fundamental difference lies in the number of seeds per fruit:

• chestnutsThe fruit, contained in the burr, is generally composed of multiple seeds (achenes), separated by an inner membrane (episperm);
• marrons. The fruit consists of a single seed of larger size, particularly prized for artisanal and industrial processing, as well as for fresh consumption (Massantini et al., 2021).

Origins and History

The European chestnut (C. sativa) boasts an ancient history. Paleobotanical studies have demonstrated its presence on the Italian and Iberian peninsula already during the last glacial maximum (about 20,000 years ago) (Massantini et al., 2021). Its cultivation spread in Western Europe thanks to ancient Greek and Roman civilizations. The Greeks began cultivating it both for wood and fruit. The Romans, while appreciating the fruit, mainly expanded its cultivation for the valuable timber, used in construction and barrel making.

During the Middle Ages, the chestnut became a primary food source, a true 'bread tree' for mountain populations (Alessandri et al., 2020). The very term 'chestnut' has deep historical roots, probably deriving from the Greek 'maraon' and already in use in Italy in medieval times (Massantini et al., 2021).

Main Italian varieties and their characteristics

TheItaly boasts a rich heritage of varieties and ecotypes of chestnut, the result of centuries of selection and adaptation to different territories. Below are described the main cultivated types.

Varieties of marrons

Highly valued for their superior qualities, they are the ideal choice for candying and the production of the famous marrons glacés, thanks to the flavorful pulp, the ease of removing the episperm (the inner skin), and the characteristic monoembryony (a single seed per fruit). Examples of key cultivars are:

• marrone di Castel del Rio (Emilia Romagna). Variety registered as PGI (Protected Geographical Indication) (Alessandri et al., 2020). It is considered among the most precious and well-known chestnut cultivars in Italy. This ecotype grows on schist soil and has shown a high protein content (Neri et al., 2010);
• marrone del Mugello (Tuscany) PGI. It is considered the ideal fruit to obtain high quality marron glacé. The chestnut of Marradi is an ecotype marketed under this denomination (Neri et al., 2010);
• chestnut of Valle Castellana (Abruzzo). Ecotype of the ‘marrone della Laga’ variety. Among the ecotypes analyzed, it showed the highest content of sucrose and fiber (Neri et al., 2010);
• red garrone. Vigorous cultivar suitable for higher altitudes. The fruits are medium-large in size. It is marketed with the “castagna Cuneo” PGI label and is suitable for both fresh consumption and candying (Pavese et al., 2022);
• black and gentle garrone. They are prized and widely spread cultivars, known for the quality of their fruits. Their main market is fresh consumption (Torello Marinoni et al., 2013).

Chestnut cultivars

In the repertoire of Tuscan-Emilian varieties, among Italian chestnuts, the cultivars mainly intended for flour production are:

• Carpinese (Garfagnana). Together with ‘Pontecosi’, ‘Capannaccia’ and ‘Morona’, it is used for “Neccio Flour of Garfagnana” PDO. Despite the small size (under 10 g), it showed the best nutritional compromise among local varieties, with high mineral content (P, K, Mg) and high total phenols content (TP) and antioxidant activity.
• Morona (Garfagnana). Also used for PDO flour. It has a lower sucrose content than ‘Carpinese’. Its total phenols content did not decrease after traditional drying unlike other cultivars (Lo Piccolo et al., 2020).

The cultivars widespread in Campania are instead the ecotype Rosso Salernitano (RSE), which produces good quality fruits with crunchy pulp and sweet taste. Its characteristic of late ripening (after the third week of October) makes it advantageous as it helps avoid frequent spring frosts. Other Campanian cultivars are Mercogliana, Rossa di San Mango, Verdola, Palummina (Roccarainola area) and Montemarano.

In Northern Italy, varieties with small-sized fruits are traditionally intended for flour production and dried chestnuts. This processing allowed the product to be preserved year-round. Among the best known are ‘Borgna‘, ‘Ciapastra‘ and ‘Pelosa‘. An important cultivar of Piedmont is the Pugnenga, together with the French ‘Savoye’, is one of the few cultivars of C. sativa known for its resistance to the gall wasp (Dryocosmus kuriphilus) (Nugnes et al., 2018; Aglietti et al., 2022).

Nutritional aspects

The chestnut (Castanea sativa Mill.) is a unique food, whose nutritional profile differs markedly from that of oily nuts, being rather similar to that of a cereal (Lo Piccolo et al., 2020; Guiné et al., 2023). This peculiarity derives from its composition, dominated by complex carbohydrates (starch) and generally low in fat, in stark contrast to walnuts, almonds or hazelnuts, which are instead rich in lipids and proteins (Massantini et al.; Guiné et al., 2023). The nutritional properties of chestnuts can be summarized as follows:

• the content of starch can vary from 38% up to 80% (Aglietti et al., 2022), or about 50 g per 100 g of dry weight in the raw fruit (Lo Piccolo et al., 2020);
• The energy value caloric content is relatively low and the few fats present (about 1%) are mainly polyunsaturated (MUFA and PUFA), beneficial for health (Aglietti et al., 2022);
• The protein content is moderate or relatively low (below 5%), but considered of high biological quality (Aglietti et al., 2022) due to the variety of amino acids (Massantini et al., 2021);
• the chestnut is also a good source of dietary fiber (Lo Piccolo et al., 2020). These fibers, being indigestible substances, stimulate the presence of beneficial probiotic bacteria and are useful for intestinal regularity (Guiné et al., 2023).

Chestnuts, although having nutritional characteristics similar to those of cereals, are naturally gluten-free (Bounous, 2005). Chestnut flour is therefore a valuable ingredient for preparing soups, cakes, and other foods intended for people with celiac disease and other gluten intolerances.

Chestnuts are also sources of vitamins – in particular Vitamin C, folates e pyridoxine (Vitamin B6) (Aglietti et al., 2022) – and of essential minerals such as potassium (K), phosphorus (P), and magnesium (Mg), as well as copper (Cu), iron, zinc, and manganese (Massantini et al., 2021; Aglietti et al., 2022). Potassium, phosphorus, and magnesium are considered abundant macronutrients in Italian chestnuts analyzed by Lo Piccolo and colleagues (2020).

Potential health benefits

Italian chestnuts (Castanea spp.), beyond the nutritional value, contain numerous bioactive compounds that suggest some health properties (Pavese et al., 2022). These fruits are rich in polyphenols, whose presence contributes to their antioxidant activity. In particular:

• catechins and tannins are the main molecules in the phenolic phytocomplex of the chestnut, often reaching 30–40% of the total phenols. They possess important antimicrobial, cardioprotective, and chemopreventive properties (Donno et al., 2023);
• the phenolic acids they typically represent 5–20% of the total phenolic phytocomplex. Chlorogenic acid and ferulic acid, in particular, are cited as variables explaining the variance in phenolic composition. They are characterized by anti-mutagenic, probiotic, cardioprotective and chemopreventive effects (Donno et al., 2023);
• gallic acid and ellagic acid they are the most important phenolic acids present in chestnuts, both raw and processed. Gallic acid is found in approximate amounts of 20–70 mg·100 g⁻¹ dry weight (DW), while ellagic acid ranges between 10–50 mg·100 g⁻¹ DW. They are considered important anticarcinogenic, antimutagenic, and antioxidant agents, particularly useful in preventing cardiovascular issues (Donno et al., 2023).

Favorable effects of cooking

The processes of cooking traditional can positively influence the phytochemical profile. In particular, boiling and roasting tend to increase the levels of gallic and ellagic acid (Donno et al., 2023).

From a biochemical point of view, the increase in ellagic acid is attributable to the thermal hydrolysis of endogenous compounds such as ellagitannins, while the increase in gallic acid results from the decomposition of tannins (galloyl esters).

The roasting, in particular, has proven to be the best method to preserve the polyphenolic content total in the varieties of Castanea sativa (Donno et al., 2023).

Cultivation in Italy

Chestnut cultivation in Italy is concentrated in the hill and mountain areas, at an altitude typically between 300 and 900 meters above sea level. The heliophilous plant prefers well-drained and sub-acid soils as it is particularly sensitive to water stagnation, which can promote the development of root diseases (Valli & Corradi, 2005).

The production of organic Italian chestnuts takes place in several Italian regions.

Organic agronomic techniques are based on sustainable soil management, on biodiversity conservation and on the use of natural products for plant protection. Preferring low-impact approaches and genetic solutions such as varietal resistance or the use of resistant cultivars or hybrids, like the Italian local ecotype ‘Rosso Salernitano’ (RSE).

Italian Tradition: regional excellences and markets

Italian chestnuts are deeply rooted in the gastronomic culture of the Bel Paese, with a wide range of products spanning from tradition to innovation.

Traditional products

The most classic consumption methods include chestnuts roasted (caldarroste), boiled e dried ('pilate'), that is, deprived of the episperm after drying. Some examples of traditional preservation and processing are:

• marron glacé (candied chestnuts). This confectionery product is internationally recognized as a refined sweet in the premium. The cultivars of the ‘marrone’ variety are best suited for candying (or marrons glacés) and for the production of highest quality, thanks to their excellent characteristics, such as the ease with which the episperm (the inner skin) is removed and the tasty pulp. Its origin is debated between the court of King Louis XIV, Lyon or Cuneo, dating back to the 16th century (Guiné et al., 2023);
• creams and preserves (chestnut purees). Chestnuts (or marrons) are traditionally transformed into Jams o purees. For example, in Portugal, chestnut preserves have been part of the culinary culture for centuries. These products belong to the category of ‘second transformation,’ which adds value to the semi-processed product (Bounous, 2005; Guiné et al., 2023);
• chestnut flour. Historically considered an essential resource of ‘poor kitchen,’ the flour is obtained by drying the fruits, often traditionally in the ‘metato’ (for about 30 days at 35–40 °C). Being naturally gluten-free, it is an important ingredient for celiacs. Some flours, like the Farina di Neccio della Garfagnana, have Protected Designation of Origin (PDO);
• bakery products and pastaItalian chestnut flour is traditionally also used to make baked goods such as bread, cakes, and cookies, in addition to pasta and polenta. In regional kitchens, you can find necci (simple chestnut flour crepes cooked on cast iron plates) and in Lunigiana, the lasagne bastarde (a type of fresh pasta. Dievole, n.d.).

Innovative foods based on chestnuts

The rediscovery of chestnut flour, being naturally gluten-free, has opened new market opportunities for the production of foods intended for celiacs, such as specialty bread, pasta, cookies, and even beer.

Among the innovative products, the use of chestnut flour as functional ingredient By probiotic fermented milk, where it improves the vitality of bacterial strains and the antioxidant capacities of the product (Aglietti et al., 2022), as well as fresh pasta (Guiné et al., 2023). It is also used in dry-cured meat sausages (dry-cured meat sausages), where it acts as a prebiotic, increasing dietary fiber and polyphenols (Aglietti et al., 2022).

Another area of great interest for sustainability is the enhancement of by-products of chestnut (such as shells), from which it is possible to recover high-value nutraceutical components, such as ellagic acid, through innovative processes like fungal fermentation (Guiné et al., 2023).

Italian market

Italian chestnut cultivation is characterized by strong fragmentation, with small and medium-sized companies. To compete effectively in the market, networking is essential. The example of the ‘Marrone del Mugello IGP’ consortium is not only a success story but also represents a strategic model that could be followed in other territorial contexts. This approach indeed allows to:

• enhance the product specificities linked to the territory;
• access premium markets, which recognize a higher price for certified quality;
• diversify sales channels and tackle the market with a structured and common strategy.

Guide to purchase and storage

For a quality purchase, it is useful to follow some criteria:

• size. Large fruits are ideal for fresh consumption (e.g. roasted chestnuts), while smaller ones are traditionally intended for flour processing;
• appearance. The pericarp (outer skin) must be shiny, intact, and without holes, which could indicate the presence of parasites.
• monoembryony. The marrons must have a single seed per fruit and an inner film that does not penetrate deeply into the pulp, facilitating peeling;
• certifications. The DOP (Protected Designation of Origin) and IGP (Protected Geographical Indication) marks are a guarantee of origin, quality, and compliance with a production specification.

Massantini et al. (2021) proposes the use of non-destructive analysis, in particular near-infrared (NIR) spectroscopy, to authenticate the origin and quickly assess the quality of chestnuts.

Storage

Fresh chestnuts are a highly perishable product due to their high water content (about 50%). To extend their shelf life, various techniques are adopted:

• ‘Curing" (or Hydrotherapy). It is a post-harvest treatment that involves immersing the fruits in cold or hot water (for example, at 50°C for 45 minutes). This process aims to eliminate larvae of the main fruit pests, such as the weevil (Curculio elephas), which may already be inside the chestnuts at the time of harvest, and to prolong the product’s shelf life.
• Drying. Allows long-term storage of the product in the form of dried chestnuts or flour.
• Freezing. A modern method that allows fresh product to be available throughout the year, once peeled.

For storage short-term, it is advisable to store fresh chestnuts in the refrigerator. After removing damaged specimens or those showing signs of pests, place the fruits in a paper bag or a breathable net, avoiding plastic materials which promote condensation. They can then be stored in the vegetable drawer. In this way, chestnuts maintain good freshness characteristics for about two or three weeks. Before cooking, let them rest at room temperature to prevent splitting during cooking.

Foreign markets

To understand Italy’s positioning, it is useful to look at the global production framework. According to FAO data from 2020, the main chestnut-producing countries in the world are: China, Spain, and Bolivia, followed by Turkey, Korea, and Italy (Massantini et al., 2021). This scenario highlights strong international competition, underlining the importance of focusing on quality, traceability, and the enhancement of varietal excellences to distinguish Italian production.

International buyers looking for high-end Italian organic excellence for purchasing a quality product can rely on the expert guidance of GIFT (Great Italian Food Trade).

Desirée Muscas

Cover credit: Chris Hoefliger (chrishoefliger) from Pixabay.com

References

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