What Is an Acorn?

We can say that we enjoy Jamón Ibérico de Bellota thanks to one extraordinary fruit: the acorn. But do you know what an acorn actually is? Or what its properties and benefits are? In this article, we'll explain everything you need to know.

An acorn is the fruit produced by trees belonging to the Quercus genus, which includes the holm oak (encina), the tree most closely associated with the Iberian Peninsula. According to the Spanish Royal Academy Dictionary, an acorn is "the fruit of the holm oak, the oak and other trees of the same genus, such as the cork oak."

Before looking at the nutritional properties of acorns, it's worth noting that they are no longer a common part of our daily diet. However, historically they were an important ingredient in the Mediterranean diet. Today, acorns are mainly used to produce certain flours and liqueurs and, above all, to feed Iberian pigs.

Acorns

Acorn properties

Iberian pigs feeding on acorns in the dehesa

High content of oleic acid

One of the most remarkable characteristics of acorns is their high content of oleic acid, the same healthy fat found in extra virgin olive oil. Oleic acid is known for its positive effects on cholesterol, helping to reduce LDL ("bad") cholesterol while supporting healthy HDL cholesterol levels. Thanks to this, Jamón Ibérico de Bellota is recognised for its nutritional value and its place within a heart-friendly diet.

The benefits of acorns in the diet of Iberian pigs

An acorn-based diet, combined with the pigs' daily exercise in the dehesa and their unique genetic ability to infiltrate fat into the muscle, produces exceptionally juicy, flavoursome meat with its characteristic marbling. However, it's important to remember that Iberian pigs do not eat only acorns. Like all mammals, they are initially fed on their mother's milk until they reach around 23 kg. After weaning, they are fed specially formulated feed, following two different programmes:

Iberian pigs selected for the montanera

Receive a less nutrient-dense feed. Once they reach approximately 100 kg, they are released into the dehesa to begin feeding naturally on acorns. They produce Jamón Ibérico de Bellota.

Pigs that remain on the farm

Receive a more nutritious and vitamin-enriched feed, producing 50% Iberian Cebo Jamón.

What is the montanera?

To understand when Iberian pigs feed on acorns, it's important to know what the montanera is. The montanera takes place from mid-October until around the end of March, when acorns are fully ripe. An Iberian pig can only be labelled "Jamón Ibérico de Bellota" if it has fed freely on acorns throughout this period and in the famous Spanish dehesas.

When they first arrive in the dehesa at around 100 kg, they are released into the higher areas, where they walk long distances every day. This constant exercise is essential, as it allows the healthy fat from the acorns to infiltrate the muscle, creating the fine marbling that gives every slice of Jamón its unmistakable flavour, tenderness and juiciness.

Dehesa at sunrise

How to enjoy Jamón

3.5–5M

hectares of dehesa in Spain (Extremadura, Andalusia, Castilla-La Mancha, Castilla y León and the Community of Madrid)

100 m²

minimum dehesa required per pig to guarantee natural feeding and free movement

700K

maximum Iberian pigs finished per year, resulting in approximately 1.4M hams produced annually

Jamón Ibérico de Bellota

Jamón Ibérico de Bellota is one of Spain's most exceptional gastronomic treasures for several reasons. Firstly, it comes from the unique Iberian pig, a native breed found only on the Iberian Peninsula. Secondly, its exceptional quality is the result of an acorn-based diet enjoyed during the montanera within the unique ecosystem of the dehesa. At Enrique Tomás we offer two varieties: