Oilseed press facts for kids

An oilseed press is a special machine that helps us get oil from different kinds of seeds. Think of it like a giant juicer for seeds! This machine squeezes out the valuable oil, leaving behind something called "oilseed meal." Both the oil and the meal are super useful. The oil is great for cooking and other things, and the meal is packed with nutrients, especially protein, which is good for animals to eat. Oilseed presses are a key part of a bigger system that cleans, prepares, and then processes the seeds.

Types of Oilseed Presses

Getting oil from seeds might sound simple: just squeeze them! But there are many different ways to do it. Over time, people have invented various types of oilseed presses. Each type has its own strengths and weaknesses. We can group these presses into three main categories: traditional, manual, and powered.

Traditional Presses

Traditional presses have been used for a long time, especially in places like India.

• Ghani: This is like a huge mortar and pestle. An animal, like a bullock, or a motor turns a big wooden pestle inside a bowl (the mortar). This grinds and presses the seeds, and the oil slowly drips out.
  • Advantages: They don't need much power, can be made locally, and produce good quality oil.
  • Disadvantages: They are slow, and animals get tired. It's a "batch" process, meaning you press a small amount, then clean it out, and start again.
• Water Extraction: With this method, crushed seeds are boiled in water. The oil floats to the top, and you can skim it off. Then, the oil is heated again to remove any water.
  • Advantages: Simple tools are needed, and the final heating helps the oil last longer.
  • Disadvantages: You don't get much oil, it takes a lot of work, and boiling uses a lot of fuel.
• Other Traditional Methods: People have also used simple tools like wedges, levers, heavy stones, or twisted ropes to press oil.
  • Advantages: Very simple and easy to access equipment.
  • Disadvantages: They get very little oil and require a lot of physical effort.

Manual Presses

Manual presses are operated by hand and are a step up from the simplest traditional methods.

• Cage Press: Imagine a strong cylinder with holes. You put seeds inside, and then a plate or piston is pushed down with a screw or a lever. This squeezes the oil out through the holes.
  • Advantages: You can apply strong pressure to get out almost all the oil. They are also easy to use.
  • Disadvantages: Like traditional presses, they work in "batches." You have to clean them out after each batch of seeds.
• Ram Press: This press uses a piston that is pushed through a horizontal cylinder by a lever. As the piston moves back, more seeds automatically fall into place. A small opening at the end lets the pressed material out and helps control the pressure.
  • Advantages: They can work continuously, meaning you don't have to stop and clean them after every batch. Smaller models are easy for anyone to use. They are also very efficient and can be made and fixed locally. You don't even need to remove the outer shells of soft seeds.
  • Disadvantages: They might get damaged or not work well with very hard seeds.

Powered Presses

Powered presses use electricity or fuel to run, making them much faster and more efficient.

• Expeller: This is the most common type of powered press. Inside, a rotating screw (called a worm) pushes the seeds through a cylinder. As the seeds move, the pressure slowly increases, squeezing out the oil. A special adjustable part at the end lets you control the pressure.
  • Advantages: They work continuously and can process a lot of seeds, from a few pounds to many tons per hour. The friction inside the machine also creates heat, which helps get more oil out.
  • Disadvantages: They need electricity or fossil fuels to run. The oil they produce might not be as high quality as oil from "cold-press" systems. Parts like the rings and the screw can wear out quickly, so you need to have spare parts and skilled people to fix them.

What Comes Out: Oil and Meal

No matter which type of press is used, you always get two main products: oil and oilseed meal (sometimes called "cake"). Both are very valuable!

Oilseed Meal: A Protein Powerhouse

After the oil is squeezed out, the leftover oilseed meal is super rich in protein. Most oilseed meals have about 40% protein. This makes them excellent food for farm animals like cattle.

• Soybean Meal: This is a superstar! It has a great mix of important nutrients, is easy to digest, and has high protein levels (44-50%). Because of this, soybean meal is used more than any other protein source for feeding animals around the world.
• Other Meals: Meals from plants like canola are also good for animals, but soybean meal is the most popular.

Vegetable Oil: Energy and Healthy Fats

The vegetable oil that comes out of the press is full of energy. It's a big part of what people eat every day.

• Healthy Fats: Vegetable oils mostly contain unsaturated fats. These include important fats like omega-3 and omega-6, which our bodies need but can't make themselves. In contrast, animal fats often have more saturated fats, which can be linked to heart problems if you eat too much.
• Different Oils, Different Amounts: The amount of oil in different seeds varies. For example, canola seeds have about 40-45% oil, while soybeans have about 20%. The amount of oil you get also depends on how well the press works. If less oil is extracted, the leftover meal will have more oil and be even more nutritious for animals.

How Oil is Extracted: The Whole Process

Getting oil from seeds isn't just about pressing. There are steps before and after the pressing itself.

Preparing the Seeds

• Cleaning and Drying: First, the seeds must be clean and dry. Removing things like rocks, dirt, and dust makes the press work better and prevents damage. Drying the seeds (to about 10% moisture) stops the machine from getting clogged and prevents mold from growing during storage.
• Removing Outer Shells: For seeds with hard shells, like sunflowers or peanuts, the shells need to be removed. This step, called "dehusking" or "decortication," helps the press work better and reduces the amount of material you need to process.
• Milling and Heating: Some seeds, like peanuts, need to be ground a bit before pressing. Also, heating the seeds before pressing can help get more oil out. For example, roasting soybeans helps get rid of things that are bad for animals. Even just warming sunflower seeds in the sun for half an hour can increase the oil yield by 25%!

After Pressing: Processing the Oil

Once the oil is pressed, it's not quite ready.

• Clarification: This is the first step. The oil is left to sit, allowing small bits of dirt or impurities to settle to the bottom. You can also heat the oil or filter it through a fine cloth for better cleaning. Clarification helps the oil last much longer, from days to months.
• Further Processing: There are other steps like "degumming," "bleaching," "neutralization," and "deodorizing." These make the oil even purer and remove strong flavors. However, these steps are often complex and not always done in smaller operations, especially in places where people like the natural flavors of unrefined oils.
• Storage: Finally, the oil needs to be stored properly. It should be kept in clean containers that are completely full, airtight, and opaque (so light can't get in). Store the oil in a cool, dark place.