How to Preserve Food: the Olive Oil Technique

By way of introducing myself to the Self-Sufficiency Gate, I wrote a small post on how to preserve food by using olive oil.

How to Preserve Food: the Olive Oil Technique

Introduction

Preserving food is a cornerstone of self-sufficiency and has been practiced for centuries to make seasonal or excess food last longer. Before modern refrigeration, our ancestors learned to use various methods – from drying in the sun to storing in salt – to keep food edible through winter or droughts. By learning these time-tested techniques, beginners in self-sufficiency, food enthusiasts, and survivalists can reduce waste, enjoy off-season foods, and gain a valuable skill for an emergency. Below, we’ll explore the way to preserve food in olive oil, an ancient method experiencing a revival today.

Preserving Food in Olive Oil

Submerging foods in olive oil is an ancient Mediterranean preservation method. By fully covering ingredients with oil, you create a seal that keeps out air, moisture, and mold, thereby slowing down spoilage. This technique – often called oil packing or confiting – can preserve a variety of foods like vegetables, herbs, cheese, or even cooked meats for weeks or months, all while infusing them with rich flavors from the olive oil and seasonings. However, it’s crucial to do it properly: olive oil itself doesn’t kill bacteria, and in fact an oil-filled jar creates an oxygen-free environment where certain harmful bacteria can thrive if introduced. Don’t be alarmed – people have safely preserved foods in olive oil for generations, but you must follow guidelines to ensure safety.

Why Olive Oil Works (and When It Doesn’t)

Olive oil is particularly well-suited for preservation because of its stability and properties. It is mostly monounsaturated fat, meaning it oxidizes and turns rancid more slowly than many polyunsaturated oils, so properly stored olive oil can protect food for a longer time without spoiling. When you cover food completely in oil, it isolates the food from oxygen, which greatly delays oxidation and mold growth on the food. The oil basically embalms the ingredients, keeping out air and airborne microbes. A real extra virgin olive oil is often recommended for this purpose – not only for its superior flavor but also because a high-quality extra virgin oil tends to have natural antioxidants and low acidity, which can help keep the preserve fresh. In contrast, if you use a poor-quality or old/rancid oil, your preserved food may develop off-flavors or spoil within days. Any pure olive oil can create the air-blocking seal, but a fresh (max 12 months old since harvest), premium extra virgin oil (acidity < 0.3%) will keep foods safer and tastier for longer. Always ensure the oil itself is not contaminated with water or particles – cloudy, unfiltered oils with sediment might carry moisture or impurities that could cause spoilage.

Foods Ideal for Olive Oil Preservation

Many ingredients preserve well in olive oil, especially those that are low in moisture or cooked:

• Dried or Roasted Vegetables: Semi-dried tomatoes, roasted peppers, grilled zucchini or eggplant, and sautéed mushrooms work well. Cooking removes moisture, reducing spoilage. Cool before jarring, add herbs or salt, and cover fully with oil. Stored in the fridge, they can last up to 6 months.
• Herbs and Leafy Greens: Basil, rosemary, oregano, and chili peppers infuse well in oil. Make sure they’re fully dry. Pack in sterilized jars and submerge in oil. Leafy herbs may need replacing after a few weeks.
• Cheeses: Feta or goat cheese can be cubed and marinated with herbs and oil. Their salt and acidity help preservation. Store in the fridge and consume within 1–2 weeks. Always use clean kitchen tools to avoid contamination.
• Cooked Meats and Fish: Fully cooked meats (like confit duck or oil-poached chicken) and fish (like tuna or sardines) can be stored under oil. The oil seals and protects; cooking makes them safe. Always refrigerate and consume within a few weeks.

In general, use cooked, dried, or acidic foods for oil preservation. Avoid anything raw and moist.

Foods You Should Not Preserve in Oil

Some foods are unsafe to preserve directly in oil due to the risk of bacteria:

• Raw Garlic & Low-Acid Veggies: Garlic can carry botulism spores. Never store raw garlic or fresh mushrooms, peppers, or chilies in oil at room temperature. If using, acidify first or refrigerate and use within a week.
• High-Moisture Foods: Wet foods like raw tomatoes, cucumbers, or fresh meat promote bacteria and mold. Always dry, roast, or pickle before packing in oil. Never add water or broth to jars.
• Uncooked Meats: Raw meat in oil is dangerous. Only use fully cooked or cured meats.