Vegetable oils and derivatives

Food, Plant source foods

Consumption area(s): Earth

Introduction

Vegetable oils are fats extracted from seeds or other parts of edible plants. Like animal fats, they consist mainly of triglycerides. Common examples include soybean oil, grapeseed oil, and cocoa butter, which are obtained from seeds, whereas olive oil, palm oil, and rice bran oil are derived from other parts of the plants.

Description of vegetable oils

Generally, the term “vegetable oil” refers to those fats that remain liquid at room temperature (although in some cases they may also be found in a solid state). In other instances, solid vegetable fats can be produced as derivatives from liquid vegetable oils.

Vegetable oils serve various culinary functions. They contribute to the structure of foods, giving baked goods a more crumbly texture, enhancing flavor, and increasing caloric content. Some oils, such as sesame or almond oil, are used for their distinctive aroma, while others act as a flavor base, intensifying the taste of ingredients. Due to their high smoke point, many vegetable oils are preferred for frying, including soybean oil, canola oil, peanut oil, and tropical oils like coconut and palm oil, which are widely appreciated in Asian cuisines.

Regarding storage, vegetable oils, especially those rich in polyunsaturated fatty acids, are prone to oxidation when exposed to oxygen, heat, and light, leading to the formation of harmful compounds such as peroxides and hydroperoxides. This process shortens their shelf life, making proper handling and storage essential to maintain their quality.

History of vegetable oil

The use of olive oil dates back to ancient times, with evidence of its production as early as 6000 BCE in the region of present-day Israel. In ancient Egypt, it was valued not only as a food ingredient but also for body care. In West Africa, palm oil had been widely used for centuries and became a valuable commodity in trade with Europeans, who began exporting it for various applications.

In 1901, German chemist Wilhelm Normann developed the hydrogenation process, which led to the creation of trans fats used in the production of margarine and other solid vegetable fats. In the United States, cottonseed oil was processed by Procter & Gamble, which launched the famous Crisco in 1911 — a solid vegetable fat at room temperature, ideal for cooking.

During the 20th century, soybean oil gained prominence due to its high content of polyunsaturated fats, becoming the most widely used oil in the U.S. during the 1950s and ’60s. Its versatility allowed it to be used in numerous food preparations. Today, global production is led by China, the United States, Argentina, and Brazil. Another important innovation was the development of canola oil, a variety of rapeseed low in erucic acid, bred in Canada during the 1970s. Thanks to its light texture and neutral flavor, canola oil became a valuable alternative to soybean and corn oils, establishing itself as one of the most widely used vegetable oils worldwide.

Vegetable oils production method

The extraction of vegetable oil involves separating the oil from seeds or other parts of the plant. This process can be carried out through mechanical methods, such as pressing, or by chemical extraction using solvents. The extracted oil is then subjected to purification stages and, if necessary, further treatments to modify its properties.

Mechanical extraction, also known as pressing, is commonly used to produce oils like olive or coconut oil. This method is favored in markets that prioritize quality and health, particularly in Europe and the United States. Popular techniques include the screw press, the expeller press, and the ghani, a traditional system employed in India. The yield varies depending on the technique used and the type of seed processed.

On the other hand, solvent extraction is faster and more efficient from an industrial perspective. Hexane, a petroleum derivative, is commonly used to achieve higher yields from seeds such as soybean and corn. After extraction, the solvent is removed through a hot evaporation process, leaving only the oil behind. A more recent alternative is the use of supercritical carbon dioxide, which leaves no chemical residues.

To improve the quality of the oil, deodorization is also applied, eliminating unwanted odors and flavors, although it may alter the nutritional composition.

For some applications, hydrogenation is performed to modify the structure of fatty acids and produce fats that are solid at room temperature, such as margarine. This transformation occurs by reacting the oil with hydrogen in the presence of a metal catalyst like nickel. Complete hydrogenation results in saturated fats, while partial hydrogenation generates trans fats, which are linked to health issues.

Classification of vegetable oils

Vegetable oils are primarily classified based on the plant source from which they are extracted. Accordingly, we find:

• Coconut oil
• Cottonseed oil
• Corn oil
• Olive oil
• Palm oil
• Peanut oil
• Rapeseed oil
• Sesame oil
• Soybean oil
• Sunflower oil