What Is Cooking Oil?

When I first learnt to cook, I knew in most dishes, I had to use oil. I didn’t think much about it, what it was made of, or why. I just splashed it in and went on my merry way. After studying nutrition and learning more about oil’s flavors and health benefits, I paid more attention to what I used to cook my food in. Today, we will talk about what exactly a cooking oil is and what it does to your food!

Cooking oils are usually derived from fruits like olive, avocado, and coconut, from vegetables such as corn, from legumes like peanuts and soybeans, and from nuts and seeds like walnuts, canola, and sunflower. Then there are the cooking fats, usually from animals, such as beef tallow and lard. 

These oil sources offer a wide range of flavors and nutritional benefits, making them crucial ingredients in countless recipes. It is needed in so many dishes, and selecting the right oil can greatly enhance the taste and texture of dishes while providing essential fatty acids and vitamins.

Cooking Oil Over Time

Throughout history, people have used various fats extracted from food to meet their cooking needs. Fats like tallow, lard, and butter were commonly used for culinary purposes. As civilizations developed, different regions began processing vegetable oils to cater to their specific requirements.

Early civilizations employed different methods to obtain these oils. They would use the sun, fire, or ovens to heat oily plant products, causing them to release their oils that could then be collected. As early as 2000 BCE, the Chinese and Japanese produced soy oil. In ancient Egypt, palm oil was used for cooking around the same time. Southern Europeans, on the other hand, had started making olive oil by 3000 BCE, capitalizing on the abundance of olive trees in the region.

Interesting cooking practices were observed in other parts of the world as well. For instance, in Mexico and North America, peanuts and sunflower seeds were roasted, beaten into a paste, and boiled in water. The oil that rose to the surface could then be skimmed off. In Africa, palm kernels and coconut meat were grated, beaten, and boiled to derive oil.

Over time, new vegetable oils have become available with the advancement of extraction technology, such as corn oil and soybean oil. Other oils, such as grapeseed, watermelon seed oil, and olive pomace oil, are now being explored as viable alternatives to make use of parts of the plant that were once considered waste.

While the earliest pressing methods could retrieve only about 10% of the available oil, modern techniques, including solvent extraction, can capture a much higher percentage, up to 99.5%!

What Cooking Oil Does To Your Food

Oil in cooking really does enhance your food. It allows for higher cooking temperatures than water, resulting in faster and more flavorful food. It also aids in heat distribution, minimizing the risk of burning and ensuring even cooking. If you choose an oil that adds flavor, it can increase the taste and complexity of your dish too. Oil also adds textures, such as a crisp exterior or golden brown color, enhancing the visual appeal and the ‘crunch’ of food.

Beyond cooking, oil can be used for flavor that does not involve heat, such as salad dressings and dips. In baking, fats are responsible for creating a flaky texture and promoting the formation of air pockets, contributing to cakes’ lightness. In dough making, adding fat improves the gluten network’s expansion, making the dough easier to mix and handle. Whether in dough or cake batter, fat is a moisture retainer, preventing premature drying.

Types of Cooking Oil

Plant-based oils and animal fats are derived from different sources, and extraction methods vary accordingly. Plant oils are typically pressed, while animal fats are usually rendered. 

Animal-sourced fats:

Plant-sourced oils:

Beef tallow, Butter, Chicken fat (schmaltz), Duck fat, Ghee (clarified butter), Lard (Pork fat), Shortening

Almond oil, Apricot kernel oil, Avocado oil, Canola oil, Cashew oil, Coconut oil, Virgin/Unrefined Coconut oil, Refined Corn oil, Cottonseed oil, Flaxseed oil, Grapeseed oil, Hazelnut oil, Hemp oil/hemp seed oil, Macadamia oil, Margarine (hard stick), Margarine (soft), Olive oil (Extra Virgin), Olive oil (Light/Pure/Regular), Olive oil (Virgin oil), Olive pomace oil, Palm kernel oil, Palm oil/Red palm oil, Peanut oil, Pecan oil, Pistachio oil, Pumpkin seed oil, Rice bran oil, Safflower oil, Sesame oil, Soybean oil, Sunflower oil, Vegetable oil, Vegetable shortening/Crisco, Walnut oil, Wheat germ oil

Extraction and Processing Methods Of Cooking Oil

Plant-sourced oils for food undergo mainly two processing methods: pressing and extraction. Pressing involves using physical force to extract the oil from the plant. Extraction involves dissolving the oil in a solvent to separate it from other plant material. The extraction process includes methods such as cold pressing, expeller pressing, and centrifugation.

Animal fats, in contrast, are typically obtained from animal tissue and then rendered or processed. Rendering is a process where animal fat is heated to separate the fatty acids and glycerol molecules. This also involves removing moisture and other elements to make the fat suitable for cooking. Processing involves combining animal fat with vegetable oils, emulsifiers, or stabilizers to create products like lard or shortening.

When it comes to oil refining, there are two main categories: unrefined oils and refined oils. Unrefined oils are minimally processed and retain their original flavor, aroma, and nutritional value. Examples of unrefined oils include olive oil, sesame oil, coconut oil, avocado oil, and almond oil. However, refined varieties are available for these oils if you prefer a milder taste.

Refined oils have undergone processing to remove impurities such as chemicals and odor. Refined oils generally have a longer shelf life, higher smoke point, and neutral taste or smell. Common examples of refined oils include canola oil, corn oil, vegetable oil, and cottonseed oil. The refining process means losing nutritional value and flavor in oils.

Health Implications of Different Cooking Oils

Cold pressing is widely regarded as the gold standard for processing cooking oils because it can preserve the oil’s nutritional value without using chemicals. Many experts agree that cold-pressed oils offer a healthier alternative to refined cooking oils. They are cholesterol-free, unprocessed, and do not contain harmful solvents or residues. They also retain natural antioxidants that provide benefits to the body.

Although cold pressing is unsuitable for all oil sources, as it may result in undesirable trace elements, it remains the safest and healthiest method for extracting oil. It may take longer and yield less, but the oil’s natural nutrients, texture, and aroma remain intact. Compared to expeller-pressed oils, cold-pressed oils offer a greater aroma, flavor, nutritional richness, and color.

Refined cooking oils have been scrutinised recently, particularly those high in polyunsaturated fats (specifically omega-6). While omega-6 is an essential fatty acid that we need, we tend to eat too much of it. Too much omega-6 and not enough omega-3 may lead to chronic inflammation, though more large-scale human studies are needed.

Storage and Shelf Life, The Best Practices for Cooking Oil

When oils are exposed to oxygen, light, or heat, they undergo oxidation, resulting in rancidity. Therefore, it is advisable to tightly seal and store cooking oils away from heat and sunlight, preferably in a dark pantry and separate from appliances. While most cooking oils can be stored at room temperature, certain oils can benefit from refrigeration. By keeping them at lower temperatures after opening, many oils actually have an extended shelf life.

Different oils will also have different storage requirements. For example, extra virgin olive oil is easily damaged by light. As such, leaving olive oil on the counter or a table, especially if the bottle gets direct sunlight, is not the way to keep it for more than a few days.

Coconut oil has excellent stability, with a shelf life of two years or more when stored at room temperature. Unlike most other cooking oils, it remains unaffected by heat or light, preserving its quality over time. Being solid below 76 degrees Fahrenheit, it may need to be scooped rather than poured in most indoor settings.

To preserve the quality of walnut oil and chia seed oil, be aware of their high susceptibility to oxidation. It is recommended to store these and other delicate oils in the refrigerator once opened. By keeping them cold, these oils can retain their viability for at least six months.

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