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Published March 2026

Facts about Extra Virgin Olive Oil

Miguel Abad is an olive oil expert. Born in Altura (Castellón, Spain), this olive tree and cycling lover is responsible for tasting many of the best extra virgin olive oils produced in Spain. We had the opportunity to interview him and ask him a few questions we had.

1. What’s the most popular variety of olives used to produce olive oil in Spain?

The main variety in Spain is Picual, found in Andalusia and the most widely planted by area.

2. How many kilos of olives are needed to produce one litre of extra virgin olive oil? 

It depends on what we’re looking for. If we’re really looking for a very high-quality oil, the level of extraction has to be lower. We may find that we need 8, 9 or 10 kilos, or if we want to have as much fat as possible, then 4, 4.5 or almost 5 kilos are enough for a litre. It depends on what we’re looking for. If we’re looking for very high quality, we need more kilos, but if we’re only looking for fat performance, we can make do with fewer kilos.

3. Why does olive oil have a bitter taste?

The bitter and spicy tastes are a consequence of polyphenol content. These polyphenols, which are antioxidants or natural preservatives, cause bitterness and spiciness to appear. And bitterness and spiciness are synonymous with quality. The higher the bitterness and the higher the spiciness, the more likely there is this fraction of phenolic compounds. And it’s obviously healthier, too.

4. In Greece, more specifically in Crete, oils have different degrees of acidity. Those with less acidity, such as 3%, are ONLY for salads. The others are for cooking. I’ve not seen this in Spanish or Italian oils. Do they also produce less acidic oil? I never see that written on the labels.

It has nothing to do with it. In Greece, there are no oils with more acidity or less acidity than in Spain. Acidity has nothing to do with taste. Acidity is a breakdown expressed in a certain percentage by dialysis of the major fatty acid known as oleic acid. So, this breakdown has nothing to do with the taste. We can find an oil that is bitter, spicy, or sweet with a low or a higher breakdown. That comparison is not like that. What does happen is that in oils derived from chemical treatment, or refining, you can add to the degree of acidity, which is what the refined oil bottling industry does. You can modify this level of acidity to the composition by adding oils of poorer quality or slightly better quality. But that’s not olive juice. The first thing is to be clear that acidity has nothing to do with aroma and flavour. It’s indicative of an initial deterioration of the fruit. There are no more acidic or less acidic oils in Greece. This is a result of the quality of the fruit and the same thing happens in Spain, Greece, Italy, and South Africa, where there are also olives.

5. I once had an excellent olive oil from Greece. It had a very nice hint of grass. Which olives are behind this? Does this note also exist in other countries?

In each variety the aromatic notes are different. In Greece, the most popular varieties are Koroneiki and Kalamata, but Koroneiki has very pleasant citrus and herbal notes. However, this doesn’t only happen in Greece or Spain. There are more than nine hundred varieties of olives around the world and all have volatile components and aromas that recall some fruits or others, and you can find olives with similar characteristics. In Spain, one of the varieties that has a very similar aroma and flavour to Koroneiki is the Farga olive from Castellón. Aromatically it is very similar. There are as many volatile components and aromas as there are varieties in the world. More than nine hundred.

6. How can I deduce the flavour of the oil from the variety of olive. Are there certain oils from olive varieties that I can try if I prefer mild, low-acid oils?

Of course. Simply by tasting the oil you can determine whether it’s more bitter, whether it’s spicier, or whether it’s more refined. This is a peculiarity that any of us can determine. My advice is to try a lot of extra virgin olive oils and use the ones that you find more pleasant. There’s no definite pattern to what’s better or not. In the end, it’s all about your tastes. As long as they’re an extra virgin, there are oils that are more bitter, more pungent, milder, or sweeter. And there are oils that have a very high aromatic intensity and oils that smell more of grass, green fruits, or red fruits. My advice is to taste various ones and even create your own private tasting selection. What’s more, each of them pairs or harmonizes very well with a certain type of food, so make sure you try a few.

Someone who tastes or who likes to taste oil is driven by curiosity. And to satisfy this curiosity, they try, smell, taste, and ultimately choose the oils that they like the most. They should always be extra virgin.

Written by Gonzalo Úrculo

Gonzalo Úrculo

Gonzalo es un "farmeneur". Como cofundador de CrowdFarming y agricultor, divide su tiempo entre la oficina y el campo. Además de la agricultura, disfruta leyendo y escribiendo sobre productos digitales y logística y discutiendo sobre su impacto en la cadena de suministro de alimentos.

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40 min

Apple walnut tart recipe

With the holidays just around the corner, our farmer Kathrin Wiest from Biohof Hund has shared one of her favourite seasonal recipes: an apple walnut tart passed down through generations in her family.Kathrin grew up spending weekends on her grandparents’ farm, where she helped with the hay harvest, milking the cows, harvesting vegetables, and discovering early on the importance of knowing where your food comes from. “Good food doesn’t begin in the kitchen,” she says, “it begins in the field.”This profound appreciation for the land followed her through her career in gastronomy and now into her work at Biohof Hund, where she combines her diverse background in gastronomy, organic farming, and horticulture.For Kathryn, working on the farm is more than just a job: “It’s a return to my roots,” she says, “a conscious choice for sustainability and regionality, and a step toward a future that truly makes sense – for my family, for our farm, and for society as a whole.”For Kathrin, this recipe captures values she grew up with: simplicity, seasonality, and a meaningful connection to the land.In this simple and delicious recipe, apples are arranged on top of a rich walnut cream and soft buttery crust: the perfect dessert to have around this winter.Save this recipe for your next holiday gathering!Apple & Walnut TartIngredients:  300 g spelt flour (plus a little extra for dusting) 120 g soft brown sugar Pinch of salt 2 medium eggs 200 g butter (130 g cold, 70 g softened, plus a little extra for greasing) 1 kg tart apples 2 tbsp lemon juice 150 g walnut halves 1 sachet vanilla sugar 50 g honey 80 ml double cream 1 pinch ground cinnamon Preparation:Place 250 g of the flour, 70 g of the sugar, a pinch of salt, 1 egg and the 130 g cold butter (cut into pieces) in a bowl. First mix with the dough hooks of a hand mixer, then knead briefly by hand until you have a smooth dough. Shape into a disc, wrap in cling film and chill for 30 minutes.Peel the apples, quarter them, remove the cores and slice into thin wedges. Toss with the lemon juice.For the filling, finely grind 50 g of the walnuts in a food processor. Beat 50 g soft butter, 50 g sugar, the vanilla sugar and a pinch of salt with a hand mixer until very creamy. Beat in 1 egg. Add the ground nuts and 50 g flour and mix briefly.Preheat the oven to 200°C (180°C fan). Roll out the chilled dough on a floured surface to about 30 cm in diameter and line a greased 28 cm tart or springform tin. Press the dough up the sides and prick the base several times with a fork.Spread the walnut cream over the base and arrange the apple slices on top. Bake on a rack set directly on the oven floor for 25 minutes.Meanwhile, for the nut topping, roughly chop the remaining 100 g walnuts. In a small saucepan, heat the honey, cream, cinnamon and 20 g butter, bring to the boil while stirring and simmer for 2 minutes. Stir in the walnuts.After the tart has baked for 25 minutes, spoon the nut mixture over the apples and bake for a further 10 minutes on the middle shelf.Leave to cool in the tin on a wire rack. Carefully remove from the tin and serve with whipped cream.

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