Well done from the beginning

Vegetable crude oil and fats come with a very wide specification range, so both the chemical treatment as well as the equipment involved in processing them must be assertive and exact. Each batch of crude vegetable oil and/or animal fat has to be refined its own way. We cannot treat each one equally. No matter what the raw material quality is, it is key during the refining process to focus on storage conditions and chemical pre-treatment.

So, why is a good chemical pre-treatment important? It is well known that many impurities are found in the crude/degummed oil and fats, but the most difficult to remove are the Non-hydratable phosphatides (NHP). They are complex molecules that are joined to a non-metal or metal component, like Ca, Mg, Fe and Cu and others, and they cause poor stability of cooking oil and fats. Even if a processor has the most efficient processing set up downstream, if you did not do a very good job during the chemical pre-treatment process, then irreversibly, you will lose quality in the end product and make the downstream process inefficient. Therefore, it is very important to do the pre-treatment well from the beginning.

First of all, we must have accurate and timely analysis. It is impossible to treat or fight what we do not see or know.

Then we must choose the right treatment. Some people think that over-treatment is a good solution, but it is not and will have high costs and cause other problems. An NHP is not hydratable, so it must be reverted and converted to a polar molecule by treating it with acid. Normally the industry uses phosphoric and/or citric acid, so we must use the right amount of acid along with the perfect mixing, retention time, and temperature, with the last two being essential and dependent on each other.

Also, we need to be aware that the conversion from NHP to HP is not stable and could revert from HP to NHP very easily.

For example, at a specific temperature if the retention time is exceeded, then you will have a revert problem, or if the retention time is less than required, the conversion will be incomplete, so you are not going to be able to remove the all impurities efficiently. It does not matter if you are doing chemical or physical refining, or even if you are doing enzymatic refining, pre-treatment is key.

Some people think that neutralization and/or bleaching will complete the job, but they will not and they will produce big losses in soap stock, wash water, and clay. Of course, if you are doing physical refining, it must only be on clay.

In the case of Palm Oil, pre-treatment is key to avoiding or minimizing the appearance of 3MCPD’S and Glycidyl Ester. The right chemical addition and reaction control will avoid problems in the finished product.

We must always remember that we are processing cooking oil. Once we have all the phosphatides hydratable or polar, we can trust, if the set up of downstream in the remaining process is set up efficiently, to take them out of the oil. Therefore, not just they will bond to the water included in the caustic solution in the neutralization process, but also, the bleach clay will catch them, so it will be the right condition for the crude to go proceed further with the downstream process.

Consequence of the wrong pre-treatment

It is well known that a finished refined oil with more than 1ppm content of impurities will have the following problems:

• High process costs due to reprocessing, high shrinkage, and bad chemical control.

• Low stability or high oxidation.

• High 3MCPD’S and glycidyl ester content.

• Bad flavor/odor and costumer complaints.

Note: Even color fixation can occur in the case of very bad pre-treatment.

How to avoid those problems

As mentioned above, the design of the pretreatment process needs to focus on:

• Accurate and timely analysis.

• Perfect and intimate mixing.

• Correct retention time and temperature.

Therefore, it is very important to fulfill the requirements. Then, through the optimization and control of the chemical reaction and subsequent re-engineering of the pre-treatment process, refiners could efficiently remove impurities from a wider range of quality crude oils and fats. Together with an efficient set up on the further downstream process, processors will get an excellent stabled quality finished product, increasing efficiencies, refining capacity and achieving long-term sustainable and substantial savings while attaining high food safety standards.

Double R&D

Double R&D helps companies increase their profitability by increasing efficiency and yields in processing edible oils and fats through chemical reaction engineering. Our proven approach generates long-term process improvements that support our clients’ sustainable financial growth and success.