Producing high-quality extra virgin olive oil

In the Paardeberg near Wellington, Slent Farms are producers of superior quality olive oil. Michela Sfiligoi and Attilio Dalpiaz spoke to Jay Ferreira about their successful operation.

Producing high-quality extra virgin olive oil
Harvesting starts in mid- to end-April, and extends into May.
Photo: Jay Ferreira
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In 2003, Italian winemaker, Michela Sfiligoi, and her then fiancé, Attilio Dalpiaz, bought the 170ha farm, Slent, in the Paardeberg mountains, just outside Wellington in the Western Cape.

They married shortly afterwards and soon turned their attention to farming olives.

Attilio has a degree in agriculture, and a great deal of experience in farming in northern and southern Italy, where he farmed olives on his family’s property. He manages the farm’s production, while Michela manages the overall marketing of their products under the brand, Ayama.

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“When we bought the farm, there were about 12 Mission olive trees behind the house, so we pressed the olives for oil,” recalls Attilio.

“In 2007, we planted 9ha to four different cultivars of olive trees, including Coratina, Frantoio, Leccino and Mission.”

From left: Attilio, Michela and farm manager, Callie Hefer.

They chose these varieties for their unique characteristics, and blending these varieties makes for interesting flavours.

“Commercial olive growing is still young in South Africa, which also makes olive farming exciting,” he adds.

Attilio explains that it is better to plant olive trees in winter, but they can be planted throughout the year if irrigation is available.

Soil preparation for olive production is similar to that of vineyards, and is extremely important.

“It’s not enough to dig a hole and plant the tree. We use a digger, and prepare the soil with plenty of chicken manure or organic material that will release nutrients. We plant the trees 6m x 6m apart, which is further apart than is usual for South African growers, who usually plant their trees 4m x 4m or 4m x 5m apart. When I plant again though, I may plant trees a little closer, at 6m x 5m, or 5m x 5m apart, now that I know how they grow on our farm.”

Three years after planting, Attilio discs the ground between olive tree rows and plants alternate rows of lupins and triticale to provide the soil with more organic matter.

“South Africa has 50% more ultraviolet (UV) light than Italy, so it’s important to put the organic matter into the soil so it can replace what is burnt and destroyed by the UV light,” he says.

The farm’s soil type is granite sand for the first 60cm to 80cm, with Malmesbury shale clay underneath.

Attilio plants alternate rows of each cultivar to promote cross pollination. This year, he will extend his olive orchard and plant Don Carlo and Nocellara del Belice, as these varietals are now available in South Africa.

To be classified as extra virgin, olive oil is required to have no more than 0,8% free acidity. This year, Ayama’s extra virgin olive oil achieved 0,18% free acidity.

“Eating olives and consuming olive oil is increasingly becoming part of the South African lifestyle as people realise the health benefits, and use olive oil to dress salads and pasta, and in cooking. The current local supply doesn’t keep up with demand.”

He and his team usually prune in winter until mid-October, and focus on pruning the inside branches to allow for the movement of air and light through the trees.

Irrigation and spraying
Olive trees are evergreen and need water only in spring and summer, so Attilio uses drip irrigation.

“We lay the pipe down the middle of the inter-row to encourage the tree to search for water. When the tree searches for water, it also absorbs the soil nutrients deposited by the lupins and triticale.”

Ayama olive trees are irrigated three or four times a year for four to six hours at a time.

“They don’t need much water because they use the extra water to make more leaves, not bigger olives,” explains Attilio.

He and his team spray the trees twice a year: once to control olive beetles and once to encourage olives to set.

“If it’s a wet winter season, we supplement with sulphur to keep mould away,” he says.

“Olive fruit flies (Bactrocera oleae) are also a pest, but we only spray the perimeter trees in the orchard with an organic spray. It contains molasses, which attracts the flies and they don’t enter the orchard. Olive flies don’t lay eggs at temperatures over 30°C, and we usually have a few hours a day during their laying season where it’s over 30°C, so this takes care of the problem. We also have afternoon breezes, which makes it difficult for olive fruit flies to live here.”

According to Michela, they have had problems with grysbokke and duikers eating the leaves, which slows the tree growth.

“We painted the tree leaves with cow dung for a few months, and the bokkies have since left the orchard alone.”

Harvesting and quality

“Only 10% of olive flowers will produce mature fruit, but it’s more than enough because the tree wouldn’t be able to support the weight otherwise,” says Attilio.

“Harvesting starts mid- to end-April and goes into May. Frantoio is the early variety and the first to harvest, then the Mission and Leccino, and lastly the Coratina.”

Harvesting is the most expensive part of olive production as everything is picked by hand.

“Last year, we had a yield of 3 000ℓ from 19t of olives grown on 9ha. But the yield could be double this when the trees mature.”

All olives turn black on ripening. Green, unripe olives are also pressed, and produce a sharp-tasting oil with a powerful aroma.

“The rule of thumb in olive oil production is that a third of the olives used must be green, a third black, and a third changing from one colour to another to achieve complexity in the oil.”

Michela says that in the area where they farm the volume of oil production is quite impressive. Their Coratina olives produce about 20% olive oil/kg. This means it takes 5kg to 6kg of olives to make 1ℓ of oil, which, says Michela, explains why extra virgin olive oil is expensive.

“Our olive oil is currently pressed for us, but that will change soon because we’re building a facility to do our own pressing.”

The sooner, the better
One of the secrets to excellent quality olive oil is to “pick and press immediately, because after olives are picked, the acidity content increases rapidly”.

This year, Ayama olive oil achieved 0,18% free acidity; to be classified as extra virgin, olive oil is required to have no more than 0,8% free acidity.

During pressing, the olives are crushed, and a centrifugal force separates the oil from the water. As oil is lighter than water, they separate easily during this mechanical process, and no chemicals are used. Olive oil (not extra virgin) is extracted from the pulp of the initial pressing, and chemicals such as turpentine are usually used during this process.

Future of olive oil
“For me, the future is pink [rosy], as we say in Italy, because more and more people are becoming involved in the industry, and the standards and regulations in South Africa are stringent,” says Attilio.

According to him, every oil certified as extra virgin is tested for chemicals and organoleptic properties. “South Africa’s regulation of olive oil is excellent; much better than Italy’s. Imported olive oils may be cheaper, but they are not likely be tested to similar high standards as locally produced oils.

“In 2017, we’ll make monocultivar olive oils to offer more choices to customers, so they can select the appropriate product for themselves. Olive oil pairings are another offering for the near future.”

Email Michela Sfiligoi at [email protected], or visit