The oil that seemed perfect until the sediments spoke

Uncle Sayed, the owner of the olive oil press, hurried into the lab, carrying a bottle of fresh olive oil that had been cold-pressed just a few days prior. He was confident in the quality of his product, having overseen the pressing process, and was eager to hear the results.

Uncle Sayed said, "Engineer, this is fresh, cold-pressed oil, from the finest olives. It's impossible that the results I received are correct."

Engineer Mahmoud calmly replied, "I appreciate your concern, and the oil certainly looks fresh. However, the analysis showed a slight increase in acidity, a significant rise in peroxide, and indications of sediment fermentation beginning."

Uncle Sayed asked in surprise, "Fermentation? The oil hasn't been in the tank for long, how can this happen?"

Engineer Mahmoud replied, "The problem isn't with the oil itself, but with the sediments that weren't removed after settling. These sediments start reacting quickly, especially in unfiltered oils."

Uncle Sayed paused for a moment, as if hearing this information for the first time, then said, "Alright, explain more to me... How do sediments affect the oil?"

Engineer Mahmoud smiled and began to explain in precise scientific detail.

The Impact of Not Removing Sediments from Olive Oil After Settling

What Are Sediments?Sediments are a natural mixture found in fresh oil, but their continued presence without removal causes real problems. These sediments consist of:

• Pulp residue.
• Tiny pieces of skin.
• Vegetable water droplets.
• Solid particles not separated during pressing.

Chemical Effects

• Increased Acidity: Sediments contain water and organic matter that decompose over time, leading to an increase in free acidity, a significant rise in the peroxide value, and a deterioration in quality. This consequently moves the oil to a lower classification (which is what the quality engineer observed in the analysis).
• Accelerated Oxidation: Sediments provide an environment that accelerates oxidation, leading to the appearance of rancid odors, loss of fruity flavor, and a decline in nutritional value.
• Fermentation: The presence of water within the sediment causes organic matter to ferment, producing gases, developing undesirable odors, and a 'muddy' or 'rancid' taste (a concern for mill owners as it quickly appears in unfiltered oils).

Sensory Effects

• Odor: Undesirable odors such as mold, mud, and fermentation may appear; these are sensory defects that disqualify the oil from the 'Extra Virgin' category.
• Taste: The oil becomes less fruity, develops an unpalatable and undesirable bitterness, and has a taste suggestive of 'sedimentation'.
• Color: The oil becomes darker, cloudy, and less transparent.

Health Impacts

Neglecting to remove sediment leads to:

• Loss of some antioxidants.
• Decline in the oil's health benefits.
• Increase in harmful compounds resulting from decomposition.

Economic Impacts

• Decrease in the oil's price and market value.
• Difficulty storing the oil for long periods.
• Financial losses for farmers and mills.
• Need for re-filtration or disposal of part of the production.

Best Practices to Avoid the Problem

To ensure oil quality and avoid these defects, it is recommended to follow these steps:

• Allow the oil to settle for a period ranging from 15 to 30 days.
• Periodically remove sediments from the bottom of the tanks.
• Use tanks made of stainless steel.
• Avoid exposing the oil to heat and light.
• Filter the oil as needed.

Conclusion

What transpired in the lab between Uncle Sayed, the oil owner, and Engineer Mahmoud, the quality engineer, is not an isolated incident but a common reality for many producers. Although sediments are a natural component of fresh oil, they can quickly lead to quality degradation if not removed promptly. Therefore, understanding their impact and implementing proper decantation and storage practices is crucial for producing high-quality olive oil that retains its flavor, nutritional value, and economic worth.

You can learn the difference between filtered and unfiltered olive oil from here