In this very article, I am going to showcase cold press method of extraction. I would let
you all know what it is, how the process works, why it is so preferred along with its disadvantages.

It is widely preferred technique and mostly used for citrus family and other carrier oils. Essential oil has been in use since ancient time. The way these oils been used to enhance health, beauty and wellness was commendable. The increasing emergence of oils made people wonder about their extraction process.

Though there are various other methods like steam distillation, super-critical CO₂ extraction. In this section we will limit our discussion till cold press method of extraction. Hope you all are curious to read ahead, come along.

Cold press method

It is a type of mechanical extraction and extracts oil from oil seeds, peels or fruit of plant. It is also known as mechanical separation or expression or expeller pressing. The technique is specifically used for citrus family oils like orange, lemon as the essential oils are stored in the skin or epicarp of citrus fruits. 

The process is termed as ‘cold’ press because there is no heat involved. Naturally oil seeds can be just crushed to extract oil. Sesame seeds, coconut, groundnut are some raw materials from which oil can be retrieved by just pressing.

History of cold-press method

• Origin of cold pressed oil dates back to the Indus Valley Civilization. Burnt sesame seeds and oil pressing machine was found in the remains of Harappa which were dated 5000 years old.

• The cold press method of extraction received its name from the German words kalt geschlagen. The word mentioned means ‘cold pummeling’. It is believed that it refers to the intensive pressure that seeds and fruits bear.

• The process was pioneered in Italy in the 19^th century and it then expanded to Brazil, California and Florida.

• Chekku, Ghani and Kholu are somespoken words which are commonly used in India to depict cold press oils. Actually these words refer to the oil pressing machine which is used to extract oil.

Cold press process of Extraction:

Cold press method is a mechanical separation process where crushing of nuts or seeds takes place and forcing out of oil through pressure is done. In ancient days, a long cylindrical contraption known as ‘Ghani’ was used for extraction of oil from oilseeds. It was mentioned in some book that Ghani was a pestle and mortar device that was made of stone or wood. It involves extraction of oil under pressure from oil bearing seeds. This is regarded as the uncomplicated method of oil extraction. It also did not involve too much generation of heat. Nowadays these Ghanis are replaced by modern extraction machines. Mechanical press methods are also referred as solid-liquid phase separation used for oil extraction with oil content below 20%. Pressure is an important parameter that is applied for extraction. Temperature is applied optionally, a process without temperature refers as cold press method and that with temperature application called as hot press method.

In very simple terms, raw materials are pressed under pressure which results in oil yield along with a residue that is commonly referred as oil cake. There is no external heat source provided for extraction of oil. The temperature of the oil during process is less than 50°C usually done at 27°C. The pressing or grinding process results in friction which is responsible for this temperature which is slight above room temperature. Temperature controls of oil helps to retain essential nutrients and flavor that usually get lose at high temperatures. In earlier days, cold pressed oils were extracted by hand and made use of specialized sponges that helped to absorb plants oil and liquid. These sponges were then pressed in a vice-like device over a container. This helped to separate oil from rest of the plant liquid. But the process was labor intensive and also time-taking. In present scenario, the process is less labor intensive. Even modern cold press machines utilize centrifugal force for separation of oil from plant liquid.

Cold-press machine and working

As we know that it is a mechanical process of oil separation.

Traditionally, raw material was first grounded into a paste and this was pressed with a heavy stone mill turned by bullocks until it extracts the oil. But with the advent of technology, cold press machines are used. 

Today, there are various cold press extraction methods are available which depends on the part of the plant oil that we have to extract. Bladder press extraction, Hydraulic presses, low resistance expeller pressing, modified atmosphere crushing and modified atmosphere packaging are some of latest extraction methods. Presses vary in their size; it is available in small size for home use and also has commercial or industrial use presses for oil extraction. Cold press machine has one inlet for feeding raw material or seed and two outlets or exits. One exit is for extracted oil and other is for non-oiled cake. 

Raw material for the process (seeds, nuts, or fruits) are collected and thoroughly cleaned to get rid of impurities. Take for instance our material is seeds. Seeds are then placed inside a cylinder that contains rotating screw.

When the machine is activated, screw helps in grinding and crushing of seeds, and exposes the oil containing sacs until the oil is extracted. Small holes in the bottom of the cylinder allow oil to escape in the collection container. It is then strained to avoid any solid pulp pieces and to maintain quality.

As the screw breaks the seeds, friction force causes generation of heat. But this heat is not enough to damage the oil. This is referred as first pressed oil which is generally sold unrefined and without any chemical additives or preservatives and this is actual cold pressed oil. The oil extracted from the first pressing is of finest quality and purity.

Commonly cold pressed oils

Now when we are done with the process of cold press, you must be thinking which oils are generally obtained using this technique, am I right?

Weare now well familiar with essential as well as carrier oils. So let me tell you not all essential oils are obtained using this technique. It is only citrus family oil like bergamot, orange, lemon that utilizes cold-press method. Carrier oils are mostly obtained by technique of cold-pressed method. Some carrier oils are listed below:

• Olive oil,
• Almond oil (Sweet and bitter almond)
• Hemp seed oil
• Coconut oil
• Mustard oil
• Flaxseed oil, etc.

The list is very long and I am not going to mention all oils here. These are some common carrier oils and I am sure you are heard of them and using them in your daily life. But it should be noted that not all carrier oils can be retrieved using this method. Some raw materials like Brazil nuts and tomato seeds both have high moisture content. Those plants which have high moisture content require more heat for extraction of oil unlike cold press oil which operates at no external heat.

Benefits of cold pressed oils

There are multitude benefits of cold pressed technique and one should know about such 
     added benefits. This helps to make good choice when you shop for your favorite oil. I have
     listed below benefits of cold pressed oils:         

• Cold pressed oil involves no external heat and so they are loaded with essential antioxidants and vitamins.

• They are rich in Vitamin E.

• Cold pressed oil has biological activities like antibacterial and anti-inflammatory that prevents exposure to infections.

• Heat generally degrades Vitamin C. Thus cold pressed oil acts as good source of Vitamin C which penetrates into the skin and provides healthy skin.

• Cold pressed oils are pure oils and are best oils in terms of purity. This is because the oil has been forced out by pressure and no application of heat or harmful chemicals has been added.

• Cold pressed oils are generally employed for carrier oils. Some of these oils are rich source of oleic acid which boosts immunity.

• Cold pressed oil also contains cancer fighting properties.

• Carrier oils are generally odorless and some edible oils like olive oil retain good flavor because of cold press method. So these edible cold pressed oils are used for cooking and baking.

• Cold pressed oils have various benefits for skin and hair.

Cost of cold press method

So after discussing this much, we are going to see the cost involved in this process. Let me warn you before, cold press oils are quite expensive.

Though it is traditional method of oil extraction, but the cost involved is little high. Cold pressed oil extraction efficiency is usually about 60-70% only which contributes to the cost of the oil.

Cold pressed oil Vs Refined oil

You all must have come across terms like refined oil and cold pressed oil which confuse consumers. So a layman generally boggles as the two oils are similar in appearance.

But to be frank, if you need oil that actually benefits you, little knowledge of these terms is foremost.Cold pressed oils are way healthier than refined oils. This cold pressed oil retains vitamins and nutrition which actually make them talk of the town. There are no chemicals added during the complete process. They are also more aromatic and hence add more taste to dishes.

Refined oils are those oils which undergo filtration process through various chemicals and heat which makes the final product very light and shiny in texture. Refined oils do not retain much nutrition in food. It gets lose due to application of heat and chemicals. These oils are rich in fat and devoid of nutrition. We generally prefer refined oils for cooking purpose as it is believed that they maintain heart health. But it is actually cold pressed oil that should be used to exploit their benefits.

Without taking more of your time, I would quickly like to jot some of the disadvantages of this technique and with that I will wrap my article.

Disadvantages

The most notable disadvantage of this technique is cost of the process and oil yield. Both these are linked with each other. Cost of the process is high because of the low yield.

Storage

Cold pressed oils have a very good shelf-life of approximately 6 months. But to maintain them in that situation proper storage is an important aspect. Cold-pressed oils should be kept  in a dry place and that too away from sunlight.

  Thank you.