Olives are the earliest crop known to be cultivated by humans, having been grown and harvested for at least six thousand years.
In local gardens, their familiar grey-green foliage lends an immediate air of classical antiquity. But pressing and curing olives at home has become something of the past. For the adventurous foodie, though with access to productive trees, it can be a richly rewarding pastime.
You may already have a fruiting olive tree or two in your yard and wondered about how to bring it into production. Olive trees are not that picky—they’re easy to grow. If you don’t know what variety your tree is, some trial and error with harvesting and curing might be in order. Olive trees can be purchased in a wide range of sizes and prices and planted year-round.
Unlike many other fruits, the different colours that olives come in are due to the ripeness of the fruit, not the variety. Most olives are ready to harvest when the juice turns cloudy, at the “green ripe.” They ripen to an uneven reddish-brown, finally darkening to the “naturally black ripe” stage. Olives in this stage have a high oil content and can easily bruise. If harvested for eating, they need to be handled with care; handpicking is essential as damaged fruit will usually not survive the curing process.
For edibility, olives are processed, or “cured,” to remove most of the oleuropein, which is found in the leaves and fruit of the tree. Oleuropein is the main antioxidant in olives, but extremely bitter. Curing neutralizes this compound in different ways, each resulting in particular tastes and textures. The easiest and quickest way to cure olives at home is with water. In this method, the freshly picked olives are sliced or cracked to expose the interior of the fruit, they are immersed in water, which is changed once a day for five to eight days and then soaked in finishing brine with vinegar. You can even add flavours of your liking such as rosemary, chillies or garlic.
Brine curing is also a secure method where the olives are soaked in a water solution and pickling salt over several months. A fermentation process takes place during brining, which alters the flavour profile in distinctive ways. Dry salting is another simple option, resulting in a shrivelled olive that is slightly bitter and quite salty. Lye curing is perhaps the last frontier for home olive processing, but it needn’t be intimidating. Following some necessary precautions, lye will wholly and quickly neutralize the oleuropein in the olives, leaving a de-bittered olive with crunchy texture.
In addition to curing for eating or cooking, olives can be processed at home for their precious oil. Historically, the process relied on large stone grinding wheels drawn by livestock. Expensive grinders and oil presses may be purchased, but with a streak of “maker” inventiveness and experiments of others posted on YouTube as a guide, the necessary equipment can be rummaged or cobbled together for much less depending on the scale of the operation.
Whether the final product is olives eaten out of hand or drizzled from golden bottles of silky oil, harvesting and processing olives at home is a nutritional, gratifying reconnection with a deep agricultural and culinary history.