How Olive Oil is Made: From Harvest to Press

Curious about how olive oil is made?

Olive oil is produced by harvesting ripe olives, crushing them to form a paste, and then pressing the paste to extract the oil. This process retains the olives’ natural flavors and health benefits, producing popular cooking oil used in kitchens worldwide.

In this article, I discuss:

• Harvesting olive oil and why timing is key
• Harvesting techniques used
• Milling and pressing processes

Key Takeaways

• The timing of olive harvests is crucial for the flavor of the oil. Early-harvest oils, picked when the olives are still green, boast intense flavors and vibrant colors, while mid-to-late harvest oils offer a milder taste and different hues.
• Some olives are hand-picked by skilled workers to ensure minimal damage, while others are shaken off the trees using vibrating rakes or trunk shakers for efficiency.
• Olive oil doesn’t just magically appear! After harvesting, olives are crushed and pressed to extract the oil, with early-harvest oils prized for their rich flavors and high polyphenol content.

Harvesting Olives: Timing is Key

Harvesting is a pivotal stage that significantly influences the final product’s quality. Harvest timing plays a crucial role in impacting the quantity and sensory attributes of the oil.

Early Harvest

The harvest season starts as early as September when olives are underripe and still green. Although these olives yield relatively little oil, their flavor is remarkably intense.

Oils extracted from early-harvested olives boast a longer shelf life and exhibit rich sensory properties, including flavor and aroma.

Notably, these oils often possess a low acidity percentage and feature Tuscan oils’ distinctive deep green hue characteristics.

Here are some characteristics of early-harvest olive oils:

1. Rich Flavor: Early-harvest olive oils have a strong and intense taste. They often taste herbaceous with a peppery kick, adding depth to dishes.
2. Bright Green Color: Because they’re made from olives that aren’t fully ripe, these oils have a vibrant green color. This color shows the oil is fresh and has many healthy stuff.
3. Healthy Antioxidants: Early-harvest olive oils are packed with antioxidants called polyphenols. These are good for you and help fight inflammation and other bad stuff in your body.
4. Lasts Longer: Because they’re made from young olives and have low acidity, early-harvest oils can stay fresh for a long time if you store them right.
5. Special Smell: These oils smell unique, like fresh grass or green apples. It’s part of what makes them so attractive to cook with.
6. Good for Cooking: Even though they have a strong flavor, early-harvest oils can still be used in many recipes. They can make salads tastier or add a nice finish to cooked dishes.

Mid to Late Harvest: Balancing Flavor and Maturity

Harvests typically occur between early November and late December. Olives harvested during this period may vary in ripeness, with some picked in the red-ripe stage. Blending these riper olives with earlier harvested ones aims to achieve a more balanced final product.

However, oils from olives harvested in the black-ripe stage generally exhibit inferior quality, characterized by higher acidity levels and diminished flavor.

Here is an expanded list of the features of these olive oils:

1. Milder Flavor: Mid to late-harvest olive oils have a smoother and less intense taste than early-harvest oils. They’re not as strong, with more of a fruity flavor and less bitterness.
2. Changing Colors: These oils may have different colors, ranging from shades of purple to black. This shows that the olives are more ripe when harvested, affecting the oil’s taste and color.
3. Less Antioxidants: Since they’re harvested later, mid-to-late harvest oils may have fewer antioxidants than early-harvest oils. This doesn’t mean they’re unhealthy; they just might not have as many good-for-you compounds.
4. Shorter Shelf Life: Because they have higher acidity levels, mid-to-late harvest oils may not last as long as early-harvest oils. It’s important to use them up relatively quickly to enjoy their fresh taste.
5. Subtle Aroma: These oils have a more subtle smell than early-harvest oils. They might still have some fruity notes but won’t be as strong or grassy.
6. Versatile in Cooking: Mid-to-late harvest oils are great for cooking dishes where you don’t want the olive oil flavor to overpower other ingredients. They’re good for sautéing, roasting, or using in recipes where you want a lighter touch of olive oil.

Harvesting Techniques

The method of harvesting significantly impacts the quality of olive oil. Some techniques used in harvesting olives include;

Hand-picking: The Most Precise Method

Hand-picking is highly respected for gathering olives because it keeps the fruit in good shape and maintains its taste.

Trained workers carefully choose the ripest olives, taking care not to bruise or harm them while picking. This method takes time and precision, but it results in top-quality olives known for their rich flavors and low acidity.

Mechanical Harvesting: Balancing Efficiency and Quality

Mechanical harvesting has changed how olive oil is made by making it faster and easier to meet the needs of today’s markets. Machines like vibrating rakes or trunk shakers shake the trees to get the olives off quickly, which is excellent for big farms.

However, sometimes, the machines damage the olives, causing bruises. To fix this, technology is getting better at making machines that are gentler on the fruit so we can still get good-quality oil efficiently.

Combination Approaches: Maximizing Yield and Quality

Some olive oil producers combine hand-picking and machines to get the best of both worlds. By combining these methods, they can maximize the benefits of each while minimizing the downsides.

For instance, they might use hand-picking for particular types of olives that need extra care, like the ones sold in fancy markets. But for big farms or olives that aren’t as delicate, they might use machines instead.

This way, they can ensure they get lots of good-quality oil while meeting the needs of different customers in the olive oil business.

Milling and Pressing: Preserving Freshness and Flavor

Once harvested, olives undergo milling and pressing processes crucial for extracting high-quality oil:

• Timely Crushing: Olives must be crushed within the first 24 to 36 hours of picking to prevent a rise in acidity levels, which could compromise the oil’s quality.
• Milling Process: The olives, typically crushed whole without prior stoning, are processed using granite millstones. The resulting olive paste is then layered onto mats called “fiscoli” and subjected to pressure in a press.
• Pressing: Under pressure, the olive paste releases a liquid of water and oil. This mixture is then centrifugated, where rapid spinning separates the oil from water and impurities.
• Centrifugation: The centrifugal separator removes all remaining water and impurities, leaving pure olive oil with superior sensory characteristics behind. Oils processed using centrifuges and mechanical or hydraulic presses meet the criteria to be classified as virgin olive oil.

Summary

Olive oil production starts with carefully timing the harvest. Olives are picked by hand or with machines to keep them in good shape.

After harvesting, olives are crushed to make a paste and then pressed to extract the oil. Early-harvest oils have strong flavors and green colors while mid-to-late-harvest oils are milder and can be different colors.

Some producers use both hand-picking and machines to get the best results. With new technology, making olive oil is getting easier while keeping the delicious flavors people love.

Frequently Asked Questions